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SubjectRe: [PATCH v6 6/6] perf: ARM DynamIQ Shared Unit PMU support
On Mon, 21 Aug 2017 18:55:09 +0100
Suzuki K Poulose <suzuki.poulose@arm.com> wrote:

> Add support for the Cluster PMU part of the ARM DynamIQ Shared Unit (DSU).
> The DSU integrates one or more cores with an L3 memory system, control
> logic, and external interfaces to form a multicore cluster. The PMU
> allows counting the various events related to L3, SCU etc, along with
> providing a cycle counter.
>
> The PMU can be accessed via system registers, which are common
> to the cores in the same cluster. The PMU registers follow the
> semantics of the ARMv8 PMU, mostly, with the exception that
> the counters record the cluster wide events.
>
> This driver is mostly based on the ARMv8 and CCI PMU drivers.
> The driver only supports ARM64 at the moment. It can be extended
> to support ARM32 by providing register accessors like we do in
> arch/arm64/include/arm_dsu_pmu.h.
>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>

Hi Suzuki,

Was just reading this again out of curiosity and picked up on a couple of
really trivial things. Nothing that should slow down a merge, but if you happen
to be doing a v6...

Driver looks good to me.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Jonathan

> ---
> Changes since V5:
> - Address comments on V5 by Mark.
> - Use IRQ_NOBALANCING for IRQ handler
> - Don't expose events which could be unimplemented.
> - Get rid of dsu_pmu_event_supported and allow raw event
> code to be used without validating whether it is supported.
> - Rename "supported_cpus" mask to "associated_cpus"
> - Add Documentation for the PMU driver
> - Don't disable IRQ for dsu_pmu_{enable/disable}_counters
> - Use consistent return codes for validate_event/group calls.
> - Check PERF_ATTACH_TASK flag in event_init.
> - Allow missing CPUs in dsu_pmu_dt_get_cpus, to handle cases
> where kernel could have capped nr_cpus.
> - Cleanup sanity checking for the CPU before accessing DSU
> - Reject events with counting CPU not associated with the DSU.
> Changes since V4:
> - Reflect the changed generic helper for mapping CPU id
> Changes since V2:
> - Cleanup dsu_pmu_device_probe error handling.
> - Fix event validate_group to invert the result check of validate_event
> - Return errors if we failed to parse CPUs in the DSU.
> - Add MODULE_DEVICE_TABLE entry
> - Use hlist_entry_safe for converting cpuhp_node to dsu_pmu.
> ---
> Documentation/perf/arm_dsu_pmu.txt | 28 ++
> arch/arm64/include/asm/arm_dsu_pmu.h | 124 ++++++
> drivers/perf/Kconfig | 9 +
> drivers/perf/Makefile | 1 +
> drivers/perf/arm_dsu_pmu.c | 828 +++++++++++++++++++++++++++++++++++
> 5 files changed, 990 insertions(+)
> create mode 100644 Documentation/perf/arm_dsu_pmu.txt
> create mode 100644 arch/arm64/include/asm/arm_dsu_pmu.h
> create mode 100644 drivers/perf/arm_dsu_pmu.c
>
> diff --git a/Documentation/perf/arm_dsu_pmu.txt b/Documentation/perf/arm_dsu_pmu.txt
> new file mode 100644
> index 0000000..d611e15
> --- /dev/null
> +++ b/Documentation/perf/arm_dsu_pmu.txt
> @@ -0,0 +1,28 @@
> +ARM DynamIQ Shared Unit (DSU) PMU
> +==================================
> +
> +ARM DynamIQ Shared Unit integrates one or more cores with an L3 memory system,
> +control logic and external interfaces to form a multicore cluster. The PMU
> +allows counting the various events related to the L3 cache, Snoop Control Unit
> +etc, using 32bit independent counters. It also provides a 64bit cycle counter.
> +
> +The PMU can only be accessed via CPU system registers and are common to the
> +cores connected to the same DSU. Like most of the other uncore PMUs, DSU
> +PMU doesn't support process specific events and cannot be used in sampling mode.
> +
> +The DSU provides a bitmap for a subset of implemented events via hardware
> +registers. There is no way for the driver to determine if the other events
> +are available or not. Hence the driver exposes only those events advertised
> +by the DSU, in "events" directory under :
> +
> + /sys/bus/event_sources/devices/arm_dsu_<N>/
> +
> +The user should refer to the TRM of the product to figure out the supported events
> +and use the raw event code for the unlisted events.
> +
> +The driver also exposes the CPUs connected to the DSU instance in "associated_cpus".
> +
> +
> +e.g usage :
> +
> + perf stat -a -e arm_dsu_0/cycles/
> diff --git a/arch/arm64/include/asm/arm_dsu_pmu.h b/arch/arm64/include/asm/arm_dsu_pmu.h
> new file mode 100644
> index 0000000..5d1b0d9
> --- /dev/null
> +++ b/arch/arm64/include/asm/arm_dsu_pmu.h
> @@ -0,0 +1,124 @@
> +/*
> + * ARM DynamIQ Shared Unit (DSU) PMU Low level register access routines.
> + *
> + * Copyright (C) ARM Limited, 2017.
> + *
> + * Author: Suzuki K Poulose <suzuki.poulose@arm.com>
> + *
> + * 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 <asm/sysreg.h>
> +
> +
> +#define CLUSTERPMCR_EL1 sys_reg(3, 0, 15, 5, 0)
> +#define CLUSTERPMCNTENSET_EL1 sys_reg(3, 0, 15, 5, 1)
> +#define CLUSTERPMCNTENCLR_EL1 sys_reg(3, 0, 15, 5, 2)
> +#define CLUSTERPMOVSSET_EL1 sys_reg(3, 0, 15, 5, 3)
> +#define CLUSTERPMOVSCLR_EL1 sys_reg(3, 0, 15, 5, 4)
> +#define CLUSTERPMSELR_EL1 sys_reg(3, 0, 15, 5, 5)
> +#define CLUSTERPMINTENSET_EL1 sys_reg(3, 0, 15, 5, 6)
> +#define CLUSTERPMINTENCLR_EL1 sys_reg(3, 0, 15, 5, 7)
> +#define CLUSTERPMCCNTR_EL1 sys_reg(3, 0, 15, 6, 0)
> +#define CLUSTERPMXEVTYPER_EL1 sys_reg(3, 0, 15, 6, 1)
> +#define CLUSTERPMXEVCNTR_EL1 sys_reg(3, 0, 15, 6, 2)
> +#define CLUSTERPMMDCR_EL1 sys_reg(3, 0, 15, 6, 3)
> +#define CLUSTERPMCEID0_EL1 sys_reg(3, 0, 15, 6, 4)
> +#define CLUSTERPMCEID1_EL1 sys_reg(3, 0, 15, 6, 5)
> +
> +static inline u32 __dsu_pmu_read_pmcr(void)
> +{
> + return read_sysreg_s(CLUSTERPMCR_EL1);
> +}
> +
> +static inline void __dsu_pmu_write_pmcr(u32 val)
> +{
> + write_sysreg_s(val, CLUSTERPMCR_EL1);
> + isb();
> +}
> +
> +static inline u32 __dsu_pmu_getreset_overflow(void)
> +{
> + u32 val = read_sysreg_s(CLUSTERPMOVSCLR_EL1);
> + /* Clear the bit */
> + write_sysreg_s(val, CLUSTERPMOVSCLR_EL1);
> + isb();
> + return val;
> +}
> +
> +static inline void __dsu_pmu_select_counter(int counter)
> +{
> + write_sysreg_s(counter, CLUSTERPMSELR_EL1);
> + isb();
> +}
> +
> +static inline u64 __dsu_pmu_read_counter(int counter)
> +{
> + __dsu_pmu_select_counter(counter);
> + return read_sysreg_s(CLUSTERPMXEVCNTR_EL1);
> +}
> +
> +static inline void __dsu_pmu_write_counter(int counter, u64 val)
> +{
> + __dsu_pmu_select_counter(counter);
> + write_sysreg_s(val, CLUSTERPMXEVCNTR_EL1);
> + isb();
> +}
> +
> +static inline void __dsu_pmu_set_event(int counter, u32 event)
> +{
> + __dsu_pmu_select_counter(counter);
> + write_sysreg_s(event, CLUSTERPMXEVTYPER_EL1);
> + isb();
> +}
> +
> +static inline u64 __dsu_pmu_read_pmccntr(void)
> +{
> + return read_sysreg_s(CLUSTERPMCCNTR_EL1);
> +}
> +
> +static inline void __dsu_pmu_write_pmccntr(u64 val)
> +{
> + write_sysreg_s(val, CLUSTERPMCCNTR_EL1);
> + isb();
> +}
> +
> +static inline void __dsu_pmu_disable_counter(int counter)
> +{
> + write_sysreg_s(BIT(counter), CLUSTERPMCNTENCLR_EL1);
> + isb();
> +}
> +
> +static inline void __dsu_pmu_enable_counter(int counter)
> +{
> + write_sysreg_s(BIT(counter), CLUSTERPMCNTENSET_EL1);
> + isb();
> +}
> +
> +static inline void __dsu_pmu_counter_interrupt_enable(int counter)
> +{
> + write_sysreg_s(BIT(counter), CLUSTERPMINTENSET_EL1);
> + isb();
> +}
> +
> +static inline void __dsu_pmu_counter_interrupt_disable(int counter)
> +{
> + write_sysreg_s(BIT(counter), CLUSTERPMINTENCLR_EL1);
> + isb();
> +}
> +
> +
> +static inline u32 __dsu_pmu_read_pmceid(int n)
> +{
> + switch (n) {
> + case 0:
> + return read_sysreg_s(CLUSTERPMCEID0_EL1);
> + case 1:
> + return read_sysreg_s(CLUSTERPMCEID1_EL1);
> + default:
> + BUILD_BUG();
> + return 0;
> + }
> +}
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index e5197ff..ee3d7d1 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -17,6 +17,15 @@ config ARM_PMU_ACPI
> depends on ARM_PMU && ACPI
> def_bool y
>
> +config ARM_DSU_PMU
> + tristate "ARM DynamIQ Shared Unit (DSU) PMU"
> + depends on ARM64 && PERF_EVENTS
> + help
> + Provides support for performance monitor unit in ARM DynamIQ Shared
> + Unit (DSU). The DSU integrates one or more cores with an L3 memory
> + system, control logic. The PMU allows counting various events related
> + to DSU.
> +
> config QCOM_L2_PMU
> bool "Qualcomm Technologies L2-cache PMU"
> depends on ARCH_QCOM && ARM64 && ACPI
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index 6420bd4..0adb4f6 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -1,5 +1,6 @@
> obj-$(CONFIG_ARM_PMU) += arm_pmu.o arm_pmu_platform.o
> obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
> +obj-$(CONFIG_ARM_DSU_PMU) += arm_dsu_pmu.o
> obj-$(CONFIG_QCOM_L2_PMU) += qcom_l2_pmu.o
> obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c
> new file mode 100644
> index 0000000..623beeb
> --- /dev/null
> +++ b/drivers/perf/arm_dsu_pmu.c
> @@ -0,0 +1,828 @@
> +/*
> + * ARM DynamIQ Shared Unit (DSU) PMU driver
> + *
> + * Copyright (C) ARM Limited, 2017.
> + *
> + * Based on ARM CCI-PMU, ARMv8 PMU-v3 drivers.
> + *
> + * 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.
> + */
> +
> +#define PMUNAME "arm_dsu"
> +#define DRVNAME PMUNAME "_pmu"
> +#define pr_fmt(fmt) DRVNAME ": " fmt
> +
> +#include <linux/device.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/perf_event.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +
> +#include <asm/arm_dsu_pmu.h>
> +
> +/* PMU event codes */
> +#define DSU_PMU_EVT_CYCLES 0x11
> +#define DSU_PMU_EVT_CHAIN 0x1e
> +
> +#define DSU_PMU_MAX_COMMON_EVENTS 0x40
> +
> +#define DSU_PMU_MAX_HW_CNTRS 32
> +#define DSU_PMU_HW_COUNTER_MASK (DSU_PMU_MAX_HW_CNTRS - 1)
> +
> +#define CLUSTERPMCR_E BIT(0)
> +#define CLUSTERPMCR_P BIT(1)
> +#define CLUSTERPMCR_C BIT(2)
> +#define CLUSTERPMCR_N_SHIFT 11
> +#define CLUSTERPMCR_N_MASK 0x1f
> +#define CLUSTERPMCR_IDCODE_SHIFT 16
> +#define CLUSTERPMCR_IDCODE_MASK 0xff
> +#define CLUSTERPMCR_IMP_SHIFT 24
> +#define CLUSTERPMCR_IMP_MASK 0xff
> +#define CLUSTERPMCR_RES_MASK 0x7e8
> +#define CLUSTERPMCR_RES_VAL 0x40
> +
> +#define DSU_ACTIVE_CPU_MASK 0x0
> +#define DSU_ASSOCIATED_CPU_MASK 0x1
> +
> +/*
> + * We use the index of the counters as they appear in the counter
> + * bit maps in the PMU registers (e.g CLUSTERPMSELR).
> + * i.e,
> + * counter 0 - Bit 0
> + * counter 1 - Bit 1
> + * ...
> + * Cycle counter - Bit 31
> + */
> +#define DSU_PMU_IDX_CYCLE_COUNTER 31
> +
> +/* All event counters are 32bit, with a 64bit Cycle counter */
> +#define DSU_PMU_COUNTER_WIDTH(idx) \
> + (((idx) == DSU_PMU_IDX_CYCLE_COUNTER) ? 64 : 32)
> +
> +#define DSU_PMU_COUNTER_MASK(idx) \
> + GENMASK_ULL((DSU_PMU_COUNTER_WIDTH((idx)) - 1), 0)
> +
> +#define DSU_EXT_ATTR(_name, _func, _config) \
> + (&((struct dev_ext_attribute[]) { \
> + { \
> + .attr = __ATTR(_name, 0444, _func, NULL), \
> + .var = (void *)_config \
> + } \
> + })[0].attr.attr)
> +
> +#define DSU_EVENT_ATTR(_name, _config) \
> + DSU_EXT_ATTR(_name, dsu_pmu_sysfs_event_show, (unsigned long)_config)
> +
> +#define DSU_FORMAT_ATTR(_name, _config) \
> + DSU_EXT_ATTR(_name, dsu_pmu_sysfs_format_show, (char *)_config)
> +
> +#define DSU_CPUMASK_ATTR(_name, _config) \
> + DSU_EXT_ATTR(_name, dsu_pmu_cpumask_show, (unsigned long)_config)
> +
> +struct dsu_hw_events {
> + DECLARE_BITMAP(used_mask, DSU_PMU_MAX_HW_CNTRS);
> + struct perf_event *events[DSU_PMU_MAX_HW_CNTRS];
> +};
> +
> +/*
> + * struct dsu_pmu - DSU PMU descriptor
> + *
> + * @pmu_lock : Protects accesses to DSU PMU register from normal vs
> + * interrupt handler contexts

Trivial comment of the day - missing .

> + * @hw_events : Holds the event counter state.
> + * @associated_cpus : CPUs attached to the DSU.
> + * @active_cpu : CPU to which the PMU is bound for accesses.
> + * @cpuhp_node : Node for CPU hotplug notifier link.
> + * @num_counters : Number of event counters implemented by the PMU,
> + * excluding the cycle counter.
> + * @irq : Interrupt line for counter overflow.
> + * @cpmceid_bitmap : Bitmap for the availability of architected common
> + * events (event_code < 0x40).
> + */
> +struct dsu_pmu {
> + struct pmu pmu;
> + struct device *dev;
> + raw_spinlock_t pmu_lock;
> + struct dsu_hw_events hw_events;
> + cpumask_t associated_cpus;
> + cpumask_t active_cpu;
> + struct hlist_node cpuhp_node;
> + u8 num_counters;
> + int irq;
> + DECLARE_BITMAP(cpmceid_bitmap, DSU_PMU_MAX_COMMON_EVENTS);
> +};
> +
> +static unsigned long dsu_pmu_cpuhp_state;
> +
> +static inline struct dsu_pmu *to_dsu_pmu(struct pmu *pmu)
> +{
> + return container_of(pmu, struct dsu_pmu, pmu);
> +}
> +
> +static ssize_t dsu_pmu_sysfs_event_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct dev_ext_attribute *eattr = container_of(attr,
> + struct dev_ext_attribute, attr);
> + return snprintf(buf, PAGE_SIZE, "event=0x%lx\n",
> + (unsigned long)eattr->var);
> +}
> +
> +static ssize_t dsu_pmu_sysfs_format_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct dev_ext_attribute *eattr = container_of(attr,
> + struct dev_ext_attribute, attr);
> + return snprintf(buf, PAGE_SIZE, "%s\n", (char *)eattr->var);
> +}
> +
> +static ssize_t dsu_pmu_cpumask_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct pmu *pmu = dev_get_drvdata(dev);
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
> + struct dev_ext_attribute *eattr = container_of(attr,
> + struct dev_ext_attribute, attr);
> + unsigned long mask_id = (unsigned long)eattr->var;
> + const cpumask_t *cpumask;
> +
> + switch (mask_id) {
> + case DSU_ACTIVE_CPU_MASK:
> + cpumask = &dsu_pmu->active_cpu;
> + break;
> + case DSU_ASSOCIATED_CPU_MASK:
> + cpumask = &dsu_pmu->associated_cpus;
> + break;
> + default:
> + return 0;
> + }
> + return cpumap_print_to_pagebuf(true, buf, cpumask);
> +}
> +
> +static struct attribute *dsu_pmu_format_attrs[] = {
> + DSU_FORMAT_ATTR(event, "config:0-31"),
> + NULL,
> +};
> +
> +static const struct attribute_group dsu_pmu_format_attr_group = {
> + .name = "format",
> + .attrs = dsu_pmu_format_attrs,
> +};
> +
> +static struct attribute *dsu_pmu_event_attrs[] = {
> + DSU_EVENT_ATTR(cycles, 0x11),
> + DSU_EVENT_ATTR(bus_acecss, 0x19),
> + DSU_EVENT_ATTR(memory_error, 0x1a),
> + DSU_EVENT_ATTR(bus_cycles, 0x1d),
> + DSU_EVENT_ATTR(l3d_cache_allocate, 0x29),
> + DSU_EVENT_ATTR(l3d_cache_refill, 0x2a),
> + DSU_EVENT_ATTR(l3d_cache, 0x2b),
> + DSU_EVENT_ATTR(l3d_cache_wb, 0x2c),
> + NULL,
> +};
> +
> +static umode_t
> +dsu_pmu_event_attr_is_visible(struct kobject *kobj, struct attribute *attr,
> + int unused)
> +{
> + struct pmu *pmu = dev_get_drvdata(kobj_to_dev(kobj));
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
> + struct dev_ext_attribute *eattr = container_of(attr,
> + struct dev_ext_attribute, attr.attr);
> + unsigned long evt = (unsigned long)eattr->var;
> +
> + return test_bit(evt, dsu_pmu->cpmceid_bitmap) ? attr->mode : 0;
> +}
> +
> +static const struct attribute_group dsu_pmu_events_attr_group = {
> + .name = "events",
> + .attrs = dsu_pmu_event_attrs,
> + .is_visible = dsu_pmu_event_attr_is_visible,
> +};
> +
> +static struct attribute *dsu_pmu_cpumask_attrs[] = {
> + DSU_CPUMASK_ATTR(cpumask, DSU_ACTIVE_CPU_MASK),
> + DSU_CPUMASK_ATTR(associated_cpus, DSU_ASSOCIATED_CPU_MASK),
> + NULL,
> +};
> +
> +static const struct attribute_group dsu_pmu_cpumask_attr_group = {
> + .attrs = dsu_pmu_cpumask_attrs,
> +};
> +
> +static const struct attribute_group *dsu_pmu_attr_groups[] = {
> + &dsu_pmu_cpumask_attr_group,
> + &dsu_pmu_events_attr_group,
> + &dsu_pmu_format_attr_group,
> + NULL,
> +};
> +
> +static int dsu_pmu_get_online_cpu(struct dsu_pmu *dsu_pmu)
> +{
> + return cpumask_first_and(&dsu_pmu->associated_cpus, cpu_online_mask);
> +}
> +
> +static int dsu_pmu_get_online_cpu_any_but(struct dsu_pmu *dsu_pmu, int cpu)
> +{
> + struct cpumask online_supported;
> +
> + cpumask_and(&online_supported,
> + &dsu_pmu->associated_cpus, cpu_online_mask);
> + return cpumask_any_but(&online_supported, cpu);
> +}
> +
> +static inline bool dsu_pmu_counter_valid(struct dsu_pmu *dsu_pmu, u32 idx)
> +{
> + return (idx < dsu_pmu->num_counters) ||
> + (idx == DSU_PMU_IDX_CYCLE_COUNTER);
> +}
> +
> +static inline u64 dsu_pmu_read_counter(struct perf_event *event)
> +{
> + u64 val = 0;

I'm doing well on trivial comments today. Val is always set so
no need to assign a default value here.

> + unsigned long flags;
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> + int idx = event->hw.idx;
> +
> + if (WARN_ON(!cpumask_test_cpu(smp_processor_id(),
> + &dsu_pmu->active_cpu)))
> + return 0;
> +
> + if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
> + dev_err(event->pmu->dev,
> + "Trying reading invalid counter %d\n", idx);
> + return 0;
> + }
> +
> + raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
> + if (idx == DSU_PMU_IDX_CYCLE_COUNTER)
> + val = __dsu_pmu_read_pmccntr();
> + else
> + val = __dsu_pmu_read_counter(idx);
> + raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
> +
> + return val;
> +}
> +
> +static void dsu_pmu_write_counter(struct perf_event *event, u64 val)
> +{
> + unsigned long flags;
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> + int idx = event->hw.idx;
> +
> + if (WARN_ON(!cpumask_test_cpu(smp_processor_id(),
> + &dsu_pmu->active_cpu)))
> + return;
> +
> + if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
> + dev_err(event->pmu->dev,
> + "writing to invalid counter %d\n", idx);
> + return;
> + }
> +
> + val &= DSU_PMU_COUNTER_MASK(idx);

Seems a little odd to do this as opposed to error out if the value
is too large. Perhaps a comment to justify?

> + raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
> + if (idx == DSU_PMU_IDX_CYCLE_COUNTER)
> + __dsu_pmu_write_pmccntr(val);
> + else
> + __dsu_pmu_write_counter(idx, val);
> + raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
> +}
> +
> +static int dsu_pmu_get_event_idx(struct dsu_hw_events *hw_events,
> + struct perf_event *event)
> +{
> + int idx;
> + unsigned long evtype = event->attr.config;
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> + unsigned long *used_mask = hw_events->used_mask;
> +
> + if (evtype == DSU_PMU_EVT_CYCLES) {
> + if (test_and_set_bit(DSU_PMU_IDX_CYCLE_COUNTER, used_mask))
> + return -EAGAIN;
> + return DSU_PMU_IDX_CYCLE_COUNTER;
> + }
> +
> + idx = find_next_zero_bit(used_mask, dsu_pmu->num_counters, 0);
> + if (idx >= dsu_pmu->num_counters)
> + return -EAGAIN;
> + set_bit(idx, hw_events->used_mask);
> + return idx;
> +}
> +
> +static void dsu_pmu_enable_counter(struct dsu_pmu *dsu_pmu, int idx)
> +{
> + __dsu_pmu_counter_interrupt_enable(idx);
> + __dsu_pmu_enable_counter(idx);
> +}
> +
> +static void dsu_pmu_disable_counter(struct dsu_pmu *dsu_pmu, int idx)
> +{
> + __dsu_pmu_disable_counter(idx);
> + __dsu_pmu_counter_interrupt_disable(idx);
> +}
> +
> +static inline void dsu_pmu_set_event(struct dsu_pmu *dsu_pmu,
> + struct perf_event *event)
> +{
> + int idx = event->hw.idx;
> + unsigned long flags;
> +
> + if (!dsu_pmu_counter_valid(dsu_pmu, idx)) {
> + dev_err(event->pmu->dev,
> + "Trying to set invalid counter %d\n", idx);
> + return;
> + }
> +
> + raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
> + __dsu_pmu_set_event(idx, event->hw.config_base);
> + raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
> +}
> +
> +static void dsu_pmu_event_update(struct perf_event *event)
> +{
> + struct hw_perf_event *hwc = &event->hw;
> + u64 delta, prev_count, new_count;
> +
> + do {
> + /* We may also be called from the irq handler */
> + prev_count = local64_read(&hwc->prev_count);
> + new_count = dsu_pmu_read_counter(event);
> + } while (local64_cmpxchg(&hwc->prev_count, prev_count, new_count) !=
> + prev_count);
> + delta = (new_count - prev_count) & DSU_PMU_COUNTER_MASK(hwc->idx);
> + local64_add(delta, &event->count);
> +}
> +
> +static void dsu_pmu_read(struct perf_event *event)
> +{
> + dsu_pmu_event_update(event);
> +}
> +
> +static inline u32 dsu_pmu_getreset_overflow(void)
> +{
> + return __dsu_pmu_getreset_overflow();
> +}
> +
> +/**
> + * dsu_pmu_set_event_period: Set the period for the counter.
> + *
> + * All DSU PMU event counters, except the cycle counter are 32bit
> + * counters. To handle cases of extreme interrupt latency, we program
> + * the counter with half of the max count for the counters.
> + */
> +static void dsu_pmu_set_event_period(struct perf_event *event)
> +{
> + int idx = event->hw.idx;
> + u64 val = DSU_PMU_COUNTER_MASK(idx) >> 1;
> +
> + local64_set(&event->hw.prev_count, val);
> + dsu_pmu_write_counter(event, val);
> +}
> +
> +static irqreturn_t dsu_pmu_handle_irq(int irq_num, void *dev)
> +{
> + int i;
> + bool handled = false;
> + struct dsu_pmu *dsu_pmu = dev;
> + struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
> + unsigned long overflow, workset;
> +
> + overflow = dsu_pmu_getreset_overflow();
> + bitmap_and(&workset, &overflow, hw_events->used_mask,
> + DSU_PMU_MAX_HW_CNTRS);
> +
> + if (!workset)
> + return IRQ_NONE;
> +
> + for_each_set_bit(i, &workset, DSU_PMU_MAX_HW_CNTRS) {
> + struct perf_event *event = hw_events->events[i];
> +
> + if (!event)
> + continue;
> + dsu_pmu_event_update(event);
> + dsu_pmu_set_event_period(event);
> +
> + handled = true;
> + }
> +
> + return IRQ_RETVAL(handled);
> +}
> +
> +static void dsu_pmu_start(struct perf_event *event, int pmu_flags)
> +{
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> +
> + /* We always reprogram the counter */
> + if (pmu_flags & PERF_EF_RELOAD)
> + WARN_ON(!(event->hw.state & PERF_HES_UPTODATE));
> + dsu_pmu_set_event_period(event);
> + if (event->hw.idx != DSU_PMU_IDX_CYCLE_COUNTER)
> + dsu_pmu_set_event(dsu_pmu, event);
> + event->hw.state = 0;
> + dsu_pmu_enable_counter(dsu_pmu, event->hw.idx);
> +}
> +
> +static void dsu_pmu_stop(struct perf_event *event, int pmu_flags)
> +{
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> +
> + if (event->hw.state & PERF_HES_STOPPED)
> + return;
> + dsu_pmu_disable_counter(dsu_pmu, event->hw.idx);
> + dsu_pmu_event_update(event);
> + event->hw.state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +}
> +
> +static int dsu_pmu_add(struct perf_event *event, int flags)
> +{
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> + struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
> + struct hw_perf_event *hwc = &event->hw;
> + int idx;
> +
> + if (WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(),
> + &dsu_pmu->active_cpu)))
> + return -ENOENT;
> +
> + idx = dsu_pmu_get_event_idx(hw_events, event);
> + if (idx < 0)
> + return idx;
> +
> + hwc->idx = idx;
> + hw_events->events[idx] = event;
> + hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +
> + if (flags & PERF_EF_START)
> + dsu_pmu_start(event, PERF_EF_RELOAD);
> +
> + perf_event_update_userpage(event);
> + return 0;
> +}
> +
> +static void dsu_pmu_del(struct perf_event *event, int flags)
> +{
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> + struct dsu_hw_events *hw_events = &dsu_pmu->hw_events;
> + struct hw_perf_event *hwc = &event->hw;
> + int idx = hwc->idx;
> +
> + dsu_pmu_stop(event, PERF_EF_UPDATE);
> + hw_events->events[idx] = NULL;
> + clear_bit(idx, hw_events->used_mask);
> + perf_event_update_userpage(event);
> +}
> +
> +static void dsu_pmu_enable(struct pmu *pmu)
> +{
> + u32 pmcr;
> + unsigned long flags;
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
> + int enabled = bitmap_weight(dsu_pmu->hw_events.used_mask,
> + DSU_PMU_MAX_HW_CNTRS);

!bitmap_empty might be slightly cheaper as we don't actually care
about the weight.

> +
> + if (!enabled)
> + return;
> +
> + raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
> + pmcr = __dsu_pmu_read_pmcr();
> + pmcr |= CLUSTERPMCR_E;
> + __dsu_pmu_write_pmcr(pmcr);
> + raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
> +}
> +
> +static void dsu_pmu_disable(struct pmu *pmu)
> +{
> + u32 pmcr;
> + unsigned long flags;
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(pmu);
> +
> + raw_spin_lock_irqsave(&dsu_pmu->pmu_lock, flags);
> + pmcr = __dsu_pmu_read_pmcr();
> + pmcr &= ~CLUSTERPMCR_E;
> + __dsu_pmu_write_pmcr(pmcr);
> + raw_spin_unlock_irqrestore(&dsu_pmu->pmu_lock, flags);
> +}
> +
> +static bool dsu_pmu_validate_event(struct pmu *pmu,
> + struct dsu_hw_events *hw_events,
> + struct perf_event *event)
> +{
> + if (is_software_event(event))
> + return true;
> + /* Reject groups spanning multiple HW PMUs. */
> + if (event->pmu != pmu)
> + return false;
> + return dsu_pmu_get_event_idx(hw_events, event) >= 0;
> +}
> +
> +/*
> + * Make sure the group of events can be scheduled at once
> + * on the PMU.
> + */
> +static bool dsu_pmu_validate_group(struct perf_event *event)
> +{
> + struct perf_event *sibling, *leader = event->group_leader;
> + struct dsu_hw_events fake_hw;
> +
> + if (event->group_leader == event)
> + return true;
> +
> + memset(fake_hw.used_mask, 0, sizeof(fake_hw.used_mask));
> + if (!dsu_pmu_validate_event(event->pmu, &fake_hw, leader))
> + return false;
> + list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
> + if (!dsu_pmu_validate_event(event->pmu, &fake_hw, sibling))
> + return false;
> + }
> + return dsu_pmu_validate_event(event->pmu, &fake_hw, event);
> +}
> +
> +static int dsu_pmu_event_init(struct perf_event *event)
> +{
> + struct dsu_pmu *dsu_pmu = to_dsu_pmu(event->pmu);
> +
> + if (event->attr.type != event->pmu->type)
> + return -ENOENT;
> +
> + /* We don't support sampling */
> + if (is_sampling_event(event)) {
> + dev_dbg(dsu_pmu->pmu.dev, "Can't support sampling events\n");
> + return -EOPNOTSUPP;
> + }
> +
> + /* We cannot support task bound events */
> + if (event->cpu < 0 || event->attach_state & PERF_ATTACH_TASK) {
> + dev_dbg(dsu_pmu->pmu.dev, "Can't support per-task counters\n");
> + return -EINVAL;
> + }
> +
> + if (has_branch_stack(event) ||
> + event->attr.exclude_user ||
> + event->attr.exclude_kernel ||
> + event->attr.exclude_hv ||
> + event->attr.exclude_idle ||
> + event->attr.exclude_host ||
> + event->attr.exclude_guest) {
> + dev_dbg(dsu_pmu->pmu.dev, "Can't support filtering\n");
> + return -EINVAL;
> + }
> +
> + if (!dsu_pmu_validate_group(event))
> + return -EINVAL;
> + if (!cpumask_test_cpu(event->cpu, &dsu_pmu->associated_cpus)) {
> + dev_dbg(dsu_pmu->pmu.dev,
> + "Requested cpu is not associated with the DSU\n");
> + return -EINVAL;
> + }
> + /*
> + * Choose the current active CPU to read the events. We don't want
> + * to migrate the event contexts, irq handling etc to the requested
> + * CPU. As long as the requested CPU is within the same DSU, we
> + * are fine.
> + */
> + event->cpu = cpumask_first(&dsu_pmu->active_cpu);
> + if (event->cpu >= nr_cpu_ids)
> + return -EINVAL;
> +
> + event->hw.config_base = event->attr.config;
> + return 0;
> +}
> +
> +static struct dsu_pmu *dsu_pmu_alloc(struct platform_device *pdev)
> +{
> + struct dsu_pmu *dsu_pmu;
> +
> + dsu_pmu = devm_kzalloc(&pdev->dev, sizeof(*dsu_pmu), GFP_KERNEL);
> + if (!dsu_pmu)
> + return ERR_PTR(-ENOMEM);
> +
> + raw_spin_lock_init(&dsu_pmu->pmu_lock);
> + return dsu_pmu;
> +}
> +
> +/**
> + * dsu_pmu_dt_get_cpus: Get the list of CPUs in the cluster.
> + */
> +static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
> +{
> + int i = 0, n, cpu;
> + struct device_node *cpu_node;
> +
> + n = of_count_phandle_with_args(dev, "cpus", NULL);
> + if (n <= 0)
> + return -ENODEV;
> + for (; i < n; i++) {
> + cpu_node = of_parse_phandle(dev, "cpus", i);
> + if (!cpu_node)
> + break;
> + cpu = of_cpu_node_to_id(cpu_node);
> + of_node_put(cpu_node);
> + /*
> + * We have to ignore the failures here and continue scanning
> + * the list to handle cases where the nr_cpus could be capped
> + * in the running kernel.
> + */
> + if (cpu < 0)
> + continue;
> + cpumask_set_cpu(cpu, mask);
> + }
> + return 0;
> +}
> +
> +/*
> + * dsu_pmu_probe_pmu: Probe the PMU details on a CPU in the cluster.
> + */
> +static void dsu_pmu_probe_pmu(void *data)
> +{
> + struct dsu_pmu *dsu_pmu = data;
> + u64 num_counters;
> + u32 cpmceid[2];
> +
> + num_counters = (__dsu_pmu_read_pmcr() >> CLUSTERPMCR_N_SHIFT) &
> + CLUSTERPMCR_N_MASK;
> + /* We can only support upto 31 independent counters */
> + if (WARN_ON(num_counters > 31))
> + num_counters = 31;
> + dsu_pmu->num_counters = num_counters;
> + if (!dsu_pmu->num_counters)
> + return;
> + cpmceid[0] = __dsu_pmu_read_pmceid(0);
> + cpmceid[1] = __dsu_pmu_read_pmceid(1);
> + bitmap_from_u32array(dsu_pmu->cpmceid_bitmap,
> + DSU_PMU_MAX_COMMON_EVENTS,
> + cpmceid,
> + ARRAY_SIZE(cpmceid));
> +}
> +
> +static int dsu_pmu_device_probe(struct platform_device *pdev)
> +{
> + int irq, rc, cpu;
> + struct dsu_pmu *dsu_pmu;
> + char *name;
> + static atomic_t pmu_idx = ATOMIC_INIT(-1);
> +
> + dsu_pmu = dsu_pmu_alloc(pdev);
> + if (IS_ERR(dsu_pmu))
> + return PTR_ERR(dsu_pmu);
> +
> + rc = dsu_pmu_dt_get_cpus(pdev->dev.of_node, &dsu_pmu->associated_cpus);
> + if (rc) {
> + dev_warn(&pdev->dev, "Failed to parse the CPUs\n");
> + return rc;
> + }
> +
> + rc = smp_call_function_any(&dsu_pmu->associated_cpus,
> + dsu_pmu_probe_pmu,
> + dsu_pmu, 1);
> + if (rc)
> + return rc;
> + if (!dsu_pmu->num_counters)
> + return -ENODEV;
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0) {
> + dev_warn(&pdev->dev, "Failed to find IRQ\n");
> + return -EINVAL;
> + }
> +
> + name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s_%d",
> + PMUNAME, atomic_inc_return(&pmu_idx));
> + rc = devm_request_irq(&pdev->dev, irq, dsu_pmu_handle_irq,
> + IRQF_NOBALANCING, name, dsu_pmu);
> + if (rc) {
> + dev_warn(&pdev->dev, "Failed to request IRQ %d\n", irq);
> + return rc;
> + }
> +
> + /*
> + * Find one CPU in the DSU to handle the IRQs.
> + * It is highly unlikely that we would fail
> + * to find one, given the probing has succeeded.
> + */
> + cpu = dsu_pmu_get_online_cpu(dsu_pmu);
> + if (cpu >= nr_cpu_ids)
> + return -ENODEV;
> + cpumask_set_cpu(cpu, &dsu_pmu->active_cpu);
> + rc = irq_set_affinity_hint(irq, &dsu_pmu->active_cpu);
> + if (rc) {
> + dev_warn(&pdev->dev, "Failed to force IRQ affinity for %d\n",
> + irq);
> + return rc;
> + }
> +
> + platform_set_drvdata(pdev, dsu_pmu);
> + rc = cpuhp_state_add_instance(dsu_pmu_cpuhp_state,
> + &dsu_pmu->cpuhp_node);
> + if (rc)
> + goto irq_cleanup;
> +
> + dsu_pmu->irq = irq;
> + dsu_pmu->pmu = (struct pmu) {
> + .task_ctx_nr = perf_invalid_context,
> +
> + .pmu_enable = dsu_pmu_enable,
> + .pmu_disable = dsu_pmu_disable,
> + .event_init = dsu_pmu_event_init,
> + .add = dsu_pmu_add,
> + .del = dsu_pmu_del,
> + .start = dsu_pmu_start,
> + .stop = dsu_pmu_stop,
> + .read = dsu_pmu_read,
> +
> + .attr_groups = dsu_pmu_attr_groups,
> + };
> +
> + rc = perf_pmu_register(&dsu_pmu->pmu, name, -1);
> + if (rc)
> + goto cpuhp_cleanup;
> +
> + dev_info(&pdev->dev, "Registered %s with %d event counters",
> + name, dsu_pmu->num_counters);
> + return 0;
> +
> +cpuhp_cleanup:
> + cpuhp_state_remove_instance(dsu_pmu_cpuhp_state, &dsu_pmu->cpuhp_node);
> +irq_cleanup:
> + irq_set_affinity_hint(dsu_pmu->irq, NULL);
> + return rc;
> +}
> +
> +static int dsu_pmu_device_remove(struct platform_device *pdev)
> +{
> + struct dsu_pmu *dsu_pmu = platform_get_drvdata(pdev);
> +
> + perf_pmu_unregister(&dsu_pmu->pmu);
> + cpuhp_state_remove_instance(dsu_pmu_cpuhp_state, &dsu_pmu->cpuhp_node);
> + irq_set_affinity_hint(dsu_pmu->irq, NULL);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id dsu_pmu_of_match[] = {
> + { .compatible = "arm,dsu-pmu", },
> + {},
> +};
> +
> +static struct platform_driver dsu_pmu_driver = {
> + .driver = {
> + .name = DRVNAME,
> + .of_match_table = of_match_ptr(dsu_pmu_of_match),
> + },
> + .probe = dsu_pmu_device_probe,
> + .remove = dsu_pmu_device_remove,
> +};
> +
> +static int dsu_pmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
> +{
> + int dst;
> + struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu,
> + cpuhp_node);
> +
> + if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu))
> + return 0;
> +
> + dst = dsu_pmu_get_online_cpu_any_but(dsu_pmu, cpu);
> + if (dst < nr_cpu_ids) {
> + cpumask_set_cpu(dst, &dsu_pmu->active_cpu);
> + perf_pmu_migrate_context(&dsu_pmu->pmu, cpu, dst);
> + irq_set_affinity_hint(dsu_pmu->irq, &dsu_pmu->active_cpu);
> + }
> +
> + return 0;
> +}
> +
> +static int __init dsu_pmu_init(void)
> +{
> + int ret;
> +
> + ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> + DRVNAME,
> + NULL,
> + dsu_pmu_cpu_teardown);
> + if (ret < 0)
> + return ret;
> + dsu_pmu_cpuhp_state = ret;
> + return platform_driver_register(&dsu_pmu_driver);
> +}
> +
> +static void __exit dsu_pmu_exit(void)
> +{
> + platform_driver_unregister(&dsu_pmu_driver);
> + cpuhp_remove_multi_state(dsu_pmu_cpuhp_state);
> +}
> +
> +module_init(dsu_pmu_init);
> +module_exit(dsu_pmu_exit);
> +
> +MODULE_DEVICE_TABLE(of, dsu_pmu_of_match);
> +MODULE_DESCRIPTION("Perf driver for ARM DynamIQ Shared Unit");
> +MODULE_AUTHOR("Suzuki K Poulose <suzuki.poulose@arm.com>");
> +MODULE_LICENSE("GPL v2");

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