diff options
Diffstat (limited to 'lib/libfdt/fdt_overlay.c')
| -rw-r--r-- | lib/libfdt/fdt_overlay.c | 618 |
1 files changed, 618 insertions, 0 deletions
diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c new file mode 100644 index 0000000000..40b6d27455 --- /dev/null +++ b/lib/libfdt/fdt_overlay.c @@ -0,0 +1,618 @@ +#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 ((*val == (uint32_t)-1) || (len != sizeof(*val))) + return (uint32_t)-1; + + return fdt32_to_cpu(*val); +} + +/** + * overlay_get_target - retrieves the target phandle of a fragment + * @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 phandle 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; + + /* 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", NULL); + if (!path) + return -FDT_ERR_NOTFOUND; + + 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_BADPHANDLE; + + adj_val += delta; + 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) +{ + bool found = false; + int child; + int ret; + + ret = overlay_phandle_add_offset(fdto, node, "phandle", delta); + if (ret && ret != -FDT_ERR_NOTFOUND) + return ret; + + if (!ret) + found = true; + + ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta); + if (ret && ret != -FDT_ERR_NOTFOUND) + return ret; + + /* + * If neither phandle nor linux,phandle have been found return + * an error. + */ + if (!found && !ret) + return ret; + + fdt_for_each_subnode(fdto, child, node) + overlay_adjust_node_phandles(fdto, child, delta); + + 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 unsigned char *fixup_val, *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; + + tree_val = fdt_getprop(fdto, tree_node, name, &tree_len); + if (!tree_val) + return tree_len; + + for (i = 0; i < fixup_len; i += sizeof(uint32_t)) { + uint32_t adj_val, index; + + index = *(uint32_t *)(fixup_val + i); + index = fdt32_to_cpu(index); + + /* + * 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(uint32_t)); + + 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(fdto, fixup_child, 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 -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_namelen(fdto, path, path_len); + 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 __local_fixup__ 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) + return len; + + do { + const char *prop_string = value; + const char *path, *name; + uint32_t prop_len = strlen(value); + uint32_t path_len, name_len; + char *sep, *endptr; + int index; + int ret; + + path = prop_string; + sep = memchr(prop_string, ':', prop_len); + if (*sep != ':') + return -FDT_ERR_BADSTRUCTURE; + path_len = sep - path; + + name = sep + 1; + sep = memchr(name, ':', prop_len); + if (*sep != ':') + return -FDT_ERR_BADSTRUCTURE; + name_len = sep - name; + + index = strtoul(sep + 1, &endptr, 10); + if ((*endptr != '\0') || (endptr <= (sep + 1))) + return -FDT_ERR_BADSTRUCTURE; + + len -= prop_len + 1; + value += prop_len + 1; + + 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; + + symbols_off = fdt_path_offset(fdt, "/__symbols__"); + fixups_off = fdt_path_offset(fdto, "/__fixups__"); + + 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 - Merge an overlay fragment 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 + * @fragment: Node offset in the overlay holding the changes to merge + * + * overlay_apply_node() merges an overlay fragment 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 fragment) +{ + int property; + int node; + + fdt_for_each_property_offset(property, fdto, fragment) { + 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(fdto, node, fragment) { + const char *name = fdt_get_name(fdto, node, 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 < 0) + return nnode; + + ret = overlay_apply_node(fdt, nnode, fdto, node); + 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 *dt, void *dto) +{ + int fragment; + + fdt_for_each_subnode(dto, fragment, 0) { + int overlay; + int target; + int ret; + + target = overlay_get_target(dt, dto, fragment); + if (target < 0) + continue; + + overlay = fdt_subnode_offset(dto, fragment, "__overlay__"); + if (overlay < 0) + return overlay; + + ret = overlay_apply_node(dt, target, dto, overlay); + if (ret) + return ret; + } + + return 0; +} + +int fdt_overlay_apply(void *fdt, void *fdto) +{ + uint32_t delta = fdt_get_max_phandle(fdt) + 1; + 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; +} |