On 2/8/20 4:35 PM, Jonathan Cameron wrote:
> On Wed, 5 Feb 2020 11:47:58 +0100
> Fabrice Gasnier <fabrice.gasnier@xxxxxx> 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@xxxxxx>
>> ---
>> 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);
>
