dm: syscon: Allow finding devices by driver data

We have a way to find a regmap by its syscon driver data value. Add the same
for syscon itself.

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

drivers/core/syscon-uclass.c

@@ -32,7 +32,7 @@ static int syscon_pre_probe(struct udevice *dev)
 	return regmap_init_mem(dev, &priv->regmap);
 }
 
-struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data)
+int syscon_get_by_driver_data(ulong driver_data, struct udevice **devp)
 {
 	struct udevice *dev;
 	struct uclass *uc;
@@ -40,22 +40,29 @@ struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data)
 
 	ret = uclass_get(UCLASS_SYSCON, &uc);
 	if (ret)
-		return ERR_PTR(ret);
+		return ret;
 	uclass_foreach_dev(dev, uc) {
 		if (dev->driver_data == driver_data) {
-			struct syscon_uc_info *priv;
-			int ret;
-
-			ret = device_probe(dev);
-			if (ret)
-				return ERR_PTR(ret);
-			priv = dev_get_uclass_priv(dev);
-
-			return priv->regmap;
+			*devp = dev;
+			return device_probe(dev);
 		}
 	}
 
-	return ERR_PTR(-ENODEV);
+	return -ENODEV;
+}
+
+struct regmap *syscon_get_regmap_by_driver_data(ulong driver_data)
+{
+	struct syscon_uc_info *priv;
+	struct udevice *dev;
+	int ret;
+
+	ret = syscon_get_by_driver_data(driver_data, &dev);
+	if (ret)
+		return ERR_PTR(ret);
+	priv = dev_get_uclass_priv(dev);
+
+	return priv->regmap;
 }
 
 void *syscon_get_first_range(ulong driver_data)

include/syscon.h

@@ -32,6 +32,20 @@ struct syscon_ops {
  */
 struct regmap *syscon_get_regmap(struct udevice *dev);
 
+/**
+ * syscon_get_regmap_by_driver_data() - Look up a controller by its ID
+ *
+ * Each system controller can be accessed by its driver data, which is
+ * assumed to be unique through the scope of all system controllers that
+ * are in use. This function looks up the controller given this driver data.
+ *
+ * @driver_data:	Driver data value to look up
+ * @devp:		Returns the controller correponding to @driver_data
+ * @return 0 on success, -ENODEV if the ID was not found, or other -ve error
+ *	   code
+ */
+int syscon_get_by_driver_data(ulong driver_data, struct udevice **devp);
+
 /**
  * syscon_get_regmap_by_driver_data() - Look up a controller by its ID
  *

test/dm/syscon.c

@@ -29,3 +29,20 @@ static int dm_test_syscon_base(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_syscon_base, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test system controller finding */
+static int dm_test_syscon_by_driver_data(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+
+	ut_assertok(syscon_get_by_driver_data(SYSCON0, &dev));
+	ut_asserteq(SYSCON0, dev->driver_data);
+
+	ut_assertok(syscon_get_by_driver_data(SYSCON1, &dev));
+	ut_asserteq(SYSCON1, dev->driver_data);
+
+	ut_asserteq(-ENODEV, syscon_get_by_driver_data(2, &dev));
+
+	return 0;
+}
+DM_TEST(dm_test_syscon_by_driver_data, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);