iio: adc: mxs-lradc: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

[ Upstream commit 6a6be221b8bd561b053f0701ec752a5ed9007f69 ]

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.
Add a comment on why the buffer is the size it is as not immediately
obvious.

Found during an audit of all calls of this function.

Fixes: 6dd112b9f85e ("iio: adc: mxs-lradc: Add support for ADC driver")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Andreas Klinger <ak@it-klinger.de>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210613152301.571002-4-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/adc/mxs-lradc-adc.c b/drivers/iio/adc/mxs-lradc-adc.c
index 30e29f44ebd2ee6bf3ac8bc950a8e043f44ae214..c480cb489c1a32afa80bd13a049fe08991afef3f 100644 (file)
--- a/drivers/iio/adc/mxs-lradc-adc.c
+++ b/drivers/iio/adc/mxs-lradc-adc.c
@@ -115,7 +115,8 @@ struct mxs_lradc_adc {
        struct device           *dev;
 
        void __iomem            *base;
-       u32                     buffer[10];
+       /* Maximum of 8 channels + 8 byte ts */
+       u32                     buffer[10] __aligned(8);
        struct iio_trigger      *trig;
        struct completion       completion;
        spinlock_t              lock;