[PATCH v5 4/4] iio: adc: ltc2378: Enable triggered buffer data capture
From: Marcelo Schmitt
Date: Thu Jul 02 2026 - 17:46:57 EST
Enable users to run triggered data captures with LTC2378 and similar ADCs.
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
---
Change log v4 -> v5:
- Dropped error message on devm_iio_triggered_buffer_setup() fail.
drivers/iio/adc/Kconfig | 1 +
drivers/iio/adc/ltc2378.c | 75 +++++++++++++++++++++++++++------------
2 files changed, 53 insertions(+), 23 deletions(-)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 8d2fadbf74b1..ac162425dc91 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -950,6 +950,7 @@ config LTC2378
select IIO_BUFFER
select IIO_BUFFER_DMA
select IIO_BUFFER_DMAENGINE
+ select IIO_TRIGGERED_BUFFER
select SPI_OFFLOAD
select SPI_OFFLOAD_TRIGGER_PWM
help
diff --git a/drivers/iio/adc/ltc2378.c b/drivers/iio/adc/ltc2378.c
index b25602d91bbe..bcaecd484ab3 100644
--- a/drivers/iio/adc/ltc2378.c
+++ b/drivers/iio/adc/ltc2378.c
@@ -6,6 +6,7 @@
* Author: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
*/
+#include <linux/array_size.h>
#include <linux/bitops.h>
#include <linux/bits.h>
#include <linux/cleanup.h>
@@ -28,6 +29,8 @@
#include <linux/iio/buffer-dmaengine.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
#include <linux/iio/types.h>
#define LTC2378_TDSDOBUSYL_NS 5
@@ -67,7 +70,7 @@
struct ltc2378_chip_info {
const char *name;
unsigned int internal_ref_uV;
- struct iio_chan_spec chan;
+ struct iio_chan_spec chan[2]; /* 1 physical chan + 1 timestamp chan */
struct iio_chan_spec offload_chan;
unsigned int max_sample_rate_Hz;
unsigned int tconv_ns;
@@ -107,7 +110,7 @@ struct ltc2378_state {
static const struct ltc2378_chip_info ltc2338_18_chip_info = {
.name = "ltc2338-18",
.internal_ref_uV = 4096000,
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 527,
@@ -115,7 +118,7 @@ static const struct ltc2378_chip_info ltc2338_18_chip_info = {
static const struct ltc2378_chip_info ltc2364_16_chip_info = {
.name = "ltc2364-16",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 250 * HZ_PER_KHZ,
.tconv_ns = 3000,
@@ -123,7 +126,7 @@ static const struct ltc2378_chip_info ltc2364_16_chip_info = {
static const struct ltc2378_chip_info ltc2364_18_chip_info = {
.name = "ltc2364-18",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 250 * HZ_PER_KHZ,
.tconv_ns = 3000,
@@ -131,7 +134,7 @@ static const struct ltc2378_chip_info ltc2364_18_chip_info = {
static const struct ltc2378_chip_info ltc2367_16_chip_info = {
.name = "ltc2367-16",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 500 * HZ_PER_KHZ,
.tconv_ns = 1500,
@@ -139,7 +142,7 @@ static const struct ltc2378_chip_info ltc2367_16_chip_info = {
static const struct ltc2378_chip_info ltc2367_18_chip_info = {
.name = "ltc2367-18",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 500 * HZ_PER_KHZ,
.tconv_ns = 1500,
@@ -147,7 +150,7 @@ static const struct ltc2378_chip_info ltc2367_18_chip_info = {
static const struct ltc2378_chip_info ltc2368_16_chip_info = {
.name = "ltc2368-16",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 527,
@@ -155,7 +158,7 @@ static const struct ltc2378_chip_info ltc2368_16_chip_info = {
static const struct ltc2378_chip_info ltc2368_18_chip_info = {
.name = "ltc2368-18",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 527,
@@ -163,7 +166,7 @@ static const struct ltc2378_chip_info ltc2368_18_chip_info = {
static const struct ltc2378_chip_info ltc2369_18_chip_info = {
.name = "ltc2369-18",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 1600 * HZ_PER_KHZ,
.tconv_ns = 412,
@@ -171,7 +174,7 @@ static const struct ltc2378_chip_info ltc2369_18_chip_info = {
static const struct ltc2378_chip_info ltc2370_16_chip_info = {
.name = "ltc2370-16",
- .chan = LTC2378_UNIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_UNIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_UNIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 2 * HZ_PER_MHZ,
.tconv_ns = 322,
@@ -179,7 +182,7 @@ static const struct ltc2378_chip_info ltc2370_16_chip_info = {
static const struct ltc2378_chip_info ltc2376_16_chip_info = {
.name = "ltc2376-16",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 250 * HZ_PER_KHZ,
.tconv_ns = 3000,
@@ -187,7 +190,7 @@ static const struct ltc2378_chip_info ltc2376_16_chip_info = {
static const struct ltc2378_chip_info ltc2376_18_chip_info = {
.name = "ltc2376-18",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 250 * HZ_PER_KHZ,
.tconv_ns = 3000,
@@ -195,7 +198,7 @@ static const struct ltc2378_chip_info ltc2376_18_chip_info = {
static const struct ltc2378_chip_info ltc2376_20_chip_info = {
.name = "ltc2376-20",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(20),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(20), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(20),
.max_sample_rate_Hz = 250 * HZ_PER_KHZ,
.tconv_ns = 3000,
@@ -203,7 +206,7 @@ static const struct ltc2378_chip_info ltc2376_20_chip_info = {
static const struct ltc2378_chip_info ltc2377_16_chip_info = {
.name = "ltc2377-16",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 500 * HZ_PER_KHZ,
.tconv_ns = 1500,
@@ -211,7 +214,7 @@ static const struct ltc2378_chip_info ltc2377_16_chip_info = {
static const struct ltc2378_chip_info ltc2377_18_chip_info = {
.name = "ltc2377-18",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 500 * HZ_PER_KHZ,
.tconv_ns = 1500,
@@ -219,7 +222,7 @@ static const struct ltc2378_chip_info ltc2377_18_chip_info = {
static const struct ltc2378_chip_info ltc2377_20_chip_info = {
.name = "ltc2377-20",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(20),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(20), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(20),
.max_sample_rate_Hz = 500 * HZ_PER_KHZ,
.tconv_ns = 1500,
@@ -227,7 +230,7 @@ static const struct ltc2378_chip_info ltc2377_20_chip_info = {
static const struct ltc2378_chip_info ltc2378_16_chip_info = {
.name = "ltc2378-16",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 527,
@@ -235,7 +238,7 @@ static const struct ltc2378_chip_info ltc2378_16_chip_info = {
static const struct ltc2378_chip_info ltc2378_18_chip_info = {
.name = "ltc2378-18",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 527,
@@ -243,7 +246,7 @@ static const struct ltc2378_chip_info ltc2378_18_chip_info = {
static const struct ltc2378_chip_info ltc2378_20_chip_info = {
.name = "ltc2378-20",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(20),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(20), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(20),
.max_sample_rate_Hz = 1 * HZ_PER_MHZ,
.tconv_ns = 675,
@@ -251,7 +254,7 @@ static const struct ltc2378_chip_info ltc2378_20_chip_info = {
static const struct ltc2378_chip_info ltc2379_18_chip_info = {
.name = "ltc2379-18",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(18),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(18), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(18),
.max_sample_rate_Hz = 1600 * HZ_PER_KHZ,
.tconv_ns = 412,
@@ -259,7 +262,7 @@ static const struct ltc2378_chip_info ltc2379_18_chip_info = {
static const struct ltc2378_chip_info ltc2380_16_chip_info = {
.name = "ltc2380-16",
- .chan = LTC2378_BIPOLAR_DIFF_CHANNEL(16),
+ .chan = { LTC2378_BIPOLAR_DIFF_CHANNEL(16), IIO_CHAN_SOFT_TIMESTAMP(1) },
.offload_chan = LTC2378_OFFLOAD_BIPOLAR_DIFF_CHANNEL(16),
.max_sample_rate_Hz = 2 * HZ_PER_MHZ,
.tconv_ns = 322,
@@ -278,6 +281,25 @@ static int ltc2378_convert_and_acquire(struct ltc2378_state *st)
return ret;
}
+static irqreturn_t ltc2378_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct ltc2378_state *st = iio_priv(indio_dev);
+ int ret;
+
+ ret = ltc2378_convert_and_acquire(st);
+ if (ret < 0)
+ goto err_out;
+
+ iio_push_to_buffers_with_ts(indio_dev, &st->scan, sizeof(st->scan),
+ pf->timestamp);
+
+err_out:
+ iio_trigger_notify_done(indio_dev->trig);
+ return IRQ_HANDLED;
+}
+
static int ltc2378_channel_single_read(const struct iio_chan_spec *chan,
struct ltc2378_state *st, int *val)
{
@@ -658,8 +680,15 @@ static int ltc2378_probe(struct spi_device *spi)
/* Fall back to low speed usage when no SPI offload is available. */
if (ret == -ENODEV) {
indio_dev->info = <c2378_iio_info;
- indio_dev->channels = &st->info->chan;
- indio_dev->num_channels = 1;
+ indio_dev->channels = st->info->chan;
+ indio_dev->num_channels = ARRAY_SIZE(st->info->chan);
+
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+ iio_pollfunc_store_time,
+ ltc2378_trigger_handler,
+ NULL);
+ if (ret)
+ return ret;
} else if (ret) {
return dev_err_probe(dev, ret, "failed to get offload\n");
} else {
--
2.53.0