From 57068a7aeb19fee06933986926eaea3cf0128f16 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Mon, 5 Jan 2015 20:05:26 -0700 Subject: dm: fdt: Add a function to decode phandles with arguments For GPIOs and other functions we want to look up a phandle and then decode a list of arguments for that phandle. Each phandle can have a different number of arguments, specified by a property in the target node. This is the "#gpio-cells" property for GPIOs. Add a function to provide this feature, taken modified from Linux 3.18. Signed-off-by: Simon Glass --- lib/fdtdec.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) (limited to 'lib') diff --git a/lib/fdtdec.c b/lib/fdtdec.c index e989241b70..57e0edca99 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. -- cgit v1.2.1