iio: accel: stk8ba50: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.

Found during an audit of all calls of this function.

Fixes: db6a19b8 ("iio: accel: Add trigger support for STK8BA50")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-8-jic23@kernel.org

drivers/iio/accel/stk8ba50.c

@@ -91,12 +91,11 @@ struct stk8ba50_data {
 	u8 sample_rate_idx;
 	struct iio_trigger *dready_trig;
 	bool dready_trigger_on;
-	/*
-	 * 3 x 16-bit channels (10-bit data, 6-bit padding) +
-	 * 1 x 16 padding +
-	 * 4 x 16 64-bit timestamp
-	 */
-	s16 buffer[8];
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s16 chans[3];
+		s64 timetamp __aligned(8);
+	} scan;
 };
 
 #define STK8BA50_ACCEL_CHANNEL(index, reg, axis) {			\
@@ -324,7 +323,7 @@ static irqreturn_t stk8ba50_trigger_handler(int irq, void *p)
 		ret = i2c_smbus_read_i2c_block_data(data->client,
 						    STK8BA50_REG_XOUT,
 						    STK8BA50_ALL_CHANNEL_SIZE,
-						    (u8 *)data->buffer);
+						    (u8 *)data->scan.chans);
 		if (ret < STK8BA50_ALL_CHANNEL_SIZE) {
 			dev_err(&data->client->dev, "register read failed\n");
 			goto err;
@@ -337,10 +336,10 @@ static irqreturn_t stk8ba50_trigger_handler(int irq, void *p)
 			if (ret < 0)
 				goto err;
 
-			data->buffer[i++] = ret;
+			data->scan.chans[i++] = ret;
 		}
 	}
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   pf->timestamp);
 err:
 	mutex_unlock(&data->lock);