firmware-utils: bcm4908kernel: tool adding BCM4908 kernel header

BCM4908 CFE bootloader requires kernel to be prepended with a custom
header. This simple tool implements support for such headers.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

diff --git a/Makefile b/Makefile
index 6074ecc608d09f0deca9d9972b91e3dd2074e0d3..a8c6ab4f6510c51142a5258deedd8832fb9abb1d 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -27,6 +27,7 @@ define Host/Compile
        $(call cc,add_header)
        $(call cc,addpattern)
        $(call cc,asustrx)
+       $(call cc,bcm4908kernel,-Wall)
        $(call cc,buffalo-enc buffalo-lib,-Wall)
        $(call cc,buffalo-tag buffalo-lib,-Wall)
        $(call cc,buffalo-tftp buffalo-lib,-Wall)

diff --git a/src/bcm4908kernel.c b/src/bcm4908kernel.c
new file mode 100644 (file)
index 0000000..fc5b281
--- /dev/null
+++ b/src/bcm4908kernel.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <byteswap.h>
+#include <endian.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if !defined(__BYTE_ORDER)
+#error "Unknown byte order"
+#endif
+
+#if __BYTE_ORDER == __BIG_ENDIAN
+#define cpu_to_le32(x) bswap_32(x)
+#define le32_to_cpu(x) bswap_32(x)
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+#define cpu_to_le32(x) (x)
+#define le32_to_cpu(x) (x)
+#else
+#error "Unsupported endianness"
+#endif
+
+struct bcm4908kernel_header {
+       uint32_t unk1;
+       uint32_t unk2;
+       uint32_t length;
+       uint8_t magic[4];
+       uint32_t unused;
+};
+
+static void usage() {
+       printf("Usage:\n");
+       printf("\n");
+       printf("\t-i pathname\t\t\tinput kernel filepath\n");
+       printf("\t-o pathname\t\t\toutput kernel filepath\n");
+}
+
+int main(int argc, char **argv) {
+       struct bcm4908kernel_header header;
+       uint8_t buf[1024];
+       FILE *out = NULL;
+       FILE *in = NULL;
+       size_t length;
+       size_t bytes;
+       int err = 0;
+       char c;
+
+       if (argc >= 2 && !strcmp(argv[1], "-h")) {
+               usage();
+               return 0;
+       }
+
+       while ((c = getopt(argc, argv, "i:o:")) != -1) {
+               switch (c) {
+               case 'i':
+                       in = fopen(optarg, "r");
+                       break;
+               case 'o':
+                       out = fopen(optarg, "w+");
+                       break;
+               }
+       }
+
+       if (!in || !out) {
+               fprintf(stderr, "Failed to open input and/or output file\n");
+               usage();
+               return -EINVAL;
+       }
+
+       if (fread(&header, 1, sizeof(header), in) != sizeof(header)) {
+               fprintf(stderr, "Failed to read %zu bytes from input file\n", sizeof(header));
+               err = -EIO;
+               goto err_close;
+       }
+
+       if (!memcmp(header.magic, "BRCM", 4)) {
+               fprintf(stderr, "Input file already contains BCM4908 kernel header\n");
+               err = -EIO;
+               goto err_close;
+       }
+
+       err = fseek(out, sizeof(header), SEEK_SET);
+       if (err) {
+               err = -errno;
+               fprintf(stderr, "Failed to fseek(): %d\n", err);
+               goto err_close;
+       }
+
+       length = 0;
+       rewind(in);
+       while ((bytes = fread(buf, 1, sizeof(buf), in)) > 0) {
+               if (fwrite(buf, 1, bytes, out) != bytes) {
+                       fprintf(stderr, "Failed to write %zu B to the output file\n", bytes);
+                       err = -EIO;
+                       goto err_close;
+               }
+               length += bytes;
+       }
+
+       header.unk1 = cpu_to_le32(0x00080000);
+       header.unk2 = cpu_to_le32(0x00080000);
+       header.length = cpu_to_le32(length);
+       header.magic[0] = 'B';
+       header.magic[1] = 'R';
+       header.magic[2] = 'C';
+       header.magic[3] = 'M';
+       header.unused = 0;
+
+       fseek(out, 0, SEEK_SET);
+
+       if (fwrite(&header, 1, sizeof(header), out) != sizeof(header)) {
+               fprintf(stderr, "Failed to write header to the output file\n");
+               err = -EIO;
+               goto err_close;
+       }
+
+err_close:
+       fclose(out);
+       fclose(in);
+       return err;
+}