// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 *  Copyright (C) 2004 Liu Peng Infineon IFAP DC COM CPE
 *  Copyright (C) 2010 John Crispin <john@phrozen.org>
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/cfi.h>
#include <linux/platform_device.h>
#include <linux/mtd/physmap.h>
#include <linux/of.h>

#include <lantiq_soc.h>

/*
 * The NOR flash is connected to the same external bus unit (EBU) as PCI.
 * To make PCI work we need to enable the endianness swapping for the address
 * written to the EBU. This endianness swapping works for PCI correctly but
 * fails for attached NOR devices. To workaround this we need to use a complex
 * map. The workaround involves swapping all addresses whilst probing the chip.
 * Once probing is complete we stop swapping the addresses but swizzle the
 * unlock addresses to ensure that access to the NOR device works correctly.
 */

enum {
        LTQ_NOR_PROBING,
        LTQ_NOR_NORMAL
};

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

static const char ltq_map_name[] = "ltq_nor";

static map_word
ltq_read16(struct map_info *map, unsigned long adr)
{
        unsigned long flags;
        map_word temp;

        if (map->map_priv_1 == LTQ_NOR_PROBING)
                adr ^= 2;
        spin_lock_irqsave(&ebu_lock, flags);
        temp.x[0] = *(u16 *)(map->virt + adr);
        spin_unlock_irqrestore(&ebu_lock, flags);
        return temp;
}

static void
ltq_write16(struct map_info *map, map_word d, unsigned long adr)
{
        unsigned long flags;

        if (map->map_priv_1 == LTQ_NOR_PROBING)
                adr ^= 2;
        spin_lock_irqsave(&ebu_lock, flags);
        *(u16 *)(map->virt + adr) = d.x[0];
        spin_unlock_irqrestore(&ebu_lock, flags);
}

/*
 * The following 2 functions copy data between iomem and a cached memory
 * section. As memcpy() makes use of pre-fetching we cannot use it here.
 * The normal alternative of using memcpy_{to,from}io also makes use of
 * memcpy() on MIPS so it is not applicable either. We are therefore stuck
 * with having to use our own loop.
 */
static void
ltq_copy_from(struct map_info *map, void *to,
        unsigned long from, ssize_t len)
{
        unsigned char *f = (unsigned char *)map->virt + from;
        unsigned char *t = (unsigned char *)to;
        unsigned long flags;

        spin_lock_irqsave(&ebu_lock, flags);
        while (len--)
                *t++ = *f++;
        spin_unlock_irqrestore(&ebu_lock, flags);
}

static void
ltq_copy_to(struct map_info *map, unsigned long to,
        const void *from, ssize_t len)
{
        unsigned char *f = (unsigned char *)from;
        unsigned char *t = (unsigned char *)map->virt + to;
        unsigned long flags;

        spin_lock_irqsave(&ebu_lock, flags);
        while (len--)
                *t++ = *f++;
        spin_unlock_irqrestore(&ebu_lock, flags);
}

static int
ltq_mtd_probe(struct platform_device *pdev)
{
        struct ltq_mtd *ltq_mtd;
        struct cfi_private *cfi;
        int err;

        ltq_mtd = devm_kzalloc(&pdev->dev, sizeof(struct ltq_mtd), GFP_KERNEL);
        if (!ltq_mtd)
                return -ENOMEM;

        platform_set_drvdata(pdev, ltq_mtd);

        ltq_mtd->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!ltq_mtd->res) {
                dev_err(&pdev->dev, "failed to get memory resource\n");
                return -ENOENT;
        }

        ltq_mtd->map = devm_kzalloc(&pdev->dev, sizeof(struct map_info),
                                    GFP_KERNEL);
        if (!ltq_mtd->map)
                return -ENOMEM;

        ltq_mtd->map->phys = ltq_mtd->res->start;
        ltq_mtd->map->size = resource_size(ltq_mtd->res);
        ltq_mtd->map->virt = devm_ioremap_resource(&pdev->dev, ltq_mtd->res);
        if (IS_ERR(ltq_mtd->map->virt))
                return PTR_ERR(ltq_mtd->map->virt);

        ltq_mtd->map->name = ltq_map_name;
        ltq_mtd->map->bankwidth = 2;
        ltq_mtd->map->read = ltq_read16;
        ltq_mtd->map->write = ltq_write16;
        ltq_mtd->map->copy_from = ltq_copy_from;
        ltq_mtd->map->copy_to = ltq_copy_to;

        ltq_mtd->map->map_priv_1 = LTQ_NOR_PROBING;
        ltq_mtd->mtd = do_map_probe("cfi_probe", ltq_mtd->map);
        ltq_mtd->map->map_priv_1 = LTQ_NOR_NORMAL;

        if (!ltq_mtd->mtd) {
                dev_err(&pdev->dev, "probing failed\n");
                return -ENXIO;
        }

        ltq_mtd->mtd->dev.parent = &pdev->dev;
        mtd_set_of_node(ltq_mtd->mtd, pdev->dev.of_node);

        cfi = ltq_mtd->map->fldrv_priv;
        cfi->addr_unlock1 ^= 1;
        cfi->addr_unlock2 ^= 1;

        err = mtd_device_register(ltq_mtd->mtd, NULL, 0);
        if (err) {
                dev_err(&pdev->dev, "failed to add partitions\n");
                goto err_destroy;
        }

        return 0;

err_destroy:
        map_destroy(ltq_mtd->mtd);
        return err;
}

static int
ltq_mtd_remove(struct platform_device *pdev)
{
        struct ltq_mtd *ltq_mtd = platform_get_drvdata(pdev);

        if (ltq_mtd && ltq_mtd->mtd) {
                mtd_device_unregister(ltq_mtd->mtd);
                map_destroy(ltq_mtd->mtd);
        }
        return 0;
}

static const struct of_device_id ltq_mtd_match[] = {
        { .compatible = "lantiq,nor" },
        {},
};
MODULE_DEVICE_TABLE(of, ltq_mtd_match);

static struct platform_driver ltq_mtd_driver = {
        .probe = ltq_mtd_probe,
        .remove = ltq_mtd_remove,
        .driver = {
                .name = "ltq-nor",
                .of_match_table = ltq_mtd_match,
        },
};

module_platform_driver(ltq_mtd_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Crispin <john@phrozen.org>");
MODULE_DESCRIPTION("Lantiq SoC NOR");