The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x ae5bc07ec9f73a41734270ef3f800c5c8a7e0ad3 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025082300-defense-dormitory-d649@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ae5bc07ec9f73a41734270ef3f800c5c8a7e0ad3 Mon Sep 17 00:00:00 2001 From: David Lechner dlechner@baylibre.com Date: Mon, 21 Jul 2025 18:04:04 -0500 Subject: [PATCH] iio: temperature: maxim_thermocouple: use DMA-safe buffer for spi_read() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
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: 1f25ca11d84a ("iio: temperature: add support for Maxim thermocouple chips") Signed-off-by: David Lechner dlechner@baylibre.com Reviewed-by: Nuno Sá nuno.sa@analog.com Link: https://patch.msgid.link/20250721-iio-use-more-iio_declare_buffer_with_ts-3-... Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com
diff --git a/drivers/iio/temperature/maxim_thermocouple.c b/drivers/iio/temperature/maxim_thermocouple.c index cae8e84821d7..205939680fd4 100644 --- a/drivers/iio/temperature/maxim_thermocouple.c +++ b/drivers/iio/temperature/maxim_thermocouple.c @@ -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)); }