On Tue, 25 Jun 2019 11:11:25 +0300
Mircea Caprioru <mircea.caprioru@xxxxxxxxxx> wrote:
> This patch adds the option to enable the buffered mode for positive and
> negative inputs. Each option can be enabled independently.
>
> In buffered mode, the input channel feeds into a high impedance input stage
> of the buffer amplifier. Therefore, the input can tolerate significant
> source impedances and is tailored for direct connection to external
> resistive type sensors such as strain gages or RTDs.
>
> Signed-off-by: Mircea Caprioru <mircea.caprioru@xxxxxxxxxx>
Applied.
Thanks,
Jonathan
> ---
>
> Changelog v2:
> - nothing changed here
>
> Changelog v3:
> - nothing changed here
>
> Changelog v4:
> - nothing changed here
>
> drivers/iio/adc/ad7124.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
> index 810234db9c0d..ab52c5e9ecb1 100644
> --- a/drivers/iio/adc/ad7124.c
> +++ b/drivers/iio/adc/ad7124.c
> @@ -61,6 +61,8 @@
> #define AD7124_CONFIG_REF_SEL(x) FIELD_PREP(AD7124_CONFIG_REF_SEL_MSK, x)
> #define AD7124_CONFIG_PGA_MSK GENMASK(2, 0)
> #define AD7124_CONFIG_PGA(x) FIELD_PREP(AD7124_CONFIG_PGA_MSK, x)
> +#define AD7124_CONFIG_IN_BUFF_MSK GENMASK(7, 6)
> +#define AD7124_CONFIG_IN_BUFF(x) FIELD_PREP(AD7124_CONFIG_IN_BUFF_MSK, x)
>
> /* AD7124_FILTER_X */
> #define AD7124_FILTER_FS_MSK GENMASK(10, 0)
> @@ -108,6 +110,8 @@ struct ad7124_chip_info {
> struct ad7124_channel_config {
> enum ad7124_ref_sel refsel;
> bool bipolar;
> + bool buf_positive;
> + bool buf_negative;
> unsigned int ain;
> unsigned int vref_mv;
> unsigned int pga_bits;
> @@ -473,6 +477,11 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
> else
> st->channel_config[channel].refsel = tmp;
>
> + st->channel_config[channel].buf_positive =
> + of_property_read_bool(child, "adi,buffered-positive");
> + st->channel_config[channel].buf_negative =
> + of_property_read_bool(child, "adi,buffered-negative");
> +
> *chan = ad7124_channel_template;
> chan->address = channel;
> chan->scan_index = channel;
> @@ -492,7 +501,7 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
> static int ad7124_setup(struct ad7124_state *st)
> {
> unsigned int val, fclk, power_mode;
> - int i, ret;
> + int i, ret, tmp;
>
> fclk = clk_get_rate(st->mclk);
> if (!fclk)
> @@ -525,8 +534,12 @@ static int ad7124_setup(struct ad7124_state *st)
> if (ret < 0)
> return ret;
>
> + tmp = (st->channel_config[i].buf_positive << 1) +
> + st->channel_config[i].buf_negative;
> +
> val = AD7124_CONFIG_BIPOLAR(st->channel_config[i].bipolar) |
> - AD7124_CONFIG_REF_SEL(st->channel_config[i].refsel);
> + AD7124_CONFIG_REF_SEL(st->channel_config[i].refsel) |
> + AD7124_CONFIG_IN_BUFF(tmp);
> ret = ad_sd_write_reg(&st->sd, AD7124_CONFIG(i), 2, val);
> if (ret < 0)
> return ret;
