cmdlinepart.c

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/*
 * Read flash partition table from command line
 *
 * Copyright © 2002      SYSGO Real-Time Solutions GmbH
 * Copyright © 2002-2010 David Woodhouse <[email protected]>
 *
 * 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
 *
 * The format for the command line is as follows:
 *
 * mtdparts=<mtddef>[;<mtddef]
 * <mtddef>  := <mtd-id>:<partdef>[,<partdef>]
 *              where <mtd-id> is the name from the "cat /proc/mtd" command
 * <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
 * <name>    := '(' NAME ')'
 *
 * 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)
 */

#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>

/* error message prefix */
#define ERRP "mtd: "

/* 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 UINT_MAX
#define OFFSET_CONTINUOUS UINT_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 *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 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 < PAGE_SIZE) {
            printk(KERN_ERR ERRP "partition size too small (%lx)\n", size);
            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) {
            printk(KERN_ERR ERRP "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) {
            printk(KERN_ERR ERRP "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 zero 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) {
            printk(KERN_ERR ERRP "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 != ';') {
            printk(KERN_ERR ERRP "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,
                    struct mtd_partition **pparts,
                    struct mtd_part_parser_data *data)
{
    unsigned 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;
    }

    for (part = partitions; part; part = part->next) {
        if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id))) {
            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 (part->parts[i].size == 0) {
                    printk(KERN_WARNING ERRP
                           "%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));
                    continue;
                }

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

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

            return part->num_parts;
        }
    }

    return 0;
}


/*
 * 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 mtdpart_setup(char *s)
{
    cmdline = s;
    return 1;
}

__setup("mtdparts=", mtdpart_setup);

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

static int __init cmdline_parser_init(void)
{
    return register_mtd_parser(&cmdline_parser);
}

module_init(cmdline_parser_init);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marius Groeger <[email protected]>");
MODULE_DESCRIPTION("Command line configuration of MTD partitions");