[PATCH] counter: stm32-timer-cnt: add power management support

[PATCH] counter: stm32-timer-cnt: add power management support

[Fabrice Gasnier]

Add suspend/resume PM sleep ops. When going to low power, enforce the
counter isn't active.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/counter/stm32-timer-cnt.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
index 3eafcce..3b84503 100644
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -12,6 +12,7 @@
 #include <linux/iio/types.h>
 #include <linux/mfd/stm32-timers.h>
 #include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 
 #define TIM_CCMR_CCXS	(BIT(8) | BIT(0))
@@ -358,10 +359,33 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
 	priv->counter.num_signals = ARRAY_SIZE(stm32_signals);
 	priv->counter.priv = priv;
 
+	platform_set_drvdata(pdev, priv);
+
 	/* Register Counter device */
 	return devm_counter_register(dev, &priv->counter);
 }
 
+static int __maybe_unused stm32_timer_cnt_suspend(struct device *dev)
+{
+	struct stm32_timer_cnt *priv = dev_get_drvdata(dev);
+	u32 cr1;
+
+	/* Check for active counter */
+	regmap_read(priv->regmap, TIM_CR1, &cr1);
+	if (cr1 & TIM_CR1_CEN)
+		return -EBUSY;
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int __maybe_unused stm32_timer_cnt_resume(struct device *dev)
+{
+	return pinctrl_pm_select_default_state(dev);
+}
+
+static SIMPLE_DEV_PM_OPS(stm32_timer_cnt_pm_ops, stm32_timer_cnt_suspend,
+			 stm32_timer_cnt_resume);
+
 static const struct of_device_id stm32_timer_cnt_of_match[] = {
 	{ .compatible = "st,stm32-timer-counter", },
 	{},
@@ -373,6 +397,7 @@ static struct platform_driver stm32_timer_cnt_driver = {
 	.driver = {
 		.name = "stm32-timer-counter",
 		.of_match_table = stm32_timer_cnt_of_match,
+		.pm = &stm32_timer_cnt_pm_ops,
 	},
 };
 module_platform_driver(stm32_timer_cnt_driver);
-- 
2.7.4

Re: [PATCH] counter: stm32-timer-cnt: add power management support

[William Breathitt Gray]

On Wed, Feb 05, 2020 at 11:47:58AM +0100, Fabrice Gasnier wrote:
> Add suspend/resume PM sleep ops. When going to low power, enforce the
> counter isn't active.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>

These changes are purely for the PM ops and don't involve the Counter
API, so I don't see any see any issues with this patch from my end.

Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>

> ---
>  drivers/counter/stm32-timer-cnt.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
> index 3eafcce..3b84503 100644
> --- a/drivers/counter/stm32-timer-cnt.c
> +++ b/drivers/counter/stm32-timer-cnt.c
> @@ -12,6 +12,7 @@
>  #include <linux/iio/types.h>
>  #include <linux/mfd/stm32-timers.h>
>  #include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  
>  #define TIM_CCMR_CCXS	(BIT(8) | BIT(0))
> @@ -358,10 +359,33 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
>  	priv->counter.num_signals = ARRAY_SIZE(stm32_signals);
>  	priv->counter.priv = priv;
>  
> +	platform_set_drvdata(pdev, priv);
> +
>  	/* Register Counter device */
>  	return devm_counter_register(dev, &priv->counter);
>  }
>  
> +static int __maybe_unused stm32_timer_cnt_suspend(struct device *dev)
> +{
> +	struct stm32_timer_cnt *priv = dev_get_drvdata(dev);
> +	u32 cr1;
> +
> +	/* Check for active counter */
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (cr1 & TIM_CR1_CEN)
> +		return -EBUSY;
> +
> +	return pinctrl_pm_select_sleep_state(dev);
> +}
> +
> +static int __maybe_unused stm32_timer_cnt_resume(struct device *dev)
> +{
> +	return pinctrl_pm_select_default_state(dev);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(stm32_timer_cnt_pm_ops, stm32_timer_cnt_suspend,
> +			 stm32_timer_cnt_resume);
> +
>  static const struct of_device_id stm32_timer_cnt_of_match[] = {
>  	{ .compatible = "st,stm32-timer-counter", },
>  	{},
> @@ -373,6 +397,7 @@ static struct platform_driver stm32_timer_cnt_driver = {
>  	.driver = {
>  		.name = "stm32-timer-counter",
>  		.of_match_table = stm32_timer_cnt_of_match,
> +		.pm = &stm32_timer_cnt_pm_ops,
>  	},
>  };
>  module_platform_driver(stm32_timer_cnt_driver);
> -- 
> 2.7.4
> 

Re: [PATCH] counter: stm32-timer-cnt: add power management support

[Jonathan Cameron]

On Wed, 5 Feb 2020 11:47:58 +0100
Fabrice Gasnier <fabrice.gasnier@st.com> wrote:

> Add suspend/resume PM sleep ops. When going to low power, enforce the
> counter isn't active.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  drivers/counter/stm32-timer-cnt.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
> index 3eafcce..3b84503 100644
> --- a/drivers/counter/stm32-timer-cnt.c
> +++ b/drivers/counter/stm32-timer-cnt.c
> @@ -12,6 +12,7 @@
>  #include <linux/iio/types.h>
>  #include <linux/mfd/stm32-timers.h>
>  #include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  
>  #define TIM_CCMR_CCXS	(BIT(8) | BIT(0))
> @@ -358,10 +359,33 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
>  	priv->counter.num_signals = ARRAY_SIZE(stm32_signals);
>  	priv->counter.priv = priv;
>  
> +	platform_set_drvdata(pdev, priv);
> +
>  	/* Register Counter device */
>  	return devm_counter_register(dev, &priv->counter);
>  }
>  
> +static int __maybe_unused stm32_timer_cnt_suspend(struct device *dev)
> +{
> +	struct stm32_timer_cnt *priv = dev_get_drvdata(dev);
> +	u32 cr1;
> +
> +	/* Check for active counter */
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (cr1 & TIM_CR1_CEN)
> +		return -EBUSY;

Runtime suspend is allowed to refuse to happen (and that is
explicitly documented)
Is that allowed for normal suspend?  I didn't think it was.
This will stop a suspend, but it's doing it by signalling a failure.
I'm not sure for example that the system will resume everything that
was suspended before this call.

Normally you are in the tough luck category if a system decides
to suspend underneath you.   There are ways to prevent it
from userspace (wakelocks etc).

> +
> +	return pinctrl_pm_select_sleep_state(dev);
> +}
> +
> +static int __maybe_unused stm32_timer_cnt_resume(struct device *dev)
> +{
> +	return pinctrl_pm_select_default_state(dev);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(stm32_timer_cnt_pm_ops, stm32_timer_cnt_suspend,
> +			 stm32_timer_cnt_resume);
> +
>  static const struct of_device_id stm32_timer_cnt_of_match[] = {
>  	{ .compatible = "st,stm32-timer-counter", },
>  	{},
> @@ -373,6 +397,7 @@ static struct platform_driver stm32_timer_cnt_driver = {
>  	.driver = {
>  		.name = "stm32-timer-counter",
>  		.of_match_table = stm32_timer_cnt_of_match,
> +		.pm = &stm32_timer_cnt_pm_ops,
>  	},
>  };
>  module_platform_driver(stm32_timer_cnt_driver);

Re: [PATCH] counter: stm32-timer-cnt: add power management support

[Fabrice Gasnier]

On 2/8/20 4:35 PM, Jonathan Cameron wrote:
> On Wed, 5 Feb 2020 11:47:58 +0100
> Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
> 
>> Add suspend/resume PM sleep ops. When going to low power, enforce the
>> counter isn't active.
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>> ---
>>  drivers/counter/stm32-timer-cnt.c | 25 +++++++++++++++++++++++++
>>  1 file changed, 25 insertions(+)
>>
>> diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
>> index 3eafcce..3b84503 100644
>> --- a/drivers/counter/stm32-timer-cnt.c
>> +++ b/drivers/counter/stm32-timer-cnt.c
>> @@ -12,6 +12,7 @@
>>  #include <linux/iio/types.h>
>>  #include <linux/mfd/stm32-timers.h>
>>  #include <linux/module.h>
>> +#include <linux/pinctrl/consumer.h>
>>  #include <linux/platform_device.h>
>>  
>>  #define TIM_CCMR_CCXS	(BIT(8) | BIT(0))
>> @@ -358,10 +359,33 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
>>  	priv->counter.num_signals = ARRAY_SIZE(stm32_signals);
>>  	priv->counter.priv = priv;
>>  
>> +	platform_set_drvdata(pdev, priv);
>> +
>>  	/* Register Counter device */
>>  	return devm_counter_register(dev, &priv->counter);
>>  }
>>  
>> +static int __maybe_unused stm32_timer_cnt_suspend(struct device *dev)
>> +{
>> +	struct stm32_timer_cnt *priv = dev_get_drvdata(dev);
>> +	u32 cr1;
>> +
>> +	/* Check for active counter */
>> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +	if (cr1 & TIM_CR1_CEN)
>> +		return -EBUSY;
> 
> Runtime suspend is allowed to refuse to happen (and that is
> explicitly documented)
> Is that allowed for normal suspend?  I didn't think it was.
> This will stop a suspend, but it's doing it by signalling a failure.

Hi Jonathan,

I'll rework this patch, to avoid stopping the suspend. Another approach
is to properly save/backup the registers here, and to disable the
counter in low power mode.
I'll update this in V2.

Thanks for reviewing,
Fabrice

> I'm not sure for example that the system will resume everything that
> was suspended before this call.
> 
> Normally you are in the tough luck category if a system decides
> to suspend underneath you.   There are ways to prevent it
> from userspace (wakelocks etc).
> 
>> +
>> +	return pinctrl_pm_select_sleep_state(dev);
>> +}
>> +
>> +static int __maybe_unused stm32_timer_cnt_resume(struct device *dev)
>> +{
>> +	return pinctrl_pm_select_default_state(dev);
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(stm32_timer_cnt_pm_ops, stm32_timer_cnt_suspend,
>> +			 stm32_timer_cnt_resume);
>> +
>>  static const struct of_device_id stm32_timer_cnt_of_match[] = {
>>  	{ .compatible = "st,stm32-timer-counter", },
>>  	{},
>> @@ -373,6 +397,7 @@ static struct platform_driver stm32_timer_cnt_driver = {
>>  	.driver = {
>>  		.name = "stm32-timer-counter",
>>  		.of_match_table = stm32_timer_cnt_of_match,
>> +		.pm = &stm32_timer_cnt_pm_ops,
>>  	},
>>  };
>>  module_platform_driver(stm32_timer_cnt_driver);
>