Introduce a tool which scores devicetrees based on their board-id and a supplied reference devicetree. This mechanism would be most similar to an proposal to EBBR where firmware provides a reference devicetree which contains the actual board identifier values, and an OS loader can choose to replace (or overlay) the firmware-provided devicetree.
Signed-off-by: Elliot Berman quic_eberman@quicinc.com --- scripts/dtc/.gitignore | 1 + scripts/dtc/Makefile | 3 +- scripts/dtc/fdt-select-board.c | 126 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 129 insertions(+), 1 deletion(-)
diff --git a/scripts/dtc/.gitignore b/scripts/dtc/.gitignore index e0b5c1d2464a..7f6d5202c0ba 100644 --- a/scripts/dtc/.gitignore +++ b/scripts/dtc/.gitignore @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0-only /dtc /fdtoverlay +/fdt-select-board diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile index 4d32b9497da9..a331f07091b3 100644 --- a/scripts/dtc/Makefile +++ b/scripts/dtc/Makefile @@ -2,7 +2,7 @@ # scripts/dtc makefile
# *** Also keep .gitignore in sync when changing *** -hostprogs-always-$(CONFIG_DTC) += dtc fdtoverlay +hostprogs-always-$(CONFIG_DTC) += dtc fdtoverlay fdt-select-board hostprogs-always-$(CHECK_DT_BINDING) += dtc
dtc-objs := dtc.o flattree.o fstree.o data.o livetree.o treesource.o \ @@ -14,6 +14,7 @@ dtc-objs += dtc-lexer.lex.o dtc-parser.tab.o libfdt-objs := fdt.o fdt_ro.o fdt_wip.o fdt_sw.o fdt_rw.o fdt_strerror.o fdt_empty_tree.o fdt_addresses.o fdt_overlay.o libfdt = $(addprefix libfdt/,$(libfdt-objs)) fdtoverlay-objs := $(libfdt) fdtoverlay.o util.o +fdt-select-board-objs := $(libfdt) fdt-select-board.o util.o
# Source files need to get at the userspace version of libfdt_env.h to compile HOST_EXTRACFLAGS += -I $(srctree)/$(src)/libfdt diff --git a/scripts/dtc/fdt-select-board.c b/scripts/dtc/fdt-select-board.c new file mode 100644 index 000000000000..a7f3dc715ed1 --- /dev/null +++ b/scripts/dtc/fdt-select-board.c @@ -0,0 +1,126 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved. + */ +#include <ctype.h> +#include <getopt.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <inttypes.h> + +#include <libfdt.h> + +#include "util.h" + +static const char usage_synopsis[] = + "find the best matching device tree from a reference board\n" + " fdt-select-board <options> [<candidate.dtb>]\n" + "\n"; +static const char usage_short_opts[] = "r:av" USAGE_COMMON_SHORT_OPTS; +static const struct option usage_long_opts[] = { + {"reference", required_argument, NULL, 'r'}, + {"verbose", no_argument, NULL, 'v'}, + {"all", no_argument, NULL, 'a'}, + USAGE_COMMON_LONG_OPTS +}; + +static const char * const usage_opts_help[] = { + "Reference DTB", + "Verbose messages", + "List all matches", + USAGE_COMMON_OPTS_HELP +}; + +int verbose = 0; + +struct context { + const void *fdt; + int node; +}; + +static const void *get_board_id(void *ctx, const char *name, int *datalen) +{ + struct context *c = ctx; + + return fdt_getprop(c->fdt, c->node, name, datalen); +} + +int main(int argc, char *argv[]) +{ + int opt; + char *input_filename = NULL; + const void *fdt; + const void *ref; + int ref_node; + int max_score = -1; + const char *best_match = NULL; + struct context ctx; + int all = 0; + + while ((opt = util_getopt_long()) != EOF) { + switch (opt) { + case_USAGE_COMMON_FLAGS + + case 'a': + all = 1; + break; + case 'r': + input_filename = optarg; + break; + case 'v': + verbose = 1; + break; + } + } + + if (!input_filename) + usage("missing reference file"); + + argv += optind; + argc -= optind; + + if (argc <= 0) + usage("missing candidate dtbs"); + + ref = utilfdt_read(input_filename, NULL); + if (!ref) { + fprintf(stderr, "failed to read reference %s\n", input_filename); + return -1; + } + + ref_node = fdt_path_offset(ref, "/board-id"); + if (ref_node < 0) { + fprintf(stderr, "reference blob doesn't have a board-id\n"); + return -1; + } + + ctx.fdt = ref; + ctx.node = ref_node; + + for (; argc > 0; --argc, ++argv) { + int score; + + fdt = utilfdt_read(*argv, NULL); + if (!fdt) { + fprintf(stderr, "failed to read %s\n", *argv); + return -1; + } + + score = fdt_board_id_score(fdt, get_board_id, &ctx); + if (verbose || (score > 0 && all)) + printf("%s: %d\n", *argv, score); + + if (score > max_score) { + max_score = score; + best_match = *argv; + } + + free(fdt); + } + + if (best_match && !all) + printf("%s\n", best_match); + + return 0; +}