regmap: async: Add tracepoints for async I/O

Trace when we start and complete async writes, and when we start and
finish blocking for their completion. This is useful for performance
analysis of the resulting I/O patterns.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 3d23675..7c6d3be 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -999,6 +999,8 @@
 		if (!async)
 			return -ENOMEM;
 
+		trace_regmap_async_write_start(map->dev, reg, val_len);
+
 		async->work_buf = kzalloc(map->format.buf_size,
 					  GFP_KERNEL | GFP_DMA);
 		if (!async->work_buf) {
@@ -1640,6 +1642,8 @@
 	struct regmap *map = async->map;
 	bool wake;
 
+	trace_regmap_async_io_complete(map->dev);
+
 	spin_lock(&map->async_lock);
 
 	list_del(&async->list);
@@ -1686,6 +1690,8 @@
 	if (!map->bus->async_write)
 		return 0;
 
+	trace_regmap_async_complete_start(map->dev);
+
 	wait_event(map->async_waitq, regmap_async_is_done(map));
 
 	spin_lock_irqsave(&map->async_lock, flags);
@@ -1693,6 +1699,8 @@
 	map->async_ret = 0;
 	spin_unlock_irqrestore(&map->async_lock, flags);
 
+	trace_regmap_async_complete_done(map->dev);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(regmap_async_complete);