// SPDX-License-Identifier: GPL-2.0-or-later
/* sbc_gxx.c -- MTD map driver for Arcom Control Systems SBC-MediaGX,
                SBC-GXm and SBC-GX1 series boards.

   Copyright (C) 2001 Arcom Control System Ltd


The SBC-MediaGX / SBC-GXx has up to 16 MiB of
Intel StrataFlash (28F320/28F640) in x8 mode.

This driver uses the CFI probe and Intel Extended Command Set drivers.

The flash is accessed as follows:

   16 KiB memory window at 0xdc000-0xdffff

   Two IO address locations for paging

   0x258
       bit 0-7: address bit 14-21
   0x259
       bit 0-1: address bit 22-23
       bit 7:   0 - reset/powered down
                1 - device enabled

The single flash device is divided into 3 partition which appear as
separate MTD devices.

25/04/2001 AJL (Arcom)  Modified signon strings and partition sizes
                        (to support bzImages up to 638KiB-ish)
*/

// Includes

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

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

// Defines

// - Hardware specific

#define WINDOW_START 0xdc000

/* Number of bits in offset. */
#define WINDOW_SHIFT 14
#define WINDOW_LENGTH (1 << WINDOW_SHIFT)

/* The bits for the offset into the window. */
#define WINDOW_MASK (WINDOW_LENGTH-1)
#define PAGE_IO 0x258
#define PAGE_IO_SIZE 2

/* bit 7 of 0x259 must be 1 to enable device. */
#define DEVICE_ENABLE 0x8000

// - Flash / Partition sizing

#define MAX_SIZE_KiB             16384
#define BOOT_PARTITION_SIZE_KiB  768
#define DATA_PARTITION_SIZE_KiB  1280
#define APP_PARTITION_SIZE_KiB   6144

// Globals

static volatile int page_in_window = -1; // Current page in window.
static void __iomem *iomapadr;
static DEFINE_SPINLOCK(sbc_gxx_spin);

/* partition_info gives details on the logical partitions that the split the
 * single flash device into. If the size if zero we use up to the end of the
 * device. */
static const struct mtd_partition partition_info[] = {
    { .name = "SBC-GXx flash boot partition",
      .offset = 0,
      .size =   BOOT_PARTITION_SIZE_KiB*1024 },
    { .name = "SBC-GXx flash data partition",
      .offset = BOOT_PARTITION_SIZE_KiB*1024,
      .size = (DATA_PARTITION_SIZE_KiB)*1024 },
    { .name = "SBC-GXx flash application partition",
      .offset = (BOOT_PARTITION_SIZE_KiB+DATA_PARTITION_SIZE_KiB)*1024 }
};

#define NUM_PARTITIONS 3

static inline void sbc_gxx_page(struct map_info *map, unsigned long ofs)
{
        unsigned long page = ofs >> WINDOW_SHIFT;

        if( page!=page_in_window ) {
                outw( page | DEVICE_ENABLE, PAGE_IO );
                page_in_window = page;
        }
}


static map_word sbc_gxx_read8(struct map_info *map, unsigned long ofs)
{
        map_word ret;
        spin_lock(&sbc_gxx_spin);
        sbc_gxx_page(map, ofs);
        ret.x[0] = readb(iomapadr + (ofs & WINDOW_MASK));
        spin_unlock(&sbc_gxx_spin);
        return ret;
}

static void sbc_gxx_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(&sbc_gxx_spin);
                sbc_gxx_page(map, from);
                memcpy_fromio(to, iomapadr + (from & WINDOW_MASK), thislen);
                spin_unlock(&sbc_gxx_spin);
                to += thislen;
                from += thislen;
                len -= thislen;
        }
}

static void sbc_gxx_write8(struct map_info *map, map_word d, unsigned long adr)
{
        spin_lock(&sbc_gxx_spin);
        sbc_gxx_page(map, adr);
        writeb(d.x[0], iomapadr + (adr & WINDOW_MASK));
        spin_unlock(&sbc_gxx_spin);
}

static void sbc_gxx_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(&sbc_gxx_spin);
                sbc_gxx_page(map, to);
                memcpy_toio(iomapadr + (to & WINDOW_MASK), from, thislen);
                spin_unlock(&sbc_gxx_spin);
                to += thislen;
                from += thislen;
                len -= thislen;
        }
}

static struct map_info sbc_gxx_map = {
        .name = "SBC-GXx flash",
        .phys = NO_XIP,
        .size = MAX_SIZE_KiB*1024, /* this must be set to a maximum possible amount
                         of flash so the cfi probe routines find all
                         the chips */
        .bankwidth = 1,
        .read = sbc_gxx_read8,
        .copy_from = sbc_gxx_copy_from,
        .write = sbc_gxx_write8,
        .copy_to = sbc_gxx_copy_to
};

/* MTD device for all of the flash. */
static struct mtd_info *all_mtd;

static void cleanup_sbc_gxx(void)
{
        if( all_mtd ) {
                mtd_device_unregister(all_mtd);
                map_destroy( all_mtd );
        }

        iounmap(iomapadr);
        release_region(PAGE_IO,PAGE_IO_SIZE);
}

static int __init init_sbc_gxx(void)
{
        iomapadr = ioremap(WINDOW_START, WINDOW_LENGTH);
        if (!iomapadr) {
                printk( KERN_ERR"%s: failed to ioremap memory region\n",
                        sbc_gxx_map.name );
                return -EIO;
        }

        if (!request_region( PAGE_IO, PAGE_IO_SIZE, "SBC-GXx flash")) {
                printk( KERN_ERR"%s: IO ports 0x%x-0x%x in use\n",
                        sbc_gxx_map.name,
                        PAGE_IO, PAGE_IO+PAGE_IO_SIZE-1 );
                iounmap(iomapadr);
                return -EAGAIN;
        }


        printk( KERN_INFO"%s: IO:0x%x-0x%x MEM:0x%x-0x%x\n",
                sbc_gxx_map.name,
                PAGE_IO, PAGE_IO+PAGE_IO_SIZE-1,
                WINDOW_START, WINDOW_START+WINDOW_LENGTH-1 );

        /* Probe for chip. */
        all_mtd = do_map_probe( "cfi_probe", &sbc_gxx_map );
        if( !all_mtd ) {
                cleanup_sbc_gxx();
                return -ENXIO;
        }

        all_mtd->owner = THIS_MODULE;

        /* Create MTD devices for each partition. */
        mtd_device_register(all_mtd, partition_info, NUM_PARTITIONS);

        return 0;
}

module_init(init_sbc_gxx);
module_exit(cleanup_sbc_gxx);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arcom Control Systems Ltd.");
MODULE_DESCRIPTION("MTD map driver for SBC-GXm and SBC-GX1 series boards");