[PATCH 2/2] iio:adc:at91-sama5d2: add support for differential conversions

[Jonathan Cameron]

On 22/03/16 16:08, Ludovic Desroches wrote:
> Add signed differential channels and update the voltage scale for
> differential conversions.
> 
> Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
Looks good to me.

Applied to the togreg branch of iio.git - initially pushed out as testing
etc etc.

Jonathan
> ---
> 
> This patch is based on:
> iio:adc:at91-sama5d2: fix identation
> iio:adc:at91-sama5d2: fix typo
> 
>  drivers/iio/adc/at91-sama5d2_adc.c | 71 ++++++++++++++++++++++++++++++--------
>  1 file changed, 56 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 01ba106..07adb10 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -113,8 +113,11 @@
>  #define AT91_SAMA5D2_CWR	0x44
>  /* Channel Gain Register */
>  #define AT91_SAMA5D2_CGR	0x48
> +
Ever so slight gripe here as this is unconnected to this patch so should have
been in a trivial additional patch... 
>  /* Channel Offset Register */
>  #define AT91_SAMA5D2_COR	0x4c
> +#define AT91_SAMA5D2_COR_DIFF_OFFSET	16
> +
>  /* Channel Data Register 0 */
>  #define AT91_SAMA5D2_CDR0	0x50
>  /* Analog Control Register */
> @@ -142,7 +145,7 @@
>  /* Version Register */
>  #define AT91_SAMA5D2_VERSION	0xfc
>  
> -#define AT91_SAMA5D2_CHAN(num, addr)					\
> +#define AT91_SAMA5D2_CHAN_SINGLE(num, addr)				\
>  	{								\
>  		.type = IIO_VOLTAGE,					\
>  		.channel = num,						\
> @@ -158,6 +161,24 @@
>  		.indexed = 1,						\
>  	}
>  
> +#define AT91_SAMA5D2_CHAN_DIFF(num, num2, addr)				\
> +	{								\
> +		.type = IIO_VOLTAGE,					\
> +		.differential = 1,					\
> +		.channel = num,						\
> +		.channel2 = num2,					\
> +		.address = addr,					\
> +		.scan_type = {						\
> +			.sign = 's',					\
> +			.realbits = 12,					\
> +		},							\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
> +		.datasheet_name = "CH"#num"-CH"#num2,			\
> +		.indexed = 1,						\
> +	}
> +
>  #define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
>  #define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)
>  
> @@ -187,18 +208,24 @@ struct at91_adc_state {
>  };
>  
>  static const struct iio_chan_spec at91_adc_channels[] = {
> -	AT91_SAMA5D2_CHAN(0, 0x50),
> -	AT91_SAMA5D2_CHAN(1, 0x54),
> -	AT91_SAMA5D2_CHAN(2, 0x58),
> -	AT91_SAMA5D2_CHAN(3, 0x5c),
> -	AT91_SAMA5D2_CHAN(4, 0x60),
> -	AT91_SAMA5D2_CHAN(5, 0x64),
> -	AT91_SAMA5D2_CHAN(6, 0x68),
> -	AT91_SAMA5D2_CHAN(7, 0x6c),
> -	AT91_SAMA5D2_CHAN(8, 0x70),
> -	AT91_SAMA5D2_CHAN(9, 0x74),
> -	AT91_SAMA5D2_CHAN(10, 0x78),
> -	AT91_SAMA5D2_CHAN(11, 0x7c),
> +	AT91_SAMA5D2_CHAN_SINGLE(0, 0x50),
> +	AT91_SAMA5D2_CHAN_SINGLE(1, 0x54),
> +	AT91_SAMA5D2_CHAN_SINGLE(2, 0x58),
> +	AT91_SAMA5D2_CHAN_SINGLE(3, 0x5c),
> +	AT91_SAMA5D2_CHAN_SINGLE(4, 0x60),
> +	AT91_SAMA5D2_CHAN_SINGLE(5, 0x64),
> +	AT91_SAMA5D2_CHAN_SINGLE(6, 0x68),
> +	AT91_SAMA5D2_CHAN_SINGLE(7, 0x6c),
> +	AT91_SAMA5D2_CHAN_SINGLE(8, 0x70),
> +	AT91_SAMA5D2_CHAN_SINGLE(9, 0x74),
> +	AT91_SAMA5D2_CHAN_SINGLE(10, 0x78),
> +	AT91_SAMA5D2_CHAN_SINGLE(11, 0x7c),
> +	AT91_SAMA5D2_CHAN_DIFF(0, 1, 0x50),
> +	AT91_SAMA5D2_CHAN_DIFF(2, 3, 0x58),
> +	AT91_SAMA5D2_CHAN_DIFF(4, 5, 0x60),
> +	AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
> +	AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
> +	AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
>  };
>  
>  static unsigned at91_adc_startup_time(unsigned startup_time_min,
> @@ -281,6 +308,7 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
>  			     int *val, int *val2, long mask)
>  {
>  	struct at91_adc_state *st = iio_priv(indio_dev);
> +	u32 cor = 0;
>  	int ret;
>  
>  	switch (mask) {
> @@ -289,6 +317,11 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
>  
>  		st->chan = chan;
>  
> +		if (chan->differential)
> +			cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
> +			      AT91_SAMA5D2_COR_DIFF_OFFSET;
> +
> +		at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
>  		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
>  		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
>  		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
> @@ -301,6 +334,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
>  
>  		if (ret > 0) {
>  			*val = st->conversion_value;
> +			if (chan->scan_type.sign == 's')
> +				*val = sign_extend32(*val, 11);
>  			ret = IIO_VAL_INT;
>  			st->conversion_done = false;
>  		}
> @@ -313,6 +348,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
>  
>  	case IIO_CHAN_INFO_SCALE:
>  		*val = st->vref_uv / 1000;
> +		if (chan->differential)
> +			*val *= 2;
>  		*val2 = chan->scan_type.realbits;
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  
> @@ -447,8 +484,12 @@ static int at91_adc_probe(struct platform_device *pdev)
>  
>  	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. */
> -	at91_adc_writel(st, AT91_SAMA5D2_MR, AT91_SAMA5D2_MR_TRANSFER(2));
> +	/*
> +	 * 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);
>  
>