[PATCH 3/3] iio: adc: ti-ads112c14: add support for buffered read
From: David Lechner (TI)
Date: Tue Jul 14 2026 - 20:20:56 EST
Add support for buffered reads using a triggered buffer.
The device has a continuous conversion mode, but that can only be used
with one channel at a time since there is nothing like a sequencer to
support that in hardware. Instead, we use single-shot reads like we do
for direct reads to be able to read multiple channels.
Support for continuous conversion mode could be added in the future if
needed via a 2nd buffer.
Signed-off-by: David Lechner (TI) <dlechner@xxxxxxxxxxxx>
---
drivers/iio/adc/ti-ads112c14.c | 103 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 99 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
index 99ccacd6d56f..1404ca31324b 100644
--- a/drivers/iio/adc/ti-ads112c14.c
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -15,7 +15,10 @@
#include <linux/dev_printk.h>
#include <linux/device/devres.h>
#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
#include <linux/math64.h>
#include <linux/minmax.h>
#include <linux/module.h>
@@ -29,6 +32,9 @@
#include <linux/unaligned.h>
#include <linux/units.h>
+/* Arbitrary limit since channels are dynamic. */
+#define ADS112C14_MAX_MEASUREMENT_CHANNELS 16
+
/* Datasheet t_d(RST) - time to wait after reset before next I2C use. */
#define ADS112C14_DELAY_RESET_US 500
@@ -255,6 +261,8 @@ struct ads112c14_data {
u32 num_measurements;
u8 sys_mon_chan_short_gain_val;
int sys_mon_chan_short_scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)][2];
+ IIO_DECLARE_BUFFER_WITH_TS(__be32, scan, ADS112C14_MAX_MEASUREMENT_CHANNELS +
+ ARRAY_SIZE(ads112c14_sys_mon_channels));
};
static bool ads112c14_writeable_reg(struct device *dev, unsigned int reg)
@@ -575,7 +583,7 @@ static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
static int ads112c14_single_conversion(struct ads112c14_data *data,
const struct iio_chan_spec *chan,
- u8 *buf)
+ u8 *buf, bool for_scan)
{
struct i2c_client *client = to_i2c_client(regmap_get_device(data->regmap));
u32 reg_val;
@@ -605,6 +613,22 @@ static int ads112c14_single_conversion(struct ads112c14_data *data,
if (ret)
return ret;
+ /*
+ * When doing buffered read, we don't check the CRC, but rather pass it
+ * along with the raw data.
+ */
+ if (for_scan) {
+ u8 len = BITS_TO_BYTES(data->chip_info->resolution_bits) +
+ (data->i2c_crc_enabled ? 1 : 0);
+
+ ret = i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA,
+ len, buf);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+ }
+
return ads112c14_i2c_read_bytes(client, ADS112C14_CMD_RDATA, buf,
BITS_TO_BYTES(data->chip_info->resolution_bits),
data->i2c_crc_enabled);
@@ -639,7 +663,7 @@ 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);
+ ret = ads112c14_single_conversion(data, chan, buf, false);
if (ret < 0)
return ret;
@@ -765,6 +789,10 @@ static int ads112c14_write_raw(struct iio_dev *indio_dev,
const int (*scale_avail)[2];
u8 *gain_val;
+ IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+ if (IIO_DEV_ACQUIRE_FAILED(claim))
+ return -EBUSY;
+
switch (mask) {
case IIO_CHAN_INFO_SCALE: {
guard(mutex)(&data->lock);
@@ -863,6 +891,37 @@ static int ads112c14_read_label(struct iio_dev *indio_dev,
return sysfs_emit(label, "%s\n", label_source);
}
+static irqreturn_t ads112c14_trigger_handler(int irq, void *private)
+{
+ struct iio_poll_func *pf = private;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct ads112c14_data *data = iio_priv(indio_dev);
+ u32 offset = 0;
+ u32 i;
+ int ret;
+
+ iio_for_each_active_channel(indio_dev, i) {
+ const struct iio_chan_spec *chan = &indio_dev->channels[i];
+
+ ret = ads112c14_single_conversion(data, chan,
+ (u8 *)&data->scan[offset++],
+ true);
+ if (ret) {
+ dev_err_once(indio_dev->dev.parent,
+ "failed to read channel %d: %pe; additional errors will be suppressed\n",
+ chan->channel, ERR_PTR(ret));
+ goto out;
+ }
+ }
+
+ iio_push_to_buffers_with_ts(indio_dev, data->scan,
+ sizeof(data->scan), pf->timestamp);
+out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
static const struct iio_info ads112c14_info = {
.read_raw = ads112c14_read_raw,
.read_avail = ads112c14_read_avail,
@@ -908,7 +967,7 @@ static int ads112c14_parse_channels(struct iio_dev *indio_dev,
return -ENOMEM;
channels = devm_kcalloc(dev, num_child_nodes +
- ARRAY_SIZE(ads112c14_sys_mon_channels),
+ ARRAY_SIZE(ads112c14_sys_mon_channels) + 1,
sizeof(*channels), GFP_KERNEL);
if (!channels)
return -ENOMEM;
@@ -1069,14 +1128,44 @@ static int ads112c14_parse_channels(struct iio_dev *indio_dev,
if (spec->type == IIO_RESISTANCE)
spec->differential = 0;
+ spec->scan_type = (struct iio_scan_type){
+ .format = measurement->bipolar ?
+ IIO_SCAN_FORMAT_SIGNED_INT :
+ IIO_SCAN_FORMAT_UNSIGNED_INT,
+ .realbits = data->chip_info->resolution_bits,
+ .storagebits = 32,
+ .shift = 32 - data->chip_info->resolution_bits,
+ .endianness = IIO_BE,
+ };
+
i++;
}
data->num_measurements = i;
+ if (data->num_measurements >= ADS112C14_MAX_MEASUREMENT_CHANNELS)
+ return dev_err_probe(dev, -EINVAL,
+ "too many measurement channels defined\n");
+
memcpy(channels + i, ads112c14_sys_mon_channels, sizeof(ads112c14_sys_mon_channels));
+ for (u32 j = 0; j < ARRAY_SIZE(ads112c14_sys_mon_channels); j++) {
+ struct iio_chan_spec *spec = &channels[i + j];
+
+ spec->scan_index = i + j;
+ spec->scan_type = (struct iio_scan_type){
+ .format = IIO_SCAN_FORMAT_SIGNED_INT,
+ .realbits = data->chip_info->resolution_bits,
+ .storagebits = 32,
+ .shift = 32 - data->chip_info->resolution_bits,
+ .endianness = IIO_BE,
+ };
+ }
+
indio_dev->channels = channels;
- indio_dev->num_channels = i + ARRAY_SIZE(ads112c14_sys_mon_channels);
+ indio_dev->num_channels = i + ARRAY_SIZE(ads112c14_sys_mon_channels) + 1;
+
+ i = indio_dev->num_channels - 1;
+ channels[i] = IIO_CHAN_SOFT_TIMESTAMP(i);
return 0;
}
@@ -1304,6 +1393,12 @@ static int ads112c14_probe(struct i2c_client *client)
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &ads112c14_info;
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+ iio_pollfunc_store_time,
+ ads112c14_trigger_handler, NULL);
+ if (ret)
+ return ret;
+
return devm_iio_device_register(dev, indio_dev);
}
--
2.43.0