/*

   * Parse RedBoot-style Flash Image System (FIS) tables and
   * produce a Linux partition array to match.

   *
   * Copyright © 2001      Red Hat UK Limited
   * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *

   */
  
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/vmalloc.h>
  
  #include <linux/mtd/mtd.h>
  #include <linux/mtd/partitions.h>

  #include <linux/module.h>

  
  struct fis_image_desc {
      unsigned char name[16];      // Null terminated name

      uint32_t	  flash_base;    // Address within FLASH of image
      uint32_t	  mem_base;      // Address in memory where it executes
      uint32_t	  size;          // Length of image
      uint32_t	  entry_point;   // Execution entry point
      uint32_t	  data_length;   // Length of actual data
      unsigned char _pad[256-(16+7*sizeof(uint32_t))];
      uint32_t	  desc_cksum;    // Checksum over image descriptor
      uint32_t	  file_cksum;    // Checksum over image data

  };
  
  struct fis_list {
  	struct fis_image_desc *img;
  	struct fis_list *next;
  };
  
  static int directory = CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK;
  module_param(directory, int, 0);
  
  static inline int redboot_checksum(struct fis_image_desc *img)
  {
  	/* RedBoot doesn't actually write the desc_cksum field yet AFAICT */
  	return 1;
  }

  static int parse_redboot_partitions(struct mtd_info *master,

  				    struct mtd_partition **pparts,
  				    struct mtd_part_parser_data *data)

  {
  	int nrparts = 0;
  	struct fis_image_desc *buf;
  	struct mtd_partition *parts;
  	struct fis_list *fl = NULL, *tmp_fl;
  	int ret, i;
  	size_t retlen;
  	char *names;
  	char *nullname;
  	int namelen = 0;
  	int nulllen = 0;
  	int numslots;
  	unsigned long offset;
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
  	static char nullstring[] = "unallocated";
  #endif

  	if ( directory < 0 ) {
  		offset = master->size + directory * master->erasesize;

  		while (mtd_can_have_bb(master) &&

  		       mtd_block_isbad(master, offset)) {

  			if (!offset) {
  			nogood:
  				printk(KERN_NOTICE "Failed to find a non-bad block to check for RedBoot partition table
  ");
  				return -EIO;
  			}
  			offset -= master->erasesize;
  		}
  	} else {
  		offset = directory * master->erasesize;

  		while (mtd_can_have_bb(master) &&

  		       mtd_block_isbad(master, offset)) {

  			offset += master->erasesize;
  			if (offset == master->size)
  				goto nogood;
  		}
  	}

  	buf = vmalloc(master->erasesize);
  
  	if (!buf)
  		return -ENOMEM;

  	printk(KERN_NOTICE "Searching for RedBoot partition table in %s at offset 0x%lx
  ",
  	       master->name, offset);

  	ret = mtd_read(master, offset, master->erasesize, &retlen,
  		       (void *)buf);

  
  	if (ret)
  		goto out;
  
  	if (retlen != master->erasesize) {
  		ret = -EIO;
  		goto out;
  	}
  
  	numslots = (master->erasesize / sizeof(struct fis_image_desc));
  	for (i = 0; i < numslots; i++) {

  		if (!memcmp(buf[i].name, "FIS directory", 14)) {
  			/* This is apparently the FIS directory entry for the
  			 * FIS directory itself.  The FIS directory size is

  			 * one erase block; if the buf[i].size field is

  			 * swab32(erasesize) then we know we are looking at
  			 * a byte swapped FIS directory - swap all the entries!

  			 * (NOTE: this is 'size' not 'data_length'; size is

  			 * the full size of the entry.)
  			 */

  
  			/* RedBoot can combine the FIS directory and
  			   config partitions into a single eraseblock;
  			   we assume wrong-endian if either the swapped
  			   'size' matches the eraseblock size precisely,
  			   or if the swapped size actually fits in an
  			   eraseblock while the unswapped size doesn't. */
  			if (swab32(buf[i].size) == master->erasesize ||
  			    (buf[i].size > master->erasesize
  			     && swab32(buf[i].size) < master->erasesize)) {

  				int j;

  				/* Update numslots based on actual FIS directory size */
  				numslots = swab32(buf[i].size) / sizeof (struct fis_image_desc);

  				for (j = 0; j < numslots; ++j) {
  
  					/* A single 0xff denotes a deleted entry.
  					 * Two of them in a row is the end of the table.
  					 */
  					if (buf[j].name[0] == 0xff) {
  				  		if (buf[j].name[1] == 0xff) {
  							break;
  						} else {
  							continue;
  						}
  					}

  					/* The unsigned long fields were written with the
  					 * wrong byte sex, name and pad have no byte sex.
  					 */

  					swab32s(&buf[j].flash_base);
  					swab32s(&buf[j].mem_base);
  					swab32s(&buf[j].size);
  					swab32s(&buf[j].entry_point);
  					swab32s(&buf[j].data_length);
  					swab32s(&buf[j].desc_cksum);
  					swab32s(&buf[j].file_cksum);

  				}

  			} else if (buf[i].size < master->erasesize) {

  				/* Update numslots based on actual FIS directory size */
  				numslots = buf[i].size / sizeof(struct fis_image_desc);

  			}

  			break;

  		}

  	}
  	if (i == numslots) {
  		/* Didn't find it */
  		printk(KERN_NOTICE "No RedBoot partition table detected in %s
  ",
  		       master->name);
  		ret = 0;
  		goto out;
  	}
  
  	for (i = 0; i < numslots; i++) {
  		struct fis_list *new_fl, **prev;

  		if (buf[i].name[0] == 0xff) {
  			if (buf[i].name[1] == 0xff) {
  				break;
  			} else {
  				continue;
  			}
  		}

  		if (!redboot_checksum(&buf[i]))
  			break;
  
  		new_fl = kmalloc(sizeof(struct fis_list), GFP_KERNEL);
  		namelen += strlen(buf[i].name)+1;
  		if (!new_fl) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		new_fl->img = &buf[i];

  		if (data && data->origin)
  			buf[i].flash_base -= data->origin;
  		else
  			buf[i].flash_base &= master->size-1;

  
  		/* I'm sure the JFFS2 code has done me permanent damage.
  		 * I now think the following is _normal_
  		 */
  		prev = &fl;
  		while(*prev && (*prev)->img->flash_base < new_fl->img->flash_base)
  			prev = &(*prev)->next;
  		new_fl->next = *prev;
  		*prev = new_fl;
  
  		nrparts++;
  	}
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
  	if (fl->img->flash_base) {
  		nrparts++;
  		nulllen = sizeof(nullstring);
  	}
  
  	for (tmp_fl = fl; tmp_fl->next; tmp_fl = tmp_fl->next) {
  		if (tmp_fl->img->flash_base + tmp_fl->img->size + master->erasesize <= tmp_fl->next->img->flash_base) {
  			nrparts++;
  			nulllen = sizeof(nullstring);
  		}
  	}
  #endif

  	parts = kzalloc(sizeof(*parts)*nrparts + nulllen + namelen, GFP_KERNEL);

  
  	if (!parts) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	nullname = (char *)&parts[nrparts];
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
  	if (nulllen > 0) {
  		strcpy(nullname, nullstring);
  	}
  #endif
  	names = nullname + nulllen;
  
  	i=0;
  
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
  	if (fl->img->flash_base) {
  	       parts[0].name = nullname;
  	       parts[0].size = fl->img->flash_base;
  	       parts[0].offset = 0;
  		i++;
  	}
  #endif
  	for ( ; i<nrparts; i++) {
  		parts[i].size = fl->img->size;
  		parts[i].offset = fl->img->flash_base;
  		parts[i].name = names;
  
  		strcpy(names, fl->img->name);
  #ifdef CONFIG_MTD_REDBOOT_PARTS_READONLY
  		if (!memcmp(names, "RedBoot", 8) ||
  				!memcmp(names, "RedBoot config", 15) ||
  				!memcmp(names, "FIS directory", 14)) {
  			parts[i].mask_flags = MTD_WRITEABLE;
  		}
  #endif
  		names += strlen(names)+1;
  
  #ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
  		if(fl->next && fl->img->flash_base + fl->img->size + master->erasesize <= fl->next->img->flash_base) {
  			i++;
  			parts[i].offset = parts[i-1].size + parts[i-1].offset;
  			parts[i].size = fl->next->img->flash_base - parts[i].offset;
  			parts[i].name = nullname;
  		}
  #endif
  		tmp_fl = fl;
  		fl = fl->next;
  		kfree(tmp_fl);
  	}
  	ret = nrparts;
  	*pparts = parts;
   out:
  	while (fl) {
  		struct fis_list *old = fl;
  		fl = fl->next;
  		kfree(old);
  	}
  	vfree(buf);
  	return ret;
  }
  
  static struct mtd_part_parser redboot_parser = {
  	.owner = THIS_MODULE,
  	.parse_fn = parse_redboot_partitions,
  	.name = "RedBoot",
  };

  /* mtd parsers will request the module by parser name */
  MODULE_ALIAS("RedBoot");

  static int __init redboot_parser_init(void)
  {
  	return register_mtd_parser(&redboot_parser);
  }
  
  static void __exit redboot_parser_exit(void)
  {
  	deregister_mtd_parser(&redboot_parser);
  }
  
  module_init(redboot_parser_init);
  module_exit(redboot_parser_exit);
  
  MODULE_LICENSE("GPL");

  MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");

  MODULE_DESCRIPTION("Parsing code for RedBoot Flash Image System (FIS) tables");