Merge branch 'will/for-next/perf' into for-next/core

* will/for-next/perf:
arm64: pmuv3: use arm_pmu ACPI framework
arm64: pmuv3: handle !PMUv3 when probing
drivers/perf: arm_pmu: add ACPI framework
arm64: add function to get a cpu's MADT GICC table
drivers/perf: arm_pmu: split out platform device probe logic
drivers/perf: arm_pmu: move irq request/free into probe
drivers/perf: arm_pmu: split cpu-local irq request/free
drivers/perf: arm_pmu: rename irq request/free functions
drivers/perf: arm_pmu: handle no platform_device
drivers/perf: arm_pmu: simplify cpu_pmu_request_irqs()
drivers/perf: arm_pmu: factor out pmu registration
drivers/perf: arm_pmu: fold init into alloc
drivers/perf: arm_pmu: define armpmu_init_fn
drivers/perf: arm_pmu: remove pointless PMU disabling
perf: qcom: Add L3 cache PMU driver
drivers/perf: arm_pmu: split irq request from enable
drivers/perf: arm_pmu: manage interrupts per-cpu
drivers/perf: arm_pmu: rework per-cpu allocation
MAINTAINERS: Add file patterns for perf device tree bindings

Documentation/perf/qcom_l3_pmu.txt

···
+Qualcomm Datacenter Technologies L3 Cache Performance Monitoring Unit (PMU)
+===========================================================================
+
+This driver supports the L3 cache PMUs found in Qualcomm Datacenter Technologies
+Centriq SoCs. The L3 cache on these SOCs is composed of multiple slices, shared
+by all cores within a socket. Each slice is exposed as a separate uncore perf
+PMU with device name l3cache_<socket>_<instance>. User space is responsible
+for aggregating across slices.
+
+The driver provides a description of its available events and configuration
+options in sysfs, see /sys/devices/l3cache*. Given that these are uncore PMUs
+the driver also exposes a "cpumask" sysfs attribute which contains a mask
+consisting of one CPU per socket which will be used to handle all the PMU
+events on that socket.
+
+The hardware implements 32bit event counters and has a flat 8bit event space
+exposed via the "event" format attribute. In addition to the 32bit physical
+counters the driver supports virtual 64bit hardware counters by using hardware
+counter chaining. This feature is exposed via the "lc" (long counter) format
+flag. E.g.:
+
+  perf stat -e l3cache_0_0/read-miss,lc/
+
+Given that these are uncore PMUs the driver does not support sampling, therefore
+"perf record" will not work. Per-task perf sessions are not supported.

MAINTAINERS

···
 F:	drivers/perf/*
 F:	include/linux/perf/arm_pmu.h
 F:	Documentation/devicetree/bindings/arm/pmu.txt
+F:	Documentation/devicetree/bindings/perf/
 
 ARM PORT
 M:	Russell King <[e-mail]>

arch/arm64/include/asm/acpi.h

···
 	return true;
 }
 
+struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu);
+
 static inline void arch_fix_phys_package_id(int num, u32 slot) { }
 void __init acpi_init_cpus(void);
 

arch/arm64/kernel/perf_event.c

···
 				ARMV8_PMU_EVTYPE_EVENT);
 }
 
+struct armv8pmu_probe_info {
+	struct arm_pmu *pmu;
+	bool present;
+};
+
 static void __armv8pmu_probe_pmu(void *info)
 {
-	struct arm_pmu *cpu_pmu = info;
+	struct armv8pmu_probe_info *probe = info;
+	struct arm_pmu *cpu_pmu = probe->pmu;
+	u64 dfr0, pmuver;
 	u32 pmceid[2];
+
+	dfr0 = read_sysreg(id_aa64dfr0_el1);
+	pmuver = cpuid_feature_extract_unsigned_field(dfr0,
+			ID_AA64DFR0_PMUVER_SHIFT);
+	if (pmuver != 1)
+		return;
+
+	probe->present = true;
 
 	/* Read the nb of CNTx counters supported from PMNC */
 	cpu_pmu->num_events = (armv8pmu_pmcr_read() >> ARMV8_PMU_PMCR_N_SHIFT)
···
 
 static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu)
 {
-	return smp_call_function_any(&cpu_pmu->supported_cpus,
+	struct armv8pmu_probe_info probe = {
+		.pmu = cpu_pmu,
+		.present = false,
+	};
+	int ret;
+
+	ret = smp_call_function_any(&cpu_pmu->supported_cpus,
 				    __armv8pmu_probe_pmu,
-				    cpu_pmu, 1);
+				    &probe, 1);
+	if (ret)
+		return ret;
+
+	return probe.present ? 0 : -ENODEV;
 }
 
-static void armv8_pmu_init(struct arm_pmu *cpu_pmu)
+static int armv8_pmu_init(struct arm_pmu *cpu_pmu)
 {
+	int ret = armv8pmu_probe_pmu(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->handle_irq		= armv8pmu_handle_irq,
 	cpu_pmu->enable			= armv8pmu_enable_event,
 	cpu_pmu->disable		= armv8pmu_disable_event,
···
 	cpu_pmu->reset			= armv8pmu_reset,
 	cpu_pmu->max_period		= (1LLU << 32) - 1,
 	cpu_pmu->set_event_filter	= armv8pmu_set_event_filter;
+
+	return 0;
 }
 
 static int armv8_pmuv3_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_pmuv3";
 	cpu_pmu->map_event		= armv8_pmuv3_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static int armv8_a53_pmu_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_cortex_a53";
 	cpu_pmu->map_event		= armv8_a53_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static int armv8_a57_pmu_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_cortex_a57";
 	cpu_pmu->map_event		= armv8_a57_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static int armv8_a72_pmu_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_cortex_a72";
 	cpu_pmu->map_event		= armv8_a57_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static int armv8_thunder_pmu_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_cavium_thunder";
 	cpu_pmu->map_event		= armv8_thunder_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static int armv8_vulcan_pmu_init(struct arm_pmu *cpu_pmu)
 {
-	armv8_pmu_init(cpu_pmu);
+	int ret = armv8_pmu_init(cpu_pmu);
+	if (ret)
+		return ret;
+
 	cpu_pmu->name			= "armv8_brcm_vulcan";
 	cpu_pmu->map_event		= armv8_vulcan_map_event;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] =
 		&armv8_pmuv3_events_attr_group;
 	cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
 		&armv8_pmuv3_format_attr_group;
-	return armv8pmu_probe_pmu(cpu_pmu);
+
+	return 0;
 }
 
 static const struct of_device_id armv8_pmu_of_device_ids[] = {
···
 	{},
 };
 
-/*
- * Non DT systems have their micro/arch events probed at run-time.
- * A fairly complete list of generic events are provided and ones that
- * aren't supported by the current PMU are disabled.
- */
-static const struct pmu_probe_info armv8_pmu_probe_table[] = {
-	PMU_PROBE(0, 0, armv8_pmuv3_init), /* enable all defined counters */
-	{ /* sentinel value */ }
-};
-
 static int armv8_pmu_device_probe(struct platform_device *pdev)
 {
-	if (acpi_disabled)
-		return arm_pmu_device_probe(pdev, armv8_pmu_of_device_ids,
-					    NULL);
-
-	return arm_pmu_device_probe(pdev, armv8_pmu_of_device_ids,
-				    armv8_pmu_probe_table);
+	return arm_pmu_device_probe(pdev, armv8_pmu_of_device_ids, NULL);
 }
 
 static struct platform_driver armv8_pmu_driver = {
···
 	.probe		= armv8_pmu_device_probe,
 };
 
-builtin_platform_driver(armv8_pmu_driver);
+static int __init armv8_pmu_driver_init(void)
+{
+	if (acpi_disabled)
+		return platform_driver_register(&armv8_pmu_driver);
+	else
+		return arm_pmu_acpi_probe(armv8_pmuv3_init);
+}
+device_initcall(armv8_pmu_driver_init)

arch/arm64/kernel/smp.c

···
 static unsigned int cpu_count = 1;
 
 #ifdef CONFIG_ACPI
+static struct acpi_madt_generic_interrupt cpu_madt_gicc[NR_CPUS];
+
+struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu)
+{
+	return &cpu_madt_gicc[cpu];
+}
+
 /*
  * acpi_map_gic_cpu_interface - parse processor MADT entry
  *
···
 			return;
 		}
 		bootcpu_valid = true;
+		cpu_madt_gicc[0] = *processor;
 		early_map_cpu_to_node(0, acpi_numa_get_nid(0, hwid));
 		return;
 	}
···
 
 	/* map the logical cpu id to cpu MPIDR */
 	cpu_logical_map(cpu_count) = hwid;
+
+	cpu_madt_gicc[cpu_count] = *processor;
 
 	/*
 	 * Set-up the ACPI parking protocol cpu entries

drivers/perf/Kconfig

···
 	  Say y if you want to use CPU performance monitors on ARM-based
 	  systems.
 
+config ARM_PMU_ACPI
+	depends on ARM_PMU && ACPI
+	def_bool y
+
 config QCOM_L2_PMU
 	bool "Qualcomm Technologies L2-cache PMU"
 	depends on ARCH_QCOM && ARM64 && PERF_EVENTS && ACPI
···
 	  in Qualcomm Technologies processors.
 	  Adds the L2 cache PMU into the perf events subsystem for
 	  monitoring L2 cache events.
+
+config QCOM_L3_PMU
+	bool "Qualcomm Technologies L3-cache PMU"
+	depends on ARCH_QCOM && ARM64 && PERF_EVENTS && ACPI
+	select QCOM_IRQ_COMBINER
+	help
+	   Provides support for the L3 cache performance monitor unit (PMU)
+	   in Qualcomm Technologies processors.
+	   Adds the L3 cache PMU into the perf events subsystem for
+	   monitoring L3 cache events.
 
 config XGENE_PMU
         depends on PERF_EVENTS && ARCH_XGENE

drivers/perf/Makefile

···
-obj-$(CONFIG_ARM_PMU) += arm_pmu.o
+obj-$(CONFIG_ARM_PMU) += arm_pmu.o arm_pmu_platform.o
+obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
+obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o

drivers/perf/arm_pmu.c

···
 #include <linux/cpu_pm.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
-#include <linux/of_device.h>
 #include <linux/perf/arm_pmu.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
···
 #include <linux/irq.h>
 #include <linux/irqdesc.h>
 
-#include <asm/cputype.h>
 #include <asm/irq_regs.h>
 
 static int
···
 	struct pmu_hw_events *hw_events = this_cpu_ptr(armpmu->hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	int idx;
-	int err = 0;
 
 	/* An event following a process won't be stopped earlier */
 	if (!cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus))
 		return -ENOENT;
 
-	perf_pmu_disable(event->pmu);
-
 	/* If we don't have a space for the counter then finish early. */
 	idx = armpmu->get_event_idx(hw_events, event);
-	if (idx < 0) {
-		err = idx;
-		goto out;
-	}
+	if (idx < 0)
+		return idx;
 
 	/*
 	 * If there is an event in the counter we are going to use then make
···
 	/* Propagate our changes to the userspace mapping. */
 	perf_event_update_userpage(event);
 
-out:
-	perf_pmu_enable(event->pmu);
-	return err;
+	return 0;
 }
 
 static int
···
 	return 0;
 }
 
+static struct arm_pmu_platdata *armpmu_get_platdata(struct arm_pmu *armpmu)
+{
+	struct platform_device *pdev = armpmu->plat_device;
+
+	return pdev ? dev_get_platdata(&pdev->dev) : NULL;
+}
+
 static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 {
 	struct arm_pmu *armpmu;
-	struct platform_device *plat_device;
 	struct arm_pmu_platdata *plat;
 	int ret;
 	u64 start_clock, finish_clock;
···
 	 * dereference.
 	 */
 	armpmu = *(void **)dev;
-	plat_device = armpmu->plat_device;
-	plat = dev_get_platdata(&plat_device->dev);
+
+	plat = armpmu_get_platdata(armpmu);
 
 	start_clock = sched_clock();
 	if (plat && plat->handle_irq)
···
 
 	perf_sample_event_took(finish_clock - start_clock);
 	return ret;
-}
-
-static void
-armpmu_release_hardware(struct arm_pmu *armpmu)
-{
-	armpmu->free_irq(armpmu);
-}
-
-static int
-armpmu_reserve_hardware(struct arm_pmu *armpmu)
-{
-	int err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
-	if (err) {
-		armpmu_release_hardware(armpmu);
-		return err;
-	}
-
-	return 0;
-}
-
-static void
-hw_perf_event_destroy(struct perf_event *event)
-{
-	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
-	atomic_t *active_events	 = &armpmu->active_events;
-	struct mutex *pmu_reserve_mutex = &armpmu->reserve_mutex;
-
-	if (atomic_dec_and_mutex_lock(active_events, pmu_reserve_mutex)) {
-		armpmu_release_hardware(armpmu);
-		mutex_unlock(pmu_reserve_mutex);
-	}
 }
 
 static int
···
 static int armpmu_event_init(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
-	int err = 0;
-	atomic_t *active_events = &armpmu->active_events;
 
 	/*
 	 * Reject CPU-affine events for CPUs that are of a different class to
···
 	if (armpmu->map_event(event) == -ENOENT)
 		return -ENOENT;
 
-	event->destroy = hw_perf_event_destroy;
-
-	if (!atomic_inc_not_zero(active_events)) {
-		mutex_lock(&armpmu->reserve_mutex);
-		if (atomic_read(active_events) == 0)
-			err = armpmu_reserve_hardware(armpmu);
-
-		if (!err)
-			atomic_inc(active_events);
-		mutex_unlock(&armpmu->reserve_mutex);
-	}
-
-	if (err)
-		return err;
-
-	err = __hw_perf_event_init(event);
-	if (err)
-		hw_perf_event_destroy(event);
-
-	return err;
+	return __hw_perf_event_init(event);
 }
 
 static void armpmu_enable(struct pmu *pmu)
···
 	.attrs = armpmu_common_attrs,
 };
 
-static void armpmu_init(struct arm_pmu *armpmu)
-{
-	atomic_set(&armpmu->active_events, 0);
-	mutex_init(&armpmu->reserve_mutex);
-
-	armpmu->pmu = (struct pmu) {
-		.pmu_enable	= armpmu_enable,
-		.pmu_disable	= armpmu_disable,
-		.event_init	= armpmu_event_init,
-		.add		= armpmu_add,
-		.del		= armpmu_del,
-		.start		= armpmu_start,
-		.stop		= armpmu_stop,
-		.read		= armpmu_read,
-		.filter_match	= armpmu_filter_match,
-		.attr_groups	= armpmu->attr_groups,
-	};
-	armpmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =
-		&armpmu_common_attr_group;
-}
-
 /* Set at runtime when we know what CPU type we are. */
 static struct arm_pmu *__oprofile_cpu_pmu;
 
···
 }
 EXPORT_SYMBOL_GPL(perf_num_counters);
 
-static void cpu_pmu_enable_percpu_irq(void *data)
+void armpmu_free_irq(struct arm_pmu *armpmu, int cpu)
 {
-	int irq = *(int *)data;
+	struct pmu_hw_events __percpu *hw_events = armpmu->hw_events;
+	int irq = per_cpu(hw_events->irq, cpu);
 
-	enable_percpu_irq(irq, IRQ_TYPE_NONE);
-}
+	if (!cpumask_test_and_clear_cpu(cpu, &armpmu->active_irqs))
+		return;
 
-static void cpu_pmu_disable_percpu_irq(void *data)
-{
-	int irq = *(int *)data;
-
-	disable_percpu_irq(irq);
-}
-
-static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu)
-{
-	int i, irq, irqs;
-	struct platform_device *pmu_device = cpu_pmu->plat_device;
-	struct pmu_hw_events __percpu *hw_events = cpu_pmu->hw_events;
-
-	irqs = min(pmu_device->num_resources, num_possible_cpus());
-
-	irq = platform_get_irq(pmu_device, 0);
-	if (irq > 0 && irq_is_percpu(irq)) {
-		on_each_cpu_mask(&cpu_pmu->supported_cpus,
-				 cpu_pmu_disable_percpu_irq, &irq, 1);
+	if (irq_is_percpu(irq)) {
 		free_percpu_irq(irq, &hw_events->percpu_pmu);
-	} else {
-		for (i = 0; i < irqs; ++i) {
-			int cpu = i;
-
-			if (cpu_pmu->irq_affinity)
-				cpu = cpu_pmu->irq_affinity[i];
-
-			if (!cpumask_test_and_clear_cpu(cpu, &cpu_pmu->active_irqs))
-				continue;
-			irq = platform_get_irq(pmu_device, i);
-			if (irq > 0)
-				free_irq(irq, per_cpu_ptr(&hw_events->percpu_pmu, cpu));
-		}
+		cpumask_clear(&armpmu->active_irqs);
+		return;
 	}
+
+	free_irq(irq, per_cpu_ptr(&hw_events->percpu_pmu, cpu));
 }
 
-static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
+void armpmu_free_irqs(struct arm_pmu *armpmu)
 {
-	int i, err, irq, irqs;
-	struct platform_device *pmu_device = cpu_pmu->plat_device;
-	struct pmu_hw_events __percpu *hw_events = cpu_pmu->hw_events;
+	int cpu;
 
-	if (!pmu_device)
-		return -ENODEV;
+	for_each_cpu(cpu, &armpmu->supported_cpus)
+		armpmu_free_irq(armpmu, cpu);
+}
 
-	irqs = min(pmu_device->num_resources, num_possible_cpus());
-	if (irqs < 1) {
-		pr_warn_once("perf/ARM: No irqs for PMU defined, sampling events not supported\n");
+int armpmu_request_irq(struct arm_pmu *armpmu, int cpu)
+{
+	int err = 0;
+	struct pmu_hw_events __percpu *hw_events = armpmu->hw_events;
+	const irq_handler_t handler = armpmu_dispatch_irq;
+	int irq = per_cpu(hw_events->irq, cpu);
+	if (!irq)
 		return 0;
-	}
 
-	irq = platform_get_irq(pmu_device, 0);
-	if (irq > 0 && irq_is_percpu(irq)) {
+	if (irq_is_percpu(irq) && cpumask_empty(&armpmu->active_irqs)) {
 		err = request_percpu_irq(irq, handler, "arm-pmu",
 					 &hw_events->percpu_pmu);
-		if (err) {
-			pr_err("unable to request IRQ%d for ARM PMU counters\n",
-				irq);
-			return err;
-		}
+	} else if (irq_is_percpu(irq)) {
+		int other_cpu = cpumask_first(&armpmu->active_irqs);
+		int other_irq = per_cpu(hw_events->irq, other_cpu);
 
-		on_each_cpu_mask(&cpu_pmu->supported_cpus,
-				 cpu_pmu_enable_percpu_irq, &irq, 1);
+		if (irq != other_irq) {
+			pr_warn("mismatched PPIs detected.\n");
+			err = -EINVAL;
+		}
 	} else {
-		for (i = 0; i < irqs; ++i) {
-			int cpu = i;
-
-			err = 0;
-			irq = platform_get_irq(pmu_device, i);
-			if (irq < 0)
-				continue;
-
-			if (cpu_pmu->irq_affinity)
-				cpu = cpu_pmu->irq_affinity[i];
-
-			/*
-			 * If we have a single PMU interrupt that we can't shift,
-			 * assume that we're running on a uniprocessor machine and
-			 * continue. Otherwise, continue without this interrupt.
-			 */
-			if (irq_set_affinity(irq, cpumask_of(cpu)) && irqs > 1) {
-				pr_warn("unable to set irq affinity (irq=%d, cpu=%u)\n",
-					irq, cpu);
-				continue;
-			}
-
-			err = request_irq(irq, handler,
-					  IRQF_NOBALANCING | IRQF_NO_THREAD, "arm-pmu",
-					  per_cpu_ptr(&hw_events->percpu_pmu, cpu));
-			if (err) {
-				pr_err("unable to request IRQ%d for ARM PMU counters\n",
-					irq);
-				return err;
-			}
-
-			cpumask_set_cpu(cpu, &cpu_pmu->active_irqs);
-		}
+		err = request_irq(irq, handler,
+				  IRQF_NOBALANCING | IRQF_NO_THREAD, "arm-pmu",
+				  per_cpu_ptr(&hw_events->percpu_pmu, cpu));
 	}
 
+	if (err) {
+		pr_err("unable to request IRQ%d for ARM PMU counters\n",
+			irq);
+		return err;
+	}
+
+	cpumask_set_cpu(cpu, &armpmu->active_irqs);
+
 	return 0;
+}
+
+int armpmu_request_irqs(struct arm_pmu *armpmu)
+{
+	int cpu, err;
+
+	for_each_cpu(cpu, &armpmu->supported_cpus) {
+		err = armpmu_request_irq(armpmu, cpu);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
+static int armpmu_get_cpu_irq(struct arm_pmu *pmu, int cpu)
+{
+	struct pmu_hw_events __percpu *hw_events = pmu->hw_events;
+	return per_cpu(hw_events->irq, cpu);
 }
 
 /*
···
 static int arm_perf_starting_cpu(unsigned int cpu, struct hlist_node *node)
 {
 	struct arm_pmu *pmu = hlist_entry_safe(node, struct arm_pmu, node);
+	int irq;
 
 	if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
 		return 0;
 	if (pmu->reset)
 		pmu->reset(pmu);
+
+	irq = armpmu_get_cpu_irq(pmu, cpu);
+	if (irq) {
+		if (irq_is_percpu(irq)) {
+			enable_percpu_irq(irq, IRQ_TYPE_NONE);
+			return 0;
+		}
+
+		if (irq_force_affinity(irq, cpumask_of(cpu)) &&
+		    num_possible_cpus() > 1) {
+			pr_warn("unable to set irq affinity (irq=%d, cpu=%u)\n",
+				irq, cpu);
+		}
+	}
+
+	return 0;
+}
+
+static int arm_perf_teardown_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct arm_pmu *pmu = hlist_entry_safe(node, struct arm_pmu, node);
+	int irq;
+
+	if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
+		return 0;
+
+	irq = armpmu_get_cpu_irq(pmu, cpu);
+	if (irq && irq_is_percpu(irq))
+		disable_percpu_irq(irq);
+
 	return 0;
 }
 
···
 static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
 {
 	int err;
-	int cpu;
-	struct pmu_hw_events __percpu *cpu_hw_events;
 
-	cpu_hw_events = alloc_percpu(struct pmu_hw_events);
-	if (!cpu_hw_events)
-		return -ENOMEM;
-
-	err = cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_STARTING,
-					       &cpu_pmu->node);
+	err = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_STARTING,
+				       &cpu_pmu->node);
 	if (err)
-		goto out_free;
+		goto out;
 
 	err = cpu_pm_pmu_register(cpu_pmu);
 	if (err)
 		goto out_unregister;
-
-	for_each_possible_cpu(cpu) {
-		struct pmu_hw_events *events = per_cpu_ptr(cpu_hw_events, cpu);
-		raw_spin_lock_init(&events->pmu_lock);
-		events->percpu_pmu = cpu_pmu;
-	}
-
-	cpu_pmu->hw_events	= cpu_hw_events;
-	cpu_pmu->request_irq	= cpu_pmu_request_irq;
-	cpu_pmu->free_irq	= cpu_pmu_free_irq;
-
-	/* Ensure the PMU has sane values out of reset. */
-	if (cpu_pmu->reset)
-		on_each_cpu_mask(&cpu_pmu->supported_cpus, cpu_pmu->reset,
-			 cpu_pmu, 1);
-
-	/* If no interrupts available, set the corresponding capability flag */
-	if (!platform_get_irq(cpu_pmu->plat_device, 0))
-		cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
-
-	/*
-	 * This is a CPU PMU potentially in a heterogeneous configuration (e.g.
-	 * big.LITTLE). This is not an uncore PMU, and we have taken ctx
-	 * sharing into account (e.g. with our pmu::filter_match callback and
-	 * pmu::event_init group validation).
-	 */
-	cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_HETEROGENEOUS_CPUS;
 
 	return 0;
 
 out_unregister:
 	cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_STARTING,
 					    &cpu_pmu->node);
-out_free:
-	free_percpu(cpu_hw_events);
+out:
 	return err;
 }
 
···
 	cpu_pm_pmu_unregister(cpu_pmu);
 	cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_STARTING,
 					    &cpu_pmu->node);
-	free_percpu(cpu_pmu->hw_events);
 }
 
-/*
- * CPU PMU identification and probing.
- */
-static int probe_current_pmu(struct arm_pmu *pmu,
-			     const struct pmu_probe_info *info)
+struct arm_pmu *armpmu_alloc(void)
 {
-	int cpu = get_cpu();
-	unsigned int cpuid = read_cpuid_id();
-	int ret = -ENODEV;
-
-	pr_info("probing PMU on CPU %d\n", cpu);
-
-	for (; info->init != NULL; info++) {
-		if ((cpuid & info->mask) != info->cpuid)
-			continue;
-		ret = info->init(pmu);
-		break;
-	}
-
-	put_cpu();
-	return ret;
-}
-
-static int of_pmu_irq_cfg(struct arm_pmu *pmu)
-{
-	int *irqs, i = 0;
-	bool using_spi = false;
-	struct platform_device *pdev = pmu->plat_device;
-
-	irqs = kcalloc(pdev->num_resources, sizeof(*irqs), GFP_KERNEL);
-	if (!irqs)
-		return -ENOMEM;
-
-	do {
-		struct device_node *dn;
-		int cpu, irq;
-
-		/* See if we have an affinity entry */
-		dn = of_parse_phandle(pdev->dev.of_node, "interrupt-affinity", i);
-		if (!dn)
-			break;
-
-		/* Check the IRQ type and prohibit a mix of PPIs and SPIs */
-		irq = platform_get_irq(pdev, i);
-		if (irq > 0) {
-			bool spi = !irq_is_percpu(irq);
-
-			if (i > 0 && spi != using_spi) {
-				pr_err("PPI/SPI IRQ type mismatch for %s!\n",
-					dn->name);
-				of_node_put(dn);
-				kfree(irqs);
-				return -EINVAL;
-			}
-
-			using_spi = spi;
-		}
-
-		/* Now look up the logical CPU number */
-		for_each_possible_cpu(cpu) {
-			struct device_node *cpu_dn;
-
-			cpu_dn = of_cpu_device_node_get(cpu);
-			of_node_put(cpu_dn);
-
-			if (dn == cpu_dn)
-				break;
-		}
-
-		if (cpu >= nr_cpu_ids) {
-			pr_warn("Failed to find logical CPU for %s\n",
-				dn->name);
-			of_node_put(dn);
-			cpumask_setall(&pmu->supported_cpus);
-			break;
-		}
-		of_node_put(dn);
-
-		/* For SPIs, we need to track the affinity per IRQ */
-		if (using_spi) {
-			if (i >= pdev->num_resources)
-				break;
-
-			irqs[i] = cpu;
-		}
-
-		/* Keep track of the CPUs containing this PMU type */
-		cpumask_set_cpu(cpu, &pmu->supported_cpus);
-		i++;
-	} while (1);
-
-	/* If we didn't manage to parse anything, try the interrupt affinity */
-	if (cpumask_weight(&pmu->supported_cpus) == 0) {
-		int irq = platform_get_irq(pdev, 0);
-
-		if (irq > 0 && irq_is_percpu(irq)) {
-			/* If using PPIs, check the affinity of the partition */
-			int ret;
-
-			ret = irq_get_percpu_devid_partition(irq, &pmu->supported_cpus);
-			if (ret) {
-				kfree(irqs);
-				return ret;
-			}
-		} else {
-			/* Otherwise default to all CPUs */
-			cpumask_setall(&pmu->supported_cpus);
-		}
-	}
-
-	/* If we matched up the IRQ affinities, use them to route the SPIs */
-	if (using_spi && i == pdev->num_resources)
-		pmu->irq_affinity = irqs;
-	else
-		kfree(irqs);
-
-	return 0;
-}
-
-int arm_pmu_device_probe(struct platform_device *pdev,
-			 const struct of_device_id *of_table,
-			 const struct pmu_probe_info *probe_table)
-{
-	const struct of_device_id *of_id;
-	const int (*init_fn)(struct arm_pmu *);
-	struct device_node *node = pdev->dev.of_node;
 	struct arm_pmu *pmu;
-	int ret = -ENODEV;
+	int cpu;
 
-	pmu = kzalloc(sizeof(struct arm_pmu), GFP_KERNEL);
+	pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
 	if (!pmu) {
 		pr_info("failed to allocate PMU device!\n");
-		return -ENOMEM;
+		goto out;
 	}
 
-	armpmu_init(pmu);
-
-	pmu->plat_device = pdev;
-
-	if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
-		init_fn = of_id->data;
-
-		pmu->secure_access = of_property_read_bool(pdev->dev.of_node,
-							   "secure-reg-access");
-
-		/* arm64 systems boot only as non-secure */
-		if (IS_ENABLED(CONFIG_ARM64) && pmu->secure_access) {
-			pr_warn("ignoring \"secure-reg-access\" property for arm64\n");
-			pmu->secure_access = false;
-		}
-
-		ret = of_pmu_irq_cfg(pmu);
-		if (!ret)
-			ret = init_fn(pmu);
-	} else if (probe_table) {
-		cpumask_setall(&pmu->supported_cpus);
-		ret = probe_current_pmu(pmu, probe_table);
+	pmu->hw_events = alloc_percpu(struct pmu_hw_events);
+	if (!pmu->hw_events) {
+		pr_info("failed to allocate per-cpu PMU data.\n");
+		goto out_free_pmu;
 	}
 
-	if (ret) {
-		pr_info("%s: failed to probe PMU!\n", of_node_full_name(node));
-		goto out_free;
+	pmu->pmu = (struct pmu) {
+		.pmu_enable	= armpmu_enable,
+		.pmu_disable	= armpmu_disable,
+		.event_init	= armpmu_event_init,
+		.add		= armpmu_add,
+		.del		= armpmu_del,
+		.start		= armpmu_start,
+		.stop		= armpmu_stop,
+		.read		= armpmu_read,
+		.filter_match	= armpmu_filter_match,
+		.attr_groups	= pmu->attr_groups,
+		/*
+		 * This is a CPU PMU potentially in a heterogeneous
+		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
+		 * and we have taken ctx sharing into account (e.g. with our
+		 * pmu::filter_match callback and pmu::event_init group
+		 * validation).
+		 */
+		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS,
+	};
+
+	pmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =
+		&armpmu_common_attr_group;
+
+	for_each_possible_cpu(cpu) {
+		struct pmu_hw_events *events;
+
+		events = per_cpu_ptr(pmu->hw_events, cpu);
+		raw_spin_lock_init(&events->pmu_lock);
+		events->percpu_pmu = pmu;
 	}
 
+	return pmu;
+
+out_free_pmu:
+	kfree(pmu);
+out:
+	return NULL;
+}
+
+void armpmu_free(struct arm_pmu *pmu)
+{
+	free_percpu(pmu->hw_events);
+	kfree(pmu);
+}
+
+int armpmu_register(struct arm_pmu *pmu)
+{
+	int ret;
 
 	ret = cpu_pmu_init(pmu);
 	if (ret)
-		goto out_free;
+		return ret;
 
 	ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
 	if (ret)
···
 		__oprofile_cpu_pmu = pmu;
 
 	pr_info("enabled with %s PMU driver, %d counters available\n",
-			pmu->name, pmu->num_events);
+		pmu->name, pmu->num_events);
 
 	return 0;
 
 out_destroy:
 	cpu_pmu_destroy(pmu);
-out_free:
-	pr_info("%s: failed to register PMU devices!\n",
-		of_node_full_name(node));
-	kfree(pmu->irq_affinity);
-	kfree(pmu);
 	return ret;
 }
 
···
 
 	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_STARTING,
 				      "perf/arm/pmu:starting",
-				      arm_perf_starting_cpu, NULL);
+				      arm_perf_starting_cpu,
+				      arm_perf_teardown_cpu);
 	if (ret)
 		pr_err("CPU hotplug notifier for ARM PMU could not be registered: %d\n",
 		       ret);

drivers/perf/arm_pmu_acpi.c

···
+/*
+ * ACPI probing code for ARM performance counters.
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ *
+ * 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/acpi.h>
+#include <linux/cpumask.h>
+#include <linux/init.h>
+#include <linux/percpu.h>
+#include <linux/perf/arm_pmu.h>
+
+#include <asm/cputype.h>
+
+static DEFINE_PER_CPU(struct arm_pmu *, probed_pmus);
+static DEFINE_PER_CPU(int, pmu_irqs);
+
+static int arm_pmu_acpi_register_irq(int cpu)
+{
+	struct acpi_madt_generic_interrupt *gicc;
+	int gsi, trigger;
+
+	gicc = acpi_cpu_get_madt_gicc(cpu);
+	if (WARN_ON(!gicc))
+		return -EINVAL;
+
+	gsi = gicc->performance_interrupt;
+	if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
+		trigger = ACPI_EDGE_SENSITIVE;
+	else
+		trigger = ACPI_LEVEL_SENSITIVE;
+
+	/*
+	 * Helpfully, the MADT GICC doesn't have a polarity flag for the
+	 * "performance interrupt". Luckily, on compliant GICs the polarity is
+	 * a fixed value in HW (for both SPIs and PPIs) that we cannot change
+	 * from SW.
+	 *
+	 * Here we pass in ACPI_ACTIVE_HIGH to keep the core code happy. This
+	 * may not match the real polarity, but that should not matter.
+	 *
+	 * Other interrupt controllers are not supported with ACPI.
+	 */
+	return acpi_register_gsi(NULL, gsi, trigger, ACPI_ACTIVE_HIGH);
+}
+
+static void arm_pmu_acpi_unregister_irq(int cpu)
+{
+	struct acpi_madt_generic_interrupt *gicc;
+	int gsi;
+
+	gicc = acpi_cpu_get_madt_gicc(cpu);
+	if (!gicc)
+		return;
+
+	gsi = gicc->performance_interrupt;
+	acpi_unregister_gsi(gsi);
+}
+
+static int arm_pmu_acpi_parse_irqs(void)
+{
+	int irq, cpu, irq_cpu, err;
+
+	for_each_possible_cpu(cpu) {
+		irq = arm_pmu_acpi_register_irq(cpu);
+		if (irq < 0) {
+			err = irq;
+			pr_warn("Unable to parse ACPI PMU IRQ for CPU%d: %d\n",
+				cpu, err);
+			goto out_err;
+		} else if (irq == 0) {
+			pr_warn("No ACPI PMU IRQ for CPU%d\n", cpu);
+		}
+
+		per_cpu(pmu_irqs, cpu) = irq;
+	}
+
+	return 0;
+
+out_err:
+	for_each_possible_cpu(cpu) {
+		irq = per_cpu(pmu_irqs, cpu);
+		if (!irq)
+			continue;
+
+		arm_pmu_acpi_unregister_irq(cpu);
+
+		/*
+		 * Blat all copies of the IRQ so that we only unregister the
+		 * corresponding GSI once (e.g. when we have PPIs).
+		 */
+		for_each_possible_cpu(irq_cpu) {
+			if (per_cpu(pmu_irqs, irq_cpu) == irq)
+				per_cpu(pmu_irqs, irq_cpu) = 0;
+		}
+	}
+
+	return err;
+}
+
+static struct arm_pmu *arm_pmu_acpi_find_alloc_pmu(void)
+{
+	unsigned long cpuid = read_cpuid_id();
+	struct arm_pmu *pmu;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		pmu = per_cpu(probed_pmus, cpu);
+		if (!pmu || pmu->acpi_cpuid != cpuid)
+			continue;
+
+		return pmu;
+	}
+
+	pmu = armpmu_alloc();
+	if (!pmu) {
+		pr_warn("Unable to allocate PMU for CPU%d\n",
+			smp_processor_id());
+		return NULL;
+	}
+
+	pmu->acpi_cpuid = cpuid;
+
+	return pmu;
+}
+
+/*
+ * This must run before the common arm_pmu hotplug logic, so that we can
+ * associate a CPU and its interrupt before the common code tries to manage the
+ * affinity and so on.
+ *
+ * Note that hotplug events are serialized, so we cannot race with another CPU
+ * coming up. The perf core won't open events while a hotplug event is in
+ * progress.
+ */
+static int arm_pmu_acpi_cpu_starting(unsigned int cpu)
+{
+	struct arm_pmu *pmu;
+	struct pmu_hw_events __percpu *hw_events;
+	int irq;
+
+	/* If we've already probed this CPU, we have nothing to do */
+	if (per_cpu(probed_pmus, cpu))
+		return 0;
+
+	irq = per_cpu(pmu_irqs, cpu);
+
+	pmu = arm_pmu_acpi_find_alloc_pmu();
+	if (!pmu)
+		return -ENOMEM;
+
+	cpumask_set_cpu(cpu, &pmu->supported_cpus);
+
+	per_cpu(probed_pmus, cpu) = pmu;
+
+	/*
+	 * Log and request the IRQ so the core arm_pmu code can manage it.  In
+	 * some situations (e.g. mismatched PPIs), we may fail to request the
+	 * IRQ. However, it may be too late for us to do anything about it.
+	 * The common ARM PMU code will log a warning in this case.
+	 */
+	hw_events = pmu->hw_events;
+	per_cpu(hw_events->irq, cpu) = irq;
+	armpmu_request_irq(pmu, cpu);
+
+	/*
+	 * Ideally, we'd probe the PMU here when we find the first matching
+	 * CPU. We can't do that for several reasons; see the comment in
+	 * arm_pmu_acpi_init().
+	 *
+	 * So for the time being, we're done.
+	 */
+	return 0;
+}
+
+int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
+{
+	int pmu_idx = 0;
+	int cpu, ret;
+
+	if (acpi_disabled)
+		return 0;
+
+	/*
+	 * Initialise and register the set of PMUs which we know about right
+	 * now. Ideally we'd do this in arm_pmu_acpi_cpu_starting() so that we
+	 * could handle late hotplug, but this may lead to deadlock since we
+	 * might try to register a hotplug notifier instance from within a
+	 * hotplug notifier.
+	 *
+	 * There's also the problem of having access to the right init_fn,
+	 * without tying this too deeply into the "real" PMU driver.
+	 *
+	 * For the moment, as with the platform/DT case, we need at least one
+	 * of a PMU's CPUs to be online at probe time.
+	 */
+	for_each_possible_cpu(cpu) {
+		struct arm_pmu *pmu = per_cpu(probed_pmus, cpu);
+		char *base_name;
+
+		if (!pmu || pmu->name)
+			continue;
+
+		ret = init_fn(pmu);
+		if (ret == -ENODEV) {
+			/* PMU not handled by this driver, or not present */
+			continue;
+		} else if (ret) {
+			pr_warn("Unable to initialise PMU for CPU%d\n", cpu);
+			return ret;
+		}
+
+		base_name = pmu->name;
+		pmu->name = kasprintf(GFP_KERNEL, "%s_%d", base_name, pmu_idx++);
+		if (!pmu->name) {
+			pr_warn("Unable to allocate PMU name for CPU%d\n", cpu);
+			return -ENOMEM;
+		}
+
+		ret = armpmu_register(pmu);
+		if (ret) {
+			pr_warn("Failed to register PMU for CPU%d\n", cpu);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int arm_pmu_acpi_init(void)
+{
+	int ret;
+
+	if (acpi_disabled)
+		return 0;
+
+	/*
+	 * We can't request IRQs yet, since we don't know the cookie value
+	 * until we know which CPUs share the same logical PMU. We'll handle
+	 * that in arm_pmu_acpi_cpu_starting().
+	 */
+	ret = arm_pmu_acpi_parse_irqs();
+	if (ret)
+		return ret;
+
+	ret = cpuhp_setup_state(CPUHP_AP_PERF_ARM_ACPI_STARTING,
+				"perf/arm/pmu_acpi:starting",
+				arm_pmu_acpi_cpu_starting, NULL);
+
+	return ret;
+}
+subsys_initcall(arm_pmu_acpi_init)

drivers/perf/arm_pmu_platform.c

···
+/*
+ * platform_device probing code for ARM performance counters.
+ *
+ * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
+ * Copyright (C) 2010 ARM Ltd., Will Deacon <[e-mail]>
+ */
+#define pr_fmt(fmt) "hw perfevents: " fmt
+
+#include <linux/bug.h>
+#include <linux/cpumask.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/kconfig.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/percpu.h>
+#include <linux/perf/arm_pmu.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+
+static int probe_current_pmu(struct arm_pmu *pmu,
+			     const struct pmu_probe_info *info)
+{
+	int cpu = get_cpu();
+	unsigned int cpuid = read_cpuid_id();
+	int ret = -ENODEV;
+
+	pr_info("probing PMU on CPU %d\n", cpu);
+
+	for (; info->init != NULL; info++) {
+		if ((cpuid & info->mask) != info->cpuid)
+			continue;
+		ret = info->init(pmu);
+		break;
+	}
+
+	put_cpu();
+	return ret;
+}
+
+static int pmu_parse_percpu_irq(struct arm_pmu *pmu, int irq)
+{
+	int cpu, ret;
+	struct pmu_hw_events __percpu *hw_events = pmu->hw_events;
+
+	ret = irq_get_percpu_devid_partition(irq, &pmu->supported_cpus);
+	if (ret)
+		return ret;
+
+	for_each_cpu(cpu, &pmu->supported_cpus)
+		per_cpu(hw_events->irq, cpu) = irq;
+
+	return 0;
+}
+
+static bool pmu_has_irq_affinity(struct device_node *node)
+{
+	return !!of_find_property(node, "interrupt-affinity", NULL);
+}
+
+static int pmu_parse_irq_affinity(struct device_node *node, int i)
+{
+	struct device_node *dn;
+	int cpu;
+
+	/*
+	 * If we don't have an interrupt-affinity property, we guess irq
+	 * affinity matches our logical CPU order, as we used to assume.
+	 * This is fragile, so we'll warn in pmu_parse_irqs().
+	 */
+	if (!pmu_has_irq_affinity(node))
+		return i;
+
+	dn = of_parse_phandle(node, "interrupt-affinity", i);
+	if (!dn) {
+		pr_warn("failed to parse interrupt-affinity[%d] for %s\n",
+			i, node->name);
+		return -EINVAL;
+	}
+
+	/* Now look up the logical CPU number */
+	for_each_possible_cpu(cpu) {
+		struct device_node *cpu_dn;
+
+		cpu_dn = of_cpu_device_node_get(cpu);
+		of_node_put(cpu_dn);
+
+		if (dn == cpu_dn)
+			break;
+	}
+
+	if (cpu >= nr_cpu_ids) {
+		pr_warn("failed to find logical CPU for %s\n", dn->name);
+	}
+
+	of_node_put(dn);
+
+	return cpu;
+}
+
+static int pmu_parse_irqs(struct arm_pmu *pmu)
+{
+	int i = 0, num_irqs;
+	struct platform_device *pdev = pmu->plat_device;
+	struct pmu_hw_events __percpu *hw_events = pmu->hw_events;
+
+	num_irqs = platform_irq_count(pdev);
+	if (num_irqs < 0) {
+		pr_err("unable to count PMU IRQs\n");
+		return num_irqs;
+	}
+
+	/*
+	 * In this case we have no idea which CPUs are covered by the PMU.
+	 * To match our prior behaviour, we assume all CPUs in this case.
+	 */
+	if (num_irqs == 0) {
+		pr_warn("no irqs for PMU, sampling events not supported\n");
+		pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+		cpumask_setall(&pmu->supported_cpus);
+		return 0;
+	}
+
+	if (num_irqs == 1) {
+		int irq = platform_get_irq(pdev, 0);
+		if (irq && irq_is_percpu(irq))
+			return pmu_parse_percpu_irq(pmu, irq);
+	}
+
+	if (!pmu_has_irq_affinity(pdev->dev.of_node)) {
+		pr_warn("no interrupt-affinity property for %s, guessing.\n",
+			of_node_full_name(pdev->dev.of_node));
+	}
+
+	/*
+	 * Some platforms have all PMU IRQs OR'd into a single IRQ, with a
+	 * special platdata function that attempts to demux them.
+	 */
+	if (dev_get_platdata(&pdev->dev))
+		cpumask_setall(&pmu->supported_cpus);
+
+	for (i = 0; i < num_irqs; i++) {
+		int cpu, irq;
+
+		irq = platform_get_irq(pdev, i);
+		if (WARN_ON(irq <= 0))
+			continue;
+
+		if (irq_is_percpu(irq)) {
+			pr_warn("multiple PPIs or mismatched SPI/PPI detected\n");
+			return -EINVAL;
+		}
+
+		cpu = pmu_parse_irq_affinity(pdev->dev.of_node, i);
+		if (cpu < 0)
+			return cpu;
+		if (cpu >= nr_cpu_ids)
+			continue;
+
+		if (per_cpu(hw_events->irq, cpu)) {
+			pr_warn("multiple PMU IRQs for the same CPU detected\n");
+			return -EINVAL;
+		}
+
+		per_cpu(hw_events->irq, cpu) = irq;
+		cpumask_set_cpu(cpu, &pmu->supported_cpus);
+	}
+
+	return 0;
+}
+
+int arm_pmu_device_probe(struct platform_device *pdev,
+			 const struct of_device_id *of_table,
+			 const struct pmu_probe_info *probe_table)
+{
+	const struct of_device_id *of_id;
+	armpmu_init_fn init_fn;
+	struct device_node *node = pdev->dev.of_node;
+	struct arm_pmu *pmu;
+	int ret = -ENODEV;
+
+	pmu = armpmu_alloc();
+	if (!pmu)
+		return -ENOMEM;
+
+	pmu->plat_device = pdev;
+
+	ret = pmu_parse_irqs(pmu);
+	if (ret)
+		goto out_free;
+
+	if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
+		init_fn = of_id->data;
+
+		pmu->secure_access = of_property_read_bool(pdev->dev.of_node,
+							   "secure-reg-access");
+
+		/* arm64 systems boot only as non-secure */
+		if (IS_ENABLED(CONFIG_ARM64) && pmu->secure_access) {
+			pr_warn("ignoring \"secure-reg-access\" property for arm64\n");
+			pmu->secure_access = false;
+		}
+
+		ret = init_fn(pmu);
+	} else if (probe_table) {
+		cpumask_setall(&pmu->supported_cpus);
+		ret = probe_current_pmu(pmu, probe_table);
+	}
+
+	if (ret) {
+		pr_info("%s: failed to probe PMU!\n", of_node_full_name(node));
+		goto out_free;
+	}
+
+	ret = armpmu_request_irqs(pmu);
+	if (ret)
+		goto out_free_irqs;
+
+	ret = armpmu_register(pmu);
+	if (ret)
+		goto out_free;
+
+	return 0;
+
+out_free_irqs:
+	armpmu_free_irqs(pmu);
+out_free:
+	pr_info("%s: failed to register PMU devices!\n",
+		of_node_full_name(node));
+	armpmu_free(pmu);
+	return ret;
+}

drivers/perf/qcom_l3_pmu.c

···
+/*
+ * Driver for the L3 cache PMUs in Qualcomm Technologies chips.
+ *
+ * The driver supports a distributed cache architecture where the overall
+ * cache for a socket is comprised of multiple slices each with its own PMU.
+ * Access to each individual PMU is provided even though all CPUs share all
+ * the slices. User space needs to aggregate to individual counts to provide
+ * a global picture.
+ *
+ * See Documentation/perf/qcom_l3_pmu.txt for more details.
+ *
+ * Copyright (c) 2015-2017, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/perf_event.h>
+#include <linux/platform_device.h>
+
+/*
+ * General constants
+ */
+
+/* Number of counters on each PMU */
+#define L3_NUM_COUNTERS  8
+/* Mask for the event type field within perf_event_attr.config and EVTYPE reg */
+#define L3_EVTYPE_MASK   0xFF
+/*
+ * Bit position of the 'long counter' flag within perf_event_attr.config.
+ * Reserve some space between the event type and this flag to allow expansion
+ * in the event type field.
+ */
+#define L3_EVENT_LC_BIT  32
+
+/*
+ * Register offsets
+ */
+
+/* Perfmon registers */
+#define L3_HML3_PM_CR       0x000
+#define L3_HML3_PM_EVCNTR(__cntr) (0x420 + ((__cntr) & 0x7) * 8)
+#define L3_HML3_PM_CNTCTL(__cntr) (0x120 + ((__cntr) & 0x7) * 8)
+#define L3_HML3_PM_EVTYPE(__cntr) (0x220 + ((__cntr) & 0x7) * 8)
+#define L3_HML3_PM_FILTRA   0x300
+#define L3_HML3_PM_FILTRB   0x308
+#define L3_HML3_PM_FILTRC   0x310
+#define L3_HML3_PM_FILTRAM  0x304
+#define L3_HML3_PM_FILTRBM  0x30C
+#define L3_HML3_PM_FILTRCM  0x314
+
+/* Basic counter registers */
+#define L3_M_BC_CR         0x500
+#define L3_M_BC_SATROLL_CR 0x504
+#define L3_M_BC_CNTENSET   0x508
+#define L3_M_BC_CNTENCLR   0x50C
+#define L3_M_BC_INTENSET   0x510
+#define L3_M_BC_INTENCLR   0x514
+#define L3_M_BC_GANG       0x718
+#define L3_M_BC_OVSR       0x740
+#define L3_M_BC_IRQCTL     0x96C
+
+/*
+ * Bit field definitions
+ */
+
+/* L3_HML3_PM_CR */
+#define PM_CR_RESET           (0)
+
+/* L3_HML3_PM_XCNTCTL/L3_HML3_PM_CNTCTLx */
+#define PMCNT_RESET           (0)
+
+/* L3_HML3_PM_EVTYPEx */
+#define EVSEL(__val)          ((__val) & L3_EVTYPE_MASK)
+
+/* Reset value for all the filter registers */
+#define PM_FLTR_RESET         (0)
+
+/* L3_M_BC_CR */
+#define BC_RESET              (1UL << 1)
+#define BC_ENABLE             (1UL << 0)
+
+/* L3_M_BC_SATROLL_CR */
+#define BC_SATROLL_CR_RESET   (0)
+
+/* L3_M_BC_CNTENSET */
+#define PMCNTENSET(__cntr)    (1UL << ((__cntr) & 0x7))
+
+/* L3_M_BC_CNTENCLR */
+#define PMCNTENCLR(__cntr)    (1UL << ((__cntr) & 0x7))
+#define BC_CNTENCLR_RESET     (0xFF)
+
+/* L3_M_BC_INTENSET */
+#define PMINTENSET(__cntr)    (1UL << ((__cntr) & 0x7))
+
+/* L3_M_BC_INTENCLR */
+#define PMINTENCLR(__cntr)    (1UL << ((__cntr) & 0x7))
+#define BC_INTENCLR_RESET     (0xFF)
+
+/* L3_M_BC_GANG */
+#define GANG_EN(__cntr)       (1UL << ((__cntr) & 0x7))
+#define BC_GANG_RESET         (0)
+
+/* L3_M_BC_OVSR */
+#define PMOVSRCLR(__cntr)     (1UL << ((__cntr) & 0x7))
+#define PMOVSRCLR_RESET       (0xFF)
+
+/* L3_M_BC_IRQCTL */
+#define PMIRQONMSBEN(__cntr)  (1UL << ((__cntr) & 0x7))
+#define BC_IRQCTL_RESET       (0x0)
+
+/*
+ * Events
+ */
+
+#define L3_EVENT_CYCLES		0x01
+#define L3_EVENT_READ_HIT		0x20
+#define L3_EVENT_READ_MISS		0x21
+#define L3_EVENT_READ_HIT_D		0x22
+#define L3_EVENT_READ_MISS_D		0x23
+#define L3_EVENT_WRITE_HIT		0x24
+#define L3_EVENT_WRITE_MISS		0x25
+
+/*
+ * Decoding of settings from perf_event_attr
+ *
+ * The config format for perf events is:
+ * - config: bits 0-7: event type
+ *           bit  32:  HW counter size requested, 0: 32 bits, 1: 64 bits
+ */
+
+static inline u32 get_event_type(struct perf_event *event)
+{
+	return (event->attr.config) & L3_EVTYPE_MASK;
+}
+
+static inline bool event_uses_long_counter(struct perf_event *event)
+{
+	return !!(event->attr.config & BIT_ULL(L3_EVENT_LC_BIT));
+}
+
+static inline int event_num_counters(struct perf_event *event)
+{
+	return event_uses_long_counter(event) ? 2 : 1;
+}
+
+/*
+ * Main PMU, inherits from the core perf PMU type
+ */
+struct l3cache_pmu {
+	struct pmu		pmu;
+	struct hlist_node	node;
+	void __iomem		*regs;
+	struct perf_event	*events[L3_NUM_COUNTERS];
+	unsigned long		used_mask[BITS_TO_LONGS(L3_NUM_COUNTERS)];
+	cpumask_t		cpumask;
+};
+
+#define to_l3cache_pmu(p) (container_of(p, struct l3cache_pmu, pmu))
+
+/*
+ * Type used to group hardware counter operations
+ *
+ * Used to implement two types of hardware counters, standard (32bits) and
+ * long (64bits). The hardware supports counter chaining which we use to
+ * implement long counters. This support is exposed via the 'lc' flag field
+ * in perf_event_attr.config.
+ */
+struct l3cache_event_ops {
+	/* Called to start event monitoring */
+	void (*start)(struct perf_event *event);
+	/* Called to stop event monitoring */
+	void (*stop)(struct perf_event *event, int flags);
+	/* Called to update the perf_event */
+	void (*update)(struct perf_event *event);
+};
+
+/*
+ * Implementation of long counter operations
+ *
+ * 64bit counters are implemented by chaining two of the 32bit physical
+ * counters. The PMU only supports chaining of adjacent even/odd pairs
+ * and for simplicity the driver always configures the odd counter to
+ * count the overflows of the lower-numbered even counter. Note that since
+ * the resulting hardware counter is 64bits no IRQs are required to maintain
+ * the software counter which is also 64bits.
+ */
+
+static void qcom_l3_cache__64bit_counter_start(struct perf_event *event)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 evsel = get_event_type(event);
+	u32 gang;
+
+	/* Set the odd counter to count the overflows of the even counter */
+	gang = readl_relaxed(l3pmu->regs + L3_M_BC_GANG);
+	gang |= GANG_EN(idx + 1);
+	writel_relaxed(gang, l3pmu->regs + L3_M_BC_GANG);
+
+	/* Initialize the hardware counters and reset prev_count*/
+	local64_set(&event->hw.prev_count, 0);
+	writel_relaxed(0, l3pmu->regs + L3_HML3_PM_EVCNTR(idx + 1));
+	writel_relaxed(0, l3pmu->regs + L3_HML3_PM_EVCNTR(idx));
+
+	/*
+	 * Set the event types, the upper half must use zero and the lower
+	 * half the actual event type
+	 */
+	writel_relaxed(EVSEL(0), l3pmu->regs + L3_HML3_PM_EVTYPE(idx + 1));
+	writel_relaxed(EVSEL(evsel), l3pmu->regs + L3_HML3_PM_EVTYPE(idx));
+
+	/* Finally, enable the counters */
+	writel_relaxed(PMCNT_RESET, l3pmu->regs + L3_HML3_PM_CNTCTL(idx + 1));
+	writel_relaxed(PMCNTENSET(idx + 1), l3pmu->regs + L3_M_BC_CNTENSET);
+	writel_relaxed(PMCNT_RESET, l3pmu->regs + L3_HML3_PM_CNTCTL(idx));
+	writel_relaxed(PMCNTENSET(idx), l3pmu->regs + L3_M_BC_CNTENSET);
+}
+
+static void qcom_l3_cache__64bit_counter_stop(struct perf_event *event,
+					      int flags)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 gang = readl_relaxed(l3pmu->regs + L3_M_BC_GANG);
+
+	/* Disable the counters */
+	writel_relaxed(PMCNTENCLR(idx), l3pmu->regs + L3_M_BC_CNTENCLR);
+	writel_relaxed(PMCNTENCLR(idx + 1), l3pmu->regs + L3_M_BC_CNTENCLR);
+
+	/* Disable chaining */
+	writel_relaxed(gang & ~GANG_EN(idx + 1), l3pmu->regs + L3_M_BC_GANG);
+}
+
+static void qcom_l3_cache__64bit_counter_update(struct perf_event *event)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 hi, lo;
+	u64 prev, new;
+
+	do {
+		prev = local64_read(&event->hw.prev_count);
+		do {
+			hi = readl_relaxed(l3pmu->regs + L3_HML3_PM_EVCNTR(idx + 1));
+			lo = readl_relaxed(l3pmu->regs + L3_HML3_PM_EVCNTR(idx));
+		} while (hi != readl_relaxed(l3pmu->regs + L3_HML3_PM_EVCNTR(idx + 1)));
+		new = ((u64)hi << 32) | lo;
+	} while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);
+
+	local64_add(new - prev, &event->count);
+}
+
+static const struct l3cache_event_ops event_ops_long = {
+	.start = qcom_l3_cache__64bit_counter_start,
+	.stop = qcom_l3_cache__64bit_counter_stop,
+	.update = qcom_l3_cache__64bit_counter_update,
+};
+
+/*
+ * Implementation of standard counter operations
+ *
+ * 32bit counters use a single physical counter and a hardware feature that
+ * asserts the overflow IRQ on the toggling of the most significant bit in
+ * the counter. This feature allows the counters to be left free-running
+ * without needing the usual reprogramming required to properly handle races
+ * during concurrent calls to update.
+ */
+
+static void qcom_l3_cache__32bit_counter_start(struct perf_event *event)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 evsel = get_event_type(event);
+	u32 irqctl = readl_relaxed(l3pmu->regs + L3_M_BC_IRQCTL);
+
+	/* Set the counter to assert the overflow IRQ on MSB toggling */
+	writel_relaxed(irqctl | PMIRQONMSBEN(idx), l3pmu->regs + L3_M_BC_IRQCTL);
+
+	/* Initialize the hardware counter and reset prev_count*/
+	local64_set(&event->hw.prev_count, 0);
+	writel_relaxed(0, l3pmu->regs + L3_HML3_PM_EVCNTR(idx));
+
+	/* Set the event type */
+	writel_relaxed(EVSEL(evsel), l3pmu->regs + L3_HML3_PM_EVTYPE(idx));
+
+	/* Enable interrupt generation by this counter */
+	writel_relaxed(PMINTENSET(idx), l3pmu->regs + L3_M_BC_INTENSET);
+
+	/* Finally, enable the counter */
+	writel_relaxed(PMCNT_RESET, l3pmu->regs + L3_HML3_PM_CNTCTL(idx));
+	writel_relaxed(PMCNTENSET(idx), l3pmu->regs + L3_M_BC_CNTENSET);
+}
+
+static void qcom_l3_cache__32bit_counter_stop(struct perf_event *event,
+					      int flags)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 irqctl = readl_relaxed(l3pmu->regs + L3_M_BC_IRQCTL);
+
+	/* Disable the counter */
+	writel_relaxed(PMCNTENCLR(idx), l3pmu->regs + L3_M_BC_CNTENCLR);
+
+	/* Disable interrupt generation by this counter */
+	writel_relaxed(PMINTENCLR(idx), l3pmu->regs + L3_M_BC_INTENCLR);
+
+	/* Set the counter to not assert the overflow IRQ on MSB toggling */
+	writel_relaxed(irqctl & ~PMIRQONMSBEN(idx), l3pmu->regs + L3_M_BC_IRQCTL);
+}
+
+static void qcom_l3_cache__32bit_counter_update(struct perf_event *event)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	int idx = event->hw.idx;
+	u32 prev, new;
+
+	do {
+		prev = local64_read(&event->hw.prev_count);
+		new = readl_relaxed(l3pmu->regs + L3_HML3_PM_EVCNTR(idx));
+	} while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);
+
+	local64_add(new - prev, &event->count);
+}
+
+static const struct l3cache_event_ops event_ops_std = {
+	.start = qcom_l3_cache__32bit_counter_start,
+	.stop = qcom_l3_cache__32bit_counter_stop,
+	.update = qcom_l3_cache__32bit_counter_update,
+};
+
+/* Retrieve the appropriate operations for the given event */
+static
+const struct l3cache_event_ops *l3cache_event_get_ops(struct perf_event *event)
+{
+	if (event_uses_long_counter(event))
+		return &event_ops_long;
+	else
+		return &event_ops_std;
+}
+
+/*
+ * Top level PMU functions.
+ */
+
+static inline void qcom_l3_cache__init(struct l3cache_pmu *l3pmu)
+{
+	int i;
+
+	writel_relaxed(BC_RESET, l3pmu->regs + L3_M_BC_CR);
+
+	/*
+	 * Use writel for the first programming command to ensure the basic
+	 * counter unit is stopped before proceeding
+	 */
+	writel(BC_SATROLL_CR_RESET, l3pmu->regs + L3_M_BC_SATROLL_CR);
+
+	writel_relaxed(BC_CNTENCLR_RESET, l3pmu->regs + L3_M_BC_CNTENCLR);
+	writel_relaxed(BC_INTENCLR_RESET, l3pmu->regs + L3_M_BC_INTENCLR);
+	writel_relaxed(PMOVSRCLR_RESET, l3pmu->regs + L3_M_BC_OVSR);
+	writel_relaxed(BC_GANG_RESET, l3pmu->regs + L3_M_BC_GANG);
+	writel_relaxed(BC_IRQCTL_RESET, l3pmu->regs + L3_M_BC_IRQCTL);
+	writel_relaxed(PM_CR_RESET, l3pmu->regs + L3_HML3_PM_CR);
+
+	for (i = 0; i < L3_NUM_COUNTERS; ++i) {
+		writel_relaxed(PMCNT_RESET, l3pmu->regs + L3_HML3_PM_CNTCTL(i));
+		writel_relaxed(EVSEL(0), l3pmu->regs + L3_HML3_PM_EVTYPE(i));
+	}
+
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRA);
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRAM);
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRB);
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRBM);
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRC);
+	writel_relaxed(PM_FLTR_RESET, l3pmu->regs + L3_HML3_PM_FILTRCM);
+
+	/*
+	 * Use writel here to ensure all programming commands are done
+	 *  before proceeding
+	 */
+	writel(BC_ENABLE, l3pmu->regs + L3_M_BC_CR);
+}
+
+static irqreturn_t qcom_l3_cache__handle_irq(int irq_num, void *data)
+{
+	struct l3cache_pmu *l3pmu = data;
+	/* Read the overflow status register */
+	long status = readl_relaxed(l3pmu->regs + L3_M_BC_OVSR);
+	int idx;
+
+	if (status == 0)
+		return IRQ_NONE;
+
+	/* Clear the bits we read on the overflow status register */
+	writel_relaxed(status, l3pmu->regs + L3_M_BC_OVSR);
+
+	for_each_set_bit(idx, &status, L3_NUM_COUNTERS) {
+		struct perf_event *event;
+		const struct l3cache_event_ops *ops;
+
+		event = l3pmu->events[idx];
+		if (!event)
+			continue;
+
+		/*
+		 * Since the IRQ is not enabled for events using long counters
+		 * we should never see one of those here, however, be consistent
+		 * and use the ops indirections like in the other operations.
+		 */
+
+		ops = l3cache_event_get_ops(event);
+		ops->update(event);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Implementation of abstract pmu functionality required by
+ * the core perf events code.
+ */
+
+static void qcom_l3_cache__pmu_enable(struct pmu *pmu)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(pmu);
+
+	/* Ensure the other programming commands are observed before enabling */
+	wmb();
+
+	writel_relaxed(BC_ENABLE, l3pmu->regs + L3_M_BC_CR);
+}
+
+static void qcom_l3_cache__pmu_disable(struct pmu *pmu)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(pmu);
+
+	writel_relaxed(0, l3pmu->regs + L3_M_BC_CR);
+
+	/* Ensure the basic counter unit is stopped before proceeding */
+	wmb();
+}
+
+/*
+ * We must NOT create groups containing events from multiple hardware PMUs,
+ * although mixing different software and hardware PMUs is allowed.
+ */
+static bool qcom_l3_cache__validate_event_group(struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader;
+	struct perf_event *sibling;
+	int counters = 0;
+
+	if (leader->pmu != event->pmu && !is_software_event(leader))
+		return false;
+
+	counters = event_num_counters(event);
+	counters += event_num_counters(leader);
+
+	list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
+		if (is_software_event(sibling))
+			continue;
+		if (sibling->pmu != event->pmu)
+			return false;
+		counters += event_num_counters(sibling);
+	}
+
+	/*
+	 * If the group requires more counters than the HW has, it
+	 * cannot ever be scheduled.
+	 */
+	return counters <= L3_NUM_COUNTERS;
+}
+
+static int qcom_l3_cache__event_init(struct perf_event *event)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+
+	/*
+	 * Is the event for this PMU?
+	 */
+	if (event->attr.type != event->pmu->type)
+		return -ENOENT;
+
+	/*
+	 * There are no per-counter mode filters in the PMU.
+	 */
+	if (event->attr.exclude_user || event->attr.exclude_kernel ||
+	    event->attr.exclude_hv || event->attr.exclude_idle)
+		return -EINVAL;
+
+	/*
+	 * Sampling not supported since these events are not core-attributable.
+	 */
+	if (hwc->sample_period)
+		return -EINVAL;
+
+	/*
+	 * Task mode not available, we run the counters as socket counters,
+	 * not attributable to any CPU and therefore cannot attribute per-task.
+	 */
+	if (event->cpu < 0)
+		return -EINVAL;
+
+	/* Validate the group */
+	if (!qcom_l3_cache__validate_event_group(event))
+		return -EINVAL;
+
+	hwc->idx = -1;
+
+	/*
+	 * Many perf core operations (eg. events rotation) operate on a
+	 * single CPU context. This is obvious for CPU PMUs, where one
+	 * expects the same sets of events being observed on all CPUs,
+	 * but can lead to issues for off-core PMUs, like this one, where
+	 * each event could be theoretically assigned to a different CPU.
+	 * To mitigate this, we enforce CPU assignment to one designated
+	 * processor (the one described in the "cpumask" attribute exported
+	 * by the PMU device). perf user space tools honor this and avoid
+	 * opening more than one copy of the events.
+	 */
+	event->cpu = cpumask_first(&l3pmu->cpumask);
+
+	return 0;
+}
+
+static void qcom_l3_cache__event_start(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	const struct l3cache_event_ops *ops = l3cache_event_get_ops(event);
+
+	hwc->state = 0;
+	ops->start(event);
+}
+
+static void qcom_l3_cache__event_stop(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	const struct l3cache_event_ops *ops = l3cache_event_get_ops(event);
+
+	if (hwc->state & PERF_HES_STOPPED)
+		return;
+
+	ops->stop(event, flags);
+	if (flags & PERF_EF_UPDATE)
+		ops->update(event);
+	hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+}
+
+static int qcom_l3_cache__event_add(struct perf_event *event, int flags)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	int order = event_uses_long_counter(event) ? 1 : 0;
+	int idx;
+
+	/*
+	 * Try to allocate a counter.
+	 */
+	idx = bitmap_find_free_region(l3pmu->used_mask, L3_NUM_COUNTERS, order);
+	if (idx < 0)
+		/* The counters are all in use. */
+		return -EAGAIN;
+
+	hwc->idx = idx;
+	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+	l3pmu->events[idx] = event;
+
+	if (flags & PERF_EF_START)
+		qcom_l3_cache__event_start(event, 0);
+
+	/* Propagate changes to the userspace mapping. */
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void qcom_l3_cache__event_del(struct perf_event *event, int flags)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	int order = event_uses_long_counter(event) ? 1 : 0;
+
+	/* Stop and clean up */
+	qcom_l3_cache__event_stop(event,  flags | PERF_EF_UPDATE);
+	l3pmu->events[hwc->idx] = NULL;
+	bitmap_release_region(l3pmu->used_mask, hwc->idx, order);
+
+	/* Propagate changes to the userspace mapping. */
+	perf_event_update_userpage(event);
+}
+
+static void qcom_l3_cache__event_read(struct perf_event *event)
+{
+	const struct l3cache_event_ops *ops = l3cache_event_get_ops(event);
+
+	ops->update(event);
+}
+
+/*
+ * Add sysfs attributes
+ *
+ * We export:
+ * - formats, used by perf user space and other tools to configure events
+ * - events, used by perf user space and other tools to create events
+ *   symbolically, e.g.:
+ *     perf stat -a -e l3cache_0_0/event=read-miss/ ls
+ *     perf stat -a -e l3cache_0_0/event=0x21/ ls
+ * - cpumask, used by perf user space and other tools to know on which CPUs
+ *   to open the events
+ */
+
+/* formats */
+
+static ssize_t l3cache_pmu_format_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct dev_ext_attribute *eattr;
+
+	eattr = container_of(attr, struct dev_ext_attribute, attr);
+	return sprintf(buf, "%s\n", (char *) eattr->var);
+}
+
+#define L3CACHE_PMU_FORMAT_ATTR(_name, _config)				      \
+	(&((struct dev_ext_attribute[]) {				      \
+		{ .attr = __ATTR(_name, 0444, l3cache_pmu_format_show, NULL), \
+		  .var = (void *) _config, }				      \
+	})[0].attr.attr)
+
+static struct attribute *qcom_l3_cache_pmu_formats[] = {
+	L3CACHE_PMU_FORMAT_ATTR(event, "config:0-7"),
+	L3CACHE_PMU_FORMAT_ATTR(lc, "config:" __stringify(L3_EVENT_LC_BIT)),
+	NULL,
+};
+
+static struct attribute_group qcom_l3_cache_pmu_format_group = {
+	.name = "format",
+	.attrs = qcom_l3_cache_pmu_formats,
+};
+
+/* events */
+
+static ssize_t l3cache_pmu_event_show(struct device *dev,
+				     struct device_attribute *attr, char *page)
+{
+	struct perf_pmu_events_attr *pmu_attr;
+
+	pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
+	return sprintf(page, "event=0x%02llx\n", pmu_attr->id);
+}
+
+#define L3CACHE_EVENT_ATTR(_name, _id)					     \
+	(&((struct perf_pmu_events_attr[]) {				     \
+		{ .attr = __ATTR(_name, 0444, l3cache_pmu_event_show, NULL), \
+		  .id = _id, }						     \
+	})[0].attr.attr)
+
+static struct attribute *qcom_l3_cache_pmu_events[] = {
+	L3CACHE_EVENT_ATTR(cycles, L3_EVENT_CYCLES),
+	L3CACHE_EVENT_ATTR(read-hit, L3_EVENT_READ_HIT),
+	L3CACHE_EVENT_ATTR(read-miss, L3_EVENT_READ_MISS),
+	L3CACHE_EVENT_ATTR(read-hit-d-side, L3_EVENT_READ_HIT_D),
+	L3CACHE_EVENT_ATTR(read-miss-d-side, L3_EVENT_READ_MISS_D),
+	L3CACHE_EVENT_ATTR(write-hit, L3_EVENT_WRITE_HIT),
+	L3CACHE_EVENT_ATTR(write-miss, L3_EVENT_WRITE_MISS),
+	NULL
+};
+
+static struct attribute_group qcom_l3_cache_pmu_events_group = {
+	.name = "events",
+	.attrs = qcom_l3_cache_pmu_events,
+};
+
+/* cpumask */
+
+static ssize_t qcom_l3_cache_pmu_cpumask_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct l3cache_pmu *l3pmu = to_l3cache_pmu(dev_get_drvdata(dev));
+
+	return cpumap_print_to_pagebuf(true, buf, &l3pmu->cpumask);
+}
+
+static DEVICE_ATTR(cpumask, 0444, qcom_l3_cache_pmu_cpumask_show, NULL);
+
+static struct attribute *qcom_l3_cache_pmu_cpumask_attrs[] = {
+	&dev_attr_cpumask.attr,
+	NULL,
+};
+
+static struct attribute_group qcom_l3_cache_pmu_cpumask_attr_group = {
+	.attrs = qcom_l3_cache_pmu_cpumask_attrs,
+};
+
+/*
+ * Per PMU device attribute groups
+ */
+static const struct attribute_group *qcom_l3_cache_pmu_attr_grps[] = {
+	&qcom_l3_cache_pmu_format_group,
+	&qcom_l3_cache_pmu_events_group,
+	&qcom_l3_cache_pmu_cpumask_attr_group,
+	NULL,
+};
+
+/*
+ * Probing functions and data.
+ */
+
+static int qcom_l3_cache_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct l3cache_pmu *l3pmu = hlist_entry_safe(node, struct l3cache_pmu, node);
+
+	/* If there is not a CPU/PMU association pick this CPU */
+	if (cpumask_empty(&l3pmu->cpumask))
+		cpumask_set_cpu(cpu, &l3pmu->cpumask);
+
+	return 0;
+}
+
+static int qcom_l3_cache_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
+{
+	struct l3cache_pmu *l3pmu = hlist_entry_safe(node, struct l3cache_pmu, node);
+	unsigned int target;
+
+	if (!cpumask_test_and_clear_cpu(cpu, &l3pmu->cpumask))
+		return 0;
+	target = cpumask_any_but(cpu_online_mask, cpu);
+	if (target >= nr_cpu_ids)
+		return 0;
+	perf_pmu_migrate_context(&l3pmu->pmu, cpu, target);
+	cpumask_set_cpu(target, &l3pmu->cpumask);
+	return 0;
+}
+
+static int qcom_l3_cache_pmu_probe(struct platform_device *pdev)
+{
+	struct l3cache_pmu *l3pmu;
+	struct acpi_device *acpi_dev;
+	struct resource *memrc;
+	int ret;
+	char *name;
+
+	/* Initialize the PMU data structures */
+
+	acpi_dev = ACPI_COMPANION(&pdev->dev);
+	if (!acpi_dev)
+		return -ENODEV;
+
+	l3pmu = devm_kzalloc(&pdev->dev, sizeof(*l3pmu), GFP_KERNEL);
+	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "l3cache_%s_%s",
+		      acpi_dev->parent->pnp.unique_id, acpi_dev->pnp.unique_id);
+	if (!l3pmu || !name)
+		return -ENOMEM;
+
+	l3pmu->pmu = (struct pmu) {
+		.task_ctx_nr	= perf_invalid_context,
+
+		.pmu_enable	= qcom_l3_cache__pmu_enable,
+		.pmu_disable	= qcom_l3_cache__pmu_disable,
+		.event_init	= qcom_l3_cache__event_init,
+		.add		= qcom_l3_cache__event_add,
+		.del		= qcom_l3_cache__event_del,
+		.start		= qcom_l3_cache__event_start,
+		.stop		= qcom_l3_cache__event_stop,
+		.read		= qcom_l3_cache__event_read,
+
+		.attr_groups	= qcom_l3_cache_pmu_attr_grps,
+	};
+
+	memrc = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	l3pmu->regs = devm_ioremap_resource(&pdev->dev, memrc);
+	if (IS_ERR(l3pmu->regs)) {
+		dev_err(&pdev->dev, "Can't map PMU @%pa\n", &memrc->start);
+		return PTR_ERR(l3pmu->regs);
+	}
+
+	qcom_l3_cache__init(l3pmu);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret <= 0)
+		return ret;
+
+	ret = devm_request_irq(&pdev->dev, ret, qcom_l3_cache__handle_irq, 0,
+			       name, l3pmu);
+	if (ret) {
+		dev_err(&pdev->dev, "Request for IRQ failed for slice @%pa\n",
+			&memrc->start);
+		return ret;
+	}
+
+	/* Add this instance to the list used by the offline callback */
+	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE, &l3pmu->node);
+	if (ret) {
+		dev_err(&pdev->dev, "Error %d registering hotplug", ret);
+		return ret;
+	}
+
+	ret = perf_pmu_register(&l3pmu->pmu, name, -1);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register L3 cache PMU (%d)\n", ret);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "Registered %s, type: %d\n", name, l3pmu->pmu.type);
+
+	return 0;
+}
+
+static const struct acpi_device_id qcom_l3_cache_pmu_acpi_match[] = {
+	{ "QCOM8081", },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, qcom_l3_cache_pmu_acpi_match);
+
+static struct platform_driver qcom_l3_cache_pmu_driver = {
+	.driver = {
+		.name = "qcom-l3cache-pmu",
+		.acpi_match_table = ACPI_PTR(qcom_l3_cache_pmu_acpi_match),
+	},
+	.probe = qcom_l3_cache_pmu_probe,
+};
+
+static int __init register_qcom_l3_cache_pmu_driver(void)
+{
+	int ret;
+
+	/* Install a hook to update the reader CPU in case it goes offline */
+	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
+				      "perf/qcom/l3cache:online",
+				      qcom_l3_cache_pmu_online_cpu,
+				      qcom_l3_cache_pmu_offline_cpu);
+	if (ret)
+		return ret;
+
+	return platform_driver_register(&qcom_l3_cache_pmu_driver);
+}
+device_initcall(register_qcom_l3_cache_pmu_driver);

include/linux/cpuhotplug.h

···
 	CPUHP_AP_ARM_VFP_STARTING,
 	CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING,
 	CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,
+	CPUHP_AP_PERF_ARM_ACPI_STARTING,
 	CPUHP_AP_PERF_ARM_STARTING,
 	CPUHP_AP_ARM_L2X0_STARTING,
 	CPUHP_AP_ARM_ARCH_TIMER_STARTING,
···
 	CPUHP_AP_PERF_ARM_CCN_ONLINE,
 	CPUHP_AP_PERF_ARM_L2X0_ONLINE,
 	CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
+	CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
 	CPUHP_AP_WORKQUEUE_ONLINE,
 	CPUHP_AP_RCUTREE_ONLINE,
 	CPUHP_AP_ONLINE_DYN,

include/linux/perf/arm_pmu.h

···
 	 * already have to allocate this struct per cpu.
 	 */
 	struct arm_pmu		*percpu_pmu;
+
+	int irq;
 };
 
 enum armpmu_attr_groups {
···
 	struct pmu	pmu;
 	cpumask_t	active_irqs;
 	cpumask_t	supported_cpus;
-	int		*irq_affinity;
 	char		*name;
 	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
 	void		(*enable)(struct perf_event *event);
···
 	void		(*start)(struct arm_pmu *);
 	void		(*stop)(struct arm_pmu *);
 	void		(*reset)(void *);
-	int		(*request_irq)(struct arm_pmu *, irq_handler_t handler);
-	void		(*free_irq)(struct arm_pmu *);
 	int		(*map_event)(struct perf_event *event);
 	int		num_events;
-	atomic_t	active_events;
-	struct mutex	reserve_mutex;
 	u64		max_period;
 	bool		secure_access; /* 32-bit ARM only */
 #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
···
 	struct notifier_block	cpu_pm_nb;
 	/* the attr_groups array must be NULL-terminated */
 	const struct attribute_group *attr_groups[ARMPMU_NR_ATTR_GROUPS + 1];
+
+	/* Only to be used by ACPI probing code */
+	unsigned long acpi_cpuid;
 };
 
 #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))
···
 						[PERF_COUNT_HW_CACHE_RESULT_MAX],
 		     u32 raw_event_mask);
 
+typedef int (*armpmu_init_fn)(struct arm_pmu *);
+
 struct pmu_probe_info {
 	unsigned int cpuid;
 	unsigned int mask;
-	int (*init)(struct arm_pmu *);
+	armpmu_init_fn init;
 };
 
 #define PMU_PROBE(_cpuid, _mask, _fn)	\
···
 int arm_pmu_device_probe(struct platform_device *pdev,
 			 const struct of_device_id *of_table,
 			 const struct pmu_probe_info *probe_table);
+
+#ifdef CONFIG_ACPI
+int arm_pmu_acpi_probe(armpmu_init_fn init_fn);
+#else
+static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; }
+#endif
+
+/* Internal functions only for core arm_pmu code */
+struct arm_pmu *armpmu_alloc(void);
+void armpmu_free(struct arm_pmu *pmu);
+int armpmu_register(struct arm_pmu *pmu);
+int armpmu_request_irqs(struct arm_pmu *armpmu);
+void armpmu_free_irqs(struct arm_pmu *armpmu);
+int armpmu_request_irq(struct arm_pmu *armpmu, int cpu);
+void armpmu_free_irq(struct arm_pmu *armpmu, int cpu);
 
 #define ARMV8_PMU_PDEV_NAME "armv8-pmu"