Message-ID: <b25b462e-d604-2597-820d-289e0a50f365@arm.com>
Date:   Thu, 15 Nov 2018 22:45:29 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     "Kulkarni, Ganapatrao" <Ganapatrao.Kulkarni@...ium.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Cc:     "Will.Deacon@....com" <Will.Deacon@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "Nair, Jayachandran" <Jayachandran.Nair@...ium.com>,
        "Richter, Robert" <Robert.Richter@...ium.com>,
        "Lomovtsev, Vadim" <Vadim.Lomovtsev@...ium.com>,
        Jan Glauber <Jan.Glauber@...ium.com>,
        "gklkml16@...il.com" <gklkml16@...il.com>
Subject: Re: [PATCH v7 2/2] ThunderX2, perf : Add Cavium ThunderX2 SoC UNCORE
 PMU driver

Hi,

On 10/25/2018 06:59 AM, Kulkarni, Ganapatrao wrote:
> This patch adds a perf driver for the PMU UNCORE devices DDR4 Memory
> Controller(DMC) and Level 3 Cache(L3C). Each PMU supports up to 4
> counters. All counters lack overflow interrupt and are
> sampled periodically.

The patch looks OK overall. Some minor comments below.

> 
> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
> ---
>   drivers/perf/Kconfig         |   9 +
>   drivers/perf/Makefile        |   1 +
>   drivers/perf/thunderx2_pmu.c | 867 +++++++++++++++++++++++++++++++++++
>   include/linux/cpuhotplug.h   |   1 +
>   4 files changed, 878 insertions(+)
>   create mode 100644 drivers/perf/thunderx2_pmu.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 08ebaf7cca8b..c1956b1af2bb 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -87,6 +87,15 @@ config QCOM_L3_PMU
>   	   Adds the L3 cache PMU into the perf events subsystem for
>   	   monitoring L3 cache events.
>   
> +config THUNDERX2_PMU
> +        tristate "Cavium ThunderX2 SoC PMU UNCORE"
> +	depends on ARCH_THUNDER2 && ARM64 && ACPI && NUMA
> +        default m
> +	help
> +	  Provides support for ThunderX2 UNCORE events.
> +	  The SoC has PMU support in its L3 cache controller (L3C) and
> +	  in the DDR4 Memory Controller (DMC).
> +
>   config XGENE_PMU
>           depends on ARCH_XGENE
>           bool "APM X-Gene SoC PMU"
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index b3902bd37d53..909f27fd9db3 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -7,5 +7,6 @@ obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
>   obj-$(CONFIG_HISI_PMU) += hisilicon/
>   obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
>   obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> +obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
>   obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
>   obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
> diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
> new file mode 100644
> index 000000000000..450d36c6a1e1
> --- /dev/null
> +++ b/drivers/perf/thunderx2_pmu.c
> @@ -0,0 +1,867 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * CAVIUM THUNDERX2 SoC PMU UNCORE
> + * Copyright (C) 2018 Cavium Inc.
> + * Author: Ganapatrao Kulkarni <gkulkarni@...ium.com>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/perf_event.h>
> +#include <linux/platform_device.h>
> +
> +/* Each ThunderX2(TX2) Socket has a L3C and DMC UNCORE PMU device.
> + * Each UNCORE PMU device consists of 4 independent programmable counters.
> + * Counters are 32 bit and do not support overflow interrupt,
> + * they need to be sampled before overflow(i.e, at every 2 seconds).
> + */
> +
> +#define TX2_PMU_MAX_COUNTERS		4
> +#define TX2_PMU_DMC_CHANNELS		8
> +#define TX2_PMU_L3_TILES		16
> +
> +#define TX2_PMU_HRTIMER_INTERVAL	(2 * NSEC_PER_SEC)
> +#define GET_EVENTID(ev)			((ev->hw.config) & 0x1ff)

> +#define GET_COUNTERID(ev)		((ev->hw.idx) & 0xf)

If the number of counters are 4, should the mask be 0x3 instead ?

> +#define DMC_EVENT_CFG(idx, val)		((val) << (((idx) * 8) + 1))

If I understand this correctly, you are accommodating bits[5:1] of the
8bit counter by "+1". It is worth adding a comment about the bit
position here.


> +
> +#define L3C_COUNTER_CTL			0xA8
> +#define L3C_COUNTER_DATA		0xAC
> +#define DMC_COUNTER_CTL			0x234
> +#define DMC_COUNTER_DATA		0x240
> +
> +/* L3C event IDs */
> +#define L3_EVENT_READ_REQ		0xD
> +#define L3_EVENT_WRITEBACK_REQ		0xE
> +#define L3_EVENT_INV_N_WRITE_REQ	0xF
> +#define L3_EVENT_INV_REQ		0x10
> +#define L3_EVENT_EVICT_REQ		0x13
> +#define L3_EVENT_INV_N_WRITE_HIT	0x14
> +#define L3_EVENT_INV_HIT		0x15
> +#define L3_EVENT_READ_HIT		0x17
> +#define L3_EVENT_MAX			0x18
> +
> +/* DMC event IDs */
> +#define DMC_EVENT_COUNT_CYCLES		0x1
> +#define DMC_EVENT_WRITE_TXNS		0xB
> +#define DMC_EVENT_DATA_TRANSFERS	0xD
> +#define DMC_EVENT_READ_TXNS		0xF
> +#define DMC_EVENT_MAX			0x10
> +
> +enum tx2_uncore_type {
> +	PMU_TYPE_L3C,
> +	PMU_TYPE_DMC,
> +	PMU_TYPE_INVALID,
> +};
> +
> +/*
> + * pmu on each socket has 2 uncore devices(dmc and l3c),
> + * each device has 4 counters.
> + */
> +struct tx2_uncore_pmu {
> +	struct hlist_node hpnode;
> +	struct list_head  entry;
> +	struct pmu pmu;
> +	char *name;
> +	int node;
> +	int cpu;
> +	u32    max_counters;
> +	u32    prorate_factor;
> +	u32    max_events;
> +	u64 hrtimer_interval;
> +	void __iomem *base;
> +	DECLARE_BITMAP(active_counters, TX2_PMU_MAX_COUNTERS);
> +	struct perf_event *events[TX2_PMU_MAX_COUNTERS];
> +	struct device *dev;
> +	struct hrtimer hrtimer;
> +	const struct attribute_group **attr_groups;
> +	enum tx2_uncore_type type;
> +	raw_spinlock_t lock;
> +	void	(*init_cntr_base)(struct perf_event *event,
> +			struct tx2_uncore_pmu *tx2_pmu);
> +	void	(*stop_event)(struct perf_event *event);
> +	void	(*start_event)(struct perf_event *event, int flags);
> +};
> +
> +static LIST_HEAD(tx2_pmus);
> +
> +static inline struct tx2_uncore_pmu *pmu_to_tx2_pmu(struct pmu *pmu)
> +{
> +	return container_of(pmu, struct tx2_uncore_pmu, pmu);
> +}
> +
> +/*
> + * sysfs format attributes
> + */
> +static ssize_t tx2_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 FORMAT_ATTR(_name, _config) \
> +	(&((struct dev_ext_attribute[]) { \
> +	   { \
> +	   .attr = __ATTR(_name, 0444, tx2_pmu_format_show, NULL), \
> +	   .var = (void *) _config, \
> +	   } \
> +	})[0].attr.attr)
> +
> +static struct attribute *l3c_pmu_format_attrs[] = {
> +	FORMAT_ATTR(event,	"config:0-4"),
> +	NULL,
> +};
> +
> +static struct attribute *dmc_pmu_format_attrs[] = {
> +	FORMAT_ATTR(event,	"config:0-4"),
> +	NULL,
> +};
> +
> +static const struct attribute_group l3c_pmu_format_attr_group = {
> +	.name = "format",
> +	.attrs = l3c_pmu_format_attrs,
> +};
> +
> +static const struct attribute_group dmc_pmu_format_attr_group = {
> +	.name = "format",
> +	.attrs = dmc_pmu_format_attrs,
> +};
> +
> +/*
> + * sysfs event attributes
> + */
> +static ssize_t tx2_pmu_event_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, "config=0x%lx\n", (unsigned long) eattr->var);
> +}
> +
> +#define EVENT_ATTR(_name, _config) \
> +	(&((struct dev_ext_attribute[]) { \
> +	   { \
> +	   .attr = __ATTR(_name, 0444, tx2_pmu_event_show, NULL), \
> +	   .var = (void *) _config, \
> +	   } \
> +	 })[0].attr.attr)
> +
> +static struct attribute *l3c_pmu_events_attrs[] = {
> +	EVENT_ATTR(read_request,		L3_EVENT_READ_REQ),
> +	EVENT_ATTR(writeback_request,		L3_EVENT_WRITEBACK_REQ),
> +	EVENT_ATTR(inv_nwrite_request,		L3_EVENT_INV_N_WRITE_REQ),
> +	EVENT_ATTR(inv_request,			L3_EVENT_INV_REQ),
> +	EVENT_ATTR(evict_request,		L3_EVENT_EVICT_REQ),
> +	EVENT_ATTR(inv_nwrite_hit,		L3_EVENT_INV_N_WRITE_HIT),
> +	EVENT_ATTR(inv_hit,			L3_EVENT_INV_HIT),
> +	EVENT_ATTR(read_hit,			L3_EVENT_READ_HIT),
> +	NULL,
> +};
> +
> +static struct attribute *dmc_pmu_events_attrs[] = {
> +	EVENT_ATTR(cnt_cycles,			DMC_EVENT_COUNT_CYCLES),
> +	EVENT_ATTR(write_txns,			DMC_EVENT_WRITE_TXNS),
> +	EVENT_ATTR(data_transfers,		DMC_EVENT_DATA_TRANSFERS),
> +	EVENT_ATTR(read_txns,			DMC_EVENT_READ_TXNS),
> +	NULL,
> +};
> +
> +static const struct attribute_group l3c_pmu_events_attr_group = {
> +	.name = "events",
> +	.attrs = l3c_pmu_events_attrs,
> +};
> +
> +static const struct attribute_group dmc_pmu_events_attr_group = {
> +	.name = "events",
> +	.attrs = dmc_pmu_events_attrs,
> +};
> +
> +/*
> + * sysfs cpumask attributes
> + */
> +static ssize_t cpumask_show(struct device *dev, struct device_attribute
> +		*attr, char *buf)

nit: Coding style issues. Please don't split the parameter definition.
Also check the alignment.


> +{
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	tx2_pmu = pmu_to_tx2_pmu(dev_get_drvdata(dev));
> +	return cpumap_print_to_pagebuf(true, buf, cpumask_of(tx2_pmu->cpu));
> +}
> +static DEVICE_ATTR_RO(cpumask);
> +
> +static struct attribute *tx2_pmu_cpumask_attrs[] = {
> +	&dev_attr_cpumask.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group pmu_cpumask_attr_group = {
> +	.attrs = tx2_pmu_cpumask_attrs,
> +};
> +
> +/*
> + * Per PMU device attribute groups
> + */
> +static const struct attribute_group *l3c_pmu_attr_groups[] = {
> +	&l3c_pmu_format_attr_group,
> +	&pmu_cpumask_attr_group,
> +	&l3c_pmu_events_attr_group,
> +	NULL
> +};
> +
> +static const struct attribute_group *dmc_pmu_attr_groups[] = {
> +	&dmc_pmu_format_attr_group,
> +	&pmu_cpumask_attr_group,
> +	&dmc_pmu_events_attr_group,
> +	NULL
> +};
> +
> +static inline u32 reg_readl(unsigned long addr)
> +{
> +	return readl((void __iomem *)addr);
> +}
> +
> +static inline void reg_writel(u32 val, unsigned long addr)
> +{
> +	writel(val, (void __iomem *)addr);
> +}
> +
> +static int alloc_counter(struct tx2_uncore_pmu *tx2_pmu)
> +{
> +	int counter;
> +
> +	counter = find_first_zero_bit(tx2_pmu->active_counters,
> +				tx2_pmu->max_counters);
> +	if (counter == tx2_pmu->max_counters)
> +		return -ENOSPC;
> +
> +	set_bit(counter, tx2_pmu->active_counters);
> +	return counter;
> +}
> +
> +static inline void free_counter(struct tx2_uncore_pmu *tx2_pmu, int counter)
> +{
> +	clear_bit(counter, tx2_pmu->active_counters);
> +}
> +
> +static void init_cntr_base_l3c(struct perf_event *event,
> +		struct tx2_uncore_pmu *tx2_pmu)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	/* counter ctrl/data reg offset at 8 */
> +	hwc->config_base = (unsigned long)tx2_pmu->base
> +		+ L3C_COUNTER_CTL + (8 * GET_COUNTERID(event));
> +	hwc->event_base =  (unsigned long)tx2_pmu->base
> +		+ L3C_COUNTER_DATA + (8 * GET_COUNTERID(event));
> +}
> +
> +static void init_cntr_base_dmc(struct perf_event *event,
> +		struct tx2_uncore_pmu *tx2_pmu)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	hwc->config_base = (unsigned long)tx2_pmu->base
> +		+ DMC_COUNTER_CTL;
> +	/* counter data reg offset at 0xc */
> +	hwc->event_base = (unsigned long)tx2_pmu->base
> +		+ DMC_COUNTER_DATA + (0xc * GET_COUNTERID(event));
> +}
> +
> +static void uncore_start_event_l3c(struct perf_event *event, int flags)
> +{
> +	u32 val;
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	/* event id encoded in bits [07:03] */
> +	val = GET_EVENTID(event) << 3;
> +	reg_writel(val, hwc->config_base);
> +	local64_set(&hwc->prev_count, 0);
> +	reg_writel(0, hwc->event_base);
> +}
> +
> +static inline void uncore_stop_event_l3c(struct perf_event *event)
> +{
> +	reg_writel(0, event->hw.config_base);
> +}
> +
> +static void uncore_start_event_dmc(struct perf_event *event, int flags)
> +{
> +	u32 val;
> +	struct hw_perf_event *hwc = &event->hw;
> +	int idx = GET_COUNTERID(event);
> +	int event_id = GET_EVENTID(event);
> +
> +	/* enable and start counters.
> +	 * 8 bits for each counter, bits[05:01] of a counter to set event type.
> +	 */
> +	val = reg_readl(hwc->config_base);
> +	val &= ~DMC_EVENT_CFG(idx, 0x1f);
> +	val |= DMC_EVENT_CFG(idx, event_id);
> +	reg_writel(val, hwc->config_base);
> +	local64_set(&hwc->prev_count, 0);
> +	reg_writel(0, hwc->event_base);
> +}
> +
> +static void uncore_stop_event_dmc(struct perf_event *event)
> +{
> +	u32 val;
> +	struct hw_perf_event *hwc = &event->hw;
> +	int idx = GET_COUNTERID(event);
> +
> +	/* clear event type(bits[05:01]) to stop counter */
> +	val = reg_readl(hwc->config_base);
> +	val &= ~DMC_EVENT_CFG(idx, 0x1f);
> +	reg_writel(val, hwc->config_base);
> +}
> +
> +static void tx2_uncore_event_update(struct perf_event *event)
> +{
> +	s64 prev, delta, new = 0;
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +	enum tx2_uncore_type type;
> +	u32    prorate_factor;
> +
> +	tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +	type = tx2_pmu->type;
> +	prorate_factor = tx2_pmu->prorate_factor;
> +
> +	new = reg_readl(hwc->event_base);
> +	prev = local64_xchg(&hwc->prev_count, new);
> +
> +	/* handles rollover of 32 bit counter */
> +	delta = (u32)(((1UL << 32) - prev) + new);
> +
> +	/* DMC event data_transfers granularity is 16 Bytes, convert it to 64 */
> +	if (type == PMU_TYPE_DMC &&
> +			GET_EVENTID(event) == DMC_EVENT_DATA_TRANSFERS)
> +		delta = delta/4;
> +
> +	/* L3C and DMC has 16 and 8 interleave channels respectively.
> +	 * The sampled value is for channel 0 and multiplied with
> +	 * prorate_factor to get the count for a device.
> +	 */
> +	local64_add(delta * prorate_factor, &event->count);
> +}
> +
> +enum tx2_uncore_type get_tx2_pmu_type(struct acpi_device *adev)
> +{
> +	int i = 0;
> +	struct acpi_tx2_pmu_device {
> +		__u8 id[ACPI_ID_LEN];
> +		enum tx2_uncore_type type;
> +	} devices[] = {
> +		{"CAV901D", PMU_TYPE_L3C},
> +		{"CAV901F", PMU_TYPE_DMC},
> +		{"", PMU_TYPE_INVALID}
> +	};
> +
> +	while (devices[i].type != PMU_TYPE_INVALID) {
> +		if (!strcmp(acpi_device_hid(adev), devices[i].id))
> +			return devices[i].type;
> +		i++;
> +	}
> +	return PMU_TYPE_INVALID;

minor nit: The above could be folded to :

	while (devices[i].type != PMU_TYPE_INVALID) {
		if (!strcmp(acpi_device_hid(adev), devices[i].id))
			break;
		i++;
	}

	return devices[i].type;

> +}
> +
> +static bool tx2_uncore_validate_event(struct pmu *pmu,
> +				  struct perf_event *event, int *counters)
> +{
> +	if (is_software_event(event))
> +		return true;
> +	/* Reject groups spanning multiple HW PMUs. */
> +	if (event->pmu != pmu)
> +		return false;
> +
> +	*counters = *counters + 1;
> +		return true;
> +}
> +
> +/*
> + * Make sure the group of events can be scheduled at once
> + * on the PMU.
> + */
> +static bool tx2_uncore_validate_event_group(struct perf_event *event)
> +{
> +	struct perf_event *sibling, *leader = event->group_leader;
> +	int counters = 0;
> +
> +	if (event->group_leader == event)
> +		return true;
> +
> +	if (!tx2_uncore_validate_event(event->pmu, leader, &counters))
> +		return false;
> +
> +	for_each_sibling_event(sibling, leader) {
> +		if (!tx2_uncore_validate_event(event->pmu, sibling, &counters))
> +			return false;
> +	}
> +
> +	if (!tx2_uncore_validate_event(event->pmu, event, &counters))
> +		return false;
> +
> +	/*
> +	 * If the group requires more counters than the HW has,
> +	 * it cannot ever be scheduled.
> +	 */
> +	return counters <= TX2_PMU_MAX_COUNTERS;
> +}
> +
> +
> +static int tx2_uncore_event_init(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	/* Test the event attr type check for PMU enumeration */
> +	if (event->attr.type != event->pmu->type)
> +		return -ENOENT;
> +
> +	/*
> +	 * SOC PMU counters are shared across all cores.
> +	 * Therefore, it does not support per-process mode.
> +	 * Also, it does not support event sampling mode.
> +	 */
> +	if (is_sampling_event(event) || event->attach_state & PERF_ATTACH_TASK)
> +		return -EINVAL;
> +
> +	/* SOC counters do not have usr/os/guest/host bits */
> +	if (event->attr.exclude_user || event->attr.exclude_kernel ||
> +	    event->attr.exclude_host || event->attr.exclude_guest)

exclude_hv and exclude_idle missing ?

> +		return -EINVAL;
> +
> +	if (event->cpu < 0)
> +		return -EINVAL;
> +
> +	tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +	if (tx2_pmu->cpu >= nr_cpu_ids)
> +		return -EINVAL;
> +	event->cpu = tx2_pmu->cpu;
> +
> +	if (event->attr.config >= tx2_pmu->max_events)
> +		return -EINVAL;
> +
> +	/* store event id */
> +	hwc->config = event->attr.config > +
> +	/* Validate the group */
> +	if (!tx2_uncore_validate_event_group(event))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void tx2_uncore_event_start(struct perf_event *event, int flags)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	hwc->state = 0;
> +	tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +
> +	tx2_pmu->start_event(event, flags);
> +	perf_event_update_userpage(event);
> +
> +	/* Start timer for first event */
> +	if (bitmap_weight(tx2_pmu->active_counters,
> +				tx2_pmu->max_counters) == 1) {
> +		hrtimer_start(&tx2_pmu->hrtimer,
> +			ns_to_ktime(tx2_pmu->hrtimer_interval),
> +			HRTIMER_MODE_REL_PINNED);
> +	}
> +}
> +
> +static void tx2_uncore_event_stop(struct perf_event *event, int flags)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	if (hwc->state & PERF_HES_UPTODATE)
> +		return;
> +
> +	tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +	tx2_pmu->stop_event(event);
> +	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
> +	hwc->state |= PERF_HES_STOPPED;
> +	if (flags & PERF_EF_UPDATE) {
> +		tx2_uncore_event_update(event);
> +		hwc->state |= PERF_HES_UPTODATE;
> +	}
> +}
> +
> +static int tx2_uncore_event_add(struct perf_event *event, int flags)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +
> +	/* Allocate a free counter */
> +	hwc->idx  = alloc_counter(tx2_pmu);
> +	if (hwc->idx < 0)
> +		return -EAGAIN;
> +
> +	tx2_pmu->events[hwc->idx] = event;
> +	/* set counter control and data registers base address */
> +	tx2_pmu->init_cntr_base(event, tx2_pmu);
> +
> +	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
> +	if (flags & PERF_EF_START)
> +		tx2_uncore_event_start(event, flags);
> +
> +	return 0;
> +}
> +
> +static void tx2_uncore_event_del(struct perf_event *event, int flags)
> +{
> +	struct tx2_uncore_pmu *tx2_pmu = pmu_to_tx2_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	tx2_uncore_event_stop(event, PERF_EF_UPDATE);
> +
> +	/* clear the assigned counter */
> +	free_counter(tx2_pmu, GET_COUNTERID(event));
> +
> +	perf_event_update_userpage(event);
> +	tx2_pmu->events[hwc->idx] = NULL;
> +	hwc->idx = -1;
> +}
> +
> +static void tx2_uncore_event_read(struct perf_event *event)
> +{
> +	tx2_uncore_event_update(event);
> +}
> +
> +static enum hrtimer_restart tx2_hrtimer_callback(struct hrtimer *timer)
> +{
> +	struct tx2_uncore_pmu *tx2_pmu;
> +	int max_counters, idx;
> +	unsigned long irqflags;
> +
> +	tx2_pmu = container_of(timer, struct tx2_uncore_pmu, hrtimer);
> +	max_counters = tx2_pmu->max_counters;
> +
> +	if (bitmap_empty(tx2_pmu->active_counters, max_counters))
> +		return HRTIMER_NORESTART;
> +
> +	raw_spin_lock_irqsave(&tx2_pmu->lock, irqflags);
> +
> +	for_each_set_bit(idx, tx2_pmu->active_counters, max_counters) {
> +		struct perf_event *event = tx2_pmu->events[idx];
> +
> +		tx2_uncore_event_update(event);
> +	}
> +	raw_spin_unlock_irqrestore(&tx2_pmu->lock, irqflags);

What does this lock protect ? Can there be multiple active hrtimers for 
the same PMU ?

> +	hrtimer_forward_now(timer, ns_to_ktime(tx2_pmu->hrtimer_interval));
> +	return HRTIMER_RESTART;
> +}
> +
> +static int tx2_uncore_pmu_register(
> +		struct tx2_uncore_pmu *tx2_pmu)
> +{
> +	struct device *dev = tx2_pmu->dev;
> +	char *name = tx2_pmu->name;
> +
> +	/* Perf event registration */
> +	tx2_pmu->pmu = (struct pmu) {
> +		.module         = THIS_MODULE,
> +		.attr_groups	= tx2_pmu->attr_groups,
> +		.task_ctx_nr	= perf_invalid_context,
> +		.event_init	= tx2_uncore_event_init,
> +		.add		= tx2_uncore_event_add,
> +		.del		= tx2_uncore_event_del,
> +		.start		= tx2_uncore_event_start,
> +		.stop		= tx2_uncore_event_stop,
> +		.read		= tx2_uncore_event_read,
> +	};
> +
> +	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
> +			"%s", name);
> +
> +	return perf_pmu_register(&tx2_pmu->pmu, tx2_pmu->pmu.name, -1);
> +}
> +
> +static int tx2_uncore_pmu_add_dev(struct tx2_uncore_pmu *tx2_pmu)
> +{
> +	int ret, cpu;
> +
> +	cpu = cpumask_any_and(cpumask_of_node(tx2_pmu->node),
> +			cpu_online_mask);
> +
> +	tx2_pmu->cpu = cpu;
> +	hrtimer_init(&tx2_pmu->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +	tx2_pmu->hrtimer.function = tx2_hrtimer_callback;
> +
> +	ret = tx2_uncore_pmu_register(tx2_pmu);
> +	if (ret) {
> +		dev_err(tx2_pmu->dev, "%s PMU: Failed to init driver\n",
> +				tx2_pmu->name);
> +		return -ENODEV;
> +	}
> +
> +	/* register hotplug callback for the pmu */
> +	ret = cpuhp_state_add_instance(
> +			CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE,
> +			&tx2_pmu->hpnode);
> +	if (ret) {
> +		dev_err(tx2_pmu->dev, "Error %d registering hotplug", ret);
> +		return ret;
> +	}
> +
> +	/* Add to list */
> +	list_add(&tx2_pmu->entry, &tx2_pmus);
> +
> +	dev_dbg(tx2_pmu->dev, "%s PMU UNCORE registered\n",
> +			tx2_pmu->pmu.name);
> +	return ret;
> +}
> +
> +static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
> +		acpi_handle handle, struct acpi_device *adev, u32 type)
> +{
> +	struct tx2_uncore_pmu *tx2_pmu;
> +	void __iomem *base;
> +	struct resource res;
> +	struct resource_entry *rentry;
> +	struct list_head list;
> +	int ret;
> +
> +	INIT_LIST_HEAD(&list);
> +	ret = acpi_dev_get_resources(adev, &list, NULL, NULL);
> +	if (ret <= 0) {
> +		dev_err(dev, "failed to parse _CRS method, error %d\n", ret);
> +		return NULL;
> +	}
> +
> +	list_for_each_entry(rentry, &list, node) {
> +		if (resource_type(rentry->res) == IORESOURCE_MEM) {
> +			res = *rentry->res;
> +			break;
> +		}
> +	}
> +
> +	if (!rentry->res)
> +		return NULL;
> +
> +	acpi_dev_free_resource_list(&list);
> +	base = devm_ioremap_resource(dev, &res);
> +	if (IS_ERR(base)) {
> +		dev_err(dev, "PMU type %d: Fail to map resource\n", type);
> +		return NULL;
> +	}
> +
> +	tx2_pmu = devm_kzalloc(dev, sizeof(*tx2_pmu), GFP_KERNEL);
> +	if (!tx2_pmu)
> +		return NULL;
> +
> +	tx2_pmu->dev = dev;
> +	tx2_pmu->type = type;
> +	tx2_pmu->base = base;
> +	tx2_pmu->node = dev_to_node(dev);
> +	INIT_LIST_HEAD(&tx2_pmu->entry);
> +	raw_spin_lock_init(&tx2_pmu->lock);
> +
> +	switch (tx2_pmu->type) {
> +	case PMU_TYPE_L3C:
> +		tx2_pmu->max_counters = TX2_PMU_MAX_COUNTERS;
> +		tx2_pmu->prorate_factor = TX2_PMU_L3_TILES;
> +		tx2_pmu->max_events = L3_EVENT_MAX;
> +		tx2_pmu->hrtimer_interval = TX2_PMU_HRTIMER_INTERVAL;
> +		tx2_pmu->attr_groups = l3c_pmu_attr_groups;
> +		tx2_pmu->name = devm_kasprintf(dev, GFP_KERNEL,
> +				"uncore_l3c_%d", tx2_pmu->node);
> +		tx2_pmu->init_cntr_base = init_cntr_base_l3c;
> +		tx2_pmu->start_event = uncore_start_event_l3c;
> +		tx2_pmu->stop_event = uncore_stop_event_l3c;
> +		break;
> +	case PMU_TYPE_DMC:
> +		tx2_pmu->max_counters = TX2_PMU_MAX_COUNTERS;
> +		tx2_pmu->prorate_factor = TX2_PMU_DMC_CHANNELS;
> +		tx2_pmu->max_events = DMC_EVENT_MAX;
> +		tx2_pmu->hrtimer_interval = TX2_PMU_HRTIMER_INTERVAL;
> +		tx2_pmu->attr_groups = dmc_pmu_attr_groups;
> +		tx2_pmu->name = devm_kasprintf(dev, GFP_KERNEL,
> +				"uncore_dmc_%d", tx2_pmu->node);
> +		tx2_pmu->init_cntr_base = init_cntr_base_dmc;
> +		tx2_pmu->start_event = uncore_start_event_dmc;
> +		tx2_pmu->stop_event = uncore_stop_event_dmc;
> +		break;
> +	case PMU_TYPE_INVALID:
> +		devm_kfree(dev, tx2_pmu);
> +		return NULL;
> +	}
> +
> +	return tx2_pmu;
> +}
> +
> +static int tx2_uncore_pmu_online_cpu(unsigned int cpu,
> +		struct hlist_node *hpnode)
> +{
> +	struct tx2_uncore_pmu *tx2_pmu;
> +
> +	tx2_pmu = hlist_entry_safe(hpnode,
> +			struct tx2_uncore_pmu, hpnode);
> +
> +	/* Pick this CPU, If there is no CPU/PMU association and both are
> +	 * from same node.
> +	 */
> +	if ((tx2_pmu->cpu >= nr_cpu_ids) &&
> +		(tx2_pmu->node == cpu_to_node(cpu)))
> +		tx2_pmu->cpu = cpu;
> +
> +	return 0;
> +}
> +
> +static int tx2_uncore_pmu_offline_cpu(unsigned int cpu,
> +		struct hlist_node *hpnode)
> +{
> +	int new_cpu;
> +	struct tx2_uncore_pmu *tx2_pmu;
> +	struct cpumask cpu_online_mask_temp;
> +
> +	tx2_pmu = hlist_entry_safe(hpnode,
> +			struct tx2_uncore_pmu, hpnode);
> +
> +	if (cpu != tx2_pmu->cpu)
> +		return 0;
> +
> +	hrtimer_cancel(&tx2_pmu->hrtimer);
> +	cpumask_copy(&cpu_online_mask_temp, cpu_online_mask);
> +	cpumask_clear_cpu(cpu, &cpu_online_mask_temp);
> +	new_cpu = cpumask_any_and(
> +			cpumask_of_node(tx2_pmu->node),
> +			&cpu_online_mask_temp);
> +
> +	tx2_pmu->cpu = new_cpu;
> +	if (new_cpu >= nr_cpu_ids)
> +		return 0;
> +	perf_pmu_migrate_context(&tx2_pmu->pmu, cpu, new_cpu);
> +
> +	return 0;
> +}
> +
> +static const struct acpi_device_id tx2_uncore_acpi_match[] = {
> +	{"CAV901C", 0},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(acpi, tx2_uncore_acpi_match);
> +
> +static int tx2_uncore_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	acpi_handle handle;
> +	acpi_status status;
> +
> +	set_dev_node(dev, acpi_get_node(ACPI_HANDLE(dev)));
> +
> +	if (!has_acpi_companion(dev))
> +		return -ENODEV;
> +
> +	handle = ACPI_HANDLE(dev);
> +	if (!handle)
> +		return -EINVAL;
> +
> +	/* Walk through the tree for all PMU UNCORE devices */
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> +				     tx2_uncore_pmu_add,
> +				     NULL, dev, NULL);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev, "failed to probe PMU devices\n");
> +		return_ACPI_STATUS(status);
> +	}
> +
> +	dev_info(dev, "node%d: pmu uncore registered\n", dev_to_node(dev));
> +	return 0;
> +}
> +
> +static int tx2_uncore_remove(struct platform_device *pdev)
> +{
> +	struct tx2_uncore_pmu *tx2_pmu, *temp;
> +	struct device *dev = &pdev->dev;
> +
> +	if (!list_empty(&tx2_pmus)) {
> +		list_for_each_entry_safe(tx2_pmu, temp, &tx2_pmus, entry) {
> +			if (tx2_pmu->node == dev_to_node(dev)) {
> +				cpuhp_state_remove_instance_nocalls(
> +					CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE,
> +					&tx2_pmu->hpnode);
> +				perf_pmu_unregister(&tx2_pmu->pmu);
> +				list_del(&tx2_pmu->entry);
> +			}
> +		}
> +	}
> +	return 0;
> +}
> +
> +static struct platform_driver tx2_uncore_driver = {
> +	.driver = {
> +		.name		= "tx2-uncore-pmu",
> +		.acpi_match_table = ACPI_PTR(tx2_uncore_acpi_match),
> +	},
> +	.probe = tx2_uncore_probe,
> +	.remove = tx2_uncore_remove,
> +};
> +
> +static int __init tx2_uncore_driver_init(void)
> +{
> +	int ret;
> +
> +	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE,
> +				      "perf/tx2/uncore:online",
> +				      tx2_uncore_pmu_online_cpu,
> +				      tx2_uncore_pmu_offline_cpu);
> +	if (ret) {
> +		pr_err("TX2 PMU: setup hotplug failed(%d)\n", ret);
> +		return ret;
> +	}
> +	ret = platform_driver_register(&tx2_uncore_driver);
> +	if (ret)
> +		cpuhp_remove_multi_state(CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE);
> +
> +	return ret;
> +}
> +module_init(tx2_uncore_driver_init);
> +
> +static void __exit tx2_uncore_driver_exit(void)
> +{
> +	platform_driver_unregister(&tx2_uncore_driver);
> +	cpuhp_remove_multi_state(CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE);
> +}
> +module_exit(tx2_uncore_driver_exit);
> +
> +MODULE_DESCRIPTION("ThunderX2 UNCORE PMU driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Ganapatrao Kulkarni <gkulkarni@...ium.com>");
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index caf40ad0bbc6..2c13dc2f765d 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -163,6 +163,7 @@ enum cpuhp_state {
>   	CPUHP_AP_PERF_ARM_L2X0_ONLINE,
>   	CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
>   	CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
> +	CPUHP_AP_PERF_ARM_TX2_UNCORE_ONLINE,
>   	CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
>   	CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
>   	CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
> 

Suzuki

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