5 files changed, 83 insertions, 9 deletions

diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 9c5fc15d03d1..654ea4fccff8 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -40,6 +40,13 @@ APICs
    no_timer_check Don't check the IO-APIC timer. This can work around
                  problems with incorrect timer initialization on some boards.
 
+   apicmaintimer Run time keeping from the local APIC timer instead
+                 of using the PIT/HPET interrupt for this. This is useful
+                 when the PIT/HPET interrupts are unreliable.
+
+   noapicmaintimer  Don't do time keeping using the APIC timer.
+                 Useful when this option was auto selected, but doesn't work.
+
 Early Console
 
    syntax: earlyprintk=vga
diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index 5d3c5b07b8db..14751dda7dcf 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -35,8 +35,11 @@
 #include <asm/mach_apic.h>
 #include <asm/nmi.h>
 #include <asm/idle.h>
+#include <asm/proto.h>
+#include <asm/timex.h>
 
 int apic_verbosity;
+int apic_runs_main_timer;
 
 int disable_apic_timer __initdata;
 
@@ -702,9 +705,17 @@ static void setup_APIC_timer(unsigned int clocks)
                         c2 |= inb_p(0x40) << 8;
                 } while (c2 - c1 < 300);
         }
-
         __setup_APIC_LVTT(clocks);
-
+        /* Turn off PIT interrupt if we use APIC timer as main timer.
+           Only works with the PM timer right now
+           TBD fix it for HPET too. */
+        if (vxtime.mode == VXTIME_PMTMR &&
+                smp_processor_id() == boot_cpu_id &&
+                apic_runs_main_timer == 1 &&
+                !cpu_isset(boot_cpu_id, timer_interrupt_broadcast_ipi_mask)) {
+                stop_timer_interrupt();
+                apic_runs_main_timer++;
+        }
         local_irq_restore(flags);
 }
 
@@ -872,6 +883,8 @@ void smp_local_timer_interrupt(struct pt_regs *regs)
 #ifdef CONFIG_SMP
         update_process_times(user_mode(regs));
 #endif
+        if (apic_runs_main_timer > 1 && smp_processor_id() == boot_cpu_id)
+                main_timer_handler(regs);
         /*
          * We take the 'long' return path, and there every subsystem
          * grabs the appropriate locks (kernel lock/ irq lock).
@@ -1081,10 +1094,27 @@ static __init int setup_nolapic(char *str)
 
 static __init int setup_noapictimer(char *str) 
 { 
+        if (str[0] != ' ' && str[0] != 0)
+                return -1;
         disable_apic_timer = 1;
         return 0;
 } 
 
+static __init int setup_apicmaintimer(char *str)
+{
+        apic_runs_main_timer = 1;
+        nohpet = 1;
+        return 0;
+}
+__setup("apicmaintimer", setup_apicmaintimer);
+
+static __init int setup_noapicmaintimer(char *str)
+{
+        apic_runs_main_timer = -1;
+        return 0;
+}
+__setup("noapicmaintimer", setup_noapicmaintimer);
+
 /* dummy parsing: see setup.c */
 
 __setup("disableapic", setup_disableapic); 
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index f8c47c688443..91a448a86ebd 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -51,7 +51,7 @@ extern int using_apic_timer;
 DEFINE_SPINLOCK(rtc_lock);
 DEFINE_SPINLOCK(i8253_lock);
 
-static int nohpet __initdata = 0;
+int nohpet __initdata = 0;
 static int notsc __initdata = 0;
 
 #undef HPET_HACK_ENABLE_DANGEROUS
@@ -345,7 +345,7 @@ static noinline void handle_lost_ticks(int lost, struct pt_regs *regs)
 #endif
 }
 
-static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+void main_timer_handler(struct pt_regs *regs)
 {
         static unsigned long rtc_update = 0;
         unsigned long tsc;
@@ -458,12 +458,17 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
         }
  
         write_sequnlock(&xtime_lock);
+}
 
+static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+        if (apic_runs_main_timer > 1)
+                return IRQ_HANDLED;
+        main_timer_handler(regs);
 #ifdef CONFIG_X86_LOCAL_APIC
         if (using_apic_timer)
                 smp_send_timer_broadcast_ipi();
 #endif
-
         return IRQ_HANDLED;
 }
 
@@ -843,17 +848,43 @@ static int hpet_reenable(void)
         return hpet_timer_stop_set_go(hpet_tick);
 }
 
-void __init pit_init(void)
+#define PIT_MODE 0x43
+#define PIT_CH0  0x40
+
+static void __init __pit_init(int val, u8 mode)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&i8253_lock, flags);
-        outb_p(0x34, 0x43);             /* binary, mode 2, LSB/MSB, ch 0 */
-        outb_p(LATCH & 0xff, 0x40);     /* LSB */
-        outb_p(LATCH >> 8, 0x40);       /* MSB */
+        outb_p(mode, PIT_MODE);
+        outb_p(val & 0xff, PIT_CH0);    /* LSB */
+        outb_p(val >> 8, PIT_CH0);      /* MSB */
         spin_unlock_irqrestore(&i8253_lock, flags);
 }
 
+void __init pit_init(void)
+{
+        __pit_init(LATCH, 0x34); /* binary, mode 2, LSB/MSB, ch 0 */
+}
+
+void __init pit_stop_interrupt(void)
+{
+        __pit_init(0, 0x30); /* mode 0 */
+}
+
+void __init stop_timer_interrupt(void)
+{
+        char *name;
+        if (vxtime.hpet_address) {
+                name = "HPET";
+                hpet_timer_stop_set_go(0);
+        } else {
+                name = "PIT";
+                pit_stop_interrupt();
+        }
+        printk(KERN_INFO "timer: %s interrupt stopped.\n", name);
+}
+
 int __init time_setup(char *str)
 {
         report_lost_ticks = 1;
diff --git a/include/asm-x86_64/apic.h b/include/asm-x86_64/apic.h
index 4f6a4dc455bb..bdbd8935612a 100644
--- a/include/asm-x86_64/apic.h
+++ b/include/asm-x86_64/apic.h
@@ -17,6 +17,7 @@
 #define APIC_DEBUG   2
 
 extern int apic_verbosity;
+extern int apic_runs_main_timer;
 
 /*
  * Define the default level of output to be very little
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index d35c7e06f340..c1e2307445d4 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -49,6 +49,8 @@ extern u32 pmtmr_ioport;
 #endif
 extern unsigned long long monotonic_base;
 extern int sysctl_vsyscall;
+extern int nohpet;
+extern unsigned long vxtime_hz;
 
 extern void do_softirq_thunk(void);
 
@@ -69,6 +71,9 @@ extern void free_bootmem_generic(unsigned long phys, unsigned len);
 
 extern void load_gs_index(unsigned gs);
 
+extern void stop_timer_interrupt(void);
+extern void main_timer_handler(struct pt_regs *regs);
+
 extern unsigned long end_pfn_map; 
 
 extern void show_trace(unsigned long * rsp);