dm: core: Add a function to see if a device exists

All the uclass functions for finding a device end up creating a uclass
if it doesn't exist. Add a function which instead returns NULL in this
case.

This is useful when in the 'unbind' path, since we don't want to undo
any unbinding which has already happened.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index 7ae0884a75e..f846a35d6b2 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -304,6 +304,17 @@ int uclass_find_device_by_name(enum uclass_id id, const char *name,
 	return uclass_find_device_by_namelen(id, name, strlen(name), devp);
 }
 
+struct udevice *uclass_try_first_device(enum uclass_id id)
+{
+	struct uclass *uc;
+
+	uc = uclass_find(id);
+	if (!uc || list_empty(&uc->dev_head))
+		return NULL;
+
+	return list_first_entry(&uc->dev_head, struct udevice, uclass_node);
+}
+
 int uclass_find_next_free_seq(struct uclass *uc)
 {
 	struct udevice *dev;