Re: [PATCH 4/4] iio: ad7476: Add support for the ad7091r

[Jonathan Cameron <jic23@kernel.org>]

On 09/17/2012 01:26 PM, Lars-Peter Clausen wrote:
> Add support for the ad7091r 12 bit ADC to the ad7476 driver. Although the
> ad7091r is not really related to any of the other devices supported by this
> driver, luckily for us there are not so many ways (which are not totally insane)
> how sampling a single channel ADC via SPI can be implemented and support for the
> ad7091r can be added to the driver with just a few adjustments.
Yup, eveything is nice and simple when there is only one channel ;)
> 
> The ad7091r requires an external "conversion start" pulse to start a sample
> conversion. After the conversion has finished the result can be read via SPI. We
> depend on a IIO trigger to generate this signal, as a result only sampling in
> buffered mode and not in manual mode is available.
This is a little restrictive given we could wire up some magic with a gpio to
do this, but I guess things like that can be added as and when people care.
We may need some way of 'knowing' whether a more general trigger has done
the start pulse or not... Something for another day.

merged to togreg branch of iio.git
Thanks.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> ---
>  drivers/iio/adc/ad7476.c |   30 ++++++++++++++++++++++++++----
>  1 file changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index be2098d..7f2f45a 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -23,9 +23,12 @@
>  
>  #define RES_MASK(bits)	((1 << (bits)) - 1)
>  
> +struct ad7476_state;
> +
>  struct ad7476_chip_info {
>  	unsigned int			int_vref_uv;
>  	struct iio_chan_spec		channel[2];
> +	void (*reset)(struct ad7476_state *);
>  };
>  
>  struct ad7476_state {
> @@ -45,6 +48,7 @@ struct ad7476_state {
>  };
>  
>  enum ad7476_supported_device_ids {
> +	ID_AD7091R,
>  	ID_AD7276,
>  	ID_AD7277,
>  	ID_AD7278,
> @@ -79,6 +83,12 @@ done:
>  	return IRQ_HANDLED;
>  }
>  
> +static void ad7091_reset(struct ad7476_state *st)
> +{
> +	/* Any transfers with 8 scl cycles will reset the device */
> +	spi_read(st->spi, st->data, 1);
> +}
> +
>  static int ad7476_scan_direct(struct ad7476_state *st)
>  {
>  	int ret;
> @@ -130,11 +140,11 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  }
>  
> -#define _AD7476_CHAN(bits, _shift)				\
> +#define _AD7476_CHAN(bits, _shift, _info_mask)			\
>  	{							\
>  	.type = IIO_VOLTAGE,					\
>  	.indexed = 1,						\
> -	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |		\
> +	.info_mask = _info_mask |				\
>  	IIO_CHAN_INFO_SCALE_SHARED_BIT,				\
>  	.scan_type = {						\
>  		.sign = 'u',					\
> @@ -145,10 +155,18 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
>  	},							\
>  }
>  
> -#define AD7476_CHAN(bits) _AD7476_CHAN((bits), 13 - (bits))
> -#define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits))
> +#define AD7476_CHAN(bits) _AD7476_CHAN((bits), 13 - (bits), \
> +		IIO_CHAN_INFO_RAW_SEPARATE_BIT)
> +#define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits), \
> +		IIO_CHAN_INFO_RAW_SEPARATE_BIT)
> +#define AD7091R_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), 0)
>  
>  static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
> +	[ID_AD7091R] = {
> +		.channel[0] = AD7091R_CHAN(12),
> +		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> +		.reset = ad7091_reset,
> +	},
>  	[ID_AD7276] = {
>  		.channel[0] = AD7940_CHAN(12),
>  		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> @@ -238,6 +256,9 @@ static int __devinit ad7476_probe(struct spi_device *spi)
>  	if (ret)
>  		goto error_disable_reg;
>  
> +	if (st->chip_info->reset)
> +		st->chip_info->reset(st);
> +
>  	ret = iio_device_register(indio_dev);
>  	if (ret)
>  		goto error_ring_unregister;
> @@ -271,6 +292,7 @@ static int __devexit ad7476_remove(struct spi_device *spi)
>  }
>  
>  static const struct spi_device_id ad7476_id[] = {
> +	{"ad7091r", ID_AD7091R},
>  	{"ad7273", ID_AD7277},
>  	{"ad7274", ID_AD7276},
>  	{"ad7276", ID_AD7276},
>