On Fri, 13 Dec 2024 18:44:42 +0200
Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx> wrote:
> Add support for selecting the data format within the AXI ADC ip.
>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>
One trivial comment inline. If the discussion around David's
question resolves and this is all that is left, I can either tweak
this or we can just decide the long name is fine.
Jonathan
> ---
> changes in v8:
> - provide inline comments explaning the packet formats as requested in
> previous review.
> drivers/iio/adc/adi-axi-adc.c | 46 +++++++++++++++++++++++++++++++++++
> 1 file changed, 46 insertions(+)
>
> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index f6475bc93796..9a3968769512 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -45,6 +45,12 @@
> #define ADI_AXI_ADC_REG_CTRL 0x0044
> #define ADI_AXI_ADC_CTRL_DDR_EDGESEL_MASK BIT(1)
>
> +#define ADI_AXI_ADC_REG_CNTRL_3 0x004c
> +#define AD485X_CNTRL_3_CUSTOM_CTRL_PACKET_FORMAT_MSK GENMASK(1, 0)
I guess this rather long name is straight out of the datasheet / RTL but
maybe..
#define AD485X_CNTRL_3_PACKET_FORMAT_MSK GENMASK(1, 0)
Is enough?
> +#define AD485X_PACKET_FORMAT_20BIT 0x0
> +#define AD485X_PACKET_FORMAT_24BIT 0x1
> +#define AD485X_PACKET_FORMAT_32BIT 0x2
> +
> #define ADI_AXI_ADC_REG_DRP_STATUS 0x0074
> #define ADI_AXI_ADC_DRP_LOCKED BIT(17)
>
> @@ -312,6 +318,45 @@ static int axi_adc_interface_type_get(struct iio_backend *back,
> return 0;
> }
>
> +static int axi_adc_data_size_set(struct iio_backend *back, unsigned int size)
> +{
> + struct adi_axi_adc_state *st = iio_backend_get_priv(back);
> + unsigned int val;
> +
> + switch (size) {
> + /*
> + * There are two different variants of the AXI AD485X IP block, a 16-bit
> + * and a 20-bit variant.
> + * The 0x0 value (AD485X_PACKET_FORMAT_20BIT) is corresponding also to
> + * the 16-bit variant of the IP block.
> + */
> + case 16:
> + case 20:
> + val = AD485X_PACKET_FORMAT_20BIT;
> + break;
> + case 24:
> + val = AD485X_PACKET_FORMAT_24BIT;
> + break;
> + /*
> + * The 0x2 (AD485X_PACKET_FORMAT_32BIT) corresponds only to the 20-bit
> + * variant of the IP block. Setting this value properly is ensured by
> + * the upper layers of the drivers calling the axi-adc functions.
> + * Also, for 16-bit IP block, the 0x2 (AD485X_PACKET_FORMAT_32BIT)
> + * value is handled as maximum size available which is 24-bit for this
> + * configuration.
> + */
> + case 32:
> + val = AD485X_PACKET_FORMAT_32BIT;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return regmap_update_bits(st->regmap, ADI_AXI_ADC_REG_CNTRL_3,
> + AD485X_CNTRL_3_CUSTOM_CTRL_PACKET_FORMAT_MSK,
> + FIELD_PREP(AD485X_CNTRL_3_CUSTOM_CTRL_PACKET_FORMAT_MSK, val));
Yikes. See suggests for names above. I think we need to shorted that define
at least a little to improve readability.
> +}
> +
> static struct iio_buffer *axi_adc_request_buffer(struct iio_backend *back,
> struct iio_dev *indio_dev)
> {
> @@ -360,6 +405,7 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
> .test_pattern_set = axi_adc_test_pattern_set,
> .chan_status = axi_adc_chan_status,
> .interface_type_get = axi_adc_interface_type_get,
> + .data_size_set = axi_adc_data_size_set,
> .debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
> .debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
> };
