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>
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@ -4,6 +4,7 @@
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#include <linux/irq.h>
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#include <linux/irq.h>
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#include <linux/dmi.h>
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#include <linux/dmi.h>
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#include <asm/numa.h>
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#include <asm/numa.h>
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#include <asm/e820.h>
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#include "pci.h"
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#include "pci.h"
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struct pci_root_info {
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struct pci_root_info {
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@ -14,6 +15,11 @@ struct pci_root_info {
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int busnum;
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int busnum;
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};
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};
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struct gap_info {
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unsigned long gapstart;
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unsigned long gapsize;
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};
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static acpi_status
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static acpi_status
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resource_to_addr(struct acpi_resource *resource,
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resource_to_addr(struct acpi_resource *resource,
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struct acpi_resource_address64 *addr)
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struct acpi_resource_address64 *addr)
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@ -110,6 +116,78 @@ adjust_transparent_bridge_resources(struct pci_bus *bus)
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}
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}
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}
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}
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static acpi_status search_gap(struct acpi_resource *resource, void *data)
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{
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struct acpi_resource_address64 addr;
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acpi_status status;
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struct gap_info *gap = data;
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unsigned long long start_addr, end_addr;
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status = resource_to_addr(resource, &addr);
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if (ACPI_SUCCESS(status) &&
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addr.resource_type == ACPI_MEMORY_RANGE &&
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addr.address_length > gap->gapsize) {
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start_addr = addr.minimum + addr.translation_offset;
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/*
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* We want space only in the 32bit address range
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*/
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if (start_addr < UINT_MAX) {
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end_addr = start_addr + addr.address_length;
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e820_search_gap(&gap->gapstart, &gap->gapsize,
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start_addr, end_addr);
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}
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}
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return AE_OK;
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}
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/*
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* Search for a hole in the 32 bit address space for PCI to assign MMIO
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* resources, for hotplug or unconfigured resources.
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* We query the CRS object of the PCI root device to look for possible producer
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* resources in the tree and consider these while calulating the start address
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* for this hole.
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*/
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static void pci_setup_gap(acpi_handle *handle)
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{
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struct gap_info gap;
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acpi_status status;
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gap.gapstart = 0;
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gap.gapsize = 0x400000;
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status = acpi_walk_resources(handle, METHOD_NAME__CRS,
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search_gap, &gap);
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if (ACPI_SUCCESS(status)) {
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unsigned long round;
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if (!gap.gapstart) {
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printk(KERN_ERR "ACPI: Warning: Cannot find a gap "
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"in the 32bit address range for PCI\n"
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"ACPI: PCI devices may collide with "
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"hotpluggable memory address range\n");
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}
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/*
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* Round the gapstart, uses the same logic as in
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* e820_gap_setup
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*/
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round = 0x100000;
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while ((gap.gapsize >> 4) > round)
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round += round;
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/* Fun with two's complement */
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pci_mem_start = (gap.gapstart + round) & -round;
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printk(KERN_INFO "ACPI: PCI resources should "
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"start at %lx (gap: %lx:%lx)\n",
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pci_mem_start, gap.gapstart, gap.gapsize);
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} else {
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printk(KERN_ERR "ACPI: Error while searching for gap in "
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"the 32bit address range for PCI\n");
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}
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}
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static void
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static void
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get_current_resources(struct acpi_device *device, int busnum,
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get_current_resources(struct acpi_device *device, int busnum,
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int domain, struct pci_bus *bus)
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int domain, struct pci_bus *bus)
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@ -215,6 +293,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
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if (bus && (pci_probe & PCI_USE__CRS))
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if (bus && (pci_probe & PCI_USE__CRS))
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get_current_resources(device, busnum, domain, bus);
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get_current_resources(device, busnum, domain, bus);
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pci_setup_gap(device->handle);
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return bus;
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return bus;
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}
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}
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