sc520cdp.c

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/* sc520cdp.c -- MTD map driver for AMD SC520 Customer Development Platform
 *
 * Copyright (C) 2001 Sysgo Real-Time Solutions GmbH
 *
 * 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
 *
 *
 * The SC520CDP is an evaluation board for the Elan SC520 processor available
 * from AMD. It has two banks of 32-bit Flash ROM, each 8 Megabytes in size,
 * and up to 512 KiB of 8-bit DIL Flash ROM.
 * For details see http://www.amd.com/products/epd/desiging/evalboards/18.elansc520/520_cdp_brief/index.html
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/concat.h>

/*
** The Embedded Systems BIOS decodes the first FLASH starting at
** 0x8400000. This is a *terrible* place for it because accessing
** the flash at this location causes the A22 address line to be high
** (that's what 0x8400000 binary's ought to be). But this is the highest
** order address line on the raw flash devices themselves!!
** This causes the top HALF of the flash to be accessed first. Beyond
** the physical limits of the flash, the flash chip aliases over (to
** 0x880000 which causes the bottom half to be accessed. This splits the
** flash into two and inverts it! If you then try to access this from another
** program that does NOT do this insanity, then you *will* access the
** first half of the flash, but not find what you expect there. That
** stuff is in the *second* half! Similarly, the address used by the
** BIOS for the second FLASH bank is also quite a bad choice.
** If REPROGRAM_PAR is defined below (the default), then this driver will
** choose more useful addresses for the FLASH banks by reprogramming the
** responsible PARxx registers in the SC520's MMCR region. This will
** cause the settings to be incompatible with the BIOS's settings, which
** shouldn't be a problem since you are running Linux, (i.e. the BIOS is
** not much use anyway). However, if you need to be compatible with
** the BIOS for some reason, just undefine REPROGRAM_PAR.
*/
#define REPROGRAM_PAR



#ifdef REPROGRAM_PAR

/* These are the addresses we want.. */
#define WINDOW_ADDR_0   0x08800000
#define WINDOW_ADDR_1   0x09000000
#define WINDOW_ADDR_2   0x09800000

/* .. and these are the addresses the BIOS gives us */
#define WINDOW_ADDR_0_BIOS  0x08400000
#define WINDOW_ADDR_1_BIOS  0x08c00000
#define WINDOW_ADDR_2_BIOS  0x09400000

#else

#define WINDOW_ADDR_0   0x08400000
#define WINDOW_ADDR_1   0x08C00000
#define WINDOW_ADDR_2   0x09400000

#endif

#define WINDOW_SIZE_0   0x00800000
#define WINDOW_SIZE_1   0x00800000
#define WINDOW_SIZE_2   0x00080000


static struct map_info sc520cdp_map[] = {
    {
        .name = "SC520CDP Flash Bank #0",
        .size = WINDOW_SIZE_0,
        .bankwidth = 4,
        .phys = WINDOW_ADDR_0
    },
    {
        .name = "SC520CDP Flash Bank #1",
        .size = WINDOW_SIZE_1,
        .bankwidth = 4,
        .phys = WINDOW_ADDR_1
    },
    {
        .name = "SC520CDP DIL Flash",
        .size = WINDOW_SIZE_2,
        .bankwidth = 1,
        .phys = WINDOW_ADDR_2
    },
};

#define NUM_FLASH_BANKS ARRAY_SIZE(sc520cdp_map)

static struct mtd_info *mymtd[NUM_FLASH_BANKS];
static struct mtd_info *merged_mtd;

#ifdef REPROGRAM_PAR

/*
** The SC520 MMCR (memory mapped control register) region resides
** at 0xFFFEF000. The 16 Programmable Address Region (PAR) registers
** are at offset 0x88 in the MMCR:
*/
#define SC520_MMCR_BASE     0xFFFEF000
#define SC520_MMCR_EXTENT   0x1000
#define SC520_PAR(x)        ((0x88/sizeof(unsigned long)) + (x))
#define NUM_SC520_PAR       16  /* total number of PAR registers */

/*
** The highest three bits in a PAR register determine what target
** device is controlled by this PAR. Here, only ROMCS? and BOOTCS
** devices are of interest.
*/
#define SC520_PAR_BOOTCS    (0x4<<29)
#define SC520_PAR_ROMCS0    (0x5<<29)
#define SC520_PAR_ROMCS1    (0x6<<29)
#define SC520_PAR_TRGDEV    (0x7<<29)

/*
** Bits 28 thru 26 determine some attributes for the
** region controlled by the PAR. (We only use non-cacheable)
*/
#define SC520_PAR_WRPROT    (1<<26) /* write protected       */
#define SC520_PAR_NOCACHE   (1<<27) /* non-cacheable         */
#define SC520_PAR_NOEXEC    (1<<28) /* code execution denied */


/*
** Bit 25 determines the granularity: 4K or 64K
*/
#define SC520_PAR_PG_SIZ4   (0<<25)
#define SC520_PAR_PG_SIZ64  (1<<25)

/*
** Build a value to be written into a PAR register.
** We only need ROM entries, 64K page size:
*/
#define SC520_PAR_ENTRY(trgdev, address, size) \
    ((trgdev) | SC520_PAR_NOCACHE | SC520_PAR_PG_SIZ64 | \
    (address) >> 16 | (((size) >> 16) - 1) << 14)

struct sc520_par_table
{
    unsigned long trgdev;
    unsigned long new_par;
    unsigned long default_address;
};

static const struct sc520_par_table par_table[NUM_FLASH_BANKS] =
{
    {   /* Flash Bank #0: selected by ROMCS0 */
        SC520_PAR_ROMCS0,
        SC520_PAR_ENTRY(SC520_PAR_ROMCS0, WINDOW_ADDR_0, WINDOW_SIZE_0),
        WINDOW_ADDR_0_BIOS
    },
    {   /* Flash Bank #1: selected by ROMCS1 */
        SC520_PAR_ROMCS1,
        SC520_PAR_ENTRY(SC520_PAR_ROMCS1, WINDOW_ADDR_1, WINDOW_SIZE_1),
        WINDOW_ADDR_1_BIOS
    },
    {   /* DIL (BIOS) Flash: selected by BOOTCS */
        SC520_PAR_BOOTCS,
        SC520_PAR_ENTRY(SC520_PAR_BOOTCS, WINDOW_ADDR_2, WINDOW_SIZE_2),
        WINDOW_ADDR_2_BIOS
    }
};


static void sc520cdp_setup_par(void)
{
    volatile unsigned long __iomem *mmcr;
    unsigned long mmcr_val;
    int i, j;

    /* map in SC520's MMCR area */
    mmcr = ioremap_nocache(SC520_MMCR_BASE, SC520_MMCR_EXTENT);
    if(!mmcr) { /* ioremap_nocache failed: skip the PAR reprogramming */
        /* force physical address fields to BIOS defaults: */
        for(i = 0; i < NUM_FLASH_BANKS; i++)
            sc520cdp_map[i].phys = par_table[i].default_address;
        return;
    }

    /*
    ** Find the PARxx registers that are responsible for activating
    ** ROMCS0, ROMCS1 and BOOTCS. Reprogram each of these with a
    ** new value from the table.
    */
    for(i = 0; i < NUM_FLASH_BANKS; i++) {      /* for each par_table entry  */
        for(j = 0; j < NUM_SC520_PAR; j++) {    /* for each PAR register     */
            mmcr_val = mmcr[SC520_PAR(j)];
            /* if target device field matches, reprogram the PAR */
            if((mmcr_val & SC520_PAR_TRGDEV) == par_table[i].trgdev)
            {
                mmcr[SC520_PAR(j)] = par_table[i].new_par;
                break;
            }
        }
        if(j == NUM_SC520_PAR)
        {   /* no matching PAR found: try default BIOS address */
            printk(KERN_NOTICE "Could not find PAR responsible for %s\n",
                sc520cdp_map[i].name);
            printk(KERN_NOTICE "Trying default address 0x%lx\n",
                par_table[i].default_address);
            sc520cdp_map[i].phys = par_table[i].default_address;
        }
    }
    iounmap(mmcr);
}
#endif


static int __init init_sc520cdp(void)
{
    int i, devices_found = 0;

#ifdef REPROGRAM_PAR
    /* reprogram PAR registers so flash appears at the desired addresses */
    sc520cdp_setup_par();
#endif

    for (i = 0; i < NUM_FLASH_BANKS; i++) {
        printk(KERN_NOTICE "SC520 CDP flash device: 0x%Lx at 0x%Lx\n",
            (unsigned long long)sc520cdp_map[i].size,
            (unsigned long long)sc520cdp_map[i].phys);

        sc520cdp_map[i].virt = ioremap_nocache(sc520cdp_map[i].phys, sc520cdp_map[i].size);

        if (!sc520cdp_map[i].virt) {
            printk("Failed to ioremap_nocache\n");
            return -EIO;
        }

        simple_map_init(&sc520cdp_map[i]);

        mymtd[i] = do_map_probe("cfi_probe", &sc520cdp_map[i]);
        if(!mymtd[i])
            mymtd[i] = do_map_probe("jedec_probe", &sc520cdp_map[i]);
        if(!mymtd[i])
            mymtd[i] = do_map_probe("map_rom", &sc520cdp_map[i]);

        if (mymtd[i]) {
            mymtd[i]->owner = THIS_MODULE;
            ++devices_found;
        }
        else {
            iounmap(sc520cdp_map[i].virt);
        }
    }
    if(devices_found >= 2) {
        /* Combine the two flash banks into a single MTD device & register it: */
        merged_mtd = mtd_concat_create(mymtd, 2, "SC520CDP Flash Banks #0 and #1");
        if(merged_mtd)
            mtd_device_register(merged_mtd, NULL, 0);
    }
    if(devices_found == 3) /* register the third (DIL-Flash) device */
        mtd_device_register(mymtd[2], NULL, 0);
    return(devices_found ? 0 : -ENXIO);
}

static void __exit cleanup_sc520cdp(void)
{
    int i;

    if (merged_mtd) {
        mtd_device_unregister(merged_mtd);
        mtd_concat_destroy(merged_mtd);
    }
    if (mymtd[2])
        mtd_device_unregister(mymtd[2]);

    for (i = 0; i < NUM_FLASH_BANKS; i++) {
        if (mymtd[i])
            map_destroy(mymtd[i]);
        if (sc520cdp_map[i].virt) {
            iounmap(sc520cdp_map[i].virt);
            sc520cdp_map[i].virt = NULL;
        }
    }
}

module_init(init_sc520cdp);
module_exit(cleanup_sc520cdp);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sysgo Real-Time Solutions GmbH");
MODULE_DESCRIPTION("MTD map driver for AMD SC520 Customer Development Platform");