[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",
 };