x86: SB450: skip IRQ0 override if it is not routed to INT2 of IOAPIC

On some HP nx6... laptops (e.g. nx6325) BIOS reports an IRQ0 override
but the SB450 chipset is configured such that timer interrupts goe to
INT0 of IOAPIC.

Check IRQ0 routing and if it is routed to INT0 of IOAPIC skip the
timer override.

[ This more generic PCI ID based quirk should alleviate the need for
  dmi_ignore_irq0_timer_override DMI quirks. ]
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: "Maciej W. Rozycki" <macro@linux-mips.org>
Tested-by: Dmitry Torokhov <dtor@mail.ru>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/early-quirks.c

@@ -95,6 +95,52 @@ static void __init nvidia_bugs(int num, int slot, int func)
 
 }
 
+static u32 ati_ixp4x0_rev(int num, int slot, int func)
+{
+	u32 d;
+	u8  b;
+
+	b = read_pci_config_byte(num, slot, func, 0xac);
+	b &= ~(1<<5);
+	write_pci_config_byte(num, slot, func, 0xac, b);
+
+	d = read_pci_config(num, slot, func, 0x70);
+	d |= 1<<8;
+	write_pci_config(num, slot, func, 0x70, d);
+
+	d = read_pci_config(num, slot, func, 0x8);
+	d &= 0xff;
+	return d;
+}
+
+static void __init ati_bugs(int num, int slot, int func)
+{
+#if defined(CONFIG_ACPI) && defined (CONFIG_X86_IO_APIC)
+	u32 d;
+	u8  b;
+
+	if (acpi_use_timer_override)
+		return;
+
+	d = ati_ixp4x0_rev(num, slot, func);
+	if (d  < 0x82)
+		acpi_skip_timer_override = 1;
+	else {
+		/* check for IRQ0 interrupt swap */
+		outb(0x72, 0xcd6); b = inb(0xcd7);
+		if (!(b & 0x2))
+			acpi_skip_timer_override = 1;
+	}
+
+	if (acpi_skip_timer_override) {
+		printk(KERN_INFO "SB4X0 revision 0x%x\n", d);
+		printk(KERN_INFO "Ignoring ACPI timer override.\n");
+		printk(KERN_INFO "If you got timer trouble "
+		       "try acpi_use_timer_override\n");
+	}
+#endif
+}
+
 #define QFLAG_APPLY_ONCE 	0x1
 #define QFLAG_APPLIED		0x2
 #define QFLAG_DONE		(QFLAG_APPLY_ONCE|QFLAG_APPLIED)
@@ -114,6 +160,8 @@ static struct chipset early_qrk[] __initdata = {
 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
 	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
 	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
+	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS,
+	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
 	{}
 };