Re: [PATCH 2/2] iio: adc: meson-saradc: use the address attribute from iio_chan_spec

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 25 Sep 2018 00:13:26 +0200
Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:

> Until now the "channel" number is identical to how the channel is
> identified inside the (FIFO) registers. In our case we have eight
> channels and the hardware also has eight inputs.
> 
> However, there are two special inputs:
> - channel 6 can select between the SAR_ADC_CH6 pad and the chip's
>   internal temperature sensor
> - channel 7 can select between SAR_ADC_CH7 and VSS, VDD / 4, VDD / 2,
>   VDD * 3 / 4 and VDD.
> 
> When programming the registers to read for example the temperature
> sensor we have to select FIFO channel 6, set the correct bit which muxes
> channel 6 to the temperature sensor and then start the ADC measurement
> for channel 6 as usual.
> 
> When we add support for the temperature sensor the driver has to know
> about that it has to use FIFO channel 6 to measure using the chip's
> internal temperature sensor. However, in that case the iio_chan_spec
> channel will not be 6 because this is already used for the SAR_ADC_CH6
> pad input. Thus we use iio_chan_spec's address field to store the FIFO
> channel number for each channel.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Again, clearly 'correct' so applied to the togreg branch of iio.git
and pushed out as testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/meson_saradc.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index 809d1230be34..028ccd218f82 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -172,6 +172,7 @@
>  	.type = IIO_VOLTAGE,						\
>  	.indexed = 1,							\
>  	.channel = _chan,						\
> +	.address = _chan,						\
>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
>  				BIT(IIO_CHAN_INFO_AVERAGE_RAW),		\
>  	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		\
> @@ -323,10 +324,10 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
>  
>  	regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
>  	fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval);
> -	if (fifo_chan != chan->channel) {
> +	if (fifo_chan != chan->address) {
>  		dev_err(&indio_dev->dev,
> -			"ADC FIFO entry belongs to channel %d instead of %d\n",
> -			fifo_chan, chan->channel);
> +			"ADC FIFO entry belongs to channel %d instead of %lu\n",
> +			fifo_chan, chan->address);
>  		return -EINVAL;
>  	}
>  
> @@ -343,16 +344,16 @@ static void meson_sar_adc_set_averaging(struct iio_dev *indio_dev,
>  					enum meson_sar_adc_num_samples samples)
>  {
>  	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> -	int val, channel = chan->channel;
> +	int val, address = chan->address;
>  
> -	val = samples << MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_SHIFT(channel);
> +	val = samples << MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_SHIFT(address);
>  	regmap_update_bits(priv->regmap, MESON_SAR_ADC_AVG_CNTL,
> -			   MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_MASK(channel),
> +			   MESON_SAR_ADC_AVG_CNTL_NUM_SAMPLES_MASK(address),
>  			   val);
>  
> -	val = mode << MESON_SAR_ADC_AVG_CNTL_AVG_MODE_SHIFT(channel);
> +	val = mode << MESON_SAR_ADC_AVG_CNTL_AVG_MODE_SHIFT(address);
>  	regmap_update_bits(priv->regmap, MESON_SAR_ADC_AVG_CNTL,
> -			   MESON_SAR_ADC_AVG_CNTL_AVG_MODE_MASK(channel), val);
> +			   MESON_SAR_ADC_AVG_CNTL_AVG_MODE_MASK(address), val);
>  }
>  
>  static void meson_sar_adc_enable_channel(struct iio_dev *indio_dev,
> @@ -372,23 +373,23 @@ static void meson_sar_adc_enable_channel(struct iio_dev *indio_dev,
>  
>  	/* map channel index 0 to the channel which we want to read */
>  	regval = FIELD_PREP(MESON_SAR_ADC_CHAN_LIST_ENTRY_MASK(0),
> -			    chan->channel);
> +			    chan->address);
>  	regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_LIST,
>  			   MESON_SAR_ADC_CHAN_LIST_ENTRY_MASK(0), regval);
>  
>  	regval = FIELD_PREP(MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MUX_MASK,
> -			    chan->channel);
> +			    chan->address);
>  	regmap_update_bits(priv->regmap, MESON_SAR_ADC_DETECT_IDLE_SW,
>  			   MESON_SAR_ADC_DETECT_IDLE_SW_DETECT_MUX_MASK,
>  			   regval);
>  
>  	regval = FIELD_PREP(MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK,
> -			    chan->channel);
> +			    chan->address);
>  	regmap_update_bits(priv->regmap, MESON_SAR_ADC_DETECT_IDLE_SW,
>  			   MESON_SAR_ADC_DETECT_IDLE_SW_IDLE_MUX_SEL_MASK,
>  			   regval);
>  
> -	if (chan->channel == 6)
> +	if (chan->address == 6)
>  		regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELTA_10,
>  				   MESON_SAR_ADC_DELTA_10_TEMP_SEL, 0);
>  }
> @@ -526,8 +527,8 @@ static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
>  
>  	if (ret) {
>  		dev_warn(indio_dev->dev.parent,
> -			 "failed to read sample for channel %d: %d\n",
> -			 chan->channel, ret);
> +			 "failed to read sample for channel %lu: %d\n",
> +			 chan->address, ret);
>  		return ret;
>  	}
>