/*
 *      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/pci.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/errno.h>

#include "pci.h"

/*
 * 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..
 */
void
pcibios_align_resource(void *data, struct resource *res,
                        resource_size_t size, resource_size_t align)
{
        if (res->flags & IORESOURCE_IO) {
                resource_size_t start = res->start;

                if (start & 0x300) {
                        start = (start + 0x3ff) & ~0x3ff;
                        res->start = start;
                }
        }
}


/*
 *  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)
 *
 *  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 __init pcibios_allocate_bus_resources(struct list_head *bus_list)
{
        struct pci_bus *bus;
        struct pci_dev *dev;
        int idx;
        struct resource *r, *pr;

        /* Depth-First Search on bus tree */
        list_for_each_entry(bus, bus_list, node) {
                if ((dev = bus->self)) {
                        for (idx = PCI_BRIDGE_RESOURCES;
                            idx < PCI_NUM_RESOURCES; idx++) {
                                r = &dev->resource[idx];
                                if (!r->flags)
                                        continue;
                                pr = pci_find_parent_resource(dev, r);
                                if (!r->start || !pr ||
                                    request_resource(pr, r) < 0) {
                                        printk(KERN_ERR "PCI: Cannot allocate "
                                                "resource region %d "
                                                "of bridge %s\n",
                                                idx, pci_name(dev));
                                        /*
                                         * Something is wrong with the region.
                                         * Invalidate the resource to prevent
                                         * child resource allocations in this
                                         * range.
                                         */
                                        r->flags = 0;
                                }
                        }
                }
                pcibios_allocate_bus_resources(&bus->children);
        }
}

static void __init pcibios_allocate_resources(int pass)
{
        struct pci_dev *dev = NULL;
        int idx, disabled;
        u16 command;
        struct resource *r, *pr;

        for_each_pci_dev(dev) {
                pci_read_config_word(dev, PCI_COMMAND, &command);
                for (idx = 0; idx < PCI_ROM_RESOURCE; 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) {
                                DBG("PCI: Resource %08lx-%08lx "
                                    "(f=%lx, d=%d, p=%d)\n",
                                    r->start, r->end, r->flags, disabled, pass);
                                pr = pci_find_parent_resource(dev, r);
                                if (!pr || request_resource(pr, r) < 0) {
                                        printk(KERN_ERR "PCI: Cannot allocate "
                                                "resource region %d "
                                                "of device %s\n",
                                                idx, pci_name(dev));
                                        /* We'll assign a new address later */
                                        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;
                                DBG("PCI: Switching off ROM of %s\n",
                                        pci_name(dev));
                                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 int __init pcibios_assign_resources(void)
{
        struct pci_dev *dev = NULL;
        struct resource *r, *pr;

        if (!(pci_probe & PCI_ASSIGN_ROMS)) {
                /*
                 * Try to use BIOS settings for ROMs, otherwise let
                 * pci_assign_unassigned_resources() allocate the new
                 * addresses.
                 */
                for_each_pci_dev(dev) {
                        r = &dev->resource[PCI_ROM_RESOURCE];
                        if (!r->flags || !r->start)
                                continue;
                        pr = pci_find_parent_resource(dev, r);
                        if (!pr || request_resource(pr, r) < 0) {
                                r->end -= r->start;
                                r->start = 0;
                        }
                }
        }

        pci_assign_unassigned_resources();

        return 0;
}

void __init pcibios_resource_survey(void)
{
        DBG("PCI: Allocating resources\n");
        pcibios_allocate_bus_resources(&pci_root_buses);
        pcibios_allocate_resources(0);
        pcibios_allocate_resources(1);
}

/**
 * called in fs_initcall (one below subsys_initcall),
 * give a chance for motherboard reserve resources
 */
fs_initcall(pcibios_assign_resources);

int pcibios_enable_resources(struct pci_dev *dev, int mask)
{
        u16 cmd, old_cmd;
        int idx;
        struct resource *r;

        pci_read_config_word(dev, PCI_COMMAND, &cmd);
        old_cmd = cmd;
        for (idx = 0; idx < PCI_NUM_RESOURCES; idx++) {
                /* Only set up the requested stuff */
                if (!(mask & (1 << idx)))
                        continue;

                r = &dev->resource[idx];
                if (!(r->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
                        continue;
                if ((idx == PCI_ROM_RESOURCE) &&
                                (!(r->flags & IORESOURCE_ROM_ENABLE)))
                        continue;
                if (!r->start && r->end) {
                        printk(KERN_ERR "PCI: Device %s not available "
                                "because of resource %d collisions\n",
                                pci_name(dev), idx);
                        return -EINVAL;
                }
                if (r->flags & IORESOURCE_IO)
                        cmd |= PCI_COMMAND_IO;
                if (r->flags & IORESOURCE_MEM)
                        cmd |= PCI_COMMAND_MEMORY;
        }
        if (cmd != old_cmd) {
                printk("PCI: Enabling device %s (%04x -> %04x)\n",
                        pci_name(dev), old_cmd, cmd);
                pci_write_config_word(dev, PCI_COMMAND, cmd);
        }
        return 0;
}

/*
 *  If we set up a device for bus mastering, we need to check the latency
 *  timer as certain crappy BIOSes forget to set it properly.
 */
unsigned int pcibios_max_latency = 255;

void pcibios_set_master(struct pci_dev *dev)
{
        u8 lat;
        pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
        if (lat < 16)
                lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
        else if (lat > pcibios_max_latency)
                lat = pcibios_max_latency;
        else
                return;
        printk(KERN_DEBUG "PCI: Setting latency timer of device %s to %d\n",
                pci_name(dev), lat);
        pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
}

int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
                        enum pci_mmap_state mmap_state, int write_combine)
{
        unsigned long prot;

        /* I/O space cannot be accessed via normal processor loads and
         * stores on this platform.
         */
        if (mmap_state == pci_mmap_io)
                return -EINVAL;

        /* Leave vm_pgoff as-is, the PCI space address is the physical
         * address on this platform.
         */
        prot = pgprot_val(vma->vm_page_prot);
        if (boot_cpu_data.x86 > 3)
                prot |= _PAGE_PCD | _PAGE_PWT;
        vma->vm_page_prot = __pgprot(prot);

        /* Write-combine setting is ignored, it is changed via the mtrr
         * interfaces on this platform.
         */
        if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
                               vma->vm_end - vma->vm_start,
                               vma->vm_page_prot))
                return -EAGAIN;

        return 0;
}