Documentation/arm/SH-Mobile/vrl4.c

   1 /*
   2  * vrl4 format generator
   3  *
   4  * Copyright (C) 2010 Simon Horman
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 /*
  12  * usage: vrl4 < zImage > out
  13  *        dd if=out of=/dev/sdx bs=512 seek=1 # Write the image to sector 1
  14  *
  15  * Reads a zImage from stdin and writes a vrl4 image to stdout.
  16  * In practice this means writing a padded vrl4 header to stdout followed
  17  * by the zImage.
  18  *
  19  * The padding places the zImage at ALIGN bytes into the output.
  20  * The vrl4 uses ALIGN + START_BASE as the start_address.
  21  * This is where the mask ROM will jump to after verifying the header.
  22  *
  23  * The header sets copy_size to min(sizeof(zImage), MAX_BOOT_PROG_LEN) + ALIGN.
  24  * That is, the mask ROM will load the padded header (ALIGN bytes)
  25  * And then MAX_BOOT_PROG_LEN bytes of the image, or the entire image,
  26  * whichever is smaller.
  27  *
  28  * The zImage is not modified in any way.
  29  */
  30
  31 #define _BSD_SOURCE
  32 #include <endian.h>
  33 #include <unistd.h>
  34 #include <stdint.h>
  35 #include <stdio.h>
  36 #include <errno.h>
  37
  38 struct hdr {
  39         uint32_t magic1;
  40         uint32_t reserved1;
  41         uint32_t magic2;
  42         uint32_t reserved2;
  43         uint16_t copy_size;
  44         uint16_t boot_options;
  45         uint32_t reserved3;
  46         uint32_t start_address;
  47         uint32_t reserved4;
  48         uint32_t reserved5;
  49         char     reserved6[308];
  50 };
  51
  52 #define DECLARE_HDR(h)                                  \
  53         struct hdr (h) = {                              \
  54                 .magic1 =       htole32(0xea000000),    \
  55                 .reserved1 =    htole32(0x56),          \
  56                 .magic2 =       htole32(0xe59ff008),    \
  57                 .reserved3 =    htole16(0x1) }
  58
  59 /* Align to 512 bytes, the MMCIF sector size */
  60 #define ALIGN_BITS      9
  61 #define ALIGN           (1 << ALIGN_BITS)
  62
  63 #define START_BASE      0xe55b0000
  64
  65 /*
  66  * With an alignment of 512 the header uses the first sector.
  67  * There is a 128 sector (64kbyte) limit on the data loaded by the mask ROM.
  68  * So there are 127 sectors left for the boot programme. But in practice
  69  * Only a small portion of a zImage is needed, 16 sectors should be more
  70  * than enough.
  71  *
  72  * Note that this sets how much of the zImage is copied by the mask ROM.
  73  * The entire zImage is present after the header and is loaded
  74  * by the code in the boot program (which is the first portion of the zImage).
  75  */
  76 #define MAX_BOOT_PROG_LEN (16 * 512)
  77
  78 #define ROUND_UP(x)     ((x + ALIGN - 1) & ~(ALIGN - 1))
  79
  80 ssize_t do_read(int fd, void *buf, size_t count)
  81 {
  82         size_t offset = 0;
  83         ssize_t l;
  84
  85         while (offset < count) {
  86                 l = read(fd, buf + offset, count - offset);
  87                 if (!l)
  88                         break;
  89                 if (l < 0) {
  90                         if (errno == EAGAIN || errno == EWOULDBLOCK)
  91                                 continue;
  92                         perror("read");
  93                         return -1;
  94                 }
  95                 offset += l;
  96         }
  97
  98         return offset;
  99 }
 100
 101 ssize_t do_write(int fd, const void *buf, size_t count)
 102 {
 103         size_t offset = 0;
 104         ssize_t l;
 105
 106         while (offset < count) {
 107                 l = write(fd, buf + offset, count - offset);
 108                 if (l < 0) {
 109                         if (errno == EAGAIN || errno == EWOULDBLOCK)
 110                                 continue;
 111                         perror("write");
 112                         return -1;
 113                 }
 114                 offset += l;
 115         }
 116
 117         return offset;
 118 }
 119
 120 ssize_t write_zero(int fd, size_t len)
 121 {
 122         size_t i = len;
 123
 124         while (i--) {
 125                 const char x = 0;
 126                 if (do_write(fd, &x, 1) < 0)
 127                         return -1;
 128         }
 129
 130         return len;
 131 }
 132
 133 int main(void)
 134 {
 135         DECLARE_HDR(hdr);
 136         char boot_program[MAX_BOOT_PROG_LEN];
 137         size_t aligned_hdr_len, alligned_prog_len;
 138         ssize_t prog_len;
 139
 140         prog_len = do_read(0, boot_program, sizeof(boot_program));
 141         if (prog_len <= 0)
 142                 return -1;
 143
 144         aligned_hdr_len = ROUND_UP(sizeof(hdr));
 145         hdr.start_address = htole32(START_BASE + aligned_hdr_len);
 146         alligned_prog_len = ROUND_UP(prog_len);
 147         hdr.copy_size = htole16(aligned_hdr_len + alligned_prog_len);
 148
 149         if (do_write(1, &hdr, sizeof(hdr)) < 0)
 150                 return -1;
 151         if (write_zero(1, aligned_hdr_len - sizeof(hdr)) < 0)
 152                 return -1;
 153
 154         if (do_write(1, boot_program, prog_len) < 0)
 155                 return 1;
 156
 157         /* Write out the rest of the kernel */
 158         while (1) {
 159                 prog_len = do_read(0, boot_program, sizeof(boot_program));
 160                 if (prog_len < 0)
 161                         return 1;
 162                 if (prog_len == 0)
 163                         break;
 164                 if (do_write(1, boot_program, prog_len) < 0)
 165                         return 1;
 166         }
 167
 168         return 0;
 169 }