iio: imu: bno055: add explicit scan buf layout

Move the scan buf.chans array into a union along with a struct that
gives the layout of the buffer with all channels enabled.

Although not technically required in this case, if there had been a
different number of items before the quaternion, there could have been
a subtle bug with the special alignment needed for the quaternion
channel data and the array would have been too small.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/imu/bno055/bno055.c b/drivers/iio/imu/bno055/bno055.c
index c96fec2ebb3e7852ba0dc01809e1f8aab9375447..d0101607a9b3ad071aec5e28fc225259c9ac0c57 100644 (file)
--- a/drivers/iio/imu/bno055/bno055.c
+++ b/drivers/iio/imu/bno055/bno055.c
@@ -210,9 +210,30 @@ struct bno055_priv {
        u8 uid[BNO055_UID_LEN];
        struct gpio_desc *reset_gpio;
        bool sw_reset;
-       struct {
-               __le16 chans[BNO055_SCAN_CH_COUNT];
-               aligned_s64 timestamp;
+       union {
+               IIO_DECLARE_BUFFER_WITH_TS(__le16, chans, BNO055_SCAN_CH_COUNT);
+               /*
+                * This struct is not used, but it is here to ensure proper size
+                * and alignment of the scan buffer above (because of the extra
+                * requirements of the quaternion field). Technically it is not
+                * needed in this case, because other fields just happen to make
+                * things correctly aligned already. But it is better to be
+                * explicit about the requirements anyway. The actual contents
+                * of the scan buffer will vary depending on which channels are
+                * enabled.
+                */
+               struct {
+                       __le16 acc[3];
+                       __le16 magn[3];
+                       __le16 gyr[3];
+                       __le16 yaw;
+                       __le16 pitch;
+                       __le16 roll;
+                       IIO_DECLARE_QUATERNION(__le16, quaternion);
+                       __le16 lia[3];
+                       __le16 gravity[3];
+                       aligned_s64 timestamp;
+               };
        } buf;
        struct dentry *debugfs;
 };