[PATCH v2] i2c-designware: Add suport for AMD i2c controller

[PATCH v2] i2c-designware: Add suport for AMD i2c controller

[Carl Peng]

AMD i2c bus controller is ACPI device, its ACPI ID
is "AMD0010". This patch is used to add support for
AMD i2c bus controller in the Designware platfrom
driver.

Signed-off-by: Carl Peng <carlpeng008-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-platdrv.c | 35 +++++++++++++++++++++++------
 2 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index d66b6cb..7a0a56e 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -105,6 +105,7 @@ struct dw_i2c_dev {
 	u16			ss_lcnt;
 	u16			fs_hcnt;
 	u16			fs_lcnt;
+	u32			vendor;
 };
 
 #define ACCESS_SWAP		0x00000001
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index bc87733..f0556c4 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -43,16 +43,26 @@
 #include <linux/acpi.h>
 #include "i2c-designware-core.h"
 
+#define AMD_CLK_KHZ		(133 * 1000)
+#define AMD_I2C_ACPI_ID		"AMD0010"
+#define VENDOR_ID_AMD		0x1022
+
 static struct i2c_algorithm i2c_dw_algo = {
 	.master_xfer	= i2c_dw_xfer,
 	.functionality	= i2c_dw_func,
 };
+
 static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev)
 {
 	return clk_get_rate(dev->clk)/1000;
 }
 
 #ifdef CONFIG_ACPI
+static u32 i2c_amd_get_clk_rate_khz(struct dw_i2c_dev *dev)
+{
+	return AMD_CLK_KHZ;
+}
+
 static void dw_i2c_acpi_params(struct platform_device *pdev, char method[],
 			       u16 *hcnt, u16 *lcnt, u32 *sda_hold)
 {
@@ -107,6 +117,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
 	{ "INT3433", 0 },
 	{ "80860F41", 0 },
 	{ "808622C1", 0 },
+	{ AMD_I2C_ACPI_ID, 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);
@@ -134,6 +145,9 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	if (!dev)
 		return -ENOMEM;
 
+	if (!strncmp(AMD_I2C_ACPI_ID, pdev->name, strlen(AMD_I2C_ACPI_ID)))
+		dev->vendor = VENDOR_ID_AMD;
+
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	dev->base = devm_ioremap_resource(&pdev->dev, mem);
 	if (IS_ERR(dev->base))
@@ -145,12 +159,15 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	dev->irq = irq;
 	platform_set_drvdata(pdev, dev);
 
-	dev->clk = devm_clk_get(&pdev->dev, NULL);
-	dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
+	if (dev->vendor != VENDOR_ID_AMD) {
+		dev->clk = devm_clk_get(&pdev->dev, NULL);
+		dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
 
-	if (IS_ERR(dev->clk))
-		return PTR_ERR(dev->clk);
-	clk_prepare_enable(dev->clk);
+		if (IS_ERR(dev->clk))
+			return PTR_ERR(dev->clk);
+		clk_prepare_enable(dev->clk);
+	} else
+		dev->get_clk_rate_khz = i2c_amd_get_clk_rate_khz;
 
 	if (pdev->dev.of_node) {
 		u32 ht = 0;
@@ -255,7 +272,9 @@ static int dw_i2c_suspend(struct device *dev)
 	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
 
 	i2c_dw_disable(i_dev);
-	clk_disable_unprepare(i_dev->clk);
+
+	if (i_dev->vendor != VENDOR_ID_AMD)
+		clk_disable_unprepare(i_dev->clk);
 
 	return 0;
 }
@@ -265,7 +284,9 @@ static int dw_i2c_resume(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
 
-	clk_prepare_enable(i_dev->clk);
+	if (i_dev->vendor != VENDOR_ID_AMD)
+		clk_prepare_enable(i_dev->clk);
+
 	i2c_dw_init(i_dev);
 
 	return 0;
-- 
1.9.1

Re: [PATCH v2] i2c-designware: Add suport for AMD i2c controller

[Mika Westerberg]

On Thu, Sep 04, 2014 at 08:30:05PM +0800, Carl Peng wrote:
> AMD i2c bus controller is ACPI device, its ACPI ID
> is "AMD0010". This patch is used to add support for
> AMD i2c bus controller in the Designware platfrom
> driver.
> 
> Signed-off-by: Carl Peng <carlpeng008-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-designware-core.h    |  1 +
>  drivers/i2c/busses/i2c-designware-platdrv.c | 35 +++++++++++++++++++++++------
>  2 files changed, 29 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index d66b6cb..7a0a56e 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -105,6 +105,7 @@ struct dw_i2c_dev {
>  	u16			ss_lcnt;
>  	u16			fs_hcnt;
>  	u16			fs_lcnt;
> +	u32			vendor;

Not needed.

>  };
>  
>  #define ACCESS_SWAP		0x00000001
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index bc87733..f0556c4 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -43,16 +43,26 @@
>  #include <linux/acpi.h>
>  #include "i2c-designware-core.h"
>  
> +#define AMD_CLK_KHZ		(133 * 1000)
> +#define AMD_I2C_ACPI_ID		"AMD0010"
> +#define VENDOR_ID_AMD		0x1022
> +
>  static struct i2c_algorithm i2c_dw_algo = {
>  	.master_xfer	= i2c_dw_xfer,
>  	.functionality	= i2c_dw_func,
>  };
> +

Unrelated change.

>  static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev)
>  {
>  	return clk_get_rate(dev->clk)/1000;
>  }
>  
>  #ifdef CONFIG_ACPI
> +static u32 i2c_amd_get_clk_rate_khz(struct dw_i2c_dev *dev)
> +{
> +	return AMD_CLK_KHZ;
> +}

No, use clock framework to pass correct clock rate to the driver.

> +
>  static void dw_i2c_acpi_params(struct platform_device *pdev, char method[],
>  			       u16 *hcnt, u16 *lcnt, u32 *sda_hold)
>  {
> @@ -107,6 +117,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
>  	{ "INT3433", 0 },
>  	{ "80860F41", 0 },
>  	{ "808622C1", 0 },
> +	{ AMD_I2C_ACPI_ID, 0 },

Please use "AMD0010" here.

>  	{ }
>  };
>  MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);
> @@ -134,6 +145,9 @@ static int dw_i2c_probe(struct platform_device *pdev)
>  	if (!dev)
>  		return -ENOMEM;
>  
> +	if (!strncmp(AMD_I2C_ACPI_ID, pdev->name, strlen(AMD_I2C_ACPI_ID)))
> +		dev->vendor = VENDOR_ID_AMD;
> +

This and rest of the hunks can be then dropped once you pass clocks
using clock framework. See how we do it for Intel LPSS devices in
drivers/acpi/acpi_lpss.c

>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	dev->base = devm_ioremap_resource(&pdev->dev, mem);
>  	if (IS_ERR(dev->base))
> @@ -145,12 +159,15 @@ static int dw_i2c_probe(struct platform_device *pdev)
>  	dev->irq = irq;
>  	platform_set_drvdata(pdev, dev);
>  
> -	dev->clk = devm_clk_get(&pdev->dev, NULL);
> -	dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
> +	if (dev->vendor != VENDOR_ID_AMD) {
> +		dev->clk = devm_clk_get(&pdev->dev, NULL);
> +		dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
>  
> -	if (IS_ERR(dev->clk))
> -		return PTR_ERR(dev->clk);
> -	clk_prepare_enable(dev->clk);
> +		if (IS_ERR(dev->clk))
> +			return PTR_ERR(dev->clk);
> +		clk_prepare_enable(dev->clk);
> +	} else
> +		dev->get_clk_rate_khz = i2c_amd_get_clk_rate_khz;
>  
>  	if (pdev->dev.of_node) {
>  		u32 ht = 0;
> @@ -255,7 +272,9 @@ static int dw_i2c_suspend(struct device *dev)
>  	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
>  
>  	i2c_dw_disable(i_dev);
> -	clk_disable_unprepare(i_dev->clk);
> +
> +	if (i_dev->vendor != VENDOR_ID_AMD)
> +		clk_disable_unprepare(i_dev->clk);
>  
>  	return 0;
>  }
> @@ -265,7 +284,9 @@ static int dw_i2c_resume(struct device *dev)
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
>  
> -	clk_prepare_enable(i_dev->clk);
> +	if (i_dev->vendor != VENDOR_ID_AMD)
> +		clk_prepare_enable(i_dev->clk);
> +
>  	i2c_dw_init(i_dev);
>  
>  	return 0;
> -- 
> 1.9.1

Re: [PATCH v2] i2c-designware: Add suport for AMD i2c controller

[carl peng]

Hi Mika,

Could I consult a problem with you?

As you suggest, there are some samples that add the device clk to the
clock framework in the acpi_lpss.c. But I encounter some problems when
add the AMD i2c clk to the clock framework.
In acpi_lpss.c, as the patch d6ddaaac8f5c37ad84d said, When the
CONFIG_X86_INTEL_LPSS is not defined, then only add the device ID
list, but not implement the callbacks like "attach =
acpi_lpss_create_device" , so if
CONFIG_X86_INTEL_LPSS is not defined, will not create clk dev.

So there will be some problems when I add the AMD i2c clk to the clock
framework.
if I do not define CONFIG_X86_INTEL_LPSS, then even though I add the IDs and
lpss_device_desc struct into the acpi_lpss.c, the AMD i2c clk will
also can not  be added into the clock framework. But if I add the AMD
i2c related IDs and struct in the CONFIG_X86_INTEL_LPSS, it may cause
some misunderstand in the future, it is a AMD device, why is it put
into the CONFIG_X86_INTEL_LPSS branch.

So, Could you please give some suggestions to me?
Which should I choose?
Add the AMD i2c clk IDs and related lpss_device_desc into the
CONFIG_X86_INTEL_LPSS branch, or re-write a new branch by imitating
the
CONFIG_X86_INTEL_LPSS branch  included by CONFIG_AMD_INTEL_LPSS.

Thank you,
Carl

On Thu, Sep 4, 2014 at 8:50 PM, Mika Westerberg
<mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:
> On Thu, Sep 04, 2014 at 08:30:05PM +0800, Carl Peng wrote:
>> AMD i2c bus controller is ACPI device, its ACPI ID
>> is "AMD0010". This patch is used to add support for
>> AMD i2c bus controller in the Designware platfrom
>> driver.
>>
>> Signed-off-by: Carl Peng <carlpeng008-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  drivers/i2c/busses/i2c-designware-core.h    |  1 +
>>  drivers/i2c/busses/i2c-designware-platdrv.c | 35 +++++++++++++++++++++++------
>>  2 files changed, 29 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
>> index d66b6cb..7a0a56e 100644
>> --- a/drivers/i2c/busses/i2c-designware-core.h
>> +++ b/drivers/i2c/busses/i2c-designware-core.h
>> @@ -105,6 +105,7 @@ struct dw_i2c_dev {
>>       u16                     ss_lcnt;
>>       u16                     fs_hcnt;
>>       u16                     fs_lcnt;
>> +     u32                     vendor;
>
> Not needed.
>
>>  };
>>
>>  #define ACCESS_SWAP          0x00000001
>> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
>> index bc87733..f0556c4 100644
>> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
>> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
>> @@ -43,16 +43,26 @@
>>  #include <linux/acpi.h>
>>  #include "i2c-designware-core.h"
>>
>> +#define AMD_CLK_KHZ          (133 * 1000)
>> +#define AMD_I2C_ACPI_ID              "AMD0010"
>> +#define VENDOR_ID_AMD                0x1022
>> +
>>  static struct i2c_algorithm i2c_dw_algo = {
>>       .master_xfer    = i2c_dw_xfer,
>>       .functionality  = i2c_dw_func,
>>  };
>> +
>
> Unrelated change.
>
>>  static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev)
>>  {
>>       return clk_get_rate(dev->clk)/1000;
>>  }
>>
>>  #ifdef CONFIG_ACPI
>> +static u32 i2c_amd_get_clk_rate_khz(struct dw_i2c_dev *dev)
>> +{
>> +     return AMD_CLK_KHZ;
>> +}
>
> No, use clock framework to pass correct clock rate to the driver.
>
>> +
>>  static void dw_i2c_acpi_params(struct platform_device *pdev, char method[],
>>                              u16 *hcnt, u16 *lcnt, u32 *sda_hold)
>>  {
>> @@ -107,6 +117,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
>>       { "INT3433", 0 },
>>       { "80860F41", 0 },
>>       { "808622C1", 0 },
>> +     { AMD_I2C_ACPI_ID, 0 },
>
> Please use "AMD0010" here.
>
>>       { }
>>  };
>>  MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);
>> @@ -134,6 +145,9 @@ static int dw_i2c_probe(struct platform_device *pdev)
>>       if (!dev)
>>               return -ENOMEM;
>>
>> +     if (!strncmp(AMD_I2C_ACPI_ID, pdev->name, strlen(AMD_I2C_ACPI_ID)))
>> +             dev->vendor = VENDOR_ID_AMD;
>> +
>
> This and rest of the hunks can be then dropped once you pass clocks
> using clock framework. See how we do it for Intel LPSS devices in
> drivers/acpi/acpi_lpss.c
>
>>       mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>       dev->base = devm_ioremap_resource(&pdev->dev, mem);
>>       if (IS_ERR(dev->base))
>> @@ -145,12 +159,15 @@ static int dw_i2c_probe(struct platform_device *pdev)
>>       dev->irq = irq;
>>       platform_set_drvdata(pdev, dev);
>>
>> -     dev->clk = devm_clk_get(&pdev->dev, NULL);
>> -     dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
>> +     if (dev->vendor != VENDOR_ID_AMD) {
>> +             dev->clk = devm_clk_get(&pdev->dev, NULL);
>> +             dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
>>
>> -     if (IS_ERR(dev->clk))
>> -             return PTR_ERR(dev->clk);
>> -     clk_prepare_enable(dev->clk);
>> +             if (IS_ERR(dev->clk))
>> +                     return PTR_ERR(dev->clk);
>> +             clk_prepare_enable(dev->clk);
>> +     } else
>> +             dev->get_clk_rate_khz = i2c_amd_get_clk_rate_khz;
>>
>>       if (pdev->dev.of_node) {
>>               u32 ht = 0;
>> @@ -255,7 +272,9 @@ static int dw_i2c_suspend(struct device *dev)
>>       struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
>>
>>       i2c_dw_disable(i_dev);
>> -     clk_disable_unprepare(i_dev->clk);
>> +
>> +     if (i_dev->vendor != VENDOR_ID_AMD)
>> +             clk_disable_unprepare(i_dev->clk);
>>
>>       return 0;
>>  }
>> @@ -265,7 +284,9 @@ static int dw_i2c_resume(struct device *dev)
>>       struct platform_device *pdev = to_platform_device(dev);
>>       struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
>>
>> -     clk_prepare_enable(i_dev->clk);
>> +     if (i_dev->vendor != VENDOR_ID_AMD)
>> +             clk_prepare_enable(i_dev->clk);
>> +
>>       i2c_dw_init(i_dev);
>>
>>       return 0;
>> --
>> 1.9.1

Re: [PATCH v2] i2c-designware: Add suport for AMD i2c controller

[Mika Westerberg]

On Fri, Sep 05, 2014 at 03:19:50PM +0800, carl peng wrote:
> Hi Mika,
> 
> Could I consult a problem with you?

Sure.

> 
> As you suggest, there are some samples that add the device clk to the
> clock framework in the acpi_lpss.c. But I encounter some problems when
> add the AMD i2c clk to the clock framework.
> In acpi_lpss.c, as the patch d6ddaaac8f5c37ad84d said, When the
> CONFIG_X86_INTEL_LPSS is not defined, then only add the device ID
> list, but not implement the callbacks like "attach =
> acpi_lpss_create_device" , so if
> CONFIG_X86_INTEL_LPSS is not defined, will not create clk dev.
> 
> So there will be some problems when I add the AMD i2c clk to the clock
> framework.
> if I do not define CONFIG_X86_INTEL_LPSS, then even though I add the IDs and
> lpss_device_desc struct into the acpi_lpss.c, the AMD i2c clk will
> also can not  be added into the clock framework. But if I add the AMD
> i2c related IDs and struct in the CONFIG_X86_INTEL_LPSS, it may cause
> some misunderstand in the future, it is a AMD device, why is it put
> into the CONFIG_X86_INTEL_LPSS branch.
> 
> So, Could you please give some suggestions to me?
> Which should I choose?
> Add the AMD i2c clk IDs and related lpss_device_desc into the
> CONFIG_X86_INTEL_LPSS branch, or re-write a new branch by imitating
> the
> CONFIG_X86_INTEL_LPSS branch  included by CONFIG_AMD_INTEL_LPSS.

Since the AMD part is probably too different from Intel LPSS devices, I
would rather not add it there. So you have two options AFAICT:

 1) Add the clock in drivers/acpi/acpi_platform.c
 2) Create custom i2c_get_clk_rate_khz() in the driver, just like in
    this patch but drop all the unnecessary vendor etc. dance.

For the 2) you could pass the clock rate in ->driver_data and if it is
non-zero, setup a custom clock rate function that then uses the value
from ->driver_data or so.

Not sure if Wolfram likes that but we don't have too many places in x86
world where we can create clocks :-(

Re: [PATCH v2] i2c-designware: Add suport for AMD i2c controller

[carl peng]

Hi Mika,

Excuse me, Could I consult one more question with you?
Could I add the AMD i2c controller private data like clk rate in the
platform_driver-->id_table but not in the
platform_driver-->acpi_match_table? The cause is as follow:


As you suggestion, I try to pass the clock rate in the ->driver_data,
so I add a line in the
dw_i2c_acpi_match[] array (drivers/i2c/busses/i2c-designware-platdrv.c):

       static const struct acpi_device_id dw_i2c_acpi_match[] = {
                      ...
                      { "AMD0010", (unsigned long)&amd_i2c_config}
                      ...
       }
       define the clock rate as a member of the amd_i2c_config structure.

But I find that I can not pass the clock rate by this way, since when
platform device match with with platform driver,
The driver_data of platform_driver-->acpi_match_table will not be
assigned to pdev->id_entry,
just the driver_data of platform_driver-->id_table will be assigned to
pdev->id_entry, as you know, AMD i2c controller
is a ACPI device, should use platform_driver-->acpi_match_table not
platform_driver-->id_table.

platform_match(drivers/base/platform.c)
|
acpi_driver_match_device(dev, drv)
|
return !!acpi_match_device(drv->acpi_match_table, dev);
|
return __acpi_match_device(adev, ids)(drivers/acpi/scan.c)
|
return id
Just return id, but will not assign id to pdev->id_entry.

Really expect your suggestion!
Thanks a lot!

Carl

On Fri, Sep 5, 2014 at 5:36 PM, Mika Westerberg
<mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:
> On Fri, Sep 05, 2014 at 03:19:50PM +0800, carl peng wrote:
>> Hi Mika,
>>
>> Could I consult a problem with you?
>
> Sure.
>
>>
>> As you suggest, there are some samples that add the device clk to the
>> clock framework in the acpi_lpss.c. But I encounter some problems when
>> add the AMD i2c clk to the clock framework.
>> In acpi_lpss.c, as the patch d6ddaaac8f5c37ad84d said, When the
>> CONFIG_X86_INTEL_LPSS is not defined, then only add the device ID
>> list, but not implement the callbacks like "attach =
>> acpi_lpss_create_device" , so if
>> CONFIG_X86_INTEL_LPSS is not defined, will not create clk dev.
>>
>> So there will be some problems when I add the AMD i2c clk to the clock
>> framework.
>> if I do not define CONFIG_X86_INTEL_LPSS, then even though I add the IDs and
>> lpss_device_desc struct into the acpi_lpss.c, the AMD i2c clk will
>> also can not  be added into the clock framework. But if I add the AMD
>> i2c related IDs and struct in the CONFIG_X86_INTEL_LPSS, it may cause
>> some misunderstand in the future, it is a AMD device, why is it put
>> into the CONFIG_X86_INTEL_LPSS branch.
>>
>> So, Could you please give some suggestions to me?
>> Which should I choose?
>> Add the AMD i2c clk IDs and related lpss_device_desc into the
>> CONFIG_X86_INTEL_LPSS branch, or re-write a new branch by imitating
>> the
>> CONFIG_X86_INTEL_LPSS branch  included by CONFIG_AMD_INTEL_LPSS.
>
> Since the AMD part is probably too different from Intel LPSS devices, I
> would rather not add it there. So you have two options AFAICT:
>
>  1) Add the clock in drivers/acpi/acpi_platform.c
>  2) Create custom i2c_get_clk_rate_khz() in the driver, just like in
>     this patch but drop all the unnecessary vendor etc. dance.
>
> For the 2) you could pass the clock rate in ->driver_data and if it is
> non-zero, setup a custom clock rate function that then uses the value
> from ->driver_data or so.
>
> Not sure if Wolfram likes that but we don't have too many places in x86
> world where we can create clocks :-(

Re: [PATCH v2] i2c-designware: Add suport for AMD i2c controller

[Mika Westerberg]

On Mon, Sep 15, 2014 at 07:58:29PM +0800, carl peng wrote:
> Hi Mika,
> 
> Excuse me, Could I consult one more question with you?

Sure.

> Could I add the AMD i2c controller private data like clk rate in the
> platform_driver-->id_table but not in the
> platform_driver-->acpi_match_table? The cause is as follow:
> 
> 
> As you suggestion, I try to pass the clock rate in the ->driver_data,
> so I add a line in the
> dw_i2c_acpi_match[] array (drivers/i2c/busses/i2c-designware-platdrv.c):
> 
>        static const struct acpi_device_id dw_i2c_acpi_match[] = {
>                       ...
>                       { "AMD0010", (unsigned long)&amd_i2c_config}
>                       ...
>        }
>        define the clock rate as a member of the amd_i2c_config structure.
> 
> But I find that I can not pass the clock rate by this way, since when
> platform device match with with platform driver,
> The driver_data of platform_driver-->acpi_match_table will not be
> assigned to pdev->id_entry,
> just the driver_data of platform_driver-->id_table will be assigned to
> pdev->id_entry, as you know, AMD i2c controller
> is a ACPI device, should use platform_driver-->acpi_match_table not
> platform_driver-->id_table.
> 
> platform_match(drivers/base/platform.c)
> |
> acpi_driver_match_device(dev, drv)
> |
> return !!acpi_match_device(drv->acpi_match_table, dev);
> |
> return __acpi_match_device(adev, ids)(drivers/acpi/scan.c)
> |
> return id
> Just return id, but will not assign id to pdev->id_entry.

You can call acpi_match_device(dw_i2c_acpi_match, &pdev->dev) in the
driver and look up the id->driver_data from the returned pointer.