[U-Boot] [PATCH v3 3/4] core: Add dev_{disable,enable}_by_path

[Mario Six]

We cannot use device structures to disable devices, since getting
them with the API functions would bind and activate the device, which
would fail if the underlying device does not exist.

---

Hence, add a function to disable devices by path in a live device tree.

Signed-off-by: Mario Six <mario.six at gdsys.cc>

v2 -> v3:
* Renamed res to ret
* Introduced device_find_by_ofnode() function
* Fixed error handling in some places

v1 -> v2:
* Simplified np_to_ofnode(of_find_node_by_path(path)) to ofnode_path(path)
* Switched to returning -ENOSYS if livetree is not enabled

---
 drivers/core/device.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/dm/device.h   | 16 +++++++++++
 2 files changed, 94 insertions(+)

diff --git a/drivers/core/device.c b/drivers/core/device.c
index e048e1a6595..c0037a2eeaf 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -501,6 +501,33 @@ static int device_get_device_tail(struct udevice *dev, int ret,
 	return 0;
 }

+/**
+ * device_find_by_ofnode() - Return device associated with given ofnode
+ *
+ * The returned device is *not* activated.
+ *
+ * @node: The ofnode for which a associated device should be looked up
+ * @devp: Pointer to structure to hold the found device
+ * Return: 0 if OK, -ve on error
+ */
+static int device_find_by_ofnode(ofnode node, struct udevice **devp)
+{
+	struct uclass *uc;
+	struct udevice *dev;
+	int ret;
+
+	list_for_each_entry(uc, &gd->uclass_root, sibling_node) {
+		ret = uclass_find_device_by_ofnode(uc->uc_drv->id, node,
+						   &dev);
+		if (!ret || dev) {
+			*devp = dev;
+			return 0;
+		}
+	}
+
+	return -ENODEV;
+}
+
 int device_get_child(struct udevice *parent, int index, struct udevice **devp)
 {
 	struct udevice *dev;
@@ -717,3 +744,54 @@ bool of_machine_is_compatible(const char *compat)

 	return !fdt_node_check_compatible(fdt, 0, compat);
 }
+
+int dev_disable_by_path(const char *path)
+{
+	struct uclass *uc;
+	ofnode node = ofnode_path(path);
+	struct udevice *dev;
+	int ret = 1;
+
+	if (!of_live_active())
+		return -ENOSYS;
+
+	list_for_each_entry(uc, &gd->uclass_root, sibling_node) {
+		ret = uclass_find_device_by_ofnode(uc->uc_drv->id, node, &dev);
+		if (!ret)
+			break;
+	}
+
+	if (ret)
+		return ret;
+
+	ret = device_remove(dev, DM_REMOVE_NORMAL);
+	if (ret)
+		return ret;
+
+	ret = device_unbind(dev);
+	if (ret)
+		return ret;
+
+	return ofnode_set_enabled(node, false);
+}
+
+int dev_enable_by_path(const char *path)
+{
+	ofnode node = ofnode_path(path);
+	ofnode pnode = ofnode_get_parent(node);
+	struct udevice *parent;
+	int ret = 1;
+
+	if (!of_live_active())
+		return -ENOSYS;
+
+	ret = device_find_by_ofnode(pnode, &parent);
+	if (ret)
+		return ret;
+
+	ret = ofnode_set_enabled(node, true);
+	if (ret)
+		return ret;
+
+	return lists_bind_fdt(parent, node, NULL);
+}
diff --git a/include/dm/device.h b/include/dm/device.h
index 49078bc6b36..7d569f91979 100644
--- a/include/dm/device.h
+++ b/include/dm/device.h
@@ -586,6 +586,22 @@ bool device_is_compatible(struct udevice *dev, const char *compat);
 bool of_machine_is_compatible(const char *compat);

 /**
+ * dev_disable_by_path() - Disable a device given its device tree path
+ *
+ * @path:	The device tree path identifying the device to be disabled
+ * @return 0 on success, -ve on error
+ */
+int dev_disable_by_path(const char *path);
+
+/**
+ * dev_enable_by_path() - Enable a device given its device tree path
+ *
+ * @path:	The device tree path identifying the device to be enabled
+ * @return 0 on success, -ve on error
+ */
+int dev_enable_by_path(const char *path);
+
+/**
  * device_is_on_pci_bus - Test if a device is on a PCI bus
  *
  * @dev:	device to test
--
2.11.0