[PATCH 1/2] iio: adc: ti-ads112c14: add burnout current support
From: David Lechner (TI)
Date: Fri Jul 24 2026 - 16:49:55 EST
Add a custom attribute via ext_info when a channel has a burnout current
specified in the devicetree. This adds an in_{voltageY,resistanceY,
voltageY-voltageX}_burnoutraw sysfs attribute for the channel that
performs a single conversion (same as _raw attribute) except that it
enables the burnout current. The chip also has a restriction that input
chopping cannot be enabled when burnout current is enabled, so we also
disable input chopping when burnout current is active.
Signed-off-by: David Lechner (TI) <dlechner@xxxxxxxxxxxx>
---
drivers/iio/adc/ti-ads112c14.c | 126 ++++++++++++++++++++++++++++++++++++++---
1 file changed, 117 insertions(+), 9 deletions(-)
diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
index f3a2eba55362..0c79bfc0607a 100644
--- a/drivers/iio/adc/ti-ads112c14.c
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -76,6 +76,11 @@
#define ADS112C14_DEVICE_CFG_PWDN BIT(7)
#define ADS112C14_DEVICE_CFG_STBY_MODE BIT(6)
#define ADS112C14_DEVICE_CFG_BOCS GENMASK(5, 4)
+#define ADS112C14_DEVICE_CFG_BOCS_DISABLED 0
+#define ADS112C14_DEVICE_CFG_BOCS_200_nA 1
+#define ADS112C14_DEVICE_CFG_BOCS_1_uA 2
+#define ADS112C14_DEVICE_CFG_BOCS_10_uA 3
+
#define ADS112C14_DEVICE_CFG_CLK_SEL BIT(3)
#define ADS112C14_DEVICE_CFG_CONV_MODE BIT(2)
#define ADS112C14_DEVICE_CFG_CONV_MODE_CONTINUOUS 0
@@ -251,6 +256,7 @@ struct ads112c14_measurement {
u8 idac2_mux;
u8 iadc_count;
u8 gain_val;
+ u8 burnout;
bool global_chop;
bool bipolar;
int scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)][2];
@@ -474,7 +480,8 @@ static const struct regmap_config ads112c14_regmap_config = {
};
static int ads112c14_prepare_measurement_channel(struct ads112c14_data *data,
- const struct iio_chan_spec *chan)
+ const struct iio_chan_spec *chan,
+ bool en_burnout)
{
struct ads112c14_measurement *measurement = &data->measurements[chan->scan_index];
u32 refp_buf_en, refn_buf_en, ref_val, ref_sel;
@@ -528,7 +535,7 @@ static int ads112c14_prepare_measurement_channel(struct ads112c14_data *data,
ret = regmap_update_bits(data->regmap, ADS112C14_REG_DATA_RATE_CFG,
ADS112C14_DATA_RATE_CFG_GC_EN,
FIELD_PREP(ADS112C14_DATA_RATE_CFG_GC_EN,
- measurement->global_chop));
+ measurement->global_chop && !en_burnout));
if (ret)
return ret;
@@ -626,10 +633,11 @@ static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
}
static int ads112c14_prepare_channel(struct ads112c14_data *data,
- const struct iio_chan_spec *chan)
+ const struct iio_chan_spec *chan,
+ bool en_burnout)
{
if (chan->channel < ADS112C14_SYS_MON_CHANNEL_BASE)
- return ads112c14_prepare_measurement_channel(data, chan);
+ return ads112c14_prepare_measurement_channel(data, chan, en_burnout);
return ads112c14_prepare_sys_mon_channel(data, chan);
}
@@ -653,7 +661,7 @@ static int ads112c14_scan_read(struct ads112c14_data *data, u8 *buf)
static int ads112c14_single_conversion(struct ads112c14_data *data,
const struct iio_chan_spec *chan,
- u8 *buf, bool for_scan)
+ u8 *buf, bool en_burnout, bool for_scan)
{
struct i2c_client *client = to_i2c_client(regmap_get_device(data->regmap));
u32 reg_val;
@@ -661,7 +669,7 @@ static int ads112c14_single_conversion(struct ads112c14_data *data,
guard(mutex)(&data->lock);
- ret = ads112c14_prepare_channel(data, chan);
+ ret = ads112c14_prepare_channel(data, chan, en_burnout);
if (ret)
return ret;
@@ -736,7 +744,7 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
if (IIO_DEV_ACQUIRE_FAILED(claim))
return -EBUSY;
- ret = ads112c14_single_conversion(data, chan, buf, false);
+ ret = ads112c14_single_conversion(data, chan, buf, false, false);
if (ret)
return ret;
@@ -999,7 +1007,7 @@ static irqreturn_t ads112c14_trigger_handler(int irq, void *private)
ret = ads112c14_single_conversion(data, chan,
(u8 *)&data->scan[offset++],
- true);
+ false, true);
if (ret) {
dev_err_once(indio_dev->dev.parent,
"failed to read channel %d: %pe; additional errors will be suppressed\n",
@@ -1060,7 +1068,7 @@ static int ads112c14_buffer_postenable(struct iio_dev *indio_dev)
guard(mutex)(&data->lock);
- ret = ads112c14_prepare_channel(data, chan);
+ ret = ads112c14_prepare_channel(data, chan, false);
if (ret)
return ret;
@@ -1109,6 +1117,78 @@ static const struct iio_buffer_setup_ops ads112c14_buffer_setup_ops = {
.validate_scan_mask = ads112c14_validate_scan_mask,
};
+static ssize_t ads112c14_read_burnout_raw(struct iio_dev *indio_dev,
+ uintptr_t private,
+ struct iio_chan_spec const *chan,
+ char *buf)
+{
+ struct ads112c14_data *data = iio_priv(indio_dev);
+ struct ads112c14_measurement *measurement;
+ int ret, ret2, val;
+ u8 raw_buf[3];
+
+ if (chan->channel >= ADS112C14_SYS_MON_CHANNEL_BASE)
+ return -EINVAL;
+
+ measurement = &data->measurements[chan->scan_index];
+
+ if (!measurement->burnout)
+ return -EINVAL;
+
+ IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+ if (IIO_DEV_ACQUIRE_FAILED(claim))
+ return -EBUSY;
+
+ ret = regmap_update_bits(data->regmap, ADS112C14_REG_DEVICE_CFG,
+ ADS112C14_DEVICE_CFG_BOCS,
+ FIELD_PREP(ADS112C14_DEVICE_CFG_BOCS,
+ measurement->burnout));
+ if (ret)
+ return ret;
+
+ ret = ads112c14_single_conversion(data, chan, raw_buf, true, false);
+
+ /*
+ * Important to always turn off burnout current even if the conversion
+ * fails so that it does not affect subsequent measurements. This error
+ * also takes precedence over the conversion error since the device may
+ * be left in a bad state.
+ */
+ ret2 = regmap_update_bits(data->regmap, ADS112C14_REG_DEVICE_CFG,
+ ADS112C14_DEVICE_CFG_BOCS,
+ FIELD_PREP(ADS112C14_DEVICE_CFG_BOCS,
+ ADS112C14_DEVICE_CFG_BOCS_DISABLED));
+ if (ret2)
+ return ret2;
+
+ if (ret < 0)
+ return ret;
+
+ switch (data->chip_info->resolution_bits) {
+ case 16:
+ val = get_unaligned_be16(raw_buf);
+ break;
+ case 24:
+ val = get_unaligned_be24(raw_buf);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (measurement->bipolar)
+ val = sign_extend32(val, data->chip_info->resolution_bits - 1);
+
+ return sysfs_emit(buf, "%d\n", val);
+}
+
+static const struct iio_chan_spec_ext_info ads112c14_ext_info_burnout[] = {
+ {
+ .name = "burnoutraw",
+ .read = ads112c14_read_burnout_raw,
+ },
+ { }
+};
+
static int ads112c14_populate_idac_mag(u32 current_nA, u8 *idac_mag)
{
u32 current_uA = current_nA / (NANO / MICRO);
@@ -1277,6 +1357,34 @@ static int ads112c14_parse_channels(struct iio_dev *indio_dev,
measurement->global_chop = fwnode_property_read_bool(child,
"input-chopping");
+ if (fwnode_property_present(child, "burn-out-current-nanoamp")) {
+ u32 burnout_nA;
+
+ ret = fwnode_property_read_u32(child, "burn-out-current-nanoamp",
+ &burnout_nA);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to read burn-out-current-nanoamp property\n");
+
+ switch (burnout_nA) {
+ case 200:
+ measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_200_nA;
+ break;
+ case 1000:
+ measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_1_uA;
+ break;
+ case 10000:
+ measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_10_uA;
+ break;
+ default:
+ return dev_err_probe(dev, -EINVAL,
+ "invalid burn-out-current-nanoamp value\n");
+ }
+
+ if (measurement->burnout)
+ spec->ext_info = ads112c14_ext_info_burnout;
+ }
+
if (fwnode_property_present(child, "reference-sources")) {
ret = fwnode_property_match_property_string(child,
"reference-sources", ads112c14_vref_source_names,
--
2.43.0