[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 <[e-mail]>
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/kernel/smp-mt.c

···
 
 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"
 };
 
···
 	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);
 }
 
···
 
 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)

arch/mips/kernel/time.c

···
 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;
···
 	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();
···
 
 static struct irqaction timer_irqaction = {
 	.handler = timer_interrupt,
-	.flags = IRQF_DISABLED,
+	.flags = IRQF_DISABLED | IRQF_PERCPU,
 	.name = "timer",
 };
 

arch/mips/mips-boards/generic/time.c

···
 
 unsigned long cpu_khz;
 
-#define CPUCTR_IMASKBIT (0x100 << MIPSCPU_INT_CPUCTR)
-
 static int mips_cpu_timer_irq;
+extern int mipsxx_perfcount_irq;
 extern void smtc_timer_broadcast(int);
 
 static void mips_timer_dispatch(void)
 {
 	do_IRQ(mips_cpu_timer_irq);
+}
+
+static void mips_perf_dispatch(void)
+{
+	do_IRQ(mipsxx_perfcount_irq);
 }
 
 /*
···
 extern int null_perf_irq(void);
 
 extern int (*perf_irq)(void);
+
+/*
+ * 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;
+}
 
 irqreturn_t mips_timer_interrupt(int irq, void *dev_id)
 {
···
 	 * We could be here due to timer interrupt,
 	 * perf counter overflow, or both.
 	 */
-	if (read_c0_cause() & (1 << 26))
-		perf_irq();
+	(void) handle_perf_irq(1);
 
 	if (read_c0_cause() & (1 << 30)) {
 		/*
···
 #else /* CONFIG_MIPS_MT_SMTC */
 	int r2 = cpu_has_mips_r2;
 
+	if (handle_perf_irq(r2))
+		goto out;
+
+	if (r2 && ((read_c0_cause() & (1 << 30)) == 0))
+		goto out;
+
 	if (cpu == 0) {
 		/*
 		 * CPU 0 handles the global timer interrupt job and process
 		 * accounting resets count/compare registers to trigger next
 		 * timer int.
 		 */
-		if (!r2 || (read_c0_cause() & (1 << 26)))
-			if (perf_irq())
-				goto out;
-
-		/* we keep interrupt disabled all the time */
-		if (!r2 || (read_c0_cause() & (1 << 30)))
-			timer_interrupt(irq, NULL);
+		timer_interrupt(irq, NULL);
 	} else {
 		/* Everyone else needs to reset the timer int here as
 		   ll_local_timer_interrupt doesn't */
···
 	mips_scroll_message();
 }
 
+irqreturn_t mips_perf_interrupt(int irq, void *dev_id)
+{
+	return perf_irq();
+}
+
+static struct irqaction perf_irqaction = {
+	.handler = mips_perf_interrupt,
+	.flags = IRQF_DISABLED | IRQF_PERCPU,
+	.name = "performance",
+};
+
+void __init plat_perf_setup(struct irqaction *irq)
+{
+	int hwint = 0;
+	mipsxx_perfcount_irq = -1;
+
+#ifdef MSC01E_INT_BASE
+	if (cpu_has_veic) {
+		set_vi_handler (MSC01E_INT_PERFCTR, mips_perf_dispatch);
+		mipsxx_perfcount_irq = MSC01E_INT_BASE + MSC01E_INT_PERFCTR;
+	} else
+#endif
+	if (cpu_has_mips_r2) {
+		/*
+		 * Read IntCtl.IPPCI to determine the performance
+		 * counter interrupt
+		 */
+		hwint = (read_c0_intctl () >> 26) & 7;
+		if (hwint != MIPSCPU_INT_CPUCTR) {
+			if (cpu_has_vint)
+				set_vi_handler (hwint, mips_perf_dispatch);
+			mipsxx_perfcount_irq = MIPSCPU_INT_BASE + hwint;
+		}
+	}
+	if (mipsxx_perfcount_irq >= 0) {
+#ifdef CONFIG_MIPS_MT_SMTC
+		setup_irq_smtc(mipsxx_perfcount_irq, irq, 0x100 << hwint);
+#else
+		setup_irq(mipsxx_perfcount_irq, irq);
+#endif /* CONFIG_MIPS_MT_SMTC */
+#ifdef CONFIG_SMP
+		set_irq_handler(mipsxx_perfcount_irq, handle_percpu_irq);
+#endif
+	}
+}
+
 void __init plat_timer_setup(struct irqaction *irq)
 {
-#ifdef MSC01E_INT_BASE
+	int hwint = 0;
 	if (cpu_has_veic) {
 		set_vi_handler (MSC01E_INT_CPUCTR, mips_timer_dispatch);
 		mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
-	} else
-#endif
-	{
-		if (cpu_has_vint)
-			set_vi_handler (MIPSCPU_INT_CPUCTR, mips_timer_dispatch);
-		mips_cpu_timer_irq = MIPSCPU_INT_BASE + MIPSCPU_INT_CPUCTR;
 	}
-
+	else {
+		if (cpu_has_mips_r2)
+			/*
+			 * Read IntCtl.IPTI to determine the timer interrupt
+			 */
+			hwint = (read_c0_intctl () >> 29) & 7;
+		else
+			hwint = MIPSCPU_INT_CPUCTR;
+		if (cpu_has_vint)
+			set_vi_handler (hwint, mips_timer_dispatch);
+		mips_cpu_timer_irq = MIPSCPU_INT_BASE + hwint;
+	}
 
 	/* we are using the cpu counter for timer interrupts */
 	irq->handler = mips_timer_interrupt;	/* we use our own handler */
 #ifdef CONFIG_MIPS_MT_SMTC
-	setup_irq_smtc(mips_cpu_timer_irq, irq, CPUCTR_IMASKBIT);
+	setup_irq_smtc(mips_cpu_timer_irq, irq, 0x100 << hwint);
 #else
 	setup_irq(mips_cpu_timer_irq, irq);
 #endif /* CONFIG_MIPS_MT_SMTC */
-
 #ifdef CONFIG_SMP
-	/* irq_desc(riptor) is a global resource, when the interrupt overlaps
-	   on seperate cpu's the first one tries to handle the second interrupt.
-	   The effect is that the int remains disabled on the second cpu.
-	   Mark the interrupt with IRQ_PER_CPU to avoid any confusion */
-	irq_desc[mips_cpu_timer_irq].status |= IRQ_PER_CPU;
 	set_irq_handler(mips_cpu_timer_irq, handle_percpu_irq);
 #endif
+
+	plat_perf_setup(&perf_irqaction);
 }

arch/mips/oprofile/op_model_mipsxx.c

···
 	unsigned int counters = op_model_mipsxx_ops.num_counters;
 	unsigned int control;
 	unsigned int counter;
-	int handled = 0;
+	int handled = IRQ_NONE;
+
+	if (cpu_has_mips_r2 && !(read_c0_cause() & (1 << 26)))
+		return handled;
 
 	switch (counters) {
 #define HANDLE_COUNTER(n)						\
···
 		    (counter & M_COUNTER_OVERFLOW)) {			\
 			oprofile_add_sample(get_irq_regs(), n);		\
 			w_c0_perfcntr ## n(reg.counter[n]);		\
-			handled = 1;					\
+			handled = IRQ_HANDLED;				\
 		}
 	HANDLE_COUNTER(3)
 	HANDLE_COUNTER(2)