drivers: of: add function to scan fdt nodes given by path (57d74bcf) · Commits · 戴 / test

drivers/of/fdt.c

+76 −0

Original line number	Diff line number	Diff line
		@@ -543,6 +543,82 @@ int __init of_flat_dt_match(unsigned long node, const char const compat)
		return of_fdt_match(initial_boot_params, node, compat);
		}

		struct fdt_scan_status {
		const char *name;
		int namelen;
		int depth;
		int found;
		int (iterator)(unsigned long node, const char uname, int depth, void *data);
		void *data;
		};

		/**
		* fdt_scan_node_by_path - iterator for of_scan_flat_dt_by_path function
		*/
		static int __init fdt_scan_node_by_path(unsigned long node, const char *uname,
		int depth, void *data)
		{
		struct fdt_scan_status *st = data;

		/*
		* if scan at the requested fdt node has been completed,
		* return -ENXIO to abort further scanning
		*/
		if (depth <= st->depth)
		return -ENXIO;

		/* requested fdt node has been found, so call iterator function */
		if (st->found)
		return st->iterator(node, uname, depth, st->data);

		/* check if scanning automata is entering next level of fdt nodes */
		if (depth == st->depth + 1 &&
		strncmp(st->name, uname, st->namelen) == 0 &&
		uname[st->namelen] == 0) {
		st->depth += 1;
		if (st->name[st->namelen] == 0) {
		st->found = 1;
		} else {
		const char *next = st->name + st->namelen + 1;
		st->name = next;
		st->namelen = strcspn(next, "/");
		}
		return 0;
		}

		/* scan next fdt node */
		return 0;
		}

		/**
		* of_scan_flat_dt_by_path - scan flattened tree blob and call callback on each
		* child of the given path.
		* @path: path to start searching for children
		* @it: callback function
		* @data: context data pointer
		*
		* This function is used to scan the flattened device-tree starting from the
		* node given by path. It is used to extract information (like reserved
		* memory), which is required on ealy boot before we can unflatten the tree.
		*/
		int __init of_scan_flat_dt_by_path(const char *path,
		int (it)(unsigned long node, const char name, int depth, void *data),
		void *data)
		{
		struct fdt_scan_status st = {path, 0, -1, 0, it, data};
		int ret = 0;

		if (initial_boot_params)
		ret = of_scan_flat_dt(fdt_scan_node_by_path, &st);

		if (!st.found)
		return -ENOENT;
		else if (ret == -ENXIO) /* scan has been completed */
		return 0;
		else
		return ret;
		}

		#ifdef CONFIG_BLK_DEV_INITRD
		/**
		* early_init_dt_check_for_initrd - Decode initrd location from flat tree

include/linux/of_fdt.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -90,6 +90,9 @@ extern void of_get_flat_dt_prop(unsigned long node, const char name,
		extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
		extern int of_flat_dt_match(unsigned long node, const char const matches);
		extern unsigned long of_get_flat_dt_root(void);
		extern int of_scan_flat_dt_by_path(const char *path,
		int (it)(unsigned long node, const char name, int depth, void *data),
		void *data);

		extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
		int depth, void *data);

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