MIPS: Add hook to get C0 performance counter interrupt

The hardware perf event driver and oprofile interpret the global
cp0_perfcount_irq differently: in the hardware perf event driver
it is an offset from MIPS_CPU_IRQ_BASE and in oprofile it is the
actual IRQ number.  This still works most of the time since
MIPS_CPU_IRQ_BASE is usually 0, but is clearly wrong.  Since the
performance counter interrupt may vary from platform to platform
like the C0 timer interrupt, add the optional get_c0_perfcount_int
hook which returns the IRQ number of the performance counter.
The hook should return < 0 if the performance counter interrupt is
shared with the timer.  If the hook is not present, the CPU vector
reported in C0_IntCtl (cp0_perfcount_irq) is used.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Qais Yousef <qais.yousef@imgtec.com>
Tested-by: Qais Yousef <qais.yousef@imgtec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Jeffrey Deans <jeffrey.deans@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Jonas Gorski <jogo@openwrt.org>
Cc: John Crispin <blogic@openwrt.org>
Cc: David Daney <ddaney.cavm@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7805/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 14 insertions, 4 deletions

diff --git a/arch/mips/oprofile/op_model_mipsxx.c b/arch/mips/oprofile/op_model_mipsxx.c
index 42821ae..01f721a 100644
--- a/arch/mips/oprofile/op_model_mipsxx.c
+++ b/arch/mips/oprofile/op_model_mipsxx.c
@@ -11,6 +11,7 @@
 #include <linux/interrupt.h>
 #include <linux/smp.h>
 #include <asm/irq_regs.h>
+#include <asm/time.h>
 
 #include "op_impl.h"
 
@@ -35,6 +36,7 @@
 #define M_PERFCTL_COUNT_ALL_THREADS	(1UL	  << 13)
 
 static int (*save_perf_irq)(void);
+static int perfcount_irq;
 
 /*
  * XLR has only one set of counters per core. Designate the
@@ -431,8 +433,16 @@ 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,
+	if (get_c0_perfcount_int)
+		perfcount_irq = get_c0_perfcount_int();
+	else if ((cp0_perfcount_irq >= 0) &&
+		 (cp0_compare_irq != cp0_perfcount_irq))
+		perfcount_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
+	else
+		perfcount_irq = -1;
+
+	if (perfcount_irq >= 0)
+		return request_irq(perfcount_irq, mipsxx_perfcount_int,
 			0, "Perfcounter", save_perf_irq);
 
 	return 0;
@@ -442,8 +452,8 @@ 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);
+	if (perfcount_irq >= 0)
+		free_irq(perfcount_irq, save_perf_irq);
 
 	counters = counters_per_cpu_to_total(counters);
 	on_each_cpu(reset_counters, (void *)(long)counters, 1);