MKBP event signalling implementation

This implements a new API for EC modules to define MKBP event sources
and send MKBP event to the AP. Also, a new host command
EC_CMD_GET_NEXT_EVENT is added for the AP to query the pending MKBP
events. Each event type may have custom event data sent along with the
event.

BRANCH=None
BUG=chrome-os-partner:33194
TEST=Enable MKBP event on Ryu. Set a host event from EC console, run
'ectool nextevent', and see MKBP event 0x01 (HOST_EVENT) and the set
host event.

Signed-off-by: Vic Yang <victoryang@chromium.org>
Change-Id: I28a1b7e826bcc102bbe39016c9bb3e37d125664c
Reviewed-on: https://chromium-review.googlesource.com/224905
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 95 insertions, 0 deletions

diff --git a/common/mkbp_event.c b/common/mkbp_event.c
new file mode 100644
index 0000000000..d78db48a2d
--- /dev/null
+++ b/common/mkbp_event.c
@@ -0,0 +1,95 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Event handling in MKBP keyboard protocol
+ */
+
+#include "atomic.h"
+#include "gpio.h"
+#include "host_command.h"
+#include "link_defs.h"
+#include "mkbp_event.h"
+#include "util.h"
+
+static uint32_t events;
+
+static void set_event(uint8_t event_type)
+{
+	atomic_or(&events, 1 << event_type);
+}
+
+static void clear_event(uint8_t event_type)
+{
+	atomic_clear(&events, 1 << event_type);
+}
+
+static int event_is_set(uint8_t event_type)
+{
+	return events & (1 << event_type);
+}
+
+/**
+ * Assert host keyboard interrupt line.
+ */
+static void set_host_interrupt(int active)
+{
+	/* interrupt host by using active low EC_INT signal */
+	gpio_set_level(GPIO_EC_INT, !active);
+}
+
+void mkbp_send_event(uint8_t event_type)
+{
+	set_event(event_type);
+	set_host_interrupt(1);
+}
+
+static int mkbp_get_next_event(struct host_cmd_handler_args *args)
+{
+	static int last;
+	int i, data_size, evt;
+	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;
+
+	evt = (i + last) % EC_MKBP_EVENT_COUNT;
+	last = evt + 1;
+
+	/*
+	 * Clear the event before retrieving the event data in case the
+	 * event source wants to send the same event.
+	 */
+	clear_event(evt);
+
+	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 */
+	data_size = src->get_data(resp + 1);
+	if (data_size < 0)
+		return EC_RES_ERROR;
+	args->response_size = 1 + data_size;
+
+	if (!events)
+		set_host_interrupt(0);
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_GET_NEXT_EVENT,
+		     mkbp_get_next_event,
+		     EC_VER_MASK(0));
+