[MIPS] Separate performance counter interrupts

Support for performance counter overflow interrupt that is on a separate
interrupt from the timer.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 31 insertions, 13 deletions

diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index 751b4a18b133..7def1ff3da94 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -199,6 +199,30 @@ int (*perf_irq)(void) = null_perf_irq;
 EXPORT_SYMBOL(null_perf_irq);
 EXPORT_SYMBOL(perf_irq);
 
+/*
+ * Performance counter IRQ or -1 if shared with timer
+ */
+int mipsxx_perfcount_irq;
+EXPORT_SYMBOL(mipsxx_perfcount_irq);
+
+/*
+ * Possibly handle a performance counter interrupt.
+ * Return true if the timer interrupt should not be checked
+ */
+static inline int handle_perf_irq (int r2)
+{
+        /*
+         * The performance counter overflow interrupt may be shared with the
+         * timer interrupt (mipsxx_perfcount_irq < 0). If it is and a
+         * performance counter has overflowed (perf_irq() == IRQ_HANDLED)
+         * and we can't reliably determine if a counter interrupt has also
+         * happened (!r2) then don't check for a timer interrupt.
+         */
+        return (mipsxx_perfcount_irq < 0) &&
+                perf_irq() == IRQ_HANDLED &&
+                !r2;
+}
+
 asmlinkage void ll_timer_interrupt(int irq)
 {
         int r2 = cpu_has_mips_r2;
@@ -206,19 +230,13 @@ asmlinkage void ll_timer_interrupt(int irq)
         irq_enter();
         kstat_this_cpu.irqs[irq]++;
 
-        /*
-         * Suckage alert:
-         * Before R2 of the architecture there was no way to see if a
-         * performance counter interrupt was pending, so we have to run the
-         * performance counter interrupt handler anyway.
-         */
-        if (!r2 || (read_c0_cause() & (1 << 26)))
-                if (perf_irq())
-                        goto out;
+        if (handle_perf_irq(r2))
+                goto out;
 
-        /* we keep interrupt disabled all the time */
-        if (!r2 || (read_c0_cause() & (1 << 30)))
-                timer_interrupt(irq, NULL);
+        if (r2 && ((read_c0_cause() & (1 << 30)) == 0))
+                goto out;
+
+        timer_interrupt(irq, NULL);
 
 out:
         irq_exit();
@@ -258,7 +276,7 @@ unsigned int mips_hpt_frequency;
 
 static struct irqaction timer_irqaction = {
         .handler = timer_interrupt,
-        .flags = IRQF_DISABLED,
+        .flags = IRQF_DISABLED | IRQF_PERCPU,
         .name = "timer",
 };