// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/of.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
	u32	  flash_base;    // Address within FLASH of image
	u32	  mem_base;      // Address in memory where it executes
	u32	  size;          // Length of image
	u32	  entry_point;   // Execution entry point
	u32	  data_length;   // Length of actual data
	unsigned char _pad[256 - (16 + 7 * sizeof(u32))];
	u32	  desc_cksum;    // Checksum over image descriptor
	u32	  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 void parse_redboot_of(struct mtd_info *master)
{
	struct device_node *np;
	struct device_node *npart;
	u32 dirblock;
	int ret;

	np = mtd_get_of_node(master);
	if (!np)
		return;

	npart = of_get_child_by_name(np, "partitions");
	if (!npart)
		return;

	ret = of_property_read_u32(npart, "fis-index-block", &dirblock);
	of_node_put(npart);
	if (ret)
		return;

	/*
	 * Assign the block found in the device tree to the local
	 * directory block pointer.
	 */
	directory = dirblock;
}

static int parse_redboot_partitions(struct mtd_info *master,
				    const 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

	parse_redboot_of(master);

	if (directory < 0) {
		offset = master->size + directory * master->erasesize;
		while (mtd_block_isbad(master, offset)) {
			if (!offset) {
nogood:
				pr_notice("Failed to find a non-bad block to check for RedBoot partition table\n");
				return -EIO;
			}
			offset -= master->erasesize;
		}
	} else {
		offset = directory * master->erasesize;
		while (mtd_block_isbad(master, offset)) {
			offset += master->erasesize;
			if (offset == master->size)
				goto nogood;
		}
	}
	buf = vmalloc(master->erasesize);

	if (!buf)
		return -ENOMEM;

	pr_notice("Searching for RedBoot partition table in %s at offset 0x%lx\n",
		  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 */
		pr_notice("No RedBoot partition table detected in %s\n",
			  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;

		if (fl->next && fl->img->flash_base + fl->img->size + master->erasesize <= fl->next->img->flash_base) {
			if (!strcmp(parts[i].name, "rootfs")) {
				parts[i].size = fl->next->img->flash_base;
				parts[i].size &= ~(master->erasesize - 1);
				parts[i].size -= parts[i].offset;
#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
				nrparts--;
			} else {
				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 const struct of_device_id mtd_parser_redboot_of_match_table[] = {
	{ .compatible = "redboot-fis" },
	{},
};
MODULE_DEVICE_TABLE(of, mtd_parser_redboot_of_match_table);

static struct mtd_part_parser redboot_parser = {
	.parse_fn = parse_redboot_partitions,
	.name = "RedBoot",
	.of_match_table = mtd_parser_redboot_of_match_table,
};
module_mtd_part_parser(redboot_parser);

/* mtd parsers will request the module by parser name */
MODULE_ALIAS("RedBoot");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("Parsing code for RedBoot Flash Image System (FIS) tables");