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x86/PCI: ACPI based PCI gap calculation 

Using ACPI to find free address space allows us to find a gap for the
unallocated PCI resources or MMIO resources for hotplug devices within
the BIOS allowed PCI regions.

It works by evaluating the _CRS object under PCI0 looking for producer
resources.  Then searches the e820 memory space for a gap within these
producer resources.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
wifi-calibration
Alok Kataria 2008-07-15 11:59:42 -07:00 committed by Jesse Barnes
parent c300bd2fb5
commit 809d9a8f93
1 changed files with 80 additions and 0 deletions
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80
arch/x86/pci/acpi.c
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@ -4,6 +4,7 @@
#include <linux/irq.h>
#include <linux/dmi.h>
#include <asm/numa.h>
#include <asm/e820.h>
#include "pci.h"
struct pci_root_info {
@ -14,6 +15,11 @@ struct pci_root_info {
int busnum;
};
struct gap_info {
unsigned long gapstart;
unsigned long gapsize;
};
static acpi_status
resource_to_addr(struct acpi_resource *resource,
struct acpi_resource_address64 *addr)
@ -110,6 +116,78 @@ adjust_transparent_bridge_resources(struct pci_bus *bus)
}
}
static acpi_status search_gap(struct acpi_resource *resource, void *data)
{
struct acpi_resource_address64 addr;
acpi_status status;
struct gap_info *gap = data;
unsigned long long start_addr, end_addr;
status = resource_to_addr(resource, &addr);
if (ACPI_SUCCESS(status) &&
addr.resource_type == ACPI_MEMORY_RANGE &&
addr.address_length > gap->gapsize) {
start_addr = addr.minimum + addr.translation_offset;
/*
* We want space only in the 32bit address range
*/
if (start_addr < UINT_MAX) {
end_addr = start_addr + addr.address_length;
e820_search_gap(&gap->gapstart, &gap->gapsize,
start_addr, end_addr);
}
}
return AE_OK;
}
/*
* Search for a hole in the 32 bit address space for PCI to assign MMIO
* resources, for hotplug or unconfigured resources.
* We query the CRS object of the PCI root device to look for possible producer
* resources in the tree and consider these while calulating the start address
* for this hole.
*/
static void pci_setup_gap(acpi_handle *handle)
{
struct gap_info gap;
acpi_status status;
gap.gapstart = 0;
gap.gapsize = 0x400000;
status = acpi_walk_resources(handle, METHOD_NAME__CRS,
search_gap, &gap);
if (ACPI_SUCCESS(status)) {
unsigned long round;
if (!gap.gapstart) {
printk(KERN_ERR "ACPI: Warning: Cannot find a gap "
"in the 32bit address range for PCI\n"
"ACPI: PCI devices may collide with "
"hotpluggable memory address range\n");
}
/*
* Round the gapstart, uses the same logic as in
* e820_gap_setup
*/
round = 0x100000;
while ((gap.gapsize >> 4) > round)
round += round;
/* Fun with two's complement */
pci_mem_start = (gap.gapstart + round) & -round;
printk(KERN_INFO "ACPI: PCI resources should "
"start at %lx (gap: %lx:%lx)\n",
pci_mem_start, gap.gapstart, gap.gapsize);
} else {
printk(KERN_ERR "ACPI: Error while searching for gap in "
"the 32bit address range for PCI\n");
}
}
static void
get_current_resources(struct acpi_device *device, int busnum,
int domain, struct pci_bus *bus)
@ -215,6 +293,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
if (bus && (pci_probe & PCI_USE__CRS))
get_current_resources(device, busnum, domain, bus);
pci_setup_gap(device->handle);
return bus;
}