/* ######################################################################

   Tempustech VMAX SBC301 MTD Driver.

   The VMAx 301 is a SBC based on . It
   comes with three builtin AMD 29F016B flash chips and a socket for SRAM or
   more flash. Each unit has it's own 8k mapping into a settable region
   (0xD8000). There are two 8k mappings for each MTD, the first is always set
   to the lower 8k of the device the second is paged. Writing a 16 bit page
   value to anywhere in the first 8k will cause the second 8k to page around.

   To boot the device a bios extension must be installed into the first 8k
   of flash that is smart enough to copy itself down, page in the rest of
   itself and begin executing.

   ##################################################################### */

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <asm/io.h>

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


#define WINDOW_START 0xd8000
#define WINDOW_LENGTH 0x2000
#define WINDOW_SHIFT 25
#define WINDOW_MASK 0x1FFF

/* Actually we could use two spinlocks, but we'd have to have
   more private space in the struct map_info. We lose a little
   performance like this, but we'd probably lose more by having
   the extra indirection from having one of the map->map_priv
   fields pointing to yet another private struct.
*/
static DEFINE_SPINLOCK(vmax301_spin);

static void __vmax301_page(struct map_info *map, unsigned long page)
{
        writew(page, map->map_priv_2 - WINDOW_LENGTH);
        map->map_priv_1 = page;
}

static inline void vmax301_page(struct map_info *map,
                                  unsigned long ofs)
{
        unsigned long page = (ofs >> WINDOW_SHIFT);
        if (map->map_priv_1 != page)
                __vmax301_page(map, page);
}

static map_word vmax301_read8(struct map_info *map, unsigned long ofs)
{
        map_word ret;
        spin_lock(&vmax301_spin);
        vmax301_page(map, ofs);
        ret.x[0] = readb(map->map_priv_2 + (ofs & WINDOW_MASK));
        spin_unlock(&vmax301_spin);
        return ret;
}

static void vmax301_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
{
        while(len) {
                unsigned long thislen = len;
                if (len > (WINDOW_LENGTH - (from & WINDOW_MASK)))
                        thislen = WINDOW_LENGTH-(from & WINDOW_MASK);
                spin_lock(&vmax301_spin);
                vmax301_page(map, from);
                memcpy_fromio(to, map->map_priv_2 + from, thislen);
                spin_unlock(&vmax301_spin);
                to += thislen;
                from += thislen;
                len -= thislen;
        }
}

static void vmax301_write8(struct map_info *map, map_word d, unsigned long adr)
{
        spin_lock(&vmax301_spin);
        vmax301_page(map, adr);
        writeb(d.x[0], map->map_priv_2 + (adr & WINDOW_MASK));
        spin_unlock(&vmax301_spin);
}

static void vmax301_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
{
        while(len) {
                unsigned long thislen = len;
                if (len > (WINDOW_LENGTH - (to & WINDOW_MASK)))
                        thislen = WINDOW_LENGTH-(to & WINDOW_MASK);

                spin_lock(&vmax301_spin);
                vmax301_page(map, to);
                memcpy_toio(map->map_priv_2 + to, from, thislen);
                spin_unlock(&vmax301_spin);
                to += thislen;
                from += thislen;
                len -= thislen;
        }
}

static struct map_info vmax_map[2] = {
        {
                .name = "VMAX301 Internal Flash",
                .phys = NO_XIP,
                .size = 3*2*1024*1024,
                .bankwidth = 1,
                .read = vmax301_read8,
                .copy_from = vmax301_copy_from,
                .write = vmax301_write8,
                .copy_to = vmax301_copy_to,
                .map_priv_1 = WINDOW_START + WINDOW_LENGTH,
                .map_priv_2 = 0xFFFFFFFF
        },
        {
                .name = "VMAX301 Socket",
                .phys = NO_XIP,
                .size = 0,
                .bankwidth = 1,
                .read = vmax301_read8,
                .copy_from = vmax301_copy_from,
                .write = vmax301_write8,
                .copy_to = vmax301_copy_to,
                .map_priv_1 = WINDOW_START + (3*WINDOW_LENGTH),
                .map_priv_2 = 0xFFFFFFFF
        }
};

static struct mtd_info *vmax_mtd[2] = {NULL, NULL};

static void __exit cleanup_vmax301(void)
{
        int i;

        for (i=0; i<2; i++) {
                if (vmax_mtd[i]) {
                        mtd_device_unregister(vmax_mtd[i]);
                        map_destroy(vmax_mtd[i]);
                }
        }
        iounmap((void *)vmax_map[0].map_priv_1 - WINDOW_START);
}

static int __init init_vmax301(void)
{
        int i;
        unsigned long iomapadr;
        // Print out our little header..
        printk("Tempustech VMAX 301 MEM:0x%x-0x%x\n",WINDOW_START,
               WINDOW_START+4*WINDOW_LENGTH);

        iomapadr = (unsigned long)ioremap(WINDOW_START, WINDOW_LENGTH*4);
        if (!iomapadr) {
                printk("Failed to ioremap memory region\n");
                return -EIO;
        }
        /* Put the address in the map's private data area.
           We store the actual MTD IO address rather than the
           address of the first half, because it's used more
           often.
        */
        vmax_map[0].map_priv_2 = iomapadr + WINDOW_START;
        vmax_map[1].map_priv_2 = iomapadr + (3*WINDOW_START);

        for (i=0; i<2; i++) {
                vmax_mtd[i] = do_map_probe("cfi_probe", &vmax_map[i]);
                if (!vmax_mtd[i])
                        vmax_mtd[i] = do_map_probe("jedec", &vmax_map[i]);
                if (!vmax_mtd[i])
                        vmax_mtd[i] = do_map_probe("map_ram", &vmax_map[i]);
                if (!vmax_mtd[i])
                        vmax_mtd[i] = do_map_probe("map_rom", &vmax_map[i]);
                if (vmax_mtd[i]) {
                        vmax_mtd[i]->owner = THIS_MODULE;
                        mtd_device_register(vmax_mtd[i], NULL, 0);
                }
        }

        if (!vmax_mtd[0] && !vmax_mtd[1]) {
                iounmap((void *)iomapadr);
                return -ENXIO;
        }

        return 0;
}

module_init(init_vmax301);
module_exit(cleanup_vmax301);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("MTD map driver for Tempustech VMAX SBC301 board");