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authorAlok Kataria <akataria@vmware.com>2008-07-15 14:59:42 -0400
committerJesse Barnes <jbarnes@virtuousgeek.org>2008-07-15 18:49:03 -0400
commit809d9a8f93bd8504dcc34b16bbfdfd1a8c9bb1ed (patch)
tree52a090a2a10a126f3b4762fd6c98d58f5441a6d0 /arch
parentc300bd2fb583afb6d68804afd38bc90b31310d95 (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/pci/acpi.c80
1 files changed, 80 insertions, 0 deletions
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index d95de2f199cd..d1ffb5709174 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -4,6 +4,7 @@
4#include <linux/irq.h> 4#include <linux/irq.h>
5#include <linux/dmi.h> 5#include <linux/dmi.h>
6#include <asm/numa.h> 6#include <asm/numa.h>
7#include <asm/e820.h>
7#include "pci.h" 8#include "pci.h"
8 9
9struct pci_root_info { 10struct pci_root_info {
@@ -14,6 +15,11 @@ struct pci_root_info {
14 int busnum; 15 int busnum;
15}; 16};
16 17
18struct gap_info {
19 unsigned long gapstart;
20 unsigned long gapsize;
21};
22
17static acpi_status 23static acpi_status
18resource_to_addr(struct acpi_resource *resource, 24resource_to_addr(struct acpi_resource *resource,
19 struct acpi_resource_address64 *addr) 25 struct acpi_resource_address64 *addr)
@@ -110,6 +116,78 @@ adjust_transparent_bridge_resources(struct pci_bus *bus)
110 } 116 }
111} 117}
112 118
119static acpi_status search_gap(struct acpi_resource *resource, void *data)
120{
121 struct acpi_resource_address64 addr;
122 acpi_status status;
123 struct gap_info *gap = data;
124 unsigned long long start_addr, end_addr;
125
126 status = resource_to_addr(resource, &addr);
127 if (ACPI_SUCCESS(status) &&
128 addr.resource_type == ACPI_MEMORY_RANGE &&
129 addr.address_length > gap->gapsize) {
130 start_addr = addr.minimum + addr.translation_offset;
131 /*
132 * We want space only in the 32bit address range
133 */
134 if (start_addr < UINT_MAX) {
135 end_addr = start_addr + addr.address_length;
136 e820_search_gap(&gap->gapstart, &gap->gapsize,
137 start_addr, end_addr);
138 }
139 }
140
141 return AE_OK;
142}
143
144/*
145 * Search for a hole in the 32 bit address space for PCI to assign MMIO
146 * resources, for hotplug or unconfigured resources.
147 * We query the CRS object of the PCI root device to look for possible producer
148 * resources in the tree and consider these while calulating the start address
149 * for this hole.
150 */
151static void pci_setup_gap(acpi_handle *handle)
152{
153 struct gap_info gap;
154 acpi_status status;
155
156 gap.gapstart = 0;
157 gap.gapsize = 0x400000;
158
159 status = acpi_walk_resources(handle, METHOD_NAME__CRS,
160 search_gap, &gap);
161
162 if (ACPI_SUCCESS(status)) {
163 unsigned long round;
164
165 if (!gap.gapstart) {
166 printk(KERN_ERR "ACPI: Warning: Cannot find a gap "
167 "in the 32bit address range for PCI\n"
168 "ACPI: PCI devices may collide with "
169 "hotpluggable memory address range\n");
170 }
171 /*
172 * Round the gapstart, uses the same logic as in
173 * e820_gap_setup
174 */
175 round = 0x100000;
176 while ((gap.gapsize >> 4) > round)
177 round += round;
178 /* Fun with two's complement */
179 pci_mem_start = (gap.gapstart + round) & -round;
180
181 printk(KERN_INFO "ACPI: PCI resources should "
182 "start at %lx (gap: %lx:%lx)\n",
183 pci_mem_start, gap.gapstart, gap.gapsize);
184 } else {
185 printk(KERN_ERR "ACPI: Error while searching for gap in "
186 "the 32bit address range for PCI\n");
187 }
188}
189
190
113static void 191static void
114get_current_resources(struct acpi_device *device, int busnum, 192get_current_resources(struct acpi_device *device, int busnum,
115 int domain, struct pci_bus *bus) 193 int domain, struct pci_bus *bus)
@@ -215,6 +293,8 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
215 293
216 if (bus && (pci_probe & PCI_USE__CRS)) 294 if (bus && (pci_probe & PCI_USE__CRS))
217 get_current_resources(device, busnum, domain, bus); 295 get_current_resources(device, busnum, domain, bus);
296
297 pci_setup_gap(device->handle);
218 return bus; 298 return bus;
219} 299}
220 300