[PATCH] iio: amplifiers: ada4250: use DMA-safe memory for regmap_bulk_read()

David Lechner
2025-04-18T18:16:26Z

Use DMA-safe memory instead of stack-allocated memory for the call to
regmap_bulk_read() in the ada4250_init() function as this could be used
directly by a SPI controller.

Also remove unnecessary use of get_unaligned_le16() and explicitly
include linux/types.h e.g. for __le16 while we are fixing this up.

Fixes: 28b4c30bfa5f ("iio: amplifiers: ada4250: add support for ADA4250")
Signed-off-by: David Lechner <dlechner@baylibre.com>
---
drivers/iio/amplifiers/ada4250.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/amplifiers/ada4250.c b/drivers/iio/amplifiers/ada4250.c
index 74f8429d652b17b4d1f38366e23ce6a2b3e9b218..f81438460aa51ce30f8f605c60ee5be5c8c251d3 100644
--- a/drivers/iio/amplifiers/ada4250.c
+++ b/drivers/iio/amplifiers/ada4250.c
@@ -13,8 +13,7 @@
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
-
-#include <linux/unaligned.h>
+#include <linux/types.h>

/* ADA4250 Register Map */
#define ADA4250_REG_GAIN_MUX 0x00
@@ -63,6 +62,7 @@ struct ada4250_state {
u8 gain;
int offset_uv;
bool refbuf_en;
+ __le16 reg_val_16 __aligned(IIO_DMA_MINALIGN);
};

/* ADA4250 Current Bias Source Settings: Disabled, Bandgap Reference, AVDD */
@@ -301,7 +301,6 @@ static int ada4250_init(struct ada4250_state *st)
{
int ret;
u16 chip_id;
- u8 data[2] __aligned(8) = {};
struct spi_device *spi = st->spi;

st->refbuf_en = device_property_read_bool(&spi->dev, "adi,refbuf-enable");
@@ -326,11 +325,12 @@ static int ada4250_init(struct ada4250_state *st)
if (ret)
return ret;

- ret = regmap_bulk_read(st->regmap, ADA4250_REG_CHIP_ID, data, 2);
+ ret = regmap_bulk_read(st->regmap, ADA4250_REG_CHIP_ID, &st->reg_val_16,
+ sizeof(st->reg_val_16));
if (ret)
return ret;

- chip_id = get_unaligned_le16(data);
+ chip_id = le16_to_cpu(st->reg_val_16);

if (chip_id != ADA4250_CHIP_ID) {
dev_err(&spi->dev, "Invalid chip ID.\n");

---
base-commit: aff301f37e220970c2f301b5c65a8bfedf52058e
change-id: 20250418-iio-amplifiers-ada4250-simplify-data-buffer-in-init-93ebb1344295

Best regards,
--
David Lechner <dlechner@baylibre.com>