[PATCHv5,1/3] OMAP: I2C: Reset support
diff mbox

Message ID 1311935813-8481-2-git-send-email-shubhrajyoti@ti.com
State New, archived
Headers show

Commit Message

Shubhrajyoti Datta July 29, 2011, 10:36 a.m. UTC
Under some error conditions the i2c  driver may do a reset.
 Adding a reset field and support in the platform.

Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
---
 arch/arm/plat-omap/i2c.c |   18 ++++++++++++++++++
 include/linux/i2c-omap.h |    1 +
 2 files changed, 19 insertions(+), 0 deletions(-)

Comments

Kevin Hilman Aug. 2, 2011, 11:23 p.m. UTC | #1
Shubhrajyoti D <shubhrajyoti@ti.com> writes:

>  Under some error conditions the i2c  driver may do a reset.
  ^                                    ^
minor: extra whitespace

>  Adding a reset field and support in the platform.

s/platform/device-specific code/

> Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>

That being said, omap_device_shutdown() should already do a clean
shutdown + reset for you, and i2c-omap.h already has a pointer for
->device_shutdown() so a new device_reset() should not be needed.

IOW, simply adding pdata->device_shutdown = omap_device_shutdown()
should work.

Kevin

> ---
>  arch/arm/plat-omap/i2c.c |   18 ++++++++++++++++++
>  include/linux/i2c-omap.h |    1 +
>  2 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
> index 2388b8e..be36cac 100644
> --- a/arch/arm/plat-omap/i2c.c
> +++ b/arch/arm/plat-omap/i2c.c
> @@ -146,6 +146,22 @@ static struct omap_device_pm_latency omap_i2c_latency[] = {
>  		.flags			= OMAP_DEVICE_LATENCY_AUTO_ADJUST,
>  	},
>  };
> +/**
> + * omap2_i2c_reset - reset the omap i2c module.
> + * @dev: struct device*
> + */
> +
> +static int omap2_i2c_reset(struct device *dev)
> +{
> +	int r = 0;
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct omap_device *odev = to_omap_device(pdev);
> +	struct omap_hwmod *oh;
> +
> +	oh = odev->hwmods[0];
> +	r = omap_hwmod_reset(oh);
> +	return r;
> +}
>
>  static inline int omap2_i2c_add_bus(int bus_id)
>  {
> @@ -187,6 +203,8 @@ static inline int omap2_i2c_add_bus(int bus_id)
>  	 */
>  	if (cpu_is_omap34xx())
>  		pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
> +
> +	pdata->device_reset = omap2_i2c_reset;
>  	od = omap_device_build(name, bus_id, oh, pdata,
>  			sizeof(struct omap_i2c_bus_platform_data),
>  			omap_i2c_latency, ARRAY_SIZE(omap_i2c_latency), 0);
> diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
> index 98ae49b..8aa91b6 100644
> --- a/include/linux/i2c-omap.h
> +++ b/include/linux/i2c-omap.h
> @@ -38,6 +38,7 @@ struct omap_i2c_bus_platform_data {
>  	int		(*device_enable) (struct platform_device *pdev);
>  	int		(*device_shutdown) (struct platform_device *pdev);
>  	int		(*device_idle) (struct platform_device *pdev);
> +	int		(*device_reset) (struct device *dev);
>  };
>  
>  #endif
Shubhrajyoti Datta Aug. 4, 2011, 6:25 a.m. UTC | #2
On Wednesday 03 August 2011 04:53 AM, Kevin Hilman wrote:
> Shubhrajyoti D<shubhrajyoti@ti.com>  writes:
>
>>   Under some error conditions the i2c  driver may do a reset.
>    ^                                    ^
> minor: extra whitespace
>
>>   Adding a reset field and support in the platform.
> s/platform/device-specific code/
>
Yes will fix these.
>> Signed-off-by: Shubhrajyoti D<shubhrajyoti@ti.com>
> That being said, omap_device_shutdown() should already do a clean
> shutdown + reset for you, and i2c-omap.h already has a pointer for
> ->device_shutdown() so a new device_reset() should not be needed.
>
> IOW, simply adding pdata->device_shutdown = omap_device_shutdown()
> should work.
i2C has a special reset sequence ie Disable -> reset -> enable -> Poll 
on reset done.
This function is implemented in omap_i2c_reset. The

omap_hwmod_reset calls ->  _reset

which calls ocp_softrest  or custom reset if it is present.The latter is 
true for I2C.

However I see that

omap_device_shutdown ->  _assert_hardreset However for I2c there doesnt seem to be a HW reset line.


Am I missing something?

> Kevin
>
>> ---
>>   arch/arm/plat-omap/i2c.c |   18 ++++++++++++++++++
>>   include/linux/i2c-omap.h |    1 +
>>   2 files changed, 19 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
>> index 2388b8e..be36cac 100644
>> --- a/arch/arm/plat-omap/i2c.c
>> +++ b/arch/arm/plat-omap/i2c.c
>> @@ -146,6 +146,22 @@ static struct omap_device_pm_latency omap_i2c_latency[] = {
>>   		.flags			= OMAP_DEVICE_LATENCY_AUTO_ADJUST,
>>   	},
>>   };
>> +/**
>> + * omap2_i2c_reset - reset the omap i2c module.
>> + * @dev: struct device*
>> + */
>> +
>> +static int omap2_i2c_reset(struct device *dev)
>> +{
>> +	int r = 0;
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct omap_device *odev = to_omap_device(pdev);
>> +	struct omap_hwmod *oh;
>> +
>> +	oh = odev->hwmods[0];
>> +	r = omap_hwmod_reset(oh);
>> +	return r;
>> +}
>>
>>   static inline int omap2_i2c_add_bus(int bus_id)
>>   {
>> @@ -187,6 +203,8 @@ static inline int omap2_i2c_add_bus(int bus_id)
>>   	 */
>>   	if (cpu_is_omap34xx())
>>   		pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
>> +
>> +	pdata->device_reset = omap2_i2c_reset;
>>   	od = omap_device_build(name, bus_id, oh, pdata,
>>   			sizeof(struct omap_i2c_bus_platform_data),
>>   			omap_i2c_latency, ARRAY_SIZE(omap_i2c_latency), 0);
>> diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
>> index 98ae49b..8aa91b6 100644
>> --- a/include/linux/i2c-omap.h
>> +++ b/include/linux/i2c-omap.h
>> @@ -38,6 +38,7 @@ struct omap_i2c_bus_platform_data {
>>   	int		(*device_enable) (struct platform_device *pdev);
>>   	int		(*device_shutdown) (struct platform_device *pdev);
>>   	int		(*device_idle) (struct platform_device *pdev);
>> +	int		(*device_reset) (struct device *dev);
>>   };
>>
>>   #endif
Kevin Hilman Aug. 4, 2011, 3:05 p.m. UTC | #3
Shubhrajyoti <shubhrajyoti@ti.com> writes:

> On Wednesday 03 August 2011 04:53 AM, Kevin Hilman wrote:
>> Shubhrajyoti D<shubhrajyoti@ti.com>  writes:
>>
>>>   Under some error conditions the i2c  driver may do a reset.
>>    ^                                    ^
>> minor: extra whitespace
>>
>>>   Adding a reset field and support in the platform.
>> s/platform/device-specific code/
>>
> Yes will fix these.
>>> Signed-off-by: Shubhrajyoti D<shubhrajyoti@ti.com>
>> That being said, omap_device_shutdown() should already do a clean
>> shutdown + reset for you, and i2c-omap.h already has a pointer for
>> ->device_shutdown() so a new device_reset() should not be needed.
>>
>> IOW, simply adding pdata->device_shutdown = omap_device_shutdown()
>> should work.
> i2C has a special reset sequence ie Disable -> reset -> enable -> Poll
> on reset done.
> This function is implemented in omap_i2c_reset. The
>
> omap_hwmod_reset calls ->  _reset
>
> which calls ocp_softrest  or custom reset if it is present.The latter
> is true for I2C.
>
> However I see that
>
> omap_device_shutdown ->  _assert_hardreset However for I2c there doesnt seem to be a HW reset line.
>
>
> Am I missing something?
>

No, my fault.

I thought omap_device_shutdown() also did soft reset, but I see that's
not the case.  You can ignore my comments about using
omap_device_shutdown.

Kevin

Patch
diff mbox

diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index 2388b8e..be36cac 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -146,6 +146,22 @@  static struct omap_device_pm_latency omap_i2c_latency[] = {
 		.flags			= OMAP_DEVICE_LATENCY_AUTO_ADJUST,
 	},
 };
+/**
+ * omap2_i2c_reset - reset the omap i2c module.
+ * @dev: struct device*
+ */
+
+static int omap2_i2c_reset(struct device *dev)
+{
+	int r = 0;
+	struct platform_device *pdev = to_platform_device(dev);
+	struct omap_device *odev = to_omap_device(pdev);
+	struct omap_hwmod *oh;
+
+	oh = odev->hwmods[0];
+	r = omap_hwmod_reset(oh);
+	return r;
+}
 
 static inline int omap2_i2c_add_bus(int bus_id)
 {
@@ -187,6 +203,8 @@  static inline int omap2_i2c_add_bus(int bus_id)
 	 */
 	if (cpu_is_omap34xx())
 		pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
+
+	pdata->device_reset = omap2_i2c_reset;
 	od = omap_device_build(name, bus_id, oh, pdata,
 			sizeof(struct omap_i2c_bus_platform_data),
 			omap_i2c_latency, ARRAY_SIZE(omap_i2c_latency), 0);
diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
index 98ae49b..8aa91b6 100644
--- a/include/linux/i2c-omap.h
+++ b/include/linux/i2c-omap.h
@@ -38,6 +38,7 @@  struct omap_i2c_bus_platform_data {
 	int		(*device_enable) (struct platform_device *pdev);
 	int		(*device_shutdown) (struct platform_device *pdev);
 	int		(*device_idle) (struct platform_device *pdev);
+	int		(*device_reset) (struct device *dev);
 };
 
 #endif