afs.c

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/*======================================================================

    drivers/mtd/afs.c: ARM Flash Layout/Partitioning

    Copyright © 2000 ARM Limited

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

   This is access code for flashes using ARM's flash partitioning
   standards.

======================================================================*/

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/init.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/partitions.h>

struct footer_struct {
    u32 image_info_base;    /* Address of first word of ImageFooter  */
    u32 image_start;    /* Start of area reserved by this footer */
    u32 signature;      /* 'Magic' number proves it's a footer   */
    u32 type;       /* Area type: ARM Image, SIB, customer   */
    u32 checksum;       /* Just this structure                   */
};

struct image_info_struct {
    u32 bootFlags;      /* Boot flags, compression etc.          */
    u32 imageNumber;    /* Unique number, selects for boot etc.  */
    u32 loadAddress;    /* Address program should be loaded to   */
    u32 length;     /* Actual size of image                  */
    u32 address;        /* Image is executed from here           */
    char name[16];      /* Null terminated                       */
    u32 headerBase;     /* Flash Address of any stripped header  */
    u32 header_length;  /* Length of header in memory            */
    u32 headerType;     /* AIF, RLF, s-record etc.               */
    u32 checksum;       /* Image checksum (inc. this struct)     */
};

static u32 word_sum(void *words, int num)
{
    u32 *p = words;
    u32 sum = 0;

    while (num--)
        sum += *p++;

    return sum;
}

static int
afs_read_footer(struct mtd_info *mtd, u_int *img_start, u_int *iis_start,
        u_int off, u_int mask)
{
    struct footer_struct fs;
    u_int ptr = off + mtd->erasesize - sizeof(fs);
    size_t sz;
    int ret;

    ret = mtd_read(mtd, ptr, sizeof(fs), &sz, (u_char *)&fs);
    if (ret >= 0 && sz != sizeof(fs))
        ret = -EINVAL;

    if (ret < 0) {
        printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
            ptr, ret);
        return ret;
    }

    ret = 1;

    /*
     * Does it contain the magic number?
     */
    if (fs.signature != 0xa0ffff9f)
        ret = 0;

    /*
     * Check the checksum.
     */
    if (word_sum(&fs, sizeof(fs) / sizeof(u32)) != 0xffffffff)
        ret = 0;

    /*
     * Don't touch the SIB.
     */
    if (fs.type == 2)
        ret = 0;

    *iis_start = fs.image_info_base & mask;
    *img_start = fs.image_start & mask;

    /*
     * Check the image info base.  This can not
     * be located after the footer structure.
     */
    if (*iis_start >= ptr)
        ret = 0;

    /*
     * Check the start of this image.  The image
     * data can not be located after this block.
     */
    if (*img_start > off)
        ret = 0;

    return ret;
}

static int
afs_read_iis(struct mtd_info *mtd, struct image_info_struct *iis, u_int ptr)
{
    size_t sz;
    int ret, i;

    memset(iis, 0, sizeof(*iis));
    ret = mtd_read(mtd, ptr, sizeof(*iis), &sz, (u_char *)iis);
    if (ret < 0)
        goto failed;

    if (sz != sizeof(*iis)) {
        ret = -EINVAL;
        goto failed;
    }

    ret = 0;

    /*
     * Validate the name - it must be NUL terminated.
     */
    for (i = 0; i < sizeof(iis->name); i++)
        if (iis->name[i] == '\0')
            break;

    if (i < sizeof(iis->name))
        ret = 1;

    return ret;

 failed:
    printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
        ptr, ret);
    return ret;
}

static int parse_afs_partitions(struct mtd_info *mtd,
                struct mtd_partition **pparts,
                struct mtd_part_parser_data *data)
{
    struct mtd_partition *parts;
    u_int mask, off, idx, sz;
    int ret = 0;
    char *str;

    /*
     * This is the address mask; we use this to mask off out of
     * range address bits.
     */
    mask = mtd->size - 1;

    /*
     * First, calculate the size of the array we need for the
     * partition information.  We include in this the size of
     * the strings.
     */
    for (idx = off = sz = 0; off < mtd->size; off += mtd->erasesize) {
        struct image_info_struct iis;
        u_int iis_ptr, img_ptr;

        ret = afs_read_footer(mtd, &img_ptr, &iis_ptr, off, mask);
        if (ret < 0)
            break;
        if (ret == 0)
            continue;

        ret = afs_read_iis(mtd, &iis, iis_ptr);
        if (ret < 0)
            break;
        if (ret == 0)
            continue;

        sz += sizeof(struct mtd_partition);
        sz += strlen(iis.name) + 1;
        idx += 1;
    }

    if (!sz)
        return ret;

    parts = kzalloc(sz, GFP_KERNEL);
    if (!parts)
        return -ENOMEM;

    str = (char *)(parts + idx);

    /*
     * Identify the partitions
     */
    for (idx = off = 0; off < mtd->size; off += mtd->erasesize) {
        struct image_info_struct iis;
        u_int iis_ptr, img_ptr;

        /* Read the footer. */
        ret = afs_read_footer(mtd, &img_ptr, &iis_ptr, off, mask);
        if (ret < 0)
            break;
        if (ret == 0)
            continue;

        /* Read the image info block */
        ret = afs_read_iis(mtd, &iis, iis_ptr);
        if (ret < 0)
            break;
        if (ret == 0)
            continue;

        strcpy(str, iis.name);

        parts[idx].name     = str;
        parts[idx].size     = (iis.length + mtd->erasesize - 1) & ~(mtd->erasesize - 1);
        parts[idx].offset   = img_ptr;
        parts[idx].mask_flags   = 0;

        printk("  mtd%d: at 0x%08x, %5lluKiB, %8u, %s\n",
            idx, img_ptr, parts[idx].size / 1024,
            iis.imageNumber, str);

        idx += 1;
        str = str + strlen(iis.name) + 1;
    }

    if (!idx) {
        kfree(parts);
        parts = NULL;
    }

    *pparts = parts;
    return idx ? idx : ret;
}

static struct mtd_part_parser afs_parser = {
    .owner = THIS_MODULE,
    .parse_fn = parse_afs_partitions,
    .name = "afs",
};

static int __init afs_parser_init(void)
{
    return register_mtd_parser(&afs_parser);
}

static void __exit afs_parser_exit(void)
{
    deregister_mtd_parser(&afs_parser);
}

module_init(afs_parser_init);
module_exit(afs_parser_exit);


MODULE_AUTHOR("ARM Ltd");
MODULE_DESCRIPTION("ARM Firmware Suite partition parser");
MODULE_LICENSE("GPL");