[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>

2 files changed, 37 insertions, 19 deletions

diff --git a/arch/mips/kernel/smp-mt.c b/arch/mips/kernel/smp-mt.c
index 64b62bdfb4f6..b8fa7ddd78f6 100644
--- a/arch/mips/kernel/smp-mt.c
+++ b/arch/mips/kernel/smp-mt.c
@@ -129,13 +129,13 @@ static irqreturn_t ipi_call_interrupt(int irq, void *dev_id)
 
 static struct irqaction irq_resched = {
 	.handler	= ipi_resched_interrupt,
-	.flags		= IRQF_DISABLED,
+	.flags		= IRQF_DISABLED|IRQF_PERCPU,
 	.name		= "IPI_resched"
 };
 
 static struct irqaction irq_call = {
 	.handler	= ipi_call_interrupt,
-	.flags		= IRQF_DISABLED,
+	.flags		= IRQF_DISABLED|IRQF_PERCPU,
 	.name		= "IPI_call"
 };
 
@@ -275,10 +275,7 @@ void __init plat_prepare_cpus(unsigned int max_cpus)
 	setup_irq(cpu_ipi_resched_irq, &irq_resched);
 	setup_irq(cpu_ipi_call_irq, &irq_call);
 
-	/* need to mark IPI's as IRQ_PER_CPU */
-	irq_desc[cpu_ipi_resched_irq].status |= IRQ_PER_CPU;
 	set_irq_handler(cpu_ipi_resched_irq, handle_percpu_irq);
-	irq_desc[cpu_ipi_call_irq].status |= IRQ_PER_CPU;
 	set_irq_handler(cpu_ipi_call_irq, handle_percpu_irq);
 }
 
@@ -326,8 +323,11 @@ void prom_boot_secondary(int cpu, struct task_struct *idle)
 
 void prom_init_secondary(void)
 {
+	/* Enable per-cpu interrupts */
+
+	/* This is Malta specific: IPI,performance and timer inetrrupts */
 	write_c0_status((read_c0_status() & ~ST0_IM ) |
-	                (STATUSF_IP0 | STATUSF_IP1 | STATUSF_IP7));
+	                (STATUSF_IP0 | STATUSF_IP1 | STATUSF_IP6 | STATUSF_IP7));
 }
 
 void prom_smp_finish(void)
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",
 };