diff options
| -rw-r--r-- | drivers/of/fdt.c | 76 | ||||
| -rw-r--r-- | include/linux/of_fdt.h | 3 |
2 files changed, 79 insertions, 0 deletions
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 6bb7cf2de55..585b1a67cfb 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -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 diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h index ed136ad698c..19f26f8d220 100644 --- a/include/linux/of_fdt.h +++ b/include/linux/of_fdt.h @@ -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); |