Re: [PATCH v1 07/10] iio:adc:at91-sama5d2: Support backup mode

[Nicolas Ferre <nicolas.ferre@microchip.com>]

On 08/09/2017 at 17:36, Romain Izard wrote:
> Support the backup mode for platform suspend, by restoring the hardware
> registers on resume.
> 
> Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>

Romain,

Thanks for your series: definitively some of your patches need to be
integrated (I've merged some of them in our current linux-4.9-at91 branch.
However, It seems that some of your additions have already been
submitted and/or accepted by maintainers.
For instance an equivalent of this one seems already in Linus' tree:
500a2eefd6b16ba141a8fb777ea6962d2eb65e3b ("iio: adc: at91-sama5d2_adc:
add support for suspend/resume functionality").

Please tell us if it fits what your observed on this driver (or others).

Regards,

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 71 ++++++++++++++++++++++++++++++++------
>  1 file changed, 61 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index e10dca3ed74b..f9718c863363 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -200,6 +200,7 @@ struct at91_adc_state {
>  	u32				conversion_value;
>  	struct at91_adc_soc_info	soc_info;
>  	wait_queue_head_t		wq_data_available;
> +	unsigned int			current_rate;
>  	/*
>  	 * lock to prevent concurrent 'single conversion' requests through
>  	 * sysfs.
> @@ -269,6 +270,8 @@ static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
>  	mr |= AT91_SAMA5D2_MR_PRESCAL(prescal);
>  	at91_adc_writel(st, AT91_SAMA5D2_MR, mr);
>  
> +	st->current_rate = freq;
> +
>  	dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
>  		freq, startup, prescal);
>  }
> @@ -375,7 +378,9 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
>  	    val > st->soc_info.max_sample_rate)
>  		return -EINVAL;
>  
> +	mutex_lock(&st->lock);
>  	at91_adc_setup_samp_freq(st, val);
> +	mutex_unlock(&st->lock);
>  
>  	return 0;
>  }
> @@ -386,6 +391,21 @@ static const struct iio_info at91_adc_info = {
>  	.driver_module = THIS_MODULE,
>  };
>  
> +static void at91_adc_init_hw(struct at91_adc_state *st, unsigned int freq)
> +{
> +	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
> +	at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
> +	/*
> +	 * Transfer field must be set to 2 according to the datasheet and
> +	 * allows different analog settings for each channel.
> +	 */
> +	at91_adc_writel(st, AT91_SAMA5D2_MR,
> +			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
> +
> +	at91_adc_setup_samp_freq(st, freq);
> +
> +}
> +
>  static int at91_adc_probe(struct platform_device *pdev)
>  {
>  	struct iio_dev *indio_dev;
> @@ -482,16 +502,7 @@ static int at91_adc_probe(struct platform_device *pdev)
>  		goto vref_disable;
>  	}
>  
> -	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
> -	at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
> -	/*
> -	 * Transfer field must be set to 2 according to the datasheet and
> -	 * allows different analog settings for each channel.
> -	 */
> -	at91_adc_writel(st, AT91_SAMA5D2_MR,
> -			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
> -
> -	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
> +	at91_adc_init_hw(st, st->soc_info.min_sample_rate);
>  
>  	ret = clk_prepare_enable(st->per_clk);
>  	if (ret)
> @@ -541,12 +552,52 @@ static const struct of_device_id at91_adc_dt_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, at91_adc_dt_match);
>  
> +#ifdef CONFIG_PM_SLEEP
> +static int at91_adc_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct at91_adc_state *st = iio_priv(indio_dev);
> +
> +	clk_disable_unprepare(st->per_clk);
> +
> +	regulator_disable(st->vref);
> +	regulator_disable(st->reg);
> +
> +	return 0;
> +}
> +
> +static int at91_adc_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct at91_adc_state *st = iio_priv(indio_dev);
> +	int err;
> +
> +	err = regulator_enable(st->reg);
> +	if (err)
> +		return err;
> +
> +	err = regulator_enable(st->vref);
> +	if (err)
> +		return err;
> +
> +	at91_adc_init_hw(st, st->current_rate);
> +
> +	err = clk_prepare_enable(st->per_clk);
> +	return err;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(at91_adc_pm_ops, at91_adc_suspend, at91_adc_resume);
> +
>  static struct platform_driver at91_adc_driver = {
>  	.probe = at91_adc_probe,
>  	.remove = at91_adc_remove,
>  	.driver = {
>  		.name = "at91-sama5d2_adc",
>  		.of_match_table = at91_adc_dt_match,
> +		.pm = &at91_adc_pm_ops,
>  	},
>  };
>  module_platform_driver(at91_adc_driver)
> 


-- 
Nicolas Ferre