[v9,2/2] clk: ls1028a: Add clock driver for Display output interface
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Message ID 20191119080747.35250-2-wen.he_1@nxp.com
State Changes Requested, archived
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Series
  • [v9,1/2] dt/bindings: clk: Add YAML schemas for LS1028A Display Clock bindings
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Commit Message

Wen He Nov. 19, 2019, 8:07 a.m. UTC
Add clock driver for QorIQ LS1028A Display output interfaces(LCD, DPHY),
as implemented in TSMC CLN28HPM PLL, this PLL supports the programmable
integer division and range of the display output pixel clock's 27-594MHz.

Signed-off-by: Wen He <wen.he_1@nxp.com>
---
change in v9:
	- Use the fixed mfd in plldig_set_rate 

 drivers/clk/Kconfig      |  10 ++
 drivers/clk/Makefile     |   1 +
 drivers/clk/clk-plldig.c | 297 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 308 insertions(+)
 create mode 100644 drivers/clk/clk-plldig.c

Comments

Michael Walle Nov. 20, 2019, 2:36 p.m. UTC | #1
Hi,

> Add clock driver for QorIQ LS1028A Display output interfaces(LCD, 
> DPHY),
> as implemented in TSMC CLN28HPM PLL, this PLL supports the programmable
> integer division and range of the display output pixel clock's 
> 27-594MHz.
> 
> Signed-off-by: Wen He <wen.he_1@nxp.com>
> ---
> change in v9:
> 	- Use the fixed mfd in plldig_set_rate
> 
>  drivers/clk/Kconfig      |  10 ++
>  drivers/clk/Makefile     |   1 +
>  drivers/clk/clk-plldig.c | 297 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 308 insertions(+)
>  create mode 100644 drivers/clk/clk-plldig.c
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 0530bebfc25a..9f6b0196c604 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -218,6 +218,16 @@ config CLK_QORIQ
>  	  This adds the clock driver support for Freescale QorIQ platforms
>  	  using common clock framework.
> 
> +config CLK_LS1028A_PLLDIG
> +        tristate "Clock driver for LS1028A Display output"
> +        depends on ARCH_LAYERSCAPE || COMPILE_TEST
> +        default ARCH_LAYERSCAPE
> +        help
> +          This driver support the Display output interfaces(LCD, DPHY) 
> pixel clocks
> +          of the QorIQ Layerscape LS1028A, as implemented TSMC 
> CLN28HPM PLL. Not all
> +          features of the PLL are currently supported by the driver. 
> By default,
> +          configured bypass mode with this PLL.
> +
>  config COMMON_CLK_XGENE
>  	bool "Clock driver for APM XGene SoC"
>  	default ARCH_XGENE
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 0138fb14e6f8..97d1e5bc6de5 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -43,6 +43,7 @@ obj-$(CONFIG_ARCH_NPCM7XX)	    	+= clk-npcm7xx.o
>  obj-$(CONFIG_ARCH_NSPIRE)		+= clk-nspire.o
>  obj-$(CONFIG_COMMON_CLK_OXNAS)		+= clk-oxnas.o
>  obj-$(CONFIG_COMMON_CLK_PALMAS)		+= clk-palmas.o
> +obj-$(CONFIG_CLK_LS1028A_PLLDIG)	+= clk-plldig.o
>  obj-$(CONFIG_COMMON_CLK_PWM)		+= clk-pwm.o
>  obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
>  obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
> diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c
> new file mode 100644
> index 000000000000..f940a9d3d011
> --- /dev/null
> +++ b/drivers/clk/clk-plldig.c
> @@ -0,0 +1,297 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2019 NXP
> + *
> + * Clock driver for LS1028A Display output interfaces(LCD, DPHY).
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/bitfield.h>
> +
> +/* PLLDIG register offsets and bit masks */
> +#define PLLDIG_REG_PLLSR            0x24
> +#define PLLDIG_REG_PLLDV            0x28
> +#define PLLDIG_REG_PLLFM            0x2c
> +#define PLLDIG_REG_PLLFD            0x30
> +#define PLLDIG_REG_PLLCAL1          0x38
> +#define PLLDIG_REG_PLLCAL2          0x3c
> +#define PLLDIG_LOCK_MASK            BIT(2)
> +#define PLLDIG_REG_FIELD_SSCGBYP    BIT(30)
> +#define PLLDIG_REG_FIELD_FDEN       BIT(30)
> +#define PLLDIG_REG_FIELD_DTHDIS     GENMASK(17, 16)
> +#define PLLDIG_REG_FIELD_MULT       GENMASK(7, 0)
> +#define PLLDIG_REG_FIELD_RFDPHI1    GENMASK(30, 25)
> +
> +/* Minimum output clock frequency, in Hz */
> +#define PHI1_MIN_FREQ 27000000
> +
> +/* Maximum output clock frequency, in Hz */
> +#define PHI1_MAX_FREQ 600000000
> +
> +/* Maximum of the divider */
> +#define MAX_RFDPHI1          63
> +
> +/*
> + * Clock configuration relationship between the PHI1 
> frequency(fpll_phi) and
> + * the output frequency of the PLL is determined by the PLLDV, 
> according to
> + * the following equation:
> + * fpll_phi = (pll_ref * mfd) / div_rfdphi1
> + */
> +struct plldig_phi1_param {
> +	unsigned long rate;
> +	unsigned int rfdphi1;
> +	unsigned int mfd;
> +};
> +
> +static const struct clk_parent_data parent_data[] = {
> +	{.index = 0},
> +};
> +
> +struct clk_plldig {
> +	struct clk_hw hw;
> +	void __iomem *regs;
> +	unsigned int mfd;
> +};
> +
> +#define to_clk_plldig(_hw)	container_of(_hw, struct clk_plldig, hw)
> +
> +static int plldig_enable(struct clk_hw *hw)
> +{
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +	u32 val;
> +
> +	val = readl(data->regs + PLLDIG_REG_PLLFM);
> +	/*
> +	 * Use Bypass mode with PLL off by default, the frequency overshoot
> +	 * detector output was disable. SSCG Bypass mode should be enable.
> +	 */
> +	val |= PLLDIG_REG_FIELD_SSCGBYP;
> +	writel(val, data->regs + PLLDIG_REG_PLLFM);
> +
> +	val = readl(data->regs + PLLDIG_REG_PLLFD);
> +	/* Disable dither and Sigma delta modulation in bypass mode */
> +	val |= FIELD_PREP(PLLDIG_REG_FIELD_FDEN, 0x1) |

Unlike mentioned in the documentation, FDEN is "fractional divider 
enable".



> +	       FIELD_PREP(PLLDIG_REG_FIELD_DTHDIS, 0x3);
> +
> +	writel(val, data->regs + PLLDIG_REG_PLLFD);
> +
> +	return 0;
> +}
> +
> +static void plldig_disable(struct clk_hw *hw)
> +{
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +	u32 val;
> +
> +	val = readl(data->regs + PLLDIG_REG_PLLFM);
> +
> +	val &= ~PLLDIG_REG_FIELD_SSCGBYP;
> +	val |= FIELD_PREP(PLLDIG_REG_FIELD_SSCGBYP, 0x0);
> +
> +	writel(val, data->regs + PLLDIG_REG_PLLFM);
> +}
> +
> +static int plldig_is_enabled(struct clk_hw *hw)
> +{
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +
> +	return (readl(data->regs + PLLDIG_REG_PLLFM) &
> +			      PLLDIG_REG_FIELD_SSCGBYP);
> +}
> +
> +static unsigned long plldig_recalc_rate(struct clk_hw *hw,
> +		unsigned long parent_rate)
> +{
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +	u32 mult, div, val;
> +
> +	val = readl(data->regs + PLLDIG_REG_PLLDV);
> +
> +	/* Check if PLL is bypassed */
> +	if (val & PLLDIG_REG_FIELD_SSCGBYP)
> +		return parent_rate;
> +
> +	/* Checkout multiplication factor divider value */
> +	mult = FIELD_GET(PLLDIG_REG_FIELD_MULT, val);
> +
> +	/* Checkout divider value of the output frequency */
> +	div = FIELD_GET(PLLDIG_REG_FIELD_RFDPHI1, val);
> +
> +	return (parent_rate * mult) / div;
> +}
> +
> +static int plldig_calc_target_rate(unsigned long target_rate,
> +				   unsigned long parent_rate,
> +				   struct plldig_phi1_param *phi1)
> +{
> +	unsigned int div, ret;
> +	unsigned long round_rate;
> +
> +	/* Range limitation of the request target rate */
> +	if (target_rate > PHI1_MAX_FREQ)
> +		target_rate = PHI1_MAX_FREQ;
> +	else if (target_rate < PHI1_MIN_FREQ)
> +		target_rate = PHI1_MIN_FREQ;
> +
> +	/*
> +	 * Firstly, check the request target rate whether is divisible
> +	 * by the best VCO frequency.
> +	 */
> +	round_rate = parent_rate * phi1->mfd;
> +	div = round_rate / target_rate;
Can't you use DIV_ROUND_UP(), DIV_ROUND_DOWN_ULL() or 
DIV_ROUND_CLOSEST_ULL() and drop the stuff below except the range check?


> +	if (!div || div > MAX_RFDPHI1)
> +		return -EINVAL;
> +
> +	ret = round_rate % target_rate;
> +	if (ret) {
> +		/*
> +		 * Rounded down the request target rate, VESA specifies
> +		 * 0.5% pixel clock tolerance, therefore this algorithm
> +		 * can able to compatible a lot of request rates within
> +		 * range of the tolerance.
> +		 */
> +		round_rate += (target_rate / 2);
> +		div = round_rate / target_rate;
> +		if (!div || div > MAX_RFDPHI1)
> +			return -EINVAL;
> +	}
> +
> +	phi1->rfdphi1 = div;
> +	phi1->rate = target_rate;
> +
> +	return 0;
> +}
> +
> +static int plldig_determine_rate(struct clk_hw *hw,
> +				 struct clk_rate_request *req)
> +{
> +	int ret;
> +	unsigned long parent_rate;
> +	struct clk_hw *parent;
> +	struct plldig_phi1_param phi1_param;
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +
> +	if (!req->rate)
> +		return -ERANGE;
> +
> +	phi1_param.mfd = data->mfd;
> +	parent = clk_hw_get_parent(hw);
> +	parent_rate = clk_hw_get_rate(parent);
> +
> +	ret = plldig_calc_target_rate(req->rate, parent_rate, &phi1_param);
> +	if (ret)
> +		return ret;
> +
> +	req->rate = phi1_param.rate;
> +
> +	return 0;
> +}
> +
> +static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
> +		unsigned long parent_rate)
> +{
> +	struct clk_plldig *data = to_clk_plldig(hw);
> +	struct plldig_phi1_param phi1_param;
> +	unsigned int val, cond;
> +	int ret;
> +
> +	phi1_param.mfd = data->mfd;
> +	ret = plldig_calc_target_rate(rate, parent_rate, &phi1_param);
> +	if (ret)
> +		return ret;
> +
> +	val = readl(data->regs + PLLDIG_REG_PLLDV);
> +	val = FIELD_PREP(PLLDIG_REG_FIELD_MULT, phi1_param.mfd) |
> +	      FIELD_PREP(PLLDIG_REG_FIELD_RFDPHI1, phi1_param.rfdphi1);
> +
> +	writel(val, data->regs + PLLDIG_REG_PLLDV);
> +
> +	/* delay 200us make sure that old lock state is cleared */
> +	udelay(200);
> +
> +	/* Wait until PLL is locked or timeout (maximum 1000 usecs) */
> +	return readl_poll_timeout_atomic(data->regs + PLLDIG_REG_PLLSR, cond,
> +					 cond & PLLDIG_LOCK_MASK, 0,
> +					 USEC_PER_MSEC);
> +}
> +
> +static const struct clk_ops plldig_clk_ops = {
> +	.enable = plldig_enable,
> +	.disable = plldig_disable,
> +	.is_enabled = plldig_is_enabled,
> +	.recalc_rate = plldig_recalc_rate,
> +	.determine_rate = plldig_determine_rate,
> +	.set_rate = plldig_set_rate,
> +};
> +
> +static int plldig_clk_probe(struct platform_device *pdev)
> +{
> +	struct clk_plldig *data;
> +	struct resource *mem;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	data->regs = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(data->regs))
> +		return PTR_ERR(data->regs);
> +
> +	 /*
> +	  * Support to get the best loop multiplication divider value
> +	  * from DTS file, since this PLL can't changed this value on
> +	  * the fly, write the fixed value.
> +	  */
> +	ret = of_property_read_u32(dev->of_node, "best-mfd", &data->mfd);
> +	if (ret)
> +		data->mfd = 0x2c;

IMHO this is a really bad device tree binding. First it is not described 
anywhere, ie it is missing in the dt-bindings file and second, to 
actually make use of the "best-mfd" the user has to know the parent 
clock, the desired vco frequency and have to calculate it by himself. 
IMHO a better one would be something like "vco-frequency". Also you 
should use the fractional divider to get better results. Using the 
fractional divider almost any VCO frequency is possible (within a 
certain range which should be checked [650 MHz to 1300 MHz]).


> +
> +	writel(data->mfd, data->regs + PLLDIG_REG_PLLDV);
> +
> +	data->hw.init = CLK_HW_INIT_PARENTS_DATA("dpclk",
> +						 parent_data,
> +						 &plldig_clk_ops,
> +						 0);
> +
> +	ret = devm_clk_hw_register(dev, &data->hw);
> +	if (ret) {
> +		dev_err(dev, "failed to register %s clock\n",
> +						dev->of_node->name);
> +		return ret;
> +	}
> +
> +	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> +					   &data->hw);
> +}
> +
> +static const struct of_device_id plldig_clk_id[] = {
> +	{ .compatible = "fsl,ls1028a-plldig"},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, plldig_clk_id);
> +
> +static struct platform_driver plldig_clk_driver = {
> +	.driver = {
> +		.name = "plldig-clock",
> +		.of_match_table = plldig_clk_id,
> +	},
> +	.probe = plldig_clk_probe,
> +};
> +module_platform_driver(plldig_clk_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Wen He <wen.he_1@nxp.com>");
> +MODULE_DESCRIPTION("LS1028A Display output interface pixel clock 
> driver");

-michael
Wen He Nov. 21, 2019, 4:04 p.m. UTC | #2
> -----Original Message-----
> From: Michael Walle <michael@walle.cc>
> Sent: 2019年11月20日 22:36
> To: Wen He <wen.he_1@nxp.com>
> Cc: devicetree@vger.kernel.org; Leo Li <leoyang.li@nxp.com>;
> linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org;
> mark.rutland@arm.com; mturquette@baylibre.com; robh+dt@kernel.org;
> sboyd@kernel.org
> Subject: [EXT] Re: [v9 2/2] clk: ls1028a: Add clock driver for Display output
> interface
> 
> 
> Hi,

Hi Michael,

> 
> > Add clock driver for QorIQ LS1028A Display output interfaces(LCD,
> > DPHY), as implemented in TSMC CLN28HPM PLL, this PLL supports the
> > programmable integer division and range of the display output pixel
> > clock's 27-594MHz.
> >
> > Signed-off-by: Wen He <wen.he_1@nxp.com>
> > ---
> > change in v9:
> >       - Use the fixed mfd in plldig_set_rate
> >
> >  drivers/clk/Kconfig      |  10 ++
> >  drivers/clk/Makefile     |   1 +
> >  drivers/clk/clk-plldig.c | 297
> > +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 308 insertions(+)
> >  create mode 100644 drivers/clk/clk-plldig.c
> >
> > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index
> > 0530bebfc25a..9f6b0196c604 100644
> > --- a/drivers/clk/Kconfig
> > +++ b/drivers/clk/Kconfig
> > @@ -218,6 +218,16 @@ config CLK_QORIQ
> >         This adds the clock driver support for Freescale QorIQ platforms
> >         using common clock framework.
> >
> > +config CLK_LS1028A_PLLDIG
> > +        tristate "Clock driver for LS1028A Display output"
> > +        depends on ARCH_LAYERSCAPE || COMPILE_TEST
> > +        default ARCH_LAYERSCAPE
> > +        help
> > +          This driver support the Display output interfaces(LCD,
> > +DPHY)
> > pixel clocks
> > +          of the QorIQ Layerscape LS1028A, as implemented TSMC
> > CLN28HPM PLL. Not all
> > +          features of the PLL are currently supported by the driver.
> > By default,
> > +          configured bypass mode with this PLL.
> > +
> >  config COMMON_CLK_XGENE
> >       bool "Clock driver for APM XGene SoC"
> >       default ARCH_XGENE
> > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index
> > 0138fb14e6f8..97d1e5bc6de5 100644
> > --- a/drivers/clk/Makefile
> > +++ b/drivers/clk/Makefile
> > @@ -43,6 +43,7 @@ obj-$(CONFIG_ARCH_NPCM7XX)          +=
> clk-npcm7xx.o
> >  obj-$(CONFIG_ARCH_NSPIRE)            += clk-nspire.o
> >  obj-$(CONFIG_COMMON_CLK_OXNAS)               += clk-oxnas.o
> >  obj-$(CONFIG_COMMON_CLK_PALMAS)              += clk-palmas.o
> > +obj-$(CONFIG_CLK_LS1028A_PLLDIG)     += clk-plldig.o
> >  obj-$(CONFIG_COMMON_CLK_PWM)         += clk-pwm.o
> >  obj-$(CONFIG_CLK_QORIQ)                      += clk-qoriq.o
> >  obj-$(CONFIG_COMMON_CLK_RK808)               += clk-rk808.o
> > diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c new
> > file mode 100644 index 000000000000..f940a9d3d011
> > --- /dev/null
> > +++ b/drivers/clk/clk-plldig.c
> > @@ -0,0 +1,297 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright 2019 NXP
> > + *
> > + * Clock driver for LS1028A Display output interfaces(LCD, DPHY).
> > + */
> > +
> > +#include <linux/clk-provider.h>
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/of.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +#include <linux/bitfield.h>
> > +
> > +/* PLLDIG register offsets and bit masks */
> > +#define PLLDIG_REG_PLLSR            0x24
> > +#define PLLDIG_REG_PLLDV            0x28
> > +#define PLLDIG_REG_PLLFM            0x2c
> > +#define PLLDIG_REG_PLLFD            0x30
> > +#define PLLDIG_REG_PLLCAL1          0x38
> > +#define PLLDIG_REG_PLLCAL2          0x3c
> > +#define PLLDIG_LOCK_MASK            BIT(2)
> > +#define PLLDIG_REG_FIELD_SSCGBYP    BIT(30)
> > +#define PLLDIG_REG_FIELD_FDEN       BIT(30)
> > +#define PLLDIG_REG_FIELD_DTHDIS     GENMASK(17, 16)
> > +#define PLLDIG_REG_FIELD_MULT       GENMASK(7, 0)
> > +#define PLLDIG_REG_FIELD_RFDPHI1    GENMASK(30, 25)
> > +
> > +/* Minimum output clock frequency, in Hz */ #define PHI1_MIN_FREQ
> > +27000000
> > +
> > +/* Maximum output clock frequency, in Hz */ #define PHI1_MAX_FREQ
> > +600000000
> > +
> > +/* Maximum of the divider */
> > +#define MAX_RFDPHI1          63
> > +
> > +/*
> > + * Clock configuration relationship between the PHI1
> > frequency(fpll_phi) and
> > + * the output frequency of the PLL is determined by the PLLDV,
> > according to
> > + * the following equation:
> > + * fpll_phi = (pll_ref * mfd) / div_rfdphi1  */ struct
> > +plldig_phi1_param {
> > +     unsigned long rate;
> > +     unsigned int rfdphi1;
> > +     unsigned int mfd;
> > +};
> > +
> > +static const struct clk_parent_data parent_data[] = {
> > +     {.index = 0},
> > +};
> > +
> > +struct clk_plldig {
> > +     struct clk_hw hw;
> > +     void __iomem *regs;
> > +     unsigned int mfd;
> > +};
> > +
> > +#define to_clk_plldig(_hw)   container_of(_hw, struct clk_plldig, hw)
> > +
> > +static int plldig_enable(struct clk_hw *hw) {
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +     u32 val;
> > +
> > +     val = readl(data->regs + PLLDIG_REG_PLLFM);
> > +     /*
> > +      * Use Bypass mode with PLL off by default, the frequency overshoot
> > +      * detector output was disable. SSCG Bypass mode should be enable.
> > +      */
> > +     val |= PLLDIG_REG_FIELD_SSCGBYP;
> > +     writel(val, data->regs + PLLDIG_REG_PLLFM);
> > +
> > +     val = readl(data->regs + PLLDIG_REG_PLLFD);
> > +     /* Disable dither and Sigma delta modulation in bypass mode */
> > +     val |= FIELD_PREP(PLLDIG_REG_FIELD_FDEN, 0x1) |
> 
> Unlike mentioned in the documentation, FDEN is "fractional divider enable".
> 
> 

Yes, this point just confirmed in yesterday.

> 
> > +            FIELD_PREP(PLLDIG_REG_FIELD_DTHDIS, 0x3);
> > +
> > +     writel(val, data->regs + PLLDIG_REG_PLLFD);
> > +
> > +     return 0;
> > +}
> > +
> > +static void plldig_disable(struct clk_hw *hw) {
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +     u32 val;
> > +
> > +     val = readl(data->regs + PLLDIG_REG_PLLFM);
> > +
> > +     val &= ~PLLDIG_REG_FIELD_SSCGBYP;
> > +     val |= FIELD_PREP(PLLDIG_REG_FIELD_SSCGBYP, 0x0);
> > +
> > +     writel(val, data->regs + PLLDIG_REG_PLLFM); }
> > +
> > +static int plldig_is_enabled(struct clk_hw *hw) {
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +
> > +     return (readl(data->regs + PLLDIG_REG_PLLFM) &
> > +                           PLLDIG_REG_FIELD_SSCGBYP); }
> > +
> > +static unsigned long plldig_recalc_rate(struct clk_hw *hw,
> > +             unsigned long parent_rate) {
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +     u32 mult, div, val;
> > +
> > +     val = readl(data->regs + PLLDIG_REG_PLLDV);
> > +
> > +     /* Check if PLL is bypassed */
> > +     if (val & PLLDIG_REG_FIELD_SSCGBYP)
> > +             return parent_rate;
> > +
> > +     /* Checkout multiplication factor divider value */
> > +     mult = FIELD_GET(PLLDIG_REG_FIELD_MULT, val);
> > +
> > +     /* Checkout divider value of the output frequency */
> > +     div = FIELD_GET(PLLDIG_REG_FIELD_RFDPHI1, val);
> > +
> > +     return (parent_rate * mult) / div; }
> > +
> > +static int plldig_calc_target_rate(unsigned long target_rate,
> > +                                unsigned long parent_rate,
> > +                                struct plldig_phi1_param *phi1) {
> > +     unsigned int div, ret;
> > +     unsigned long round_rate;
> > +
> > +     /* Range limitation of the request target rate */
> > +     if (target_rate > PHI1_MAX_FREQ)
> > +             target_rate = PHI1_MAX_FREQ;
> > +     else if (target_rate < PHI1_MIN_FREQ)
> > +             target_rate = PHI1_MIN_FREQ;
> > +
> > +     /*
> > +      * Firstly, check the request target rate whether is divisible
> > +      * by the best VCO frequency.
> > +      */
> > +     round_rate = parent_rate * phi1->mfd;
> > +     div = round_rate / target_rate;
> Can't you use DIV_ROUND_UP(), DIV_ROUND_DOWN_ULL() or
> DIV_ROUND_CLOSEST_ULL() and drop the stuff below except the range check?
> 

Great advice.

> 
> > +     if (!div || div > MAX_RFDPHI1)
> > +             return -EINVAL;
> > +
> > +     ret = round_rate % target_rate;
> > +     if (ret) {
> > +             /*
> > +              * Rounded down the request target rate, VESA specifies
> > +              * 0.5% pixel clock tolerance, therefore this algorithm
> > +              * can able to compatible a lot of request rates within
> > +              * range of the tolerance.
> > +              */
> > +             round_rate += (target_rate / 2);
> > +             div = round_rate / target_rate;
> > +             if (!div || div > MAX_RFDPHI1)
> > +                     return -EINVAL;
> > +     }
> > +
> > +     phi1->rfdphi1 = div;
> > +     phi1->rate = target_rate;
> > +
> > +     return 0;
> > +}
> > +
> > +static int plldig_determine_rate(struct clk_hw *hw,
> > +                              struct clk_rate_request *req) {
> > +     int ret;
> > +     unsigned long parent_rate;
> > +     struct clk_hw *parent;
> > +     struct plldig_phi1_param phi1_param;
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +
> > +     if (!req->rate)
> > +             return -ERANGE;
> > +
> > +     phi1_param.mfd = data->mfd;
> > +     parent = clk_hw_get_parent(hw);
> > +     parent_rate = clk_hw_get_rate(parent);
> > +
> > +     ret = plldig_calc_target_rate(req->rate, parent_rate, &phi1_param);
> > +     if (ret)
> > +             return ret;
> > +
> > +     req->rate = phi1_param.rate;
> > +
> > +     return 0;
> > +}
> > +
> > +static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
> > +             unsigned long parent_rate) {
> > +     struct clk_plldig *data = to_clk_plldig(hw);
> > +     struct plldig_phi1_param phi1_param;
> > +     unsigned int val, cond;
> > +     int ret;
> > +
> > +     phi1_param.mfd = data->mfd;
> > +     ret = plldig_calc_target_rate(rate, parent_rate, &phi1_param);
> > +     if (ret)
> > +             return ret;
> > +
> > +     val = readl(data->regs + PLLDIG_REG_PLLDV);
> > +     val = FIELD_PREP(PLLDIG_REG_FIELD_MULT, phi1_param.mfd) |
> > +           FIELD_PREP(PLLDIG_REG_FIELD_RFDPHI1,
> phi1_param.rfdphi1);
> > +
> > +     writel(val, data->regs + PLLDIG_REG_PLLDV);
> > +
> > +     /* delay 200us make sure that old lock state is cleared */
> > +     udelay(200);
> > +
> > +     /* Wait until PLL is locked or timeout (maximum 1000 usecs) */
> > +     return readl_poll_timeout_atomic(data->regs + PLLDIG_REG_PLLSR,
> cond,
> > +                                      cond & PLLDIG_LOCK_MASK, 0,
> > +                                      USEC_PER_MSEC); }
> > +
> > +static const struct clk_ops plldig_clk_ops = {
> > +     .enable = plldig_enable,
> > +     .disable = plldig_disable,
> > +     .is_enabled = plldig_is_enabled,
> > +     .recalc_rate = plldig_recalc_rate,
> > +     .determine_rate = plldig_determine_rate,
> > +     .set_rate = plldig_set_rate,
> > +};
> > +
> > +static int plldig_clk_probe(struct platform_device *pdev) {
> > +     struct clk_plldig *data;
> > +     struct resource *mem;
> > +     struct device *dev = &pdev->dev;
> > +     int ret;
> > +
> > +     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +     data->regs = devm_ioremap_resource(dev, mem);
> > +     if (IS_ERR(data->regs))
> > +             return PTR_ERR(data->regs);
> > +
> > +      /*
> > +       * Support to get the best loop multiplication divider value
> > +       * from DTS file, since this PLL can't changed this value on
> > +       * the fly, write the fixed value.
> > +       */
> > +     ret = of_property_read_u32(dev->of_node, "best-mfd", &data->mfd);
> > +     if (ret)
> > +             data->mfd = 0x2c;
> 
> IMHO this is a really bad device tree binding. First it is not described anywhere,
> ie it is missing in the dt-bindings file and second, to actually make use of the
> "best-mfd" the user has to know the parent clock, the desired vco frequency
> and have to calculate it by himself.
> IMHO a better one would be something like "vco-frequency". Also you should
> use the fractional divider to get better results. Using the fractional divider
> almost any VCO frequency is possible (within a certain range which should be
> checked [650 MHz to 1300 MHz]).
> 

Yes, the fractional part can covered range is 27MHz, it can almost any VCO frequency. 
the fractional divider should be supported in this driver.

I also knew the device tree binding is bad specially way, but here just want to
provide a simple solution used to configure the MFD value for users requirement.
So you think that should be use "vco-frequency" instead of the "best-mfd" in dts used to
avoid user recalculate it(user may don’t know the parent rate)?

Best Regards,
Wen

> 
> > +
> > +     writel(data->mfd, data->regs + PLLDIG_REG_PLLDV);
> > +
> > +     data->hw.init = CLK_HW_INIT_PARENTS_DATA("dpclk",
> > +                                              parent_data,
> > +                                              &plldig_clk_ops,
> > +                                              0);
> > +
> > +     ret = devm_clk_hw_register(dev, &data->hw);
> > +     if (ret) {
> > +             dev_err(dev, "failed to register %s clock\n",
> > +                                             dev->of_node->name);
> > +             return ret;
> > +     }
> > +
> > +     return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> > +                                        &data->hw); }
> > +
> > +static const struct of_device_id plldig_clk_id[] = {
> > +     { .compatible = "fsl,ls1028a-plldig"},
> > +     { }
> > +};
> > +MODULE_DEVICE_TABLE(of, plldig_clk_id);
> > +
> > +static struct platform_driver plldig_clk_driver = {
> > +     .driver = {
> > +             .name = "plldig-clock",
> > +             .of_match_table = plldig_clk_id,
> > +     },
> > +     .probe = plldig_clk_probe,
> > +};
> > +module_platform_driver(plldig_clk_driver);
> > +
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_AUTHOR("Wen He <wen.he_1@nxp.com>");
> > +MODULE_DESCRIPTION("LS1028A Display output interface pixel clock
> > driver");
> 
> -michael
Michael Walle Nov. 22, 2019, 3:25 p.m. UTC | #3
Am 2019-11-21 17:04, schrieb Wen He:
>> -----Original Message-----
>> From: Michael Walle <michael@walle.cc>
>> Sent: 2019年11月20日 22:36
>> To: Wen He <wen.he_1@nxp.com>
>> Cc: devicetree@vger.kernel.org; Leo Li <leoyang.li@nxp.com>;
>> linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org;
>> mark.rutland@arm.com; mturquette@baylibre.com; robh+dt@kernel.org;
>> sboyd@kernel.org
>> Subject: [EXT] Re: [v9 2/2] clk: ls1028a: Add clock driver for Display 
>> output
>> interface
>> 
>> 
>> Hi,
> 
> Hi Michael,
> 
>> 
>> > Add clock driver for QorIQ LS1028A Display output interfaces(LCD,
>> > DPHY), as implemented in TSMC CLN28HPM PLL, this PLL supports the
>> > programmable integer division and range of the display output pixel
>> > clock's 27-594MHz.
>> >
>> > Signed-off-by: Wen He <wen.he_1@nxp.com>
>> > ---
>> > change in v9:
>> >       - Use the fixed mfd in plldig_set_rate
>> >
>> >  drivers/clk/Kconfig      |  10 ++
>> >  drivers/clk/Makefile     |   1 +
>> >  drivers/clk/clk-plldig.c | 297
>> > +++++++++++++++++++++++++++++++++++++++
>> >  3 files changed, 308 insertions(+)
>> >  create mode 100644 drivers/clk/clk-plldig.c
>> >
>> > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index
>> > 0530bebfc25a..9f6b0196c604 100644
>> > --- a/drivers/clk/Kconfig
>> > +++ b/drivers/clk/Kconfig
>> > @@ -218,6 +218,16 @@ config CLK_QORIQ
>> >         This adds the clock driver support for Freescale QorIQ platforms
>> >         using common clock framework.
>> >
>> > +config CLK_LS1028A_PLLDIG
>> > +        tristate "Clock driver for LS1028A Display output"
>> > +        depends on ARCH_LAYERSCAPE || COMPILE_TEST
>> > +        default ARCH_LAYERSCAPE
>> > +        help
>> > +          This driver support the Display output interfaces(LCD,
>> > +DPHY)
>> > pixel clocks
>> > +          of the QorIQ Layerscape LS1028A, as implemented TSMC
>> > CLN28HPM PLL. Not all
>> > +          features of the PLL are currently supported by the driver.
>> > By default,
>> > +          configured bypass mode with this PLL.
>> > +
>> >  config COMMON_CLK_XGENE
>> >       bool "Clock driver for APM XGene SoC"
>> >       default ARCH_XGENE
>> > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index
>> > 0138fb14e6f8..97d1e5bc6de5 100644
>> > --- a/drivers/clk/Makefile
>> > +++ b/drivers/clk/Makefile
>> > @@ -43,6 +43,7 @@ obj-$(CONFIG_ARCH_NPCM7XX)          +=
>> clk-npcm7xx.o
>> >  obj-$(CONFIG_ARCH_NSPIRE)            += clk-nspire.o
>> >  obj-$(CONFIG_COMMON_CLK_OXNAS)               += clk-oxnas.o
>> >  obj-$(CONFIG_COMMON_CLK_PALMAS)              += clk-palmas.o
>> > +obj-$(CONFIG_CLK_LS1028A_PLLDIG)     += clk-plldig.o
>> >  obj-$(CONFIG_COMMON_CLK_PWM)         += clk-pwm.o
>> >  obj-$(CONFIG_CLK_QORIQ)                      += clk-qoriq.o
>> >  obj-$(CONFIG_COMMON_CLK_RK808)               += clk-rk808.o
>> > diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c new
>> > file mode 100644 index 000000000000..f940a9d3d011
>> > --- /dev/null
>> > +++ b/drivers/clk/clk-plldig.c
>> > @@ -0,0 +1,297 @@
>> > +// SPDX-License-Identifier: GPL-2.0
>> > +/*
>> > + * Copyright 2019 NXP
>> > + *
>> > + * Clock driver for LS1028A Display output interfaces(LCD, DPHY).
>> > + */
>> > +
>> > +#include <linux/clk-provider.h>
>> > +#include <linux/device.h>
>> > +#include <linux/module.h>
>> > +#include <linux/err.h>
>> > +#include <linux/io.h>
>> > +#include <linux/iopoll.h>
>> > +#include <linux/of.h>
>> > +#include <linux/of_address.h>
>> > +#include <linux/of_device.h>
>> > +#include <linux/platform_device.h>
>> > +#include <linux/slab.h>
>> > +#include <linux/bitfield.h>
>> > +
>> > +/* PLLDIG register offsets and bit masks */
>> > +#define PLLDIG_REG_PLLSR            0x24
>> > +#define PLLDIG_REG_PLLDV            0x28
>> > +#define PLLDIG_REG_PLLFM            0x2c
>> > +#define PLLDIG_REG_PLLFD            0x30
>> > +#define PLLDIG_REG_PLLCAL1          0x38
>> > +#define PLLDIG_REG_PLLCAL2          0x3c
>> > +#define PLLDIG_LOCK_MASK            BIT(2)
>> > +#define PLLDIG_REG_FIELD_SSCGBYP    BIT(30)
>> > +#define PLLDIG_REG_FIELD_FDEN       BIT(30)
>> > +#define PLLDIG_REG_FIELD_DTHDIS     GENMASK(17, 16)
>> > +#define PLLDIG_REG_FIELD_MULT       GENMASK(7, 0)
>> > +#define PLLDIG_REG_FIELD_RFDPHI1    GENMASK(30, 25)
>> > +
>> > +/* Minimum output clock frequency, in Hz */ #define PHI1_MIN_FREQ
>> > +27000000
>> > +
>> > +/* Maximum output clock frequency, in Hz */ #define PHI1_MAX_FREQ
>> > +600000000
>> > +
>> > +/* Maximum of the divider */
>> > +#define MAX_RFDPHI1          63
>> > +
>> > +/*
>> > + * Clock configuration relationship between the PHI1
>> > frequency(fpll_phi) and
>> > + * the output frequency of the PLL is determined by the PLLDV,
>> > according to
>> > + * the following equation:
>> > + * fpll_phi = (pll_ref * mfd) / div_rfdphi1  */ struct
>> > +plldig_phi1_param {
>> > +     unsigned long rate;
>> > +     unsigned int rfdphi1;
>> > +     unsigned int mfd;
>> > +};
>> > +
>> > +static const struct clk_parent_data parent_data[] = {
>> > +     {.index = 0},
>> > +};
>> > +
>> > +struct clk_plldig {
>> > +     struct clk_hw hw;
>> > +     void __iomem *regs;
>> > +     unsigned int mfd;
>> > +};
>> > +
>> > +#define to_clk_plldig(_hw)   container_of(_hw, struct clk_plldig, hw)
>> > +
>> > +static int plldig_enable(struct clk_hw *hw) {
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +     u32 val;
>> > +
>> > +     val = readl(data->regs + PLLDIG_REG_PLLFM);
>> > +     /*
>> > +      * Use Bypass mode with PLL off by default, the frequency overshoot
>> > +      * detector output was disable. SSCG Bypass mode should be enable.
>> > +      */
>> > +     val |= PLLDIG_REG_FIELD_SSCGBYP;
>> > +     writel(val, data->regs + PLLDIG_REG_PLLFM);
>> > +
>> > +     val = readl(data->regs + PLLDIG_REG_PLLFD);
>> > +     /* Disable dither and Sigma delta modulation in bypass mode */
>> > +     val |= FIELD_PREP(PLLDIG_REG_FIELD_FDEN, 0x1) |
>> 
>> Unlike mentioned in the documentation, FDEN is "fractional divider 
>> enable".
>> 
>> 
> 
> Yes, this point just confirmed in yesterday.
> 
>> 
>> > +            FIELD_PREP(PLLDIG_REG_FIELD_DTHDIS, 0x3);
>> > +
>> > +     writel(val, data->regs + PLLDIG_REG_PLLFD);
>> > +
>> > +     return 0;
>> > +}
>> > +
>> > +static void plldig_disable(struct clk_hw *hw) {
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +     u32 val;
>> > +
>> > +     val = readl(data->regs + PLLDIG_REG_PLLFM);
>> > +
>> > +     val &= ~PLLDIG_REG_FIELD_SSCGBYP;
>> > +     val |= FIELD_PREP(PLLDIG_REG_FIELD_SSCGBYP, 0x0);
>> > +
>> > +     writel(val, data->regs + PLLDIG_REG_PLLFM); }
>> > +
>> > +static int plldig_is_enabled(struct clk_hw *hw) {
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +
>> > +     return (readl(data->regs + PLLDIG_REG_PLLFM) &
>> > +                           PLLDIG_REG_FIELD_SSCGBYP); }
>> > +
>> > +static unsigned long plldig_recalc_rate(struct clk_hw *hw,
>> > +             unsigned long parent_rate) {
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +     u32 mult, div, val;
>> > +
>> > +     val = readl(data->regs + PLLDIG_REG_PLLDV);
>> > +
>> > +     /* Check if PLL is bypassed */
>> > +     if (val & PLLDIG_REG_FIELD_SSCGBYP)
>> > +             return parent_rate;
>> > +
>> > +     /* Checkout multiplication factor divider value */
>> > +     mult = FIELD_GET(PLLDIG_REG_FIELD_MULT, val);
>> > +
>> > +     /* Checkout divider value of the output frequency */
>> > +     div = FIELD_GET(PLLDIG_REG_FIELD_RFDPHI1, val);
>> > +
>> > +     return (parent_rate * mult) / div; }
>> > +
>> > +static int plldig_calc_target_rate(unsigned long target_rate,
>> > +                                unsigned long parent_rate,
>> > +                                struct plldig_phi1_param *phi1) {
>> > +     unsigned int div, ret;
>> > +     unsigned long round_rate;
>> > +
>> > +     /* Range limitation of the request target rate */
>> > +     if (target_rate > PHI1_MAX_FREQ)
>> > +             target_rate = PHI1_MAX_FREQ;
>> > +     else if (target_rate < PHI1_MIN_FREQ)
>> > +             target_rate = PHI1_MIN_FREQ;
>> > +
>> > +     /*
>> > +      * Firstly, check the request target rate whether is divisible
>> > +      * by the best VCO frequency.
>> > +      */
>> > +     round_rate = parent_rate * phi1->mfd;
>> > +     div = round_rate / target_rate;
>> Can't you use DIV_ROUND_UP(), DIV_ROUND_DOWN_ULL() or
>> DIV_ROUND_CLOSEST_ULL() and drop the stuff below except the range 
>> check?
>> 
> 
> Great advice.
> 
>> 
>> > +     if (!div || div > MAX_RFDPHI1)
>> > +             return -EINVAL;
>> > +
>> > +     ret = round_rate % target_rate;
>> > +     if (ret) {
>> > +             /*
>> > +              * Rounded down the request target rate, VESA specifies
>> > +              * 0.5% pixel clock tolerance, therefore this algorithm
>> > +              * can able to compatible a lot of request rates within
>> > +              * range of the tolerance.
>> > +              */
>> > +             round_rate += (target_rate / 2);
>> > +             div = round_rate / target_rate;
>> > +             if (!div || div > MAX_RFDPHI1)
>> > +                     return -EINVAL;
>> > +     }
>> > +
>> > +     phi1->rfdphi1 = div;
>> > +     phi1->rate = target_rate;
>> > +
>> > +     return 0;
>> > +}
>> > +
>> > +static int plldig_determine_rate(struct clk_hw *hw,
>> > +                              struct clk_rate_request *req) {
>> > +     int ret;
>> > +     unsigned long parent_rate;
>> > +     struct clk_hw *parent;
>> > +     struct plldig_phi1_param phi1_param;
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +
>> > +     if (!req->rate)
>> > +             return -ERANGE;
>> > +
>> > +     phi1_param.mfd = data->mfd;
>> > +     parent = clk_hw_get_parent(hw);
>> > +     parent_rate = clk_hw_get_rate(parent);
>> > +
>> > +     ret = plldig_calc_target_rate(req->rate, parent_rate, &phi1_param);
>> > +     if (ret)
>> > +             return ret;
>> > +
>> > +     req->rate = phi1_param.rate;
>> > +
>> > +     return 0;
>> > +}
>> > +
>> > +static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
>> > +             unsigned long parent_rate) {
>> > +     struct clk_plldig *data = to_clk_plldig(hw);
>> > +     struct plldig_phi1_param phi1_param;
>> > +     unsigned int val, cond;
>> > +     int ret;
>> > +
>> > +     phi1_param.mfd = data->mfd;
>> > +     ret = plldig_calc_target_rate(rate, parent_rate, &phi1_param);
>> > +     if (ret)
>> > +             return ret;
>> > +
>> > +     val = readl(data->regs + PLLDIG_REG_PLLDV);
>> > +     val = FIELD_PREP(PLLDIG_REG_FIELD_MULT, phi1_param.mfd) |
>> > +           FIELD_PREP(PLLDIG_REG_FIELD_RFDPHI1,
>> phi1_param.rfdphi1);
>> > +
>> > +     writel(val, data->regs + PLLDIG_REG_PLLDV);
>> > +
>> > +     /* delay 200us make sure that old lock state is cleared */
>> > +     udelay(200);
>> > +
>> > +     /* Wait until PLL is locked or timeout (maximum 1000 usecs) */
>> > +     return readl_poll_timeout_atomic(data->regs + PLLDIG_REG_PLLSR,
>> cond,
>> > +                                      cond & PLLDIG_LOCK_MASK, 0,
>> > +                                      USEC_PER_MSEC); }
>> > +
>> > +static const struct clk_ops plldig_clk_ops = {
>> > +     .enable = plldig_enable,
>> > +     .disable = plldig_disable,
>> > +     .is_enabled = plldig_is_enabled,
>> > +     .recalc_rate = plldig_recalc_rate,
>> > +     .determine_rate = plldig_determine_rate,
>> > +     .set_rate = plldig_set_rate,
>> > +};
>> > +
>> > +static int plldig_clk_probe(struct platform_device *pdev) {
>> > +     struct clk_plldig *data;
>> > +     struct resource *mem;
>> > +     struct device *dev = &pdev->dev;
>> > +     int ret;
>> > +
>> > +     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> > +     if (!data)
>> > +             return -ENOMEM;
>> > +
>> > +     mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> > +     data->regs = devm_ioremap_resource(dev, mem);
>> > +     if (IS_ERR(data->regs))
>> > +             return PTR_ERR(data->regs);
>> > +
>> > +      /*
>> > +       * Support to get the best loop multiplication divider value
>> > +       * from DTS file, since this PLL can't changed this value on
>> > +       * the fly, write the fixed value.
>> > +       */
>> > +     ret = of_property_read_u32(dev->of_node, "best-mfd", &data->mfd);
>> > +     if (ret)
>> > +             data->mfd = 0x2c;
>> 
>> IMHO this is a really bad device tree binding. First it is not 
>> described anywhere,
>> ie it is missing in the dt-bindings file and second, to actually make 
>> use of the
>> "best-mfd" the user has to know the parent clock, the desired vco 
>> frequency
>> and have to calculate it by himself.
>> IMHO a better one would be something like "vco-frequency". Also you 
>> should
>> use the fractional divider to get better results. Using the fractional 
>> divider
>> almost any VCO frequency is possible (within a certain range which 
>> should be
>> checked [650 MHz to 1300 MHz]).
>> 
> 
> Yes, the fractional part can covered range is 27MHz, it can almost any
> VCO frequency.
> the fractional divider should be supported in this driver.
> 
> I also knew the device tree binding is bad specially way, but here just 
> want to
> provide a simple solution used to configure the MFD value for users 
> requirement.

Well, but once it is in the device tree, it is hard to change, so there 
should be no quick hacks, IMHO.

> So you think that should be use "vco-frequency" instead of the
> "best-mfd" in dts used to
> avoid user recalculate it(user may don’t know the parent rate)?

correct.

-michael

Patch
diff mbox series

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 0530bebfc25a..9f6b0196c604 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -218,6 +218,16 @@  config CLK_QORIQ
 	  This adds the clock driver support for Freescale QorIQ platforms
 	  using common clock framework.
 
+config CLK_LS1028A_PLLDIG
+        tristate "Clock driver for LS1028A Display output"
+        depends on ARCH_LAYERSCAPE || COMPILE_TEST
+        default ARCH_LAYERSCAPE
+        help
+          This driver support the Display output interfaces(LCD, DPHY) pixel clocks
+          of the QorIQ Layerscape LS1028A, as implemented TSMC CLN28HPM PLL. Not all
+          features of the PLL are currently supported by the driver. By default,
+          configured bypass mode with this PLL.
+
 config COMMON_CLK_XGENE
 	bool "Clock driver for APM XGene SoC"
 	default ARCH_XGENE
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 0138fb14e6f8..97d1e5bc6de5 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -43,6 +43,7 @@  obj-$(CONFIG_ARCH_NPCM7XX)	    	+= clk-npcm7xx.o
 obj-$(CONFIG_ARCH_NSPIRE)		+= clk-nspire.o
 obj-$(CONFIG_COMMON_CLK_OXNAS)		+= clk-oxnas.o
 obj-$(CONFIG_COMMON_CLK_PALMAS)		+= clk-palmas.o
+obj-$(CONFIG_CLK_LS1028A_PLLDIG)	+= clk-plldig.o
 obj-$(CONFIG_COMMON_CLK_PWM)		+= clk-pwm.o
 obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
 obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
diff --git a/drivers/clk/clk-plldig.c b/drivers/clk/clk-plldig.c
new file mode 100644
index 000000000000..f940a9d3d011
--- /dev/null
+++ b/drivers/clk/clk-plldig.c
@@ -0,0 +1,297 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP
+ *
+ * Clock driver for LS1028A Display output interfaces(LCD, DPHY).
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/bitfield.h>
+
+/* PLLDIG register offsets and bit masks */
+#define PLLDIG_REG_PLLSR            0x24
+#define PLLDIG_REG_PLLDV            0x28
+#define PLLDIG_REG_PLLFM            0x2c
+#define PLLDIG_REG_PLLFD            0x30
+#define PLLDIG_REG_PLLCAL1          0x38
+#define PLLDIG_REG_PLLCAL2          0x3c
+#define PLLDIG_LOCK_MASK            BIT(2)
+#define PLLDIG_REG_FIELD_SSCGBYP    BIT(30)
+#define PLLDIG_REG_FIELD_FDEN       BIT(30)
+#define PLLDIG_REG_FIELD_DTHDIS     GENMASK(17, 16)
+#define PLLDIG_REG_FIELD_MULT       GENMASK(7, 0)
+#define PLLDIG_REG_FIELD_RFDPHI1    GENMASK(30, 25)
+
+/* Minimum output clock frequency, in Hz */
+#define PHI1_MIN_FREQ 27000000
+
+/* Maximum output clock frequency, in Hz */
+#define PHI1_MAX_FREQ 600000000
+
+/* Maximum of the divider */
+#define MAX_RFDPHI1          63
+
+/*
+ * Clock configuration relationship between the PHI1 frequency(fpll_phi) and
+ * the output frequency of the PLL is determined by the PLLDV, according to
+ * the following equation:
+ * fpll_phi = (pll_ref * mfd) / div_rfdphi1
+ */
+struct plldig_phi1_param {
+	unsigned long rate;
+	unsigned int rfdphi1;
+	unsigned int mfd;
+};
+
+static const struct clk_parent_data parent_data[] = {
+	{.index = 0},
+};
+
+struct clk_plldig {
+	struct clk_hw hw;
+	void __iomem *regs;
+	unsigned int mfd;
+};
+
+#define to_clk_plldig(_hw)	container_of(_hw, struct clk_plldig, hw)
+
+static int plldig_enable(struct clk_hw *hw)
+{
+	struct clk_plldig *data = to_clk_plldig(hw);
+	u32 val;
+
+	val = readl(data->regs + PLLDIG_REG_PLLFM);
+	/*
+	 * Use Bypass mode with PLL off by default, the frequency overshoot
+	 * detector output was disable. SSCG Bypass mode should be enable.
+	 */
+	val |= PLLDIG_REG_FIELD_SSCGBYP;
+	writel(val, data->regs + PLLDIG_REG_PLLFM);
+
+	val = readl(data->regs + PLLDIG_REG_PLLFD);
+	/* Disable dither and Sigma delta modulation in bypass mode */
+	val |= FIELD_PREP(PLLDIG_REG_FIELD_FDEN, 0x1) |
+	       FIELD_PREP(PLLDIG_REG_FIELD_DTHDIS, 0x3);
+
+	writel(val, data->regs + PLLDIG_REG_PLLFD);
+
+	return 0;
+}
+
+static void plldig_disable(struct clk_hw *hw)
+{
+	struct clk_plldig *data = to_clk_plldig(hw);
+	u32 val;
+
+	val = readl(data->regs + PLLDIG_REG_PLLFM);
+
+	val &= ~PLLDIG_REG_FIELD_SSCGBYP;
+	val |= FIELD_PREP(PLLDIG_REG_FIELD_SSCGBYP, 0x0);
+
+	writel(val, data->regs + PLLDIG_REG_PLLFM);
+}
+
+static int plldig_is_enabled(struct clk_hw *hw)
+{
+	struct clk_plldig *data = to_clk_plldig(hw);
+
+	return (readl(data->regs + PLLDIG_REG_PLLFM) &
+			      PLLDIG_REG_FIELD_SSCGBYP);
+}
+
+static unsigned long plldig_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct clk_plldig *data = to_clk_plldig(hw);
+	u32 mult, div, val;
+
+	val = readl(data->regs + PLLDIG_REG_PLLDV);
+
+	/* Check if PLL is bypassed */
+	if (val & PLLDIG_REG_FIELD_SSCGBYP)
+		return parent_rate;
+
+	/* Checkout multiplication factor divider value */
+	mult = FIELD_GET(PLLDIG_REG_FIELD_MULT, val);
+
+	/* Checkout divider value of the output frequency */
+	div = FIELD_GET(PLLDIG_REG_FIELD_RFDPHI1, val);
+
+	return (parent_rate * mult) / div;
+}
+
+static int plldig_calc_target_rate(unsigned long target_rate,
+				   unsigned long parent_rate,
+				   struct plldig_phi1_param *phi1)
+{
+	unsigned int div, ret;
+	unsigned long round_rate;
+
+	/* Range limitation of the request target rate */
+	if (target_rate > PHI1_MAX_FREQ)
+		target_rate = PHI1_MAX_FREQ;
+	else if (target_rate < PHI1_MIN_FREQ)
+		target_rate = PHI1_MIN_FREQ;
+
+	/*
+	 * Firstly, check the request target rate whether is divisible
+	 * by the best VCO frequency.
+	 */
+	round_rate = parent_rate * phi1->mfd;
+	div = round_rate / target_rate;
+	if (!div || div > MAX_RFDPHI1)
+		return -EINVAL;
+
+	ret = round_rate % target_rate;
+	if (ret) {
+		/*
+		 * Rounded down the request target rate, VESA specifies
+		 * 0.5% pixel clock tolerance, therefore this algorithm
+		 * can able to compatible a lot of request rates within
+		 * range of the tolerance.
+		 */
+		round_rate += (target_rate / 2);
+		div = round_rate / target_rate;
+		if (!div || div > MAX_RFDPHI1)
+			return -EINVAL;
+	}
+
+	phi1->rfdphi1 = div;
+	phi1->rate = target_rate;
+
+	return 0;
+}
+
+static int plldig_determine_rate(struct clk_hw *hw,
+				 struct clk_rate_request *req)
+{
+	int ret;
+	unsigned long parent_rate;
+	struct clk_hw *parent;
+	struct plldig_phi1_param phi1_param;
+	struct clk_plldig *data = to_clk_plldig(hw);
+
+	if (!req->rate)
+		return -ERANGE;
+
+	phi1_param.mfd = data->mfd;
+	parent = clk_hw_get_parent(hw);
+	parent_rate = clk_hw_get_rate(parent);
+
+	ret = plldig_calc_target_rate(req->rate, parent_rate, &phi1_param);
+	if (ret)
+		return ret;
+
+	req->rate = phi1_param.rate;
+
+	return 0;
+}
+
+static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long parent_rate)
+{
+	struct clk_plldig *data = to_clk_plldig(hw);
+	struct plldig_phi1_param phi1_param;
+	unsigned int val, cond;
+	int ret;
+
+	phi1_param.mfd = data->mfd;
+	ret = plldig_calc_target_rate(rate, parent_rate, &phi1_param);
+	if (ret)
+		return ret;
+
+	val = readl(data->regs + PLLDIG_REG_PLLDV);
+	val = FIELD_PREP(PLLDIG_REG_FIELD_MULT, phi1_param.mfd) |
+	      FIELD_PREP(PLLDIG_REG_FIELD_RFDPHI1, phi1_param.rfdphi1);
+
+	writel(val, data->regs + PLLDIG_REG_PLLDV);
+
+	/* delay 200us make sure that old lock state is cleared */
+	udelay(200);
+
+	/* Wait until PLL is locked or timeout (maximum 1000 usecs) */
+	return readl_poll_timeout_atomic(data->regs + PLLDIG_REG_PLLSR, cond,
+					 cond & PLLDIG_LOCK_MASK, 0,
+					 USEC_PER_MSEC);
+}
+
+static const struct clk_ops plldig_clk_ops = {
+	.enable = plldig_enable,
+	.disable = plldig_disable,
+	.is_enabled = plldig_is_enabled,
+	.recalc_rate = plldig_recalc_rate,
+	.determine_rate = plldig_determine_rate,
+	.set_rate = plldig_set_rate,
+};
+
+static int plldig_clk_probe(struct platform_device *pdev)
+{
+	struct clk_plldig *data;
+	struct resource *mem;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(data->regs))
+		return PTR_ERR(data->regs);
+
+	 /*
+	  * Support to get the best loop multiplication divider value
+	  * from DTS file, since this PLL can't changed this value on
+	  * the fly, write the fixed value.
+	  */
+	ret = of_property_read_u32(dev->of_node, "best-mfd", &data->mfd);
+	if (ret)
+		data->mfd = 0x2c;
+
+	writel(data->mfd, data->regs + PLLDIG_REG_PLLDV);
+
+	data->hw.init = CLK_HW_INIT_PARENTS_DATA("dpclk",
+						 parent_data,
+						 &plldig_clk_ops,
+						 0);
+
+	ret = devm_clk_hw_register(dev, &data->hw);
+	if (ret) {
+		dev_err(dev, "failed to register %s clock\n",
+						dev->of_node->name);
+		return ret;
+	}
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					   &data->hw);
+}
+
+static const struct of_device_id plldig_clk_id[] = {
+	{ .compatible = "fsl,ls1028a-plldig"},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, plldig_clk_id);
+
+static struct platform_driver plldig_clk_driver = {
+	.driver = {
+		.name = "plldig-clock",
+		.of_match_table = plldig_clk_id,
+	},
+	.probe = plldig_clk_probe,
+};
+module_platform_driver(plldig_clk_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Wen He <wen.he_1@nxp.com>");
+MODULE_DESCRIPTION("LS1028A Display output interface pixel clock driver");