mfd: cros-ec: Increase maximum mkbp event size

Having a 16 byte mkbp event size makes it possible to send CEC
messages from the EC to the AP directly inside the mkbp event
instead of first doing a notification and then a read.

Signed-off-by: Stefan Adolfsson <sadolfsson@chromium.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/platform/chrome/cros_ec_proto.c

@@ -506,10 +506,31 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
 }
 EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
 
+static int get_next_event_xfer(struct cros_ec_device *ec_dev,
+			       struct cros_ec_command *msg,
+			       int version, uint32_t size)
+{
+	int ret;
+
+	msg->version = version;
+	msg->command = EC_CMD_GET_NEXT_EVENT;
+	msg->insize = size;
+	msg->outsize = 0;
+
+	ret = cros_ec_cmd_xfer(ec_dev, msg);
+	if (ret > 0) {
+		ec_dev->event_size = ret - 1;
+		memcpy(&ec_dev->event_data, msg->data, ec_dev->event_size);
+	}
+
+	return ret;
+}
+
 static int get_next_event(struct cros_ec_device *ec_dev)
 {
 	u8 buffer[sizeof(struct cros_ec_command) + sizeof(ec_dev->event_data)];
 	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
+	static int cmd_version = 1;
 	int ret;
 
 	if (ec_dev->suspended) {
@@ -517,18 +538,19 @@ static int get_next_event(struct cros_ec_device *ec_dev)
 		return -EHOSTDOWN;
 	}
 
-	msg->version = 0;
+	if (cmd_version == 1) {
-	msg->command = EC_CMD_GET_NEXT_EVENT;
+		ret = get_next_event_xfer(ec_dev, msg, cmd_version,
-	msg->insize = sizeof(ec_dev->event_data);
+				sizeof(struct ec_response_get_next_event_v1));
-	msg->outsize = 0;
+		if (ret < 0 || msg->result != EC_RES_INVALID_VERSION)
+			return ret;
 
-	ret = cros_ec_cmd_xfer(ec_dev, msg);
+		/* Fallback to version 0 for future send attempts */
-	if (ret > 0) {
+		cmd_version = 0;
-		ec_dev->event_size = ret - 1;
-		memcpy(&ec_dev->event_data, msg->data,
-		       sizeof(ec_dev->event_data));
 	}
 
+	ret = get_next_event_xfer(ec_dev, msg, cmd_version,
+				  sizeof(struct ec_response_get_next_event));
+
 	return ret;
 }
 

include/linux/mfd/cros_ec.h

@@ -147,7 +147,7 @@ struct cros_ec_device {
 	bool mkbp_event_supported;
 	struct blocking_notifier_head event_notifier;
 
-	struct ec_response_get_next_event event_data;
+	struct ec_response_get_next_event_v1 event_data;
 	int event_size;
 	u32 host_event_wake_mask;
 };

include/linux/mfd/cros_ec_commands.h

@@ -2093,12 +2093,28 @@ union ec_response_get_next_data {
 	uint32_t   sysrq;
 } __packed;
 
+union ec_response_get_next_data_v1 {
+	uint8_t key_matrix[16];
+	uint32_t host_event;
+	uint32_t buttons;
+	uint32_t switches;
+	uint32_t sysrq;
+	uint32_t cec_events;
+	uint8_t cec_message[16];
+} __packed;
+
 struct ec_response_get_next_event {
 	uint8_t event_type;
 	/* Followed by event data if any */
 	union ec_response_get_next_data data;
 } __packed;
 
+struct ec_response_get_next_event_v1 {
+	uint8_t event_type;
+	/* Followed by event data if any */
+	union ec_response_get_next_data_v1 data;
+} __packed;
+
 /* Bit indices for buttons and switches.*/
 /* Buttons */
 #define EC_MKBP_POWER_BUTTON	0