root/drivers/mtd/devices/ms02-nv.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Copyright (c) 2001 Maciej W. Rozycki
 */

#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <asm/addrspace.h>
#include <asm/bootinfo.h>
#include <asm/dec/ioasic_addrs.h>
#include <asm/dec/kn02.h>
#include <asm/dec/kn03.h>
#include <asm/io.h>
#include <asm/paccess.h>

#include "ms02-nv.h"


static char version[] __initdata =
        "ms02-nv.c: v.1.0.0  13 Aug 2001  Maciej W. Rozycki.\n";

MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
MODULE_DESCRIPTION("DEC MS02-NV NVRAM module driver");
MODULE_LICENSE("GPL");


/*
 * Addresses we probe for an MS02-NV at.  Modules may be located
 * at any 8MiB boundary within a 0MiB up to 112MiB range or at any 32MiB
 * boundary within a 0MiB up to 448MiB range.  We don't support a module
 * at 0MiB, though.
 */
static ulong ms02nv_addrs[] __initdata = {
        0x07000000, 0x06800000, 0x06000000, 0x05800000, 0x05000000,
        0x04800000, 0x04000000, 0x03800000, 0x03000000, 0x02800000,
        0x02000000, 0x01800000, 0x01000000, 0x00800000
};

static const char ms02nv_name[] = "DEC MS02-NV NVRAM";
static const char ms02nv_res_diag_ram[] = "Diagnostic RAM";
static const char ms02nv_res_user_ram[] = "General-purpose RAM";
static const char ms02nv_res_csr[] = "Control and status register";

static struct mtd_info *root_ms02nv_mtd;


static int ms02nv_read(struct mtd_info *mtd, loff_t from,
                        size_t len, size_t *retlen, u_char *buf)
{
        struct ms02nv_private *mp = mtd->priv;

        memcpy(buf, mp->uaddr + from, len);
        *retlen = len;
        return 0;
}

static int ms02nv_write(struct mtd_info *mtd, loff_t to,
                        size_t len, size_t *retlen, const u_char *buf)
{
        struct ms02nv_private *mp = mtd->priv;

        memcpy(mp->uaddr + to, buf, len);
        *retlen = len;
        return 0;
}


static inline uint ms02nv_probe_one(ulong addr)
{
        ms02nv_uint *ms02nv_diagp;
        ms02nv_uint *ms02nv_magicp;
        uint ms02nv_diag;
        uint ms02nv_magic;
        size_t size;

        int err;

        /*
         * The firmware writes MS02NV_ID at MS02NV_MAGIC and also
         * a diagnostic status at MS02NV_DIAG.
         */
        ms02nv_diagp = (ms02nv_uint *)(CKSEG1ADDR(addr + MS02NV_DIAG));
        ms02nv_magicp = (ms02nv_uint *)(CKSEG1ADDR(addr + MS02NV_MAGIC));
        err = get_dbe(ms02nv_magic, ms02nv_magicp);
        if (err)
                return 0;
        if (ms02nv_magic != MS02NV_ID)
                return 0;

        ms02nv_diag = *ms02nv_diagp;
        size = (ms02nv_diag & MS02NV_DIAG_SIZE_MASK) << MS02NV_DIAG_SIZE_SHIFT;
        if (size > MS02NV_CSR)
                size = MS02NV_CSR;

        return size;
}

static int __init ms02nv_init_one(ulong addr)
{
        struct mtd_info *mtd;
        struct ms02nv_private *mp;
        struct resource *mod_res;
        struct resource *diag_res;
        struct resource *user_res;
        struct resource *csr_res;
        ulong fixaddr;
        size_t size, fixsize;

        static int version_printed;

        int ret = -ENODEV;

        /* The module decodes 8MiB of address space. */
        mod_res = kzalloc_obj(*mod_res);
        if (!mod_res)
                return -ENOMEM;

        mod_res->name = ms02nv_name;
        mod_res->start = addr;
        mod_res->end = addr + MS02NV_SLOT_SIZE - 1;
        mod_res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        if (request_resource(&iomem_resource, mod_res) < 0)
                goto err_out_mod_res;

        size = ms02nv_probe_one(addr);
        if (!size)
                goto err_out_mod_res_rel;

        if (!version_printed) {
                printk(KERN_INFO "%s", version);
                version_printed = 1;
        }

        ret = -ENOMEM;
        mtd = kzalloc_obj(*mtd);
        if (!mtd)
                goto err_out_mod_res_rel;
        mp = kzalloc_obj(*mp);
        if (!mp)
                goto err_out_mtd;

        mtd->priv = mp;
        mp->resource.module = mod_res;

        /* Firmware's diagnostic NVRAM area. */
        diag_res = kzalloc_obj(*diag_res);
        if (!diag_res)
                goto err_out_mp;

        diag_res->name = ms02nv_res_diag_ram;
        diag_res->start = addr;
        diag_res->end = addr + MS02NV_RAM - 1;
        diag_res->flags = IORESOURCE_BUSY;
        request_resource(mod_res, diag_res);

        mp->resource.diag_ram = diag_res;

        /* User-available general-purpose NVRAM area. */
        user_res = kzalloc_obj(*user_res);
        if (!user_res)
                goto err_out_diag_res;

        user_res->name = ms02nv_res_user_ram;
        user_res->start = addr + MS02NV_RAM;
        user_res->end = addr + size - 1;
        user_res->flags = IORESOURCE_BUSY;
        request_resource(mod_res, user_res);

        mp->resource.user_ram = user_res;

        /* Control and status register. */
        csr_res = kzalloc_obj(*csr_res);
        if (!csr_res)
                goto err_out_user_res;

        csr_res->name = ms02nv_res_csr;
        csr_res->start = addr + MS02NV_CSR;
        csr_res->end = addr + MS02NV_CSR + 3;
        csr_res->flags = IORESOURCE_BUSY;
        request_resource(mod_res, csr_res);

        mp->resource.csr = csr_res;

        mp->addr = phys_to_virt(addr);
        mp->size = size;

        /*
         * Hide the firmware's diagnostic area.  It may get destroyed
         * upon a reboot.  Take paging into account for mapping support.
         */
        fixaddr = (addr + MS02NV_RAM + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
        fixsize = (size - (fixaddr - addr)) & ~(PAGE_SIZE - 1);
        mp->uaddr = phys_to_virt(fixaddr);

        mtd->type = MTD_RAM;
        mtd->flags = MTD_CAP_RAM;
        mtd->size = fixsize;
        mtd->name = ms02nv_name;
        mtd->owner = THIS_MODULE;
        mtd->_read = ms02nv_read;
        mtd->_write = ms02nv_write;
        mtd->writesize = 1;

        ret = -EIO;
        if (mtd_device_register(mtd, NULL, 0)) {
                printk(KERN_ERR
                        "ms02-nv: Unable to register MTD device, aborting!\n");
                goto err_out_csr_res;
        }

        printk(KERN_INFO "mtd%d: %s at 0x%08lx, size %zuMiB.\n",
                mtd->index, ms02nv_name, addr, size >> 20);

        mp->next = root_ms02nv_mtd;
        root_ms02nv_mtd = mtd;

        return 0;


err_out_csr_res:
        release_resource(csr_res);
        kfree(csr_res);
err_out_user_res:
        release_resource(user_res);
        kfree(user_res);
err_out_diag_res:
        release_resource(diag_res);
        kfree(diag_res);
err_out_mp:
        kfree(mp);
err_out_mtd:
        kfree(mtd);
err_out_mod_res_rel:
        release_resource(mod_res);
err_out_mod_res:
        kfree(mod_res);
        return ret;
}

static void __exit ms02nv_remove_one(void)
{
        struct mtd_info *mtd = root_ms02nv_mtd;
        struct ms02nv_private *mp = mtd->priv;

        root_ms02nv_mtd = mp->next;

        mtd_device_unregister(mtd);

        release_resource(mp->resource.csr);
        kfree(mp->resource.csr);
        release_resource(mp->resource.user_ram);
        kfree(mp->resource.user_ram);
        release_resource(mp->resource.diag_ram);
        kfree(mp->resource.diag_ram);
        release_resource(mp->resource.module);
        kfree(mp->resource.module);
        kfree(mp);
        kfree(mtd);
}


static int __init ms02nv_init(void)
{
        volatile u32 *csr;
        uint stride = 0;
        int count = 0;
        int i;

        switch (mips_machtype) {
        case MACH_DS5000_200:
                csr = (volatile u32 *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CSR);
                if (*csr & KN02_CSR_BNK32M)
                        stride = 2;
                break;
        case MACH_DS5000_2X0:
        case MACH_DS5900:
                csr = (volatile u32 *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_MCR);
                if (*csr & KN03_MCR_BNK32M)
                        stride = 2;
                break;
        default:
                return -ENODEV;
        }

        for (i = 0; i < ARRAY_SIZE(ms02nv_addrs); i++)
                if (!ms02nv_init_one(ms02nv_addrs[i] << stride))
                        count++;

        return (count > 0) ? 0 : -ENODEV;
}

static void __exit ms02nv_cleanup(void)
{
        while (root_ms02nv_mtd)
                ms02nv_remove_one();
}


module_init(ms02nv_init);
module_exit(ms02nv_cleanup);