kernel-ark/arch/x86_64/kernel/aperture.c
Andi Kleen ece90303ec [PATCH] x86_64: Use the e820 hole to map the IOMMU/AGP aperture
This might save memory on some Opteron systems without AGP bridge.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16 15:25:13 -07:00

306 lines
8.3 KiB
C

/*
* Firmware replacement code.
*
* Work around broken BIOSes that don't set an aperture or only set the
* aperture in the AGP bridge.
* 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.
* $Id: aperture.c,v 1.7 2003/08/01 03:36:18 ak Exp $
*/
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/mmzone.h>
#include <linux/pci_ids.h>
#include <linux/pci.h>
#include <linux/bitops.h>
#include <asm/e820.h>
#include <asm/io.h>
#include <asm/proto.h>
#include <asm/pci-direct.h>
int iommu_aperture;
int iommu_aperture_disabled __initdata = 0;
int iommu_aperture_allowed __initdata = 0;
int fallback_aper_order __initdata = 1; /* 64MB */
int fallback_aper_force __initdata = 0;
int fix_aperture __initdata = 1;
#define NB_ID_3 (PCI_VENDOR_ID_AMD | (0x1103<<16))
static struct resource aper_res = {
.name = "Aperture",
.flags = IORESOURCE_MEM,
};
static u32 __init allocate_aperture(void)
{
#ifdef CONFIG_DISCONTIGMEM
pg_data_t *nd0 = NODE_DATA(0);
#else
pg_data_t *nd0 = &contig_page_data;
#endif
u32 aper_size;
void *p;
if (fallback_aper_order > 7)
fallback_aper_order = 7;
aper_size = (32 * 1024 * 1024) << fallback_aper_order;
/*
* Aperture has to be naturally aligned. This means an 2GB
* aperture won't have much chances to find a place in the
* lower 4GB of memory. Unfortunately we cannot move it up
* because that would make the IOMMU useless.
*/
/* First try to find some free unused space */
if (!allocate_resource(&iomem_resource, &aper_res,
aper_size,
0, 0xffffffff,
aper_size,
NULL, NULL)) {
printk(KERN_INFO "Putting aperture at %lx-%lx\n",
aper_res.start, aper_res.end);
return aper_res.start;
}
/* No free space found. Go on to waste some memory... */
p = __alloc_bootmem_node(nd0, aper_size, aper_size, 0);
if (!p || __pa(p)+aper_size > 0xffffffff) {
printk("Cannot allocate aperture memory hole (%p,%uK)\n",
p, aper_size>>10);
if (p)
free_bootmem_node(nd0, (unsigned long)p, aper_size);
return 0;
}
printk("Mapping aperture over %d KB of precious RAM @ %lx\n",
aper_size >> 10, __pa(p));
return (u32)__pa(p);
}
static int __init aperture_valid(char *name, u64 aper_base, u32 aper_size)
{
if (!aper_base)
return 0;
if (aper_size < 64*1024*1024) {
printk("Aperture from %s too small (%d MB)\n", name, aper_size>>20);
return 0;
}
if (aper_base + aper_size >= 0xffffffff) {
printk("Aperture from %s beyond 4GB. Ignoring.\n",name);
return 0;
}
if (e820_mapped(aper_base, aper_base + aper_size, E820_RAM)) {
printk("Aperture from %s pointing to e820 RAM. Ignoring.\n",name);
return 0;
}
/* Don't check the resource here because the aperture is usually
in an e820 reserved area, and we allocated these earlier. */
return 1;
}
/*
* Find a PCI capability.
* This code runs before the PCI subsystem is initialized, so just
* access the northbridge directly.
*/
static __u32 __init find_cap(int num, int slot, int func, int cap)
{
u8 pos;
int bytes;
if (!(read_pci_config_16(num,slot,func,PCI_STATUS) & PCI_STATUS_CAP_LIST))
return 0;
pos = read_pci_config_byte(num,slot,func,PCI_CAPABILITY_LIST);
for (bytes = 0; bytes < 48 && pos >= 0x40; bytes++) {
u8 id;
pos &= ~3;
id = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_ID);
if (id == 0xff)
break;
if (id == cap)
return pos;
pos = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_NEXT);
}
return 0;
}
/* Read a standard AGPv3 bridge header */
static __u32 __init read_agp(int num, int slot, int func, int cap, u32 *order)
{
u32 apsize;
u32 apsizereg;
int nbits;
u32 aper_low, aper_hi;
u64 aper;
printk("AGP bridge at %02x:%02x:%02x\n", num, slot, func);
apsizereg = read_pci_config_16(num,slot,func, cap + 0x14);
if (apsizereg == 0xffffffff) {
printk("APSIZE in AGP bridge unreadable\n");
return 0;
}
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(num,slot,func, 0x10);
aper_hi = read_pci_config(num,slot,func,0x14);
aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32);
printk("Aperture from AGP @ %Lx size %u MB (APSIZE %x)\n",
aper, 32 << *order, apsizereg);
if (!aperture_valid("AGP bridge", aper, (32*1024*1024) << *order))
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 K8 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 num, slot, func;
/* Poor man's PCI discovery */
for (num = 0; num < 32; num++) {
for (slot = 0; slot < 32; slot++) {
for (func = 0; func < 8; func++) {
u32 class, cap;
u8 type;
class = read_pci_config(num,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(num,slot,func,PCI_CAP_ID_AGP);
if (!cap)
break;
*valid_agp = 1;
return read_agp(num,slot,func,cap,order);
}
/* No multi-function device? */
type = read_pci_config_byte(num,slot,func,
PCI_HEADER_TYPE);
if (!(type & 0x80))
break;
}
}
}
printk("No AGP bridge found\n");
return 0;
}
void __init iommu_hole_init(void)
{
int fix, num;
u32 aper_size, aper_alloc = 0, aper_order, last_aper_order = 0;
u64 aper_base, last_aper_base = 0;
int valid_agp = 0;
if (iommu_aperture_disabled || !fix_aperture)
return;
printk("Checking aperture...\n");
fix = 0;
for (num = 24; num < 32; num++) {
char name[30];
if (read_pci_config(0, num, 3, 0x00) != NB_ID_3)
continue;
iommu_aperture = 1;
aper_order = (read_pci_config(0, num, 3, 0x90) >> 1) & 7;
aper_size = (32 * 1024 * 1024) << aper_order;
aper_base = read_pci_config(0, num, 3, 0x94) & 0x7fff;
aper_base <<= 25;
printk("CPU %d: aperture @ %Lx size %u MB\n", num-24,
aper_base, aper_size>>20);
sprintf(name, "northbridge cpu %d", num-24);
if (!aperture_valid(name, aper_base, aper_size)) {
fix = 1;
break;
}
if ((last_aper_order && aper_order != last_aper_order) ||
(last_aper_base && aper_base != last_aper_base)) {
fix = 1;
break;
}
last_aper_order = aper_order;
last_aper_base = aper_base;
}
if (!fix && !fallback_aper_force)
return;
if (!fallback_aper_force)
aper_alloc = search_agp_bridge(&aper_order, &valid_agp);
if (aper_alloc) {
/* Got the aperture from the AGP bridge */
} else if ((!no_iommu && end_pfn >= 0xffffffff>>PAGE_SHIFT) ||
force_iommu ||
valid_agp ||
fallback_aper_force) {
printk("Your BIOS doesn't leave a aperture memory hole\n");
printk("Please enable the IOMMU option in the BIOS setup\n");
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;
}
/* Fix up the north bridges */
for (num = 24; num < 32; num++) {
if (read_pci_config(0, num, 3, 0x00) != NB_ID_3)
continue;
/* Don't enable translation yet. That is done later.
Assume this BIOS didn't initialise the GART so
just overwrite all previous bits */
write_pci_config(0, num, 3, 0x90, aper_order<<1);
write_pci_config(0, num, 3, 0x94, aper_alloc>>25);
}
}