[coreboot-gerrit] Change in coreboot[master]: device: Add find_dev_nested_path helper function

[Rob Barnes (Code Review)]

Rob Barnes has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/43776 )

Change subject: device: Add find_dev_nested_path helper function
......................................................................

device: Add find_dev_nested_path helper function

Add find_dev_nested_path helper function to simplify finding deeply
nested devices.

BUG=b:157580724
TEST=Find bluetooth device on dalboz

Change-Id: I48fa5fcad0030fb6dcea97b9fc76e1d3d3f9b28f
---
M src/device/device_const.c
M src/include/device/device.h
2 files changed, 32 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/76/43776/1

diff --git a/src/device/device_const.c b/src/device/device_const.c
index 12d5386..765fcdc 100644
--- a/src/device/device_const.c
+++ b/src/device/device_const.c
@@ -196,6 +196,34 @@
    return child;
 }

+/**
+ * Find the device structure given an array of nested device paths,
+ *
+ * @param parent The parent bus to start the search on.
+ * @param nested_path An array of relative paths from the parent bus to
+ 	  the target device.
+ * @param nested_path_length Number of path elements in nested_path array.
+ * @return Pointer to a device structure for the device at nested path
+ *         or 0/NULL if no device is found.
+ */
+DEVTREE_CONST struct device *find_dev_nested_path(
+	const struct bus *parent, const struct device_path nested_path[],
+	unsigned int nested_path_length)
+{
+	DEVTREE_CONST struct device *child;
+
+	if (!parent || !nested_path_length)
+		return NULL;
+
+	child = find_dev_path(parent, nested_path);
+
+	/* Terminate recursion at end of nested path or child not found */
+	if(nested_path_length == 1 || !child)
+		return child;
+
+	return find_dev_nested_path(child->link_list, nested_path+1, nested_path_length-1);
+}
+
 DEVTREE_CONST struct device *pcidev_path_behind(
    const struct bus *parent, pci_devfn_t devfn)
 {
diff --git a/src/include/device/device.h b/src/include/device/device.h
index 082dcbb..202d3ae 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -202,6 +202,10 @@
 DEVTREE_CONST struct device *find_dev_path(
    	const struct bus *parent,
    	const struct device_path *path);
+DEVTREE_CONST struct device *find_dev_nested_path(
+		const struct bus *parent,
+		const struct device_path nested_path[],
+		unsigned int nested_path_length);
 struct device *alloc_find_dev(struct bus *parent, struct device_path *path);
 struct device *dev_find_device(u16 vendor, u16 device, struct device *from);
 struct device *dev_find_class(unsigned int class, struct device *from);