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 <[email protected]>

1 files changed, 22 insertions, 0 deletions

diff --git a/test/dm/core.c b/test/dm/core.c
index e0c5b9e0017..7371d3ff426 100644
--- a/test/dm/core.c
+++ b/test/dm/core.c
@@ -1351,3 +1351,25 @@ static int dm_test_dev_get_mem(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_dev_get_mem, UTF_SCAN_FDT);
+
+/* Test uclass_try_first_device() */
+static int dm_test_try_first_device(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+
+	/* Check that it doesn't create a device or uclass */
+	ut_assertnull(uclass_find(UCLASS_TEST));
+	ut_assertnull(uclass_try_first_device(UCLASS_TEST));
+	ut_assertnull(uclass_try_first_device(UCLASS_TEST));
+	ut_assertnull(uclass_find(UCLASS_TEST));
+
+	/* Create a test device */
+	ut_assertok(device_bind_by_name(uts->root, false, &driver_info_manual,
+					&dev));
+	dev = uclass_try_first_device(UCLASS_TEST);
+	ut_assertnonnull(dev);
+	ut_asserteq(UCLASS_TEST, device_get_uclass_id(dev));
+
+	return 0;
+}
+DM_TEST(dm_test_try_first_device, 0);