// SPDX-License-Identifier: GPL-2.0-only
/*
 * amd76xrom.c
 *
 * Normal mappings of chips in physical memory
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/cfi.h>
#include <linux/mtd/flashchip.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#include <linux/list.h>


#define xstr(s) str(s)
#define str(s) #s
#define MOD_NAME xstr(KBUILD_BASENAME)

#define ADDRESS_NAME_LEN 18

#define ROM_PROBE_STEP_SIZE (64*1024) /* 64KiB */

struct amd76xrom_window {
        void __iomem *virt;
        unsigned long phys;
        unsigned long size;
        struct list_head maps;
        struct resource rsrc;
        struct pci_dev *pdev;
};

struct amd76xrom_map_info {
        struct list_head list;
        struct map_info map;
        struct mtd_info *mtd;
        struct resource rsrc;
        char map_name[sizeof(MOD_NAME) + 2 + ADDRESS_NAME_LEN];
};

/* The 2 bits controlling the window size are often set to allow reading
 * the BIOS, but too small to allow writing, since the lock registers are
 * 4MiB lower in the address space than the data.
 *
 * This is intended to prevent flashing the bios, perhaps accidentally.
 *
 * This parameter allows the normal driver to over-ride the BIOS settings.
 *
 * The bits are 6 and 7.  If both bits are set, it is a 5MiB window.
 * If only the 7 Bit is set, it is a 4MiB window.  Otherwise, a
 * 64KiB window.
 *
 */
static uint win_size_bits;
module_param(win_size_bits, uint, 0);
MODULE_PARM_DESC(win_size_bits, "ROM window size bits override for 0x43 byte, normally set by BIOS.");

static struct amd76xrom_window amd76xrom_window = {
        .maps = LIST_HEAD_INIT(amd76xrom_window.maps),
};

static void amd76xrom_cleanup(struct amd76xrom_window *window)
{
        struct amd76xrom_map_info *map, *scratch;
        u8 byte;

        if (window->pdev) {
                /* Disable writes through the rom window */
                pci_read_config_byte(window->pdev, 0x40, &byte);
                pci_write_config_byte(window->pdev, 0x40, byte & ~1);
                pci_dev_put(window->pdev);
        }

        /* Free all of the mtd devices */
        list_for_each_entry_safe(map, scratch, &window->maps, list) {
                if (map->rsrc.parent) {
                        release_resource(&map->rsrc);
                }
                mtd_device_unregister(map->mtd);
                map_destroy(map->mtd);
                list_del(&map->list);
                kfree(map);
        }
        if (window->rsrc.parent)
                release_resource(&window->rsrc);

        if (window->virt) {
                iounmap(window->virt);
                window->virt = NULL;
                window->phys = 0;
                window->size = 0;
                window->pdev = NULL;
        }
}


static int amd76xrom_init_one(struct pci_dev *pdev,
                              const struct pci_device_id *ent)
{
        static char *rom_probe_types[] = { "cfi_probe", "jedec_probe", NULL };
        u8 byte;
        struct amd76xrom_window *window = &amd76xrom_window;
        struct amd76xrom_map_info *map = NULL;
        unsigned long map_top;

        /* Remember the pci dev I find the window in - already have a ref */
        window->pdev = pdev;

        /* Enable the selected rom window.  This is often incorrectly
         * set up by the BIOS, and the 4MiB offset for the lock registers
         * requires the full 5MiB of window space.
         *
         * This 'write, then read' approach leaves the bits for
         * other uses of the hardware info.
         */
        pci_read_config_byte(pdev, 0x43, &byte);
        pci_write_config_byte(pdev, 0x43, byte | win_size_bits );

        /* Assume the rom window is properly setup, and find it's size */
        pci_read_config_byte(pdev, 0x43, &byte);
        if ((byte & ((1<<7)|(1<<6))) == ((1<<7)|(1<<6))) {
                window->phys = 0xffb00000; /* 5MiB */
        }
        else if ((byte & (1<<7)) == (1<<7)) {
                window->phys = 0xffc00000; /* 4MiB */
        }
        else {
                window->phys = 0xffff0000; /* 64KiB */
        }
        window->size = 0xffffffffUL - window->phys + 1UL;

        /*
         * Try to reserve the window mem region.  If this fails then
         * it is likely due to a fragment of the window being
         * "reserved" by the BIOS.  In the case that the
         * request_mem_region() fails then once the rom size is
         * discovered we will try to reserve the unreserved fragment.
         */
        window->rsrc.name = MOD_NAME;
        window->rsrc.start = window->phys;
        window->rsrc.end   = window->phys + window->size - 1;
        window->rsrc.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        if (request_resource(&iomem_resource, &window->rsrc)) {
                window->rsrc.parent = NULL;
                printk(KERN_ERR MOD_NAME
                       " %s(): Unable to register resource %pR - kernel bug?\n",
                       __func__, &window->rsrc);
                return -EBUSY;
        }


        /* Enable writes through the rom window */
        pci_read_config_byte(pdev, 0x40, &byte);
        pci_write_config_byte(pdev, 0x40, byte | 1);

        /* FIXME handle registers 0x80 - 0x8C the bios region locks */

        /* For write accesses caches are useless */
        window->virt = ioremap_nocache(window->phys, window->size);
        if (!window->virt) {
                printk(KERN_ERR MOD_NAME ": ioremap(%08lx, %08lx) failed\n",
                        window->phys, window->size);
                goto out;
        }

        /* Get the first address to look for an rom chip at */
        map_top = window->phys;
#if 1
        /* The probe sequence run over the firmware hub lock
         * registers sets them to 0x7 (no access).
         * Probe at most the last 4M of the address space.
         */
        if (map_top < 0xffc00000) {
                map_top = 0xffc00000;
        }
#endif
        /* Loop  through and look for rom chips */
        while((map_top - 1) < 0xffffffffUL) {
                struct cfi_private *cfi;
                unsigned long offset;
                int i;

                if (!map) {
                        map = kmalloc(sizeof(*map), GFP_KERNEL);
                }
                if (!map) {
                        printk(KERN_ERR MOD_NAME ": kmalloc failed");
                        goto out;
                }
                memset(map, 0, sizeof(*map));
                INIT_LIST_HEAD(&map->list);
                map->map.name = map->map_name;
                map->map.phys = map_top;
                offset = map_top - window->phys;
                map->map.virt = (void __iomem *)
                        (((unsigned long)(window->virt)) + offset);
                map->map.size = 0xffffffffUL - map_top + 1UL;
                /* Set the name of the map to the address I am trying */
                sprintf(map->map_name, "%s @%08Lx",
                        MOD_NAME, (unsigned long long)map->map.phys);

                /* There is no generic VPP support */
                for(map->map.bankwidth = 32; map->map.bankwidth;
                        map->map.bankwidth >>= 1)
                {
                        char **probe_type;
                        /* Skip bankwidths that are not supported */
                        if (!map_bankwidth_supported(map->map.bankwidth))
                                continue;

                        /* Setup the map methods */
                        simple_map_init(&map->map);

                        /* Try all of the probe methods */
                        probe_type = rom_probe_types;
                        for(; *probe_type; probe_type++) {
                                map->mtd = do_map_probe(*probe_type, &map->map);
                                if (map->mtd)
                                        goto found;
                        }
                }
                map_top += ROM_PROBE_STEP_SIZE;
                continue;
        found:
                /* Trim the size if we are larger than the map */
                if (map->mtd->size > map->map.size) {
                        printk(KERN_WARNING MOD_NAME
                                " rom(%llu) larger than window(%lu). fixing...\n",
                                (unsigned long long)map->mtd->size, map->map.size);
                        map->mtd->size = map->map.size;
                }
                if (window->rsrc.parent) {
                        /*
                         * Registering the MTD device in iomem may not be possible
                         * if there is a BIOS "reserved" and BUSY range.  If this
                         * fails then continue anyway.
                         */
                        map->rsrc.name  = map->map_name;
                        map->rsrc.start = map->map.phys;
                        map->rsrc.end   = map->map.phys + map->mtd->size - 1;
                        map->rsrc.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
                        if (request_resource(&window->rsrc, &map->rsrc)) {
                                printk(KERN_ERR MOD_NAME
                                        ": cannot reserve MTD resource\n");
                                map->rsrc.parent = NULL;
                        }
                }

                /* Make the whole region visible in the map */
                map->map.virt = window->virt;
                map->map.phys = window->phys;
                cfi = map->map.fldrv_priv;
                for(i = 0; i < cfi->numchips; i++) {
                        cfi->chips[i].start += offset;
                }

                /* Now that the mtd devices is complete claim and export it */
                map->mtd->owner = THIS_MODULE;
                if (mtd_device_register(map->mtd, NULL, 0)) {
                        map_destroy(map->mtd);
                        map->mtd = NULL;
                        goto out;
                }


                /* Calculate the new value of map_top */
                map_top += map->mtd->size;

                /* File away the map structure */
                list_add(&map->list, &window->maps);
                map = NULL;
        }

 out:
        /* Free any left over map structures */
        kfree(map);
        /* See if I have any map structures */
        if (list_empty(&window->maps)) {
                amd76xrom_cleanup(window);
                return -ENODEV;
        }
        return 0;
}


static void amd76xrom_remove_one(struct pci_dev *pdev)
{
        struct amd76xrom_window *window = &amd76xrom_window;

        amd76xrom_cleanup(window);
}

static const struct pci_device_id amd76xrom_pci_tbl[] = {
        { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_VIPER_7410,
                PCI_ANY_ID, PCI_ANY_ID, },
        { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_VIPER_7440,
                PCI_ANY_ID, PCI_ANY_ID, },
        { PCI_VENDOR_ID_AMD, 0x7468 }, /* amd8111 support */
        { 0, }
};

MODULE_DEVICE_TABLE(pci, amd76xrom_pci_tbl);

#if 0
static struct pci_driver amd76xrom_driver = {
        .name =         MOD_NAME,
        .id_table =     amd76xrom_pci_tbl,
        .probe =        amd76xrom_init_one,
        .remove =       amd76xrom_remove_one,
};
#endif

static int __init init_amd76xrom(void)
{
        struct pci_dev *pdev;
        const struct pci_device_id *id;
        pdev = NULL;
        for(id = amd76xrom_pci_tbl; id->vendor; id++) {
                pdev = pci_get_device(id->vendor, id->device, NULL);
                if (pdev) {
                        break;
                }
        }
        if (pdev) {
                return amd76xrom_init_one(pdev, &amd76xrom_pci_tbl[0]);
        }
        return -ENXIO;
#if 0
        return pci_register_driver(&amd76xrom_driver);
#endif
}

static void __exit cleanup_amd76xrom(void)
{
        amd76xrom_remove_one(amd76xrom_window.pdev);
}

module_init(init_amd76xrom);
module_exit(cleanup_amd76xrom);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Eric Biederman <ebiederman@lnxi.com>");
MODULE_DESCRIPTION("MTD map driver for BIOS chips on the AMD76X southbridge");