[PATCH v6 01/10] iio: adc: ad7124: Don't create more channels than the driver can handle

Uwe Kleine-König
2024-12-06T17:29:14Z

The ad7124-4 and ad7124-8 both support 16 channel registers and assigns
each channel defined in dt statically such a register. While the driver
could be a bit more clever about this, it currently isn't and specifying
more than 16 channels yields broken behaviour. So just refuse to bind in
this situation.

Fixes: b3af341bbd96 ("iio: adc: Add ad7124 support")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
drivers/iio/adc/ad7124.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 8d94bc2b1cac..5352b26bb391 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -821,6 +821,16 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
if (!st->num_channels)
return dev_err_probe(dev, -ENODEV, "no channel children\n");

+ /*
+ * The driver assigns each logical channel defined in the device tree
+ * statically one channel register. So only accept 16 such logical
+ * channels to not treat CONFIG_0 (i.e. the register following
+ * CHANNEL_15) as an additional channel register. The driver could be
+ * improved to lift this limitation.
+ */
+ if (st->num_channels > AD7124_MAX_CHANNELS)
+ return dev_err_probe(dev, -EINVAL, "Too many channels defined\n");
+
chan = devm_kcalloc(indio_dev->dev.parent, st->num_channels,
sizeof(*chan), GFP_KERNEL);
if (!chan)
--
2.45.2