Hi Jacopo,
On Tue, Dec 13, 2016 at 1:37 PM, Jacopo Mondi <[email protected]> wrote:
> Add IIO driver for Maxim MAX11100 single-channel ADC.
> Add DT bindings documentation.
>
> Signed-off-by: Jacopo Mondi <[email protected]>
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -29,6 +29,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
> obj-$(CONFIG_LTC2485) += ltc2485.o
> obj-$(CONFIG_MAX1027) += max1027.o
> +obj-$(CONFIG_MAX11100) += max11100.o
> obj-$(CONFIG_MAX1363) += max1363.o
> obj-$(CONFIG_MCP320X) += mcp320x.o
> obj-$(CONFIG_MCP3422) += mcp3422.o
> diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c
> new file mode 100644
> index 0000000..f372ad8
> --- /dev/null
> +++ b/drivers/iio/adc/max11100.c
> +/*
> + * LSB is the ADC single digital step
> + * 1 LSB = (vref / 2 ^ 16)
> + * AIN = (DIN * LSB)
> + */
> +#define MAX11100_LSB_DIV (1 << 16)
> +#define MAX11100_LSB(vref) (vref / MAX11100_LSB_DIV)
DIV_ROUND_CLOSEST()?
> +struct max11100_state {
> + const struct max11100_chip_desc *desc;
> + struct spi_device *spi;
> + int vref_uv;
unsi
It's good practice to move the smaller members to the end of the structure,
to avoid gaps due to alignment rules (struct mutex needs to be 64-bit aligned
on 64-bit platforms).
> + struct mutex lock;
> +};
> +static struct max11100_chip_desc {
> + unsigned int num_chan;
> + const struct iio_chan_spec *channels;
Same here (but it won't have any effect for now).
> +} max11100_desc = {
> + .num_chan = ARRAY_SIZE(max11100_channels),
> + .channels = max11100_channels,
> +};
> +static int max11100_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + int ret;
> + struct max11100_state *state = iio_priv(indio_dev);
> + uint8_t buffer[3];
> + *val = be16_to_cpu(*(uint16_t *)&buffer[1]);
Reading the uint16_t will be an unaligned load, which is not supported on all
platforms. So you either have to use get_unaligned_le16(), or assemble the
value yourself, like you did in v1.
> + *val = *val * MAX11100_LSB(state->vref_uv) / 1000;
DIV_ROUND_CLOSEST()?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
