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Date: Tue, 15 Jul 2008 11:59:42 -0700
From: Alok Kataria <akataria@...are.com>
To: ak@...ux.intel.com, Ingo Molnar <mingo@...e.hu>,
"Brown, Len" <len.brown@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
linux-acpi <linux-acpi@...r.kernel.org>
Subject: acpi based pci gap calculation - v3
Hi Andi,
I don't see this patch being applied in any of the tree yet.
Resending this incase you guys might have missed it.
I assume this will go through the ACPI tree.
The need for this patch was explained in
http://marc.info/?l=linux-kernel&m=121441818818598&w=2
The v2 patch was discussed in
http://marc.info/?l=linux-acpi&m=121433339619175&w=2
I then sent a incremental patch on top of v2 to fix some conditions and
handle the change in the e820_search_gap interface.
In this v3 patch, i have folded the incremental fix into the v2 patch.
Please apply this.
Thanks,
Alok
--
acpi based pci gap calculation - v3
From: Alok N Kataria <akataria@...are.com>
Evaluates the _CRS object under PCI0 looking for producer resources.
Then searches the e820 memory space for a gap within these producer resources.
Allows us to find a gap for the unclaimed pci resources or MMIO resources
for hotplug devices within the BIOS allowed pci regions.
v1->v2: Some changes in the print strings.
Also note the prototype for e820_search_gap has changed in this
iteration, but the return value is ignored while calling it over here.
v2->v3: Pass the pci producer resources end_addr (got from _CRS) to the
e820_search_gap function.
We limit the search only within the producer region's address space.
Also add a condition to check if the resource lies in the 32bit
address range.
Signed-off-by: Alok N Kataria <akataria@...are.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Len Brown <lenb@...nel.org>
Cc: Ingo Molnar <mingo@...e.hu>
---
arch/x86/pci/acpi.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 80 insertions(+), 0 deletions(-)
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 19af069..fff2c42 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -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)
@@ -220,6 +298,8 @@ 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;
}
--
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