host_command: Add send_result() to the arg structure

It's a bit odd that the drivers package up a command to be processed
by host_command, but then host_command calls a global function to
pass the response back.

This adds ambiguity in the host_send_response() implementations as to
whether the command being responded to really is using the same
buffers that the driver set up.

Add a function pointer to the command, and have host_command call
that. Add status to the args structure also, which removes some of
the special case logic for error handling.

BUG=chrome-os-partner:11317
TEST=manual and a bit ad-hoc:
(note, this testing is not completed yet)
Check that snow and link still process commands correctly over I2C
from U-Boot. At this stage only the old interface is supported.
SMDK5250 # mkbp test
Old interface:

New interface:
Version 0: ec_command() returned error
Test failed with error -1
SMDK5250 #

Change-Id: I816738150bce3f8d78e7cd32abf361621aa12312
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/28154
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 18 insertions, 11 deletions

diff --git a/include/host_command.h b/include/host_command.h
index 65cf849c6a..a88761a6e2 100644
--- a/include/host_command.h
+++ b/include/host_command.h
@@ -13,10 +13,16 @@
 
 /* Args for host command handler */
 struct host_cmd_handler_args {
+	/*
+	 * The driver that receives the command sets up the send_response()
+	 * handler. Once the command is processed this handler is called to
+	 * send the response back to the host.
+	 */
+	void (*send_response)(struct host_cmd_handler_args *args);
 	uint8_t command;       /* Command (e.g., EC_CMD_FLASH_GET_INFO) */
 	uint8_t version;       /* Version of command (0-31) */
-	const uint8_t *params; /* Input parameters */
 	uint8_t params_size;   /* Size of input parameters in bytes */
+	const uint8_t *params; /* Input parameters */
 	/*
 	 * Pointer to output response data buffer.  On input to the handler,
 	 * points to a buffer of size response_max.  Command handler can change
@@ -31,6 +37,17 @@ struct host_cmd_handler_args {
 	 */
 	uint8_t response_max;
 	uint8_t response_size; /* Size of data pointed to by resp_ptr */
+
+	/*
+	 * This is the result returned by command and therefore the status to
+	 * be reported from the command execution to the host. The driver
+	 * should set this to EC_RES_SUCCESS on receipt of a valid command.
+	 * It is then passed back to the driver via send_response() when
+	 * command execution is complete. The driver may still override this
+	 * when sending the response back to the host if it detects an error
+	 * in the response or in its own operation.
+	 */
+	enum ec_status result;
 };
 
 /* Host command */
@@ -100,16 +117,6 @@ uint32_t host_get_events(void);
  */
 void host_command_received(struct host_cmd_handler_args *args);
 
-/**
- * Send a successful result code to a host command.
- *
- * Response data, if any, has been stored in the args passed to
- * host_command_received().
- *
- * @param result        Result code for the command (EC_RES_...)
- */
-void host_send_response(enum ec_status result);
-
 /* Register a host command handler */
 #define DECLARE_HOST_COMMAND(command, routine, version_mask)		\
 	const struct host_command __host_cmd_##command			\