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Message-Id: <1213916286.27983.37.camel@promb-2n-dhcp368.eng.vmware.com>
Date: Thu, 19 Jun 2008 15:58:06 -0700
From: Alok Kataria <akataria@...are.com>
To: "Brown, Len" <len.brown@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-acpi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] acpi based pci gap caluculation
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.
Signed-off-by: Alok N Kataria <akataria@...are.com>
Index: linux-2.6/arch/x86/pci/acpi.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/acpi.c 2008-06-13 13:58:53.000000000 -0700
+++ linux-2.6/arch/x86/pci/acpi.c 2008-06-13 14:10:05.000000000 -0700
@@ -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 @@
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 +116,70 @@
}
}
+static acpi_status search_gap(struct acpi_resource *resource, void *data)
+{
+ struct acpi_resource_address64 addr;
+ acpi_status status;
+ struct gap_info *gap = data;
+
+ status = resource_to_addr(resource, &addr);
+ if (ACPI_SUCCESS(status) &&
+ addr.resource_type == ACPI_MEMORY_RANGE &&
+ addr.address_length > gap->gapsize) {
+ e820_search_gap(&gap->gapstart, &gap->gapsize,
+ (addr.minimum + addr.translation_offset));
+ }
+
+ 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_PCI: Warning: Cannot find a gap "
+ "in the 32bit address range\n"
+ "ACPI_PCI: May collide with the "
+ "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: PCI resources should "
+ "start at %lx (gap: %lx:%lx)\n",
+ pci_mem_start, gap.gapstart, gap.gapsize);
+ } else {
+ printk(KERN_ERR "ACPI_PCI: 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 +285,8 @@
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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