x86/PCI: use host bridge _CRS info by default on 2008 and newer machines

The main benefit of using ACPI host bridge window information is that
we can do better resource allocation in systems with multiple host bridges,
e.g., http://bugzilla.kernel.org/show_bug.cgi?id=14183

Sometimes we need _CRS information even if we only have one host bridge,
e.g., https://bugs.launchpad.net/ubuntu/+source/linux/+bug/341681

Most of these systems are relatively new, so this patch turns on
"pci=use_crs" only on machines with a BIOS date of 2008 or newer.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Documentation/kernel-parameters.txt

@@ -1948,8 +1948,12 @@ and is between 256 and 4096 characters. It is defined in the file
 				IRQ routing is enabled.
 		noacpi		[X86] Do not use ACPI for IRQ routing
 				or for PCI scanning.
-		use_crs		[X86] Use _CRS for PCI resource
+		use_crs		[X86] Use PCI host bridge window information
-				allocation.
+				from ACPI.  On BIOSes from 2008 or later, this
+				is enabled by default.  If you need to use this,
+				please report a bug.
+		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
+			        If you need to use this, please report a bug.
 		routeirq	Do IRQ routing for all PCI devices.
 				This is normally done in pci_enable_device(),
 				so this option is a temporary workaround

arch/ia64/include/asm/acpi.h

@@ -98,6 +98,7 @@ ia64_acpi_release_global_lock (unsigned int *lock)
 #endif
 #define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }
+static inline void pci_acpi_crs_quirks(void) { }
 
 const char *acpi_get_sysname (void);
 int acpi_request_vector (u32 int_type);

arch/x86/include/asm/pci_x86.h

@@ -29,6 +29,7 @@
 #define PCI_CHECK_ENABLE_AMD_MMCONF	0x20000
 #define PCI_HAS_IO_ECS		0x40000
 #define PCI_NOASSIGN_ROMS	0x80000
+#define PCI_ROOT_NO_CRS		0x100000
 
 extern unsigned int pci_probe;
 extern unsigned long pirq_table_addr;

arch/x86/pci/acpi.c

@@ -15,6 +15,51 @@ struct pci_root_info {
 	int busnum;
 };
 
+static bool pci_use_crs = true;
+
+static int __init set_use_crs(const struct dmi_system_id *id)
+{
+	pci_use_crs = true;
+	return 0;
+}
+
+static const struct dmi_system_id pci_use_crs_table[] __initconst = {
+	/* http://bugzilla.kernel.org/show_bug.cgi?id=14183 */
+	{
+		.callback = set_use_crs,
+		.ident = "IBM System x3800",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "IBM"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "x3800"),
+		},
+	},
+	{}
+};
+
+void __init pci_acpi_crs_quirks(void)
+{
+	int year;
+
+	if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year < 2008)
+		pci_use_crs = false;
+
+	dmi_check_system(pci_use_crs_table);
+
+	/*
+	 * If the user specifies "pci=use_crs" or "pci=nocrs" explicitly, that
+	 * takes precedence over anything we figured out above.
+	 */
+	if (pci_probe & PCI_ROOT_NO_CRS)
+		pci_use_crs = false;
+	else if (pci_probe & PCI_USE__CRS)
+		pci_use_crs = true;
+
+	printk(KERN_INFO "PCI: %s host bridge windows from ACPI; "
+	       "if necessary, use \"pci=%s\" and report a bug\n",
+	       pci_use_crs ? "Using" : "Ignoring",
+	       pci_use_crs ? "nocrs" : "use_crs");
+}
+
 static acpi_status
 resource_to_addr(struct acpi_resource *resource,
 			struct acpi_resource_address64 *addr)
@@ -106,7 +151,7 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 	res->child = NULL;
 	align_resource(info->bridge, res);
 
-	if (!(pci_probe & PCI_USE__CRS)) {
+	if (!pci_use_crs) {
 		dev_printk(KERN_DEBUG, &info->bridge->dev,
 			   "host bridge window %pR (ignored)\n", res);
 		return AE_OK;
@@ -137,12 +182,8 @@ get_current_resources(struct acpi_device *device, int busnum,
 	struct pci_root_info info;
 	size_t size;
 
-	if (pci_probe & PCI_USE__CRS)
+	if (pci_use_crs)
 		pci_bus_remove_resources(bus);
-	else
-		dev_info(&device->dev,
-			 "ignoring host bridge windows from ACPI; "
-			 "boot with \"pci=use_crs\" to use them\n");
 
 	info.bridge = device;
 	info.bus = bus;

arch/x86/pci/common.c

@@ -520,6 +520,9 @@ char * __devinit  pcibios_setup(char *str)
 	} else if (!strcmp(str, "use_crs")) {
 		pci_probe |= PCI_USE__CRS;
 		return NULL;
+	} else if (!strcmp(str, "nocrs")) {
+		pci_probe |= PCI_ROOT_NO_CRS;
+		return NULL;
 	} else if (!strcmp(str, "earlydump")) {
 		pci_early_dump_regs = 1;
 		return NULL;

drivers/acpi/pci_root.c

@@ -566,6 +566,7 @@ static int __init acpi_pci_root_init(void)
 	if (acpi_pci_disabled)
 		return 0;
 
+	pci_acpi_crs_quirks();
 	if (acpi_bus_register_driver(&acpi_pci_root_driver) < 0)
 		return -ENODEV;
 

include/acpi/acpi_drivers.h

@@ -104,6 +104,7 @@ int acpi_pci_bind_root(struct acpi_device *device);
 
 struct pci_bus *pci_acpi_scan_root(struct acpi_device *device, int domain,
 				   int bus);
+void pci_acpi_crs_quirks(void);
 
 /* --------------------------------------------------------------------------
                                     Processor