1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2012 Samsung Electronics
4 */
5
6#include <stdio.h>
7#include <stdlib.h>
8#include <unistd.h>
9#include <fcntl.h>
10#include <errno.h>
11#include <string.h>
12#include <sys/stat.h>
13#include <compiler.h>
14
15#define CHECKSUM_OFFSET		(14*1024-4)
16#define FILE_PERM		(S_IRUSR | S_IWUSR | S_IRGRP \
17				| S_IWGRP | S_IROTH | S_IWOTH)
18/*
19 * Requirement for the fixed size SPL header:
20 * IROM code reads first (CHECKSUM_OFFSET + 4) bytes from boot device. It then
21 * calculates the checksum of CHECKSUM_OFFSET bytes and compares with data at
22 * CHECKSUM_OFFSET location.
23 *
24 * Requirement for the variable size SPL header:
25
26 * IROM code reads the below header to find out the size of the blob (total
27 * size, header size included) and its checksum. Then it reads the rest of the
28 * blob [i.e size - sizeof(struct var_size_header) bytes], calculates the
29 * checksum and compares it with value read from the header.
30 */
31struct var_size_header {
32	uint32_t spl_size;
33	uint32_t spl_checksum;
34	uint32_t reserved[2];
35};
36
37static const char *prog_name;
38
39static void write_to_file(int ofd, void *buffer, int size)
40{
41	if (write(ofd, buffer, size) == size)
42		return;
43
44	fprintf(stderr, "%s: Failed to write to output file: %s\n",
45		prog_name, strerror(errno));
46	exit(EXIT_FAILURE);
47}
48
49/*
50 * The argv is expected to include one optional parameter and two filenames:
51 * [--vs] IN OUT
52 *
53 * --vs - turns on the variable size SPL mode
54 * IN  - the u-boot SPL binary, usually u-boot-spl.bin
55 * OUT - the prepared SPL blob, usually ${BOARD}-spl.bin
56 *
57 * This utility first reads the "u-boot-spl.bin" into a buffer. In case of
58 * fixed size SPL the buffer size is exactly CHECKSUM_OFFSET (such that
59 * smaller u-boot-spl.bin gets padded with 0xff bytes, the larger than limit
60 * u-boot-spl.bin causes an error). For variable size SPL the buffer size is
61 * eqaul to size of the IN file.
62 *
63 * Then it calculates checksum of the buffer by just summing up all bytes.
64 * Then
65 *
66 * - for fixed size SPL the buffer is written into the output file and the
67 *   checksum is appended to the file in little endian format, which results
68 *   in checksum added exactly at CHECKSUM_OFFSET.
69 *
70 * - for variable size SPL the checksum and file size are stored in the
71 *   var_size_header structure (again, in little endian format) and the
72 *   structure is written into the output file. Then the buffer is written
73 *   into the output file.
74 */
75int main(int argc, char **argv)
76{
77	unsigned char *buffer;
78	int i, ifd, ofd;
79	uint32_t checksum = 0;
80	off_t	len;
81	int	var_size_flag, read_size, count;
82	struct stat stat;
83	const int if_index = argc - 2; /* Input file name index in argv. */
84	const int of_index = argc - 1; /* Output file name index in argv. */
85
86	/* Strip path off the program name. */
87	prog_name = strrchr(argv[0], '/');
88	if (prog_name)
89		prog_name++;
90	else
91		prog_name = argv[0];
92
93	if ((argc < 3) ||
94	    (argc > 4) ||
95	    ((argc == 4) && strcmp(argv[1], "--vs"))) {
96		fprintf(stderr, "Usage: %s [--vs] <infile> <outfile>\n",
97			prog_name);
98		exit(EXIT_FAILURE);
99	}
100
101	/* four args mean variable size SPL wrapper is required */
102	var_size_flag = (argc == 4);
103
104	ifd = open(argv[if_index], O_RDONLY);
105	if (ifd < 0) {
106		fprintf(stderr, "%s: Can't open %s: %s\n",
107			prog_name, argv[if_index], strerror(errno));
108		exit(EXIT_FAILURE);
109	}
110
111	ofd = open(argv[of_index], O_WRONLY | O_CREAT | O_TRUNC, FILE_PERM);
112	if (ofd < 0) {
113		fprintf(stderr, "%s: Can't open %s: %s\n",
114			prog_name, argv[of_index], strerror(errno));
115		exit(EXIT_FAILURE);
116	}
117
118	if (fstat(ifd, &stat)) {
119		fprintf(stderr, "%s: Unable to get size of %s: %s\n",
120			prog_name, argv[if_index], strerror(errno));
121		exit(EXIT_FAILURE);
122	}
123
124	len = stat.st_size;
125
126	if (var_size_flag) {
127		read_size = len;
128		count = len;
129	} else {
130		if (len > CHECKSUM_OFFSET) {
131			fprintf(stderr,
132				"%s: %s is too big (exceeds %d bytes)\n",
133				prog_name, argv[if_index], CHECKSUM_OFFSET);
134			exit(EXIT_FAILURE);
135		}
136		count = CHECKSUM_OFFSET;
137		read_size = len;
138	}
139
140	buffer = malloc(count);
141	if (!buffer) {
142		fprintf(stderr,
143			"%s: Failed to allocate %d bytes to store %s\n",
144			prog_name, count, argv[if_index]);
145		exit(EXIT_FAILURE);
146	}
147
148	if (read(ifd, buffer, read_size) != read_size) {
149		fprintf(stderr, "%s: Can't read %s: %s\n",
150			prog_name, argv[if_index], strerror(errno));
151		exit(EXIT_FAILURE);
152	}
153
154	/* Pad if needed with 0xff to make flashing faster. */
155	if (read_size < count)
156		memset((char *)buffer + read_size, 0xff, count - read_size);
157
158	for (i = 0, checksum = 0; i < count; i++)
159		checksum += buffer[i];
160	checksum = cpu_to_le32(checksum);
161
162	if (var_size_flag) {
163		/* Prepare and write out the variable size SPL header. */
164		struct var_size_header vsh;
165		uint32_t spl_size;
166
167		memset(&vsh, 0, sizeof(vsh));
168		memcpy(&vsh.spl_checksum, &checksum, sizeof(checksum));
169
170		spl_size = cpu_to_le32(count + sizeof(struct var_size_header));
171		memcpy(&vsh.spl_size, &spl_size, sizeof(spl_size));
172		write_to_file(ofd, &vsh, sizeof(vsh));
173	}
174
175	write_to_file(ofd, buffer, count);
176
177	/* For fixed size SPL checksum is appended in the end. */
178	if (!var_size_flag)
179		write_to_file(ofd, &checksum, sizeof(checksum));
180
181	close(ifd);
182	close(ofd);
183	free(buffer);
184
185	return EXIT_SUCCESS;
186}
187