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 <sjg@chromium.org>
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 @@
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.