dm: core: Allow iterating devices without uclass_get()

At present we have uclass_foreach_dev() which requires that uclass_get()
be called beforehand to find the uclass. This is good if we suspect that
that function might fail, but often we know that the uclass is available.

Add a new helper which does this uclass_get() automatically, so that only
the uclass ID is needed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/include/dm/uclass.h b/include/dm/uclass.h
index 484d166013..74b8e2ecb5 100644
--- a/include/dm/uclass.h
+++ b/include/dm/uclass.h
@@ -366,6 +366,23 @@ int uclass_next_device_check(struct udevice **devp);
 int uclass_resolve_seq(struct udevice *dev);
 
 /**
+ * uclass_id_foreach_dev() - Helper function to iteration through devices
+ *
+ * This creates a for() loop which works through the available devices in
+ * a uclass ID in order from start to end.
+ *
+ * If for some reason the uclass cannot be found, this does nothing.
+ *
+ * @id: enum uclass_id ID to use
+ * @pos: struct udevice * to hold the current device. Set to NULL when there
+ * are no more devices.
+ * @uc: temporary uclass variable (struct udevice *)
+ */
+#define uclass_id_foreach_dev(id, pos, uc) \
+	if (!uclass_get(id, &uc)) \
+		list_for_each_entry(pos, &uc->dev_head, uclass_node)
+
+/**
  * uclass_foreach_dev() - Helper function to iteration through devices
  *
  * This creates a for() loop which works through the available devices in
diff --git a/test/dm/test-fdt.c b/test/dm/test-fdt.c
index d59c449ce0..8ea536c309 100644
--- a/test/dm/test-fdt.c
+++ b/test/dm/test-fdt.c
@@ -448,6 +448,27 @@ static int dm_test_first_next_device(struct unit_test_state *uts)
 }
 DM_TEST(dm_test_first_next_device, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
 
+/* Test iteration through devices in a uclass */
+static int dm_test_uclass_foreach(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct uclass *uc;
+	int count;
+
+	count = 0;
+	uclass_id_foreach_dev(UCLASS_TEST_FDT, dev, uc)
+		count++;
+	ut_asserteq(8, count);
+
+	count = 0;
+	uclass_foreach_dev(dev, uc)
+		count++;
+	ut_asserteq(8, count);
+
+	return 0;
+}
+DM_TEST(dm_test_uclass_foreach, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
 /**
  * check_devices() - Check return values and pointers
  *