Subject: Re: [PATCH 1/7] iio: adc: sun4i-gpadc: rework for support multiple thermal sensor

From: Jonathan Cameron <[email-masked]>
Date: Sun, 5 May 2019 16:22:15 +0100

On Fri,  3 May 2019 03:28:07 -0400
Yangtao Li <[email-masked]> wrote:

> For some SOCs, there are more than one thermal sensor, and there are
> currently four sensors on the A80. So we need to do some work in order
> to support multiple thermal sensors:
> 
>   1) add sensor_count in gpadc_data.
>   2) introduce sun4i_sensor_tzd in sun4i_gpadc_iio, to support multiple
>      thermal_zone_device and distinguish between different sensors.
>   3) modify read temperature and initialization function.
This comment doesn't mention the devm change. If it had it would have
raised immediate alarm bells.

I'm also not keen on the web of pointers that this driver is steadily
evolving.  I can't immediately see how to reduce that complexity however.

Jonathan

> 
> Signed-off-by: Yangtao Li <[email-masked]>
> ---
>  drivers/iio/adc/sun4i-gpadc-iio.c | 61 +++++++++++++++++++++++--------
>  1 file changed, 45 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index 04d7147e0110..844fd52bd22f 100644
> --- a/drivers/iio/adc/sun4i-gpadc-iio.c
> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
> @@ -56,6 +56,7 @@ struct gpadc_data {
>  	unsigned int	tp_adc_select;
>  	unsigned int	(*adc_chan_select)(unsigned int chan);
>  	unsigned int	adc_chan_mask;
> +	unsigned int    sensor_count;
>  };
>  
>  static const struct gpadc_data sun4i_gpadc_data = {
> @@ -65,6 +66,7 @@ static const struct gpadc_data sun4i_gpadc_data = {
>  	.tp_adc_select = SUN4I_GPADC_CTRL1_TP_ADC_SELECT,
>  	.adc_chan_select = &sun4i_gpadc_chan_select,
>  	.adc_chan_mask = SUN4I_GPADC_CTRL1_ADC_CHAN_MASK,
> +	.sensor_count = 1,
>  };
>  
>  static const struct gpadc_data sun5i_gpadc_data = {
> @@ -74,6 +76,7 @@ static const struct gpadc_data sun5i_gpadc_data = {
>  	.tp_adc_select = SUN4I_GPADC_CTRL1_TP_ADC_SELECT,
>  	.adc_chan_select = &sun4i_gpadc_chan_select,
>  	.adc_chan_mask = SUN4I_GPADC_CTRL1_ADC_CHAN_MASK,
> +	.sensor_count = 1,
>  };
>  
>  static const struct gpadc_data sun6i_gpadc_data = {
> @@ -83,14 +86,24 @@ static const struct gpadc_data sun6i_gpadc_data = {
>  	.tp_adc_select = SUN6I_GPADC_CTRL1_TP_ADC_SELECT,
>  	.adc_chan_select = &sun6i_gpadc_chan_select,
>  	.adc_chan_mask = SUN6I_GPADC_CTRL1_ADC_CHAN_MASK,
> +	.sensor_count = 1,
>  };
>  
>  static const struct gpadc_data sun8i_a33_gpadc_data = {
>  	.temp_offset = -1662,
>  	.temp_scale = 162,
>  	.tp_mode_en = SUN8I_GPADC_CTRL1_CHOP_TEMP_EN,
> +	.sensor_count = 1,
>  };
>  
> +struct sun4i_sensor_tzd {
> +	struct sun4i_gpadc_iio          *info;
> +	struct thermal_zone_device      *tzd;
> +	unsigned int                    sensor_id;
> +};
> +
> +#define MAX_SENSOR_COUNT	4
> +
>  struct sun4i_gpadc_iio {
>  	struct iio_dev			*indio_dev;
>  	struct completion		completion;
> @@ -105,7 +118,7 @@ struct sun4i_gpadc_iio {
>  	bool				no_irq;
>  	/* prevents concurrent reads of temperature and ADC */
>  	struct mutex			mutex;
> -	struct thermal_zone_device	*tzd;
> +	struct sun4i_sensor_tzd         tzds[MAX_SENSOR_COUNT];
>  	struct device			*sensor_device;
>  };
>  
> @@ -270,7 +283,8 @@ static int sun4i_gpadc_adc_read(struct iio_dev *indio_dev, int channel,
>  	return sun4i_gpadc_read(indio_dev, channel, val, info->fifo_data_irq);
>  }
>  
> -static int sun4i_gpadc_temp_read(struct iio_dev *indio_dev, int *val)
> +static int sun4i_gpadc_temp_read(struct iio_dev *indio_dev, int *val,
> +				 unsigned int sensor)
>  {
>  	struct sun4i_gpadc_iio *info = iio_priv(indio_dev);
>  
> @@ -324,7 +338,7 @@ static int sun4i_gpadc_read_raw(struct iio_dev *indio_dev,
>  			ret = sun4i_gpadc_adc_read(indio_dev, chan->channel,
>  						   val);
>  		else
> -			ret = sun4i_gpadc_temp_read(indio_dev, val);
> +			ret = sun4i_gpadc_temp_read(indio_dev, val, 0);
>  
>  		if (ret)
>  			return ret;
> @@ -417,10 +431,11 @@ static int sun4i_gpadc_runtime_resume(struct device *dev)
>  
>  static int sun4i_gpadc_get_temp(void *data, int *temp)
>  {
> -	struct sun4i_gpadc_iio *info = data;
> +	struct sun4i_sensor_tzd *tzd = data;
> +	struct sun4i_gpadc_iio *info = tzd->info;
>  	int val, scale, offset;
>  
> -	if (sun4i_gpadc_temp_read(info->indio_dev, &val))
> +	if (sun4i_gpadc_temp_read(info->indio_dev, &val, tzd->sensor_id))
>  		return -ETIMEDOUT;
>  
>  	sun4i_gpadc_temp_scale(info->indio_dev, &scale);
> @@ -609,6 +624,28 @@ static int sun4i_gpadc_probe_mfd(struct platform_device *pdev,
>  	return 0;
>  }
>  
> +static int sun4i_sensor_init(struct sun4i_gpadc_iio *info)
> +{
> +	int i = 0;
> +
> +	for (; i < info->data->sensor_count; i++) {
> +		info->tzds[i].info = info;
> +		info->tzds[i].sensor_id = i;
> +		info->tzds[i].tzd = devm_thermal_zone_of_sensor_register(
> +					info->sensor_device, i, &info->tzds[i],
> +					&sun4i_ts_tz_ops);

Using devm here has the result that the thermal_zones are remove 'after'
the end of the remove function for this driver.  That means you have
them still registered after several other commands are run in the remove
function.

Please ensure that the probe and remove orders are mirror images of each
other. Here it doesn't make a huge amount of actual difference but
it does make the code harder to reason about.

You 'could' propose a devm_ version of iio_map_array_register and
then use that to ensure the ordering is correctly maintained.

> +
> +		if (IS_ERR(info->tzds[i].tzd)) {
> +			dev_err(info->sensor_device,
> +				"could not register thermal sensor: %ld\n",
> +				PTR_ERR(info->tzds[i].tzd));
> +			return PTR_ERR(info->tzds[i].tzd);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int sun4i_gpadc_probe(struct platform_device *pdev)
>  {
>  	struct sun4i_gpadc_iio *info;
> @@ -646,19 +683,13 @@ static int sun4i_gpadc_probe(struct platform_device *pdev)
>  	pm_runtime_enable(&pdev->dev);
>  
>  	if (IS_ENABLED(CONFIG_THERMAL_OF)) {
> -		info->tzd = thermal_zone_of_sensor_register(info->sensor_device,
> -							    0, info,
> -							    &sun4i_ts_tz_ops);
> +		ret = sun4i_sensor_init(info);
>  		/*
>  		 * Do not fail driver probing when failing to register in
>  		 * thermal because no thermal DT node is found.
>  		 */
> -		if (IS_ERR(info->tzd) && PTR_ERR(info->tzd) != -ENODEV) {
> -			dev_err(&pdev->dev,
> -				"could not register thermal sensor: %ld\n",
> -				PTR_ERR(info->tzd));
> -			return PTR_ERR(info->tzd);
> -		}
> +		if (ret && ret != -ENODEV)
> +			return ret;
>  	}
>  
>  	ret = devm_iio_device_register(&pdev->dev, indio_dev);
> @@ -690,8 +721,6 @@ static int sun4i_gpadc_remove(struct platform_device *pdev)
>  	if (!IS_ENABLED(CONFIG_THERMAL_OF))
>  		return 0;
>  
> -	thermal_zone_of_sensor_unregister(info->sensor_device, info->tzd);
> -
>  	if (!info->no_irq)
>  		iio_map_array_unregister(indio_dev);
>  

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