mkbp: Add support for buttons and switches.

Currently, the matrix keyboard protocol does not have support for
handling non-matrixed keys.  This commit adds support for buttons which
do not appear in the keyboard matrix as well as switches.

Additionally, the keyboard FIFO is now just a general MKBP events FIFO
which MKBP events are free to use. Now, buttons and switches wil join
the key matrix event.

BUG=chrome-os-partner:54988
BUG=chrome-os-partner:54976
BUG=chromium:626863
BRANCH=None
TEST=Flash kevin, and verify that keyboard is still functional.
TEST=make -j buildall

CQ-DEPEND=CL:358926

Change-Id: If4ada904cbd5d77823a0710d4671484b198c9d91
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/358633
Commit-Ready: Aseda Aboagye <aaboagye@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 38 insertions, 25 deletions

diff --git a/common/mkbp_event.c b/common/mkbp_event.c
index 60ca19d645..844aaf01f1 100644
--- a/common/mkbp_event.c
+++ b/common/mkbp_event.c
@@ -75,35 +75,49 @@ static int mkbp_get_next_event(struct host_cmd_handler_args *args)
 	uint8_t *resp = args->response;
 	const struct mkbp_event_source *src;
 
-	/*
-	 * Find the next event to service.  We do this in a round-robin
-	 * way to make sure no event gets starved.
-	 */
-	for (i = 0; i < EC_MKBP_EVENT_COUNT; ++i)
-		if (event_is_set((last + i) % EC_MKBP_EVENT_COUNT))
-			break;
-
-	if (i == EC_MKBP_EVENT_COUNT)
-		return EC_RES_ERROR;
+	do {
+		/*
+		 * Find the next event to service.  We do this in a round-robin
+		 * way to make sure no event gets starved.
+		 */
+		for (i = 0; i < EC_MKBP_EVENT_COUNT; ++i)
+			if (event_is_set((last + i) % EC_MKBP_EVENT_COUNT))
+				break;
 
-	evt = (i + last) % EC_MKBP_EVENT_COUNT;
-	last = evt + 1;
+		if (i == EC_MKBP_EVENT_COUNT)
+			return EC_RES_UNAVAILABLE;
 
-	/*
-	 * Clear the event before retrieving the event data in case the
-	 * event source wants to send the same event.
-	 */
-	clear_event(evt);
+		evt = (i + last) % EC_MKBP_EVENT_COUNT;
+		last = evt + 1;
 
-	for (src = __mkbp_evt_srcs; src < __mkbp_evt_srcs_end; ++src)
-		if (src->event_type == evt)
-			break;
+		/*
+		 * Clear the event before retrieving the event data in case the
+		 * event source wants to send the same event.
+		 */
+		clear_event(evt);
 
-	if (src == __mkbp_evt_srcs_end)
-		return EC_RES_ERROR;
+		for (src = __mkbp_evt_srcs; src < __mkbp_evt_srcs_end; ++src)
+			if (src->event_type == evt)
+				break;
+
+		if (src == __mkbp_evt_srcs_end)
+			return EC_RES_ERROR;
+
+		resp[0] = evt; /* Event type */
+
+		/*
+		 * get_data() can return -EC_ERROR_BUSY which indicates that the
+		 * next element in the keyboard FIFO does not match what we were
+		 * called with.  For example, get_data is expecting a keyboard
+		 * matrix, however the next element in the FIFO is a button
+		 * event instead.  Therefore, we have to service that button
+		 * event first.
+		 */
+		data_size = src->get_data(resp + 1);
+		if (data_size == -EC_ERROR_BUSY)
+			set_event(evt);
+	} while (data_size == -EC_ERROR_BUSY);
 
-	resp[0] = evt; /* Event type */
-	data_size = src->get_data(resp + 1);
 	if (data_size < 0)
 		return EC_RES_ERROR;
 	args->response_size = 1 + data_size;
@@ -116,4 +130,3 @@ static int mkbp_get_next_event(struct host_cmd_handler_args *args)
 DECLARE_HOST_COMMAND(EC_CMD_GET_NEXT_EVENT,
 		     mkbp_get_next_event,
 		     EC_VER_MASK(0));
-