Subject: Re: [PATCH 4/4] iio: counter: stm32-lptimer: Add power management support

From: Jonathan Cameron <[email-masked]>
Date: Sat, 9 Feb 2019 16:21:33 +0000

On Tue, 5 Feb 2019 13:40:29 +0100
Fabrice Gasnier <[email-masked]> wrote:

> Add suspend/resume PM sleep ops. When going to low power, disable
> active counter. Only active counter should be resumed: don't touch
> disabled counter, as it may be used by other LPTimer MFD child driver.
> 
> Signed-off-by: Fabrice Gasnier <[email-masked]>
I think this looks fine.  I'm not totally sure if patches 3,4 are
separable from 1,2 though so please let me know whether I should take
these now, or let all 4 go in together via some path?

Thanks,

Jonathan

> ---
>  drivers/iio/counter/stm32-lptimer-cnt.c | 55 +++++++++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/drivers/iio/counter/stm32-lptimer-cnt.c b/drivers/iio/counter/stm32-lptimer-cnt.c
> index 42fb8ba..2a49cce 100644
> --- a/drivers/iio/counter/stm32-lptimer-cnt.c
> +++ b/drivers/iio/counter/stm32-lptimer-cnt.c
> @@ -14,6 +14,7 @@
>  #include <linux/iio/iio.h>
>  #include <linux/mfd/stm32-lptimer.h>
>  #include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  
>  struct stm32_lptim_cnt {
> @@ -23,6 +24,7 @@ struct stm32_lptim_cnt {
>  	u32 preset;
>  	u32 polarity;
>  	u32 quadrature_mode;
> +	bool enabled;
>  };
>  
>  static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
> @@ -50,6 +52,7 @@ static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
>  
>  	if (!enable) {
>  		clk_disable(priv->clk);
> +		priv->enabled = false;
>  		return 0;
>  	}
>  
> @@ -79,6 +82,7 @@ static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
>  		regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
>  		return ret;
>  	}
> +	priv->enabled = true;
>  
>  	/* Start LP timer in continuous mode */
>  	return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
> @@ -361,6 +365,56 @@ static int stm32_lptim_cnt_probe(struct platform_device *pdev)
>  	return devm_iio_device_register(&pdev->dev, indio_dev);
>  }
>  
> +#ifdef CONFIG_PM_SLEEP
> +static int stm32_lptim_cnt_suspend(struct device *dev)
> +{
> +	struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
> +	int ret;
> +
> +	/* Only take care of enabled counter: don't disturb other MFD child */
> +	if (priv->enabled) {
> +		ret = stm32_lptim_setup(priv, 0);
> +		if (ret)
> +			return ret;
> +
> +		ret = stm32_lptim_set_enable_state(priv, 0);
> +		if (ret)
> +			return ret;
> +
> +		/* Force enable state for later resume */
> +		priv->enabled = true;
> +	}
> +
> +	return pinctrl_pm_select_sleep_state(dev);
> +}
> +
> +static int stm32_lptim_cnt_resume(struct device *dev)
> +{
> +	struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = pinctrl_pm_select_default_state(dev);
> +	if (ret)
> +		return ret;
> +
> +	if (priv->enabled) {
> +		priv->enabled = false;
> +		ret = stm32_lptim_setup(priv, 1);
> +		if (ret)
> +			return ret;
> +
> +		ret = stm32_lptim_set_enable_state(priv, 1);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(stm32_lptim_cnt_pm_ops, stm32_lptim_cnt_suspend,
> +			 stm32_lptim_cnt_resume);
> +
>  static const struct of_device_id stm32_lptim_cnt_of_match[] = {
>  	{ .compatible = "st,stm32-lptimer-counter", },
>  	{},
> @@ -372,6 +426,7 @@ static int stm32_lptim_cnt_probe(struct platform_device *pdev)
>  	.driver = {
>  		.name = "stm32-lptimer-counter",
>  		.of_match_table = stm32_lptim_cnt_of_match,
> +		.pm = &stm32_lptim_cnt_pm_ops,
>  	},
>  };
>  module_platform_driver(stm32_lptim_cnt_driver);

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