linux/drivers/mtd/cmdlinepart.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Read flash partition table from command line
 *
 * Copyright © 2002      SYSGO Real-Time Solutions GmbH
 * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * The format for the command line is as follows:
 *
 * mtdparts=<mtddef>[;<mtddef]
 * <mtddef>  := <mtd-id>:<partdef>[,<partdef>]
 * <partdef> := <size>[@<offset>][<name>][ro][lk]
 * <mtd-id>  := unique name used in mapping driver/device (mtd->name)
 * <size>    := standard linux memsize OR "-" to denote all remaining space
 *              size is automatically truncated at end of device
 *              if specified or truncated size is 0 the part is skipped
 * <offset>  := standard linux memsize
 *              if omitted the part will immediately follow the previous part
 *              or 0 if the first part
 * <name>    := '(' NAME ')'
 *              NAME will appear in /proc/mtd
 *
 * <size> and <offset> can be specified such that the parts are out of order
 * in physical memory and may even overlap.
 *
 * The parts are assigned MTD numbers in the order they are specified in the
 * command line regardless of their order in physical memory.
 *
 * Examples:
 *
 * 1 NOR Flash, with 1 single writable partition:
 * edb7312-nor:-
 *
 * 1 NOR Flash with 2 partitions, 1 NAND with one
 * edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)
 */

#define pr_fmt(fmt)	"mtd: " fmt

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/module.h>
#include <linux/err.h>

/* debug macro */
#if 0
#define dbg(x) do { printk("DEBUG-CMDLINE-PART: "); printk x; } while(0)
#else
#define dbg(x)
#endif


/* special size referring to all the remaining space in a partition */
#define SIZE_REMAINING ULLONG_MAX
#define OFFSET_CONTINUOUS ULLONG_MAX

struct cmdline_mtd_partition {
	struct cmdline_mtd_partition *next;
	char *mtd_id;
	int num_parts;
	struct mtd_partition *parts;
};

/* mtdpart_setup() parses into here */
static struct cmdline_mtd_partition *partitions;

/* the command line passed to mtdpart_setup() */
static char *mtdparts;
static char *cmdline;
static int cmdline_parsed;

/*
 * Parse one partition definition for an MTD. Since there can be many
 * comma separated partition definitions, this function calls itself
 * recursively until no more partition definitions are found. Nice side
 * effect: the memory to keep the mtd_partition structs and the names
 * is allocated upon the last definition being found. At that point the
 * syntax has been verified ok.
 */
static struct mtd_partition * newpart(char *s,
				      char **retptr,
				      int *num_parts,
				      int this_part,
				      unsigned char **extra_mem_ptr,
				      int extra_mem_size)
{
	struct mtd_partition *parts;
	unsigned long long size, offset = OFFSET_CONTINUOUS;
	char *name;
	int name_len;
	unsigned char *extra_mem;
	char delim;
	unsigned int mask_flags;

	/* fetch the partition size */
	if (*s == '-') {
		/* assign all remaining space to this partition */
		size = SIZE_REMAINING;
		s++;
	} else {
		size = memparse(s, &s);
		if (!size) {
			pr_err("partition has size 0\n");
			return ERR_PTR(-EINVAL);
		}
	}

	/* fetch partition name and flags */
	mask_flags = 0; /* this is going to be a regular partition */
	delim = 0;

	/* check for offset */
	if (*s == '@') {
		s++;
		offset = memparse(s, &s);
	}

	/* now look for name */
	if (*s == '(')
		delim = ')';

	if (delim) {
		char *p;

		name = ++s;
		p = strchr(name, delim);
		if (!p) {
			pr_err("no closing %c found in partition name\n", delim);
			return ERR_PTR(-EINVAL);
		}
		name_len = p - name;
		s = p + 1;
	} else {
		name = NULL;
		name_len = 13; /* Partition_000 */
	}

	/* record name length for memory allocation later */
	extra_mem_size += name_len + 1;

	/* test for options */
	if (strncmp(s, "ro", 2) == 0) {
		mask_flags |= MTD_WRITEABLE;
		s += 2;
	}

	/* if lk is found do NOT unlock the MTD partition*/
	if (strncmp(s, "lk", 2) == 0) {
		mask_flags |= MTD_POWERUP_LOCK;
		s += 2;
	}

	/* test if more partitions are following */
	if (*s == ',') {
		if (size == SIZE_REMAINING) {
			pr_err("no partitions allowed after a fill-up partition\n");
			return ERR_PTR(-EINVAL);
		}
		/* more partitions follow, parse them */
		parts = newpart(s + 1, &s, num_parts, this_part + 1,
				&extra_mem, extra_mem_size);
		if (IS_ERR(parts))
			return parts;
	} else {
		/* this is the last partition: allocate space for all */
		int alloc_size;

		*num_parts = this_part + 1;
		alloc_size = *num_parts * sizeof(struct mtd_partition) +
			     extra_mem_size;

		parts = kzalloc(alloc_size, GFP_KERNEL);
		if (!parts)
			return ERR_PTR(-ENOMEM);
		extra_mem = (unsigned char *)(parts + *num_parts);
	}

	/*
	 * enter this partition (offset will be calculated later if it is
	 * OFFSET_CONTINUOUS at this point)
	 */
	parts[this_part].size = size;
	parts[this_part].offset = offset;
	parts[this_part].mask_flags = mask_flags;
	if (name)
		strlcpy(extra_mem, name, name_len + 1);
	else
		sprintf(extra_mem, "Partition_%03d", this_part);
	parts[this_part].name = extra_mem;
	extra_mem += name_len + 1;

	dbg(("partition %d: name <%s>, offset %llx, size %llx, mask flags %x\n",
	     this_part, parts[this_part].name, parts[this_part].offset,
	     parts[this_part].size, parts[this_part].mask_flags));

	/* return (updated) pointer to extra_mem memory */
	if (extra_mem_ptr)
		*extra_mem_ptr = extra_mem;

	/* return (updated) pointer command line string */
	*retptr = s;

	/* return partition table */
	return parts;
}

/*
 * Parse the command line.
 */
static int mtdpart_setup_real(char *s)
{
	cmdline_parsed = 1;

	for( ; s != NULL; )
	{
		struct cmdline_mtd_partition *this_mtd;
		struct mtd_partition *parts;
		int mtd_id_len, num_parts;
		char *p, *mtd_id;

		mtd_id = s;

		/* fetch <mtd-id> */
		p = strchr(s, ':');
		if (!p) {
			pr_err("no mtd-id\n");
			return -EINVAL;
		}
		mtd_id_len = p - mtd_id;

		dbg(("parsing <%s>\n", p+1));

		/*
		 * parse one mtd. have it reserve memory for the
		 * struct cmdline_mtd_partition and the mtd-id string.
		 */
		parts = newpart(p + 1,		/* cmdline */
				&s,		/* out: updated cmdline ptr */
				&num_parts,	/* out: number of parts */
				0,		/* first partition */
				(unsigned char**)&this_mtd, /* out: extra mem */
				mtd_id_len + 1 + sizeof(*this_mtd) +
				sizeof(void*)-1 /*alignment*/);
		if (IS_ERR(parts)) {
			/*
			 * An error occurred. We're either:
			 * a) out of memory, or
			 * b) in the middle of the partition spec
			 * Either way, this mtd is hosed and we're
			 * unlikely to succeed in parsing any more
			 */
			 return PTR_ERR(parts);
		 }

		/* align this_mtd */
		this_mtd = (struct cmdline_mtd_partition *)
				ALIGN((unsigned long)this_mtd, sizeof(void *));
		/* enter results */
		this_mtd->parts = parts;
		this_mtd->num_parts = num_parts;
		this_mtd->mtd_id = (char*)(this_mtd + 1);
		strlcpy(this_mtd->mtd_id, mtd_id, mtd_id_len + 1);

		/* link into chain */
		this_mtd->next = partitions;
		partitions = this_mtd;

		dbg(("mtdid=<%s> num_parts=<%d>\n",
		     this_mtd->mtd_id, this_mtd->num_parts));


		/* EOS - we're done */
		if (*s == 0)
			break;

		/* does another spec follow? */
		if (*s != ';') {
			pr_err("bad character after partition (%c)\n", *s);
			return -EINVAL;
		}
		s++;
	}

	return 0;
}

/*
 * Main function to be called from the MTD mapping driver/device to
 * obtain the partitioning information. At this point the command line
 * arguments will actually be parsed and turned to struct mtd_partition
 * information. It returns partitions for the requested mtd device, or
 * the first one in the chain if a NULL mtd_id is passed in.
 */
static int parse_cmdline_partitions(struct mtd_info *master,
				    const struct mtd_partition **pparts,
				    struct mtd_part_parser_data *data)
{
	unsigned long long offset;
	int i, err;
	struct cmdline_mtd_partition *part;
	const char *mtd_id = master->name;

	/* parse command line */
	if (!cmdline_parsed) {
		err = mtdpart_setup_real(cmdline);
		if (err)
			return err;
	}

	/*
	 * Search for the partition definition matching master->name.
	 * If master->name is not set, stop at first partition definition.
	 */
	for (part = partitions; part; part = part->next) {
		if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id)))
			break;
	}

	if (!part)
		return 0;

	for (i = 0, offset = 0; i < part->num_parts; i++) {
		if (part->parts[i].offset == OFFSET_CONTINUOUS)
			part->parts[i].offset = offset;
		else
			offset = part->parts[i].offset;

		if (part->parts[i].size == SIZE_REMAINING)
			part->parts[i].size = master->size - offset;

		if (offset + part->parts[i].size > master->size) {
			pr_warn("%s: partitioning exceeds flash size, truncating\n",
				part->mtd_id);
			part->parts[i].size = master->size - offset;
		}
		offset += part->parts[i].size;

		if (part->parts[i].size == 0) {
			pr_warn("%s: skipping zero sized partition\n",
				part->mtd_id);
			part->num_parts--;
			memmove(&part->parts[i], &part->parts[i + 1],
				sizeof(*part->parts) * (part->num_parts - i));
			i--;
		}
	}

	*pparts = kmemdup(part->parts, sizeof(*part->parts) * part->num_parts,
			  GFP_KERNEL);
	if (!*pparts)
		return -ENOMEM;

	return part->num_parts;
}


/*
 * This is the handler for our kernel parameter, called from
 * main.c::checksetup(). Note that we can not yet kmalloc() anything,
 * so we only save the commandline for later processing.
 *
 * This function needs to be visible for bootloaders.
 */
static int __init mtdpart_setup(char *s)
{
	cmdline = s;
	return 1;
}

__setup("mtdparts=", mtdpart_setup);

static struct mtd_part_parser cmdline_parser = {
	.parse_fn = parse_cmdline_partitions,
	.name = "cmdlinepart",
};

static int __init cmdline_parser_init(void)
{
	if (mtdparts)
		mtdpart_setup(mtdparts);
	register_mtd_parser(&cmdline_parser);
	return 0;
}

static void __exit cmdline_parser_exit(void)
{
	deregister_mtd_parser(&cmdline_parser);
}

module_init(cmdline_parser_init);
module_exit(cmdline_parser_exit);

MODULE_PARM_DESC(mtdparts, "Partitioning specification");
module_param(mtdparts, charp, 0);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marius Groeger <mag@sysgo.de>");
MODULE_DESCRIPTION("Command line configuration of MTD partitions");