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Commit 574b69cb authored by Will Deacon's avatar Will Deacon Committed by Russell King
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ARM: 6834/1: perf: reset counters on all CPUs during initialisation 



ARMv7 dictates that the interrupt-enable and count-enable registers for
each PMU counter are UNKNOWN following core reset.

This patch adds a new (optional) function pointer to struct arm_pmu for
resetting the PMU state during init. The reset function is called on
each CPU via an arch_initcall in the generic ARM perf_event code and
allows the PMU backend to write sane values to any UNKNOWN registers.

Acked-by: default avatarJean Pihet <j-pihet@ti.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent d25d3b4c

arch/arm/kernel/perf_event.c

+14 −0
Original line number Diff line number Diff line
@@ -79,6 +79,7 @@ struct arm_pmu { 
	void		(*write_counter)(int idx, u32 val);

	void		(*start)(void);

	void		(*stop)(void);

	void		(*reset)(void *);

	const unsigned	(*cache_map)[PERF_COUNT_HW_CACHE_MAX]

				    [PERF_COUNT_HW_CACHE_OP_MAX]

				    [PERF_COUNT_HW_CACHE_RESULT_MAX];
@@ -624,6 +625,19 @@ static struct pmu pmu = { 
#include "perf_event_v6.c"

#include "perf_event_v7.c"



/*

 * Ensure the PMU has sane values out of reset.

 * This requires SMP to be available, so exists as a separate initcall.

 */

static int __init

armpmu_reset(void)

{

	if (armpmu && armpmu->reset)

		return on_each_cpu(armpmu->reset, NULL, 1);

	return 0;

}

arch_initcall(armpmu_reset);



static int __init

init_hw_perf_events(void)

{

arch/arm/kernel/perf_event_v7.c

+16 −6
Original line number Diff line number Diff line
@@ -849,6 +849,18 @@ static int armv7pmu_get_event_idx(struct cpu_hw_events *cpuc, 
	}

}



static void armv7pmu_reset(void *info)

{

	u32 idx, nb_cnt = armpmu->num_events;



	/* The counter and interrupt enable registers are unknown at reset. */

	for (idx = 1; idx < nb_cnt; ++idx)

		armv7pmu_disable_event(NULL, idx);



	/* Initialize & Reset PMNC: C and P bits */

	armv7_pmnc_write(ARMV7_PMNC_P | ARMV7_PMNC_C);

}



static struct arm_pmu armv7pmu = {

	.handle_irq		= armv7pmu_handle_irq,

	.enable			= armv7pmu_enable_event,
@@ -858,17 +870,15 @@ static struct arm_pmu armv7pmu = { 
	.get_event_idx		= armv7pmu_get_event_idx,

	.start			= armv7pmu_start,

	.stop			= armv7pmu_stop,

	.reset			= armv7pmu_reset,

	.raw_event_mask		= 0xFF,

	.max_period		= (1LLU << 32) - 1,

};



static u32 __init armv7_reset_read_pmnc(void)

static u32 __init armv7_read_num_pmnc_events(void)

{

	u32 nb_cnt;



	/* Initialize & Reset PMNC: C and P bits */

	armv7_pmnc_write(ARMV7_PMNC_P | ARMV7_PMNC_C);



	/* Read the nb of CNTx counters supported from PMNC */

	nb_cnt = (armv7_pmnc_read() >> ARMV7_PMNC_N_SHIFT) & ARMV7_PMNC_N_MASK;
@@ -882,7 +892,7 @@ static const struct arm_pmu *__init armv7_a8_pmu_init(void) 
	armv7pmu.name		= "ARMv7 Cortex-A8";

	armv7pmu.cache_map	= &armv7_a8_perf_cache_map;

	armv7pmu.event_map	= &armv7_a8_perf_map;

	armv7pmu.num_events	= armv7_reset_read_pmnc();

	armv7pmu.num_events	= armv7_read_num_pmnc_events();

	return &armv7pmu;

}
@@ -892,7 +902,7 @@ static const struct arm_pmu *__init armv7_a9_pmu_init(void) 
	armv7pmu.name		= "ARMv7 Cortex-A9";

	armv7pmu.cache_map	= &armv7_a9_perf_cache_map;

	armv7pmu.event_map	= &armv7_a9_perf_map;

	armv7pmu.num_events	= armv7_reset_read_pmnc();

	armv7pmu.num_events	= armv7_read_num_pmnc_events();

	return &armv7pmu;

}

#else