clk: Allow clk_get_by_name() with NULL name

This allows devm_clock_get(dev, NULL) to work and get the first clock,
which is common in code ported from Linux.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20230122000252.53642-1-samuel@sholland.org

3 files changed, 14 insertions, 7 deletions

diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
index 2f9635524c..dc3e9d6a26 100644
--- a/drivers/clk/clk-uclass.c
+++ b/drivers/clk/clk-uclass.c
@@ -399,16 +399,18 @@ int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk)
 
 int clk_get_by_name_nodev(ofnode node, const char *name, struct clk *clk)
 {
-	int index;
+	int index = 0;
 
 	debug("%s(node=%p, name=%s, clk=%p)\n", __func__,
 		ofnode_get_name(node), name, clk);
 	clk->dev = NULL;
 
-	index = ofnode_stringlist_search(node, "clock-names", name);
-	if (index < 0) {
-		debug("fdt_stringlist_search() failed: %d\n", index);
-		return index;
+	if (name) {
+		index = ofnode_stringlist_search(node, "clock-names", name);
+		if (index < 0) {
+			debug("fdt_stringlist_search() failed: %d\n", index);
+			return index;
+		}
 	}
 
 	return clk_get_by_index_nodev(node, index, clk);
diff --git a/include/clk.h b/include/clk.h
index 138766bd49..d91285235f 100644
--- a/include/clk.h
+++ b/include/clk.h
@@ -167,7 +167,7 @@ int clk_get_bulk(struct udevice *dev, struct clk_bulk *bulk);
  * clk_get_by_name() - Get/request a clock by name.
  * @dev:	The client device.
  * @name:	The name of the clock to request, within the client's list of
- *		clocks.
+ *		clocks, or NULL to request the first clock in the list.
  * @clk:	A pointer to a clock struct to initialize.
  *
  * This looks up and requests a clock. The name is relative to the client
@@ -184,7 +184,7 @@ int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
  * clk_get_by_name_nodev - Get/request a clock by name without a device.
  * @node:	The client ofnode.
  * @name:	The name of the clock to request, within the client's list of
- *		clocks.
+ *		clocks, or NULL to request the first clock in the list.
  * @clk:	A pointer to a clock struct to initialize.
  *
  * Return: 0 if OK, or a negative error code.
diff --git a/test/dm/clk.c b/test/dm/clk.c
index 21997ed892..f48de05436 100644
--- a/test/dm/clk.c
+++ b/test/dm/clk.c
@@ -26,6 +26,11 @@ static int dm_test_clk_base(struct unit_test_state *uts)
 	ut_assertok(uclass_get_device_by_name(UCLASS_MISC, "clk-test", &dev));
 
 	/* Get the same clk port in 2 different ways and compare */
+	ut_assertok(clk_get_by_index(dev, 0, &clk_method1));
+	ut_assertok(clk_get_by_name(dev, NULL, &clk_method2));
+	ut_asserteq(clk_is_match(&clk_method1, &clk_method2), true);
+	ut_asserteq(clk_method1.id, clk_method2.id);
+
 	ut_assertok(clk_get_by_index(dev, 1, &clk_method1));
 	ut_assertok(clk_get_by_index_nodev(dev_ofnode(dev), 1, &clk_method2));
 	ut_asserteq(clk_is_match(&clk_method1, &clk_method2), true);