dm: blk: Add a way to obtain a block device from its parent
Many devices support a child block device (e.g. MMC, USB). Add a
convenient way to get this device given the parent device.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
index 6145675..23f131b 100644
--- a/drivers/block/blk-uclass.c
+++ b/drivers/block/blk-uclass.c
@@ -453,6 +453,32 @@
return 0;
}
+int blk_get_from_parent(struct udevice *parent, struct udevice **devp)
+{
+ struct udevice *dev;
+ enum uclass_id id;
+ int ret;
+
+ device_find_first_child(parent, &dev);
+ if (!dev) {
+ debug("%s: No block device found for parent '%s'\n", __func__,
+ parent->name);
+ return -ENODEV;
+ }
+ id = device_get_uclass_id(dev);
+ if (id != UCLASS_BLK) {
+ debug("%s: Incorrect uclass %s for block device '%s'\n",
+ __func__, uclass_get_name(id), dev->name);
+ return -ENOTBLK;
+ }
+ ret = device_probe(dev);
+ if (ret)
+ return ret;
+ *devp = dev;
+
+ return 0;
+}
+
int blk_find_max_devnum(enum if_type if_type)
{
struct udevice *dev;
diff --git a/include/blk.h b/include/blk.h
index a128ee4..4d60987 100644
--- a/include/blk.h
+++ b/include/blk.h
@@ -616,4 +616,11 @@
*/
int blk_select_hwpart_devnum(enum if_type if_type, int devnum, int hwpart);
+/**
+ * blk_get_from_parent() - obtain a block device by looking up its parent
+ *
+ * All devices with
+ */
+int blk_get_from_parent(struct udevice *parent, struct udevice **devp);
+
#endif
diff --git a/test/dm/blk.c b/test/dm/blk.c
index 5c5eb82..923e8d9 100644
--- a/test/dm/blk.c
+++ b/test/dm/blk.c
@@ -150,3 +150,21 @@
return 0;
}
DM_TEST(dm_test_blk_devnum, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that we can get a block from its parent */
+static int dm_test_blk_get_from_parent(struct unit_test_state *uts)
+{
+ struct udevice *dev, *blk;
+
+ ut_assertok(uclass_get_device(UCLASS_MMC, 0, &dev));
+ ut_assertok(blk_get_from_parent(dev, &blk));
+
+ ut_assertok(uclass_get_device(UCLASS_I2C, 0, &dev));
+ ut_asserteq(-ENOTBLK, blk_get_from_parent(dev, &blk));
+
+ ut_assertok(uclass_get_device(UCLASS_GPIO, 0, &dev));
+ ut_asserteq(-ENODEV, blk_get_from_parent(dev, &blk));
+
+ return 0;
+}
+DM_TEST(dm_test_blk_get_from_parent, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);