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SubjectRe: [PATCH 2/2] iio: trigger: stm32-timer: add power management support
On Tue, 3 Mar 2020 15:59:45 +0100
Fabrice Gasnier <fabrice.gasnier@st.com> wrote:

> Add suspend/resume PM sleep ops to stm32-timer-trigger driver.
> Register contents may be lost depending on low power modes.
> When going to low power, enforce the timer isn't active. Gracefully
> restore its state upon resume in case it's been left enabled prior to
> suspend.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Seems sensible. Applied,

Thanks,

Jonathan

> ---
> drivers/iio/trigger/stm32-timer-trigger.c | 63 +++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
>
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index 32e1249..37545a8 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -75,6 +75,15 @@ static const void *stm32h7_valids_table[][MAX_VALIDS] = {
> { }, /* timer 17 */
> };
>
> +struct stm32_timer_trigger_regs {
> + u32 cr1;
> + u32 cr2;
> + u32 psc;
> + u32 arr;
> + u32 cnt;
> + u32 smcr;
> +};
> +
> struct stm32_timer_trigger {
> struct device *dev;
> struct regmap *regmap;
> @@ -86,6 +95,7 @@ struct stm32_timer_trigger {
> bool has_trgo2;
> struct mutex lock; /* concurrent sysfs configuration */
> struct list_head tr_list;
> + struct stm32_timer_trigger_regs bak;
> };
>
> struct stm32_timer_trigger_cfg {
> @@ -812,6 +822,58 @@ static int stm32_timer_trigger_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static int __maybe_unused stm32_timer_trigger_suspend(struct device *dev)
> +{
> + struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
> +
> + /* Only take care of enabled timer: don't disturb other MFD child */
> + if (priv->enabled) {
> + /* Backup registers that may get lost in low power mode */
> + regmap_read(priv->regmap, TIM_CR1, &priv->bak.cr1);
> + regmap_read(priv->regmap, TIM_CR2, &priv->bak.cr2);
> + regmap_read(priv->regmap, TIM_PSC, &priv->bak.psc);
> + regmap_read(priv->regmap, TIM_ARR, &priv->bak.arr);
> + regmap_read(priv->regmap, TIM_CNT, &priv->bak.cnt);
> + regmap_read(priv->regmap, TIM_SMCR, &priv->bak.smcr);
> +
> + /* Disable the timer */
> + regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
> + clk_disable(priv->clk);
> + }
> +
> + return 0;
> +}
> +
> +static int __maybe_unused stm32_timer_trigger_resume(struct device *dev)
> +{
> + struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
> + int ret;
> +
> + if (priv->enabled) {
> + ret = clk_enable(priv->clk);
> + if (ret)
> + return ret;
> +
> + /* restore master/slave modes */
> + regmap_write(priv->regmap, TIM_SMCR, priv->bak.smcr);
> + regmap_write(priv->regmap, TIM_CR2, priv->bak.cr2);
> +
> + /* restore sampling_frequency (trgo / trgo2 triggers) */
> + regmap_write(priv->regmap, TIM_PSC, priv->bak.psc);
> + regmap_write(priv->regmap, TIM_ARR, priv->bak.arr);
> + regmap_write(priv->regmap, TIM_CNT, priv->bak.cnt);
> +
> + /* Also re-enables the timer */
> + regmap_write(priv->regmap, TIM_CR1, priv->bak.cr1);
> + }
> +
> + return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(stm32_timer_trigger_pm_ops,
> + stm32_timer_trigger_suspend,
> + stm32_timer_trigger_resume);
> +
> static const struct stm32_timer_trigger_cfg stm32_timer_trg_cfg = {
> .valids_table = valids_table,
> .num_valids_table = ARRAY_SIZE(valids_table),
> @@ -840,6 +902,7 @@ static struct platform_driver stm32_timer_trigger_driver = {
> .driver = {
> .name = "stm32-timer-trigger",
> .of_match_table = stm32_trig_of_match,
> + .pm = &stm32_timer_trigger_pm_ops,
> },
> };
> module_platform_driver(stm32_timer_trigger_driver);

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