/* pci-frv.c: low-level PCI access routines
 *
 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * - Derived from the i386 equivalent stuff
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#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-frv.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 list_head *ln;
        struct pci_bus *bus;
        struct pci_dev *dev;
        int idx;
        struct resource *r;

        /* Depth-First Search on bus tree */
        for (ln=bus_list->next; ln != bus_list; ln=ln->next) {
                bus = pci_bus_b(ln);
                if ((dev = bus->self)) {
                        for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_NUM_RESOURCES; idx++) {
                                r = &dev->resource[idx];
                                if (!r->start)
                                        continue;
                                if (pci_claim_resource(dev, idx) < 0)
                                        printk(KERN_ERR "PCI: Cannot allocate resource region %d of bridge %s\n", idx, pci_name(dev));
                        }
                }
                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;

        for_each_pci_dev(dev) {
                pci_read_config_word(dev, PCI_COMMAND, &command);
                for(idx = 0; idx < 6; 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);
                                if (pci_claim_resource(dev, idx) < 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 void __init pcibios_assign_resources(void)
{
        struct pci_dev *dev = NULL;
        int idx;
        struct resource *r;

        for_each_pci_dev(dev) {
                int class = dev->class >> 8;

                /* Don't touch classless devices and host bridges */
                if (!class || class == PCI_CLASS_BRIDGE_HOST)
                        continue;

                for(idx=0; idx<6; idx++) {
                        r = &dev->resource[idx];

                        /*
                         *  Don't touch IDE controllers and I/O ports of video cards!
                         */
                        if ((class == PCI_CLASS_STORAGE_IDE && idx < 4) ||
                            (class == PCI_CLASS_DISPLAY_VGA && (r->flags & IORESOURCE_IO)))
                                continue;

                        /*
                         *  We shall assign a new address to this resource, either because
                         *  the BIOS forgot to do so or because we have decided the old
                         *  address was unusable for some reason.
                         */
                        if (!r->start && r->end)
                                pci_assign_resource(dev, idx);
                }

                if (pci_probe & PCI_ASSIGN_ROMS) {
                        r = &dev->resource[PCI_ROM_RESOURCE];
                        r->end -= r->start;
                        r->start = 0;
                        if (r->end)
                                pci_assign_resource(dev, PCI_ROM_RESOURCE);
                }
        }
}

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);
        pcibios_assign_resources();
}

/*
 *  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);
}