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@free-electrons.com --- include/libfdt.h | 30 ++++ lib/Kconfig | 5 + lib/libfdt/Makefile | 2 + lib/libfdt/fdt_overlay.c | 405 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 442 insertions(+) create mode 100644 lib/libfdt/fdt_overlay.c
diff --git a/include/libfdt.h b/include/libfdt.h index 4c56711c7132..b6a400a7a823 100644 --- a/include/libfdt.h +++ b/include/libfdt.h @@ -1740,6 +1740,36 @@ 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/Kconfig b/lib/Kconfig index 02ca4058d37e..16ff01a2cd37 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -139,6 +139,11 @@ config OF_LIBFDT particular compatible nodes. The library operates on a flattened version of the device tree.
+config OF_LIBFDT_OVERLAY + bool "Enable the FDT library overlay support" + help + This enables the FDT library (libfdt) overlay support. + config SPL_OF_LIBFDT bool "Enable the FDT library for SPL" default y if SPL_OF_CONTROL diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile index 8b86c15904cb..6ef8290f4e09 100644 --- a/lib/libfdt/Makefile +++ b/lib/libfdt/Makefile @@ -15,3 +15,5 @@ obj-y += \ fdt_empty_tree.o \ fdt_addresses.o \ fdt_region.o + +obj-$(CONFIG_OF_LIBFDT_OVERLAY) += fdt_overlay.o diff --git a/lib/libfdt/fdt_overlay.c b/lib/libfdt/fdt_overlay.c new file mode 100644 index 000000000000..c45e8b25fb06 --- /dev/null +++ b/lib/libfdt/fdt_overlay.c @@ -0,0 +1,405 @@ +#include "libfdt_env.h" + +#include <fdt.h> +#include <libfdt.h> + +#include "libfdt_internal.h" + +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 == 0xffffffff) || (len != sizeof(*val))) + return 0xffffffff; + + return fdt32_to_cpu(*val); +} + +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 == -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); +} + +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); +} + +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; +} + +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); +} + +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 *val = NULL; + uint32_t adj_val, index; + const char *name; + int fixup_len; + int tree_len; + + val = fdt_getprop_by_offset(fdto, fixup_prop, + &name, &fixup_len); + if (!val) + return fixup_len; + index = fdt32_to_cpu(*val); + + val = fdt_getprop(fdto, tree_node, name, &tree_len); + if (!val) + return tree_len; + + /* + * The index can be unaligned. + * + * Use a memcpy for the architectures that do not + * support unaligned accesses. + */ + memcpy(&adj_val, (unsigned char *)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_by_index(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; +} + +static int overlay_update_local_references(void *dto, uint32_t delta) +{ + int fixups; + + fixups = fdt_path_offset(dto, "/__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(dto, 0, fixups, + delta); +} + +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_by_index(fdto, fixup_off, + name, name_len, index, + &phandle, sizeof(phandle)); +}; + +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; +} + +static int 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_offset(property, dto, fixups_off) + overlay_fixup_phandle(dt, dto, symbols_off, property); + + return 0; +} + +static int apply_overlay_node(void *dt, int target, + void *dto, int fragment) +{ + int property; + int node; + + fdt_for_each_property_offset(property, dto, fragment) { + const char *name; + const void *prop; + int prop_len; + int ret; + + prop = fdt_getprop_by_offset(dto, property, &name, + &prop_len); + if (prop_len == -FDT_ERR_NOTFOUND) + return -FDT_ERR_INTERNAL; + if (prop_len < 0) + return prop_len; + + ret = fdt_setprop(dt, target, name, prop, prop_len); + if (ret) + return ret; + } + + fdt_for_each_subnode(dto, node, fragment) { + const char *name = fdt_get_name(dto, node, NULL); + int nnode; + int ret; + + nnode = fdt_add_subnode(dt, target, name); + if (nnode == -FDT_ERR_EXISTS) + nnode = fdt_subnode_offset(dt, target, name); + + if (nnode < 0) + return nnode; + + ret = apply_overlay_node(dt, nnode, dto, node); + if (ret) + return ret; + } + + return 0; +} + +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 = apply_overlay_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; +}