[PATCH 4/(3+1)] Add quirks for ACPI PCI slot detection driver

[Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>]

ACPI spec says that OSPM checks with the bus driver for _ADR devices
to verify the presence of the device. But there are hardwares that
provide _STA for PCI hotplug slots to indicate the presence of the
device. For those hardwares, we want to ignore _STA and evaluate _SUN
by force, otherwise PCI hotplug slots would not be detected.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

---
 drivers/acpi/pci_slot.c |   47 +++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 4 deletions(-)

Index: linux-2.6.25-rc4/drivers/acpi/pci_slot.c
===================================================================
--- linux-2.6.25-rc4.orig/drivers/acpi/pci_slot.c
+++ linux-2.6.25-rc4/drivers/acpi/pci_slot.c
@@ -31,6 +31,7 @@
 #include <acpi/acpi_drivers.h>
 
 static int debug;
+static int ignore_sta;
 
 #define DRIVER_VERSION 	"0.1"
 #define DRIVER_AUTHOR	"Alex Chiang <achiang@hp.com>"
@@ -73,10 +74,20 @@ check_slot(acpi_handle handle, int *devi
 	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 	dbg("Checking slot on path: %s\n", (char *)buffer.pointer);
 
-	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
-	if (ACPI_SUCCESS(status) && !(sta & ACPI_STA_DEVICE_PRESENT)) {
-		retval = -1;
-		goto out;
+	/*
+	 * ACPI spec says that OSPM checks with the bus driver for
+	 * _ADR devices to verify the presence of the device. But
+	 * there are hardwares that provide _STA for PCI hotplug slots
+	 * to indicate the presence of the device. For those
+	 * hardwares, we want to ignore _STA and evaluate _SUN by
+	 * force, otherwise PCI hotplug slots would not be detected.
+	 */
+	if (!ignore_sta) {
+		status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
+		if (ACPI_SUCCESS(status) && !(sta & ACPI_STA_DEVICE_PRESENT)) {
+			retval = -1;
+			goto out;
+		}
 	}
 
 	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
@@ -311,9 +322,37 @@ acpi_pci_slot_remove(acpi_handle handle)
 		err("%s: unregister_slot failure - %d\n", __FUNCTION__, status);
 }
 
+#ifdef CONFIG_DMI
+static int ignore_sta_before_sun(const struct dmi_system_id *d)
+{
+	info("%s detected: will ignore _STA before calling _SUN\n", d->ident);
+	ignore_sta = 1;
+	return 0;
+}
+
+static struct dmi_system_id acpi_pci_slot_dmi_table[] __initdata = {
+	/*
+	 * Ignore _STA if the hardware provides _STA to indicate the
+	 * presence of PCI adapter card on PCI hotplug slot.
+	 */
+	/* Please add appropriate values for HP/IBM servers.
+	{
+		.callback = ignore_sta_before_sun,
+		.ident = "",
+		.matches = {
+			DMI_MATCH(DMI_BIOS_VENDOR, ""),
+			DMI_MATCH(DMI_BIOS_VERSION, ""),
+		},
+	},
+	*/
+	{}
+};
+#endif /* CONFIG_DMI */
+
 static int __init
 acpi_pci_slot_init(void)
 {
+	dmi_check_system(acpi_pci_slot_dmi_table);
 	acpi_pci_register_driver(&acpi_pci_slot_driver);
 	return 0;
 }