[U-Boot] [PATCH v2 02/12] dm: device: add function device_get_first_child_by_uclass_id()

[Przemyslaw Marczak]

To implement functionality for devices connected by some external
interface, sometimes there is need to implement more then one,
and different uclass type drivers.

But only one i2c/spi dm chip can exists, per each bus i2c address
or spi select. Then, it seems to be useful, to get the child device
by uclass type, for the parent with known chip address.

So, this change will be useful for the pmic case:
|- i2c bus
  '- pmic i2c chip (parent)
    '- uclass regulator (child 1)
    '- uclass charger (child 2)

This will allow to get the regulator or charger device if knows only parent
i2c/spi address.

Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>
---
Changes V2:
- new commit
---
 drivers/core/device.c | 15 +++++++++++++++
 include/dm/device.h   | 16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/core/device.c b/drivers/core/device.c
index 73c3e07..76b22cf 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -397,6 +397,21 @@ int device_find_child_by_of_offset(struct udevice *parent, int of_offset,
 	return -ENODEV;
 }
 
+int device_get_first_child_by_uclass_id(struct udevice *parent, int uclass_id,
+					struct udevice **devp)
+{
+	struct udevice *dev;
+
+	*devp = NULL;
+
+	list_for_each_entry(dev, &parent->child_head, sibling_node) {
+		if (dev->driver->id == uclass_id)
+			return device_get_device_tail(dev, 0, devp);
+	}
+
+	return -ENODEV;
+}
+
 int device_get_child_by_of_offset(struct udevice *parent, int seq,
 				  struct udevice **devp)
 {
diff --git a/include/dm/device.h b/include/dm/device.h
index 7a48eb8..9f0d6ce 100644
--- a/include/dm/device.h
+++ b/include/dm/device.h
@@ -335,6 +335,22 @@ int device_get_child_by_of_offset(struct udevice *parent, int seq,
 				  struct udevice **devp);
 
 /**
+ * device_get_first_child_by_uclass_id() - Get the first child device based
+ *                                         on UCLASS_ID
+ *
+ * Locates a child device by its uclass id.
+ *
+ * The device is probed to activate it ready for use.
+ *
+ * @parent: Parent device
+ * @uclass_id: child uclass id
+ * @devp: Returns pointer to device if found, otherwise this is set to NULL
+ * @return 0 if OK, -ve on error
+ */
+int device_get_first_child_by_uclass_id(struct udevice *parent, int uclass_id,
+					struct udevice **devp);
+
+/**
  * device_find_first_child() - Find the first child of a device
  *
  * @parent: Parent device to search
-- 
1.9.1