// SPDX-License-Identifier: GPL-2.0
/*
 *      Low-Level PCI Access for i386 machines
 *
 * Copyright 1993, 1994 Drew Eckhardt
 *      Visionary Computing
 *      (Unix and Linux consulting and custom programming)
 *      Drew@Colorado.EDU
 *      +1 (303) 786-7975
 *
 * Drew's work was sponsored by:
 *      iX Multiuser Multitasking Magazine
 *      Hannover, Germany
 *      hm@ix.de
 *
 * Copyright 1997--2000 Martin Mares <mj@ucw.cz>
 *
 * For more information, please consult the following manuals (look at
 * http://www.pcisig.com/ for how to get them):
 *
 * PCI BIOS Specification
 * PCI Local Bus Specification
 * PCI to PCI Bridge Specification
 * PCI System Design Guide
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/errno.h>
#include <linux/memblock.h>

#include <asm/memtype.h>
#include <asm/e820/api.h>
#include <asm/pci_x86.h>
#include <asm/io_apic.h>


/*
 * This list of dynamic mappings is for temporarily maintaining
 * original BIOS BAR addresses for possible reinstatement.
 */
struct pcibios_fwaddrmap {
        struct list_head list;
        struct pci_dev *dev;
        resource_size_t fw_addr[DEVICE_COUNT_RESOURCE];
};

static LIST_HEAD(pcibios_fwaddrmappings);
static DEFINE_SPINLOCK(pcibios_fwaddrmap_lock);
static bool pcibios_fw_addr_done;

/* Must be called with 'pcibios_fwaddrmap_lock' lock held. */
static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev)
{
        struct pcibios_fwaddrmap *map;

        lockdep_assert_held(&pcibios_fwaddrmap_lock);

        list_for_each_entry(map, &pcibios_fwaddrmappings, list)
                if (map->dev == dev)
                        return map;

        return NULL;
}

static void
pcibios_save_fw_addr(struct pci_dev *dev, int idx, resource_size_t fw_addr)
{
        unsigned long flags;
        struct pcibios_fwaddrmap *map;

        if (pcibios_fw_addr_done)
                return;

        spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
        map = pcibios_fwaddrmap_lookup(dev);
        if (!map) {
                spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
                map = kzalloc_obj(*map);
                if (!map)
                        return;

                map->dev = pci_dev_get(dev);
                map->fw_addr[idx] = fw_addr;
                INIT_LIST_HEAD(&map->list);

                spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
                list_add_tail(&map->list, &pcibios_fwaddrmappings);
        } else
                map->fw_addr[idx] = fw_addr;
        spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
}

resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx)
{
        unsigned long flags;
        struct pcibios_fwaddrmap *map;
        resource_size_t fw_addr = 0;

        if (pcibios_fw_addr_done)
                return 0;

        spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
        map = pcibios_fwaddrmap_lookup(dev);
        if (map)
                fw_addr = map->fw_addr[idx];
        spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);

        return fw_addr;
}

static void __init pcibios_fw_addr_list_del(void)
{
        unsigned long flags;
        struct pcibios_fwaddrmap *entry, *next;

        spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
        list_for_each_entry_safe(entry, next, &pcibios_fwaddrmappings, list) {
                list_del(&entry->list);
                pci_dev_put(entry->dev);
                kfree(entry);
        }
        spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
        pcibios_fw_addr_done = true;
}

static int
skip_isa_ioresource_align(struct pci_dev *dev) {

        if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
            !(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
                return 1;
        return 0;
}

/*
 * We need to avoid collisions with `mirrored' VGA ports
 * and other strange ISA hardware, so we always want the
 * addresses to be allocated in the 0x000-0x0ff region
 * modulo 0x400.
 *
 * Why? Because some silly external IO cards only decode
 * the low 10 bits of the IO address. The 0x00-0xff region
 * is reserved for motherboard devices that decode all 16
 * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
 * but we want to try to avoid allocating at 0x2900-0x2bff
 * which might have be mirrored at 0x0100-0x03ff..
 */
resource_size_t
pcibios_align_resource(void *data, const struct resource *res,
                        resource_size_t size, resource_size_t align)
{
        struct pci_dev *dev = data;
        resource_size_t start = res->start;

        if (res->flags & IORESOURCE_IO) {
                if (skip_isa_ioresource_align(dev))
                        return start;
                if (start & 0x300)
                        start = (start + 0x3ff) & ~0x3ff;
        } else if (res->flags & IORESOURCE_MEM) {
                /* The low 1MB range is reserved for ISA cards */
                if (start < BIOS_END)
                        start = BIOS_END;
        }
        return start;
}
EXPORT_SYMBOL(pcibios_align_resource);

/*
 *  Handle resources of PCI devices.  If the world were perfect, we could
 *  just allocate all the resource regions and do nothing more.  It isn't.
 *  On the other hand, we cannot just re-allocate all devices, as it would
 *  require us to know lots of host bridge internals.  So we attempt to
 *  keep as much of the original configuration as possible, but tweak it
 *  when it's found to be wrong.
 *
 *  Known BIOS problems we have to work around:
 *      - I/O or memory regions not configured
 *      - regions configured, but not enabled in the command register
 *      - bogus I/O addresses above 64K used
 *      - expansion ROMs left enabled (this may sound harmless, but given
 *        the fact the PCI specs explicitly allow address decoders to be
 *        shared between expansion ROMs and other resource regions, it's
 *        at least dangerous)
 *      - bad resource sizes or overlaps with other regions
 *
 *  Our solution:
 *      (1) Allocate resources for all buses behind PCI-to-PCI bridges.
 *          This gives us fixed barriers on where we can allocate.
 *      (2) Allocate resources for all enabled devices.  If there is
 *          a collision, just mark the resource as unallocated. Also
 *          disable expansion ROMs during this step.
 *      (3) Try to allocate resources for disabled devices.  If the
 *          resources were assigned correctly, everything goes well,
 *          if they weren't, they won't disturb allocation of other
 *          resources.
 *      (4) Assign new addresses to resources which were either
 *          not configured at all or misconfigured.  If explicitly
 *          requested by the user, configure expansion ROM address
 *          as well.
 */

static void pcibios_allocate_bridge_resources(struct pci_dev *dev)
{
        int idx;
        struct resource *r;

        for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_NUM_RESOURCES; idx++) {
                r = &dev->resource[idx];
                if (!r->flags)
                        continue;
                if (r->parent)  /* Already allocated */
                        continue;
                if (!r->start || pci_claim_bridge_resource(dev, idx) < 0) {
                        /*
                         * Something is wrong with the region.
                         * Invalidate the resource to prevent
                         * child resource allocations in this
                         * range.
                         */
                        r->start = r->end = 0;
                        r->flags = 0;
                }
        }
}

static void pcibios_allocate_bus_resources(struct pci_bus *bus)
{
        struct pci_bus *child;

        /* Depth-First Search on bus tree */
        if (bus->self)
                pcibios_allocate_bridge_resources(bus->self);
        list_for_each_entry(child, &bus->children, node)
                pcibios_allocate_bus_resources(child);
}

struct pci_check_idx_range {
        int start;
        int end;
};

static void pcibios_allocate_dev_resources(struct pci_dev *dev, int pass)
{
        int idx, disabled, i;
        u16 command;
        struct resource *r;

        struct pci_check_idx_range idx_range[] = {
                { PCI_STD_RESOURCES, PCI_STD_RESOURCE_END },
#ifdef CONFIG_PCI_IOV
                { PCI_IOV_RESOURCES, PCI_IOV_RESOURCE_END },
#endif
        };

        pci_read_config_word(dev, PCI_COMMAND, &command);
        for (i = 0; i < ARRAY_SIZE(idx_range); i++)
                for (idx = idx_range[i].start; idx <= idx_range[i].end; idx++) {
                        r = &dev->resource[idx];
                        if (r->parent)  /* Already allocated */
                                continue;
                        if (!r->start)  /* Address not assigned at all */
                                continue;
                        if (r->flags & IORESOURCE_IO)
                                disabled = !(command & PCI_COMMAND_IO);
                        else
                                disabled = !(command & PCI_COMMAND_MEMORY);
                        if (pass == disabled) {
                                dev_dbg(&dev->dev,
                                        "BAR %d: reserving %pr (d=%d, p=%d)\n",
                                        idx, r, disabled, pass);
                                if (pci_claim_resource(dev, idx) < 0) {
                                        if (r->flags & IORESOURCE_PCI_FIXED) {
                                                dev_info(&dev->dev, "BAR %d %pR is immovable\n",
                                                         idx, r);
                                        } else {
                                                /* We'll assign a new address later */
                                                pcibios_save_fw_addr(dev,
                                                                idx, r->start);
                                                r->end -= r->start;
                                                r->start = 0;
                                        }
                                }
                        }
                }
        if (!pass) {
                r = &dev->resource[PCI_ROM_RESOURCE];
                if (r->flags & IORESOURCE_ROM_ENABLE) {
                        /* Turn the ROM off, leave the resource region,
                         * but keep it unregistered. */
                        u32 reg;
                        dev_dbg(&dev->dev, "disabling ROM %pR\n", r);
                        r->flags &= ~IORESOURCE_ROM_ENABLE;
                        pci_read_config_dword(dev, dev->rom_base_reg, &reg);
                        pci_write_config_dword(dev, dev->rom_base_reg,
                                                reg & ~PCI_ROM_ADDRESS_ENABLE);
                }
        }
}

static void pcibios_allocate_resources(struct pci_bus *bus, int pass)
{
        struct pci_dev *dev;
        struct pci_bus *child;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                pcibios_allocate_dev_resources(dev, pass);

                child = dev->subordinate;
                if (child)
                        pcibios_allocate_resources(child, pass);
        }
}

static void pcibios_allocate_dev_rom_resource(struct pci_dev *dev)
{
        struct resource *r;

        /*
         * Try to use BIOS settings for ROMs, otherwise let
         * pci_assign_unassigned_resources() allocate the new
         * addresses.
         */
        r = &dev->resource[PCI_ROM_RESOURCE];
        if (!r->flags || !r->start)
                return;
        if (r->parent) /* Already allocated */
                return;

        if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) {
                r->end -= r->start;
                r->start = 0;
        }
}
static void pcibios_allocate_rom_resources(struct pci_bus *bus)
{
        struct pci_dev *dev;
        struct pci_bus *child;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                pcibios_allocate_dev_rom_resource(dev);

                child = dev->subordinate;
                if (child)
                        pcibios_allocate_rom_resources(child);
        }
}

static int __init pcibios_assign_resources(void)
{
        struct pci_bus *bus;

        if (!(pci_probe & PCI_ASSIGN_ROMS))
                list_for_each_entry(bus, &pci_root_buses, node)
                        pcibios_allocate_rom_resources(bus);

        pci_assign_unassigned_resources();
        pcibios_fw_addr_list_del();

        return 0;
}

/*
 * This is an fs_initcall (one below subsys_initcall) in order to reserve
 * resources properly.
 */
fs_initcall(pcibios_assign_resources);

void pcibios_resource_survey_bus(struct pci_bus *bus)
{
        dev_printk(KERN_DEBUG, &bus->dev, "Allocating resources\n");

        pcibios_allocate_bus_resources(bus);

        pcibios_allocate_resources(bus, 0);
        pcibios_allocate_resources(bus, 1);

        if (!(pci_probe & PCI_ASSIGN_ROMS))
                pcibios_allocate_rom_resources(bus);
}

void __init pcibios_resource_survey(void)
{
        struct pci_bus *bus;

        DBG("PCI: Allocating resources\n");

        list_for_each_entry(bus, &pci_root_buses, node)
                pcibios_allocate_bus_resources(bus);

        list_for_each_entry(bus, &pci_root_buses, node)
                pcibios_allocate_resources(bus, 0);
        list_for_each_entry(bus, &pci_root_buses, node)
                pcibios_allocate_resources(bus, 1);

        e820__reserve_resources_late();
        /*
         * Insert the IO APIC resources after PCI initialization has
         * occurred to handle IO APICS that are mapped in on a BAR in
         * PCI space, but before trying to assign unassigned pci res.
         */
        ioapic_insert_resources();
}