media: cros-ec-cec: Support receiving messages from multiple ports

Currently, received messages are sent from the EC in the cec_message
MKBP event. Since the size of ec_response_get_next_data_v1 is 16 bytes,
which is also the maximum size of a CEC message, there is no space to
add a port parameter. Increasing the size of
ec_response_get_next_data_v1 is an option, but this would increase
EC-kernel traffic for all MKBP event types.

Instead, use an event to notify that data is ready, and add a new read
command to read the data.

For backwards compatibility with old EC firmware, continue to handle
cec_message events as well.

Signed-off-by: Reka Norman <rekanorman@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
index b7e8573a8a49..ad61c7ff0b28 100644
--- a/include/linux/platform_data/cros_ec_commands.h
+++ b/include/linux/platform_data/cros_ec_commands.h
@@ -4473,6 +4473,27 @@ struct ec_params_cec_write_v1 {
 	uint8_t msg[MAX_CEC_MSG_LEN];
 } __ec_align1;
 
+/* CEC message read from a CEC bus reported back to the AP */
+#define EC_CMD_CEC_READ_MSG 0x00B9
+
+/**
+ * struct ec_params_cec_read - Read a message from the CEC bus
+ * @port: CEC port to read a message on
+ */
+struct ec_params_cec_read {
+	uint8_t port;
+} __ec_align1;
+
+/**
+ * struct ec_response_cec_read - Message read from the CEC bus
+ * @msg_len: length of msg in bytes
+ * @msg: message content read from the CEC bus
+ */
+struct ec_response_cec_read {
+	uint8_t msg_len;
+	uint8_t msg[MAX_CEC_MSG_LEN];
+} __ec_align1;
+
 /* Set various CEC parameters */
 #define EC_CMD_CEC_SET 0x00BA
 
@@ -4529,6 +4550,8 @@ enum mkbp_cec_event {
 	EC_MKBP_CEC_SEND_OK			= BIT(0),
 	/* Outgoing message was not acknowledged */
 	EC_MKBP_CEC_SEND_FAILED			= BIT(1),
+	/* Incoming message can be read out by AP */
+	EC_MKBP_CEC_HAVE_DATA			= BIT(2),
 };
 
 /*****************************************************************************/