[v2,3/3] pwm: stm32: add power management support
diff mbox series

Message ID 1570193633-6600-4-git-send-email-fabrice.gasnier@st.com
State New
Headers show
Series
  • Add PM support to STM32 Timer PWM
Related show

Commit Message

Fabrice Gasnier Oct. 4, 2019, 12:53 p.m. UTC
Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
channel isn't active. Let the PWM consumers disable it during their own
suspend sequence, see [1]. So, perform a check here, and handle the
pinctrl states. Also restore the break inputs upon resume, as registers
content may be lost when going to low power mode.

[1] https://lkml.org/lkml/2019/2/5/770

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
Changes in v2:
Follow Uwe suggestions/remarks:
- Add a precursor patch to ease reviewing
- Use registers read instead of pwm_get_state
- Add a comment to mention registers content may be lost in low power mode
---
 drivers/pwm/pwm-stm32.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

Comments

Thierry Reding Oct. 16, 2019, 7:06 a.m. UTC | #1
On Fri, Oct 04, 2019 at 02:53:53PM +0200, Fabrice Gasnier wrote:
> Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
> channel isn't active. Let the PWM consumers disable it during their own
> suspend sequence, see [1]. So, perform a check here, and handle the
> pinctrl states. Also restore the break inputs upon resume, as registers
> content may be lost when going to low power mode.
> 
> [1] https://lkml.org/lkml/2019/2/5/770
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
> Changes in v2:
> Follow Uwe suggestions/remarks:
> - Add a precursor patch to ease reviewing
> - Use registers read instead of pwm_get_state
> - Add a comment to mention registers content may be lost in low power mode
> ---
>  drivers/pwm/pwm-stm32.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)

Applied, thanks. I made two minor changes, though, see below.

> 
> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
> index cf8658c..546b661 100644
> --- a/drivers/pwm/pwm-stm32.c
> +++ b/drivers/pwm/pwm-stm32.c
> @@ -12,6 +12,7 @@
>  #include <linux/mfd/stm32-timers.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pwm.h>
>  
> @@ -655,6 +656,42 @@ static int stm32_pwm_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static int __maybe_unused stm32_pwm_suspend(struct device *dev)
> +{
> +	struct stm32_pwm *priv = dev_get_drvdata(dev);
> +	unsigned int ch;

I renamed this to just "i", which is more idiomatic for loop variables.
The function is small enough not to need to differentiate between loop
variables.

> +	u32 ccer, mask;
> +
> +	/* Look for active channels */
> +	ccer = active_channels(priv);
> +
> +	for (ch = 0; ch < priv->chip.npwm; ch++) {
> +		mask = TIM_CCER_CC1E << (ch * 4);
> +		if (ccer & mask) {
> +			dev_err(dev, "The consumer didn't stop us (%s)\n",
> +				priv->chip.pwms[ch].label);

Changed this to:

	"PWM %u still in use by consumer %s\n", i, priv->chip.pwms[i].label

I think that might help clarify which PWM is still enabled in case the
consumers don't set a label.

Thierry

> +			return -EBUSY;
> +		}
> +	}
> +
> +	return pinctrl_pm_select_sleep_state(dev);
> +}
> +
> +static int __maybe_unused stm32_pwm_resume(struct device *dev)
> +{
> +	struct stm32_pwm *priv = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = pinctrl_pm_select_default_state(dev);
> +	if (ret)
> +		return ret;
> +
> +	/* restore breakinput registers that may have been lost in low power */
> +	return stm32_pwm_apply_breakinputs(priv);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(stm32_pwm_pm_ops, stm32_pwm_suspend, stm32_pwm_resume);
> +
>  static const struct of_device_id stm32_pwm_of_match[] = {
>  	{ .compatible = "st,stm32-pwm",	},
>  	{ /* end node */ },
> @@ -667,6 +704,7 @@ static struct platform_driver stm32_pwm_driver = {
>  	.driver	= {
>  		.name = "stm32-pwm",
>  		.of_match_table = stm32_pwm_of_match,
> +		.pm = &stm32_pwm_pm_ops,
>  	},
>  };
>  module_platform_driver(stm32_pwm_driver);
> -- 
> 2.7.4
>
Fabrice Gasnier Oct. 16, 2019, 10:08 a.m. UTC | #2
On 10/16/19 9:06 AM, Thierry Reding wrote:
> On Fri, Oct 04, 2019 at 02:53:53PM +0200, Fabrice Gasnier wrote:
>> Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
>> channel isn't active. Let the PWM consumers disable it during their own
>> suspend sequence, see [1]. So, perform a check here, and handle the
>> pinctrl states. Also restore the break inputs upon resume, as registers
>> content may be lost when going to low power mode.
>>
>> [1] https://lkml.org/lkml/2019/2/5/770
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>> ---
>> Changes in v2:
>> Follow Uwe suggestions/remarks:
>> - Add a precursor patch to ease reviewing
>> - Use registers read instead of pwm_get_state
>> - Add a comment to mention registers content may be lost in low power mode
>> ---
>>  drivers/pwm/pwm-stm32.c | 38 ++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 38 insertions(+)
> 
> Applied, thanks. I made two minor changes, though, see below.
> 
>>
>> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
>> index cf8658c..546b661 100644
>> --- a/drivers/pwm/pwm-stm32.c
>> +++ b/drivers/pwm/pwm-stm32.c
>> @@ -12,6 +12,7 @@
>>  #include <linux/mfd/stm32-timers.h>
>>  #include <linux/module.h>
>>  #include <linux/of.h>
>> +#include <linux/pinctrl/consumer.h>
>>  #include <linux/platform_device.h>
>>  #include <linux/pwm.h>
>>  
>> @@ -655,6 +656,42 @@ static int stm32_pwm_remove(struct platform_device *pdev)
>>  	return 0;
>>  }
>>  
>> +static int __maybe_unused stm32_pwm_suspend(struct device *dev)
>> +{
>> +	struct stm32_pwm *priv = dev_get_drvdata(dev);
>> +	unsigned int ch;
> 
> I renamed this to just "i", which is more idiomatic for loop variables.
> The function is small enough not to need to differentiate between loop
> variables.
> 
>> +	u32 ccer, mask;
>> +
>> +	/* Look for active channels */
>> +	ccer = active_channels(priv);
>> +
>> +	for (ch = 0; ch < priv->chip.npwm; ch++) {
>> +		mask = TIM_CCER_CC1E << (ch * 4);
>> +		if (ccer & mask) {
>> +			dev_err(dev, "The consumer didn't stop us (%s)\n",
>> +				priv->chip.pwms[ch].label);
> 
> Changed this to:
> 
> 	"PWM %u still in use by consumer %s\n", i, priv->chip.pwms[i].label
> 
> I think that might help clarify which PWM is still enabled in case the
> consumers don't set a label.

Hi Thierry,

Many thanks for all the improvements on this series!

Best Regards,
Fabrice

> 
> Thierry
> 
>> +			return -EBUSY;
>> +		}
>> +	}
>> +
>> +	return pinctrl_pm_select_sleep_state(dev);
>> +}
>> +
>> +static int __maybe_unused stm32_pwm_resume(struct device *dev)
>> +{
>> +	struct stm32_pwm *priv = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = pinctrl_pm_select_default_state(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* restore breakinput registers that may have been lost in low power */
>> +	return stm32_pwm_apply_breakinputs(priv);
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(stm32_pwm_pm_ops, stm32_pwm_suspend, stm32_pwm_resume);
>> +
>>  static const struct of_device_id stm32_pwm_of_match[] = {
>>  	{ .compatible = "st,stm32-pwm",	},
>>  	{ /* end node */ },
>> @@ -667,6 +704,7 @@ static struct platform_driver stm32_pwm_driver = {
>>  	.driver	= {
>>  		.name = "stm32-pwm",
>>  		.of_match_table = stm32_pwm_of_match,
>> +		.pm = &stm32_pwm_pm_ops,
>>  	},
>>  };
>>  module_platform_driver(stm32_pwm_driver);
>> -- 
>> 2.7.4
>>

Patch
diff mbox series

diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index cf8658c..546b661 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -12,6 +12,7 @@ 
 #include <linux/mfd/stm32-timers.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 
@@ -655,6 +656,42 @@  static int stm32_pwm_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused stm32_pwm_suspend(struct device *dev)
+{
+	struct stm32_pwm *priv = dev_get_drvdata(dev);
+	unsigned int ch;
+	u32 ccer, mask;
+
+	/* Look for active channels */
+	ccer = active_channels(priv);
+
+	for (ch = 0; ch < priv->chip.npwm; ch++) {
+		mask = TIM_CCER_CC1E << (ch * 4);
+		if (ccer & mask) {
+			dev_err(dev, "The consumer didn't stop us (%s)\n",
+				priv->chip.pwms[ch].label);
+			return -EBUSY;
+		}
+	}
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int __maybe_unused stm32_pwm_resume(struct device *dev)
+{
+	struct stm32_pwm *priv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pinctrl_pm_select_default_state(dev);
+	if (ret)
+		return ret;
+
+	/* restore breakinput registers that may have been lost in low power */
+	return stm32_pwm_apply_breakinputs(priv);
+}
+
+static SIMPLE_DEV_PM_OPS(stm32_pwm_pm_ops, stm32_pwm_suspend, stm32_pwm_resume);
+
 static const struct of_device_id stm32_pwm_of_match[] = {
 	{ .compatible = "st,stm32-pwm",	},
 	{ /* end node */ },
@@ -667,6 +704,7 @@  static struct platform_driver stm32_pwm_driver = {
 	.driver	= {
 		.name = "stm32-pwm",
 		.of_match_table = stm32_pwm_of_match,
+		.pm = &stm32_pwm_pm_ops,
 	},
 };
 module_platform_driver(stm32_pwm_driver);