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authorMircea Caprioru <mircea.caprioru@analog.com>2019-06-25 11:11:25 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2019-06-26 21:24:21 +0100
commit0eaecea6e4878abbf1d3e8de3e4eeabc856133d4 (patch)
treeeec27e0a77adf0a7b51c30ad24f222a9ad123323
parentf1794fd7bdf7981e21595d0162ab4f7305b3c7c1 (diff)
iio: adc: ad7124: Add buffered input support
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@analog.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
-rw-r--r--drivers/iio/adc/ad7124.c17
1 files 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 @@ err:
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;