/*
* 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, ®);
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;
}
