// SPDX-License-Identifier: GPL-2.0
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/ioport.h>
#include <linux/seq_file.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/edd.h>
#include <linux/dmi.h>
#include <linux/pfn.h>
#include <linux/pci.h>
#include <linux/export.h>

#include <asm/probe_roms.h>
#include <asm/pci-direct.h>
#include <asm/e820/api.h>
#include <asm/mmzone.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/io.h>
#include <asm/setup_arch.h>
#include <asm/sev.h>

static struct resource system_rom_resource = {
        .name   = "System ROM",
        .start  = 0xf0000,
        .end    = 0xfffff,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource extension_rom_resource = {
        .name   = "Extension ROM",
        .start  = 0xe0000,
        .end    = 0xeffff,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource adapter_rom_resources[] = { {
        .name   = "Adapter ROM",
        .start  = 0xc8000,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
        .name   = "Adapter ROM",
        .start  = 0,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
        .name   = "Adapter ROM",
        .start  = 0,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
        .name   = "Adapter ROM",
        .start  = 0,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
        .name   = "Adapter ROM",
        .start  = 0,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
        .name   = "Adapter ROM",
        .start  = 0,
        .end    = 0,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
} };

static struct resource video_rom_resource = {
        .name   = "Video ROM",
        .start  = 0xc0000,
        .end    = 0xc7fff,
        .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

/* does this oprom support the given pci device, or any of the devices
 * that the driver supports?
 */
static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
{
        struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
        const struct pci_device_id *id;

        if (pdev->vendor == vendor && pdev->device == device)
                return true;

        for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
                if (id->vendor == vendor && id->device == device)
                        break;

        return id && id->vendor;
}

static bool probe_list(struct pci_dev *pdev, unsigned short vendor,
                       const void *rom_list)
{
        unsigned short device;

        do {
                if (get_kernel_nofault(device, rom_list) != 0)
                        device = 0;

                if (device && match_id(pdev, vendor, device))
                        break;

                rom_list += 2;
        } while (device);

        return !!device;
}

static struct resource *find_oprom(struct pci_dev *pdev)
{
        struct resource *oprom = NULL;
        int i;

        for (i = 0; i < ARRAY_SIZE(adapter_rom_resources); i++) {
                struct resource *res = &adapter_rom_resources[i];
                unsigned short offset, vendor, device, list, rev;
                const void *rom;

                if (res->end == 0)
                        break;

                rom = isa_bus_to_virt(res->start);
                if (get_kernel_nofault(offset, rom + 0x18) != 0)
                        continue;

                if (get_kernel_nofault(vendor, rom + offset + 0x4) != 0)
                        continue;

                if (get_kernel_nofault(device, rom + offset + 0x6) != 0)
                        continue;

                if (match_id(pdev, vendor, device)) {
                        oprom = res;
                        break;
                }

                if (get_kernel_nofault(list, rom + offset + 0x8) == 0 &&
                    get_kernel_nofault(rev, rom + offset + 0xc) == 0 &&
                    rev >= 3 && list &&
                    probe_list(pdev, vendor, rom + offset + list)) {
                        oprom = res;
                        break;
                }
        }

        return oprom;
}

void __iomem *pci_map_biosrom(struct pci_dev *pdev)
{
        struct resource *oprom = find_oprom(pdev);

        if (!oprom)
                return NULL;

        return ioremap(oprom->start, resource_size(oprom));
}
EXPORT_SYMBOL(pci_map_biosrom);

void pci_unmap_biosrom(void __iomem *image)
{
        iounmap(image);
}
EXPORT_SYMBOL(pci_unmap_biosrom);

size_t pci_biosrom_size(struct pci_dev *pdev)
{
        struct resource *oprom = find_oprom(pdev);

        return oprom ? resource_size(oprom) : 0;
}
EXPORT_SYMBOL(pci_biosrom_size);

#define ROMSIGNATURE 0xaa55

static int __init romsignature(const unsigned char *rom)
{
        const unsigned short * const ptr = (const unsigned short *)rom;
        unsigned short sig;

        return get_kernel_nofault(sig, ptr) == 0 && sig == ROMSIGNATURE;
}

static int __init romchecksum(const unsigned char *rom, unsigned long length)
{
        unsigned char sum, c;

        for (sum = 0; length && get_kernel_nofault(c, rom++) == 0; length--)
                sum += c;
        return !length && !sum;
}

void __init probe_roms(void)
{
        unsigned long start, length, upper;
        const unsigned char *rom;
        unsigned char c;
        int i;

        /* video rom */
        upper = adapter_rom_resources[0].start;
        for (start = video_rom_resource.start; start < upper; start += 2048) {
                rom = isa_bus_to_virt(start);
                if (!romsignature(rom))
                        continue;

                video_rom_resource.start = start;

                if (get_kernel_nofault(c, rom + 2) != 0)
                        continue;

                /* 0 < length <= 0x7f * 512, historically */
                length = c * 512;

                /* if checksum okay, trust length byte */
                if (length && romchecksum(rom, length))
                        video_rom_resource.end = start + length - 1;

                request_resource(&iomem_resource, &video_rom_resource);
                break;
        }

        start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
        if (start < upper)
                start = upper;

        /* system rom */
        request_resource(&iomem_resource, &system_rom_resource);
        upper = system_rom_resource.start;

        /* check for extension rom (ignore length byte!) */
        rom = isa_bus_to_virt(extension_rom_resource.start);
        if (romsignature(rom)) {
                length = resource_size(&extension_rom_resource);
                if (romchecksum(rom, length)) {
                        request_resource(&iomem_resource, &extension_rom_resource);
                        upper = extension_rom_resource.start;
                }
        }

        /* check for adapter roms on 2k boundaries */
        for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
                rom = isa_bus_to_virt(start);
                if (!romsignature(rom))
                        continue;

                if (get_kernel_nofault(c, rom + 2) != 0)
                        continue;

                /* 0 < length <= 0x7f * 512, historically */
                length = c * 512;

                /* but accept any length that fits if checksum okay */
                if (!length || start + length > upper || !romchecksum(rom, length))
                        continue;

                adapter_rom_resources[i].start = start;
                adapter_rom_resources[i].end = start + length - 1;
                request_resource(&iomem_resource, &adapter_rom_resources[i]);

                start = adapter_rom_resources[i++].end & ~2047UL;
        }
}