The device tree overlays are a good way to deal with user-modifyable
boards or boards with some kind of an expansion mechanism where we can
easily plug new board in (like the BBB, the Raspberry Pi or the CHIP).
Add a new function to merge overlays with a base device tree.
Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
---
include/libfdt.h | 30 ++++
lib/libfdt/Makefile | 2 +-
lib/libfdt/fdt_overlay.c | 414 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 445 insertions(+), 1 deletion(-)
create mode 100644 lib/libfdt/fdt_overlay.c
diff --git a/include/libfdt.h b/include/libfdt.h
index 1e01b2c7ebdf..783067e841a1 100644
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -1698,6 +1698,36 @@ int fdt_add_subnode(void *fdt, int parentoffset, const
char *name);
*/
int fdt_del_node(void *fdt, int nodeoffset);
+/**
+ * fdt_overlay_apply - Applies a DT overlay on a base DT
+ * @fdt: pointer to the base device tree blob
+ * @fdto: pointer to the device tree overlay blob
+ *
+ * fdt_overlay_apply() will apply the given device tree overlay on the
+ * given base device tree.
+ *
+ * Expect the base device tree to be modified, even if the function
+ * returns an error.
+ *
+ * returns:
+ * 0, on success
+ * -FDT_ERR_NOSPACE, there's not enough space in the base device tree
+ * -FDT_ERR_NOTFOUND, the overlay points to some inexistant nodes or
+ * properties in the base DT
+ * -FDT_ERR_BADPHANDLE, the phandles in the overlay do not have the right
+ * magic
+ * -FDT_ERR_INTERNAL,
+ * -FDT_ERR_BADLAYOUT,
+ * -FDT_ERR_BADMAGIC,
+ * -FDT_ERR_BADOFFSET,
+ * -FDT_ERR_BADPATH,
+ * -FDT_ERR_BADVERSION,
+ * -FDT_ERR_BADSTRUCTURE,
+ * -FDT_ERR_BADSTATE,
+ * -FDT_ERR_TRUNCATED, standard meanings
+ */
+int fdt_overlay_apply(void *fdt, void *fdto);
+
/**********************************************************************/
/* Debugging / informational functions */
/**********************************************************************/
diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile
index 934d6142c3e9..4935bf012a75 100644
--- a/lib/libfdt/Makefile
+++ b/lib/libfdt/Makefile
@@ -6,4 +6,4 @@
#
obj-y += fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o fdt_wip.o \
- fdt_empty_tree.o fdt_addresses.o fdt_region.o
+ fdt_empty_tree.o fdt_addresses.o fdt_region.o fdt_overlay.o
diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c
new file mode 100644
index 000000000000..1e68e903c734
--- /dev/null
+++ b/lib/libfdt/fdt_overlay.c
@@ -0,0 +1,414 @@
+#include "libfdt_env.h"
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "libfdt_internal.h"
+
+static uint32_t fdt_overlay_get_target_phandle(const void *fdto, int node)
+{
+ const uint32_t *val;
+ int len;
+
+ val = fdt_getprop(fdto, node, "target", &len);
+ if (!val || (len != sizeof(*val)))
+ return 0;
+
+ return fdt32_to_cpu(*val);
+}
+
+static int fdt_overlay_get_target(const void *fdt, const void *fdto,
+ int fragment)
+{
+ uint32_t phandle;
+ const char *path;
+
+ /* Try first to do a phandle based lookup */
+ phandle = fdt_overlay_get_target_phandle(fdto, fragment);
+ if (phandle)
+ return fdt_node_offset_by_phandle(fdt, phandle);
+
+ /* And then a path based lookup */
+ path = fdt_getprop(fdto, fragment, "target-path", NULL);
+ if (!path)
+ return -FDT_ERR_NOTFOUND;
+
+ return fdt_path_offset(fdt, path);
+}
+
+static int fdt_overlay_adjust_node_phandles(void *fdto, int node,
+ uint32_t delta)
+{
+ int property;
+ int child;
+
+ fdt_for_each_property(fdto, node, property) {
+ const uint32_t *val;
+ const char *name;
+ uint32_t adj_val;
+ int len;
+ int ret;
+
+ val = fdt_getprop_by_offset(fdto, property,
+ &name, &len);
+ if (!val || (len != sizeof(*val)))
+ continue;
+
+ if (strcmp(name, "phandle") && strcmp(name, "linux,phandle"))
+ continue;
+
+ adj_val = fdt32_to_cpu(*val);
+ adj_val += delta;
+ ret = fdt_setprop_inplace_u32(fdto, node, name, adj_val);
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(fdto, child, node)
+ fdt_overlay_adjust_node_phandles(fdto, child, delta);
+
+ return 0;
+}
+
+static int fdt_overlay_adjust_local_phandles(void *fdto, uint32_t delta)
+{
+ int root;
+
+ root = fdt_path_offset(fdto, "/");
+ if (root < 0)
+ return root;
+
+ return fdt_overlay_adjust_node_phandles(fdto, root, delta);
+}
+
+static int _fdt_overlay_update_local_references(void *fdto,
+ int tree_node,
+ int fixup_node,
+ uint32_t delta)
+{
+ int fixup_prop;
+ int fixup_child;
+
+ fdt_for_each_property(fdto, fixup_node, fixup_prop) {
+ const char *fixup_name, *tree_name;
+ const uint32_t *val = NULL;
+ uint32_t adj_val;
+ int fixup_len;
+ int tree_prop;
+ int tree_len;
+ int ret;
+
+ fdt_getprop_by_offset(fdto, fixup_prop,
+ &fixup_name, &fixup_len);
+
+ if (!strcmp(fixup_name, "phandle") ||
+ !strcmp(fixup_name, "linux,phandle"))
+ continue;
+
+ fdt_for_each_property(fdto, tree_node, tree_prop) {
+ val = fdt_getprop_by_offset(fdto, tree_prop,
+ &tree_name, &tree_len);
+
+ if (!strcmp(tree_name, fixup_name))
+ break;
+ }
+
+ if (!val || !tree_len)
+ return -FDT_ERR_NOTFOUND;
+
+ if (!tree_name)
+ return -FDT_ERR_NOTFOUND;
+
+ if (tree_len != 4)
+ return -FDT_ERR_NOTFOUND;
+
+ adj_val = fdt32_to_cpu(*val);
+ adj_val += delta;
+ ret = fdt_setprop_inplace_u32(fdto, tree_node, fixup_name,
+ adj_val);
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(fdto, fixup_child, fixup_node) {
+ const char *fixup_child_name = fdt_get_name(fdto,
+ fixup_child, NULL);
+ int tree_child;
+
+ fdt_for_each_subnode(fdto, tree_child, tree_node) {
+ const char *tree_child_name = fdt_get_name(fdto,
+ tree_child,
+ NULL);
+
+ if (!strcmp(fixup_child_name, tree_child_name))
+ break;
+ }
+
+ _fdt_overlay_update_local_references(fdto,
+ tree_child,
+ fixup_child,
+ delta);
+ }
+
+ return 0;
+}
+
+static int fdt_overlay_update_local_references(void *dto, uint32_t delta)
+{
+ int root, fixups;
+
+ root = fdt_path_offset(dto, "/");
+ if (root < 0)
+ return root;
+
+ fixups = fdt_path_offset(dto, "/__local_fixups__");
+ if (root < 0)
+ return root;
+
+ return _fdt_overlay_update_local_references(dto, root, fixups,
+ delta);
+}
+
+static int _fdt_overlay_fixup_phandle(void *fdt, void *fdto,
+ int symbols_off,
+ const char *path, const char *name,
+ int index, const char *label)
+{
+ const uint32_t *prop_val;
+ const char *symbol_path;
+ uint32_t *fixup_val;
+ uint32_t phandle;
+ int symbol_off, fixup_off;
+ int prop_len;
+ int ret;
+
+ symbol_path = fdt_getprop(fdt, symbols_off, label,
+ &prop_len);
+ if (!symbol_path)
+ return -FDT_ERR_NOTFOUND;
+
+ symbol_off = fdt_path_offset(fdt, symbol_path);
+ if (symbol_off < 0)
+ return symbol_off;
+
+ phandle = fdt_get_phandle(fdt, symbol_off);
+ if (!phandle)
+ return -FDT_ERR_NOTFOUND;
+
+ fixup_off = fdt_path_offset(fdto, path);
+ if (fixup_off < 0)
+ return fixup_off;
+
+ prop_val = fdt_getprop(fdto, fixup_off, name,
+ &prop_len);
+ if (!prop_val)
+ return -FDT_ERR_NOTFOUND;
+
+ fixup_val = malloc(prop_len);
+ if (!fixup_val)
+ return -FDT_ERR_INTERNAL;
+ memcpy(fixup_val, prop_val, prop_len);
+
+ if (fdt32_to_cpu(fixup_val[index]) != 0xdeadbeef) {
+ ret = -FDT_ERR_BADPHANDLE;
+ goto out;
+ }
+
+ fixup_val[index] = cpu_to_fdt32(phandle);
+ ret = fdt_setprop_inplace(fdto, fixup_off,
+ name, fixup_val,
+ prop_len);
+
+out:
+ free(fixup_val);
+ return ret;
+};
+
+static int fdt_overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
+ int property)
+{
+ const char *value, *tmp_value;
+ const char *label;
+ int tmp_len, len, next;
+ int table = 0;
+ int i;
+
+ value = fdt_getprop_by_offset(fdto, property,
+ &label, &len);
+ tmp_value = value;
+ tmp_len = len;
+
+ do {
+ next = strlen(tmp_value) + 1;
+ tmp_len -= next;
+ tmp_value += next;
+ table++;
+ } while (tmp_len > 0);
+
+ for (i = 0; i < table; i++) {
+ const char *prop_string = value;
+ const char *path, *name;
+ char *prop_cpy, *prop_tmp;
+ int index, stlen;
+ char *sep;
+
+ stlen = strlen(prop_string);
+ prop_cpy = malloc(stlen + 1);
+ if (!prop_cpy)
+ return -FDT_ERR_INTERNAL;
+
+ strncpy(prop_cpy, prop_string, stlen);
+ prop_cpy[stlen] = '\0';
+
+ for (prop_tmp = prop_cpy; (sep = strchr(prop_tmp, ':'));
+ prop_tmp += ((sep - prop_tmp) + 1))
+ *sep = '\0';
+
+ prop_tmp = prop_cpy;
+ path = prop_tmp;
+ prop_tmp += strlen(prop_tmp) + 1;
+
+ name = prop_tmp;
+ prop_tmp += strlen(prop_tmp) + 1;
+
+ index = strtol(prop_tmp, NULL, 10);
+ prop_tmp += strlen(prop_tmp) + 1;
+
+ value += stlen + 1;
+ len -= stlen + 1;
+
+ _fdt_overlay_fixup_phandle(fdt, fdto, symbols_off,
+ path, name, index, label);
+
+ free(prop_cpy);
+ }
+
+ return 0;
+}
+
+static int fdt_overlay_fixup_phandles(void *dt, void *dto)
+{
+ int fixups_off, symbols_off;
+ int property;
+
+ symbols_off = fdt_path_offset(dt, "/__symbols__");
+ fixups_off = fdt_path_offset(dto, "/__fixups__");
+
+ fdt_for_each_property(dto, fixups_off, property)
+ fdt_overlay_fixup_phandle(dt, dto, symbols_off, property);
+
+ return 0;
+}
+
+static int fdt_apply_overlay_node(void *dt, void *dto,
+ int target, int overlay)
+{
+ int property;
+ int node;
+
+ fdt_for_each_property(dto, overlay, property) {
+ const char *name;
+ const void *prop;
+ int prop_len;
+ int ret;
+
+ prop = fdt_getprop_by_offset(dto, property, &name,
+ &prop_len);
+ if (!prop)
+ return -FDT_ERR_INTERNAL;
+
+ ret = fdt_setprop(dt, target, name, prop, prop_len);
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(dto, node, overlay) {
+ const char *name = fdt_get_name(dto, node, NULL);
+ int nnode;
+ int ret;
+
+ nnode = fdt_add_subnode(dt, target, name);
+ if (nnode < 0)
+ return nnode;
+
+ ret = fdt_apply_overlay_node(dt, dto, nnode, node);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int fdt_overlay_merge(void *dt, void *dto)
+{
+ int root, fragment;
+
+ root = fdt_path_offset(dto, "/");
+ if (root < 0)
+ return root;
+
+ fdt_for_each_subnode(dto, fragment, root) {
+ const char *name = fdt_get_name(dto, fragment, NULL);
+ uint32_t target;
+ int overlay;
+ int ret;
+
+ if (strncmp(name, "fragment", 8))
+ continue;
+
+ target = fdt_overlay_get_target(dt, dto, fragment);
+ if (target < 0)
+ return target;
+
+ overlay = fdt_subnode_offset(dto, fragment, "__overlay__");
+ if (overlay < 0)
+ return overlay;
+
+ ret = fdt_apply_overlay_node(dt, dto, target, overlay);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+int fdt_overlay_apply(void *fdt, void *fdto)
+{
+ uint32_t delta = fdt_get_max_phandle(fdt) + 1;
+ void *fdto_copy;
+ int ret;
+
+ FDT_CHECK_HEADER(fdt);
+ FDT_CHECK_HEADER(fdto);
+
+ /*
+ * We're going to modify the overlay so that we can apply it.
+ *
+ * Make sure sure we don't destroy the original
+ */
+ fdto_copy = malloc(fdt_totalsize(fdto));
+ if (!fdto_copy)
+ return -FDT_ERR_INTERNAL;
+
+ ret = fdt_move(fdto, fdto_copy, fdt_totalsize(fdto));
+ if (ret)
+ goto out;
+
+ ret = fdt_overlay_adjust_local_phandles(fdto_copy, delta);
+ if (ret)
+ goto out;
+
+ ret = fdt_overlay_update_local_references(fdto_copy, delta);
+ if (ret)
+ goto out;
+
+ ret = fdt_overlay_fixup_phandles(fdt, fdto_copy);
+ if (ret)
+ goto out;
+
+ ret = fdt_overlay_merge(fdt, fdto_copy);
+
+out:
+ free(fdto_copy);
+ return ret;
+}
--
2.8.2
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