core/i2c: Add request state tracking

Allow the submitter to track the state of an I2C request by adding
a state field to the request. This avoids the need to use a stub
completion callback in some cases.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

hw/p8-i2c.c

@@ -441,6 +441,7 @@ static void p8_i2c_complete_request(struct p8_i2c_master *master,
 	list_del(&req->link);
 	master->state = state_idle;
 	req->result = ret;
+	req->req_state = i2c_req_done;
 
 	/* Schedule re-enabling of sensor cache */
 	if (master->occ_cache_dis)

include/i2c.h

@@ -57,6 +57,12 @@ struct i2c_request {
 	uint32_t		offset;		/* Internal device offset */
 	uint32_t		rw_len;		/* Length of the data request */
 	void			*rw_buf;	/* Data request buffer */
+	enum i2c_request_state {
+		i2c_req_new,	/* un-initialised */
+		i2c_req_queued, /* waiting in the queue */
+		i2c_req_done,   /* request has been completed */
+	} req_state;
+
 	void			(*completion)(	/* Completion callback */
 					      int rc, struct i2c_request *req);
 	void			*user_data;	/* Client data */
@@ -68,9 +74,13 @@ struct i2c_request {
 extern void i2c_add_bus(struct i2c_bus *bus);
 extern struct i2c_bus *i2c_find_bus_by_id(uint32_t opal_id);
 
-static inline int i2c_queue_req(struct i2c_request *req)
+static inline int64_t i2c_queue_req(struct i2c_request *req)
 {
-	return req->bus->queue_req(req);
+	int64_t ret = req->bus->queue_req(req);
+
+	if (!ret)
+		req->req_state = i2c_req_queued;
+	return ret;
 }
 
 static inline uint64_t i2c_run_req(struct i2c_request *req)