diff mbox

[2/2] pwm: add Mediatek display PWM driver support

Message ID 1431336382-13167-3-git-send-email-yh.huang@mediatek.com
State New
Headers show

Commit Message

YH Huang May 11, 2015, 9:26 a.m. UTC
Add display PWM driver support to modify backlight for MT8173/MT6595.

Signed-off-by: YH Huang <yh.huang@mediatek.com>
---
 drivers/pwm/Kconfig             |   9 ++
 drivers/pwm/Makefile            |   1 +
 drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 235 insertions(+)
 create mode 100644 drivers/pwm/pwm-disp-mediatek.c

Comments

Matthias Brugger May 12, 2015, 12:37 p.m. UTC | #1
Hi YH,

2015-05-11 11:26 GMT+02:00 YH Huang <yh.huang@mediatek.com>:
> Add display PWM driver support to modify backlight for MT8173/MT6595.
>
> Signed-off-by: YH Huang <yh.huang@mediatek.com>
> ---
>  drivers/pwm/Kconfig             |   9 ++
>  drivers/pwm/Makefile            |   1 +
>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 235 insertions(+)
>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index b1541f4..9edbb5a 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -111,6 +111,15 @@ config PWM_CLPS711X
>           To compile this driver as a module, choose M here: the module
>           will be called pwm-clps711x.
>
> +config PWM_DISP_MEDIATEK
> +       tristate "MEDIATEK display PWM driver"
> +       depends on OF
> +       help
> +         Generic PWM framework driver for mediatek disp-pwm device.
> +
> +         To compile this driver as a module, choose M here: the module
> +         will be called pwm-disp-mediatek.
> +
>  config PWM_EP93XX
>         tristate "Cirrus Logic EP93xx PWM support"
>         depends on ARCH_EP93XX
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index ec50eb5..c5ff72a 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
>  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
>  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
>  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
>  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
>  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
>  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> new file mode 100644
> index 0000000..38293af
> --- /dev/null
> +++ b/drivers/pwm/pwm-disp-mediatek.c
> @@ -0,0 +1,225 @@
> +/*
> + * Mediatek display pulse-width-modulation controller driver.
> + * Copyright (c) 2015 MediaTek Inc.
> + * Author: YH Huang <yh.huang@mediatek.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define DISP_PWM_EN_OFF                        (0x0)
> +#define PWM_ENABLE_SHIFT               (0x0)
> +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)

Get rid of the _SHIFT which are actually zero, it will make the code
more readable.

> +
> +#define DISP_PWM_COMMIT_OFF            (0x08)
> +#define PWM_COMMIT_SHIFT               (0x0)
> +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> +
> +#define DISP_PWM_CON_0_OFF             (0x10)
> +#define PWM_CLKDIV_SHIFT               (0x10)
> +#define PWM_CLKDIV_MASK                        (0x3ff << PWM_CLKDIV_SHIFT)
> +#define PWM_CLKDIV_MAX                 (0x000003ff)
> +
> +#define DISP_PWM_CON_1_OFF             (0x14)
> +#define PWM_PERIOD_SHIFT               (0x0)
> +#define PWM_PERIOD_MASK                        (0xfff << PWM_PERIOD_SHIFT)
> +#define PWM_PERIOD_MAX                 (0x00000fff)
> +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> +#define PWM_PERIOD_BIT_SHIFT           12
> +
> +#define PWM_HIGH_WIDTH_SHIFT           (0x10)
> +#define PWM_HIGH_WIDTH_MASK            (0x1fff << PWM_HIGH_WIDTH_SHIFT)
> +
> +#define NUM_PWM 1
> +
> +struct mtk_disp_pwm_chip {
> +       struct pwm_chip chip;
> +       struct device   *dev;
> +       struct clk      *clk_main;
> +       struct clk      *clk_mm;
> +       void __iomem    *mmio_base;
> +};
> +
> +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> +{
> +       u32 val;
> +
> +       val = readl(address);
> +       val &= ~mask;
> +       val |= value;
> +       writel(val, address);
> +}
> +
> +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> +                              int duty_ns, int period_ns)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +       u64 div, rate;
> +       u32 clk_div, period, high_width, rem;
> +
> +       /*
> +        * Find period, high_width and clk_div to suit duty_ns and period_ns.
> +        * Calculate proper div value to keep period value in the bound.
> +        *
> +        * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> +        * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> +        *
> +        * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> +        * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> +        */
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       rate = clk_get_rate(mpc->clk_main);
> +       clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> +                               PWM_PERIOD_BIT_SHIFT;

You never use the remainder, so better use div_u64 to make the code cleaner.

> +       if (clk_div > PWM_CLKDIV_MAX)
> +               return -EINVAL;
> +
> +       div = clk_div + 1;
> +       period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> +       if (period > 0)
> +               period--;
> +       high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> +       if (high_width > 0)
> +               high_width--;
> +
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> +                            clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> +                            (period << PWM_PERIOD_SHIFT) |
> +                       (high_width << PWM_HIGH_WIDTH_SHIFT),
> +                       PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> +
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> +                            1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> +                            0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> +
> +       return 0;
> +}
> +
> +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> +                            1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> +
> +       return 0;
> +}
> +
> +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> +                            0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> +}
> +
> +static const struct pwm_ops mtk_disp_pwm_ops = {
> +       .config = mtk_disp_pwm_config,
> +       .enable = mtk_disp_pwm_enable,
> +       .disable = mtk_disp_pwm_disable,
> +       .owner = THIS_MODULE,
> +};
> +
> +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> +{
> +       struct mtk_disp_pwm_chip *pwm;
> +       struct resource *r;
> +       int ret;
> +
> +       pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> +       if (!pwm)
> +               return -ENOMEM;
> +
> +       pwm->dev = &pdev->dev;
> +
> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> +       if (IS_ERR(pwm->mmio_base))
> +               return PTR_ERR(pwm->mmio_base);
> +
> +       pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> +       if (IS_ERR(pwm->clk_main))
> +               return PTR_ERR(pwm->clk_main);

I prefer to have a newline after the if-then-ese block, which makes it
(at least for me) easier to read the code.

Thanks,
Matthias
Matthias Brugger May 12, 2015, 12:44 p.m. UTC | #2
2015-05-12 14:37 GMT+02:00 Matthias Brugger <matthias.bgg@gmail.com>:
> Hi YH,
>
> 2015-05-11 11:26 GMT+02:00 YH Huang <yh.huang@mediatek.com>:
>> Add display PWM driver support to modify backlight for MT8173/MT6595.
>>
>> Signed-off-by: YH Huang <yh.huang@mediatek.com>
>> ---
>>  drivers/pwm/Kconfig             |   9 ++
>>  drivers/pwm/Makefile            |   1 +
>>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 235 insertions(+)
>>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
>>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index b1541f4..9edbb5a 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -111,6 +111,15 @@ config PWM_CLPS711X
>>           To compile this driver as a module, choose M here: the module
>>           will be called pwm-clps711x.
>>
>> +config PWM_DISP_MEDIATEK
>> +       tristate "MEDIATEK display PWM driver"
>> +       depends on OF
>> +       help
>> +         Generic PWM framework driver for mediatek disp-pwm device.
>> +
>> +         To compile this driver as a module, choose M here: the module
>> +         will be called pwm-disp-mediatek.
>> +
>>  config PWM_EP93XX
>>         tristate "Cirrus Logic EP93xx PWM support"
>>         depends on ARCH_EP93XX
>> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
>> index ec50eb5..c5ff72a 100644
>> --- a/drivers/pwm/Makefile
>> +++ b/drivers/pwm/Makefile
>> @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
>>  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
>>  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
>>  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
>> +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
>>  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
>>  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
>>  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
>> diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
>> new file mode 100644
>> index 0000000..38293af
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-disp-mediatek.c
>> @@ -0,0 +1,225 @@
>> +/*
>> + * Mediatek display pulse-width-modulation controller driver.
>> + * Copyright (c) 2015 MediaTek Inc.
>> + * Author: YH Huang <yh.huang@mediatek.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/pwm.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +
>> +#define DISP_PWM_EN_OFF                        (0x0)
>> +#define PWM_ENABLE_SHIFT               (0x0)
>> +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
>
> Get rid of the _SHIFT which are actually zero, it will make the code
> more readable.
>
>> +
>> +#define DISP_PWM_COMMIT_OFF            (0x08)
>> +#define PWM_COMMIT_SHIFT               (0x0)
>> +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
>> +
>> +#define DISP_PWM_CON_0_OFF             (0x10)
>> +#define PWM_CLKDIV_SHIFT               (0x10)

I prefer to have the shift values in decimal instead of hex, as it
makes it easier to see which bits in the registers are the relevant
ones.
Sorry forgot that one.

Cheers,
Matthias
Sascha Hauer May 12, 2015, 1 p.m. UTC | #3
On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> +
> +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pwm;

The struct mtk_disp_pwm_chip * is named 'mpc' in the other functions.
For consistency reasons you should do that here aswell.

> +	struct resource *r;
> +	int ret;
> +
> +	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> +	if (!pwm)
> +		return -ENOMEM;
> +
> +	pwm->dev = &pdev->dev;
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(pwm->mmio_base))
> +		return PTR_ERR(pwm->mmio_base);
> +
> +	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> +	if (IS_ERR(pwm->clk_main))
> +		return PTR_ERR(pwm->clk_main);
> +	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> +	if (IS_ERR(pwm->clk_mm))
> +		return PTR_ERR(pwm->clk_mm);
> +
> +	ret = clk_prepare_enable(pwm->clk_main);
> +	if (ret < 0)
> +		return ret;
> +	ret = clk_prepare_enable(pwm->clk_mm);
> +	if (ret < 0) {
> +		clk_disable_unprepare(pwm->clk_main);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, pwm);
> +
> +	pwm->chip.dev = &pdev->dev;
> +	pwm->chip.ops = &mtk_disp_pwm_ops;
> +	pwm->chip.base = -1;
> +	pwm->chip.npwm = NUM_PWM;
> +
> +	ret = pwmchip_add(&pwm->chip);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> +		return ret;

This error path leaves the clocks enabled.

> +	}
> +
> +	return 0;
> +}
> +
> +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> +
> +	if (WARN_ON(!pc))
> +		return -ENODEV;
> +
> +	clk_disable_unprepare(pc->clk_main);
> +	clk_disable_unprepare(pc->clk_mm);
> +
> +	return pwmchip_remove(&pc->chip);

You should first remove the pwmchip and disable the clocks afterwards.
Also note that this function can fail.

Sascha
Thierry Reding May 12, 2015, 1:32 p.m. UTC | #4
On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> Add display PWM driver support to modify backlight for MT8173/MT6595.
> 
> Signed-off-by: YH Huang <yh.huang@mediatek.com>
> ---
>  drivers/pwm/Kconfig             |   9 ++
>  drivers/pwm/Makefile            |   1 +
>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 235 insertions(+)
>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index b1541f4..9edbb5a 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -111,6 +111,15 @@ config PWM_CLPS711X
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-clps711x.
>  
> +config PWM_DISP_MEDIATEK

Please make this "PWM_MEDIATEK_DISP" so we can keep everything sorted by
vendor.

> +	tristate "MEDIATEK display PWM driver"

"MediaTek"?

> +	depends on OF

Technically I think you need depends on HAS_IOMEM here to avoid breakage
on randconfig builds.

> +	help
> +	  Generic PWM framework driver for mediatek disp-pwm device.

"MediaTek"? Also perhaps this should describe what this PWM is instead
of just the "disp-pwm" which leaves everyone guessing what it is. From
the name I'd expect it to be the PWM that is used to control the
backlight brightness for display, but I think this description should
say that explicitly.

> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-disp-mediatek.

pwm-mediatek-disp

> +
>  config PWM_EP93XX
>  	tristate "Cirrus Logic EP93xx PWM support"
>  	depends on ARCH_EP93XX
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index ec50eb5..c5ff72a 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
>  obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
>  obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
>  obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
> +obj-$(CONFIG_PWM_DISP_MEDIATEK)	+= pwm-disp-mediatek.o

Also name this "pwm-mediatek-disp.o" to reflect the Kconfig name.

>  obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
>  obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
>  obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
> diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> new file mode 100644
> index 0000000..38293af
> --- /dev/null
> +++ b/drivers/pwm/pwm-disp-mediatek.c
> @@ -0,0 +1,225 @@
> +/*
> + * Mediatek display pulse-width-modulation controller driver.
> + * Copyright (c) 2015 MediaTek Inc.
> + * Author: YH Huang <yh.huang@mediatek.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define DISP_PWM_EN_OFF			(0x0)

The _OFF suffix here is unfortunate because I'm reading this as being
the "OFF" value for a field named "DISP_PWM_EN". I think it'd be better
to name this one DISP_PWM_EN. The same goes for any of the following
registers.

Also, drop the parentheses if the expression is simple.

> +#define PWM_ENABLE_SHIFT		(0x0)
> +#define PWM_ENABLE_MASK			(0x1 << PWM_ENABLE_SHIFT)
> +
> +#define DISP_PWM_COMMIT_OFF		(0x08)
> +#define PWM_COMMIT_SHIFT		(0x0)
> +#define PWM_COMMIT_MASK			(0x1 << PWM_COMMIT_SHIFT)
> +
> +#define DISP_PWM_CON_0_OFF		(0x10)
> +#define PWM_CLKDIV_SHIFT		(0x10)
> +#define PWM_CLKDIV_MASK			(0x3ff << PWM_CLKDIV_SHIFT)
> +#define PWM_CLKDIV_MAX			(0x000003ff)
> +
> +#define DISP_PWM_CON_1_OFF		(0x14)
> +#define PWM_PERIOD_SHIFT		(0x0)
> +#define PWM_PERIOD_MASK			(0xfff << PWM_PERIOD_SHIFT)
> +#define PWM_PERIOD_MAX			(0x00000fff)
> +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> +#define PWM_PERIOD_BIT_SHIFT		12

This is confusing, see below.

> +
> +#define PWM_HIGH_WIDTH_SHIFT		(0x10)
> +#define PWM_HIGH_WIDTH_MASK		(0x1fff << PWM_HIGH_WIDTH_SHIFT)
> +
> +#define NUM_PWM 1

You can drop this, it's only used once.

> +
> +struct mtk_disp_pwm_chip {
> +	struct pwm_chip	chip;
> +	struct device	*dev;
> +	struct clk	*clk_main;
> +	struct clk	*clk_mm;
> +	void __iomem	*mmio_base;
> +};

Please don't add this artificial padding, a single space is enough as a
separator. Also, I think you can drop the _chip suffix on the structure
name.

> +
> +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)

This is a bad name. I think you should adopt the naming of regmap, which
this effectively copies, so this should be:

	static void mtk_disp_pwm_update_bits(void __iomem *address, u32 mask, u32 value)

> +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> +			       int duty_ns, int period_ns)
> +{
> +	struct mtk_disp_pwm_chip *mpc;
> +	u64 div, rate;
> +	u32 clk_div, period, high_width, rem;
> +
> +	/*
> +	 * Find period, high_width and clk_div to suit duty_ns and period_ns.
> +	 * Calculate proper div value to keep period value in the bound.
> +	 *
> +	 * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> +	 * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> +	 *
> +	 * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> +	 * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> +	 */
> +	mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);

Can you add a static inline function to wrap the container_of()
invocation? You need to do this quite often and the wrapper will shorten
the code significantly:

	static inline struct mtk_disp_pwm *to_mtk_disp_pwm(struct pwm_chip *chip)
	{
		return container_of(chip, struct mtk_disp_pwm, chip);
	}

Also it's slightly more canonical to initialize the mpc variable as part
of the declaration.

> +	rate = clk_get_rate(mpc->clk_main);
> +	clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> +				PWM_PERIOD_BIT_SHIFT;
> +	if (clk_div > PWM_CLKDIV_MAX)
> +		return -EINVAL;
> +
> +	div = clk_div + 1;
> +	period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> +	if (period > 0)
> +		period--;
> +	high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> +	if (high_width > 0)
> +		high_width--;
> +
> +	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> +			     clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> +	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> +			     (period << PWM_PERIOD_SHIFT) |
> +			(high_width << PWM_HIGH_WIDTH_SHIFT),
> +			PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);

Can you align these differently to make it more readable?

	mtk_display_pwm_update_bits(mpc->mmio_base + DISP_PWM_CON_1,
				    PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK,
				    (period << PWM_PERIOD_SHIFT) |
					(high_width << PWM_HIGH_WIDTH_SHIFT));

Or perhaps split it into multiple steps to make it even more readable:

	value = (high_width << PWM_HIGH_WIDTH_SHIFT) |
		(period << PWM_PERIOD_SHIFT);
	mtk_display_pwm_update_bits(mpc->mmio_base + DISP_PWM_CON_1,
				    PWM_HIGH_WIDTH_MASK | PWM_PERIOD_MASK,
				    value);

> +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pwm;
> +	struct resource *r;
> +	int ret;
> +
> +	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> +	if (!pwm)
> +		return -ENOMEM;
> +
> +	pwm->dev = &pdev->dev;
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(pwm->mmio_base))
> +		return PTR_ERR(pwm->mmio_base);
> +
> +	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> +	if (IS_ERR(pwm->clk_main))
> +		return PTR_ERR(pwm->clk_main);
> +	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");

I think it's more readable if a blank line separates the above two
lines.

> +	if (IS_ERR(pwm->clk_mm))
> +		return PTR_ERR(pwm->clk_mm);
> +
> +	ret = clk_prepare_enable(pwm->clk_main);
> +	if (ret < 0)
> +		return ret;
> +	ret = clk_prepare_enable(pwm->clk_mm);

Same here.

> +	if (ret < 0) {
> +		clk_disable_unprepare(pwm->clk_main);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, pwm);
> +
> +	pwm->chip.dev = &pdev->dev;
> +	pwm->chip.ops = &mtk_disp_pwm_ops;
> +	pwm->chip.base = -1;
> +	pwm->chip.npwm = NUM_PWM;
> +
> +	ret = pwmchip_add(&pwm->chip);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);

Shouldn't you disable the clocks here?

> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> +{
> +	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> +
> +	if (WARN_ON(!pc))
> +		return -ENODEV;

You can drop this. Better to let it crash so that you have to fix it if
you ever encounter it.

> +
> +	clk_disable_unprepare(pc->clk_main);
> +	clk_disable_unprepare(pc->clk_mm);
> +
> +	return pwmchip_remove(&pc->chip);
> +}
> +
> +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> +	{ .compatible = "mediatek,mt6595-disp-pwm" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);

No blank line between the above two lines.

> +
> +static struct platform_driver mtk_disp_pwm_driver = {
> +	.driver = {
> +		.name = "mediatek-disp-pwm",
> +		.owner = THIS_MODULE,
> +		.of_match_table = mtk_disp_pwm_of_match,
> +	},
> +	.probe = mtk_disp_pwm_probe,
> +	.remove = mtk_disp_pwm_remove,
> +};
> +
> +module_platform_driver(mtk_disp_pwm_driver);

Same here. Also, no need to initialize .driver.owner,
module_platform_driver() does that for you.

Thierry
Matthias Brugger May 12, 2015, 2:34 p.m. UTC | #5
2015-05-12 15:32 GMT+02:00 Thierry Reding <thierry.reding@gmail.com>:
> On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
>> Add display PWM driver support to modify backlight for MT8173/MT6595.
>>
>> Signed-off-by: YH Huang <yh.huang@mediatek.com>
>> ---
>>  drivers/pwm/Kconfig             |   9 ++
>>  drivers/pwm/Makefile            |   1 +
>>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 235 insertions(+)
>>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
>>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index b1541f4..9edbb5a 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -111,6 +111,15 @@ config PWM_CLPS711X
>>         To compile this driver as a module, choose M here: the module
>>         will be called pwm-clps711x.
>>
>> +config PWM_DISP_MEDIATEK
>
> Please make this "PWM_MEDIATEK_DISP" so we can keep everything sorted by
> vendor.
>
>> +     tristate "MEDIATEK display PWM driver"
>
> "MediaTek"?
>
>> +     depends on OF
>
> Technically I think you need depends on HAS_IOMEM here to avoid breakage
> on randconfig builds.
>
>> +     help
>> +       Generic PWM framework driver for mediatek disp-pwm device.
>
> "MediaTek"? Also perhaps this should describe what this PWM is instead
> of just the "disp-pwm" which leaves everyone guessing what it is. From
> the name I'd expect it to be the PWM that is used to control the
> backlight brightness for display, but I think this description should
> say that explicitly.
>
>> +
>> +       To compile this driver as a module, choose M here: the module
>> +       will be called pwm-disp-mediatek.
>
> pwm-mediatek-disp

I would prefert pwm-mtk-disp which is in line with the other drivers.
Also I have to admit that unfortunately the naming is not uniformly
throughout the kernel.

Thanks,
Matthias
YH Huang May 14, 2015, 2:39 p.m. UTC | #6
On Tue, 2015-05-12 at 14:37 +0200, Matthias Brugger wrote:
> Hi YH,
> 
> 2015-05-11 11:26 GMT+02:00 YH Huang <yh.huang@mediatek.com>:
> > Add display PWM driver support to modify backlight for MT8173/MT6595.
> >
> > Signed-off-by: YH Huang <yh.huang@mediatek.com>
> > ---
> >  drivers/pwm/Kconfig             |   9 ++
> >  drivers/pwm/Makefile            |   1 +
> >  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 235 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> >
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index b1541f4..9edbb5a 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -111,6 +111,15 @@ config PWM_CLPS711X
> >           To compile this driver as a module, choose M here: the module
> >           will be called pwm-clps711x.
> >
> > +config PWM_DISP_MEDIATEK
> > +       tristate "MEDIATEK display PWM driver"
> > +       depends on OF
> > +       help
> > +         Generic PWM framework driver for mediatek disp-pwm device.
> > +
> > +         To compile this driver as a module, choose M here: the module
> > +         will be called pwm-disp-mediatek.
> > +
> >  config PWM_EP93XX
> >         tristate "Cirrus Logic EP93xx PWM support"
> >         depends on ARCH_EP93XX
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index ec50eb5..c5ff72a 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
> >  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
> >  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
> >  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> > +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
> >  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
> >  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
> >  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> > diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> > new file mode 100644
> > index 0000000..38293af
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-disp-mediatek.c
> > @@ -0,0 +1,225 @@
> > +/*
> > + * Mediatek display pulse-width-modulation controller driver.
> > + * Copyright (c) 2015 MediaTek Inc.
> > + * Author: YH Huang <yh.huang@mediatek.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/pwm.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#define DISP_PWM_EN_OFF                        (0x0)
> > +#define PWM_ENABLE_SHIFT               (0x0)
> > +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
> 
> Get rid of the _SHIFT which are actually zero, it will make the code
> more readable.
> 

It seems unnecessary to add it and I will fix it.

> > +
> > +#define DISP_PWM_COMMIT_OFF            (0x08)
> > +#define PWM_COMMIT_SHIFT               (0x0)
> > +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> > +
> > +#define DISP_PWM_CON_0_OFF             (0x10)
> > +#define PWM_CLKDIV_SHIFT               (0x10)
> > +#define PWM_CLKDIV_MASK                        (0x3ff << PWM_CLKDIV_SHIFT)
> > +#define PWM_CLKDIV_MAX                 (0x000003ff)
> > +
> > +#define DISP_PWM_CON_1_OFF             (0x14)
> > +#define PWM_PERIOD_SHIFT               (0x0)
> > +#define PWM_PERIOD_MASK                        (0xfff << PWM_PERIOD_SHIFT)
> > +#define PWM_PERIOD_MAX                 (0x00000fff)
> > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> > +#define PWM_PERIOD_BIT_SHIFT           12
> > +
> > +#define PWM_HIGH_WIDTH_SHIFT           (0x10)
> > +#define PWM_HIGH_WIDTH_MASK            (0x1fff << PWM_HIGH_WIDTH_SHIFT)
> > +
> > +#define NUM_PWM 1
> > +
> > +struct mtk_disp_pwm_chip {
> > +       struct pwm_chip chip;
> > +       struct device   *dev;
> > +       struct clk      *clk_main;
> > +       struct clk      *clk_mm;
> > +       void __iomem    *mmio_base;
> > +};
> > +
> > +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> > +{
> > +       u32 val;
> > +
> > +       val = readl(address);
> > +       val &= ~mask;
> > +       val |= value;
> > +       writel(val, address);
> > +}
> > +
> > +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > +                              int duty_ns, int period_ns)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +       u64 div, rate;
> > +       u32 clk_div, period, high_width, rem;
> > +
> > +       /*
> > +        * Find period, high_width and clk_div to suit duty_ns and period_ns.
> > +        * Calculate proper div value to keep period value in the bound.
> > +        *
> > +        * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> > +        * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> > +        *
> > +        * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> > +        * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> > +        */
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       rate = clk_get_rate(mpc->clk_main);
> > +       clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> > +                               PWM_PERIOD_BIT_SHIFT;
> 
> You never use the remainder, so better use div_u64 to make the code cleaner.
> 

OK.

> > +       if (clk_div > PWM_CLKDIV_MAX)
> > +               return -EINVAL;
> > +
> > +       div = clk_div + 1;
> > +       period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> > +       if (period > 0)
> > +               period--;
> > +       high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> > +       if (high_width > 0)
> > +               high_width--;
> > +
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> > +                            clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> > +                            (period << PWM_PERIOD_SHIFT) |
> > +                       (high_width << PWM_HIGH_WIDTH_SHIFT),
> > +                       PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> > +
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > +                            1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > +                            0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > +
> > +       return 0;
> > +}
> > +
> > +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > +                            1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > +
> > +       return 0;
> > +}
> > +
> > +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > +                            0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > +}
> > +
> > +static const struct pwm_ops mtk_disp_pwm_ops = {
> > +       .config = mtk_disp_pwm_config,
> > +       .enable = mtk_disp_pwm_enable,
> > +       .disable = mtk_disp_pwm_disable,
> > +       .owner = THIS_MODULE,
> > +};
> > +
> > +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> > +{
> > +       struct mtk_disp_pwm_chip *pwm;
> > +       struct resource *r;
> > +       int ret;
> > +
> > +       pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> > +       if (!pwm)
> > +               return -ENOMEM;
> > +
> > +       pwm->dev = &pdev->dev;
> > +
> > +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> > +       if (IS_ERR(pwm->mmio_base))
> > +               return PTR_ERR(pwm->mmio_base);
> > +
> > +       pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> > +       if (IS_ERR(pwm->clk_main))
> > +               return PTR_ERR(pwm->clk_main);
> 
> I prefer to have a newline after the if-then-ese block, which makes it
> (at least for me) easier to read the code.
> 

OK.

> Thanks,
> Matthias

Thank for your suggestion.

Regards,
YH Huang
YH Huang May 14, 2015, 2:45 p.m. UTC | #7
On Tue, 2015-05-12 at 14:44 +0200, Matthias Brugger wrote:
> 2015-05-12 14:37 GMT+02:00 Matthias Brugger <matthias.bgg@gmail.com>:
> > Hi YH,
> >
> > 2015-05-11 11:26 GMT+02:00 YH Huang <yh.huang@mediatek.com>:
> >> Add display PWM driver support to modify backlight for MT8173/MT6595.
> >>
> >> Signed-off-by: YH Huang <yh.huang@mediatek.com>
> >> ---
> >>  drivers/pwm/Kconfig             |   9 ++
> >>  drivers/pwm/Makefile            |   1 +
> >>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> >>  3 files changed, 235 insertions(+)
> >>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> >>
> >> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> >> index b1541f4..9edbb5a 100644
> >> --- a/drivers/pwm/Kconfig
> >> +++ b/drivers/pwm/Kconfig
> >> @@ -111,6 +111,15 @@ config PWM_CLPS711X
> >>           To compile this driver as a module, choose M here: the module
> >>           will be called pwm-clps711x.
> >>
> >> +config PWM_DISP_MEDIATEK
> >> +       tristate "MEDIATEK display PWM driver"
> >> +       depends on OF
> >> +       help
> >> +         Generic PWM framework driver for mediatek disp-pwm device.
> >> +
> >> +         To compile this driver as a module, choose M here: the module
> >> +         will be called pwm-disp-mediatek.
> >> +
> >>  config PWM_EP93XX
> >>         tristate "Cirrus Logic EP93xx PWM support"
> >>         depends on ARCH_EP93XX
> >> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> >> index ec50eb5..c5ff72a 100644
> >> --- a/drivers/pwm/Makefile
> >> +++ b/drivers/pwm/Makefile
> >> @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
> >>  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
> >>  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
> >>  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> >> +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
> >>  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
> >>  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
> >>  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> >> diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> >> new file mode 100644
> >> index 0000000..38293af
> >> --- /dev/null
> >> +++ b/drivers/pwm/pwm-disp-mediatek.c
> >> @@ -0,0 +1,225 @@
> >> +/*
> >> + * Mediatek display pulse-width-modulation controller driver.
> >> + * Copyright (c) 2015 MediaTek Inc.
> >> + * Author: YH Huang <yh.huang@mediatek.com>
> >> + *
> >> + * This program is free software; you can redistribute it and/or modify
> >> + * it under the terms of the GNU General Public License version 2 as
> >> + * published by the Free Software Foundation.
> >> + *
> >> + * This program is distributed in the hope that it will be useful,
> >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> >> + * GNU General Public License for more details.
> >> + */
> >> +
> >> +#include <linux/clk.h>
> >> +#include <linux/err.h>
> >> +#include <linux/io.h>
> >> +#include <linux/module.h>
> >> +#include <linux/of.h>
> >> +#include <linux/pwm.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/slab.h>
> >> +
> >> +#define DISP_PWM_EN_OFF                        (0x0)
> >> +#define PWM_ENABLE_SHIFT               (0x0)
> >> +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
> >
> > Get rid of the _SHIFT which are actually zero, it will make the code
> > more readable.
> >
> >> +
> >> +#define DISP_PWM_COMMIT_OFF            (0x08)
> >> +#define PWM_COMMIT_SHIFT               (0x0)
> >> +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> >> +
> >> +#define DISP_PWM_CON_0_OFF             (0x10)
> >> +#define PWM_CLKDIV_SHIFT               (0x10)
> 
> I prefer to have the shift values in decimal instead of hex, as it
> makes it easier to see which bits in the registers are the relevant
> ones.
> Sorry forgot that one.
> 

I think you are right.

> Cheers,
> Matthias

Thank for your suggestion.

Regards,
YH Huang
YH Huang May 14, 2015, 2:52 p.m. UTC | #8
On Tue, 2015-05-12 at 15:00 +0200, Sascha Hauer wrote:
> On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> > +
> > +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> > +{
> > +	struct mtk_disp_pwm_chip *pwm;
> 
> The struct mtk_disp_pwm_chip * is named 'mpc' in the other functions.
> For consistency reasons you should do that here aswell.
> 

I miss it! Maybe 'mdpc' is a better name for mtk_disp_pwm_chip.

> > +	struct resource *r;
> > +	int ret;
> > +
> > +	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> > +	if (!pwm)
> > +		return -ENOMEM;
> > +
> > +	pwm->dev = &pdev->dev;
> > +
> > +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> > +	if (IS_ERR(pwm->mmio_base))
> > +		return PTR_ERR(pwm->mmio_base);
> > +
> > +	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> > +	if (IS_ERR(pwm->clk_main))
> > +		return PTR_ERR(pwm->clk_main);
> > +	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> > +	if (IS_ERR(pwm->clk_mm))
> > +		return PTR_ERR(pwm->clk_mm);
> > +
> > +	ret = clk_prepare_enable(pwm->clk_main);
> > +	if (ret < 0)
> > +		return ret;
> > +	ret = clk_prepare_enable(pwm->clk_mm);
> > +	if (ret < 0) {
> > +		clk_disable_unprepare(pwm->clk_main);
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, pwm);
> > +
> > +	pwm->chip.dev = &pdev->dev;
> > +	pwm->chip.ops = &mtk_disp_pwm_ops;
> > +	pwm->chip.base = -1;
> > +	pwm->chip.npwm = NUM_PWM;
> > +
> > +	ret = pwmchip_add(&pwm->chip);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> > +		return ret;
> 
> This error path leaves the clocks enabled.
> 

I forgot this one. I will fix it.

> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> > +{
> > +	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> > +
> > +	if (WARN_ON(!pc))
> > +		return -ENODEV;
> > +
> > +	clk_disable_unprepare(pc->clk_main);
> > +	clk_disable_unprepare(pc->clk_mm);
> > +
> > +	return pwmchip_remove(&pc->chip);
> 
> You should first remove the pwmchip and disable the clocks afterwards.
> Also note that this function can fail.
> 

OK.

> Sascha
> 

Thank for your suggestion.

Regards,
YH Huang
YH Huang May 14, 2015, 3:35 p.m. UTC | #9
On Tue, 2015-05-12 at 15:32 +0200, Thierry Reding wrote:
> On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> > Add display PWM driver support to modify backlight for MT8173/MT6595.
> > 
> > Signed-off-by: YH Huang <yh.huang@mediatek.com>
> > ---
> >  drivers/pwm/Kconfig             |   9 ++
> >  drivers/pwm/Makefile            |   1 +
> >  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 235 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> > 
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index b1541f4..9edbb5a 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -111,6 +111,15 @@ config PWM_CLPS711X
> >  	  To compile this driver as a module, choose M here: the module
> >  	  will be called pwm-clps711x.
> >  
> > +config PWM_DISP_MEDIATEK
> 
> Please make this "PWM_MEDIATEK_DISP" so we can keep everything sorted by
> vendor.
> 

Probably "PWM_MTK_DSIP" for Matthias opinion?

> > +	tristate "MEDIATEK display PWM driver"
> 
> "MediaTek"?
> 

OK.

> > +	depends on OF
> 
> Technically I think you need depends on HAS_IOMEM here to avoid breakage
> on randconfig builds.
> 

OK.

> > +	help
> > +	  Generic PWM framework driver for mediatek disp-pwm device.
> 
> "MediaTek"? Also perhaps this should describe what this PWM is instead
> of just the "disp-pwm" which leaves everyone guessing what it is. From
> the name I'd expect it to be the PWM that is used to control the
> backlight brightness for display, but I think this description should
> say that explicitly.
> 
> > +
> > +	  To compile this driver as a module, choose M here: the module
> > +	  will be called pwm-disp-mediatek.
> 
> pwm-mediatek-disp

pwm-mtk-disp?

> 
> > +
> >  config PWM_EP93XX
> >  	tristate "Cirrus Logic EP93xx PWM support"
> >  	depends on ARCH_EP93XX
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index ec50eb5..c5ff72a 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
> >  obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
> >  obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
> >  obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
> > +obj-$(CONFIG_PWM_DISP_MEDIATEK)	+= pwm-disp-mediatek.o
> 
> Also name this "pwm-mediatek-disp.o" to reflect the Kconfig name.

pwm-mtk-disp.o?

> 
> >  obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
> >  obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
> >  obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
> > diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> > new file mode 100644
> > index 0000000..38293af
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-disp-mediatek.c
> > @@ -0,0 +1,225 @@
> > +/*
> > + * Mediatek display pulse-width-modulation controller driver.
> > + * Copyright (c) 2015 MediaTek Inc.
> > + * Author: YH Huang <yh.huang@mediatek.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/pwm.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#define DISP_PWM_EN_OFF			(0x0)
> 
> The _OFF suffix here is unfortunate because I'm reading this as being
> the "OFF" value for a field named "DISP_PWM_EN". I think it'd be better
> to name this one DISP_PWM_EN. The same goes for any of the following
> registers.
> 
> Also, drop the parentheses if the expression is simple.

OK. It is really confusing.

> 
> > +#define PWM_ENABLE_SHIFT		(0x0)
> > +#define PWM_ENABLE_MASK			(0x1 << PWM_ENABLE_SHIFT)
> > +
> > +#define DISP_PWM_COMMIT_OFF		(0x08)
> > +#define PWM_COMMIT_SHIFT		(0x0)
> > +#define PWM_COMMIT_MASK			(0x1 << PWM_COMMIT_SHIFT)
> > +
> > +#define DISP_PWM_CON_0_OFF		(0x10)
> > +#define PWM_CLKDIV_SHIFT		(0x10)
> > +#define PWM_CLKDIV_MASK			(0x3ff << PWM_CLKDIV_SHIFT)
> > +#define PWM_CLKDIV_MAX			(0x000003ff)
> > +
> > +#define DISP_PWM_CON_1_OFF		(0x14)
> > +#define PWM_PERIOD_SHIFT		(0x0)
> > +#define PWM_PERIOD_MASK			(0xfff << PWM_PERIOD_SHIFT)
> > +#define PWM_PERIOD_MAX			(0x00000fff)
> > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> > +#define PWM_PERIOD_BIT_SHIFT		12
> 
> This is confusing, see below.

I don't really understand what does this mean.
Please help me.

> 
> > +
> > +#define PWM_HIGH_WIDTH_SHIFT		(0x10)
> > +#define PWM_HIGH_WIDTH_MASK		(0x1fff << PWM_HIGH_WIDTH_SHIFT)
> > +
> > +#define NUM_PWM 1
> 
> You can drop this, it's only used once.
> 

OK.

> > +
> > +struct mtk_disp_pwm_chip {
> > +	struct pwm_chip	chip;
> > +	struct device	*dev;
> > +	struct clk	*clk_main;
> > +	struct clk	*clk_mm;
> > +	void __iomem	*mmio_base;
> > +};
> 
> Please don't add this artificial padding, a single space is enough as a
> separator. Also, I think you can drop the _chip suffix on the structure
> name.
> 

OK.

> > +
> > +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> 
> This is a bad name. I think you should adopt the naming of regmap, which
> this effectively copies, so this should be:
> 
> 	static void mtk_disp_pwm_update_bits(void __iomem *address, u32 mask, u32 value)
> 

It is much readable.

> > +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > +			       int duty_ns, int period_ns)
> > +{
> > +	struct mtk_disp_pwm_chip *mpc;
> > +	u64 div, rate;
> > +	u32 clk_div, period, high_width, rem;
> > +
> > +	/*
> > +	 * Find period, high_width and clk_div to suit duty_ns and period_ns.
> > +	 * Calculate proper div value to keep period value in the bound.
> > +	 *
> > +	 * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> > +	 * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> > +	 *
> > +	 * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> > +	 * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> > +	 */
> > +	mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> 
> Can you add a static inline function to wrap the container_of()
> invocation? You need to do this quite often and the wrapper will shorten
> the code significantly:
> 
> 	static inline struct mtk_disp_pwm *to_mtk_disp_pwm(struct pwm_chip *chip)
> 	{
> 		return container_of(chip, struct mtk_disp_pwm, chip);
> 	}
> 
> Also it's slightly more canonical to initialize the mpc variable as part
> of the declaration.
> 

This is a good way to shorten the code.

> > +	rate = clk_get_rate(mpc->clk_main);
> > +	clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> > +				PWM_PERIOD_BIT_SHIFT;
> > +	if (clk_div > PWM_CLKDIV_MAX)
> > +		return -EINVAL;
> > +
> > +	div = clk_div + 1;
> > +	period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> > +	if (period > 0)
> > +		period--;
> > +	high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> > +	if (high_width > 0)
> > +		high_width--;
> > +
> > +	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> > +			     clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> > +	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> > +			     (period << PWM_PERIOD_SHIFT) |
> > +			(high_width << PWM_HIGH_WIDTH_SHIFT),
> > +			PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> 
> Can you align these differently to make it more readable?
> 
> 	mtk_display_pwm_update_bits(mpc->mmio_base + DISP_PWM_CON_1,
> 				    PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK,
> 				    (period << PWM_PERIOD_SHIFT) |
> 					(high_width << PWM_HIGH_WIDTH_SHIFT));
> 
> Or perhaps split it into multiple steps to make it even more readable:
> 
> 	value = (high_width << PWM_HIGH_WIDTH_SHIFT) |
> 		(period << PWM_PERIOD_SHIFT);
> 	mtk_display_pwm_update_bits(mpc->mmio_base + DISP_PWM_CON_1,
> 				    PWM_HIGH_WIDTH_MASK | PWM_PERIOD_MASK,
> 				    value);
> 

OK, it is really hard to read.

> > +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> > +{
> > +	struct mtk_disp_pwm_chip *pwm;
> > +	struct resource *r;
> > +	int ret;
> > +
> > +	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> > +	if (!pwm)
> > +		return -ENOMEM;
> > +
> > +	pwm->dev = &pdev->dev;
> > +
> > +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> > +	if (IS_ERR(pwm->mmio_base))
> > +		return PTR_ERR(pwm->mmio_base);
> > +
> > +	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> > +	if (IS_ERR(pwm->clk_main))
> > +		return PTR_ERR(pwm->clk_main);
> > +	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> 
> I think it's more readable if a blank line separates the above two
> lines.

OK.

> 
> > +	if (IS_ERR(pwm->clk_mm))
> > +		return PTR_ERR(pwm->clk_mm);
> > +
> > +	ret = clk_prepare_enable(pwm->clk_main);
> > +	if (ret < 0)
> > +		return ret;
> > +	ret = clk_prepare_enable(pwm->clk_mm);
> 
> Same here.

OK.

> 
> > +	if (ret < 0) {
> > +		clk_disable_unprepare(pwm->clk_main);
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, pwm);
> > +
> > +	pwm->chip.dev = &pdev->dev;
> > +	pwm->chip.ops = &mtk_disp_pwm_ops;
> > +	pwm->chip.base = -1;
> > +	pwm->chip.npwm = NUM_PWM;
> > +
> > +	ret = pwmchip_add(&pwm->chip);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> 
> Shouldn't you disable the clocks here?

I will fix it.

> 
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> > +{
> > +	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> > +
> > +	if (WARN_ON(!pc))
> > +		return -ENODEV;
> 
> You can drop this. Better to let it crash so that you have to fix it if
> you ever encounter it.

I will think about it.

> 
> > +
> > +	clk_disable_unprepare(pc->clk_main);
> > +	clk_disable_unprepare(pc->clk_mm);
> > +
> > +	return pwmchip_remove(&pc->chip);
> > +}
> > +
> > +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> > +	{ .compatible = "mediatek,mt6595-disp-pwm" },
> > +	{ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
> 
> No blank line between the above two lines.

OK.

> 
> > +
> > +static struct platform_driver mtk_disp_pwm_driver = {
> > +	.driver = {
> > +		.name = "mediatek-disp-pwm",
> > +		.owner = THIS_MODULE,
> > +		.of_match_table = mtk_disp_pwm_of_match,
> > +	},
> > +	.probe = mtk_disp_pwm_probe,
> > +	.remove = mtk_disp_pwm_remove,
> > +};
> > +
> > +module_platform_driver(mtk_disp_pwm_driver);
> 
> Same here. Also, no need to initialize .driver.owner,
> module_platform_driver() does that for you.

Got it.

> 
> Thierry


Thank for your suggestion.

Regards,
YH Huang
YH Huang May 14, 2015, 3:39 p.m. UTC | #10
On Tue, 2015-05-12 at 16:34 +0200, Matthias Brugger wrote:
> 2015-05-12 15:32 GMT+02:00 Thierry Reding <thierry.reding@gmail.com>:
> > On Mon, May 11, 2015 at 05:26:22PM +0800, YH Huang wrote:
> >> Add display PWM driver support to modify backlight for MT8173/MT6595.
> >>
> >> Signed-off-by: YH Huang <yh.huang@mediatek.com>
> >> ---
> >>  drivers/pwm/Kconfig             |   9 ++
> >>  drivers/pwm/Makefile            |   1 +
> >>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> >>  3 files changed, 235 insertions(+)
> >>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> >>
> >> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> >> index b1541f4..9edbb5a 100644
> >> --- a/drivers/pwm/Kconfig
> >> +++ b/drivers/pwm/Kconfig
> >> @@ -111,6 +111,15 @@ config PWM_CLPS711X
> >>         To compile this driver as a module, choose M here: the module
> >>         will be called pwm-clps711x.
> >>
> >> +config PWM_DISP_MEDIATEK
> >
> > Please make this "PWM_MEDIATEK_DISP" so we can keep everything sorted by
> > vendor.
> >
> >> +     tristate "MEDIATEK display PWM driver"
> >
> > "MediaTek"?
> >
> >> +     depends on OF
> >
> > Technically I think you need depends on HAS_IOMEM here to avoid breakage
> > on randconfig builds.
> >
> >> +     help
> >> +       Generic PWM framework driver for mediatek disp-pwm device.
> >
> > "MediaTek"? Also perhaps this should describe what this PWM is instead
> > of just the "disp-pwm" which leaves everyone guessing what it is. From
> > the name I'd expect it to be the PWM that is used to control the
> > backlight brightness for display, but I think this description should
> > say that explicitly.
> >
> >> +
> >> +       To compile this driver as a module, choose M here: the module
> >> +       will be called pwm-disp-mediatek.
> >
> > pwm-mediatek-disp
> 
> I would prefert pwm-mtk-disp which is in line with the other drivers.
> Also I have to admit that unfortunately the naming is not uniformly
> throughout the kernel.
> 

OK. I will take it.

> Thanks,
> Matthias

Thank for your suggestion.

Regards,
YH Huang
Daniel Kurtz May 18, 2015, 3:42 a.m. UTC | #11
On Mon, May 11, 2015 at 5:26 PM, YH Huang <yh.huang@mediatek.com> wrote:
> Add display PWM driver support to modify backlight for MT8173/MT6595.
>
> Signed-off-by: YH Huang <yh.huang@mediatek.com>
> ---
>  drivers/pwm/Kconfig             |   9 ++
>  drivers/pwm/Makefile            |   1 +
>  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 235 insertions(+)
>  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index b1541f4..9edbb5a 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -111,6 +111,15 @@ config PWM_CLPS711X
>           To compile this driver as a module, choose M here: the module
>           will be called pwm-clps711x.
>
> +config PWM_DISP_MEDIATEK
> +       tristate "MEDIATEK display PWM driver"
> +       depends on OF
> +       help
> +         Generic PWM framework driver for mediatek disp-pwm device.
> +
> +         To compile this driver as a module, choose M here: the module
> +         will be called pwm-disp-mediatek.
> +
>  config PWM_EP93XX
>         tristate "Cirrus Logic EP93xx PWM support"
>         depends on ARCH_EP93XX
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index ec50eb5..c5ff72a 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
>  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
>  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
>  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
>  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
>  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
>  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> new file mode 100644
> index 0000000..38293af
> --- /dev/null
> +++ b/drivers/pwm/pwm-disp-mediatek.c
> @@ -0,0 +1,225 @@
> +/*
> + * Mediatek display pulse-width-modulation controller driver.
> + * Copyright (c) 2015 MediaTek Inc.
> + * Author: YH Huang <yh.huang@mediatek.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define DISP_PWM_EN_OFF                        (0x0)
> +#define PWM_ENABLE_SHIFT               (0x0)
> +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
> +
> +#define DISP_PWM_COMMIT_OFF            (0x08)
> +#define PWM_COMMIT_SHIFT               (0x0)
> +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> +
> +#define DISP_PWM_CON_0_OFF             (0x10)
> +#define PWM_CLKDIV_SHIFT               (0x10)
> +#define PWM_CLKDIV_MASK                        (0x3ff << PWM_CLKDIV_SHIFT)
> +#define PWM_CLKDIV_MAX                 (0x000003ff)
> +
> +#define DISP_PWM_CON_1_OFF             (0x14)
> +#define PWM_PERIOD_SHIFT               (0x0)
> +#define PWM_PERIOD_MASK                        (0xfff << PWM_PERIOD_SHIFT)
> +#define PWM_PERIOD_MAX                 (0x00000fff)
> +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> +#define PWM_PERIOD_BIT_SHIFT           12
> +
> +#define PWM_HIGH_WIDTH_SHIFT           (0x10)
> +#define PWM_HIGH_WIDTH_MASK            (0x1fff << PWM_HIGH_WIDTH_SHIFT)
> +
> +#define NUM_PWM 1
> +
> +struct mtk_disp_pwm_chip {
> +       struct pwm_chip chip;
> +       struct device   *dev;
> +       struct clk      *clk_main;
> +       struct clk      *clk_mm;
> +       void __iomem    *mmio_base;
> +};
> +
> +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> +{
> +       u32 val;
> +
> +       val = readl(address);
> +       val &= ~mask;
> +       val |= value;
> +       writel(val, address);
> +}
> +
> +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> +                              int duty_ns, int period_ns)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +       u64 div, rate;
> +       u32 clk_div, period, high_width, rem;
> +
> +       /*
> +        * Find period, high_width and clk_div to suit duty_ns and period_ns.
> +        * Calculate proper div value to keep period value in the bound.
> +        *
> +        * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> +        * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> +        *
> +        * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> +        * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> +        */
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       rate = clk_get_rate(mpc->clk_main);
> +       clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> +                               PWM_PERIOD_BIT_SHIFT;
> +       if (clk_div > PWM_CLKDIV_MAX)
> +               return -EINVAL;
> +
> +       div = clk_div + 1;
> +       period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> +       if (period > 0)
> +               period--;
> +       high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> +       if (high_width > 0)
> +               high_width--;
> +
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> +                            clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> +                            (period << PWM_PERIOD_SHIFT) |
> +                       (high_width << PWM_HIGH_WIDTH_SHIFT),
> +                       PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> +
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> +                            1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> +                            0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> +
> +       return 0;
> +}
> +
> +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> +                            1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> +
> +       return 0;
> +}
> +
> +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +       struct mtk_disp_pwm_chip *mpc;
> +
> +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> +                            0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> +}
> +
> +static const struct pwm_ops mtk_disp_pwm_ops = {
> +       .config = mtk_disp_pwm_config,
> +       .enable = mtk_disp_pwm_enable,
> +       .disable = mtk_disp_pwm_disable,
> +       .owner = THIS_MODULE,
> +};
> +
> +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> +{
> +       struct mtk_disp_pwm_chip *pwm;
> +       struct resource *r;
> +       int ret;
> +
> +       pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> +       if (!pwm)
> +               return -ENOMEM;
> +
> +       pwm->dev = &pdev->dev;
> +
> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> +       if (IS_ERR(pwm->mmio_base))
> +               return PTR_ERR(pwm->mmio_base);
> +
> +       pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> +       if (IS_ERR(pwm->clk_main))
> +               return PTR_ERR(pwm->clk_main);
> +       pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> +       if (IS_ERR(pwm->clk_mm))
> +               return PTR_ERR(pwm->clk_mm);
> +
> +       ret = clk_prepare_enable(pwm->clk_main);
> +       if (ret < 0)
> +               return ret;
> +       ret = clk_prepare_enable(pwm->clk_mm);
> +       if (ret < 0) {
> +               clk_disable_unprepare(pwm->clk_main);
> +               return ret;
> +       }
> +
> +       platform_set_drvdata(pdev, pwm);
> +
> +       pwm->chip.dev = &pdev->dev;
> +       pwm->chip.ops = &mtk_disp_pwm_ops;
> +       pwm->chip.base = -1;
> +       pwm->chip.npwm = NUM_PWM;
> +
> +       ret = pwmchip_add(&pwm->chip);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> +{
> +       struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> +
> +       if (WARN_ON(!pc))
> +               return -ENODEV;
> +
> +       clk_disable_unprepare(pc->clk_main);
> +       clk_disable_unprepare(pc->clk_mm);
> +
> +       return pwmchip_remove(&pc->chip);
> +}
> +
> +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> +       { .compatible = "mediatek,mt6595-disp-pwm" },

Does this driver support the PWM in mt8173?
If so, don't you need this, too:

  { .compatible = "mediatek,mt8173-disp-pwm" },

> +       { }
> +};
> +
> +MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
> +
> +static struct platform_driver mtk_disp_pwm_driver = {
> +       .driver = {
> +               .name = "mediatek-disp-pwm",
> +               .owner = THIS_MODULE,
> +               .of_match_table = mtk_disp_pwm_of_match,
> +       },
> +       .probe = mtk_disp_pwm_probe,
> +       .remove = mtk_disp_pwm_remove,
> +};
> +
> +module_platform_driver(mtk_disp_pwm_driver);
> +
> +MODULE_AUTHOR("YH Huang <yh.huang@mediatek.com>");
> +MODULE_DESCRIPTION("MediaTek SoC display PWM driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.8.1.1.dirty
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
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> Please read the FAQ at  http://www.tux.org/lkml/
YH Huang May 21, 2015, 8:22 a.m. UTC | #12
On Mon, 2015-05-18 at 11:42 +0800, Daniel Kurtz wrote:
> On Mon, May 11, 2015 at 5:26 PM, YH Huang <yh.huang@mediatek.com> wrote:
> > Add display PWM driver support to modify backlight for MT8173/MT6595.
> >
> > Signed-off-by: YH Huang <yh.huang@mediatek.com>
> > ---
> >  drivers/pwm/Kconfig             |   9 ++
> >  drivers/pwm/Makefile            |   1 +
> >  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 235 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> >
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index b1541f4..9edbb5a 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -111,6 +111,15 @@ config PWM_CLPS711X
> >           To compile this driver as a module, choose M here: the module
> >           will be called pwm-clps711x.
> >
> > +config PWM_DISP_MEDIATEK
> > +       tristate "MEDIATEK display PWM driver"
> > +       depends on OF
> > +       help
> > +         Generic PWM framework driver for mediatek disp-pwm device.
> > +
> > +         To compile this driver as a module, choose M here: the module
> > +         will be called pwm-disp-mediatek.
> > +
> >  config PWM_EP93XX
> >         tristate "Cirrus Logic EP93xx PWM support"
> >         depends on ARCH_EP93XX
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index ec50eb5..c5ff72a 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
> >  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
> >  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
> >  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> > +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
> >  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
> >  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
> >  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> > diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> > new file mode 100644
> > index 0000000..38293af
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-disp-mediatek.c
> > @@ -0,0 +1,225 @@
> > +/*
> > + * Mediatek display pulse-width-modulation controller driver.
> > + * Copyright (c) 2015 MediaTek Inc.
> > + * Author: YH Huang <yh.huang@mediatek.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/pwm.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#define DISP_PWM_EN_OFF                        (0x0)
> > +#define PWM_ENABLE_SHIFT               (0x0)
> > +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
> > +
> > +#define DISP_PWM_COMMIT_OFF            (0x08)
> > +#define PWM_COMMIT_SHIFT               (0x0)
> > +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> > +
> > +#define DISP_PWM_CON_0_OFF             (0x10)
> > +#define PWM_CLKDIV_SHIFT               (0x10)
> > +#define PWM_CLKDIV_MASK                        (0x3ff << PWM_CLKDIV_SHIFT)
> > +#define PWM_CLKDIV_MAX                 (0x000003ff)
> > +
> > +#define DISP_PWM_CON_1_OFF             (0x14)
> > +#define PWM_PERIOD_SHIFT               (0x0)
> > +#define PWM_PERIOD_MASK                        (0xfff << PWM_PERIOD_SHIFT)
> > +#define PWM_PERIOD_MAX                 (0x00000fff)
> > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> > +#define PWM_PERIOD_BIT_SHIFT           12
> > +
> > +#define PWM_HIGH_WIDTH_SHIFT           (0x10)
> > +#define PWM_HIGH_WIDTH_MASK            (0x1fff << PWM_HIGH_WIDTH_SHIFT)
> > +
> > +#define NUM_PWM 1
> > +
> > +struct mtk_disp_pwm_chip {
> > +       struct pwm_chip chip;
> > +       struct device   *dev;
> > +       struct clk      *clk_main;
> > +       struct clk      *clk_mm;
> > +       void __iomem    *mmio_base;
> > +};
> > +
> > +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> > +{
> > +       u32 val;
> > +
> > +       val = readl(address);
> > +       val &= ~mask;
> > +       val |= value;
> > +       writel(val, address);
> > +}
> > +
> > +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > +                              int duty_ns, int period_ns)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +       u64 div, rate;
> > +       u32 clk_div, period, high_width, rem;
> > +
> > +       /*
> > +        * Find period, high_width and clk_div to suit duty_ns and period_ns.
> > +        * Calculate proper div value to keep period value in the bound.
> > +        *
> > +        * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> > +        * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> > +        *
> > +        * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> > +        * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> > +        */
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       rate = clk_get_rate(mpc->clk_main);
> > +       clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> > +                               PWM_PERIOD_BIT_SHIFT;
> > +       if (clk_div > PWM_CLKDIV_MAX)
> > +               return -EINVAL;
> > +
> > +       div = clk_div + 1;
> > +       period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> > +       if (period > 0)
> > +               period--;
> > +       high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> > +       if (high_width > 0)
> > +               high_width--;
> > +
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> > +                            clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> > +                            (period << PWM_PERIOD_SHIFT) |
> > +                       (high_width << PWM_HIGH_WIDTH_SHIFT),
> > +                       PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> > +
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > +                            1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > +                            0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > +
> > +       return 0;
> > +}
> > +
> > +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > +                            1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > +
> > +       return 0;
> > +}
> > +
> > +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +       struct mtk_disp_pwm_chip *mpc;
> > +
> > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > +                            0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > +}
> > +
> > +static const struct pwm_ops mtk_disp_pwm_ops = {
> > +       .config = mtk_disp_pwm_config,
> > +       .enable = mtk_disp_pwm_enable,
> > +       .disable = mtk_disp_pwm_disable,
> > +       .owner = THIS_MODULE,
> > +};
> > +
> > +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> > +{
> > +       struct mtk_disp_pwm_chip *pwm;
> > +       struct resource *r;
> > +       int ret;
> > +
> > +       pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> > +       if (!pwm)
> > +               return -ENOMEM;
> > +
> > +       pwm->dev = &pdev->dev;
> > +
> > +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> > +       if (IS_ERR(pwm->mmio_base))
> > +               return PTR_ERR(pwm->mmio_base);
> > +
> > +       pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> > +       if (IS_ERR(pwm->clk_main))
> > +               return PTR_ERR(pwm->clk_main);
> > +       pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> > +       if (IS_ERR(pwm->clk_mm))
> > +               return PTR_ERR(pwm->clk_mm);
> > +
> > +       ret = clk_prepare_enable(pwm->clk_main);
> > +       if (ret < 0)
> > +               return ret;
> > +       ret = clk_prepare_enable(pwm->clk_mm);
> > +       if (ret < 0) {
> > +               clk_disable_unprepare(pwm->clk_main);
> > +               return ret;
> > +       }
> > +
> > +       platform_set_drvdata(pdev, pwm);
> > +
> > +       pwm->chip.dev = &pdev->dev;
> > +       pwm->chip.ops = &mtk_disp_pwm_ops;
> > +       pwm->chip.base = -1;
> > +       pwm->chip.npwm = NUM_PWM;
> > +
> > +       ret = pwmchip_add(&pwm->chip);
> > +       if (ret < 0) {
> > +               dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> > +{
> > +       struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> > +
> > +       if (WARN_ON(!pc))
> > +               return -ENODEV;
> > +
> > +       clk_disable_unprepare(pc->clk_main);
> > +       clk_disable_unprepare(pc->clk_mm);
> > +
> > +       return pwmchip_remove(&pc->chip);
> > +}
> > +
> > +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> > +       { .compatible = "mediatek,mt6595-disp-pwm" },
> 
> Does this driver support the PWM in mt8173?
> If so, don't you need this, too:
> 
>   { .compatible = "mediatek,mt8173-disp-pwm" },

Yes, it supports mt8173.
I will add it.

> 
> > +       { }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
> > +
> > +static struct platform_driver mtk_disp_pwm_driver = {
> > +       .driver = {
> > +               .name = "mediatek-disp-pwm",
> > +               .owner = THIS_MODULE,
> > +               .of_match_table = mtk_disp_pwm_of_match,
> > +       },
> > +       .probe = mtk_disp_pwm_probe,
> > +       .remove = mtk_disp_pwm_remove,
> > +};
> > +
> > +module_platform_driver(mtk_disp_pwm_driver);
> > +
> > +MODULE_AUTHOR("YH Huang <yh.huang@mediatek.com>");
> > +MODULE_DESCRIPTION("MediaTek SoC display PWM driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 1.8.1.1.dirty
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/

Thank for your suggestion.

Regards,
YH Huang
Sascha Hauer May 26, 2015, 6:05 a.m. UTC | #13
On Thu, May 21, 2015 at 04:22:31PM +0800, YH Huang wrote:
> On Mon, 2015-05-18 at 11:42 +0800, Daniel Kurtz wrote:
> > On Mon, May 11, 2015 at 5:26 PM, YH Huang <yh.huang@mediatek.com> wrote:
> > > Add display PWM driver support to modify backlight for MT8173/MT6595.
> > >
> > > Signed-off-by: YH Huang <yh.huang@mediatek.com>
> > > ---
> > >  drivers/pwm/Kconfig             |   9 ++
> > >  drivers/pwm/Makefile            |   1 +
> > >  drivers/pwm/pwm-disp-mediatek.c | 225 ++++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 235 insertions(+)
> > >  create mode 100644 drivers/pwm/pwm-disp-mediatek.c
> > >
> > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > > index b1541f4..9edbb5a 100644
> > > --- a/drivers/pwm/Kconfig
> > > +++ b/drivers/pwm/Kconfig
> > > @@ -111,6 +111,15 @@ config PWM_CLPS711X
> > >           To compile this driver as a module, choose M here: the module
> > >           will be called pwm-clps711x.
> > >
> > > +config PWM_DISP_MEDIATEK
> > > +       tristate "MEDIATEK display PWM driver"
> > > +       depends on OF
> > > +       help
> > > +         Generic PWM framework driver for mediatek disp-pwm device.
> > > +
> > > +         To compile this driver as a module, choose M here: the module
> > > +         will be called pwm-disp-mediatek.
> > > +
> > >  config PWM_EP93XX
> > >         tristate "Cirrus Logic EP93xx PWM support"
> > >         depends on ARCH_EP93XX
> > > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > > index ec50eb5..c5ff72a 100644
> > > --- a/drivers/pwm/Makefile
> > > +++ b/drivers/pwm/Makefile
> > > @@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)      += pwm-bcm-kona.o
> > >  obj-$(CONFIG_PWM_BCM2835)      += pwm-bcm2835.o
> > >  obj-$(CONFIG_PWM_BFIN)         += pwm-bfin.o
> > >  obj-$(CONFIG_PWM_CLPS711X)     += pwm-clps711x.o
> > > +obj-$(CONFIG_PWM_DISP_MEDIATEK)        += pwm-disp-mediatek.o
> > >  obj-$(CONFIG_PWM_EP93XX)       += pwm-ep93xx.o
> > >  obj-$(CONFIG_PWM_FSL_FTM)      += pwm-fsl-ftm.o
> > >  obj-$(CONFIG_PWM_IMG)          += pwm-img.o
> > > diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
> > > new file mode 100644
> > > index 0000000..38293af
> > > --- /dev/null
> > > +++ b/drivers/pwm/pwm-disp-mediatek.c
> > > @@ -0,0 +1,225 @@
> > > +/*
> > > + * Mediatek display pulse-width-modulation controller driver.
> > > + * Copyright (c) 2015 MediaTek Inc.
> > > + * Author: YH Huang <yh.huang@mediatek.com>
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License version 2 as
> > > + * published by the Free Software Foundation.
> > > + *
> > > + * This program is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > + * GNU General Public License for more details.
> > > + */
> > > +
> > > +#include <linux/clk.h>
> > > +#include <linux/err.h>
> > > +#include <linux/io.h>
> > > +#include <linux/module.h>
> > > +#include <linux/of.h>
> > > +#include <linux/pwm.h>
> > > +#include <linux/platform_device.h>
> > > +#include <linux/slab.h>
> > > +
> > > +#define DISP_PWM_EN_OFF                        (0x0)
> > > +#define PWM_ENABLE_SHIFT               (0x0)
> > > +#define PWM_ENABLE_MASK                        (0x1 << PWM_ENABLE_SHIFT)
> > > +
> > > +#define DISP_PWM_COMMIT_OFF            (0x08)
> > > +#define PWM_COMMIT_SHIFT               (0x0)
> > > +#define PWM_COMMIT_MASK                        (0x1 << PWM_COMMIT_SHIFT)
> > > +
> > > +#define DISP_PWM_CON_0_OFF             (0x10)
> > > +#define PWM_CLKDIV_SHIFT               (0x10)
> > > +#define PWM_CLKDIV_MASK                        (0x3ff << PWM_CLKDIV_SHIFT)
> > > +#define PWM_CLKDIV_MAX                 (0x000003ff)
> > > +
> > > +#define DISP_PWM_CON_1_OFF             (0x14)
> > > +#define PWM_PERIOD_SHIFT               (0x0)
> > > +#define PWM_PERIOD_MASK                        (0xfff << PWM_PERIOD_SHIFT)
> > > +#define PWM_PERIOD_MAX                 (0x00000fff)
> > > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
> > > +#define PWM_PERIOD_BIT_SHIFT           12
> > > +
> > > +#define PWM_HIGH_WIDTH_SHIFT           (0x10)
> > > +#define PWM_HIGH_WIDTH_MASK            (0x1fff << PWM_HIGH_WIDTH_SHIFT)
> > > +
> > > +#define NUM_PWM 1
> > > +
> > > +struct mtk_disp_pwm_chip {
> > > +       struct pwm_chip chip;
> > > +       struct device   *dev;
> > > +       struct clk      *clk_main;
> > > +       struct clk      *clk_mm;
> > > +       void __iomem    *mmio_base;
> > > +};
> > > +
> > > +static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
> > > +{
> > > +       u32 val;
> > > +
> > > +       val = readl(address);
> > > +       val &= ~mask;
> > > +       val |= value;
> > > +       writel(val, address);
> > > +}
> > > +
> > > +static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > > +                              int duty_ns, int period_ns)
> > > +{
> > > +       struct mtk_disp_pwm_chip *mpc;
> > > +       u64 div, rate;
> > > +       u32 clk_div, period, high_width, rem;
> > > +
> > > +       /*
> > > +        * Find period, high_width and clk_div to suit duty_ns and period_ns.
> > > +        * Calculate proper div value to keep period value in the bound.
> > > +        *
> > > +        * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
> > > +        * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
> > > +        *
> > > +        * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
> > > +        * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
> > > +        */
> > > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > > +       rate = clk_get_rate(mpc->clk_main);
> > > +       clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
> > > +                               PWM_PERIOD_BIT_SHIFT;
> > > +       if (clk_div > PWM_CLKDIV_MAX)
> > > +               return -EINVAL;
> > > +
> > > +       div = clk_div + 1;
> > > +       period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
> > > +       if (period > 0)
> > > +               period--;
> > > +       high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
> > > +       if (high_width > 0)
> > > +               high_width--;
> > > +
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
> > > +                            clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
> > > +                            (period << PWM_PERIOD_SHIFT) |
> > > +                       (high_width << PWM_HIGH_WIDTH_SHIFT),
> > > +                       PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
> > > +
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > > +                            1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
> > > +                            0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
> > > +
> > > +       return 0;
> > > +}
> > > +
> > > +static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > > +{
> > > +       struct mtk_disp_pwm_chip *mpc;
> > > +
> > > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > > +                            1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > > +
> > > +       return 0;
> > > +}
> > > +
> > > +static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > > +{
> > > +       struct mtk_disp_pwm_chip *mpc;
> > > +
> > > +       mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
> > > +       mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
> > > +                            0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
> > > +}
> > > +
> > > +static const struct pwm_ops mtk_disp_pwm_ops = {
> > > +       .config = mtk_disp_pwm_config,
> > > +       .enable = mtk_disp_pwm_enable,
> > > +       .disable = mtk_disp_pwm_disable,
> > > +       .owner = THIS_MODULE,
> > > +};
> > > +
> > > +static int mtk_disp_pwm_probe(struct platform_device *pdev)
> > > +{
> > > +       struct mtk_disp_pwm_chip *pwm;
> > > +       struct resource *r;
> > > +       int ret;
> > > +
> > > +       pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
> > > +       if (!pwm)
> > > +               return -ENOMEM;
> > > +
> > > +       pwm->dev = &pdev->dev;
> > > +
> > > +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > +       pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> > > +       if (IS_ERR(pwm->mmio_base))
> > > +               return PTR_ERR(pwm->mmio_base);
> > > +
> > > +       pwm->clk_main = devm_clk_get(&pdev->dev, "main");
> > > +       if (IS_ERR(pwm->clk_main))
> > > +               return PTR_ERR(pwm->clk_main);
> > > +       pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
> > > +       if (IS_ERR(pwm->clk_mm))
> > > +               return PTR_ERR(pwm->clk_mm);
> > > +
> > > +       ret = clk_prepare_enable(pwm->clk_main);
> > > +       if (ret < 0)
> > > +               return ret;
> > > +       ret = clk_prepare_enable(pwm->clk_mm);
> > > +       if (ret < 0) {
> > > +               clk_disable_unprepare(pwm->clk_main);
> > > +               return ret;
> > > +       }
> > > +
> > > +       platform_set_drvdata(pdev, pwm);
> > > +
> > > +       pwm->chip.dev = &pdev->dev;
> > > +       pwm->chip.ops = &mtk_disp_pwm_ops;
> > > +       pwm->chip.base = -1;
> > > +       pwm->chip.npwm = NUM_PWM;
> > > +
> > > +       ret = pwmchip_add(&pwm->chip);
> > > +       if (ret < 0) {
> > > +               dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
> > > +               return ret;
> > > +       }
> > > +
> > > +       return 0;
> > > +}
> > > +
> > > +static int mtk_disp_pwm_remove(struct platform_device *pdev)
> > > +{
> > > +       struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
> > > +
> > > +       if (WARN_ON(!pc))
> > > +               return -ENODEV;
> > > +
> > > +       clk_disable_unprepare(pc->clk_main);
> > > +       clk_disable_unprepare(pc->clk_mm);
> > > +
> > > +       return pwmchip_remove(&pc->chip);
> > > +}
> > > +
> > > +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> > > +       { .compatible = "mediatek,mt6595-disp-pwm" },
> > 
> > Does this driver support the PWM in mt8173?
> > If so, don't you need this, too:
> > 
> >   { .compatible = "mediatek,mt8173-disp-pwm" },
> 
> Yes, it supports mt8173.
> I will add it.

If both yre compatible you don't need to add it since you have a
"mediatek,mt6595-disp-pwm" in the mt8173 device tree.

Sascha
Yingjoe Chen May 26, 2015, 8:29 a.m. UTC | #14
On Tue, 2015-05-26 at 08:05 +0200, Sascha Hauer wrote:
> On Thu, May 21, 2015 at 04:22:31PM +0800, YH Huang wrote:
> > On Mon, 2015-05-18 at 11:42 +0800, Daniel Kurtz wrote:
<...>
> > > On Mon, May 11, 2015 at 5:26 PM, YH Huang <yh.huang@mediatek.com> wrote:
> > > > +
> > > > +static const struct of_device_id mtk_disp_pwm_of_match[] = {
> > > > +       { .compatible = "mediatek,mt6595-disp-pwm" },
> > > 
> > > Does this driver support the PWM in mt8173?
> > > If so, don't you need this, too:
> > > 
> > >   { .compatible = "mediatek,mt8173-disp-pwm" },
> > 
> > Yes, it supports mt8173.
> > I will add it.
> 
> If both yre compatible you don't need to add it since you have a
> "mediatek,mt6595-disp-pwm" in the mt8173 device tree.

Hi Sascha,

We got a similar discussion about this with Mark Brown for spi driver,
please see:

http://lists.infradead.org/pipermail/linux-mediatek/2015-May/000673.html

Joe.C
diff mbox

Patch

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b1541f4..9edbb5a 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -111,6 +111,15 @@  config PWM_CLPS711X
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-clps711x.
 
+config PWM_DISP_MEDIATEK
+	tristate "MEDIATEK display PWM driver"
+	depends on OF
+	help
+	  Generic PWM framework driver for mediatek disp-pwm device.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-disp-mediatek.
+
 config PWM_EP93XX
 	tristate "Cirrus Logic EP93xx PWM support"
 	depends on ARCH_EP93XX
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index ec50eb5..c5ff72a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -8,6 +8,7 @@  obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
 obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
+obj-$(CONFIG_PWM_DISP_MEDIATEK)	+= pwm-disp-mediatek.o
 obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
 obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
 obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
diff --git a/drivers/pwm/pwm-disp-mediatek.c b/drivers/pwm/pwm-disp-mediatek.c
new file mode 100644
index 0000000..38293af
--- /dev/null
+++ b/drivers/pwm/pwm-disp-mediatek.c
@@ -0,0 +1,225 @@ 
+/*
+ * Mediatek display pulse-width-modulation controller driver.
+ * Copyright (c) 2015 MediaTek Inc.
+ * Author: YH Huang <yh.huang@mediatek.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define DISP_PWM_EN_OFF			(0x0)
+#define PWM_ENABLE_SHIFT		(0x0)
+#define PWM_ENABLE_MASK			(0x1 << PWM_ENABLE_SHIFT)
+
+#define DISP_PWM_COMMIT_OFF		(0x08)
+#define PWM_COMMIT_SHIFT		(0x0)
+#define PWM_COMMIT_MASK			(0x1 << PWM_COMMIT_SHIFT)
+
+#define DISP_PWM_CON_0_OFF		(0x10)
+#define PWM_CLKDIV_SHIFT		(0x10)
+#define PWM_CLKDIV_MASK			(0x3ff << PWM_CLKDIV_SHIFT)
+#define PWM_CLKDIV_MAX			(0x000003ff)
+
+#define DISP_PWM_CON_1_OFF		(0x14)
+#define PWM_PERIOD_SHIFT		(0x0)
+#define PWM_PERIOD_MASK			(0xfff << PWM_PERIOD_SHIFT)
+#define PWM_PERIOD_MAX			(0x00000fff)
+/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */
+#define PWM_PERIOD_BIT_SHIFT		12
+
+#define PWM_HIGH_WIDTH_SHIFT		(0x10)
+#define PWM_HIGH_WIDTH_MASK		(0x1fff << PWM_HIGH_WIDTH_SHIFT)
+
+#define NUM_PWM 1
+
+struct mtk_disp_pwm_chip {
+	struct pwm_chip	chip;
+	struct device	*dev;
+	struct clk	*clk_main;
+	struct clk	*clk_mm;
+	void __iomem	*mmio_base;
+};
+
+static void mtk_disp_pwm_setting(void __iomem *address, u32 value, u32 mask)
+{
+	u32 val;
+
+	val = readl(address);
+	val &= ~mask;
+	val |= value;
+	writel(val, address);
+}
+
+static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			       int duty_ns, int period_ns)
+{
+	struct mtk_disp_pwm_chip *mpc;
+	u64 div, rate;
+	u32 clk_div, period, high_width, rem;
+
+	/*
+	 * Find period, high_width and clk_div to suit duty_ns and period_ns.
+	 * Calculate proper div value to keep period value in the bound.
+	 *
+	 * period_ns = 10^9 * (clk_div + 1) * (period +1) / PWM_CLK_RATE
+	 * duty_ns = 10^9 * (clk_div + 1) * (high_width + 1) / PWM_CLK_RATE
+	 *
+	 * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
+	 * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1)) - 1
+	 */
+	mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
+	rate = clk_get_rate(mpc->clk_main);
+	clk_div = div_u64_rem(rate * period_ns, NSEC_PER_SEC, &rem) >>
+				PWM_PERIOD_BIT_SHIFT;
+	if (clk_div > PWM_CLKDIV_MAX)
+		return -EINVAL;
+
+	div = clk_div + 1;
+	period = div64_u64(rate * period_ns, NSEC_PER_SEC * div);
+	if (period > 0)
+		period--;
+	high_width = div64_u64(rate * duty_ns, NSEC_PER_SEC * div);
+	if (high_width > 0)
+		high_width--;
+
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_0_OFF,
+			     clk_div << PWM_CLKDIV_SHIFT, PWM_CLKDIV_MASK);
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_CON_1_OFF,
+			     (period << PWM_PERIOD_SHIFT) |
+			(high_width << PWM_HIGH_WIDTH_SHIFT),
+			PWM_PERIOD_MASK | PWM_HIGH_WIDTH_MASK);
+
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
+			     1 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_COMMIT_OFF,
+			     0 << PWM_COMMIT_SHIFT, PWM_COMMIT_MASK);
+
+	return 0;
+}
+
+static int mtk_disp_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mtk_disp_pwm_chip *mpc;
+
+	mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
+			     1 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
+
+	return 0;
+}
+
+static void mtk_disp_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mtk_disp_pwm_chip *mpc;
+
+	mpc = container_of(chip, struct mtk_disp_pwm_chip, chip);
+	mtk_disp_pwm_setting(mpc->mmio_base + DISP_PWM_EN_OFF,
+			     0 << PWM_ENABLE_SHIFT, PWM_ENABLE_MASK);
+}
+
+static const struct pwm_ops mtk_disp_pwm_ops = {
+	.config = mtk_disp_pwm_config,
+	.enable = mtk_disp_pwm_enable,
+	.disable = mtk_disp_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int mtk_disp_pwm_probe(struct platform_device *pdev)
+{
+	struct mtk_disp_pwm_chip *pwm;
+	struct resource *r;
+	int ret;
+
+	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm)
+		return -ENOMEM;
+
+	pwm->dev = &pdev->dev;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(pwm->mmio_base))
+		return PTR_ERR(pwm->mmio_base);
+
+	pwm->clk_main = devm_clk_get(&pdev->dev, "main");
+	if (IS_ERR(pwm->clk_main))
+		return PTR_ERR(pwm->clk_main);
+	pwm->clk_mm = devm_clk_get(&pdev->dev, "mm");
+	if (IS_ERR(pwm->clk_mm))
+		return PTR_ERR(pwm->clk_mm);
+
+	ret = clk_prepare_enable(pwm->clk_main);
+	if (ret < 0)
+		return ret;
+	ret = clk_prepare_enable(pwm->clk_mm);
+	if (ret < 0) {
+		clk_disable_unprepare(pwm->clk_main);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pwm);
+
+	pwm->chip.dev = &pdev->dev;
+	pwm->chip.ops = &mtk_disp_pwm_ops;
+	pwm->chip.base = -1;
+	pwm->chip.npwm = NUM_PWM;
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mtk_disp_pwm_remove(struct platform_device *pdev)
+{
+	struct mtk_disp_pwm_chip *pc = platform_get_drvdata(pdev);
+
+	if (WARN_ON(!pc))
+		return -ENODEV;
+
+	clk_disable_unprepare(pc->clk_main);
+	clk_disable_unprepare(pc->clk_mm);
+
+	return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id mtk_disp_pwm_of_match[] = {
+	{ .compatible = "mediatek,mt6595-disp-pwm" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, mtk_disp_pwm_of_match);
+
+static struct platform_driver mtk_disp_pwm_driver = {
+	.driver = {
+		.name = "mediatek-disp-pwm",
+		.owner = THIS_MODULE,
+		.of_match_table = mtk_disp_pwm_of_match,
+	},
+	.probe = mtk_disp_pwm_probe,
+	.remove = mtk_disp_pwm_remove,
+};
+
+module_platform_driver(mtk_disp_pwm_driver);
+
+MODULE_AUTHOR("YH Huang <yh.huang@mediatek.com>");
+MODULE_DESCRIPTION("MediaTek SoC display PWM driver");
+MODULE_LICENSE("GPL v2");