/*
   * (C) Copyright 2007-2011
   * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
   * Tom Cubie <tangliang@allwinnertech.com>
   *
   * a simple tool to generate bootable image for sunxi platform.
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  #include <fcntl.h>
  #include <stdio.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <string.h>
  #include <errno.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  
  /* boot head definition from sun4i boot code */
  struct boot_file_head {
  	uint32_t b_instruction;	/* one intruction jumping to real code */
  	uint8_t magic[8];	/* ="eGON.BT0" or "eGON.BT1", not C-style str */
  	uint32_t check_sum;	/* generated by PC */
  	uint32_t length;	/* generated by PC */
  	/*
  	 * We use a simplified header, only filling in what is needed
  	 * by the boot ROM. To be compatible with Allwinner tools we
  	 * would need to implement the proper fields here instead of
  	 * padding.
  	 */
  	uint8_t pad[12];		/* align to 32 bytes */
  };
  
  #define BOOT0_MAGIC                     "eGON.BT0"
  #define STAMP_VALUE                     0x5F0A6C39
  
  /* check sum functon from sun4i boot code */
  int gen_check_sum(struct boot_file_head *head_p)
  {
  	uint32_t length;
  	uint32_t *buf;
  	uint32_t loop;
  	uint32_t i;
  	uint32_t sum;
  
  	length = le32_to_cpu(head_p->length);
  	if ((length & 0x3) != 0)	/* must 4-byte-aligned */
  		return -1;
  	buf = (uint32_t *)head_p;
  	head_p->check_sum = cpu_to_le32(STAMP_VALUE);	/* fill stamp */
  	loop = length >> 2;
  
  	/* calculate the sum */
  	for (i = 0, sum = 0; i < loop; i++)
  		sum += le32_to_cpu(buf[i]);
  
  	/* write back check sum */
  	head_p->check_sum = cpu_to_le32(sum);
  
  	return 0;
  }
  
  #define ALIGN(x, a) __ALIGN_MASK((x), (typeof(x))(a)-1)
  #define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask))
  
  #define SUN4I_SRAM_SIZE 0x7600	/* 0x7748+ is used by BROM */
  #define SRAM_LOAD_MAX_SIZE (SUN4I_SRAM_SIZE - sizeof(struct boot_file_head))
  #define BLOCK_SIZE 512
  
  struct boot_img {
  	struct boot_file_head header;
  	char code[SRAM_LOAD_MAX_SIZE];
  	char pad[BLOCK_SIZE];
  };
  
  int main(int argc, char *argv[])
  {
  	int fd_in, fd_out;
  	struct boot_img img;
  	unsigned file_size;
  	int count;
  
  	if (argc < 2) {
  		printf("\tThis program makes an input bin file to sun4i " \
  		       "bootable image.
  " \
  		       "\tUsage: %s input_file out_putfile
  ", argv[0]);
  		return EXIT_FAILURE;
  	}
  
  	fd_in = open(argv[1], O_RDONLY);
  	if (fd_in < 0) {
  		perror("Open input file");
  		return EXIT_FAILURE;
  	}
  
  	memset(img.pad, 0, BLOCK_SIZE);
  
  	/* get input file size */
  	file_size = lseek(fd_in, 0, SEEK_END);
  
  	if (file_size > SRAM_LOAD_MAX_SIZE) {
  		fprintf(stderr, "ERROR: File too large!
  ");
  		return EXIT_FAILURE;
  	}
  
  	fd_out = open(argv[2], O_WRONLY | O_CREAT, 0666);
  	if (fd_out < 0) {
  		perror("Open output file");
  		return EXIT_FAILURE;
  	}
  
  	/* read file to buffer to calculate checksum */
  	lseek(fd_in, 0, SEEK_SET);
  	count = read(fd_in, img.code, file_size);
  	if (count != file_size) {
  		perror("Reading input image");
  		return EXIT_FAILURE;
  	}
  
  	/* fill the header */
  	img.header.b_instruction =	/* b instruction */
  		0xEA000000 |	/* jump to the first instr after the header */
  		((sizeof(struct boot_file_head) / sizeof(int) - 2)
  		 & 0x00FFFFFF);
  	memcpy(img.header.magic, BOOT0_MAGIC, 8);	/* no '0' termination */
  	img.header.length =
  		ALIGN(file_size + sizeof(struct boot_file_head), BLOCK_SIZE);
  	img.header.b_instruction = cpu_to_le32(img.header.b_instruction);
  	img.header.length = cpu_to_le32(img.header.length);
  	gen_check_sum(&img.header);
  
  	count = write(fd_out, &img, le32_to_cpu(img.header.length));
  	if (count != le32_to_cpu(img.header.length)) {
  		perror("Writing output");
  		return EXIT_FAILURE;
  	}
  
  	close(fd_in);
  	close(fd_out);
  
  	return EXIT_SUCCESS;
  }