[patch 12/22] input: bcm5974: declare alignment usage

[patch 12/22] input: bcm5974: declare alignment usage

[akpm]

From: "Henrik Rydberg" <rydberg@euromail.se>

Add struct alignment information and add comments to ensure all access of
finger data is two-byte aligned.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/input/mouse/bcm5974.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff -puN drivers/input/mouse/bcm5974.c~input-bcm5974-declare-alignment-usage drivers/input/mouse/bcm5974.c
--- a/drivers/input/mouse/bcm5974.c~input-bcm5974-declare-alignment-usage
+++ a/drivers/input/mouse/bcm5974.c
@@ -110,17 +110,17 @@ enum tp_type {
 	TYPE2			/* button integrated in trackpad */
 };
 
-/* trackpad finger data offsets */
-#define FINGER_TYPE1		26
-#define FINGER_TYPE2		30
+/* trackpad finger data offsets, le16-aligned */
+#define FINGER_TYPE1		(13 * sizeof(__le16))
+#define FINGER_TYPE2		(15 * sizeof(__le16))
 
-/* trackpad button data offsets */
+/* trackpad button data offsets, u8-aligned */
 #define BUTTON_TYPE2		15
 
 /* integrated button capability by configuration */
 #define HAS_INTEGRATED_BUTTON(c)	(c->tp_type == TYPE2)
 
-/* trackpad finger structure */
+/* trackpad finger structure, le16-aligned */
 struct tp_finger {
 	__le16 origin;		/* zero when switching track finger */
 	__le16 abs_x;		/* absolute x coodinate */
@@ -134,7 +134,7 @@ struct tp_finger {
 	__le16 force_minor;	/* trackpad force, minor axis? */
 	__le16 unused[3];	/* zeros */
 	__le16 multi;		/* one finger: varies, more fingers: constant */
-};
+} __attribute__((packed, aligned(2)));
 
 /* trackpad finger data size, empirically at least ten fingers */
 #define SIZEOF_FINGER		sizeof(struct tp_finger)
@@ -321,6 +321,7 @@ static int report_tp_state(struct bcm597
 	if (size < c->tp_offset || (size - c->tp_offset) % SIZEOF_FINGER != 0)
 		return -EIO;
 
+	/* finger data, le16-aligned */
 	f = (const struct tp_finger *)(dev->tp_data + c->tp_offset);
 	raw_n = (size - c->tp_offset) / SIZEOF_FINGER;
 
_