On Fri, Sep 30, 2016 at 03:57:16PM +0200, Maxime Ripard wrote: > 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> One tiny nit to think about fixing in a follow up patch, otherwise looks good. > --- > libfdt/Makefile.libfdt | 2 +- > libfdt/fdt_overlay.c | 670 +++++++++++++++++++++++++++++++++++++++++++++++++ > libfdt/libfdt.h | 31 +++ > libfdt/libfdt_env.h | 1 + > 4 files changed, 703 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..c7e5508abf30 > --- /dev/null > +++ b/libfdt/fdt_overlay.c > @@ -0,0 +1,670 @@ > +#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_BADPHANDLE; > + > + 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_BADOVERLAY; > + > + 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 == -FDT_ERR_NOSPACE) > + return -FDT_ERR_BADOVERLAY; > + > + 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; Technically a NOTFOUND here should also be translated into a BADOVERLAY, but I'm not going to hold the patch up just for that. > + > + 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_BADOVERLAY; > + 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_BADOVERLAY; > + > + path_len = sep - path; > + if (path_len == (fixup_len - 1)) > + return -FDT_ERR_BADOVERLAY; > + > + fixup_len -= path_len + 1; > + name = sep + 1; > + sep = memchr(name, ':', fixup_len); > + if (!sep || *sep != ':') > + return -FDT_ERR_BADOVERLAY; > + > + name_len = sep - name; > + if (!name_len) > + return -FDT_ERR_BADOVERLAY; > + > + index = strtoul(sep + 1, &endptr, 10); > + if ((*endptr != '\0') || (endptr <= (sep + 1))) > + return -FDT_ERR_BADOVERLAY; > + > + 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 d2e5e031fb35..c69e9188996f 100644 > --- a/libfdt/libfdt.h > +++ b/libfdt/libfdt.h > @@ -1763,6 +1763,37 @@ 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_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__ -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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