This patch series adds power management support for STM32 Timer PWM:
- Document the pinctrl sleep state for STM32 Timer PWM
- STM32 Timer PWM driver
---
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
Fabrice Gasnier (3):
dt-bindings: pwm-stm32: document pinctrl sleep state
pwm: stm32: split breakinput apply routine to ease PM support
pwm: stm32: add power management support
.../devicetree/bindings/pwm/pwm-stm32.txt | 8 +-
drivers/pwm/pwm-stm32.c | 86 +++++++++++++++++-----
2 files changed, 71 insertions(+), 23 deletions(-)
--
2.7.4
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 <[email protected]>
---
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(+)
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);
--
2.7.4
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 <[email protected]>
> ---
> 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
>
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 <[email protected]>
>> ---
>> 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
>>