iio: imu: adis: ensure proper DMA alignment

Aligning the buffer to the L1 cache is not sufficient in some platforms
as they might have larger cacheline sizes for caches after L1 and thus,
we can't guarantee DMA safety.

That was the whole reason to introduce IIO_DMA_MINALIGN in [1]. Do the same
for the sigma_delta ADCs.

[1]: https://lore.kernel.org/linux-iio/[email protected]/

Fixes: ccd2b52 ("staging:iio: Add common ADIS library")
Signed-off-by: Nuno Sa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Author: nunojsa

include/linux/iio/imu/adis.h

@@ -11,6 +11,7 @@
 
 #include <linux/spi/spi.h>
 #include <linux/interrupt.h>
+#include <linux/iio/iio.h>
 #include <linux/iio/types.h>
 
 #define ADIS_WRITE_REG(reg) ((0x80 | (reg)))
@@ -131,7 +132,7 @@ struct adis {
 	unsigned long		irq_flag;
 	void			*buffer;
 
-	u8			tx[10] ____cacheline_aligned;
+	u8			tx[10] __aligned(IIO_DMA_MINALIGN);
 	u8			rx[4];
 };