[PATCH v4] iio: adc: rockchip_saradc: add voltage notifier so get referenced voltage once at probe

[Jonathan Cameron]

On Tue, 10 Aug 2021 09:10:07 +0800
Simon Xue <xxm at rock-chips.com> wrote:

> From: David Wu <david.wu at rock-chips.com>
> 
> Add voltage notifier, no need to query regulator voltage for
> every saradc read, just get regulator voltage once at probe.
> 
> Signed-off-by: David Wu <david.wu at rock-chips.com>
> Signed-off-by: Simon Xue <xxm at rock-chips.com>
> Reviewed-by: Heiko Stuebner <heiko at sntech.de>
> ---

For future reference, there should be a changelog here under the ---
Sometimes it saves reviewers going back to check what they asked about
on earlier versions.
Otherwise looks good to me.

Applied to the togreg branch of iio.git and pushed out as testing for 0-day
to see if it can find any problems before I go breaking linux-next.

Thanks,

Jonathan

>  drivers/iio/adc/rockchip_saradc.c | 47 ++++++++++++++++++++++++++-----
>  1 file changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> index f3eb8d2e50dc..a237fe469a30 100644
> --- a/drivers/iio/adc/rockchip_saradc.c
> +++ b/drivers/iio/adc/rockchip_saradc.c
> @@ -49,10 +49,12 @@ struct rockchip_saradc {
>  	struct clk		*clk;
>  	struct completion	completion;
>  	struct regulator	*vref;
> +	int			uv_vref;
>  	struct reset_control	*reset;
>  	const struct rockchip_saradc_data *data;
>  	u16			last_val;
>  	const struct iio_chan_spec *last_chan;
> +	struct notifier_block nb;
>  };
>  
>  static void rockchip_saradc_power_down(struct rockchip_saradc *info)
> @@ -105,13 +107,7 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
>  		mutex_unlock(&indio_dev->mlock);
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SCALE:
> -		ret = regulator_get_voltage(info->vref);
> -		if (ret < 0) {
> -			dev_err(&indio_dev->dev, "failed to get voltage\n");
> -			return ret;
> -		}
> -
> -		*val = ret / 1000;
> +		*val = info->uv_vref / 1000;
>  		*val2 = chan->scan_type.realbits;
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  	default:
> @@ -298,6 +294,26 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p)
>  	return IRQ_HANDLED;
>  }
>  
> +static int rockchip_saradc_volt_notify(struct notifier_block *nb,
> +						   unsigned long event,
> +						   void *data)
> +{
> +	struct rockchip_saradc *info =
> +			container_of(nb, struct rockchip_saradc, nb);
> +
> +	if (event & REGULATOR_EVENT_VOLTAGE_CHANGE)
> +		info->uv_vref = (unsigned long)data;
> +
> +	return NOTIFY_OK;
> +}
> +
> +static void rockchip_saradc_regulator_unreg_notifier(void *data)
> +{
> +	struct rockchip_saradc *info = data;
> +
> +	regulator_unregister_notifier(info->vref, &info->nb);
> +}
> +
>  static int rockchip_saradc_probe(struct platform_device *pdev)
>  {
>  	struct rockchip_saradc *info = NULL;
> @@ -410,6 +426,12 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	ret = regulator_get_voltage(info->vref);
> +	if (ret < 0)
> +		return ret;
> +
> +	info->uv_vref = ret;
> +
>  	ret = clk_prepare_enable(info->pclk);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "failed to enable pclk\n");
> @@ -450,6 +472,17 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	info->nb.notifier_call = rockchip_saradc_volt_notify;
> +	ret = regulator_register_notifier(info->vref, &info->nb);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(&pdev->dev,
> +				       rockchip_saradc_regulator_unreg_notifier,
> +				       info);
> +	if (ret)
> +		return ret;
> +
>  	return devm_iio_device_register(&pdev->dev, indio_dev);
>  }
>