// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/mtd/maps/ixp4xx.c
 *
 * MTD Map file for IXP4XX based systems. Please do not make per-board
 * changes in here. If your board needs special setup, do it in your
 * platform level code in arch/arm/mach-ixp4xx/board-setup.c
 *
 * Original Author: Intel Corporation
 * Maintainer: Deepak Saxena <dsaxena@mvista.com>
 *
 * Copyright (C) 2002 Intel Corporation
 * Copyright (C) 2003-2004 MontaVista Software, Inc.
 *
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/device.h>
#include <linux/platform_device.h>

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

#include <asm/io.h>
#include <asm/mach/flash.h>

#include <linux/reboot.h>

/*
 * Read/write a 16 bit word from flash address 'addr'.
 *
 * When the cpu is in little-endian mode it swizzles the address lines
 * ('address coherency') so we need to undo the swizzling to ensure commands
 * and the like end up on the correct flash address.
 *
 * To further complicate matters, due to the way the expansion bus controller
 * handles 32 bit reads, the byte stream ABCD is stored on the flash as:
 *     D15    D0
 *     +---+---+
 *     | A | B | 0
 *     +---+---+
 *     | C | D | 2
 *     +---+---+
 * This means that on LE systems each 16 bit word must be swapped. Note that
 * this requires CONFIG_MTD_CFI_BE_BYTE_SWAP to be enabled to 'unswap' the CFI
 * data and other flash commands which are always in D7-D0.
 */
#ifndef __ARMEB__
#ifndef CONFIG_MTD_CFI_BE_BYTE_SWAP
#  error CONFIG_MTD_CFI_BE_BYTE_SWAP required
#endif

static inline u16 flash_read16(void __iomem *addr)
{
        return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
}

static inline void flash_write16(u16 d, void __iomem *addr)
{
        __raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
}

#define BYTE0(h)        ((h) & 0xFF)
#define BYTE1(h)        (((h) >> 8) & 0xFF)

#else

static inline u16 flash_read16(const void __iomem *addr)
{
        return __raw_readw(addr);
}

static inline void flash_write16(u16 d, void __iomem *addr)
{
        __raw_writew(d, addr);
}

#define BYTE0(h)        (((h) >> 8) & 0xFF)
#define BYTE1(h)        ((h) & 0xFF)
#endif

static map_word ixp4xx_read16(struct map_info *map, unsigned long ofs)
{
        map_word val;
        val.x[0] = flash_read16(map->virt + ofs);
        return val;
}

/*
 * The IXP4xx expansion bus only allows 16-bit wide acceses
 * when attached to a 16-bit wide device (such as the 28F128J3A),
 * so we can't just memcpy_fromio().
 */
static void ixp4xx_copy_from(struct map_info *map, void *to,
                             unsigned long from, ssize_t len)
{
        u8 *dest = (u8 *) to;
        void __iomem *src = map->virt + from;

        if (len <= 0)
                return;

        if (from & 1) {
                *dest++ = BYTE1(flash_read16(src-1));
                src++;
                --len;
        }

        while (len >= 2) {
                u16 data = flash_read16(src);
                *dest++ = BYTE0(data);
                *dest++ = BYTE1(data);
                src += 2;
                len -= 2;
        }

        if (len > 0)
                *dest++ = BYTE0(flash_read16(src));
}

/*
 * Unaligned writes are ignored, causing the 8-bit
 * probe to fail and proceed to the 16-bit probe (which succeeds).
 */
static void ixp4xx_probe_write16(struct map_info *map, map_word d, unsigned long adr)
{
        if (!(adr & 1))
                flash_write16(d.x[0], map->virt + adr);
}

/*
 * Fast write16 function without the probing check above
 */
static void ixp4xx_write16(struct map_info *map, map_word d, unsigned long adr)
{
        flash_write16(d.x[0], map->virt + adr);
}

struct ixp4xx_flash_info {
        struct mtd_info *mtd;
        struct map_info map;
        struct resource *res;
};

static const char * const probes[] = { "RedBoot", "cmdlinepart", NULL };

static int ixp4xx_flash_remove(struct platform_device *dev)
{
        struct flash_platform_data *plat = dev_get_platdata(&dev->dev);
        struct ixp4xx_flash_info *info = platform_get_drvdata(dev);

        if(!info)
                return 0;

        if (info->mtd) {
                mtd_device_unregister(info->mtd);
                map_destroy(info->mtd);
        }

        if (plat->exit)
                plat->exit();

        return 0;
}

static int ixp4xx_flash_probe(struct platform_device *dev)
{
        struct flash_platform_data *plat = dev_get_platdata(&dev->dev);
        struct ixp4xx_flash_info *info;
        struct mtd_part_parser_data ppdata = {
                .origin = dev->resource->start,
        };
        int err = -1;

        if (!plat)
                return -ENODEV;

        if (plat->init) {
                err = plat->init();
                if (err)
                        return err;
        }

        info = devm_kzalloc(&dev->dev, sizeof(struct ixp4xx_flash_info),
                            GFP_KERNEL);
        if(!info) {
                err = -ENOMEM;
                goto Error;
        }

        platform_set_drvdata(dev, info);

        /*
         * Tell the MTD layer we're not 1:1 mapped so that it does
         * not attempt to do a direct access on us.
         */
        info->map.phys = NO_XIP;
        info->map.size = resource_size(dev->resource);

        /*
         * We only support 16-bit accesses for now. If and when
         * any board use 8-bit access, we'll fixup the driver to
         * handle that.
         */
        info->map.bankwidth = 2;
        info->map.name = dev_name(&dev->dev);
        info->map.read = ixp4xx_read16;
        info->map.write = ixp4xx_probe_write16;
        info->map.copy_from = ixp4xx_copy_from;

        info->map.virt = devm_ioremap_resource(&dev->dev, dev->resource);
        if (IS_ERR(info->map.virt)) {
                err = PTR_ERR(info->map.virt);
                goto Error;
        }

        info->mtd = do_map_probe(plat->map_name, &info->map);
        if (!info->mtd) {
                printk(KERN_ERR "IXP4XXFlash: map_probe failed\n");
                err = -ENXIO;
                goto Error;
        }
        info->mtd->dev.parent = &dev->dev;

        /* Use the fast version */
        info->map.write = ixp4xx_write16;

        err = mtd_device_parse_register(info->mtd, probes, &ppdata,
                        plat->parts, plat->nr_parts);
        if (err) {
                printk(KERN_ERR "Could not parse partitions\n");
                goto Error;
        }

        return 0;

Error:
        ixp4xx_flash_remove(dev);
        return err;
}

static struct platform_driver ixp4xx_flash_driver = {
        .probe          = ixp4xx_flash_probe,
        .remove         = ixp4xx_flash_remove,
        .driver         = {
                .name   = "IXP4XX-Flash",
        },
};

module_platform_driver(ixp4xx_flash_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MTD map driver for Intel IXP4xx systems");
MODULE_AUTHOR("Deepak Saxena");
MODULE_ALIAS("platform:IXP4XX-Flash");