mei: revamp writing slot counting

Since txe use doorbell and not circular buffer
we have to cheat in write slot counting, txe always consume all the
slots upon write. In order for it to work we need to track
slots using mei_hbuf_empty_slots() instead of tracking it in mei layer

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/amthif.c

@@ -436,23 +436,23 @@ unsigned int mei_amthif_poll(struct mei_device *dev,
 
 
 /**
- * mei_amthif_irq_write_completed - processes completed iamthif operation.
+ * mei_amthif_irq_write - write iamthif command in irq thread context.
  *
  * @dev: the device structure.
- * @slots: free slots.
  * @cb_pos: callback block.
  * @cl: private data of the file object.
  * @cmpl_list: complete list.
  *
  * returns 0, OK; otherwise, error.
  */
-int mei_amthif_irq_write_complete(struct mei_cl *cl, struct mei_cl_cb *cb,
-				  s32 *slots, struct mei_cl_cb *cmpl_list)
+int mei_amthif_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
+			 struct mei_cl_cb *cmpl_list)
 {
 	struct mei_device *dev = cl->dev;
 	struct mei_msg_hdr mei_hdr;
 	size_t len = dev->iamthif_msg_buf_size - dev->iamthif_msg_buf_index;
 	u32 msg_slots = mei_data2slots(len);
+	int slots;
 	int rets;
 
 	rets = mei_cl_flow_ctrl_creds(cl);
@@ -469,13 +469,15 @@ int mei_amthif_irq_write_complete(struct mei_cl *cl, struct mei_cl_cb *cb,
 	mei_hdr.reserved = 0;
 	mei_hdr.internal = 0;
 
-	if (*slots >= msg_slots) {
+	slots = mei_hbuf_empty_slots(dev);
+
+	if (slots >= msg_slots) {
 		mei_hdr.length = len;
 		mei_hdr.msg_complete = 1;
 	/* Split the message only if we can write the whole host buffer */
-	} else if (*slots == dev->hbuf_depth) {
-		msg_slots = *slots;
-		len = (*slots * sizeof(u32)) - sizeof(struct mei_msg_hdr);
+	} else if (slots == dev->hbuf_depth) {
+		msg_slots = slots;
+		len = (slots * sizeof(u32)) - sizeof(struct mei_msg_hdr);
 		mei_hdr.length = len;
 		mei_hdr.msg_complete = 0;
 	} else {
@@ -485,7 +487,6 @@ int mei_amthif_irq_write_complete(struct mei_cl *cl, struct mei_cl_cb *cb,
 
 	dev_dbg(&dev->pdev->dev, MEI_HDR_FMT,  MEI_HDR_PRM(&mei_hdr));
 
-	*slots -=  msg_slots;
 	rets = mei_write_message(dev, &mei_hdr,
 			dev->iamthif_msg_buf + dev->iamthif_msg_buf_index);
 	if (rets) {