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.ripard@xxxxxxxxxxxxxxxxxx>
---
libfdt/Makefile.libfdt | 2 +-
libfdt/fdt_overlay.c | 667 +++++++++++++++++++++++++++++++++++++++++++++++++
libfdt/libfdt.h | 32 +++
libfdt/libfdt_env.h | 1 +
4 files changed, 701 insertions(+), 1 deletion(-)
create mode 100644 libfdt/fdt_overlay.c
diff --git a/libfdt/Makefile.libfdt b/libfdt/Makefile.libfdt
index 09c322ed82ba..098b3f36e668 100644
--- a/libfdt/Makefile.libfdt
+++ b/libfdt/Makefile.libfdt
@@ -7,5 +7,5 @@ LIBFDT_soname = libfdt.$(SHAREDLIB_EXT).1
LIBFDT_INCLUDES = fdt.h libfdt.h libfdt_env.h
LIBFDT_VERSION = version.lds
LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_rw.c fdt_strerror.c fdt_empty_tree.c \
- fdt_addresses.c
+ fdt_addresses.c fdt_overlay.c
LIBFDT_OBJS = $(LIBFDT_SRCS:%.c=%.o)
diff --git a/libfdt/fdt_overlay.c b/libfdt/fdt_overlay.c
new file mode 100644
index 000000000000..72edbce093d9
--- /dev/null
+++ b/libfdt/fdt_overlay.c
@@ -0,0 +1,667 @@
+#include "libfdt_env.h"
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "libfdt_internal.h"
+
+/**
+ * overlay_get_target_phandle - retrieves the target phandle of a fragment
+ * @fdto: pointer to the device tree overlay blob
+ * @fragment: node offset of the fragment in the overlay
+ *
+ * overlay_get_target_phandle() retrieves the target phandle of an
+ * overlay fragment when that fragment uses a phandle (target
+ * property) instead of a path (target-path property).
+ *
+ * returns:
+ * the phandle pointed by the target property
+ * 0, if the phandle was not found
+ * -1, if the phandle was malformed
+ */
+static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
+{
+ const uint32_t *val;
+ int len;
+
+ val = fdt_getprop(fdto, fragment, "target", &len);
+ if (!val)
+ return 0;
+
+ if ((len != sizeof(*val)) || (*val == (uint32_t)-1))
+ return (uint32_t)-1;
+
+ return fdt32_to_cpu(*val);
+}
+
+/**
+ * overlay_get_target - retrieves the offset of a fragment's target
+ * @fdt: Base device tree blob
+ * @fdto: Device tree overlay blob
+ * @fragment: node offset of the fragment in the overlay
+ *
+ * overlay_get_target() retrieves the target offset in the base
+ * device tree of a fragment, no matter how the actual targetting is
+ * done (through a phandle or a path)
+ *
+ * returns:
+ * the targetted node offset in the base device tree
+ * Negative error code on error
+ */
+static int overlay_get_target(const void *fdt, const void *fdto,
+ int fragment)
+{
+ uint32_t phandle;
+ const char *path;
+ int path_len;
+
+ /* 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);
+
+ /* 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;
+
+ return path_len;
+ }
+
+ return fdt_path_offset(fdt, path);
+}
+
+/**
+ * overlay_phandle_add_offset - Increases a phandle by an offset
+ * @fdt: Base device tree blob
+ * @node: Device tree overlay blob
+ * @name: Name of the property to modify (phandle or linux,phandle)
+ * @delta: offset to apply
+ *
+ * overlay_phandle_add_offset() increments a node phandle by a given
+ * offset.
+ *
+ * returns:
+ * 0 on success.
+ * Negative error code on error
+ */
+static int overlay_phandle_add_offset(void *fdt, int node,
+ const char *name, uint32_t delta)
+{
+ const uint32_t *val;
+ uint32_t adj_val;
+ int len;
+
+ val = fdt_getprop(fdt, node, name, &len);
+ if (!val)
+ return len;
+
+ if (len != sizeof(*val))
+ return -FDT_ERR_BADSTRUCTURE;
+
+ adj_val = fdt32_to_cpu(*val);
+ if ((adj_val + delta) < adj_val)
+ return -FDT_ERR_NOPHANDLES;
+
+ adj_val += delta;
+ if (adj_val == (uint32_t)-1)
+ return -FDT_ERR_NOPHANDLES;
+
+ return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
+}
+
+/**
+ * overlay_adjust_node_phandles - Offsets the phandles of a node
+ * @fdto: Device tree overlay blob
+ * @node: Offset of the node we want to adjust
+ * @delta: Offset to shift the phandles of
+ *
+ * overlay_adjust_node_phandles() adds a constant to all the phandles
+ * of a given node. This is mainly use as part of the overlay
+ * application process, when we want to update all the overlay
+ * phandles to not conflict with the overlays of the base device tree.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_adjust_node_phandles(void *fdto, int node,
+ uint32_t delta)
+{
+ int child;
+ int ret;
+
+ ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ return ret;
+
+ ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ return ret;
+
+ fdt_for_each_subnode(child, fdto, node) {
+ ret = overlay_adjust_node_phandles(fdto, child, delta);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
+ * @fdto: Device tree overlay blob
+ * @delta: Offset to shift the phandles of
+ *
+ * overlay_adjust_local_phandles() adds a constant to all the
+ * phandles of an overlay. This is mainly use as part of the overlay
+ * application process, when we want to update all the overlay
+ * phandles to not conflict with the overlays of the base device tree.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
+{
+ /*
+ * Start adjusting the phandles from the overlay root
+ */
+ return overlay_adjust_node_phandles(fdto, 0, delta);
+}
+
+/**
+ * overlay_update_local_node_references - Adjust the overlay references
+ * @fdto: Device tree overlay blob
+ * @tree_node: Node offset of the node to operate on
+ * @fixup_node: Node offset of the matching local fixups node
+ * @delta: Offset to shift the phandles of
+ *
+ * overlay_update_local_nodes_references() update the phandles
+ * pointing to a node within the device tree overlay by adding a
+ * constant delta.
+ *
+ * This is mainly used as part of a device tree application process,
+ * where you want the device tree overlays phandles to not conflict
+ * with the ones from the base device tree before merging them.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_update_local_node_references(void *fdto,
+ int tree_node,
+ int fixup_node,
+ uint32_t delta)
+{
+ int fixup_prop;
+ int fixup_child;
+ int ret;
+
+ fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
+ const uint32_t *fixup_val;
+ const char *tree_val;
+ const char *name;
+ int fixup_len;
+ int tree_len;
+ int i;
+
+ fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
+ &name, &fixup_len);
+ if (!fixup_val)
+ return fixup_len;
+
+ if (fixup_len % sizeof(uint32_t))
+ return -FDT_ERR_BADSTRUCTURE;
+
+ tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
+ if (!tree_val) {
+ if (tree_len == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_BADOVERLAY;
+
+ return tree_len;
+ }
+
+ for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
+ uint32_t adj_val, index;
+
+ index = fdt32_to_cpu(fixup_val[i]);
+
+ /*
+ * phandles to fixup can be unaligned.
+ *
+ * Use a memcpy for the architectures that do
+ * not support unaligned accesses.
+ */
+ memcpy(&adj_val, tree_val + index, sizeof(adj_val));
+
+ adj_val = fdt32_to_cpu(adj_val);
+ adj_val += delta;
+ adj_val = cpu_to_fdt32(adj_val);
+
+ ret = fdt_setprop_inplace_namelen_partial(fdto,
+ tree_node,
+ name,
+ strlen(name),
+ index,
+ &adj_val,
+ sizeof(adj_val));
+ if (ret)
+ return ret;
+ }
+ }
+
+ fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
+ const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
+ NULL);
+ int tree_child;
+
+ tree_child = fdt_subnode_offset(fdto, tree_node,
+ fixup_child_name);
+ if (tree_child < 0)
+ return tree_child;
+
+ ret = overlay_update_local_node_references(fdto,
+ tree_child,
+ fixup_child,
+ delta);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * overlay_update_local_references - Adjust the overlay references
+ * @fdto: Device tree overlay blob
+ * @delta: Offset to shift the phandles of
+ *
+ * overlay_update_local_references() update all the phandles pointing
+ * to a node within the device tree overlay by adding a constant
+ * delta to not conflict with the base overlay.
+ *
+ * This is mainly used as part of a device tree application process,
+ * where you want the device tree overlays phandles to not conflict
+ * with the ones from the base device tree before merging them.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_update_local_references(void *fdto, uint32_t delta)
+{
+ int fixups;
+
+ fixups = fdt_path_offset(fdto, "/__local_fixups__");
+ if (fixups < 0) {
+ /* There's no local phandles to adjust, bail out */
+ if (fixups == -FDT_ERR_NOTFOUND)
+ return 0;
+
+ return fixups;
+ }
+
+ /*
+ * Update our local references from the root of the tree
+ */
+ return overlay_update_local_node_references(fdto, 0, fixups,
+ delta);
+}
+
+/**
+ * overlay_fixup_one_phandle - Set an overlay phandle to the base one
+ * @fdt: Base Device Tree blob
+ * @fdto: Device tree overlay blob
+ * @symbols_off: Node offset of the symbols node in the base device tree
+ * @path: Path to a node holding a phandle in the overlay
+ * @path_len: number of path characters to consider
+ * @name: Name of the property holding the phandle reference in the overlay
+ * @name_len: number of name characters to consider
+ * @index: Index in the overlay property where the phandle is stored
+ * @label: Label of the node referenced by the phandle
+ *
+ * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
+ * a node in the base device tree.
+ *
+ * This is part of the device tree overlay application process, when
+ * you want all the phandles in the overlay to point to the actual
+ * base dt nodes.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_fixup_one_phandle(void *fdt, void *fdto,
+ int symbols_off,
+ const char *path, uint32_t path_len,
+ const char *name, uint32_t name_len,
+ int index, const char *label)
+{
+ const char *symbol_path;
+ uint32_t phandle;
+ int symbol_off, fixup_off;
+ int prop_len;
+
+ symbol_path = fdt_getprop(fdt, symbols_off, label,
+ &prop_len);
+ if (!symbol_path)
+ return prop_len;
+
+ 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_namelen(fdto, path, path_len);
+ if (fixup_off == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_BADOVERLAY;
+ if (fixup_off < 0)
+ return fixup_off;
+
+ phandle = cpu_to_fdt32(phandle);
+ return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
+ name, name_len, index,
+ &phandle, sizeof(phandle));
+};
+
+/**
+ * overlay_fixup_phandle - Set an overlay phandle to the base one
+ * @fdt: Base Device Tree blob
+ * @fdto: Device tree overlay blob
+ * @symbols_off: Node offset of the symbols node in the base device tree
+ * @property: Property offset in the overlay holding the list of fixups
+ *
+ * overlay_fixup_phandle() resolves all the overlay phandles pointed
+ * to in a __fixups__ property, and updates them to match the phandles
+ * in use in the base device tree.
+ *
+ * This is part of the device tree overlay application process, when
+ * you want all the phandles in the overlay to point to the actual
+ * base dt nodes.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
+ int property)
+{
+ const char *value;
+ const char *label;
+ int len;
+
+ value = fdt_getprop_by_offset(fdto, property,
+ &label, &len);
+ if (!value) {
+ if (len == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_INTERNAL;
+
+ return len;
+ }
+
+ do {
+ const char *path, *name, *fixup_end;
+ const char *fixup_str = value;
+ uint32_t path_len, name_len;
+ uint32_t fixup_len;
+ char *sep, *endptr;
+ int index, ret;
+
+ fixup_end = memchr(value, '\0', len);
+ if (!fixup_end)
+ return -FDT_ERR_BADFIXUP;
+ fixup_len = fixup_end - fixup_str;
+
+ len -= fixup_len + 1;
+ value += fixup_len + 1;
+
+ path = fixup_str;
+ sep = memchr(fixup_str, ':', fixup_len);
+ if (!sep || *sep != ':')
+ return -FDT_ERR_BADFIXUP;
+
+ path_len = sep - path;
+ if (path_len == (fixup_len - 1))
+ return -FDT_ERR_BADFIXUP;
+
+ fixup_len -= path_len + 1;
+ name = sep + 1;
+ sep = memchr(name, ':', fixup_len);
+ if (!sep || *sep != ':')
+ return -FDT_ERR_BADFIXUP;
+
+ name_len = sep - name;
+ if (!name_len)
+ return -FDT_ERR_BADFIXUP;
+
+ index = strtoul(sep + 1, &endptr, 10);
+ if ((*endptr != '\0') || (endptr <= (sep + 1)))
+ return -FDT_ERR_BADFIXUP;
+
+ ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
+ path, path_len, name, name_len,
+ index, label);
+ if (ret)
+ return ret;
+ } while (len > 0);
+
+ return 0;
+}
+
+/**
+ * overlay_fixup_phandles - Resolve the overlay phandles to the base
+ * device tree
+ * @fdt: Base Device Tree blob
+ * @fdto: Device tree overlay blob
+ *
+ * overlay_fixup_phandles() resolves all the overlay phandles pointing
+ * to nodes in the base device tree.
+ *
+ * This is one of the steps of the device tree overlay application
+ * process, when you want all the phandles in the overlay to point to
+ * the actual base dt nodes.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_fixup_phandles(void *fdt, void *fdto)
+{
+ int fixups_off, symbols_off;
+ int property;
+
+ /* We can have overlays without any fixups */
+ fixups_off = fdt_path_offset(fdto, "/__fixups__");
+ if (fixups_off == -FDT_ERR_NOTFOUND)
+ return 0;
+ if (fixups_off < 0)
+ return fixups_off;
+
+ symbols_off = fdt_path_offset(fdt, "/__symbols__");
+ if (symbols_off < 0)
+ return symbols_off;
+
+ fdt_for_each_property_offset(property, fdto, fixups_off) {
+ int ret;
+
+ ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * overlay_apply_node - Merges a node into the base device tree
+ * @fdt: Base Device Tree blob
+ * @target: Node offset in the base device tree to apply the fragment to
+ * @fdto: Device tree overlay blob
+ * @node: Node offset in the overlay holding the changes to merge
+ *
+ * overlay_apply_node() merges a node into a target base device tree
+ * node pointed.
+ *
+ * This is part of the final 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.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_apply_node(void *fdt, int target,
+ void *fdto, int node)
+{
+ int property;
+ int subnode;
+
+ fdt_for_each_property_offset(property, fdto, node) {
+ const char *name;
+ const void *prop;
+ int prop_len;
+ int ret;
+
+ prop = fdt_getprop_by_offset(fdto, property, &name,
+ &prop_len);
+ if (prop_len == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_INTERNAL;
+ if (prop_len < 0)
+ return prop_len;
+
+ ret = fdt_setprop(fdt, target, name, prop, prop_len);
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(subnode, fdto, node) {
+ const char *name = fdt_get_name(fdto, subnode, NULL);
+ int nnode;
+ int ret;
+
+ nnode = fdt_add_subnode(fdt, target, name);
+ if (nnode == -FDT_ERR_EXISTS) {
+ nnode = fdt_subnode_offset(fdt, target, name);
+ if (nnode == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_INTERNAL;
+ }
+
+ if (nnode < 0)
+ return nnode;
+
+ ret = overlay_apply_node(fdt, nnode, fdto, subnode);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * overlay_merge - Merge an overlay into its base device tree
+ * @fdt: Base Device Tree blob
+ * @fdto: Device tree overlay blob
+ *
+ * overlay_merge() merges an overlay into its base device tree.
+ *
+ * This is the final 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.
+ *
+ * returns:
+ * 0 on success
+ * Negative error code on failure
+ */
+static int overlay_merge(void *fdt, void *fdto)
+{
+ int fragment;
+
+ fdt_for_each_subnode(fragment, fdto, 0) {
+ int overlay;
+ int target;
+ int ret;
+
+ /*
+ * Each fragments will have an __overlay__ node. If
+ * they don't, it's not supposed to be merged
+ */
+ overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
+ if (overlay == -FDT_ERR_NOTFOUND)
+ continue;
+
+ if (overlay < 0)
+ return overlay;
+
+ target = overlay_get_target(fdt, fdto, fragment);
+ if (target < 0)
+ return target;
+
+ ret = overlay_apply_node(fdt, target, fdto, overlay);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+int fdt_overlay_apply(void *fdt, void *fdto)
+{
+ uint32_t delta = fdt_get_max_phandle(fdt);
+ int ret;
+
+ FDT_CHECK_HEADER(fdt);
+ FDT_CHECK_HEADER(fdto);
+
+ ret = overlay_adjust_local_phandles(fdto, delta);
+ if (ret)
+ goto err;
+
+ ret = overlay_update_local_references(fdto, delta);
+ if (ret)
+ goto err;
+
+ ret = overlay_fixup_phandles(fdt, fdto);
+ if (ret)
+ goto err;
+
+ ret = overlay_merge(fdt, fdto);
+ if (ret)
+ goto err;
+
+ /*
+ * The overlay has been damaged, erase its magic.
+ */
+ fdt_set_magic(fdto, ~0);
+
+ return 0;
+
+err:
+ /*
+ * The overlay might have been damaged, erase its magic.
+ */
+ fdt_set_magic(fdto, ~0);
+
+ /*
+ * The base device tree might have been damaged, erase its
+ * magic.
+ */
+ fdt_set_magic(fdt, ~0);
+
+ return ret;
+}
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index 133782c6ea69..a447441bd7db 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -1767,6 +1767,38 @@ 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,
+ * -FDT_ERR_BADOVERLAY,
+ * -FDT_ERR_NOPHANDLES,
+ * -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_BADFIXUP,
+ * -FDT_ERR_TRUNCATED, standard meanings
+ */
+int fdt_overlay_apply(void *fdt, void *fdto);
+
/**********************************************************************/
/* Debugging / informational functions */
/**********************************************************************/
diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
index 9dea97dfff81..99f936dacc60 100644
--- a/libfdt/libfdt_env.h
+++ b/libfdt/libfdt_env.h
@@ -54,6 +54,7 @@
#include <stddef.h>
#include <stdint.h>
+#include <stdlib.h>
#include <string.h>
#ifdef __CHECKER__
--
2.9.3
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