axisflashmap.c

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/*
 * Physical mapping layer for MTD using the Axis partitiontable format
 *
 * Copyright (c) 2001, 2002 Axis Communications AB
 *
 * This file is under the GPL.
 *
 * First partition is always sector 0 regardless of if we find a partitiontable
 * or not. In the start of the next sector, there can be a partitiontable that
 * tells us what other partitions to define. If there isn't, we use a default
 * partition split defined below.
 *
 */

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

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

#include <asm/axisflashmap.h>
#include <asm/mmu.h>
#include <arch/sv_addr_ag.h>

#ifdef CONFIG_CRIS_LOW_MAP
#define FLASH_UNCACHED_ADDR  KSEG_8
#define FLASH_CACHED_ADDR    KSEG_5
#else
#define FLASH_UNCACHED_ADDR  KSEG_E
#define FLASH_CACHED_ADDR    KSEG_F
#endif

#if CONFIG_ETRAX_FLASH_BUSWIDTH==1
#define flash_data __u8
#elif CONFIG_ETRAX_FLASH_BUSWIDTH==2
#define flash_data __u16
#elif CONFIG_ETRAX_FLASH_BUSWIDTH==4
#define flash_data __u32
#endif

/* From head.S */
extern unsigned long romfs_start, romfs_length, romfs_in_flash;

/* The master mtd for the entire flash. */
struct mtd_info* axisflash_mtd = NULL;

/* Map driver functions. */

static map_word flash_read(struct map_info *map, unsigned long ofs)
{
    map_word tmp;
    tmp.x[0] = *(flash_data *)(map->map_priv_1 + ofs);
    return tmp;
}

static void flash_copy_from(struct map_info *map, void *to,
                unsigned long from, ssize_t len)
{
    memcpy(to, (void *)(map->map_priv_1 + from), len);
}

static void flash_write(struct map_info *map, map_word d, unsigned long adr)
{
    *(flash_data *)(map->map_priv_1 + adr) = (flash_data)d.x[0];
}

/*
 * The map for chip select e0.
 *
 * We run into tricky coherence situations if we mix cached with uncached
 * accesses to we only use the uncached version here.
 *
 * The size field is the total size where the flash chips may be mapped on the
 * chip select. MTD probes should find all devices there and it does not matter
 * if there are unmapped gaps or aliases (mirrors of flash devices). The MTD
 * probes will ignore them.
 *
 * The start address in map_priv_1 is in virtual memory so we cannot use
 * MEM_CSE0_START but must rely on that FLASH_UNCACHED_ADDR is the start
 * address of cse0.
 */
static struct map_info map_cse0 = {
    .name = "cse0",
    .size = MEM_CSE0_SIZE,
    .bankwidth = CONFIG_ETRAX_FLASH_BUSWIDTH,
    .read = flash_read,
    .copy_from = flash_copy_from,
    .write = flash_write,
    .map_priv_1 = FLASH_UNCACHED_ADDR
};

/*
 * The map for chip select e1.
 *
 * If there was a gap between cse0 and cse1, map_priv_1 would get the wrong
 * address, but there isn't.
 */
static struct map_info map_cse1 = {
    .name = "cse1",
    .size = MEM_CSE1_SIZE,
    .bankwidth = CONFIG_ETRAX_FLASH_BUSWIDTH,
    .read = flash_read,
    .copy_from = flash_copy_from,
    .write = flash_write,
    .map_priv_1 = FLASH_UNCACHED_ADDR + MEM_CSE0_SIZE
};

/* If no partition-table was found, we use this default-set. */
#define MAX_PARTITIONS         7
#define NUM_DEFAULT_PARTITIONS 3

/*
 * Default flash size is 2MB. CONFIG_ETRAX_PTABLE_SECTOR is most likely the
 * size of one flash block and "filesystem"-partition needs 5 blocks to be able
 * to use JFFS.
 */
static struct mtd_partition axis_default_partitions[NUM_DEFAULT_PARTITIONS] = {
    {
        .name = "boot firmware",
        .size = CONFIG_ETRAX_PTABLE_SECTOR,
        .offset = 0
    },
    {
        .name = "kernel",
        .size = 0x200000 - (6 * CONFIG_ETRAX_PTABLE_SECTOR),
        .offset = CONFIG_ETRAX_PTABLE_SECTOR
    },
    {
        .name = "filesystem",
        .size = 5 * CONFIG_ETRAX_PTABLE_SECTOR,
        .offset = 0x200000 - (5 * CONFIG_ETRAX_PTABLE_SECTOR)
    }
};

/* Initialize the ones normally used. */
static struct mtd_partition axis_partitions[MAX_PARTITIONS] = {
    {
        .name = "part0",
        .size = CONFIG_ETRAX_PTABLE_SECTOR,
        .offset = 0
    },
    {
        .name = "part1",
        .size = 0,
        .offset = 0
    },
    {
        .name = "part2",
        .size = 0,
        .offset = 0
    },
    {
        .name = "part3",
        .size = 0,
        .offset = 0
    },
    {
        .name = "part4",
        .size = 0,
        .offset = 0
    },
    {
        .name = "part5",
        .size = 0,
        .offset = 0
    },
    {
        .name = "part6",
        .size = 0,
        .offset = 0
    },
};

#ifdef CONFIG_ETRAX_AXISFLASHMAP_MTD0WHOLE
/* Main flash device */
static struct mtd_partition main_partition = {
    .name = "main",
    .size = 0,
    .offset = 0
};
#endif

/*
 * Probe a chip select for AMD-compatible (JEDEC) or CFI-compatible flash
 * chips in that order (because the amd_flash-driver is faster).
 */
static struct mtd_info *probe_cs(struct map_info *map_cs)
{
    struct mtd_info *mtd_cs = NULL;

    printk(KERN_INFO
               "%s: Probing a 0x%08lx bytes large window at 0x%08lx.\n",
           map_cs->name, map_cs->size, map_cs->map_priv_1);

#ifdef CONFIG_MTD_CFI
    mtd_cs = do_map_probe("cfi_probe", map_cs);
#endif
#ifdef CONFIG_MTD_JEDECPROBE
    if (!mtd_cs)
        mtd_cs = do_map_probe("jedec_probe", map_cs);
#endif

    return mtd_cs;
}

/*
 * Probe each chip select individually for flash chips. If there are chips on
 * both cse0 and cse1, the mtd_info structs will be concatenated to one struct
 * so that MTD partitions can cross chip boundries.
 *
 * The only known restriction to how you can mount your chips is that each
 * chip select must hold similar flash chips. But you need external hardware
 * to do that anyway and you can put totally different chips on cse0 and cse1
 * so it isn't really much of a restriction.
 */
static struct mtd_info *flash_probe(void)
{
    struct mtd_info *mtd_cse0;
    struct mtd_info *mtd_cse1;
    struct mtd_info *mtd_cse;

    mtd_cse0 = probe_cs(&map_cse0);
    mtd_cse1 = probe_cs(&map_cse1);

    if (!mtd_cse0 && !mtd_cse1) {
        /* No chip found. */
        return NULL;
    }

    if (mtd_cse0 && mtd_cse1) {
        struct mtd_info *mtds[] = { mtd_cse0, mtd_cse1 };

        /* Since the concatenation layer adds a small overhead we
         * could try to figure out if the chips in cse0 and cse1 are
         * identical and reprobe the whole cse0+cse1 window. But since
         * flash chips are slow, the overhead is relatively small.
         * So we use the MTD concatenation layer instead of further
         * complicating the probing procedure.
         */
        mtd_cse = mtd_concat_create(mtds, ARRAY_SIZE(mtds),
                        "cse0+cse1");
        if (!mtd_cse) {
            printk(KERN_ERR "%s and %s: Concatenation failed!\n",
                   map_cse0.name, map_cse1.name);

            /* The best we can do now is to only use what we found
             * at cse0.
             */
            mtd_cse = mtd_cse0;
            map_destroy(mtd_cse1);
        }
    } else {
        mtd_cse = mtd_cse0? mtd_cse0 : mtd_cse1;
    }

    return mtd_cse;
}

/*
 * Probe the flash chip(s) and, if it succeeds, read the partition-table
 * and register the partitions with MTD.
 */
static int __init init_axis_flash(void)
{
    struct mtd_info *mymtd;
    int err = 0;
    int pidx = 0;
    struct partitiontable_head *ptable_head = NULL;
    struct partitiontable_entry *ptable;
    int use_default_ptable = 1; /* Until proven otherwise. */
    const char pmsg[] = "  /dev/flash%d at 0x%08x, size 0x%08x\n";

    if (!(mymtd = flash_probe())) {
        /* There's no reason to use this module if no flash chip can
         * be identified. Make sure that's understood.
         */
        printk(KERN_INFO "axisflashmap: Found no flash chip.\n");
    } else {
        printk(KERN_INFO "%s: 0x%08x bytes of flash memory.\n",
               mymtd->name, mymtd->size);
        axisflash_mtd = mymtd;
    }

    if (mymtd) {
        mymtd->owner = THIS_MODULE;
        ptable_head = (struct partitiontable_head *)(FLASH_CACHED_ADDR +
                  CONFIG_ETRAX_PTABLE_SECTOR +
                  PARTITION_TABLE_OFFSET);
    }
    pidx++;  /* First partition is always set to the default. */

    if (ptable_head && (ptable_head->magic == PARTITION_TABLE_MAGIC)
        && (ptable_head->size <
        (MAX_PARTITIONS * sizeof(struct partitiontable_entry) +
        PARTITIONTABLE_END_MARKER_SIZE))
        && (*(unsigned long*)((void*)ptable_head + sizeof(*ptable_head) +
                  ptable_head->size -
                  PARTITIONTABLE_END_MARKER_SIZE)
        == PARTITIONTABLE_END_MARKER)) {
        /* Looks like a start, sane length and end of a
         * partition table, lets check csum etc.
         */
        int ptable_ok = 0;
        struct partitiontable_entry *max_addr =
            (struct partitiontable_entry *)
            ((unsigned long)ptable_head + sizeof(*ptable_head) +
             ptable_head->size);
        unsigned long offset = CONFIG_ETRAX_PTABLE_SECTOR;
        unsigned char *p;
        unsigned long csum = 0;

        ptable = (struct partitiontable_entry *)
            ((unsigned long)ptable_head + sizeof(*ptable_head));

        /* Lets be PARANOID, and check the checksum. */
        p = (unsigned char*) ptable;

        while (p <= (unsigned char*)max_addr) {
            csum += *p++;
            csum += *p++;
            csum += *p++;
            csum += *p++;
        }
        ptable_ok = (csum == ptable_head->checksum);

        /* Read the entries and use/show the info.  */
        printk(KERN_INFO " Found a%s partition table at 0x%p-0x%p.\n",
               (ptable_ok ? " valid" : "n invalid"), ptable_head,
               max_addr);

        /* We have found a working bootblock.  Now read the
         * partition table.  Scan the table.  It ends when
         * there is 0xffffffff, that is, empty flash.
         */
        while (ptable_ok
               && ptable->offset != 0xffffffff
               && ptable < max_addr
               && pidx < MAX_PARTITIONS) {

            axis_partitions[pidx].offset = offset + ptable->offset;
            axis_partitions[pidx].size = ptable->size;

            printk(pmsg, pidx, axis_partitions[pidx].offset,
                   axis_partitions[pidx].size);
            pidx++;
            ptable++;
        }
        use_default_ptable = !ptable_ok;
    }

    if (romfs_in_flash) {
        /* Add an overlapping device for the root partition (romfs). */

        axis_partitions[pidx].name = "romfs";
        axis_partitions[pidx].size = romfs_length;
        axis_partitions[pidx].offset = romfs_start - FLASH_CACHED_ADDR;
        axis_partitions[pidx].mask_flags |= MTD_WRITEABLE;

        printk(KERN_INFO
                       " Adding readonly flash partition for romfs image:\n");
        printk(pmsg, pidx, axis_partitions[pidx].offset,
               axis_partitions[pidx].size);
        pidx++;
    }

#ifdef CONFIG_ETRAX_AXISFLASHMAP_MTD0WHOLE
    if (mymtd) {
        main_partition.size = mymtd->size;
        err = mtd_device_register(mymtd, &main_partition, 1);
        if (err)
            panic("axisflashmap: Could not initialize "
                  "partition for whole main mtd device!\n");
    }
#endif

        if (mymtd) {
        if (use_default_ptable) {
            printk(KERN_INFO " Using default partition table.\n");
            err = mtd_device_register(mymtd,
                          axis_default_partitions,
                          NUM_DEFAULT_PARTITIONS);
        } else {
            err = mtd_device_register(mymtd, axis_partitions,
                          pidx);
        }

        if (err)
            panic("axisflashmap could not add MTD partitions!\n");
    }

    if (!romfs_in_flash) {
        /* Create an RAM device for the root partition (romfs). */

#if !defined(CONFIG_MTD_MTDRAM) || (CONFIG_MTDRAM_TOTAL_SIZE != 0) || (CONFIG_MTDRAM_ABS_POS != 0)
        /* No use trying to boot this kernel from RAM. Panic! */
        printk(KERN_EMERG "axisflashmap: Cannot create an MTD RAM "
               "device due to kernel (mis)configuration!\n");
        panic("This kernel cannot boot from RAM!\n");
#else
        struct mtd_info *mtd_ram;

        mtd_ram = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
        if (!mtd_ram)
            panic("axisflashmap couldn't allocate memory for "
                  "mtd_info!\n");

        printk(KERN_INFO " Adding RAM partition for romfs image:\n");
        printk(pmsg, pidx, (unsigned)romfs_start,
            (unsigned)romfs_length);

        err = mtdram_init_device(mtd_ram,
            (void *)romfs_start,
            romfs_length,
            "romfs");
        if (err)
            panic("axisflashmap could not initialize MTD RAM "
                  "device!\n");
#endif
    }
    return err;
}

/* This adds the above to the kernels init-call chain. */
module_init(init_axis_flash);

EXPORT_SYMBOL(axisflash_mtd);