[v3,03/10] mfd: mtk-mmsys: Add mmsys driver
diff mbox

Message ID e0894c97775e46ce6d9a441dc05e2e2479a4b612.1524820923.git.mbrugger@suse.com
State New
Headers show

Commit Message

Matthias Brugger April 27, 2018, 9:23 a.m. UTC
From: Matthias Brugger <mbrugger@suse.com>

The MMSYS subsystem includes clocks and drm components.
This patch adds a MFD device to probe both drivers from the same
device tree compatible.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
 drivers/mfd/Kconfig     |  9 ++++++
 drivers/mfd/Makefile    |  2 ++
 drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 drivers/mfd/mtk-mmsys.c

Comments

Lee Jones April 30, 2018, 10:18 a.m. UTC | #1
On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:

> From: Matthias Brugger <mbrugger@suse.com>
> 
> The MMSYS subsystem includes clocks and drm components.
> This patch adds a MFD device to probe both drivers from the same
> device tree compatible.
> 
> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> ---
>  drivers/mfd/Kconfig     |  9 ++++++
>  drivers/mfd/Makefile    |  2 ++
>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 90 insertions(+)
>  create mode 100644 drivers/mfd/mtk-mmsys.c
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b860eb5aa194..d23a3b9a2c58 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
>  	help
>  	  Select this if your MC13xxx is connected via an I2C bus.
>  
> +config MFD_MEDIATEK_MMSYS
> +	tristate "Mediatek MMSYS interface"
> +	select MFD_CORE
> +	select REGMAP_MMIO
> +	help
> +	  Select this if you have a MMSYS subsystem in your SoC. The
> +	  MMSYS subsystem has at least a clock driver part and some
> +	  DRM components.
> +
>  config MFD_MXS_LRADC
>  	tristate "Freescale i.MX23/i.MX28 LRADC"
>  	depends on ARCH_MXS || COMPILE_TEST
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9d2cf0d32ef..b96118bd68d9 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>  
> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
> +
>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>  
>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
> new file mode 100644
> index 000000000000..c802343fb1c6
> --- /dev/null
> +++ b/drivers/mfd/mtk-mmsys.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/*
> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
> + *
> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
> + *
> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/mfd/core.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +enum {
> +	MMSYS_MT2701 = 1,
> +};
> +
> +static const struct mfd_cell mmsys_mt2701_devs[] = {
> +	{ .name = "clk-mt2701-mm", },
> +	{ .name = "drm-mt2701-mm", },
> +};
> +
> +static int mmsys_probe(struct platform_device *pdev)
> +{
> +	const struct mfd_cell *mmsys_cells;
> +	int nr_cells;
> +	long id;
> +	int ret;
> +
> +	id = (long) of_device_get_match_data(&pdev->dev);
> +	if (!id) {
> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
> +		return -EINVAL;
> +	}
> +
> +	switch (id) {
> +	case MMSYS_MT2701:
> +		mmsys_cells = mmsys_mt2701_devs;
> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
> +		break;
> +	default:
> +		return -ENODEV;
> +	}
> +
> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
> +					NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +};

This driver is pretty pointless.  It doesn't actually do anything.

I think you just want to use "simple-mfd" instead.

> +static const struct of_device_id of_match_mmsys[] = {
> +	{ .compatible = "mediatek,mt2701-mmsys",
> +	  .data = (void *) MMSYS_MT2701,
> +	},
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver mmsys_drv = {
> +	.probe = mmsys_probe,
> +	.driver = {
> +		.name = "mediatek-mmysys",
> +		.of_match_table = of_match_ptr(of_match_mmsys),
> +	},
> +};
> +
> +builtin_platform_driver(mmsys_drv);
> +
> +MODULE_DESCRIPTION("Mediatek MMSYS multi-function driver");
> +MODULE_LICENSE("GPL");
Sean Wang May 24, 2018, 2:52 a.m. UTC | #2
On Mon, 2018-04-30 at 11:18 +0100, Lee Jones wrote:
> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
> 
> > From: Matthias Brugger <mbrugger@suse.com>
> > 
> > The MMSYS subsystem includes clocks and drm components.
> > This patch adds a MFD device to probe both drivers from the same
> > device tree compatible.
> > 
> > Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> > ---
> >  drivers/mfd/Kconfig     |  9 ++++++
> >  drivers/mfd/Makefile    |  2 ++
> >  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++

[ ... ]

> > +};
> 
> This driver is pretty pointless.  It doesn't actually do anything.
> 
> I think you just want to use "simple-mfd" instead.
> 


Hi, Matthias

Why not embedded a platform_device_register_data call into existent
MMSYS driver ?

It looks elegant and makes sense that mmsys device is being as parent
device for all its DRM components device and no need to create an
additional node representing the same device with mmsys simply in order
to probe its DRM components.

I'm planing to send a bunch of HDMI, MIPI related to MMSYS nodes for
MT7623 SoC when 4.18 rc1 comes out, so we should want to solve the
dt-binding violation issue first.

Though there are two same mmsys-compatible strings involving in dts
though, it seems that hdmi still can work fine in my setup.

	Sean


> > +static const struct of_device_id of_match_mmsys[] = {
> > +	{ .compatible = "mediatek,mt2701-mmsys",
> > +	  .data = (void *) MMSYS_MT2701,
> > +	},
> > +	{ /* sentinel */ },
> > +};
> > +
> > +static struct platform_driver mmsys_drv = {
> > +	.probe = mmsys_probe,
> > +	.driver = {
> > +		.name = "mediatek-mmysys",
> > +		.of_match_table = of_match_ptr(of_match_mmsys),
> > +	},
> > +};
> > +
> > +builtin_platform_driver(mmsys_drv);
> > +
> > +MODULE_DESCRIPTION("Mediatek MMSYS multi-function driver");
> > +MODULE_LICENSE("GPL");
>
Matthias Brugger June 25, 2018, 3:33 p.m. UTC | #3
On 30/04/18 12:18, Lee Jones wrote:
> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
> 
>> From: Matthias Brugger <mbrugger@suse.com>
>>
>> The MMSYS subsystem includes clocks and drm components.
>> This patch adds a MFD device to probe both drivers from the same
>> device tree compatible.
>>
>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>> ---
>>  drivers/mfd/Kconfig     |  9 ++++++
>>  drivers/mfd/Makefile    |  2 ++
>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 90 insertions(+)
>>  create mode 100644 drivers/mfd/mtk-mmsys.c
>>
>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>> index b860eb5aa194..d23a3b9a2c58 100644
>> --- a/drivers/mfd/Kconfig
>> +++ b/drivers/mfd/Kconfig
>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
>>  	help
>>  	  Select this if your MC13xxx is connected via an I2C bus.
>>  
>> +config MFD_MEDIATEK_MMSYS
>> +	tristate "Mediatek MMSYS interface"
>> +	select MFD_CORE
>> +	select REGMAP_MMIO
>> +	help
>> +	  Select this if you have a MMSYS subsystem in your SoC. The
>> +	  MMSYS subsystem has at least a clock driver part and some
>> +	  DRM components.
>> +
>>  config MFD_MXS_LRADC
>>  	tristate "Freescale i.MX23/i.MX28 LRADC"
>>  	depends on ARCH_MXS || COMPILE_TEST
>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>> index d9d2cf0d32ef..b96118bd68d9 100644
>> --- a/drivers/mfd/Makefile
>> +++ b/drivers/mfd/Makefile
>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>>  
>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
>> +
>>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>>  
>>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
>> new file mode 100644
>> index 000000000000..c802343fb1c6
>> --- /dev/null
>> +++ b/drivers/mfd/mtk-mmsys.c
>> @@ -0,0 +1,79 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +
>> +/*
>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
>> + *
>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
>> + *
>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/mfd/core.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +
>> +enum {
>> +	MMSYS_MT2701 = 1,
>> +};
>> +
>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
>> +	{ .name = "clk-mt2701-mm", },
>> +	{ .name = "drm-mt2701-mm", },
>> +};
>> +
>> +static int mmsys_probe(struct platform_device *pdev)
>> +{
>> +	const struct mfd_cell *mmsys_cells;
>> +	int nr_cells;
>> +	long id;
>> +	int ret;
>> +
>> +	id = (long) of_device_get_match_data(&pdev->dev);
>> +	if (!id) {
>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	switch (id) {
>> +	case MMSYS_MT2701:
>> +		mmsys_cells = mmsys_mt2701_devs;
>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
>> +		break;
>> +	default:
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
>> +					NULL, 0, NULL);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +};
> 
> This driver is pretty pointless.  It doesn't actually do anything.
> 
> I think you just want to use "simple-mfd" instead.
> 

I think the problem is, that right now we have two drivers which use the same
devicetree binding, which are clk and drm driver. With a simple-mfd we would
need two compatibles, and this would break backwards compatibility.

Regards,
Matthias
Lee Jones July 3, 2018, 7:11 a.m. UTC | #4
On Mon, 25 Jun 2018, Matthias Brugger wrote:
> On 30/04/18 12:18, Lee Jones wrote:
> > On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
> > 
> >> From: Matthias Brugger <mbrugger@suse.com>
> >>
> >> The MMSYS subsystem includes clocks and drm components.
> >> This patch adds a MFD device to probe both drivers from the same
> >> device tree compatible.
> >>
> >> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> >> ---
> >>  drivers/mfd/Kconfig     |  9 ++++++
> >>  drivers/mfd/Makefile    |  2 ++
> >>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
> >>  3 files changed, 90 insertions(+)
> >>  create mode 100644 drivers/mfd/mtk-mmsys.c
> >>
> >> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> >> index b860eb5aa194..d23a3b9a2c58 100644
> >> --- a/drivers/mfd/Kconfig
> >> +++ b/drivers/mfd/Kconfig
> >> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
> >>  	help
> >>  	  Select this if your MC13xxx is connected via an I2C bus.
> >>  
> >> +config MFD_MEDIATEK_MMSYS
> >> +	tristate "Mediatek MMSYS interface"
> >> +	select MFD_CORE
> >> +	select REGMAP_MMIO
> >> +	help
> >> +	  Select this if you have a MMSYS subsystem in your SoC. The
> >> +	  MMSYS subsystem has at least a clock driver part and some
> >> +	  DRM components.
> >> +
> >>  config MFD_MXS_LRADC
> >>  	tristate "Freescale i.MX23/i.MX28 LRADC"
> >>  	depends on ARCH_MXS || COMPILE_TEST
> >> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> >> index d9d2cf0d32ef..b96118bd68d9 100644
> >> --- a/drivers/mfd/Makefile
> >> +++ b/drivers/mfd/Makefile
> >> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
> >>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
> >>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
> >>  
> >> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
> >> +
> >>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
> >>  
> >>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
> >> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
> >> new file mode 100644
> >> index 000000000000..c802343fb1c6
> >> --- /dev/null
> >> +++ b/drivers/mfd/mtk-mmsys.c
> >> @@ -0,0 +1,79 @@
> >> +// SPDX-License-Identifier: GPL-2.0+
> >> +
> >> +/*
> >> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
> >> + *
> >> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
> >> + *
> >> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
> >> + */
> >> +
> >> +#include <linux/module.h>
> >> +#include <linux/init.h>
> >> +#include <linux/mfd/core.h>
> >> +#include <linux/of.h>
> >> +#include <linux/of_address.h>
> >> +#include <linux/of_device.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/regmap.h>
> >> +
> >> +enum {
> >> +	MMSYS_MT2701 = 1,
> >> +};
> >> +
> >> +static const struct mfd_cell mmsys_mt2701_devs[] = {
> >> +	{ .name = "clk-mt2701-mm", },
> >> +	{ .name = "drm-mt2701-mm", },
> >> +};
> >> +
> >> +static int mmsys_probe(struct platform_device *pdev)
> >> +{
> >> +	const struct mfd_cell *mmsys_cells;
> >> +	int nr_cells;
> >> +	long id;
> >> +	int ret;
> >> +
> >> +	id = (long) of_device_get_match_data(&pdev->dev);
> >> +	if (!id) {
> >> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
> >> +		return -EINVAL;
> >> +	}
> >> +
> >> +	switch (id) {
> >> +	case MMSYS_MT2701:
> >> +		mmsys_cells = mmsys_mt2701_devs;
> >> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
> >> +		break;
> >> +	default:
> >> +		return -ENODEV;
> >> +	}
> >> +
> >> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
> >> +					NULL, 0, NULL);
> >> +	if (ret) {
> >> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	return 0;
> >> +};
> > 
> > This driver is pretty pointless.  It doesn't actually do anything.
> > 
> > I think you just want to use "simple-mfd" instead.
> > 
> 
> I think the problem is, that right now we have two drivers which use the same
> devicetree binding, which are clk and drm driver. With a simple-mfd we would
> need two compatibles, and this would break backwards compatibility.

So what functionality does this driver provide you with that you do
not have currently?
Matthias Brugger July 4, 2018, 4:17 p.m. UTC | #5
On 03/07/18 09:11, Lee Jones wrote:
> On Mon, 25 Jun 2018, Matthias Brugger wrote:
>> On 30/04/18 12:18, Lee Jones wrote:
>>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
>>>
>>>> From: Matthias Brugger <mbrugger@suse.com>
>>>>
>>>> The MMSYS subsystem includes clocks and drm components.
>>>> This patch adds a MFD device to probe both drivers from the same
>>>> device tree compatible.
>>>>
>>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>>>> ---
>>>>  drivers/mfd/Kconfig     |  9 ++++++
>>>>  drivers/mfd/Makefile    |  2 ++
>>>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 90 insertions(+)
>>>>  create mode 100644 drivers/mfd/mtk-mmsys.c
>>>>
>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>> index b860eb5aa194..d23a3b9a2c58 100644
>>>> --- a/drivers/mfd/Kconfig
>>>> +++ b/drivers/mfd/Kconfig
>>>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
>>>>  	help
>>>>  	  Select this if your MC13xxx is connected via an I2C bus.
>>>>  
>>>> +config MFD_MEDIATEK_MMSYS
>>>> +	tristate "Mediatek MMSYS interface"
>>>> +	select MFD_CORE
>>>> +	select REGMAP_MMIO
>>>> +	help
>>>> +	  Select this if you have a MMSYS subsystem in your SoC. The
>>>> +	  MMSYS subsystem has at least a clock driver part and some
>>>> +	  DRM components.
>>>> +
>>>>  config MFD_MXS_LRADC
>>>>  	tristate "Freescale i.MX23/i.MX28 LRADC"
>>>>  	depends on ARCH_MXS || COMPILE_TEST
>>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>>>> index d9d2cf0d32ef..b96118bd68d9 100644
>>>> --- a/drivers/mfd/Makefile
>>>> +++ b/drivers/mfd/Makefile
>>>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>>>>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>>>>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>>>>  
>>>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
>>>> +
>>>>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>>>>  
>>>>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
>>>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
>>>> new file mode 100644
>>>> index 000000000000..c802343fb1c6
>>>> --- /dev/null
>>>> +++ b/drivers/mfd/mtk-mmsys.c
>>>> @@ -0,0 +1,79 @@
>>>> +// SPDX-License-Identifier: GPL-2.0+
>>>> +
>>>> +/*
>>>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
>>>> + *
>>>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
>>>> + *
>>>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
>>>> + */
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include <linux/init.h>
>>>> +#include <linux/mfd/core.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_address.h>
>>>> +#include <linux/of_device.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/regmap.h>
>>>> +
>>>> +enum {
>>>> +	MMSYS_MT2701 = 1,
>>>> +};
>>>> +
>>>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
>>>> +	{ .name = "clk-mt2701-mm", },
>>>> +	{ .name = "drm-mt2701-mm", },
>>>> +};
>>>> +
>>>> +static int mmsys_probe(struct platform_device *pdev)
>>>> +{
>>>> +	const struct mfd_cell *mmsys_cells;
>>>> +	int nr_cells;
>>>> +	long id;
>>>> +	int ret;
>>>> +
>>>> +	id = (long) of_device_get_match_data(&pdev->dev);
>>>> +	if (!id) {
>>>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	switch (id) {
>>>> +	case MMSYS_MT2701:
>>>> +		mmsys_cells = mmsys_mt2701_devs;
>>>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
>>>> +		break;
>>>> +	default:
>>>> +		return -ENODEV;
>>>> +	}
>>>> +
>>>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
>>>> +					NULL, 0, NULL);
>>>> +	if (ret) {
>>>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +};
>>>
>>> This driver is pretty pointless.  It doesn't actually do anything.
>>>
>>> I think you just want to use "simple-mfd" instead.
>>>
>>
>> I think the problem is, that right now we have two drivers which use the same
>> devicetree binding, which are clk and drm driver. With a simple-mfd we would
>> need two compatibles, and this would break backwards compatibility.
> 
> So what functionality does this driver provide you with that you do
> not have currently?
> 

I'm not sure if I get your question. Point is, that the MMSYS implementation for
mt8173 is broken, as it assumes that we can probe two drivers with the
mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
understand it was a bug. So older devicetrees use just on mt8173-mmsys
compatible in ther DTB.

I would like to keep backwards compatibility for the device tree, that's why I
was searching for a solution where we can probe two drivers and came up with
this mfd solution.

So no new functionality, the clk driver provides the clock the drm components need.

Regards,
Matthias
Lee Jones July 4, 2018, 4:45 p.m. UTC | #6
On Wed, 04 Jul 2018, Matthias Brugger wrote:

> 
> 
> On 03/07/18 09:11, Lee Jones wrote:
> > On Mon, 25 Jun 2018, Matthias Brugger wrote:
> >> On 30/04/18 12:18, Lee Jones wrote:
> >>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
> >>>
> >>>> From: Matthias Brugger <mbrugger@suse.com>
> >>>>
> >>>> The MMSYS subsystem includes clocks and drm components.
> >>>> This patch adds a MFD device to probe both drivers from the same
> >>>> device tree compatible.
> >>>>
> >>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> >>>> ---
> >>>>  drivers/mfd/Kconfig     |  9 ++++++
> >>>>  drivers/mfd/Makefile    |  2 ++
> >>>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
> >>>>  3 files changed, 90 insertions(+)
> >>>>  create mode 100644 drivers/mfd/mtk-mmsys.c
> >>>>
> >>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> >>>> index b860eb5aa194..d23a3b9a2c58 100644
> >>>> --- a/drivers/mfd/Kconfig
> >>>> +++ b/drivers/mfd/Kconfig
> >>>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
> >>>>  	help
> >>>>  	  Select this if your MC13xxx is connected via an I2C bus.
> >>>>  
> >>>> +config MFD_MEDIATEK_MMSYS
> >>>> +	tristate "Mediatek MMSYS interface"
> >>>> +	select MFD_CORE
> >>>> +	select REGMAP_MMIO
> >>>> +	help
> >>>> +	  Select this if you have a MMSYS subsystem in your SoC. The
> >>>> +	  MMSYS subsystem has at least a clock driver part and some
> >>>> +	  DRM components.
> >>>> +
> >>>>  config MFD_MXS_LRADC
> >>>>  	tristate "Freescale i.MX23/i.MX28 LRADC"
> >>>>  	depends on ARCH_MXS || COMPILE_TEST
> >>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> >>>> index d9d2cf0d32ef..b96118bd68d9 100644
> >>>> --- a/drivers/mfd/Makefile
> >>>> +++ b/drivers/mfd/Makefile
> >>>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
> >>>>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
> >>>>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
> >>>>  
> >>>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
> >>>> +
> >>>>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
> >>>>  
> >>>>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
> >>>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
> >>>> new file mode 100644
> >>>> index 000000000000..c802343fb1c6
> >>>> --- /dev/null
> >>>> +++ b/drivers/mfd/mtk-mmsys.c
> >>>> @@ -0,0 +1,79 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0+
> >>>> +
> >>>> +/*
> >>>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
> >>>> + *
> >>>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
> >>>> + *
> >>>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
> >>>> + */
> >>>> +
> >>>> +#include <linux/module.h>
> >>>> +#include <linux/init.h>
> >>>> +#include <linux/mfd/core.h>
> >>>> +#include <linux/of.h>
> >>>> +#include <linux/of_address.h>
> >>>> +#include <linux/of_device.h>
> >>>> +#include <linux/platform_device.h>
> >>>> +#include <linux/regmap.h>
> >>>> +
> >>>> +enum {
> >>>> +	MMSYS_MT2701 = 1,
> >>>> +};
> >>>> +
> >>>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
> >>>> +	{ .name = "clk-mt2701-mm", },
> >>>> +	{ .name = "drm-mt2701-mm", },
> >>>> +};
> >>>> +
> >>>> +static int mmsys_probe(struct platform_device *pdev)
> >>>> +{
> >>>> +	const struct mfd_cell *mmsys_cells;
> >>>> +	int nr_cells;
> >>>> +	long id;
> >>>> +	int ret;
> >>>> +
> >>>> +	id = (long) of_device_get_match_data(&pdev->dev);
> >>>> +	if (!id) {
> >>>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
> >>>> +		return -EINVAL;
> >>>> +	}
> >>>> +
> >>>> +	switch (id) {
> >>>> +	case MMSYS_MT2701:
> >>>> +		mmsys_cells = mmsys_mt2701_devs;
> >>>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
> >>>> +		break;
> >>>> +	default:
> >>>> +		return -ENODEV;
> >>>> +	}
> >>>> +
> >>>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
> >>>> +					NULL, 0, NULL);
> >>>> +	if (ret) {
> >>>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
> >>>> +		return ret;
> >>>> +	}
> >>>> +
> >>>> +	return 0;
> >>>> +};
> >>>
> >>> This driver is pretty pointless.  It doesn't actually do anything.
> >>>
> >>> I think you just want to use "simple-mfd" instead.
> >>>
> >>
> >> I think the problem is, that right now we have two drivers which use the same
> >> devicetree binding, which are clk and drm driver. With a simple-mfd we would
> >> need two compatibles, and this would break backwards compatibility.
> > 
> > So what functionality does this driver provide you with that you do
> > not have currently?
> > 
> 
> I'm not sure if I get your question. Point is, that the MMSYS implementation for
> mt8173 is broken, as it assumes that we can probe two drivers with the
> mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
> understand it was a bug. So older devicetrees use just on mt8173-mmsys
> compatible in ther DTB.

Okay, that is what I was getting at.  Thanks for the explanation.

Do you have a datasheet I can look at?

> I would like to keep backwards compatibility for the device tree, that's why I
> was searching for a solution where we can probe two drivers and came up with
> this mfd solution.
>
> So no new functionality, the clk driver provides the clock the drm components need.
Chen-Yu Tsai July 4, 2018, 4:52 p.m. UTC | #7
On Thu, Jul 5, 2018 at 12:17 AM, Matthias Brugger <mbrugger@suse.com> wrote:
>
>
> On 03/07/18 09:11, Lee Jones wrote:
>> On Mon, 25 Jun 2018, Matthias Brugger wrote:
>>> On 30/04/18 12:18, Lee Jones wrote:
>>>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
>>>>
>>>>> From: Matthias Brugger <mbrugger@suse.com>
>>>>>
>>>>> The MMSYS subsystem includes clocks and drm components.
>>>>> This patch adds a MFD device to probe both drivers from the same
>>>>> device tree compatible.
>>>>>
>>>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>>>>> ---
>>>>>  drivers/mfd/Kconfig     |  9 ++++++
>>>>>  drivers/mfd/Makefile    |  2 ++
>>>>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>  3 files changed, 90 insertions(+)
>>>>>  create mode 100644 drivers/mfd/mtk-mmsys.c
>>>>>
>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>>> index b860eb5aa194..d23a3b9a2c58 100644
>>>>> --- a/drivers/mfd/Kconfig
>>>>> +++ b/drivers/mfd/Kconfig
>>>>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
>>>>>    help
>>>>>      Select this if your MC13xxx is connected via an I2C bus.
>>>>>
>>>>> +config MFD_MEDIATEK_MMSYS
>>>>> +  tristate "Mediatek MMSYS interface"
>>>>> +  select MFD_CORE
>>>>> +  select REGMAP_MMIO
>>>>> +  help
>>>>> +    Select this if you have a MMSYS subsystem in your SoC. The
>>>>> +    MMSYS subsystem has at least a clock driver part and some
>>>>> +    DRM components.
>>>>> +
>>>>>  config MFD_MXS_LRADC
>>>>>    tristate "Freescale i.MX23/i.MX28 LRADC"
>>>>>    depends on ARCH_MXS || COMPILE_TEST
>>>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>>>>> index d9d2cf0d32ef..b96118bd68d9 100644
>>>>> --- a/drivers/mfd/Makefile
>>>>> +++ b/drivers/mfd/Makefile
>>>>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)        += mc13xxx-core.o
>>>>>  obj-$(CONFIG_MFD_MC13XXX_SPI)     += mc13xxx-spi.o
>>>>>  obj-$(CONFIG_MFD_MC13XXX_I2C)     += mc13xxx-i2c.o
>>>>>
>>>>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
>>>>> +
>>>>>  obj-$(CONFIG_MFD_CORE)            += mfd-core.o
>>>>>
>>>>>  obj-$(CONFIG_EZX_PCAP)            += ezx-pcap.o
>>>>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
>>>>> new file mode 100644
>>>>> index 000000000000..c802343fb1c6
>>>>> --- /dev/null
>>>>> +++ b/drivers/mfd/mtk-mmsys.c
>>>>> @@ -0,0 +1,79 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0+
>>>>> +
>>>>> +/*
>>>>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
>>>>> + *
>>>>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
>>>>> + *
>>>>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
>>>>> + */
>>>>> +
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/init.h>
>>>>> +#include <linux/mfd/core.h>
>>>>> +#include <linux/of.h>
>>>>> +#include <linux/of_address.h>
>>>>> +#include <linux/of_device.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +#include <linux/regmap.h>
>>>>> +
>>>>> +enum {
>>>>> +  MMSYS_MT2701 = 1,
>>>>> +};
>>>>> +
>>>>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
>>>>> +  { .name = "clk-mt2701-mm", },
>>>>> +  { .name = "drm-mt2701-mm", },
>>>>> +};
>>>>> +
>>>>> +static int mmsys_probe(struct platform_device *pdev)
>>>>> +{
>>>>> +  const struct mfd_cell *mmsys_cells;
>>>>> +  int nr_cells;
>>>>> +  long id;
>>>>> +  int ret;
>>>>> +
>>>>> +  id = (long) of_device_get_match_data(&pdev->dev);
>>>>> +  if (!id) {
>>>>> +          dev_err(&pdev->dev, "of_device_get match_data() failed\n");
>>>>> +          return -EINVAL;
>>>>> +  }
>>>>> +
>>>>> +  switch (id) {
>>>>> +  case MMSYS_MT2701:
>>>>> +          mmsys_cells = mmsys_mt2701_devs;
>>>>> +          nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
>>>>> +          break;
>>>>> +  default:
>>>>> +          return -ENODEV;
>>>>> +  }
>>>>> +
>>>>> +  ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
>>>>> +                                  NULL, 0, NULL);
>>>>> +  if (ret) {
>>>>> +          dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
>>>>> +          return ret;
>>>>> +  }
>>>>> +
>>>>> +  return 0;
>>>>> +};
>>>>
>>>> This driver is pretty pointless.  It doesn't actually do anything.
>>>>
>>>> I think you just want to use "simple-mfd" instead.
>>>>
>>>
>>> I think the problem is, that right now we have two drivers which use the same
>>> devicetree binding, which are clk and drm driver. With a simple-mfd we would
>>> need two compatibles, and this would break backwards compatibility.
>>
>> So what functionality does this driver provide you with that you do
>> not have currently?
>>
>
> I'm not sure if I get your question. Point is, that the MMSYS implementation for
> mt8173 is broken, as it assumes that we can probe two drivers with the
> mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
> understand it was a bug. So older devicetrees use just on mt8173-mmsys
> compatible in ther DTB.

This works probably because the clk driver is using CLK_OF_DECLARE, which
does not use the device model (i.e. no attached struct dev). So later on,
when the device model scans and adds this device, it's considered not
probed yet, and the drm driver will probe.

This breaks horribly if you try to move the clk driver to a platform
device driver based implementation. On the other hand, if you need the
clk in early init, you can't use a platform or mfd device.

Regards
ChenYu

>
> I would like to keep backwards compatibility for the device tree, that's why I
> was searching for a solution where we can probe two drivers and came up with
> this mfd solution.
>
> So no new functionality, the clk driver provides the clock the drm components need.
>
> Regards,
> Matthias
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Matthias Brugger July 5, 2018, 11:25 a.m. UTC | #8
On 04/07/18 18:45, Lee Jones wrote:
> On Wed, 04 Jul 2018, Matthias Brugger wrote:
> 
>>
>>
>> On 03/07/18 09:11, Lee Jones wrote:
>>> On Mon, 25 Jun 2018, Matthias Brugger wrote:
>>>> On 30/04/18 12:18, Lee Jones wrote:
>>>>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
>>>>>
>>>>>> From: Matthias Brugger <mbrugger@suse.com>
>>>>>>
>>>>>> The MMSYS subsystem includes clocks and drm components.
>>>>>> This patch adds a MFD device to probe both drivers from the same
>>>>>> device tree compatible.
>>>>>>
>>>>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>>>>>> ---
>>>>>>  drivers/mfd/Kconfig     |  9 ++++++
>>>>>>  drivers/mfd/Makefile    |  2 ++
>>>>>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>>  3 files changed, 90 insertions(+)
>>>>>>  create mode 100644 drivers/mfd/mtk-mmsys.c
>>>>>>
>>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>>>> index b860eb5aa194..d23a3b9a2c58 100644
>>>>>> --- a/drivers/mfd/Kconfig
>>>>>> +++ b/drivers/mfd/Kconfig
>>>>>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
>>>>>>  	help
>>>>>>  	  Select this if your MC13xxx is connected via an I2C bus.
>>>>>>  
>>>>>> +config MFD_MEDIATEK_MMSYS
>>>>>> +	tristate "Mediatek MMSYS interface"
>>>>>> +	select MFD_CORE
>>>>>> +	select REGMAP_MMIO
>>>>>> +	help
>>>>>> +	  Select this if you have a MMSYS subsystem in your SoC. The
>>>>>> +	  MMSYS subsystem has at least a clock driver part and some
>>>>>> +	  DRM components.
>>>>>> +
>>>>>>  config MFD_MXS_LRADC
>>>>>>  	tristate "Freescale i.MX23/i.MX28 LRADC"
>>>>>>  	depends on ARCH_MXS || COMPILE_TEST
>>>>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>>>>>> index d9d2cf0d32ef..b96118bd68d9 100644
>>>>>> --- a/drivers/mfd/Makefile
>>>>>> +++ b/drivers/mfd/Makefile
>>>>>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>>>>>>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>>>>>>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>>>>>>  
>>>>>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
>>>>>> +
>>>>>>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>>>>>>  
>>>>>>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
>>>>>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..c802343fb1c6
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/mfd/mtk-mmsys.c
>>>>>> @@ -0,0 +1,79 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0+
>>>>>> +
>>>>>> +/*
>>>>>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
>>>>>> + *
>>>>>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
>>>>>> + *
>>>>>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
>>>>>> + */
>>>>>> +
>>>>>> +#include <linux/module.h>
>>>>>> +#include <linux/init.h>
>>>>>> +#include <linux/mfd/core.h>
>>>>>> +#include <linux/of.h>
>>>>>> +#include <linux/of_address.h>
>>>>>> +#include <linux/of_device.h>
>>>>>> +#include <linux/platform_device.h>
>>>>>> +#include <linux/regmap.h>
>>>>>> +
>>>>>> +enum {
>>>>>> +	MMSYS_MT2701 = 1,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
>>>>>> +	{ .name = "clk-mt2701-mm", },
>>>>>> +	{ .name = "drm-mt2701-mm", },
>>>>>> +};
>>>>>> +
>>>>>> +static int mmsys_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> +	const struct mfd_cell *mmsys_cells;
>>>>>> +	int nr_cells;
>>>>>> +	long id;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	id = (long) of_device_get_match_data(&pdev->dev);
>>>>>> +	if (!id) {
>>>>>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
>>>>>> +		return -EINVAL;
>>>>>> +	}
>>>>>> +
>>>>>> +	switch (id) {
>>>>>> +	case MMSYS_MT2701:
>>>>>> +		mmsys_cells = mmsys_mt2701_devs;
>>>>>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
>>>>>> +		break;
>>>>>> +	default:
>>>>>> +		return -ENODEV;
>>>>>> +	}
>>>>>> +
>>>>>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
>>>>>> +					NULL, 0, NULL);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	return 0;
>>>>>> +};
>>>>>
>>>>> This driver is pretty pointless.  It doesn't actually do anything.
>>>>>
>>>>> I think you just want to use "simple-mfd" instead.
>>>>>
>>>>
>>>> I think the problem is, that right now we have two drivers which use the same
>>>> devicetree binding, which are clk and drm driver. With a simple-mfd we would
>>>> need two compatibles, and this would break backwards compatibility.
>>>
>>> So what functionality does this driver provide you with that you do
>>> not have currently?
>>>
>>
>> I'm not sure if I get your question. Point is, that the MMSYS implementation for
>> mt8173 is broken, as it assumes that we can probe two drivers with the
>> mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
>> understand it was a bug. So older devicetrees use just on mt8173-mmsys
>> compatible in ther DTB.
> 
> Okay, that is what I was getting at.  Thanks for the explanation.
> 
> Do you have a datasheet I can look at?
> 

Unfortunately there is no datasheet you can get without a NDA. The only public
available information I'm aware of is for the (not upstream supported) 96board
[1]. And it's only the register description. You can find some more explanation
about the MMSYS in older threads which tried to solve the very same problem [2]

Regards,
Matthias


[1]
https://www.96boards.org/documentation/consumer/mediatekx20/additional-docs/docs/MT6797_Register_Table_Part_2.pdf
[2] http://lists.infradead.org/pipermail/linux-mediatek/2017-October/010979.html

>> I would like to keep backwards compatibility for the device tree, that's why I
>> was searching for a solution where we can probe two drivers and came up with
>> this mfd solution.
>>
>> So no new functionality, the clk driver provides the clock the drm components need.
>
Lee Jones July 5, 2018, 12:22 p.m. UTC | #9
On Thu, 05 Jul 2018, Matthias Brugger wrote:
> On 04/07/18 18:45, Lee Jones wrote:
> > On Wed, 04 Jul 2018, Matthias Brugger wrote:
> >> On 03/07/18 09:11, Lee Jones wrote:
> >>> On Mon, 25 Jun 2018, Matthias Brugger wrote:
> >>>> On 30/04/18 12:18, Lee Jones wrote:
> >>>>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
> >>>>>
> >>>>>> From: Matthias Brugger <mbrugger@suse.com>
> >>>>>>
> >>>>>> The MMSYS subsystem includes clocks and drm components.
> >>>>>> This patch adds a MFD device to probe both drivers from the same
> >>>>>> device tree compatible.
> >>>>>>
> >>>>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> >>>>>> ---
> >>>>>>  drivers/mfd/Kconfig     |  9 ++++++
> >>>>>>  drivers/mfd/Makefile    |  2 ++
> >>>>>>  drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
> >>>>>>  3 files changed, 90 insertions(+)
> >>>>>>  create mode 100644 drivers/mfd/mtk-mmsys.c
> >>>>>>
> >>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> >>>>>> index b860eb5aa194..d23a3b9a2c58 100644
> >>>>>> --- a/drivers/mfd/Kconfig
> >>>>>> +++ b/drivers/mfd/Kconfig
> >>>>>> @@ -378,6 +378,15 @@ config MFD_MC13XXX_I2C
> >>>>>>  	help
> >>>>>>  	  Select this if your MC13xxx is connected via an I2C bus.
> >>>>>>  
> >>>>>> +config MFD_MEDIATEK_MMSYS
> >>>>>> +	tristate "Mediatek MMSYS interface"
> >>>>>> +	select MFD_CORE
> >>>>>> +	select REGMAP_MMIO
> >>>>>> +	help
> >>>>>> +	  Select this if you have a MMSYS subsystem in your SoC. The
> >>>>>> +	  MMSYS subsystem has at least a clock driver part and some
> >>>>>> +	  DRM components.
> >>>>>> +
> >>>>>>  config MFD_MXS_LRADC
> >>>>>>  	tristate "Freescale i.MX23/i.MX28 LRADC"
> >>>>>>  	depends on ARCH_MXS || COMPILE_TEST
> >>>>>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> >>>>>> index d9d2cf0d32ef..b96118bd68d9 100644
> >>>>>> --- a/drivers/mfd/Makefile
> >>>>>> +++ b/drivers/mfd/Makefile
> >>>>>> @@ -98,6 +98,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
> >>>>>>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
> >>>>>>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
> >>>>>>  
> >>>>>> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
> >>>>>> +
> >>>>>>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
> >>>>>>  
> >>>>>>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
> >>>>>> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
> >>>>>> new file mode 100644
> >>>>>> index 000000000000..c802343fb1c6
> >>>>>> --- /dev/null
> >>>>>> +++ b/drivers/mfd/mtk-mmsys.c
> >>>>>> @@ -0,0 +1,79 @@
> >>>>>> +// SPDX-License-Identifier: GPL-2.0+
> >>>>>> +
> >>>>>> +/*
> >>>>>> + * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
> >>>>>> + *
> >>>>>> + * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
> >>>>>> + *
> >>>>>> + * Author: Matthias Brugger <matthias.bgg@gmail.com>
> >>>>>> + */
> >>>>>> +
> >>>>>> +#include <linux/module.h>
> >>>>>> +#include <linux/init.h>
> >>>>>> +#include <linux/mfd/core.h>
> >>>>>> +#include <linux/of.h>
> >>>>>> +#include <linux/of_address.h>
> >>>>>> +#include <linux/of_device.h>
> >>>>>> +#include <linux/platform_device.h>
> >>>>>> +#include <linux/regmap.h>
> >>>>>> +
> >>>>>> +enum {
> >>>>>> +	MMSYS_MT2701 = 1,
> >>>>>> +};
> >>>>>> +
> >>>>>> +static const struct mfd_cell mmsys_mt2701_devs[] = {
> >>>>>> +	{ .name = "clk-mt2701-mm", },
> >>>>>> +	{ .name = "drm-mt2701-mm", },
> >>>>>> +};
> >>>>>> +
> >>>>>> +static int mmsys_probe(struct platform_device *pdev)
> >>>>>> +{
> >>>>>> +	const struct mfd_cell *mmsys_cells;
> >>>>>> +	int nr_cells;
> >>>>>> +	long id;
> >>>>>> +	int ret;
> >>>>>> +
> >>>>>> +	id = (long) of_device_get_match_data(&pdev->dev);
> >>>>>> +	if (!id) {
> >>>>>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
> >>>>>> +		return -EINVAL;
> >>>>>> +	}
> >>>>>> +
> >>>>>> +	switch (id) {
> >>>>>> +	case MMSYS_MT2701:
> >>>>>> +		mmsys_cells = mmsys_mt2701_devs;
> >>>>>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
> >>>>>> +		break;
> >>>>>> +	default:
> >>>>>> +		return -ENODEV;
> >>>>>> +	}
> >>>>>> +
> >>>>>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
> >>>>>> +					NULL, 0, NULL);
> >>>>>> +	if (ret) {
> >>>>>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
> >>>>>> +		return ret;
> >>>>>> +	}
> >>>>>> +
> >>>>>> +	return 0;
> >>>>>> +};
> >>>>>
> >>>>> This driver is pretty pointless.  It doesn't actually do anything.
> >>>>>
> >>>>> I think you just want to use "simple-mfd" instead.
> >>>>>
> >>>>
> >>>> I think the problem is, that right now we have two drivers which use the same
> >>>> devicetree binding, which are clk and drm driver. With a simple-mfd we would
> >>>> need two compatibles, and this would break backwards compatibility.
> >>>
> >>> So what functionality does this driver provide you with that you do
> >>> not have currently?
> >>>
> >>
> >> I'm not sure if I get your question. Point is, that the MMSYS implementation for
> >> mt8173 is broken, as it assumes that we can probe two drivers with the
> >> mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
> >> understand it was a bug. So older devicetrees use just on mt8173-mmsys
> >> compatible in ther DTB.
> > 
> > Okay, that is what I was getting at.  Thanks for the explanation.
> > 
> > Do you have a datasheet I can look at?
> > 
> 
> Unfortunately there is no datasheet you can get without a NDA. The only public
> available information I'm aware of is for the (not upstream supported) 96board
> [1]. And it's only the register description. You can find some more explanation
> about the MMSYS in older threads which tried to solve the very same problem [2]
> 
> [1]
> https://www.96boards.org/documentation/consumer/mediatekx20/additional-docs/docs/MT6797_Register_Table_Part_2.pdf
> [2] http://lists.infradead.org/pipermail/linux-mediatek/2017-October/010979.html

And now we have some history.  Thanks for providing those.

So my initial reaction is the one I have just confirmed for myself.
MFD is being used as a work-around in this odd use-case and really
isn't the right place for it.

If you're adamant that you do not wish to change the Device Tree, my
suggestion is to either move the clk functionality into the DRM
driver, or register the clk driver from DRM using standard
platform_device_register() API.

> >> I would like to keep backwards compatibility for the device tree, that's why I
> >> was searching for a solution where we can probe two drivers and came up with
> >> this mfd solution.
> >>
> >> So no new functionality, the clk driver provides the clock the drm components need.
> >
Matthias Brugger July 6, 2018, 1:18 p.m. UTC | #10
On 05/07/18 14:22, Lee Jones wrote:
> On Thu, 05 Jul 2018, Matthias Brugger wrote:
>> On 04/07/18 18:45, Lee Jones wrote:
>>> On Wed, 04 Jul 2018, Matthias Brugger wrote:
>>>> On 03/07/18 09:11, Lee Jones wrote:
>>>>> On Mon, 25 Jun 2018, Matthias Brugger wrote:
>>>>>> On 30/04/18 12:18, Lee Jones wrote:
>>>>>>> On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:
[...]
>>>>>>>> +static int mmsys_probe(struct platform_device *pdev)
>>>>>>>> +{
>>>>>>>> +	const struct mfd_cell *mmsys_cells;
>>>>>>>> +	int nr_cells;
>>>>>>>> +	long id;
>>>>>>>> +	int ret;
>>>>>>>> +
>>>>>>>> +	id = (long) of_device_get_match_data(&pdev->dev);
>>>>>>>> +	if (!id) {
>>>>>>>> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
>>>>>>>> +		return -EINVAL;
>>>>>>>> +	}
>>>>>>>> +
>>>>>>>> +	switch (id) {
>>>>>>>> +	case MMSYS_MT2701:
>>>>>>>> +		mmsys_cells = mmsys_mt2701_devs;
>>>>>>>> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
>>>>>>>> +		break;
>>>>>>>> +	default:
>>>>>>>> +		return -ENODEV;
>>>>>>>> +	}
>>>>>>>> +
>>>>>>>> +	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
>>>>>>>> +					NULL, 0, NULL);
>>>>>>>> +	if (ret) {
>>>>>>>> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
>>>>>>>> +		return ret;
>>>>>>>> +	}
>>>>>>>> +
>>>>>>>> +	return 0;
>>>>>>>> +};
>>>>>>>
>>>>>>> This driver is pretty pointless.  It doesn't actually do anything.
>>>>>>>
>>>>>>> I think you just want to use "simple-mfd" instead.
>>>>>>>
>>>>>>
>>>>>> I think the problem is, that right now we have two drivers which use the same
>>>>>> devicetree binding, which are clk and drm driver. With a simple-mfd we would
>>>>>> need two compatibles, and this would break backwards compatibility.
>>>>>
>>>>> So what functionality does this driver provide you with that you do
>>>>> not have currently?
>>>>>
>>>>
>>>> I'm not sure if I get your question. Point is, that the MMSYS implementation for
>>>> mt8173 is broken, as it assumes that we can probe two drivers with the
>>>> mediatek,mt8173-mmsys compatible. Somehow it used to work, but from what I
>>>> understand it was a bug. So older devicetrees use just on mt8173-mmsys
>>>> compatible in ther DTB.
>>>
>>> Okay, that is what I was getting at.  Thanks for the explanation.
>>>
>>> Do you have a datasheet I can look at?
>>>
>>
>> Unfortunately there is no datasheet you can get without a NDA. The only public
>> available information I'm aware of is for the (not upstream supported) 96board
>> [1]. And it's only the register description. You can find some more explanation
>> about the MMSYS in older threads which tried to solve the very same problem [2]
>>
>> [1]
>> https://www.96boards.org/documentation/consumer/mediatekx20/additional-docs/docs/MT6797_Register_Table_Part_2.pdf
>> [2] http://lists.infradead.org/pipermail/linux-mediatek/2017-October/010979.html
> 
> And now we have some history.  Thanks for providing those.
> 
> So my initial reaction is the one I have just confirmed for myself.
> MFD is being used as a work-around in this odd use-case and really
> isn't the right place for it.
> 
> If you're adamant that you do not wish to change the Device Tree, my
> suggestion is to either move the clk functionality into the DRM
> driver, or register the clk driver from DRM using standard
> platform_device_register() API.
> 

Ok, I'll try to come up with a solution with a platform device for the clocks.
Stay tuened. Thanks for your feedback!

Matthias

Patch
diff mbox

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b860eb5aa194..d23a3b9a2c58 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -378,6 +378,15 @@  config MFD_MC13XXX_I2C
 	help
 	  Select this if your MC13xxx is connected via an I2C bus.
 
+config MFD_MEDIATEK_MMSYS
+	tristate "Mediatek MMSYS interface"
+	select MFD_CORE
+	select REGMAP_MMIO
+	help
+	  Select this if you have a MMSYS subsystem in your SoC. The
+	  MMSYS subsystem has at least a clock driver part and some
+	  DRM components.
+
 config MFD_MXS_LRADC
 	tristate "Freescale i.MX23/i.MX28 LRADC"
 	depends on ARCH_MXS || COMPILE_TEST
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index d9d2cf0d32ef..b96118bd68d9 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -98,6 +98,8 @@  obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
 obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
 obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
+obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
+
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
 obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
new file mode 100644
index 000000000000..c802343fb1c6
--- /dev/null
+++ b/drivers/mfd/mtk-mmsys.c
@@ -0,0 +1,79 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * mtk-mmsys.c -- Mediatek MMSYS multi-function driver
+ *
+ * Copyright (c) 2018 Matthias Brugger <matthias.bgg@gmail.com>
+ *
+ * Author: Matthias Brugger <matthias.bgg@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/mfd/core.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+enum {
+	MMSYS_MT2701 = 1,
+};
+
+static const struct mfd_cell mmsys_mt2701_devs[] = {
+	{ .name = "clk-mt2701-mm", },
+	{ .name = "drm-mt2701-mm", },
+};
+
+static int mmsys_probe(struct platform_device *pdev)
+{
+	const struct mfd_cell *mmsys_cells;
+	int nr_cells;
+	long id;
+	int ret;
+
+	id = (long) of_device_get_match_data(&pdev->dev);
+	if (!id) {
+		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
+		return -EINVAL;
+	}
+
+	switch (id) {
+	case MMSYS_MT2701:
+		mmsys_cells = mmsys_mt2701_devs;
+		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	ret = devm_mfd_add_devices(&pdev->dev, 0, mmsys_cells, nr_cells,
+					NULL, 0, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+};
+
+static const struct of_device_id of_match_mmsys[] = {
+	{ .compatible = "mediatek,mt2701-mmsys",
+	  .data = (void *) MMSYS_MT2701,
+	},
+	{ /* sentinel */ },
+};
+
+static struct platform_driver mmsys_drv = {
+	.probe = mmsys_probe,
+	.driver = {
+		.name = "mediatek-mmysys",
+		.of_match_table = of_match_ptr(of_match_mmsys),
+	},
+};
+
+builtin_platform_driver(mmsys_drv);
+
+MODULE_DESCRIPTION("Mediatek MMSYS multi-function driver");
+MODULE_LICENSE("GPL");