// SPDX-License-Identifier: GPL-2.0
/*
* ARMv6 Performance counter handling code.
*
* Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
*
* ARMv6 has 2 configurable performance counters and a single cycle counter.
* They all share a single reset bit but can be written to zero so we can use
* that for a reset.
*
* The counters can't be individually enabled or disabled so when we remove
* one event and replace it with another we could get spurious counts from the
* wrong event. However, we can take advantage of the fact that the
* performance counters can export events to the event bus, and the event bus
* itself can be monitored. This requires that we *don't* export the events to
* the event bus. The procedure for disabling a configurable counter is:
* - change the counter to count the ETMEXTOUT[0] signal (0x20). This
* effectively stops the counter from counting.
* - disable the counter's interrupt generation (each counter has it's
* own interrupt enable bit).
* Once stopped, the counter value can be written as 0 to reset.
*
* To enable a counter:
* - enable the counter's interrupt generation.
* - set the new event type.
*
* Note: the dedicated cycle counter only counts cycles and can't be
* enabled/disabled independently of the others. When we want to disable the
* cycle counter, we have to just disable the interrupt reporting and start
* ignoring that counter. When re-enabling, we have to reset the value and
* enable the interrupt.
*/
#include <asm/cputype.h>
#include <asm/irq_regs.h>
#include <linux/of.h>
#include <linux/perf/arm_pmu.h>
#include <linux/platform_device.h>
enum armv6_perf_types {
ARMV6_PERFCTR_ICACHE_MISS = 0x0,
ARMV6_PERFCTR_IBUF_STALL = 0x1,
ARMV6_PERFCTR_DDEP_STALL = 0x2,
ARMV6_PERFCTR_ITLB_MISS = 0x3,
ARMV6_PERFCTR_DTLB_MISS = 0x4,
ARMV6_PERFCTR_BR_EXEC = 0x5,
ARMV6_PERFCTR_BR_MISPREDICT = 0x6,
ARMV6_PERFCTR_INSTR_EXEC = 0x7,
ARMV6_PERFCTR_DCACHE_HIT = 0x9,
ARMV6_PERFCTR_DCACHE_ACCESS = 0xA,
ARMV6_PERFCTR_DCACHE_MISS = 0xB,
ARMV6_PERFCTR_DCACHE_WBACK = 0xC,
ARMV6_PERFCTR_SW_PC_CHANGE = 0xD,
ARMV6_PERFCTR_MAIN_TLB_MISS = 0xF,
ARMV6_PERFCTR_EXPL_D_ACCESS = 0x10,
ARMV6_PERFCTR_LSU_FULL_STALL = 0x11,
ARMV6_PERFCTR_WBUF_DRAINED = 0x12,
ARMV6_PERFCTR_CPU_CYCLES = 0xFF,
ARMV6_PERFCTR_NOP = 0x20,
};
enum armv6_counters {
ARMV6_CYCLE_COUNTER = 0,
ARMV6_COUNTER0,
ARMV6_COUNTER1,
};
/*
* The hardware events that we support. We do support cache operations but
* we have harvard caches and no way to combine instruction and data
* accesses/misses in hardware.
*/
static const unsigned armv6_perf_map[PERF_COUNT_HW_MAX] = {
PERF_MAP_ALL_UNSUPPORTED,
[PERF_COUNT_HW_CPU_CYCLES] = ARMV6_PERFCTR_CPU_CYCLES,
[PERF_COUNT_HW_INSTRUCTIONS] = ARMV6_PERFCTR_INSTR_EXEC,
[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = ARMV6_PERFCTR_BR_EXEC,
[PERF_COUNT_HW_BRANCH_MISSES] = ARMV6_PERFCTR_BR_MISPREDICT,
[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = ARMV6_PERFCTR_IBUF_STALL,
[PERF_COUNT_HW_STALLED_CYCLES_BACKEND] = ARMV6_PERFCTR_LSU_FULL_STALL,
};
static const unsigned armv6_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
[PERF_COUNT_HW_CACHE_OP_MAX]
[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
PERF_CACHE_MAP_ALL_UNSUPPORTED,
/*
* The performance counters don't differentiate between read and write
* accesses/misses so this isn't strictly correct, but it's the best we
* can do. Writes and reads get combined.
*/
[C(L1D)][C(OP_READ)][C(RESULT_ACCESS)] = ARMV6_PERFCTR_DCACHE_ACCESS,
[C(L1D)][C(OP_READ)][C(RESULT_MISS)] = ARMV6_PERFCTR_DCACHE_MISS,
[C(L1D)][C(OP_WRITE)][C(RESULT_ACCESS)] = ARMV6_PERFCTR_DCACHE_ACCESS,
[C(L1D)][C(OP_WRITE)][C(RESULT_MISS)] = ARMV6_PERFCTR_DCACHE_MISS,
[C(L1I)][C(OP_READ)][C(RESULT_MISS)] = ARMV6_PERFCTR_ICACHE_MISS,
/*
* The ARM performance counters can count micro DTLB misses, micro ITLB
* misses and main TLB misses. There isn't an event for TLB misses, so
* use the micro misses here and if users want the main TLB misses they
* can use a raw counter.
*/
[C(DTLB)][C(OP_READ)][C(RESULT_MISS)] = ARMV6_PERFCTR_DTLB_MISS,
[C(DTLB)][C(OP_WRITE)][C(RESULT_MISS)] = ARMV6_PERFCTR_DTLB_MISS,
[C(ITLB)][C(OP_READ)][C(RESULT_MISS)] = ARMV6_PERFCTR_ITLB_MISS,
[C(ITLB)][C(OP_WRITE)][C(RESULT_MISS)] = ARMV6_PERFCTR_ITLB_MISS,
};
static inline unsigned long
armv6_pmcr_read(void)
{
u32 val;
asm volatile("mrc p15, 0, %0, c15, c12, 0" : "=r"(val));
return val;
}
static inline void
armv6_pmcr_write(unsigned long val)
{
asm volatile("mcr p15, 0, %0, c15, c12, 0" : : "r"(val));
}
#define ARMV6_PMCR_ENABLE (1 << 0)
#define ARMV6_PMCR_CTR01_RESET (1 << 1)
#define ARMV6_PMCR_CCOUNT_RESET (1 << 2)
#define ARMV6_PMCR_CCOUNT_DIV (1 << 3)
#define ARMV6_PMCR_COUNT0_IEN (1 << 4)
#define ARMV6_PMCR_COUNT1_IEN (1 << 5)
#define ARMV6_PMCR_CCOUNT_IEN (1 << 6)
#define ARMV6_PMCR_COUNT0_OVERFLOW (1 << 8)
#define ARMV6_PMCR_COUNT1_OVERFLOW (1 << 9)
#define ARMV6_PMCR_CCOUNT_OVERFLOW (1 << 10)
#define ARMV6_PMCR_EVT_COUNT0_SHIFT 20
#define ARMV6_PMCR_EVT_COUNT0_MASK (0xFF << ARMV6_PMCR_EVT_COUNT0_SHIFT)
#define ARMV6_PMCR_EVT_COUNT1_SHIFT 12
#define ARMV6_PMCR_EVT_COUNT1_MASK (0xFF << ARMV6_PMCR_EVT_COUNT1_SHIFT)
#define ARMV6_PMCR_OVERFLOWED_MASK \
(ARMV6_PMCR_COUNT0_OVERFLOW | ARMV6_PMCR_COUNT1_OVERFLOW | \
ARMV6_PMCR_CCOUNT_OVERFLOW)
static inline int
armv6_pmcr_has_overflowed(unsigned long pmcr)
{
return pmcr & ARMV6_PMCR_OVERFLOWED_MASK;
}
static inline int
armv6_pmcr_counter_has_overflowed(unsigned long pmcr,
enum armv6_counters counter)
{
int ret = 0;
if (ARMV6_CYCLE_COUNTER == counter)
ret = pmcr & ARMV6_PMCR_CCOUNT_OVERFLOW;
else if (ARMV6_COUNTER0 == counter)
ret = pmcr & ARMV6_PMCR_COUNT0_OVERFLOW;
else if (ARMV6_COUNTER1 == counter)
ret = pmcr & ARMV6_PMCR_COUNT1_OVERFLOW;
else
WARN_ONCE(1, "invalid counter number (%d)\n", counter);
return ret;
}
static inline u64 armv6pmu_read_counter(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
int counter = hwc->idx;
unsigned long value = 0;
if (ARMV6_CYCLE_COUNTER == counter)
asm volatile("mrc p15, 0, %0, c15, c12, 1" : "=r"(value));
else if (ARMV6_COUNTER0 == counter)
asm volatile("mrc p15, 0, %0, c15, c12, 2" : "=r"(value));
else if (ARMV6_COUNTER1 == counter)
asm volatile("mrc p15, 0, %0, c15, c12, 3" : "=r"(value));
else
WARN_ONCE(1, "invalid counter number (%d)\n", counter);
return value;
}
static inline void armv6pmu_write_counter(struct perf_event *event, u64 value)
{
struct hw_perf_event *hwc = &event->hw;
int counter = hwc->idx;
if (ARMV6_CYCLE_COUNTER == counter)
asm volatile("mcr p15, 0, %0, c15, c12, 1" : : "r"(value));
else if (ARMV6_COUNTER0 == counter)
asm volatile("mcr p15, 0, %0, c15, c12, 2" : : "r"(value));
else if (ARMV6_COUNTER1 == counter)
asm volatile("mcr p15, 0, %0, c15, c12, 3" : : "r"(value));
else
WARN_ONCE(1, "invalid counter number (%d)\n", counter);
}
static void armv6pmu_enable_event(struct perf_event *event)
{
unsigned long val, mask, evt;
struct hw_perf_event *hwc = &event->hw;
int idx = hwc->idx;
if (ARMV6_CYCLE_COUNTER == idx) {
mask = 0;
evt = ARMV6_PMCR_CCOUNT_IEN;
} else if (ARMV6_COUNTER0 == idx) {
mask = ARMV6_PMCR_EVT_COUNT0_MASK;
evt = (hwc->config_base << ARMV6_PMCR_EVT_COUNT0_SHIFT) |
ARMV6_PMCR_COUNT0_IEN;
} else if (ARMV6_COUNTER1 == idx) {
mask = ARMV6_PMCR_EVT_COUNT1_MASK;
evt = (hwc->config_base << ARMV6_PMCR_EVT_COUNT1_SHIFT) |
ARMV6_PMCR_COUNT1_IEN;
} else {
WARN_ONCE(1, "invalid counter number (%d)\n", idx);
return;
}
/*
* Mask out the current event and set the counter to count the event
* that we're interested in.
*/
val = armv6_pmcr_read();
val &= ~mask;
val |= evt;
armv6_pmcr_write(val);
}
static irqreturn_t
armv6pmu_handle_irq(struct arm_pmu *cpu_pmu)
{
unsigned long pmcr = armv6_pmcr_read();
struct perf_sample_data data;
struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events);
struct pt_regs *regs;
int idx;
if (!armv6_pmcr_has_overflowed(pmcr))
return IRQ_NONE;
regs = get_irq_regs();
/*
* The interrupts are cleared by writing the overflow flags back to
* the control register. All of the other bits don't have any effect
* if they are rewritten, so write the whole value back.
*/
armv6_pmcr_write(pmcr);
for (idx = 0; idx < cpu_pmu->num_events; ++idx) {
struct perf_event *event = cpuc->events[idx];
struct hw_perf_event *hwc;
/* Ignore if we don't have an event. */
if (!event)
continue;
/*
* We have a single interrupt for all counters. Check that
* each counter has overflowed before we process it.
*/
if (!armv6_pmcr_counter_has_overflowed(pmcr, idx))
continue;
hwc = &event->hw;
armpmu_event_update(event);
perf_sample_data_init(&data, 0, hwc->last_period);
if (!armpmu_event_set_period(event))
continue;
if (perf_event_overflow(event, &data, regs))
cpu_pmu->disable(event);
}
/*
* Handle the pending perf events.
*
* Note: this call *must* be run with interrupts disabled. For
* platforms that can have the PMU interrupts raised as an NMI, this
* will not work.
*/
irq_work_run();
return IRQ_HANDLED;
}
static void armv6pmu_start(struct arm_pmu *cpu_pmu)
{
unsigned long val;
val = armv6_pmcr_read();
val |= ARMV6_PMCR_ENABLE;
armv6_pmcr_write(val);
}
static void armv6pmu_stop(struct arm_pmu *cpu_pmu)
{
unsigned long val;
val = armv6_pmcr_read();
val &= ~ARMV6_PMCR_ENABLE;
armv6_pmcr_write(val);
}
static int
armv6pmu_get_event_idx(struct pmu_hw_events *cpuc,
struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
/* Always place a cycle counter into the cycle counter. */
if (ARMV6_PERFCTR_CPU_CYCLES == hwc->config_base) {
if (test_and_set_bit(ARMV6_CYCLE_COUNTER, cpuc->used_mask))
return -EAGAIN;
return ARMV6_CYCLE_COUNTER;
} else {
/*
* For anything other than a cycle counter, try and use
* counter0 and counter1.
*/
if (!test_and_set_bit(ARMV6_COUNTER1, cpuc->used_mask))
return ARMV6_COUNTER1;
if (!test_and_set_bit(ARMV6_COUNTER0, cpuc->used_mask))
return ARMV6_COUNTER0;
/* The counters are all in use. */
return -EAGAIN;
}
}
static void armv6pmu_clear_event_idx(struct pmu_hw_events *cpuc,
struct perf_event *event)
{
clear_bit(event->hw.idx, cpuc->used_mask);
}
static void armv6pmu_disable_event(struct perf_event *event)
{
unsigned long val, mask, evt;
struct hw_perf_event *hwc = &event->hw;
int idx = hwc->idx;
if (ARMV6_CYCLE_COUNTER == idx) {
mask = ARMV6_PMCR_CCOUNT_IEN;
evt = 0;
} else if (ARMV6_COUNTER0 == idx) {
mask = ARMV6_PMCR_COUNT0_IEN | ARMV6_PMCR_EVT_COUNT0_MASK;
evt = ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT0_SHIFT;
} else if (ARMV6_COUNTER1 == idx) {
mask = ARMV6_PMCR_COUNT1_IEN | ARMV6_PMCR_EVT_COUNT1_MASK;
evt = ARMV6_PERFCTR_NOP << ARMV6_PMCR_EVT_COUNT1_SHIFT;
} else {
WARN_ONCE(1, "invalid counter number (%d)\n", idx);
return;
}
/*
* Mask out the current event and set the counter to count the number
* of ETM bus signal assertion cycles. The external reporting should
* be disabled and so this should never increment.
*/
val = armv6_pmcr_read();
val &= ~mask;
val |= evt;
armv6_pmcr_write(val);
}
static int armv6_map_event(struct perf_event *event)
{
return armpmu_map_event(event, &armv6_perf_map,
&armv6_perf_cache_map, 0xFF);
}
static void armv6pmu_init(struct arm_pmu *cpu_pmu)
{
cpu_pmu->handle_irq = armv6pmu_handle_irq;
cpu_pmu->enable = armv6pmu_enable_event;
cpu_pmu->disable = armv6pmu_disable_event;
cpu_pmu->read_counter = armv6pmu_read_counter;
cpu_pmu->write_counter = armv6pmu_write_counter;
cpu_pmu->get_event_idx = armv6pmu_get_event_idx;
cpu_pmu->clear_event_idx = armv6pmu_clear_event_idx;
cpu_pmu->start = armv6pmu_start;
cpu_pmu->stop = armv6pmu_stop;
cpu_pmu->map_event = armv6_map_event;
cpu_pmu->num_events = 3;
}
static int armv6_1136_pmu_init(struct arm_pmu *cpu_pmu)
{
armv6pmu_init(cpu_pmu);
cpu_pmu->name = "armv6_1136";
return 0;
}
static int armv6_1176_pmu_init(struct arm_pmu *cpu_pmu)
{
armv6pmu_init(cpu_pmu);
cpu_pmu->name = "armv6_1176";
return 0;
}
static const struct of_device_id armv6_pmu_of_device_ids[] = {
{.compatible = "arm,arm1176-pmu", .data = armv6_1176_pmu_init},
{.compatible = "arm,arm1136-pmu", .data = armv6_1136_pmu_init},
{ /* sentinel value */ }
};
static int armv6_pmu_device_probe(struct platform_device *pdev)
{
return arm_pmu_device_probe(pdev, armv6_pmu_of_device_ids, NULL);
}
static struct platform_driver armv6_pmu_driver = {
.driver = {
.name = "armv6-pmu",
.of_match_table = armv6_pmu_of_device_ids,
},
.probe = armv6_pmu_device_probe,
};
builtin_platform_driver(armv6_pmu_driver);
Codebase Browser
linux