[PATCH] x86-64: Try multiple timer variants in check_timer

Instead of adding all kinds of more quirks try various timer
routing variants in check_timer.

In particular this tries to handle quirks from:
- Nvidia NF2-4 reference BIOS: wrong timer override
- Asus: Wrong timer override but no HPET table
- ATI: require timer disabled in 8259
- Some boards: require timer enabled in 8259

We just try many of the the known variants in the hopefully right order
in check_timer.

Trying pin 0/2 on Nvidia suggested by Tim Hockin.

TBD Experimental. Needs a lot of testing
Signed-off-by: Andi Kleen <ak@suse.de>

Documentation/x86_64/boot-options.txt

@@ -52,10 +52,6 @@ APICs
 		 apicmaintimer. Useful when your PIT timer is totally
 		 broken.
 
-   disable_8254_timer / enable_8254_timer
-		 Enable interrupt 0 timer routing over the 8254 in addition to over
-	         the IO-APIC. The kernel tries to set a sensible default.
-
 Early Console
 
    syntax: earlyprintk=vga

arch/x86_64/kernel/early-quirks.c

@@ -69,11 +69,6 @@ static void nvidia_bugs(void)
 
 static void ati_bugs(void)
 {
-	if (timer_over_8254 == 1) {
-		timer_over_8254 = 0;
-		printk(KERN_INFO
-	 	"ATI board detected. Disabling timer routing over 8254.\n");
-	}
 }
 
 struct chipset {

arch/x86_64/kernel/io_apic.c

@@ -55,10 +55,6 @@ int sis_apic_bug; /* not actually supported, dummy for compile */
 
 static int no_timer_check;
 
-static int disable_timer_pin_1 __initdata;
-
-int timer_over_8254 __initdata = 1;
-
 /* Where if anywhere is the i8259 connect in external int mode */
 static struct { int pin, apic; } ioapic_i8259 = { -1, -1 };
 
@@ -348,29 +344,6 @@ static int __init disable_ioapic_setup(char *str)
 }
 early_param("noapic", disable_ioapic_setup);
 
-/* Actually the next is obsolete, but keep it for paranoid reasons -AK */
-static int __init disable_timer_pin_setup(char *arg)
-{
-	disable_timer_pin_1 = 1;
-	return 1;
-}
-__setup("disable_timer_pin_1", disable_timer_pin_setup);
-
-static int __init setup_disable_8254_timer(char *s)
-{
-	timer_over_8254 = -1;
-	return 1;
-}
-static int __init setup_enable_8254_timer(char *s)
-{
-	timer_over_8254 = 2;
-	return 1;
-}
-
-__setup("disable_8254_timer", setup_disable_8254_timer);
-__setup("enable_8254_timer", setup_enable_8254_timer);
-
-
 /*
  * Find the IRQ entry number of a certain pin.
  */
@@ -1579,10 +1552,33 @@ static inline void unlock_ExtINT_logic(void)
  * a wide range of boards and BIOS bugs.  Fortunately only the timer IRQ
  * is so screwy.  Thanks to Brian Perkins for testing/hacking this beast
  * fanatically on his truly buggy board.
- *
- * FIXME: really need to revamp this for modern platforms only.
  */
-static inline void check_timer(void)
+
+static int try_apic_pin(int apic, int pin, char *msg)
+{
+	apic_printk(APIC_VERBOSE, KERN_INFO
+		    "..TIMER: trying IO-APIC=%d PIN=%d %s",
+		    apic, pin, msg);
+
+	/*
+	 * Ok, does IRQ0 through the IOAPIC work?
+	 */
+	if (!no_timer_check && timer_irq_works()) {
+		nmi_watchdog_default();
+		if (nmi_watchdog == NMI_IO_APIC) {
+			disable_8259A_irq(0);
+			setup_nmi();
+			enable_8259A_irq(0);
+		}
+		return 1;
+	}
+	clear_IO_APIC_pin(apic, pin);
+	apic_printk(APIC_QUIET, KERN_ERR " .. failed\n");
+	return 0;
+}
+
+/* The function from hell */
+static void check_timer(void)
 {
 	int apic1, pin1, apic2, pin2;
 	int vector;
@@ -1603,61 +1599,43 @@ static inline void check_timer(void)
 	 */
 	apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
-	if (timer_over_8254 > 0)
-		enable_8259A_irq(0);
 
 	pin1  = find_isa_irq_pin(0, mp_INT);
 	apic1 = find_isa_irq_apic(0, mp_INT);
 	pin2  = ioapic_i8259.pin;
 	apic2 = ioapic_i8259.apic;
 
-	apic_printk(APIC_VERBOSE,KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
-		vector, apic1, pin1, apic2, pin2);
+	/* Do this first, otherwise we get double interrupts on ATI boards */
+	if ((pin1 != -1) && try_apic_pin(apic1, pin1,"with 8259 IRQ0 disabled"))
+		return;
 
-	if (pin1 != -1) {
-		/*
-		 * Ok, does IRQ0 through the IOAPIC work?
-		 */
+	/* Now try again with IRQ0 8259A enabled.
+	   Assumes timer is on IO-APIC 0 ?!? */
+	enable_8259A_irq(0);
 	unmask_IO_APIC_irq(0);
-		if (!no_timer_check && timer_irq_works()) {
-			nmi_watchdog_default();
-			if (nmi_watchdog == NMI_IO_APIC) {
+	if (try_apic_pin(apic1, pin1, "with 8259 IRQ0 enabled"))
+		return;
 	disable_8259A_irq(0);
-				setup_nmi();
-				enable_8259A_irq(0);
-			}
-			if (disable_timer_pin_1 > 0)
-				clear_IO_APIC_pin(0, pin1);
+
+	/* Always try pin0 and pin2 on APIC 0 to handle buggy timer overrides
+	   on Nvidia boards */
+	if (!(apic1 == 0 && pin1 == 0) &&
+	    try_apic_pin(0, 0, "fallback with 8259 IRQ0 disabled"))
+		return;
+	if (!(apic1 == 0 && pin1 == 2) &&
+	    try_apic_pin(0, 2, "fallback with 8259 IRQ0 disabled"))
 		return;
-		}
-		clear_IO_APIC_pin(apic1, pin1);
-		apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: 8254 timer not "
-				"connected to IO-APIC\n");
-	}
 
-	apic_printk(APIC_VERBOSE,KERN_INFO "...trying to set up timer (IRQ0) "
-				"through the 8259A ... ");
+	/* Then try pure 8259A routing on the 8259 as reported by BIOS*/
+	enable_8259A_irq(0);
 	if (pin2 != -1) {
-		apic_printk(APIC_VERBOSE,"\n..... (found apic %d pin %d) ...",
-			apic2, pin2);
-		/*
-		 * legacy devices should be connected to IO APIC #0
-		 */
 		setup_ExtINT_IRQ0_pin(apic2, pin2, vector);
-		if (timer_irq_works()) {
-			apic_printk(APIC_VERBOSE," works.\n");
-			nmi_watchdog_default();
-			if (nmi_watchdog == NMI_IO_APIC) {
-				setup_nmi();
-			}
+		if (try_apic_pin(apic2,pin2,"8259A broadcast ExtINT from BIOS"))
 			return;
 	}
-		/*
-		 * Cleanup, just in case ...
-		 */
-		clear_IO_APIC_pin(apic2, pin2);
-	}
-	apic_printk(APIC_VERBOSE," failed.\n");
+
+	/* Tried all possibilities to go through the IO-APIC. Now come the
+	   really cheesy fallbacks. */
 
 	if (nmi_watchdog == NMI_IO_APIC) {
 		printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");