This patch enables an overlay to refer to a previous overlay's labels by performing a merge of symbol information at application time.
In a nutshell it allows an overlay to refer to a symbol that a previous overlay has defined. It requires both the base and all the overlays to be compiled with the -@ command line switch so that symbol information is included.
base.dts --------
/dts-v1/; / { foo: foonode { foo-property; }; };
$ dtc -@ -I dts -O dtb -o base.dtb base.dts
bar.dts -------
/dts-v1/; /plugin/; / { fragment@1 { target = <&foo>; __overlay__ { overlay-1-property; bar: barnode { bar-property; }; }; }; };
$ dtc -@ -I dts -O dtb -o bar.dtb bar.dts
baz.dts -------
/dts-v1/; /plugin/; / { fragment@1 { target = <&bar>; __overlay__ { overlay-2-property; baz: baznode { baz-property; }; }; }; };
$ dtc -@ -I dts -O dtb -o baz.dtb baz.dts
Applying the overlays:
$ fdtoverlay -i base.dtb -o target.dtb bar.dtb baz.dtb
Dumping:
$ fdtdump target.dtb / { foonode { overlay-1-property; foo-property; linux,phandle = <0x00000001>; phandle = <0x00000001>; barnode { overlay-2-property; phandle = <0x00000002>; linux,phandle = <0x00000002>; bar-property; baznode { phandle = <0x00000003>; linux,phandle = <0x00000003>; baz-property; }; }; }; __symbols__ { baz = "/foonode/barnode/baznode"; bar = "/foonode/barnode"; foo = "/foonode"; }; };
Signed-off-by: Pantelis Antoniou pantelis.antoniou@konsulko.com Signed-off-by: David Gibson david@gibson.dropbear.id.au --- lib/libfdt/fdt_overlay.c | 228 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 206 insertions(+), 22 deletions(-)
diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c index ceb9687..bd81241 100644 --- a/lib/libfdt/fdt_overlay.c +++ b/lib/libfdt/fdt_overlay.c @@ -39,6 +39,7 @@ static uint32_t overlay_get_target_phandle(const void *fdto, int fragment) * @fdt: Base device tree blob * @fdto: Device tree overlay blob * @fragment: node offset of the fragment in the overlay + * @pathp: pointer which receives the path of the target (or NULL) * * overlay_get_target() retrieves the target offset in the base * device tree of a fragment, no matter how the actual targetting is @@ -49,37 +50,47 @@ static uint32_t overlay_get_target_phandle(const void *fdto, int fragment) * Negative error code on error */ static int overlay_get_target(const void *fdt, const void *fdto, - int fragment) + int fragment, char const **pathp) { uint32_t phandle; - const char *path; - int path_len; + const char *path = NULL; + int path_len = 0, ret;
/* Try first to do a phandle based lookup */ phandle = overlay_get_target_phandle(fdto, fragment); if (phandle == (uint32_t)-1) return -FDT_ERR_BADPHANDLE;
- if (phandle) - return fdt_node_offset_by_phandle(fdt, phandle); + /* no phandle, try path */ + if (!phandle) { + /* And then a path based lookup */ + path = fdt_getprop(fdto, fragment, "target-path", &path_len); + if (path) + ret = fdt_path_offset(fdt, path); + else + ret = path_len; + } else + ret = fdt_node_offset_by_phandle(fdt, phandle);
- /* And then a path based lookup */ - path = fdt_getprop(fdto, fragment, "target-path", &path_len); - if (!path) { - /* - * If we haven't found either a target or a - * target-path property in a node that contains a - * __overlay__ subnode (we wouldn't be called - * otherwise), consider it a improperly written - * overlay - */ - if (path_len == -FDT_ERR_NOTFOUND) - return -FDT_ERR_BADOVERLAY; + /* + * If we haven't found either a target or a + * target-path property in a node that contains a + * __overlay__ subnode (we wouldn't be called + * otherwise), consider it a improperly written + * overlay + */ + if (ret < 0 && path_len == -FDT_ERR_NOTFOUND) + ret = -FDT_ERR_BADOVERLAY; + + /* return on error */ + if (ret < 0) + return ret;
- return path_len; - } + /* return pointer to path (if available) */ + if (pathp) + *pathp = path ? path : NULL;
- return fdt_path_offset(fdt, path); + return ret; }
/** @@ -590,7 +601,7 @@ static int overlay_apply_node(void *fdt, int target, * * overlay_merge() merges an overlay into its base device tree. * - * This is the final step in the device tree overlay application + * This is the next to last step in the device tree overlay application * process, when all the phandles have been adjusted and resolved and * you just have to merge overlay into the base device tree. * @@ -618,7 +629,7 @@ static int overlay_merge(void *fdt, void *fdto) if (overlay < 0) return overlay;
- target = overlay_get_target(fdt, fdto, fragment); + target = overlay_get_target(fdt, fdto, fragment, NULL); if (target < 0) return target;
@@ -630,6 +641,175 @@ static int overlay_merge(void *fdt, void *fdto) return 0; }
+static int get_path_len(const void *fdt, int nodeoffset) +{ + int len = 0, namelen; + const char *name; + + FDT_CHECK_HEADER(fdt); + + for (;;) { + name = fdt_get_name(fdt, nodeoffset, &namelen); + if (!name) + return namelen; + + /* root? we're done */ + if (namelen == 0) + break; + + nodeoffset = fdt_parent_offset(fdt, nodeoffset); + if (nodeoffset < 0) + return nodeoffset; + len += namelen + 1; + } + + /* in case of root pretend it's "/" */ + if (len == 0) + len++; + return len; +} + +/** + * overlay_symbol_update - Update the symbols of base tree after a merge + * @fdt: Base Device Tree blob + * @fdto: Device tree overlay blob + * + * overlay_symbol_update() updates the symbols of the base tree with the + * symbols of the applied overlay + * + * This is the last step in the device tree overlay application + * process, allowing the reference of overlay symbols by subsequent + * overlay operations. + * + * returns: + * 0 on success + * Negative error code on failure + */ +static int overlay_symbol_update(void *fdt, void *fdto) +{ + int root_sym, ov_sym, prop, path_len, fragment, target; + int len, frag_name_len, ret, rel_path_len; + const char *s, *e; + const char *path; + const char *name; + const char *frag_name; + const char *rel_path; + const char *target_path; + char *buf; + void *p; + + ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__"); + + /* if no overlay symbols exist no problem */ + if (ov_sym < 0) + return 0; + + root_sym = fdt_subnode_offset(fdt, 0, "__symbols__"); + + /* it no root symbols exist we should create them */ + if (root_sym == -FDT_ERR_NOTFOUND) + root_sym = fdt_add_subnode(fdt, 0, "__symbols__"); + + /* any error is fatal now */ + if (root_sym < 0) + return root_sym; + + /* iterate over each overlay symbol */ + fdt_for_each_property_offset(prop, fdto, ov_sym) { + path = fdt_getprop_by_offset(fdto, prop, &name, &path_len); + if (!path) + return path_len; + + /* verify it's a string property (terminated by a single \0) */ + if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1]) + return -FDT_ERR_BADVALUE; + + /* keep end marker to avoid strlen() */ + e = path + path_len; + + /* format: /<fragment-name>/__overlay__/<relative-subnode-path> */ + + if (*path != '/') + return -FDT_ERR_BADVALUE; + + /* get fragment name first */ + s = strchr(path + 1, '/'); + if (!s) + return -FDT_ERR_BADOVERLAY; + + frag_name = path + 1; + frag_name_len = s - path - 1; + + /* verify format; safe since "s" lies in \0 terminated prop */ + len = sizeof("/__overlay__/") - 1; + if ((e - s) < len || memcmp(s, "/__overlay__/", len)) + return -FDT_ERR_BADOVERLAY; + + rel_path = s + len; + rel_path_len = e - rel_path; + + /* find the fragment index in which the symbol lies */ + ret = fdt_subnode_offset_namelen(fdto, 0, frag_name, + frag_name_len); + /* not found? */ + if (ret < 0) + return -FDT_ERR_BADOVERLAY; + fragment = ret; + + /* an __overlay__ subnode must exist */ + ret = fdt_subnode_offset(fdto, fragment, "__overlay__"); + if (ret < 0) + return -FDT_ERR_BADOVERLAY; + + /* get the target of the fragment */ + ret = overlay_get_target(fdt, fdto, fragment, &target_path); + if (ret < 0) + return ret; + target = ret; + + /* if we have a target path use */ + if (!target_path) { + ret = get_path_len(fdt, target); + if (ret < 0) + return ret; + len = ret; + } else { + len = strlen(target_path); + } + + ret = fdt_setprop_placeholder(fdt, root_sym, name, + len + (len > 1) + rel_path_len + 1, &p); + if (ret < 0) + return ret; + + if (!target_path) { + /* again in case setprop_placeholder changed it */ + ret = overlay_get_target(fdt, fdto, fragment, &target_path); + if (ret < 0) + return ret; + target = ret; + } + + buf = p; + if (len > 1) { /* target is not root */ + if (!target_path) { + ret = fdt_get_path(fdt, target, buf, len + 1); + if (ret < 0) + return ret; + } else + memcpy(buf, target_path, len + 1); + + } else + len--; + + buf[len] = '/'; + memcpy(buf + len + 1, rel_path, rel_path_len); + buf[len + 1 + rel_path_len] = '\0'; + } + + return 0; +} + int fdt_overlay_apply(void *fdt, void *fdto) { uint32_t delta = fdt_get_max_phandle(fdt); @@ -654,6 +834,10 @@ int fdt_overlay_apply(void *fdt, void *fdto) if (ret) goto err;
+ ret = overlay_symbol_update(fdt, fdto); + if (ret) + goto err; + /* * The overlay has been damaged, erase its magic. */