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authorJamie Iles <jamie.iles@picochip.com>2010-02-02 20:23:15 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-02-12 17:23:43 +0000
commit0f4f0672ac950c96cffaf84a666d35e817d7c3ca (patch)
treecb4c1ec72f7842622c636a76f5ca519f3f3e8ea8
parent74d2e4f8d79ae0c4b6ec027958d5b18058662eea (diff)
ARM: 5899/2: arm: provide a mechanism to reserve performance counters
To add support for perf events and to allow the hardware counters to be shared with oprofile, we need a way to reserve access to the pmu (performance monitor unit). Platforms with PMU interrupts should register the interrupts in arch/arm/kernel/pmu.c Signed-off-by: Jamie Iles <jamie.iles@picochip.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/Kconfig5
-rw-r--r--arch/arm/include/asm/pmu.h75
-rw-r--r--arch/arm/kernel/Makefile1
-rw-r--r--arch/arm/kernel/pmu.c103
4 files changed, 184 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 233a222752c..9e08891062b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -863,6 +863,11 @@ config XSCALE_PMU
depends on CPU_XSCALE && !XSCALE_PMU_TIMER
default y
+config CPU_HAS_PMU
+ depends on CPU_V6 || CPU_V7 || XSCALE_PMU
+ default y
+ bool
+
if !MMU
source "arch/arm/Kconfig-nommu"
endif
diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
new file mode 100644
index 00000000000..2829b9f981a
--- /dev/null
+++ b/arch/arm/include/asm/pmu.h
@@ -0,0 +1,75 @@
+/*
+ * linux/arch/arm/include/asm/pmu.h
+ *
+ * Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __ARM_PMU_H__
+#define __ARM_PMU_H__
+
+#ifdef CONFIG_CPU_HAS_PMU
+
+struct pmu_irqs {
+ const int *irqs;
+ int num_irqs;
+};
+
+/**
+ * reserve_pmu() - reserve the hardware performance counters
+ *
+ * Reserve the hardware performance counters in the system for exclusive use.
+ * The 'struct pmu_irqs' for the system is returned on success, ERR_PTR()
+ * encoded error on failure.
+ */
+extern const struct pmu_irqs *
+reserve_pmu(void);
+
+/**
+ * release_pmu() - Relinquish control of the performance counters
+ *
+ * Release the performance counters and allow someone else to use them.
+ * Callers must have disabled the counters and released IRQs before calling
+ * this. The 'struct pmu_irqs' returned from reserve_pmu() must be passed as
+ * a cookie.
+ */
+extern int
+release_pmu(const struct pmu_irqs *irqs);
+
+/**
+ * init_pmu() - Initialise the PMU.
+ *
+ * Initialise the system ready for PMU enabling. This should typically set the
+ * IRQ affinity and nothing else. The users (oprofile/perf events etc) will do
+ * the actual hardware initialisation.
+ */
+extern int
+init_pmu(void);
+
+#else /* CONFIG_CPU_HAS_PMU */
+
+static inline const struct pmu_irqs *
+reserve_pmu(void)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline int
+release_pmu(const struct pmu_irqs *irqs)
+{
+ return -ENODEV;
+}
+
+static inline int
+init_pmu(void)
+{
+ return -ENODEV;
+}
+
+#endif /* CONFIG_CPU_HAS_PMU */
+
+#endif /* __ARM_PMU_H__ */
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index dd00f747e2a..216890d804c 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_CPU_XSCALE) += xscale-cp0.o
obj-$(CONFIG_CPU_XSC3) += xscale-cp0.o
obj-$(CONFIG_CPU_MOHAWK) += xscale-cp0.o
obj-$(CONFIG_IWMMXT) += iwmmxt.o
+obj-$(CONFIG_CPU_HAS_PMU) += pmu.o
AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
ifneq ($(CONFIG_ARCH_EBSA110),y)
diff --git a/arch/arm/kernel/pmu.c b/arch/arm/kernel/pmu.c
new file mode 100644
index 00000000000..a124312e343
--- /dev/null
+++ b/arch/arm/kernel/pmu.c
@@ -0,0 +1,103 @@
+/*
+ * linux/arch/arm/kernel/pmu.c
+ *
+ * Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <asm/pmu.h>
+
+/*
+ * Define the IRQs for the system. We could use something like a platform
+ * device but that seems fairly heavyweight for this. Also, the performance
+ * counters can't be removed or hotplugged.
+ *
+ * Ordering is important: init_pmu() will use the ordering to set the affinity
+ * to the corresponding core. e.g. the first interrupt will go to cpu 0, the
+ * second goes to cpu 1 etc.
+ */
+static const int irqs[] = {
+#if defined(CONFIG_ARCH_OMAP2)
+ 3,
+#elif defined(CONFIG_ARCH_BCMRING)
+ IRQ_PMUIRQ,
+#elif defined(CONFIG_MACH_REALVIEW_EB)
+ IRQ_EB11MP_PMU_CPU0,
+ IRQ_EB11MP_PMU_CPU1,
+ IRQ_EB11MP_PMU_CPU2,
+ IRQ_EB11MP_PMU_CPU3,
+#elif defined(CONFIG_ARCH_OMAP3)
+ INT_34XX_BENCH_MPU_EMUL,
+#elif defined(CONFIG_ARCH_IOP32X)
+ IRQ_IOP32X_CORE_PMU,
+#elif defined(CONFIG_ARCH_IOP33X)
+ IRQ_IOP33X_CORE_PMU,
+#elif defined(CONFIG_ARCH_PXA)
+ IRQ_PMU,
+#endif
+};
+
+static const struct pmu_irqs pmu_irqs = {
+ .irqs = irqs,
+ .num_irqs = ARRAY_SIZE(irqs),
+};
+
+static volatile long pmu_lock;
+
+const struct pmu_irqs *
+reserve_pmu(void)
+{
+ return test_and_set_bit_lock(0, &pmu_lock) ? ERR_PTR(-EBUSY) :
+ &pmu_irqs;
+}
+EXPORT_SYMBOL_GPL(reserve_pmu);
+
+int
+release_pmu(const struct pmu_irqs *irqs)
+{
+ if (WARN_ON(irqs != &pmu_irqs))
+ return -EINVAL;
+ clear_bit_unlock(0, &pmu_lock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(release_pmu);
+
+static int
+set_irq_affinity(int irq,
+ unsigned int cpu)
+{
+#ifdef CONFIG_SMP
+ int err = irq_set_affinity(irq, cpumask_of(cpu));
+ if (err)
+ pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
+ irq, cpu);
+ return err;
+#else
+ return 0;
+#endif
+}
+
+int
+init_pmu(void)
+{
+ int i, err = 0;
+
+ for (i = 0; i < pmu_irqs.num_irqs; ++i) {
+ err = set_irq_affinity(pmu_irqs.irqs[i], i);
+ if (err)
+ break;
+ }
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(init_pmu);