MIPS: make oprofile use cp0_perfcount_irq if it is set

Make the oprofile code use the performance counters irq.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3723/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/perf_event_mipsxx.c

@@ -1532,7 +1532,8 @@ init_hw_perf_events(void)
 		irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
 	} else {
 #endif
-		if (cp0_perfcount_irq >= 0)
+		if ((cp0_perfcount_irq >= 0) &&
+				(cp0_compare_irq != cp0_perfcount_irq))
 			irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
 		else
 			irq = -1;

arch/mips/oprofile/op_model_mipsxx.c

@@ -298,6 +298,11 @@ static void reset_counters(void *arg)
 	}
 }
 
+static irqreturn_t mipsxx_perfcount_int(int irq, void *dev_id)
+{
+	return mipsxx_perfcount_handler();
+}
+
 static int __init mipsxx_init(void)
 {
 	int counters;
@@ -374,6 +379,10 @@ static int __init mipsxx_init(void)
 	save_perf_irq = perf_irq;
 	perf_irq = mipsxx_perfcount_handler;
 
+	if ((cp0_perfcount_irq >= 0) && (cp0_compare_irq != cp0_perfcount_irq))
+		return request_irq(cp0_perfcount_irq, mipsxx_perfcount_int,
+			0, "Perfcounter", save_perf_irq);
+
 	return 0;
 }
 
@@ -381,6 +390,9 @@ static void mipsxx_exit(void)
 {
 	int counters = op_model_mipsxx_ops.num_counters;
 
+	if ((cp0_perfcount_irq >= 0) && (cp0_compare_irq != cp0_perfcount_irq))
+		free_irq(cp0_perfcount_irq, save_perf_irq);
+
 	counters = counters_per_cpu_to_total(counters);
 	on_each_cpu(reset_counters, (void *)(long)counters, 1);