fdt: Add option to default to most compatible conf in a fit image
When booting a fit image with multiple configurations, the user either has to
specify which configuration to use explicitly, or there has to be a default
defined which is chosen automatically. This change adds an option to change
that behavior so that a configuration can be selected explicitly, or the
configuration which has the device tree that claims to be compatible with the
earliest item in U-Boot's device tree.
In other words, if U-Boot claimed to be compatible with A, B, and then C, and
the configurations claimed to be compatible with A, D and B, D and D, E, the
first configuration, A, D, would be chosen. Both the first and second
configurations match, but the first one matches a more specific entry in
U-Boot's device tree. The order in the kernel's device tree is ignored.
Signed-off-by: Gabe Black <gabeblack@google.com>
Commit-Ready: Gabe Black <gabeblack@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/image.c b/common/image.c
index df642e6..e93b6e8 100644
--- a/common/image.c
+++ b/common/image.c
@@ -3049,6 +3049,133 @@
return 1;
}
+
+/**
+ * fit_conf_find_compat
+ * @fit: pointer to the FIT format image header
+ * @fdt: pointer to the device tree to compare against
+ *
+ * fit_conf_find_compat() attempts to find the configuration whose fdt is the
+ * most compatible with the passed in device tree.
+ *
+ * Example:
+ *
+ * / o image-tree
+ * |-o images
+ * | |-o fdt@1
+ * | |-o fdt@2
+ * |
+ * |-o configurations
+ * |-o config@1
+ * | |-fdt = fdt@1
+ * |
+ * |-o config@2
+ * |-fdt = fdt@2
+ *
+ * / o U-Boot fdt
+ * |-compatible = "foo,bar", "bim,bam"
+ *
+ * / o kernel fdt1
+ * |-compatible = "foo,bar",
+ *
+ * / o kernel fdt2
+ * |-compatible = "bim,bam", "baz,biz"
+ *
+ * Configuration 1 would be picked because the first string in U-Boot's
+ * compatible list, "foo,bar", matches a compatible string in the root of fdt1.
+ * "bim,bam" in fdt2 matches the second string which isn't as good as fdt1.
+ *
+ * returns:
+ * offset to the configuration to use if one was found
+ * -1 otherwise
+ */
+int fit_conf_find_compat(const void *fit, const void *fdt)
+{
+ int ndepth = 0;
+ int noffset, confs_noffset, images_noffset;
+ const void *fdt_compat;
+ int fdt_compat_len;
+ int best_match_offset = 0;
+ int best_match_pos = 0;
+
+ confs_noffset = fdt_path_offset(fit, FIT_CONFS_PATH);
+ images_noffset = fdt_path_offset(fit, FIT_IMAGES_PATH);
+ if (confs_noffset < 0 || images_noffset < 0) {
+ debug("Can't find configurations or images nodes.\n");
+ return -1;
+ }
+
+ fdt_compat = fdt_getprop(fdt, 0, "compatible", &fdt_compat_len);
+ if (!fdt_compat) {
+ debug("Fdt for comparison has no \"compatible\" property.\n");
+ return -1;
+ }
+
+ /*
+ * Loop over the configurations in the FIT image.
+ */
+ for (noffset = fdt_next_node(fit, confs_noffset, &ndepth);
+ (noffset >= 0) && (ndepth > 0);
+ noffset = fdt_next_node(fit, noffset, &ndepth)) {
+ const void *kfdt;
+ const char *kfdt_name;
+ int kfdt_noffset;
+ const char *cur_fdt_compat;
+ int len;
+ size_t size;
+ int i;
+
+ if (ndepth > 1)
+ continue;
+
+ kfdt_name = fdt_getprop(fit, noffset, "fdt", &len);
+ if (!kfdt_name) {
+ debug("No fdt property found.\n");
+ continue;
+ }
+ kfdt_noffset = fdt_subnode_offset(fit, images_noffset,
+ kfdt_name);
+ if (kfdt_noffset < 0) {
+ debug("No image node named \"%s\" found.\n",
+ kfdt_name);
+ continue;
+ }
+ /*
+ * Get a pointer to this configuration's fdt.
+ */
+ if (fit_image_get_data(fit, kfdt_noffset, &kfdt, &size)) {
+ debug("Failed to get fdt \"%s\".\n", kfdt_name);
+ continue;
+ }
+
+ len = fdt_compat_len;
+ cur_fdt_compat = fdt_compat;
+ /*
+ * Look for a match for each U-Boot compatibility string in
+ * turn in this configuration's fdt.
+ */
+ for (i = 0; len > 0 &&
+ (!best_match_offset || best_match_pos > i); i++) {
+ int cur_len = strlen(cur_fdt_compat) + 1;
+
+ if (!fdt_node_check_compatible(kfdt, 0,
+ cur_fdt_compat)) {
+ best_match_offset = noffset;
+ best_match_pos = i;
+ break;
+ }
+ len -= cur_len;
+ cur_fdt_compat += cur_len;
+ }
+ }
+ if (!best_match_offset) {
+ debug("No match found.\n");
+ return -1;
+ }
+
+ return best_match_offset;
+}
+
/**
* fit_conf_get_node - get node offset for configuration of a given unit name
* @fit: pointer to the FIT format image header