[ACPI] workaround for nForce2 BIOS bug: XT-PIC timer in IOAPIC mode

"acpi_skip_timer_override" boot parameter
dmi_scan for common platforms, may be replaced with PCI-ID in future.
http://bugzilla.kernel.org/show_bug.cgi?id=1203

Documentation/kernel-parameters.txt

@@ -123,6 +123,10 @@ running once the system is up.
 
 	acpi_serialize	[HW,ACPI] force serialization of AML methods
 
+	acpi_skip_timer_override [HW,ACPI]
+			Recognize and ignore IRQ0/pin2 Interrupt Override.
+			For broken nForce2 BIOS resulting in XT-PIC timer.
+
 	ad1816=		[HW,OSS]
 			Format: <io>,<irq>,<dma>,<dma2>
 			See also Documentation/sound/oss/AD1816.

arch/i386/kernel/acpi/boot.c

@@ -68,6 +68,7 @@ int acpi_strict;
 
 acpi_interrupt_flags acpi_sci_flags __initdata;
 int acpi_sci_override_gsi __initdata;
+int acpi_skip_timer_override __initdata;
 
 #ifdef CONFIG_X86_LOCAL_APIC
 static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
@@ -335,6 +336,12 @@ acpi_parse_int_src_ovr (
 		return 0;
 	}
 
+	if (acpi_skip_timer_override &&
+		intsrc->bus_irq == 0 && intsrc->global_irq == 2) {
+			printk(PREFIX "BIOS IRQ0 pin2 override ignored.\n");
+			return 0;
+	}
+
 	mp_override_legacy_irq (
 		intsrc->bus_irq,
 		intsrc->flags.polarity,

arch/i386/kernel/dmi_scan.c

@@ -545,6 +545,19 @@ static __init int disable_acpi_pci(struct dmi_blacklist *d)
 }  
 #endif
 
+/*
+ * early nForce2 reference BIOS shipped with a
+ * bogus ACPI IRQ0 -> pin2 interrupt override -- ignore it
+ */
+static __init int ignore_timer_override(struct dmi_blacklist *d)
+{
+	extern int acpi_skip_timer_override;
+	printk(KERN_NOTICE "%s detected: BIOS IRQ0 pin2 override"
+		" will be ignored\n", d->ident); 	
+
+	acpi_skip_timer_override = 1;
+	return 0;
+}
 /*
  *	Process the DMI blacklists
  */
@@ -950,6 +963,49 @@ static __initdata struct dmi_blacklist dmi_blacklist[]={
 			MATCH(DMI_BOARD_VENDOR, "IBM"),
 			MATCH(DMI_PRODUCT_NAME, "eserver xSeries 440"),
 			NO_MATCH, NO_MATCH }},
+
+	/*
+	 * Systems with nForce2 BIOS timer override bug
+	 * nVidia claims all nForce have timer on pin0,
+	 * and applying this workaround is a NOP on fixed BIOS,
+	 * so prospects are good for replacing these entries
+	 * with something to key of chipset PCI-ID.
+	 */
+	{ ignore_timer_override, "Abit NF7-S v2", {
+			MATCH(DMI_BOARD_VENDOR, "http://www.abit.com.tw/"),
+			MATCH(DMI_BOARD_NAME, "NF7-S/NF7,NF7-V (nVidia-nForce2)"),
+			MATCH(DMI_BIOS_VERSION, "6.00 PG"),
+			MATCH(DMI_BIOS_DATE, "03/24/2004") }},
+
+	{ ignore_timer_override, "Asus A7N8X v2", {
+			MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
+			MATCH(DMI_BOARD_NAME, "A7N8X2.0"),
+			MATCH(DMI_BIOS_VERSION, "ASUS A7N8X2.0 Deluxe ACPI BIOS Rev 1007"),
+			MATCH(DMI_BIOS_DATE, "10/06/2003") }},
+
+	{ ignore_timer_override, "Asus A7N8X-X", {
+			MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
+			MATCH(DMI_BOARD_NAME, "A7N8X-X"),
+			MATCH(DMI_BIOS_VERSION, "ASUS A7N8X-X ACPI BIOS Rev 1009"),
+			MATCH(DMI_BIOS_DATE, "2/3/2004") }},
+
+	{ ignore_timer_override, "MSI K7N2-Delta", {
+			MATCH(DMI_BOARD_VENDOR, "MICRO-STAR INTERNATIONAL CO., LTD"),
+			MATCH(DMI_BOARD_NAME, "MS-6570"),
+			MATCH(DMI_BIOS_VERSION, "6.00 PG"),
+			MATCH(DMI_BIOS_DATE, "03/29/2004") }},
+
+	{ ignore_timer_override, "Shuttle SN41G2", {
+			MATCH(DMI_BOARD_VENDOR, "Shuttle Inc"),
+			MATCH(DMI_BOARD_NAME, "FN41"),
+			MATCH(DMI_BIOS_VERSION, "6.00 PG"),
+			MATCH(DMI_BIOS_DATE, "01/14/2004") }},
+
+	{ ignore_timer_override, "Shuttle AN35N", {
+			MATCH(DMI_BOARD_VENDOR, "Shuttle Inc"),
+			MATCH(DMI_BOARD_NAME, "AN35"),
+			MATCH(DMI_BIOS_VERSION, "6.00 PG"),
+			MATCH(DMI_BIOS_DATE, "12/05/2003") }},
 #endif	// CONFIG_ACPI_BOOT
 
 #ifdef	CONFIG_ACPI_PCI

arch/i386/kernel/setup.c

@@ -618,6 +618,9 @@ static void __init parse_cmdline_early (char ** cmdline_p)
 		else if (!memcmp(from, "acpi_sci=low", 12))
 			acpi_sci_flags.polarity = 3;
 
+		else if (!memcmp(from, "acpi_skip_timer_override", 24))
+			acpi_skip_timer_override = 1;
+
 #ifdef CONFIG_X86_LOCAL_APIC
 		/* disable IO-APIC */
 		else if (!memcmp(from, "noapic", 6))

include/asm-i386/acpi.h

@@ -125,6 +125,7 @@ extern int acpi_gsi_to_irq(u32 gsi, unsigned int *irq);
 #ifdef CONFIG_X86_IO_APIC
 extern int skip_ioapic_setup;
 extern int acpi_irq_to_vector(u32 irq);	/* deprecated in favor of acpi_gsi_to_irq */
+extern int acpi_skip_timer_override;
 
 static inline void disable_ioapic_setup(void)
 {