PCI: skip ISA ioresource alignment on some systems

Skip ISA ioresource alignment on some systems

To conserve limited PCI i/o resource on some IBM multi-node systems, the
BIOS allocates (via _CRS) and expects the kernel to use addresses in
ranges currently excluded by pcibios_align_resource() [i386/pci/i386.c].
This change allows the kernel to use the currently excluded address
ranges on the IBM x3800, x3850, and x3950.

Signed-off-by: Gary Hade <gary.hade@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/pci/acpi.c

@@ -2,15 +2,57 @@
 #include <linux/acpi.h>
 #include <linux/init.h>
 #include <linux/irq.h>
+#include <linux/dmi.h>
 #include <asm/numa.h>
 #include "pci.h"
 
+static int __devinit can_skip_ioresource_align(struct dmi_system_id *d)
+{
+	pci_probe |= PCI_CAN_SKIP_ISA_ALIGN;
+	printk(KERN_INFO "PCI: %s detected, can skip ISA alignment\n", d->ident);
+	return 0;
+}
+
+static struct dmi_system_id acpi_pciprobe_dmi_table[] = {
+/*
+ * Systems where PCI IO resource ISA alignment can be skipped
+ * when the ISA enable bit in the bridge control is not set
+ */
+	{
+		.callback = can_skip_ioresource_align,
+		.ident = "IBM System x3800",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IBM"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "x3800"),
+		},
+	},
+	{
+		.callback = can_skip_ioresource_align,
+		.ident = "IBM System x3850",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IBM"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "x3850"),
+		},
+	},
+	{
+		.callback = can_skip_ioresource_align,
+		.ident = "IBM System x3950",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IBM"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "x3950"),
+		},
+	},
+	{}
+};
+
 struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int domain, int busnum)
 {
 	struct pci_bus *bus;
 	struct pci_sysdata *sd;
 	int pxm;
 
+	dmi_check_system(acpi_pciprobe_dmi_table);
+
 	/* Allocate per-root-bus (not per bus) arch-specific data.
 	 * TODO: leak; this memory is never freed.
 	 * It's arguable whether it's worth the trouble to care.

arch/x86/pci/i386.c

@@ -33,6 +33,15 @@
 
 #include "pci.h"
 
+static int
+skip_isa_ioresource_align(struct pci_dev *dev) {
+
+	if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
+	    (dev->bus->bridge_ctl & PCI_BRIDGE_CTL_NO_ISA))
+		return 1;
+	return 0;
+}
+
 /*
  * We need to avoid collisions with `mirrored' VGA ports
  * and other strange ISA hardware, so we always want the
@@ -50,9 +59,13 @@ void
 pcibios_align_resource(void *data, struct resource *res,
 			resource_size_t size, resource_size_t align)
 {
+	struct pci_dev *dev = data;
+
 	if (res->flags & IORESOURCE_IO) {
 		resource_size_t start = res->start;
 
+		if (skip_isa_ioresource_align(dev))
+			return;
 		if (start & 0x300) {
 			start = (start + 0x3ff) & ~0x3ff;
 			res->start = start;

arch/x86/pci/pci.h

@@ -26,6 +26,7 @@
 #define PCI_ASSIGN_ROMS		0x1000
 #define PCI_BIOS_IRQ_SCAN	0x2000
 #define PCI_ASSIGN_ALL_BUSSES	0x4000
+#define PCI_CAN_SKIP_ISA_ALIGN	0x8000
 
 extern unsigned int pci_probe;
 extern unsigned long pirq_table_addr;

drivers/pci/probe.c

@@ -544,7 +544,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max, int pass
 			goto out;
 		child->primary = buses & 0xFF;
 		child->subordinate = (buses >> 16) & 0xFF;
-		child->bridge_ctl = bctl;
+		child->bridge_ctl = bctl ^ PCI_BRIDGE_CTL_NO_ISA;
 
 		cmax = pci_scan_child_bus(child);
 		if (cmax > max)
@@ -597,7 +597,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max, int pass
 		pci_write_config_dword(dev, PCI_PRIMARY_BUS, buses);
 
 		if (!is_cardbus) {
-			child->bridge_ctl = bctl | PCI_BRIDGE_CTL_NO_ISA;
+			child->bridge_ctl = bctl ^ PCI_BRIDGE_CTL_NO_ISA;
 			/*
 			 * Adjust subordinate busnr in parent buses.
 			 * We do this before scanning for children because