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.gasn...@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(+) 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
