diff options
| -rw-r--r-- | include/fdtdec.h | 53 | ||||
| -rw-r--r-- | lib/fdtdec.c | 124 |
2 files changed, 177 insertions, 0 deletions
diff --git a/include/fdtdec.h b/include/fdtdec.h index 8c2bd21..8cf88dd 100644 --- a/include/fdtdec.h +++ b/include/fdtdec.h @@ -178,6 +178,59 @@ enum fdt_compat_id { COMPAT_COUNT, }; +#define MAX_PHANDLE_ARGS 16 +struct fdtdec_phandle_args { + int node; + int args_count; + uint32_t args[MAX_PHANDLE_ARGS]; +}; + +/** + * fdtdec_parse_phandle_with_args() - Find a node pointed by phandle in a list + * + * This function is useful to parse lists of phandles and their arguments. + * + * Example: + * + * phandle1: node1 { + * #list-cells = <2>; + * } + * + * phandle2: node2 { + * #list-cells = <1>; + * } + * + * node3 { + * list = <&phandle1 1 2 &phandle2 3>; + * } + * + * To get a device_node of the `node2' node you may call this: + * fdtdec_parse_phandle_with_args(blob, node3, "list", "#list-cells", 0, 1, + * &args); + * + * (This function is a modified version of __of_parse_phandle_with_args() from + * Linux 3.18) + * + * @blob: Pointer to device tree + * @src_node: Offset of device tree node containing a list + * @list_name: property name that contains a list + * @cells_name: property name that specifies the phandles' arguments count, + * or NULL to use @cells_count + * @cells_count: Cell count to use if @cells_name is NULL + * @index: index of a phandle to parse out + * @out_args: optional pointer to output arguments structure (will be filled) + * @return 0 on success (with @out_args filled out if not NULL), -ENOENT if + * @list_name does not exist, a phandle was not found, @cells_name + * could not be found, the arguments were truncated or there were too + * many arguments. + * + */ +int fdtdec_parse_phandle_with_args(const void *blob, int src_node, + const char *list_name, + const char *cells_name, + int cell_count, int index, + struct fdtdec_phandle_args *out_args); + /* GPIOs are numbered from 0 */ enum { FDT_GPIO_NONE = -1U, /* an invalid GPIO used to end our list */ diff --git a/lib/fdtdec.c b/lib/fdtdec.c index e989241..57e0edc 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -679,6 +679,130 @@ int fdtdec_get_bool(const void *blob, int node, const char *prop_name) return cell != NULL; } +int fdtdec_parse_phandle_with_args(const void *blob, int src_node, + const char *list_name, + const char *cells_name, + int cell_count, int index, + struct fdtdec_phandle_args *out_args) +{ + const __be32 *list, *list_end; + int rc = 0, size, cur_index = 0; + uint32_t count = 0; + int node = -1; + int phandle; + + /* Retrieve the phandle list property */ + list = fdt_getprop(blob, src_node, list_name, &size); + if (!list) + return -ENOENT; + list_end = list + size / sizeof(*list); + + /* Loop over the phandles until all the requested entry is found */ + while (list < list_end) { + rc = -EINVAL; + count = 0; + + /* + * If phandle is 0, then it is an empty entry with no + * arguments. Skip forward to the next entry. + */ + phandle = be32_to_cpup(list++); + if (phandle) { + /* + * Find the provider node and parse the #*-cells + * property to determine the argument length. + * + * This is not needed if the cell count is hard-coded + * (i.e. cells_name not set, but cell_count is set), + * except when we're going to return the found node + * below. + */ + if (cells_name || cur_index == index) { + node = fdt_node_offset_by_phandle(blob, + phandle); + if (!node) { + debug("%s: could not find phandle\n", + fdt_get_name(blob, src_node, + NULL)); + goto err; + } + } + + if (cells_name) { + count = fdtdec_get_int(blob, node, cells_name, + -1); + if (count == -1) { + debug("%s: could not get %s for %s\n", + fdt_get_name(blob, src_node, + NULL), + cells_name, + fdt_get_name(blob, node, + NULL)); + goto err; + } + } else { + count = cell_count; + } + + /* + * Make sure that the arguments actually fit in the + * remaining property data length + */ + if (list + count > list_end) { + debug("%s: arguments longer than property\n", + fdt_get_name(blob, src_node, NULL)); + goto err; + } + } + + /* + * All of the error cases above bail out of the loop, so at + * this point, the parsing is successful. If the requested + * index matches, then fill the out_args structure and return, + * or return -ENOENT for an empty entry. + */ + rc = -ENOENT; + if (cur_index == index) { + if (!phandle) + goto err; + + if (out_args) { + int i; + + if (count > MAX_PHANDLE_ARGS) { + debug("%s: too many arguments %d\n", + fdt_get_name(blob, src_node, + NULL), count); + count = MAX_PHANDLE_ARGS; + } + out_args->node = node; + out_args->args_count = count; + for (i = 0; i < count; i++) { + out_args->args[i] = + be32_to_cpup(list++); + } + } + + /* Found it! return success */ + return 0; + } + + node = -1; + list += count; + cur_index++; + } + + /* + * Result will be one of: + * -ENOENT : index is for empty phandle + * -EINVAL : parsing error on data + * [1..n] : Number of phandle (count mode; when index = -1) + */ + rc = index < 0 ? cur_index : -ENOENT; + err: + return rc; +} + /** * Decode a list of GPIOs from an FDT. This creates a list of GPIOs with no * terminating item. |