Re: [PATCH v2 3/3] iio: dac: ti-dac082s085: Read chip spec from device table

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 17 Oct 2017 12:42:00 +0200
Lukas Wunner <lukas@wunner.de> wrote:

> The two properties unique to each supported chip, resolution and number
> of channels, are currently gleaned from the chip's name.
> E.g. dac102s085 is a dual channel 10-bit DAC.
>         ^^^
> This was deemed unmaintainable by the subsystem maintainer once the
> driver is extended to support further chips, hence it was requested
> to add an explicit table for chip-specific information and use an
> enum to reference into it.
> 
> This adds 17 LoC without any immediate gain, so make the change in a
> separate commit which can be reverted if we determine in 10 years that
> it was unnecessary.
> 
Good luck with that ;) 
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan
> ---
>  drivers/iio/dac/ti-dac082s085.c | 35 ++++++++++++++++++++++++++---------
>  1 file changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iio/dac/ti-dac082s085.c b/drivers/iio/dac/ti-dac082s085.c
> index 0fefb110be69..2c1556f32574 100644
> --- a/drivers/iio/dac/ti-dac082s085.c
> +++ b/drivers/iio/dac/ti-dac082s085.c
> @@ -20,6 +20,22 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/spi/spi.h>
>  
> +enum { dual_8bit, dual_10bit, dual_12bit, quad_8bit, quad_10bit, quad_12bit };
> +
> +struct ti_dac_spec {
> +	u8 num_channels;
> +	u8 resolution;
> +};
> +
> +static const struct ti_dac_spec ti_dac_spec[] = {
> +	[dual_8bit]  = { .num_channels = 2, .resolution = 8  },
> +	[dual_10bit] = { .num_channels = 2, .resolution = 10 },
> +	[dual_12bit] = { .num_channels = 2, .resolution = 12 },
> +	[quad_8bit]  = { .num_channels = 4, .resolution = 8  },
> +	[quad_10bit] = { .num_channels = 4, .resolution = 10 },
> +	[quad_12bit] = { .num_channels = 4, .resolution = 12 },
> +};
> +
>  /**
>   * struct ti_dac_chip - TI DAC chip
>   * @lock: protects write sequences
> @@ -246,6 +262,7 @@ static const struct iio_info ti_dac_info = {
>  static int ti_dac_probe(struct spi_device *spi)
>  {
>  	struct device *dev = &spi->dev;
> +	const struct ti_dac_spec *spec;
>  	struct ti_dac_chip *ti_dac;
>  	struct iio_dev *indio_dev;
>  	int ret;
> @@ -267,9 +284,9 @@ static int ti_dac_probe(struct spi_device *spi)
>  	spi_message_init_with_transfers(&ti_dac->mesg, &ti_dac->xfer, 1);
>  	ti_dac->mesg.spi = spi;
>  
> -	ret = sscanf(spi->modalias, "dac%2hhu%1d",
> -		     &ti_dac->resolution, &indio_dev->num_channels);
> -	WARN_ON(ret != 2);
> +	spec = &ti_dac_spec[spi_get_device_id(spi)->driver_data];
> +	indio_dev->num_channels = spec->num_channels;
> +	ti_dac->resolution = spec->resolution;
>  
>  	ti_dac->vref = devm_regulator_get(dev, "vref");
>  	if (IS_ERR(ti_dac->vref))
> @@ -325,12 +342,12 @@ MODULE_DEVICE_TABLE(of, ti_dac_of_id);
>  #endif
>  
>  static const struct spi_device_id ti_dac_spi_id[] = {
> -	{ "dac082s085" },
> -	{ "dac102s085" },
> -	{ "dac122s085" },
> -	{ "dac084s085" },
> -	{ "dac104s085" },
> -	{ "dac124s085" },
> +	{ "dac082s085", dual_8bit  },
> +	{ "dac102s085", dual_10bit },
> +	{ "dac122s085", dual_12bit },
> +	{ "dac084s085", quad_8bit  },
> +	{ "dac104s085", quad_10bit },
> +	{ "dac124s085", quad_12bit },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(spi, ti_dac_spi_id);