Commit ae5bc07e authored by David Lechner's avatar David Lechner Committed by Jonathan Cameron
Browse files

iio: temperature: maxim_thermocouple: use DMA-safe buffer for spi_read() 



Replace using stack-allocated buffers with a DMA-safe buffer for use
with spi_read(). This allows the driver to be safely used with
DMA-enabled SPI controllers.

The buffer array is also converted to a struct with a union to make the
usage of the memory in the buffer more clear and ensure proper alignment.

Fixes: 1f25ca11 ("iio: temperature: add support for Maxim thermocouple chips")
Signed-off-by: default avatarDavid Lechner <dlechner@baylibre.com>
Reviewed-by: default avatarNuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250721-iio-use-more-iio_declare_buffer_with_ts-3-v2-1-0c68d41ccf6c@baylibre.com


Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 1cfb22c2

drivers/iio/temperature/maxim_thermocouple.c

+16 −10
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/module.h>

#include <linux/err.h>

#include <linux/spi/spi.h>

#include <linux/types.h>

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>

#include <linux/iio/trigger.h>
@@ -121,8 +122,15 @@ struct maxim_thermocouple_data { 
	struct spi_device *spi;

	const struct maxim_thermocouple_chip *chip;

	char tc_type;



	u8 buffer[16] __aligned(IIO_DMA_MINALIGN);

	/* Buffer for reading up to 2 hardware channels. */

	struct {

		union {

			__be16 raw16;

			__be32 raw32;

			__be16 raw[2];

		};

		aligned_s64 timestamp;

	} buffer __aligned(IIO_DMA_MINALIGN);

};



static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
@@ -130,18 +138,16 @@ static int maxim_thermocouple_read(struct maxim_thermocouple_data *data, 
{

	unsigned int storage_bytes = data->chip->read_size;

	unsigned int shift = chan->scan_type.shift + (chan->address * 8);

	__be16 buf16;

	__be32 buf32;

	int ret;



	switch (storage_bytes) {

	case 2:

		ret = spi_read(data->spi, (void *)&buf16, storage_bytes);

		*val = be16_to_cpu(buf16);

		ret = spi_read(data->spi, &data->buffer.raw16, storage_bytes);

		*val = be16_to_cpu(data->buffer.raw16);

		break;

	case 4:

		ret = spi_read(data->spi, (void *)&buf32, storage_bytes);

		*val = be32_to_cpu(buf32);

		ret = spi_read(data->spi, &data->buffer.raw32, storage_bytes);

		*val = be32_to_cpu(data->buffer.raw32);

		break;

	default:

		ret = -EINVAL;
@@ -166,9 +172,9 @@ static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private) 
	struct maxim_thermocouple_data *data = iio_priv(indio_dev);

	int ret;



	ret = spi_read(data->spi, data->buffer, data->chip->read_size);

	ret = spi_read(data->spi, data->buffer.raw, data->chip->read_size);

	if (!ret) {

		iio_push_to_buffers_with_ts(indio_dev, data->buffer,

		iio_push_to_buffers_with_ts(indio_dev, &data->buffer,

					    sizeof(data->buffer),

					    iio_get_time_ns(indio_dev));

	}