[PATCH v5 4/4] iio: adc: ad9467: check for backend capabilities

Tomas Melin
2026-01-30T09:17:33Z

Add capability checks for operation with backends that do not necessarily
support full set of features, but are otherwise compatible with the device.
This ensures a fully functional device, but with limited capabilities.

Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
---
drivers/iio/adc/ad9467.c | 69 ++++++++++++++++++++++++++++++------------------
1 file changed, 43 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index 59c3fa3bcc9b..d768f7bf2a1c 100644
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -913,7 +913,9 @@ static int __ad9467_update_clock(struct ad9467_state *st, long r_clk)
return ret;

guard(mutex)(&st->lock);
- return ad9467_calibrate(st);
+ if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION))
+ return ad9467_calibrate(st);
+ return 0;
}

static int ad9467_write_raw(struct iio_dev *indio_dev,
@@ -1119,12 +1121,15 @@ static ssize_t ad9467_chan_test_mode_read(struct file *file,
len = scnprintf(buf, sizeof(buf), "Running \"%s\" Test:\n\t",
ad9467_test_modes[chan->mode]);

- ret = iio_backend_debugfs_print_chan_status(st->back, chan->idx,
- buf + len,
- sizeof(buf) - len);
- if (ret < 0)
- return ret;
- len += ret;
+ if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) {
+ ret = iio_backend_debugfs_print_chan_status(st->back,
+ chan->idx,
+ buf + len,
+ sizeof(buf) - len);
+ if (ret < 0)
+ return ret;
+ len += ret;
+ }
} else if (chan->mode == AN877_ADC_TESTMODE_OFF) {
len = scnprintf(buf, sizeof(buf), "No test Running...\n");
} else {
@@ -1188,16 +1193,19 @@ static ssize_t ad9467_chan_test_mode_write(struct file *file,
return ret;

/* some patterns have a backend matching monitoring block */
- if (mode == AN877_ADC_TESTMODE_PN9_SEQ) {
- ret = ad9467_backend_testmode_on(st, chan->idx,
+ if (iio_backend_has_caps(st->back,
+ IIO_BACKEND_CAP_CALIBRATION)) {
+ if (mode == AN877_ADC_TESTMODE_PN9_SEQ) {
+ ret = ad9467_backend_testmode_on(st, chan->idx,
IIO_BACKEND_ADI_PRBS_9A);
- if (ret)
- return ret;
- } else if (mode == AN877_ADC_TESTMODE_PN23_SEQ) {
- ret = ad9467_backend_testmode_on(st, chan->idx,
+ if (ret)
+ return ret;
+ } else if (mode == AN877_ADC_TESTMODE_PN23_SEQ) {
+ ret = ad9467_backend_testmode_on(st, chan->idx,
IIO_BACKEND_ADI_PRBS_23A);
- if (ret)
- return ret;
+ if (ret)
+ return ret;
+ }
}
}

@@ -1263,8 +1271,10 @@ static void ad9467_debugfs_init(struct iio_dev *indio_dev)
if (!st->chan_test)
return;

- debugfs_create_file("calibration_table_dump", 0400, d, st,
- &ad9467_calib_table_fops);
+ if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) {
+ debugfs_create_file("calibration_table_dump", 0400, d, st,
+ &ad9467_calib_table_fops);
+ }

for (chan = 0; chan < st->info->num_channels; chan++) {
snprintf(attr_name, sizeof(attr_name), "in_voltage%u_test_mode",
@@ -1339,17 +1349,24 @@ static int ad9467_probe(struct spi_device *spi)
if (ret)
return ret;

- ret = devm_iio_backend_request_buffer(&spi->dev, st->back, indio_dev);
- if (ret)
- return ret;
+ if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_BUFFERING)) {
+ ret = devm_iio_backend_request_buffer(&spi->dev, st->back,
+ indio_dev);
+ if (ret)
+ return ret;
+ }

- ret = devm_iio_backend_enable(&spi->dev, st->back);
- if (ret)
- return ret;
+ if (!iio_backend_has_caps(st->back, IIO_BACKEND_CAP_ALWAYS_ON)) {
+ ret = devm_iio_backend_enable(&spi->dev, st->back);
+ if (ret)
+ return ret;
+ }

- ret = ad9467_calibrate(st);
- if (ret)
- return ret;
+ if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) {
+ ret = ad9467_calibrate(st);
+ if (ret)
+ return ret;
+ }

ret = devm_iio_device_register(&spi->dev, indio_dev);
if (ret)

--
2.47.3