ARM: pmu: remove unused reservation mechanism

The PMU reservation mechanism was originally intended to allow OProfile
and perf-events to co-ordinate over access to the CPU PMU. Since then,
OProfile for ARM has moved to using perf as its backend, so the
reservation code is no longer used.

This patch removes the reservation code for the CPU PMU on ARM.
Signed-off-by: Will Deacon <will.deacon@arm.com>

MAINTAINERS

@@ -595,7 +595,6 @@ M:	Will Deacon <will.deacon@arm.com>
 S:	Maintained
 F:	arch/arm/kernel/perf_event*
 F:	arch/arm/oprofile/common.c
-F:	arch/arm/kernel/pmu.c
 F:	arch/arm/include/asm/pmu.h
 F:	arch/arm/kernel/hw_breakpoint.c
 F:	arch/arm/include/asm/hw_breakpoint.h

arch/arm/Kconfig

@@ -1179,12 +1179,6 @@ config XSCALE_PMU
 	depends on CPU_XSCALE
 	default y
 
-config CPU_HAS_PMU
-	depends on (CPU_V6 || CPU_V6K || CPU_V7 || XSCALE_PMU) && \
-		   (!ARCH_OMAP3 || OMAP3_EMU)
-	default y
-	bool
-
 config MULTI_IRQ_HANDLER
 	bool
 	help
@@ -1757,7 +1751,7 @@ config HIGHPTE
 
 config HW_PERF_EVENTS
 	bool "Enable hardware performance counter support for perf events"
-	depends on PERF_EVENTS && CPU_HAS_PMU
+	depends on PERF_EVENTS
 	default y
 	help
 	  Enable hardware performance counter support for perf events. If

arch/arm/include/asm/pmu.h

@@ -49,40 +49,6 @@ struct arm_pmu_platdata {
 	int (*runtime_suspend)(struct device *dev);
 };
 
-#ifdef CONFIG_CPU_HAS_PMU
-
-/**
- * reserve_pmu() - reserve the hardware performance counters
- *
- * Reserve the hardware performance counters in the system for exclusive use.
- * Returns 0 on success or -EBUSY if the lock is already held.
- */
-extern int
-reserve_pmu(enum arm_pmu_type type);
-
-/**
- * release_pmu() - Relinquish control of the performance counters
- *
- * Release the performance counters and allow someone else to use them.
- */
-extern void
-release_pmu(enum arm_pmu_type type);
-
-#else /* CONFIG_CPU_HAS_PMU */
-
-#include <linux/err.h>
-
-static inline int
-reserve_pmu(enum arm_pmu_type type)
-{
-	return -ENODEV;
-}
-
-static inline void
-release_pmu(enum arm_pmu_type type)	{ }
-
-#endif /* CONFIG_CPU_HAS_PMU */
-
 #ifdef CONFIG_HW_PERF_EVENTS
 
 /* The events for a given PMU register set. */

arch/arm/kernel/Makefile

@@ -69,7 +69,6 @@ obj-$(CONFIG_CPU_XSC3)		+= xscale-cp0.o
 obj-$(CONFIG_CPU_MOHAWK)	+= xscale-cp0.o
 obj-$(CONFIG_CPU_PJ4)		+= pj4-cp0.o
 obj-$(CONFIG_IWMMXT)		+= iwmmxt.o
-obj-$(CONFIG_CPU_HAS_PMU)	+= pmu.o
 obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
 AFLAGS_iwmmxt.o			:= -Wa,-mcpu=iwmmxt
 obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o

arch/arm/kernel/perf_event.c

@@ -377,7 +377,6 @@ armpmu_release_hardware(struct arm_pmu *armpmu)
 	}
 
 	pm_runtime_put_sync(&pmu_device->dev);
-	release_pmu(armpmu->type);
 }
 
 static int
@@ -391,12 +390,6 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
 	if (!pmu_device)
 		return -ENODEV;
 
-	err = reserve_pmu(armpmu->type);
-	if (err) {
-		pr_warning("unable to reserve pmu\n");
-		return err;
-	}
-
 	plat = dev_get_platdata(&pmu_device->dev);
 	if (plat && plat->handle_irq)
 		handle_irq = armpmu_platform_irq;
@@ -706,7 +699,6 @@ static void __init cpu_pmu_init(struct arm_pmu *armpmu)
 		raw_spin_lock_init(&events->pmu_lock);
 	}
 	armpmu->get_hw_events = armpmu_get_cpu_events;
-	armpmu->type = ARM_PMU_DEVICE_CPU;
 }
 
 /*

arch/arm/kernel/pmu.c

-/*
- *  linux/arch/arm/kernel/pmu.c
- *
- *  Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
- *  Copyright (C) 2010 ARM Ltd, Will Deacon
- *
- * 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/err.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-
-#include <asm/pmu.h>
-
-/*
- * PMU locking to ensure mutual exclusion between different subsystems.
- */
-static unsigned long pmu_lock[BITS_TO_LONGS(ARM_NUM_PMU_DEVICES)];
-
-int
-reserve_pmu(enum arm_pmu_type type)
-{
-	return test_and_set_bit_lock(type, pmu_lock) ? -EBUSY : 0;
-}
-EXPORT_SYMBOL_GPL(reserve_pmu);
-
-void
-release_pmu(enum arm_pmu_type type)
-{
-	clear_bit_unlock(type, pmu_lock);
-}
-EXPORT_SYMBOL_GPL(release_pmu);