block: Add a function to find block device descriptor

Add a function to find the block device descriptor of the parent
device.

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>
[trini: Move function declaration to avoid warning]
Signed-off-by: Tom Rini <trini@konsulko.com>

drivers/block/blk-uclass.c

@@ -131,6 +131,29 @@ struct blk_desc *blk_get_devnum_by_typename(const char *if_typename, int devnum)
 	return NULL;
 }
 
+/**
+ * blk_get_by_device() - Get the block device descriptor for the given device
+ * @dev:	Instance of a storage device
+ *
+ * Return: With block device descriptor on success , NULL if there is no such
+ *	   block device.
+ */
+struct blk_desc *blk_get_by_device(struct udevice *dev)
+{
+	struct udevice *child_dev, *next;
+
+	device_foreach_child_safe(child_dev, next, dev) {
+		if (device_get_uclass_id(child_dev) != UCLASS_BLK)
+			continue;
+
+		return dev_get_uclass_platdata(child_dev);
+	}
+
+	debug("%s: No block device found\n", __func__);
+
+	return NULL;
+}
+
 /**
  * get_desc() - Get the block device descriptor for the given device number
  *

include/blk.h

@@ -406,6 +406,15 @@ int blk_select_hwpart(struct udevice *dev, int hwpart);
  */
 int blk_get_from_parent(struct udevice *parent, struct udevice **devp);
 
+/**
+ * blk_get_by_device() - Get the block device descriptor for the given device
+ * @dev:	Instance of a storage device
+ *
+ * Return: With block device descriptor on success , NULL if there is no such
+ *	   block device.
+ */
+struct blk_desc *blk_get_by_device(struct udevice *dev);
+
 #else
 #include <errno.h>
 /*