mei: add function to check write queues

The driver needs to check whether the write
queue idle before entering power gating
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/init.c

@@ -303,7 +303,28 @@ void mei_stop(struct mei_device *dev)
 }
 EXPORT_SYMBOL_GPL(mei_stop);
 
+/**
+ * mei_write_is_idle - check if the write queues are idle
+ *
+ * @dev: the device structure
+ *
+ * returns true of there is no pending write
+ */
+bool mei_write_is_idle(struct mei_device *dev)
+{
+	bool idle = (dev->dev_state == MEI_DEV_ENABLED &&
+		list_empty(&dev->ctrl_wr_list.list) &&
+		list_empty(&dev->write_list.list));
 
+	dev_dbg(&dev->pdev->dev, "write pg: is idle[%d] state=%s ctrl=%d write=%d\n",
+		idle,
+		mei_dev_state_str(dev->dev_state),
+		list_empty(&dev->ctrl_wr_list.list),
+		list_empty(&dev->write_list.list));
+
+	return idle;
+}
+EXPORT_SYMBOL_GPL(mei_write_is_idle);
 
 void mei_device_init(struct mei_device *dev)
 {

drivers/misc/mei/mei_dev.h

@@ -680,6 +680,8 @@ static inline int mei_count_full_read_slots(struct mei_device *dev)
 
 bool mei_hbuf_acquire(struct mei_device *dev);
 
+bool mei_write_is_idle(struct mei_device *dev);
+
 #if IS_ENABLED(CONFIG_DEBUG_FS)
 int mei_dbgfs_register(struct mei_device *dev, const char *name);
 void mei_dbgfs_deregister(struct mei_device *dev);