// SPDX-License-Identifier: GPL-2.0
/*
 * Firmware replacement code.
 *
 * Work around broken BIOSes that don't set an aperture, only set the
 * aperture in the AGP bridge, or set too small aperture.
 *
 * If all fails map the aperture over some low memory.  This is cheaper than
 * doing bounce buffering. The memory is lost. This is done at early boot
 * because only the bootmem allocator can allocate 32+MB.
 *
 * Copyright 2002 Andi Kleen, SuSE Labs.
 */
#define pr_fmt(fmt) "AGP: " fmt

#include <linux/kernel.h>
#include <linux/kcore.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/mmzone.h>
#include <linux/pci_ids.h>
#include <linux/pci.h>
#include <linux/bitops.h>
#include <linux/suspend.h>
#include <asm/e820/api.h>
#include <asm/io.h>
#include <asm/iommu.h>
#include <asm/gart.h>
#include <asm/pci-direct.h>
#include <asm/dma.h>
#include <asm/amd_nb.h>
#include <asm/x86_init.h>
#include <linux/crash_dump.h>

/*
 * Using 512M as goal, in case kexec will load kernel_big
 * that will do the on-position decompress, and could overlap with
 * with the gart aperture that is used.
 * Sequence:
 * kernel_small
 * ==> kexec (with kdump trigger path or gart still enabled)
 * ==> kernel_small (gart area become e820_reserved)
 * ==> kexec (with kdump trigger path or gart still enabled)
 * ==> kerne_big (uncompressed size will be big than 64M or 128M)
 * So don't use 512M below as gart iommu, leave the space for kernel
 * code for safe.
 */
#define GART_MIN_ADDR   (512ULL << 20)
#define GART_MAX_ADDR   (1ULL   << 32)

int gart_iommu_aperture;
int gart_iommu_aperture_disabled __initdata;
int gart_iommu_aperture_allowed __initdata;

int fallback_aper_order __initdata = 1; /* 64MB */
int fallback_aper_force __initdata;

int fix_aperture __initdata = 1;

#if defined(CONFIG_PROC_VMCORE) || defined(CONFIG_PROC_KCORE)
/*
 * If the first kernel maps the aperture over e820 RAM, the kdump kernel will
 * use the same range because it will remain configured in the northbridge.
 * Trying to dump this area via /proc/vmcore may crash the machine, so exclude
 * it from vmcore.
 */
static unsigned long aperture_pfn_start, aperture_page_count;

static int gart_mem_pfn_is_ram(unsigned long pfn)
{
        return likely((pfn < aperture_pfn_start) ||
                      (pfn >= aperture_pfn_start + aperture_page_count));
}

static void __init exclude_from_core(u64 aper_base, u32 aper_order)
{
        aperture_pfn_start = aper_base >> PAGE_SHIFT;
        aperture_page_count = (32 * 1024 * 1024) << aper_order >> PAGE_SHIFT;
#ifdef CONFIG_PROC_VMCORE
        WARN_ON(register_oldmem_pfn_is_ram(&gart_mem_pfn_is_ram));
#endif
#ifdef CONFIG_PROC_KCORE
        WARN_ON(register_mem_pfn_is_ram(&gart_mem_pfn_is_ram));
#endif
}
#else
static void exclude_from_core(u64 aper_base, u32 aper_order)
{
}
#endif

/* This code runs before the PCI subsystem is initialized, so just
   access the northbridge directly. */

static u32 __init allocate_aperture(void)
{
        u32 aper_size;
        unsigned long addr;

        /* aper_size should <= 1G */
        if (fallback_aper_order > 5)
                fallback_aper_order = 5;
        aper_size = (32 * 1024 * 1024) << fallback_aper_order;

        /*
         * Aperture has to be naturally aligned. This means a 2GB aperture
         * won't have much chance of finding a place in the lower 4GB of
         * memory. Unfortunately we cannot move it up because that would
         * make the IOMMU useless.
         */
        addr = memblock_phys_alloc_range(aper_size, aper_size,
                                         GART_MIN_ADDR, GART_MAX_ADDR);
        if (!addr) {
                pr_err("Cannot allocate aperture memory hole [mem %#010lx-%#010lx] (%uKB)\n",
                       addr, addr + aper_size - 1, aper_size >> 10);
                return 0;
        }
        pr_info("Mapping aperture over RAM [mem %#010lx-%#010lx] (%uKB)\n",
                addr, addr + aper_size - 1, aper_size >> 10);
        register_nosave_region(addr >> PAGE_SHIFT,
                               (addr+aper_size) >> PAGE_SHIFT);

        return (u32)addr;
}


/* Find a PCI capability */
static u32 __init find_cap(int bus, int slot, int func, int cap)
{
        int bytes;
        u8 pos;

        if (!(read_pci_config_16(bus, slot, func, PCI_STATUS) &
                                                PCI_STATUS_CAP_LIST))
                return 0;

        pos = read_pci_config_byte(bus, slot, func, PCI_CAPABILITY_LIST);
        for (bytes = 0; bytes < 48 && pos >= 0x40; bytes++) {
                u8 id;

                pos &= ~3;
                id = read_pci_config_byte(bus, slot, func, pos+PCI_CAP_LIST_ID);
                if (id == 0xff)
                        break;
                if (id == cap)
                        return pos;
                pos = read_pci_config_byte(bus, slot, func,
                                                pos+PCI_CAP_LIST_NEXT);
        }
        return 0;
}

/* Read a standard AGPv3 bridge header */
static u32 __init read_agp(int bus, int slot, int func, int cap, u32 *order)
{
        u32 apsize;
        u32 apsizereg;
        int nbits;
        u32 aper_low, aper_hi;
        u64 aper;
        u32 old_order;

        pr_info("pci 0000:%02x:%02x:%02x: AGP bridge\n", bus, slot, func);
        apsizereg = read_pci_config_16(bus, slot, func, cap + 0x14);
        if (apsizereg == 0xffffffff) {
                pr_err("pci 0000:%02x:%02x.%d: APSIZE unreadable\n",
                       bus, slot, func);
                return 0;
        }

        /* old_order could be the value from NB gart setting */
        old_order = *order;

        apsize = apsizereg & 0xfff;
        /* Some BIOS use weird encodings not in the AGPv3 table. */
        if (apsize & 0xff)
                apsize |= 0xf00;
        nbits = hweight16(apsize);
        *order = 7 - nbits;
        if ((int)*order < 0) /* < 32MB */
                *order = 0;

        aper_low = read_pci_config(bus, slot, func, 0x10);
        aper_hi = read_pci_config(bus, slot, func, 0x14);
        aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32);

        /*
         * On some sick chips, APSIZE is 0. It means it wants 4G
         * so let double check that order, and lets trust AMD NB settings:
         */
        pr_info("pci 0000:%02x:%02x.%d: AGP aperture [bus addr %#010Lx-%#010Lx] (old size %uMB)\n",
                bus, slot, func, aper, aper + (32ULL << (old_order + 20)) - 1,
                32 << old_order);
        if (aper + (32ULL<<(20 + *order)) > 0x100000000ULL) {
                pr_info("pci 0000:%02x:%02x.%d: AGP aperture size %uMB (APSIZE %#x) is not right, using settings from NB\n",
                        bus, slot, func, 32 << *order, apsizereg);
                *order = old_order;
        }

        pr_info("pci 0000:%02x:%02x.%d: AGP aperture [bus addr %#010Lx-%#010Lx] (%uMB, APSIZE %#x)\n",
                bus, slot, func, aper, aper + (32ULL << (*order + 20)) - 1,
                32 << *order, apsizereg);

        if (!aperture_valid(aper, (32*1024*1024) << *order, 32<<20))
                return 0;
        return (u32)aper;
}

/*
 * Look for an AGP bridge. Windows only expects the aperture in the
 * AGP bridge and some BIOS forget to initialize the Northbridge too.
 * Work around this here.
 *
 * Do an PCI bus scan by hand because we're running before the PCI
 * subsystem.
 *
 * All AMD AGP bridges are AGPv3 compliant, so we can do this scan
 * generically. It's probably overkill to always scan all slots because
 * the AGP bridges should be always an own bus on the HT hierarchy,
 * but do it here for future safety.
 */
static u32 __init search_agp_bridge(u32 *order, int *valid_agp)
{
        int bus, slot, func;

        /* Poor man's PCI discovery */
        for (bus = 0; bus < 256; bus++) {
                for (slot = 0; slot < 32; slot++) {
                        for (func = 0; func < 8; func++) {
                                u32 class, cap;
                                u8 type;
                                class = read_pci_config(bus, slot, func,
                                                        PCI_CLASS_REVISION);
                                if (class == 0xffffffff)
                                        break;

                                switch (class >> 16) {
                                case PCI_CLASS_BRIDGE_HOST:
                                case PCI_CLASS_BRIDGE_OTHER: /* needed? */
                                        /* AGP bridge? */
                                        cap = find_cap(bus, slot, func,
                                                        PCI_CAP_ID_AGP);
                                        if (!cap)
                                                break;
                                        *valid_agp = 1;
                                        return read_agp(bus, slot, func, cap,
                                                        order);
                                }

                                /* No multi-function device? */
                                type = read_pci_config_byte(bus, slot, func,
                                                               PCI_HEADER_TYPE);
                                if (!(type & 0x80))
                                        break;
                        }
                }
        }
        pr_info("No AGP bridge found\n");

        return 0;
}

static bool gart_fix_e820 __initdata = true;

static int __init parse_gart_mem(char *p)
{
        return kstrtobool(p, &gart_fix_e820);
}
early_param("gart_fix_e820", parse_gart_mem);

/*
 * With kexec/kdump, if the first kernel doesn't shut down the GART and the
 * second kernel allocates a different GART region, there might be two
 * overlapping GART regions present:
 *
 * - the first still used by the GART initialized in the first kernel.
 * - (sub-)set of it used as normal RAM by the second kernel.
 *
 * which leads to memory corruptions and a kernel panic eventually.
 *
 * This can also happen if the BIOS has forgotten to mark the GART region
 * as reserved.
 *
 * Try to update the e820 map to mark that new region as reserved.
 */
void __init early_gart_iommu_check(void)
{
        u32 agp_aper_order = 0;
        int i, fix, slot, valid_agp = 0;
        u32 ctl;
        u32 aper_size = 0, aper_order = 0, last_aper_order = 0;
        u64 aper_base = 0, last_aper_base = 0;
        int aper_enabled = 0, last_aper_enabled = 0, last_valid = 0;

        if (!amd_gart_present())
                return;

        if (!early_pci_allowed())
                return;

        /* This is mostly duplicate of iommu_hole_init */
        search_agp_bridge(&agp_aper_order, &valid_agp);

        fix = 0;
        for (i = 0; amd_nb_bus_dev_ranges[i].dev_limit; i++) {
                int bus;
                int dev_base, dev_limit;

                bus = amd_nb_bus_dev_ranges[i].bus;
                dev_base = amd_nb_bus_dev_ranges[i].dev_base;
                dev_limit = amd_nb_bus_dev_ranges[i].dev_limit;

                for (slot = dev_base; slot < dev_limit; slot++) {
                        if (!early_is_amd_nb(read_pci_config(bus, slot, 3, 0x00)))
                                continue;

                        ctl = read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL);
                        aper_enabled = ctl & GARTEN;
                        aper_order = (ctl >> 1) & 7;
                        aper_size = (32 * 1024 * 1024) << aper_order;
                        aper_base = read_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE) & 0x7fff;
                        aper_base <<= 25;

                        if (last_valid) {
                                if ((aper_order != last_aper_order) ||
                                    (aper_base != last_aper_base) ||
                                    (aper_enabled != last_aper_enabled)) {
                                        fix = 1;
                                        break;
                                }
                        }

                        last_aper_order = aper_order;
                        last_aper_base = aper_base;
                        last_aper_enabled = aper_enabled;
                        last_valid = 1;
                }
        }

        if (!fix && !aper_enabled)
                return;

        if (!aper_base || !aper_size || aper_base + aper_size > 0x100000000UL)
                fix = 1;

        if (gart_fix_e820 && !fix && aper_enabled) {
                if (e820__mapped_any(aper_base, aper_base + aper_size,
                                    E820_TYPE_RAM)) {
                        /* reserve it, so we can reuse it in second kernel */
                        pr_info("e820: reserve [mem %#010Lx-%#010Lx] for GART\n",
                                aper_base, aper_base + aper_size - 1);
                        e820__range_add(aper_base, aper_size, E820_TYPE_RESERVED);
                        e820__update_table_print();
                }
        }

        if (valid_agp)
                return;

        /* disable them all at first */
        for (i = 0; i < amd_nb_bus_dev_ranges[i].dev_limit; i++) {
                int bus;
                int dev_base, dev_limit;

                bus = amd_nb_bus_dev_ranges[i].bus;
                dev_base = amd_nb_bus_dev_ranges[i].dev_base;
                dev_limit = amd_nb_bus_dev_ranges[i].dev_limit;

                for (slot = dev_base; slot < dev_limit; slot++) {
                        if (!early_is_amd_nb(read_pci_config(bus, slot, 3, 0x00)))
                                continue;

                        ctl = read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL);
                        ctl &= ~GARTEN;
                        write_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL, ctl);
                }
        }

}

static int __initdata printed_gart_size_msg;

int __init gart_iommu_hole_init(void)
{
        u32 agp_aper_base = 0, agp_aper_order = 0;
        u32 aper_size, aper_alloc = 0, aper_order = 0, last_aper_order = 0;
        u64 aper_base, last_aper_base = 0;
        int fix, slot, valid_agp = 0;
        int i, node;

        if (!amd_gart_present())
                return -ENODEV;

        if (gart_iommu_aperture_disabled || !fix_aperture ||
            !early_pci_allowed())
                return -ENODEV;

        pr_info("Checking aperture...\n");

        if (!fallback_aper_force)
                agp_aper_base = search_agp_bridge(&agp_aper_order, &valid_agp);

        fix = 0;
        node = 0;
        for (i = 0; i < amd_nb_bus_dev_ranges[i].dev_limit; i++) {
                int bus;
                int dev_base, dev_limit;
                u32 ctl;

                bus = amd_nb_bus_dev_ranges[i].bus;
                dev_base = amd_nb_bus_dev_ranges[i].dev_base;
                dev_limit = amd_nb_bus_dev_ranges[i].dev_limit;

                for (slot = dev_base; slot < dev_limit; slot++) {
                        if (!early_is_amd_nb(read_pci_config(bus, slot, 3, 0x00)))
                                continue;

                        iommu_detected = 1;
                        gart_iommu_aperture = 1;
                        x86_init.iommu.iommu_init = gart_iommu_init;

                        ctl = read_pci_config(bus, slot, 3,
                                              AMD64_GARTAPERTURECTL);

                        /*
                         * Before we do anything else disable the GART. It may
                         * still be enabled if we boot into a crash-kernel here.
                         * Reconfiguring the GART while it is enabled could have
                         * unknown side-effects.
                         */
                        ctl &= ~GARTEN;
                        write_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL, ctl);

                        aper_order = (ctl >> 1) & 7;
                        aper_size = (32 * 1024 * 1024) << aper_order;
                        aper_base = read_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE) & 0x7fff;
                        aper_base <<= 25;

                        pr_info("Node %d: aperture [bus addr %#010Lx-%#010Lx] (%uMB)\n",
                                node, aper_base, aper_base + aper_size - 1,
                                aper_size >> 20);
                        node++;

                        if (!aperture_valid(aper_base, aper_size, 64<<20)) {
                                if (valid_agp && agp_aper_base &&
                                    agp_aper_base == aper_base &&
                                    agp_aper_order == aper_order) {
                                        /* the same between two setting from NB and agp */
                                        if (!no_iommu &&
                                            max_pfn > MAX_DMA32_PFN &&
                                            !printed_gart_size_msg) {
                                                pr_err("you are using iommu with agp, but GART size is less than 64MB\n");
                                                pr_err("please increase GART size in your BIOS setup\n");
                                                pr_err("if BIOS doesn't have that option, contact your HW vendor!\n");
                                                printed_gart_size_msg = 1;
                                        }
                                } else {
                                        fix = 1;
                                        goto out;
                                }
                        }

                        if ((last_aper_order && aper_order != last_aper_order) ||
                            (last_aper_base && aper_base != last_aper_base)) {
                                fix = 1;
                                goto out;
                        }
                        last_aper_order = aper_order;
                        last_aper_base = aper_base;
                }
        }

out:
        if (!fix && !fallback_aper_force) {
                if (last_aper_base) {
                        /*
                         * If this is the kdump kernel, the first kernel
                         * may have allocated the range over its e820 RAM
                         * and fixed up the northbridge
                         */
                        exclude_from_core(last_aper_base, last_aper_order);

                        return 1;
                }
                return 0;
        }

        if (!fallback_aper_force) {
                aper_alloc = agp_aper_base;
                aper_order = agp_aper_order;
        }

        if (aper_alloc) {
                /* Got the aperture from the AGP bridge */
        } else if ((!no_iommu && max_pfn > MAX_DMA32_PFN) ||
                   force_iommu ||
                   valid_agp ||
                   fallback_aper_force) {
                pr_info("Your BIOS doesn't leave an aperture memory hole\n");
                pr_info("Please enable the IOMMU option in the BIOS setup\n");
                pr_info("This costs you %dMB of RAM\n",
                        32 << fallback_aper_order);

                aper_order = fallback_aper_order;
                aper_alloc = allocate_aperture();
                if (!aper_alloc) {
                        /*
                         * Could disable AGP and IOMMU here, but it's
                         * probably not worth it. But the later users
                         * cannot deal with bad apertures and turning
                         * on the aperture over memory causes very
                         * strange problems, so it's better to panic
                         * early.
                         */
                        panic("Not enough memory for aperture");
                }
        } else {
                return 0;
        }

        /*
         * If this is the kdump kernel _and_ the first kernel did not
         * configure the aperture in the northbridge, this range may
         * overlap with the first kernel's memory. We can't access the
         * range through vmcore even though it should be part of the dump.
         */
        exclude_from_core(aper_alloc, aper_order);

        /* Fix up the north bridges */
        for (i = 0; i < amd_nb_bus_dev_ranges[i].dev_limit; i++) {
                int bus, dev_base, dev_limit;

                /*
                 * Don't enable translation yet but enable GART IO and CPU
                 * accesses and set DISTLBWALKPRB since GART table memory is UC.
                 */
                u32 ctl = aper_order << 1;

                bus = amd_nb_bus_dev_ranges[i].bus;
                dev_base = amd_nb_bus_dev_ranges[i].dev_base;
                dev_limit = amd_nb_bus_dev_ranges[i].dev_limit;
                for (slot = dev_base; slot < dev_limit; slot++) {
                        if (!early_is_amd_nb(read_pci_config(bus, slot, 3, 0x00)))
                                continue;

                        write_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL, ctl);
                        write_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE, aper_alloc >> 25);
                }
        }

        set_up_gart_resume(aper_order, aper_alloc);

        return 1;
}