dm: blk: Allow finding block devices without probing

Sometimes it is useful to be able to find a block device without also
probing it. Add a function for this as well as the associated test.

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

drivers/block/blk-uclass.c

@@ -363,7 +363,7 @@ int blk_next_device(struct udevice **devp)
 	} while (1);
 }
 
-int blk_get_device(int if_type, int devnum, struct udevice **devp)
+int blk_find_device(int if_type, int devnum, struct udevice **devp)
 {
 	struct uclass *uc;
 	struct udevice *dev;
@@ -379,13 +379,24 @@ int blk_get_device(int if_type, int devnum, struct udevice **devp)
 		      if_type, devnum, dev->name, desc->if_type, desc->devnum);
 		if (desc->if_type == if_type && desc->devnum == devnum) {
 			*devp = dev;
-			return device_probe(dev);
+			return 0;
 		}
 	}
 
 	return -ENODEV;
 }
 
+int blk_get_device(int if_type, int devnum, struct udevice **devp)
+{
+	int ret;
+
+	ret = blk_find_device(if_type, devnum, devp);
+	if (ret)
+		return ret;
+
+	return device_probe(*devp);
+}
+
 unsigned long blk_dread(struct blk_desc *block_dev, lbaint_t start,
 			lbaint_t blkcnt, void *buffer)
 {

include/blk.h

@@ -253,12 +253,25 @@ unsigned long blk_derase(struct blk_desc *block_dev, lbaint_t start,
 			 lbaint_t blkcnt);
 
 /**
+ * blk_find_device() - Find a block device
+ *
+ * This function does not activate the device. The device will be returned
+ * whether or not it is activated.
+ *
+ * @if_type:	Interface type (enum if_type_t)
+ * @devnum:	Device number (specific to each interface type)
+ * @devp:	the device, if found
+ * @return 0 if found, -ENODEV if no device found, or other -ve error value
+ */
+int blk_find_device(int if_type, int devnum, struct udevice **devp);
+
+/**
  * blk_get_device() - Find and probe a block device ready for use
  *
  * @if_type:	Interface type (enum if_type_t)
  * @devnum:	Device number (specific to each interface type)
  * @devp:	the device, if found
- * @return - if found, -ENODEV if no device found, or other -ve error value
+ * @return 0 if found, -ENODEV if no device found, or other -ve error value
  */
 int blk_get_device(int if_type, int devnum, struct udevice **devp);
 

test/dm/blk.c

@@ -94,3 +94,24 @@ static int dm_test_blk_usb(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_blk_usb, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that we can find block devices without probing them */
+static int dm_test_blk_find(struct unit_test_state *uts)
+{
+	struct udevice *blk, *dev;
+
+	ut_assertok(blk_create_device(gd->dm_root, "sandbox_host_blk", "test",
+				      IF_TYPE_HOST, 1, 512, 1024, &blk));
+	ut_asserteq(-ENODEV, blk_find_device(IF_TYPE_HOST, 0, &dev));
+	ut_assertok(blk_find_device(IF_TYPE_HOST, 1, &dev));
+	ut_asserteq_ptr(blk, dev);
+	ut_asserteq(false, device_active(dev));
+
+	/* Now activate it */
+	ut_assertok(blk_get_device(IF_TYPE_HOST, 1, &dev));
+	ut_asserteq_ptr(blk, dev);
+	ut_asserteq(true, device_active(dev));
+
+	return 0;
+}
+DM_TEST(dm_test_blk_find, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);