alpha: implement HW performance events on the EV67 and later CPUs

This implements hardware performance events for the EV67 and later CPUs
within the Linux performance events subsystem.  Only using the performance
monitoring unit in HP/Compaq's so called "Aggregrate mode" is supported.

The code has been implemented in a manner that makes extension to other
older Alpha CPUs relatively straightforward should some mug wish to
indulge themselves.
Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jay Estabrook <jay.estabrook@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/include/asm/perf_event.h

@@ -2,8 +2,14 @@
 #define __ASM_ALPHA_PERF_EVENT_H
 
 /* Alpha only supports software events through this interface. */
-static inline void set_perf_event_pending(void) { }
+extern void set_perf_event_pending(void);
 
 #define PERF_EVENT_INDEX_OFFSET 0
 
+#ifdef CONFIG_PERF_EVENTS
+extern void init_hw_perf_events(void);
+#else
+static inline void init_hw_perf_events(void)    { }
+#endif
+
 #endif /* __ASM_ALPHA_PERF_EVENT_H */

arch/alpha/kernel/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_SMP)	+= smp.o
 obj-$(CONFIG_PCI)	+= pci.o pci_iommu.o pci-sysfs.o
 obj-$(CONFIG_SRM_ENV)	+= srm_env.o
 obj-$(CONFIG_MODULES)	+= module.o
+obj-$(CONFIG_PERF_EVENTS) += perf_event.o
 
 ifdef CONFIG_ALPHA_GENERIC
 

arch/alpha/kernel/irq_alpha.c

@@ -10,6 +10,7 @@
 
 #include <asm/machvec.h>
 #include <asm/dma.h>
+#include <asm/perf_event.h>
 
 #include "proto.h"
 #include "irq_impl.h"
@@ -111,6 +112,8 @@ init_IRQ(void)
 	wrent(entInt, 0);
 
 	alpha_mv.init_irq();
+
+	init_hw_perf_events();
 }
 
 /*

arch/alpha/kernel/time.c

@@ -41,6 +41,7 @@
 #include <linux/init.h>
 #include <linux/bcd.h>
 #include <linux/profile.h>
+#include <linux/perf_event.h>
 
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -82,6 +83,26 @@ static struct {
 
 unsigned long est_cycle_freq;
 
+#ifdef CONFIG_PERF_EVENTS
+
+DEFINE_PER_CPU(u8, perf_event_pending);
+
+#define set_perf_event_pending_flag()  __get_cpu_var(perf_event_pending) = 1
+#define test_perf_event_pending()      __get_cpu_var(perf_event_pending)
+#define clear_perf_event_pending()     __get_cpu_var(perf_event_pending) = 0
+
+void set_perf_event_pending(void)
+{
+	set_perf_event_pending_flag();
+}
+
+#else  /* CONFIG_PERF_EVENTS */
+
+#define test_perf_event_pending()      0
+#define clear_perf_event_pending()
+
+#endif /* CONFIG_PERF_EVENTS */
+
 
 static inline __u32 rpcc(void)
 {
@@ -175,6 +196,11 @@ irqreturn_t timer_interrupt(int irq, void *dev)
 		update_process_times(user_mode(get_irq_regs()));
 #endif
 
+	if (test_perf_event_pending()) {
+		clear_perf_event_pending();
+		perf_event_do_pending();
+	}
+
 	return IRQ_HANDLED;
 }