Message-ID: <c4e9c893-9130-7024-e24e-c63e232be4be@huawei.com>
Date:   Wed, 18 Aug 2021 14:49:28 +0100
From:   John Garry <john.garry@...wei.com>
To:     Bharat Bhushan <bbhushan2@...vell.com>, <will@...nel.org>,
        <mark.rutland@....com>, <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] perf/marvell: CN10k DDR performance monitor
 support

On 10/08/2021 10:43, Bharat Bhushan wrote:
> Marvell CN10k DRAM Subsystem (DSS) supports eight
> event counters for monitoring performance and software
> can program each counter to monitor any of the defined
> performance event. Performance events are for interface
> between the DDR controller and the PHY, interface between
> the DDR Controller and the CHI interconnect, or within
> the DDR Controller. Additionally DSS also supports two
> fixed performance event counters, one for number of
> ddr reads and other for ddr writes.
> 
> This patch add basic support for these performance
> monitoring events on CN10k.

please use full 75 char width

> 
> Signed-off-by: Bharat Bhushan <bbhushan2@...vell.com>
> ---
> v1->v2:
>   - writeq/readq changed to respective relaxed version
>   - Using PMU_EVENT_ATTR_ID
> 
>   drivers/perf/Kconfig                 |   7 +
>   drivers/perf/Makefile                |   1 +
>   drivers/perf/marvell_cn10k_ddr_pmu.c | 606 +++++++++++++++++++++++++++
>   3 files changed, 614 insertions(+)
>   create mode 100644 drivers/perf/marvell_cn10k_ddr_pmu.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 77522e5efe11..41a80a4b8d29 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -139,4 +139,11 @@ config ARM_DMC620_PMU
>   
>   source "drivers/perf/hisilicon/Kconfig"
>   
> +config MARVELL_CN10K_DDR_PMU
> +	tristate "Enable MARVELL CN10K DRAM Subsystem(DSS) PMU Support"
> +	depends on ARM64

Is there anything to stop using adding COMPILE_TEST as a dependency? 
This really helps build coverage testing for other archs

> +	help
> +	  Enable perf support for Marvell DDR Performance monitoring
> +	  event on CN10K platform.
> +
>   endmenu
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index 5260b116c7da..ee1126219d8d 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -14,3 +14,4 @@ obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
>   obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
>   obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
>   obj-$(CONFIG_ARM_DMC620_PMU) += arm_dmc620_pmu.o
> +obj-$(CONFIG_MARVELL_CN10K_DDR_PMU) += marvell_cn10k_ddr_pmu.o
> diff --git a/drivers/perf/marvell_cn10k_ddr_pmu.c b/drivers/perf/marvell_cn10k_ddr_pmu.c
> new file mode 100644
> index 000000000000..8f9e3d1fcd8d
> --- /dev/null
> +++ b/drivers/perf/marvell_cn10k_ddr_pmu.c
> @@ -0,0 +1,606 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Marvell CN10K DRAM Subsystem (DSS) Performance Monitor Driver
> + *
> + * Copyright (C) 2021 Marvell.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/perf_event.h>
> +
> +/* Performance Counters Operating Mode Control Registers */
> +#define DDRC_PERF_CNT_OP_MODE_CTRL	0x8020
> +#define OP_MODE_CTRL_VAL_MANNUAL	0x1
> +
> +/* Performance Counters Start Operation Control Registers */
> +#define DDRC_PERF_CNT_START_OP_CTRL	0x8028
> +#define START_OP_CTRL_VAL_START		0x1ULL
> +#define START_OP_CTRL_VAL_ACTIVE	0x2
> +
> +/* Performance Counters End Operation Control Registers */
> +#define DDRC_PERF_CNT_END_OP_CTRL	0x8030
> +#define END_OP_CTRL_VAL_END		0x1ULL
> +
> +/* Performance Counters End Status Registers */
> +#define DDRC_PERF_CNT_END_STATUS		0x8038
> +#define END_STATUS_VAL_END_TIMER_MODE_END	0x1
> +
> +/* Performance Counters Configuration Registers */
> +#define DDRC_PERF_CFG_BASE		0x8040
> +
> +/* 8 Generic event counter + 2 fixed event counters */
> +#define DDRC_PERF_NUM_GEN_COUNTERS	8
> +#define DDRC_PERF_NUM_FIX_COUNTERS	2
> +#define DDRC_PERF_READ_COUNTER_IDX	DDRC_PERF_NUM_GEN_COUNTERS
> +#define DDRC_PERF_WRITE_COUNTER_IDX	(DDRC_PERF_NUM_GEN_COUNTERS + 1)
> +#define DDRC_PERF_NUM_COUNTERS		(DDRC_PERF_NUM_GEN_COUNTERS + \
> +					 DDRC_PERF_NUM_FIX_COUNTERS)
> +
> +/* Generic event counter registers */
> +#define DDRC_PERF_CFG(n)		(DDRC_PERF_CFG_BASE + 8 * (n))
> +#define EVENT_ENABLE			BIT_ULL(63)
> +
> +/* Two dedicated event counters for DDR reads and writes */
> +#define EVENT_DDR_READS			101
> +#define EVENT_DDR_WRITES		100
> +
> +/*
> + * programmable events IDs in programmable event counters.
> + * DO NOT change these event-id numbers, they are used to
> + * program event bitmap in h/w.
> + */
> +#define EVENT_OP_IS_ZQLATCH			55
> +#define EVENT_OP_IS_ZQSTART			54
> +#define EVENT_OP_IS_TCR_MRR			53
> +#define EVENT_OP_IS_DQSOSC_MRR			52
> +#define EVENT_OP_IS_DQSOSC_MPC			51
> +#define EVENT_VISIBLE_WIN_LIMIT_REACHED_WR	50
> +#define EVENT_VISIBLE_WIN_LIMIT_REACHED_RD	49
> +#define EVENT_BSM_STARVATION			48
> +#define EVENT_BSM_ALLOC				47
> +#define EVENT_LPR_REQ_WITH_NOCREDIT		46
> +#define EVENT_HPR_REQ_WITH_NOCREDIT		45
> +#define EVENT_OP_IS_ZQCS			44
> +#define EVENT_OP_IS_ZQCL			43
> +#define EVENT_OP_IS_LOAD_MODE			42
> +#define EVENT_OP_IS_SPEC_REF			41
> +#define EVENT_OP_IS_CRIT_REF			40
> +#define EVENT_OP_IS_REFRESH			39
> +#define EVENT_OP_IS_ENTER_MPSM			35
> +#define EVENT_OP_IS_ENTER_POWERDOWN		31
> +#define EVENT_OP_IS_ENTER_SELFREF		27
> +#define EVENT_WAW_HAZARD			26
> +#define EVENT_RAW_HAZARD			25
> +#define EVENT_WAR_HAZARD			24
> +#define EVENT_WRITE_COMBINE			23
> +#define EVENT_RDWR_TRANSITIONS			22
> +#define EVENT_PRECHARGE_FOR_OTHER		21
> +#define EVENT_PRECHARGE_FOR_RDWR		20
> +#define EVENT_OP_IS_PRECHARGE			19
> +#define EVENT_OP_IS_MWR				18
> +#define EVENT_OP_IS_WR				17
> +#define EVENT_OP_IS_RD				16
> +#define EVENT_OP_IS_RD_ACTIVATE			15
> +#define EVENT_OP_IS_RD_OR_WR			14
> +#define EVENT_OP_IS_ACTIVATE			13
> +#define EVENT_WR_XACT_WHEN_CRITICAL		12
> +#define EVENT_LPR_XACT_WHEN_CRITICAL		11
> +#define EVENT_HPR_XACT_WHEN_CRITICAL		10
> +#define EVENT_DFI_RD_DATA_CYCLES		9
> +#define EVENT_DFI_WR_DATA_CYCLES		8
> +#define EVENT_ACT_BYPASS			7
> +#define EVENT_READ_BYPASS			6
> +#define EVENT_HIF_HI_PRI_RD			5
> +#define EVENT_HIF_RMW				4
> +#define EVENT_HIF_RD				3
> +#define EVENT_HIF_WR				2
> +#define EVENT_HIF_RD_OR_WR			1
> +
> +/* Event counter value registers */
> +#define DDRC_PERF_CNT_VALUE_BASE		0x8080
> +#define DDRC_PERF_CNT_VALUE(n)	(DDRC_PERF_CNT_VALUE_BASE + 8 * (n))
> +
> +/* Fixed event counter enable/disable register */
> +#define DDRC_PERF_CNT_FREERUN_EN	0x80C0
> +#define DDRC_PERF_FREERUN_WRITE_EN	0x1
> +#define DDRC_PERF_FREERUN_READ_EN	0x2
> +
> +/* Fixed event counter control register */
> +#define DDRC_PERF_CNT_FREERUN_CTRL	0x80C8
> +#define DDRC_FREERUN_WRITE_CNT_CLR	0x1
> +#define DDRC_FREERUN_READ_CNT_CLR	0x2
> +
> +/* Fixed event counter value register */
> +#define DDRC_PERF_CNT_VALUE_WR_OP	0x80D0
> +#define DDRC_PERF_CNT_VALUE_RD_OP	0x80D8
> +#define DDRC_PERF_CNT_VALUE_OVERFLOW	BIT_ULL(48)
> +#define DDRC_PERF_CNT_MAX_VALUE		GENMASK_ULL(48, 0)

I assume all these macros are used...

> +
> +struct cn10k_ddr_pmu {
> +	struct pmu pmu;
> +	int id;
> +	void __iomem *base;
> +	unsigned int cpu;
> +	struct	device *dev;
> +	int active_events;
> +	struct perf_event *events[DDRC_PERF_NUM_COUNTERS];
> +};
> +
> +#define to_cn10k_ddr_pmu(p)	container_of(p, struct cn10k_ddr_pmu, pmu)
> +
> +static ssize_t cn10k_ddr_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);

isn't sysfs_emit() preferred now? Need to check.

> +}
> +
> +#define CN10K_DDR_PMU_EVENT_ATTR(_name, _id)				     \
> +	PMU_EVENT_ATTR_ID(_name, cn10k_ddr_pmu_event_show, _id)
> +
> +static struct attribute *cn10k_ddr_perf_events_attrs[] = {
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hif_rd_or_wr_access, EVENT_HIF_RD_OR_WR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hif_wr_access, EVENT_HIF_WR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hif_rd_access, EVENT_HIF_RD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hif_rmw_access, EVENT_HIF_RMW),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hif_pri_rdaccess, EVENT_HIF_HI_PRI_RD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_rd_bypass_access, EVENT_READ_BYPASS),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_act_bypass_access, EVENT_ACT_BYPASS),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_dif_wr_data_access, EVENT_DFI_WR_DATA_CYCLES),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_dif_rd_data_access, EVENT_DFI_RD_DATA_CYCLES),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hpri_sched_rd_crit_access,
> +					EVENT_HPR_XACT_WHEN_CRITICAL),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_lpri_sched_rd_crit_access,
> +					EVENT_LPR_XACT_WHEN_CRITICAL),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_wr_trxn_crit_access,
> +					EVENT_WR_XACT_WHEN_CRITICAL),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_active_access, EVENT_OP_IS_ACTIVATE),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_rd_or_wr_access, EVENT_OP_IS_RD_OR_WR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_rd_active_access, EVENT_OP_IS_RD_ACTIVATE),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_read, EVENT_OP_IS_RD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_write, EVENT_OP_IS_WR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_mwr, EVENT_OP_IS_MWR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_precharge, EVENT_OP_IS_PRECHARGE),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_precharge_for_rdwr, EVENT_PRECHARGE_FOR_RDWR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_precharge_for_other,
> +					EVENT_PRECHARGE_FOR_OTHER),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_rdwr_transitions, EVENT_RDWR_TRANSITIONS),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_write_combine, EVENT_WRITE_COMBINE),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_war_hazard, EVENT_WAR_HAZARD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_raw_hazard, EVENT_RAW_HAZARD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_waw_hazard, EVENT_WAW_HAZARD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_enter_selfref, EVENT_OP_IS_ENTER_SELFREF),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_enter_powerdown, EVENT_OP_IS_ENTER_POWERDOWN),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_enter_mpsm, EVENT_OP_IS_ENTER_MPSM),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_refresh, EVENT_OP_IS_REFRESH),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_crit_ref, EVENT_OP_IS_CRIT_REF),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_spec_ref, EVENT_OP_IS_SPEC_REF),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_load_mode, EVENT_OP_IS_LOAD_MODE),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_zqcl, EVENT_OP_IS_ZQCL),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_cam_wr_access, EVENT_OP_IS_ZQCS),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_hpr_req_with_nocredit,
> +					EVENT_HPR_REQ_WITH_NOCREDIT),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_lpr_req_with_nocredit,
> +					EVENT_LPR_REQ_WITH_NOCREDIT),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_bsm_alloc, EVENT_BSM_ALLOC),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_bsm_starvation, EVENT_BSM_STARVATION),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_win_limit_reached_rd,
> +					EVENT_VISIBLE_WIN_LIMIT_REACHED_RD),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_win_limit_reached_wr,
> +					EVENT_VISIBLE_WIN_LIMIT_REACHED_WR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_dqsosc_mpc, EVENT_OP_IS_DQSOSC_MPC),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_dqsosc_mrr, EVENT_OP_IS_DQSOSC_MRR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_tcr_mrr, EVENT_OP_IS_TCR_MRR),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_zqstart, EVENT_OP_IS_ZQSTART),
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_zqlatch, EVENT_OP_IS_ZQLATCH),
> +	/* Free run event counters */
> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_ddr_reads, EVENT_DDR_READS),

if you want perf tool to support aliases / metrics for these then a hw 
identifer sysfs file is required, like the freescale imx8 ddr pmu driver 
has, as I assume that this PMU is not tightly coupled always to a 
specific CPU

> +	CN10K_DDR_PMU_EVENT_ATTR(ddr_ddr_writes, EVENT_DDR_WRITES),
> +	NULL,

no need for ',' when the array is not going to be expanded

> +};
> +
> +static struct attribute_group cn10k_ddr_perf_events_attr_group = {
> +	.name = "events",
> +	.attrs = cn10k_ddr_perf_events_attrs,
> +};
> +
> +PMU_FORMAT_ATTR(event, "config:0-8");
> +
> +static struct attribute *cn10k_ddr_perf_format_attrs[] = {
> +	&format_attr_event.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group cn10k_ddr_perf_format_attr_group = {
> +	.name = "format",
> +	.attrs = cn10k_ddr_perf_format_attrs,
> +};
> +
> +static ssize_t cn10k_ddr_perf_cpumask_show(struct device *dev,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	struct cn10k_ddr_pmu *pmu = dev_get_drvdata(dev);
> +
> +	return cpumap_print_to_pagebuf(true, buf, cpumask_of(pmu->cpu));
> +}
> +
> +static struct device_attribute cn10k_ddr_perf_cpumask_attr =
> +	__ATTR(cpumask, 0444, cn10k_ddr_perf_cpumask_show, NULL);
> +
> +static struct attribute *cn10k_ddr_perf_cpumask_attrs[] = {
> +	&cn10k_ddr_perf_cpumask_attr.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group cn10k_ddr_perf_cpumask_attr_group = {
> +	.attrs = cn10k_ddr_perf_cpumask_attrs,
> +};
> +
> +static const struct attribute_group *cn10k_attr_groups[] = {
> +	&cn10k_ddr_perf_events_attr_group,
> +	&cn10k_ddr_perf_format_attr_group,
> +	&cn10k_ddr_perf_cpumask_attr_group,
> +	NULL,
> +};
> +
> +static uint64_t ddr_perf_get_event_bitmap(int eventid)

Don't we use u64 in kernel land as preference?

> +{
> +	uint64_t event_bitmap = 0;
> +
> +	switch (eventid) {
> +	case EVENT_HIF_RD_OR_WR ... EVENT_WAW_HAZARD:
> +	case EVENT_OP_IS_REFRESH ... EVENT_OP_IS_ZQLATCH:
> +		event_bitmap = (1ULL << (eventid - 1));
> +		break;
> +
> +	case EVENT_OP_IS_ENTER_SELFREF:
> +	case EVENT_OP_IS_ENTER_POWERDOWN:
> +	case EVENT_OP_IS_ENTER_MPSM:
> +		event_bitmap = (0xFULL << (eventid - 1));
> +		break;
> +	default:
> +		pr_err("%s Invalid eventid %d\n", __func__, eventid);

shouldn't this generate a proper error to its only caller (which can 
actually error)?

> +		break;
> +	}
> +
> +	return event_bitmap;
> +}
> +
> +static int cn10k_ddr_perf_alloc_counter(struct cn10k_ddr_pmu *pmu,
> +					struct perf_event *event)
> +{
> +	uint8_t config = event->attr.config;
> +	int i;
> +
> +	/* DDR read free-run counter index */
> +	if (config == EVENT_DDR_READS) {
> +		pmu->events[DDRC_PERF_READ_COUNTER_IDX] = event;
> +		return DDRC_PERF_READ_COUNTER_IDX;
> +	}
> +
> +	/* DDR write free-run counter index */
> +	if (config == EVENT_DDR_WRITES) {
> +		pmu->events[DDRC_PERF_WRITE_COUNTER_IDX] = event;
> +		return DDRC_PERF_WRITE_COUNTER_IDX;
> +	}
> +
> +	/* Allocate DDR generic counters */
> +	for (i = 0; i < DDRC_PERF_NUM_GEN_COUNTERS; i++) {
> +		if (pmu->events[i] == NULL) {
> +			pmu->events[i] = event;
> +			return i;
> +		}
> +	}
> +
> +	return -ENOENT;
> +}
> +
> +static void cn10k_ddr_perf_free_counter(struct cn10k_ddr_pmu *pmu, int counter)
> +{
> +	pmu->events[counter] = NULL;
> +}
> +
> +static int cn10k_ddr_perf_event_init(struct perf_event *event)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	if (event->attr.type != event->pmu->type)
> +		return -ENOENT;
> +
> +	if (is_sampling_event(event)) {
> +		dev_info(pmu->dev, "Sampling not supported!\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	if (event->cpu < 0) {
> +		dev_warn(pmu->dev, "Can't provide per-task data!\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	/*  We must NOT create groups containing mixed PMUs */
> +	if (event->group_leader->pmu != event->pmu &&
> +			!is_software_event(event->group_leader))

pay attention to indentation

> +		return -EINVAL;
> +
> +	/* Set ownership of event to one CPU, same event can not be observed
> +	 * on multiple cpus at same time.
> +	 */
> +	event->cpu = pmu->cpu;
> +	hwc->idx = -1;
> +	return 0;
> +}
> +
> +static void cn10k_ddr_perf_counter_enable(struct cn10k_ddr_pmu *pmu,
> +					  int counter, bool enable)
> +{
> +	uint32_t reg;
> +	uint64_t val;
> +
> +	if (counter > DDRC_PERF_NUM_COUNTERS) {

is this paranoia?

> +		pr_err("Error: unsupported counter %d\n", counter);
> +		return;
> +	}
> +
> +	if (counter < DDRC_PERF_NUM_GEN_COUNTERS) {
> +		reg = DDRC_PERF_CFG(counter);
> +		val = readq_relaxed(pmu->base + reg);
> +
> +		if (enable)
> +			val |= EVENT_ENABLE;
> +		else
> +			val &= ~EVENT_ENABLE;
> +
> +		writeq_relaxed(val, pmu->base + reg);
> +	} else {
> +		val = readq_relaxed(pmu->base + DDRC_PERF_CNT_FREERUN_EN);
> +		if (enable) {
> +			if (counter == DDRC_PERF_READ_COUNTER_IDX)
> +				val |= DDRC_PERF_FREERUN_READ_EN;
> +			else
> +				val |= DDRC_PERF_FREERUN_WRITE_EN;
> +		} else {
> +			if (counter == DDRC_PERF_READ_COUNTER_IDX)
> +				val &= ~DDRC_PERF_FREERUN_READ_EN;
> +			else
> +				val &= ~DDRC_PERF_FREERUN_WRITE_EN;
> +		}
> +		writeq_relaxed(val, pmu->base + DDRC_PERF_CNT_FREERUN_EN);
> +	}
> +}
> +
> +static uint64_t cn10k_ddr_perf_read_counter(struct cn10k_ddr_pmu *pmu,
> +					    int counter)
> +{
> +	uint64_t val;
> +
> +	if (counter == DDRC_PERF_READ_COUNTER_IDX)
> +		return readq_relaxed(pmu->base + DDRC_PERF_CNT_VALUE_RD_OP);
> +
> +	if (counter == DDRC_PERF_WRITE_COUNTER_IDX)
> +		return readq_relaxed(pmu->base + DDRC_PERF_CNT_VALUE_WR_OP);
> +
> +	val = readq_relaxed(pmu->base + DDRC_PERF_CNT_VALUE(counter));
> +	return val;
> +}
> +
> +static void cn10k_ddr_perf_event_update(struct perf_event *event)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	uint64_t prev_count, new_count, mask;
> +
> +	do {
> +		prev_count = local64_read(&hwc->prev_count);
> +		new_count = cn10k_ddr_perf_read_counter(pmu, hwc->idx);
> +	} while (local64_xchg(&hwc->prev_count, new_count) != prev_count);
> +
> +	mask = DDRC_PERF_CNT_MAX_VALUE;
> +
> +	local64_add((new_count - prev_count) & mask, &event->count);
> +}
> +
> +static void cn10k_ddr_perf_event_start(struct perf_event *event, int flags)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	int counter = hwc->idx;
> +
> +	local64_set(&hwc->prev_count, 0);
> +
> +	cn10k_ddr_perf_counter_enable(pmu, counter, true);
> +
> +	hwc->state = 0;
> +}
> +
> +static int cn10k_ddr_perf_event_add(struct perf_event *event, int flags)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	uint8_t config = event->attr.config;
> +	uint32_t reg_offset;
> +	uint64_t val;
> +	int counter;
> +
> +	counter = cn10k_ddr_perf_alloc_counter(pmu, event);
> +	if (counter < 0) {
> +		dev_dbg(pmu->dev, "There are not enough counters\n");

hmmm .. I'd be inclined to say that there are not enough available. And 
is dev_dbg() really any use?

> +		return -EOPNOTSUPP;

is that the best error code?

> +	}
> +
> +	pmu->active_events++;
> +	hwc->idx = counter;
> +
> +	if (counter < DDRC_PERF_NUM_GEN_COUNTERS) {
> +		/* Generic counters, configure event id */
> +		reg_offset = DDRC_PERF_CFG(counter);
> +		val = ddr_perf_get_event_bitmap(config);
> +		writeq_relaxed(val, pmu->base + reg_offset);
> +	} else {
> +		/* fixed event counter, clear counter value */
> +		if (counter == DDRC_PERF_READ_COUNTER_IDX)
> +			val = DDRC_FREERUN_READ_CNT_CLR;
> +		else
> +			val = DDRC_FREERUN_WRITE_CNT_CLR;
> +
> +		writeq_relaxed(val, pmu->base + DDRC_PERF_CNT_FREERUN_CTRL);
> +	}
> +
> +	hwc->state |= PERF_HES_STOPPED;
> +
> +	if (flags & PERF_EF_START)
> +		cn10k_ddr_perf_event_start(event, flags);
> +
> +	return 0;
> +}
> +
> +static void cn10k_ddr_perf_event_stop(struct perf_event *event, int flags)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	int counter = hwc->idx;
> +
> +	cn10k_ddr_perf_counter_enable(pmu, counter, false);
> +
> +	if (flags & PERF_EF_UPDATE)
> +		cn10k_ddr_perf_event_update(event);
> +
> +	hwc->state |= PERF_HES_STOPPED;
> +}
> +
> +static void cn10k_ddr_perf_event_del(struct perf_event *event, int flags)
> +{
> +	struct cn10k_ddr_pmu *pmu = to_cn10k_ddr_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	int counter = hwc->idx;
> +
> +	cn10k_ddr_perf_event_stop(event, PERF_EF_UPDATE);
> +
> +	cn10k_ddr_perf_free_counter(pmu, counter);
> +	pmu->active_events--;
> +	hwc->idx = -1;
> +}
> +
> +static void cn10k_ddr_perf_pmu_enable(struct pmu *pmu)
> +{
> +	struct cn10k_ddr_pmu *ddr_pmu = to_cn10k_ddr_pmu(pmu);
> +
> +	writeq_relaxed(START_OP_CTRL_VAL_START, ddr_pmu->base +
> +		       DDRC_PERF_CNT_START_OP_CTRL);
> +}
> +
> +static void cn10k_ddr_perf_pmu_disable(struct pmu *pmu)
> +{
> +	struct cn10k_ddr_pmu *ddr_pmu = to_cn10k_ddr_pmu(pmu);
> +
> +	writeq_relaxed(END_OP_CTRL_VAL_END, ddr_pmu->base +
> +		       DDRC_PERF_CNT_END_OP_CTRL);
> +}
> +
> +static int cn10k_ddr_perf_probe(struct platform_device *pdev)
> +{
> +	struct cn10k_ddr_pmu *ddr_pmu;
> +	struct resource *res;
> +	void __iomem *base;
> +	static int index;
> +	char *name;
> +	int ret;
> +
> +	ddr_pmu = devm_kzalloc(&pdev->dev, sizeof(*ddr_pmu), GFP_KERNEL);
> +	if (!ddr_pmu)
> +		return -ENOMEM;
> +
> +	ddr_pmu->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, ddr_pmu);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);

can you use devm_platform_get_and_ioremap_resource()? I think that there 
is some helper that does both these steps

> +
> +	ddr_pmu->base = base;
> +
> +	/* Setup the PMU counter to work in mannual mode */

manual

> +	writeq_relaxed(OP_MODE_CTRL_VAL_MANNUAL, ddr_pmu->base +
> +		       DDRC_PERF_CNT_OP_MODE_CTRL);
> +
> +	ddr_pmu->pmu = (struct pmu) {
> +		.module	      = THIS_MODULE,
> +		.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
> +		.task_ctx_nr = perf_invalid_context,
> +		.attr_groups = cn10k_attr_groups,
> +		.event_init  = cn10k_ddr_perf_event_init,
> +		.add	     = cn10k_ddr_perf_event_add,
> +		.del	     = cn10k_ddr_perf_event_del,
> +		.start	     = cn10k_ddr_perf_event_start,
> +		.stop	     = cn10k_ddr_perf_event_stop,
> +		.read	     = cn10k_ddr_perf_event_update,
> +		.pmu_enable  = cn10k_ddr_perf_pmu_enable,
> +		.pmu_disable = cn10k_ddr_perf_pmu_disable,
> +	};
> +
> +	/* Choose this cpu to collect perf data */
> +	ddr_pmu->cpu = raw_smp_processor_id();
> +
> +	name = devm_kasprintf(ddr_pmu->dev, GFP_KERNEL, "mrvl_ddr_pmu@...x",

mostly _%llx would be used elsewhere, and I am not sure how perf tool 
likes @ at all

> +			      res->start);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	ret = perf_pmu_register(&ddr_pmu->pmu, name, -1);
> +	if (ret)
> +		return ret;
> +
> +	ddr_pmu->id = index++;

where is this used?

> +	pr_info("CN10K DDR PMU Driver for ddrc@...x - id-%d\n",
> +		res->start, ddr_pmu->id);
> +	return 0;
> +}
> +
> +static int cn10k_ddr_perf_remove(struct platform_device *pdev)
> +{
> +	struct cn10k_ddr_pmu *ddr_pmu = platform_get_drvdata(pdev);
> +
> +	perf_pmu_unregister(&ddr_pmu->pmu);
> +	return 0;
> +}
> +
> +static const struct of_device_id cn10k_ddr_pmu_of_match[] = {
> +	{ .compatible = "marvell,cn10k-ddr-pmu", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, cn10k_ddr_pmu_of_match);
> +
> +static struct platform_driver cn10k_ddr_pmu_driver = {
> +	.driver	= {
> +		.name   = "cn10k-ddr-pmu",
> +		.of_match_table = cn10k_ddr_pmu_of_match,
> +		.suppress_bind_attrs = true,
> +	},
> +	.probe		= cn10k_ddr_perf_probe,
> +	.remove		= cn10k_ddr_perf_remove,
> +};
> +
> +static int __init cn10k_ddr_pmu_init(void)
> +{
> +	return platform_driver_register(&cn10k_ddr_pmu_driver);
> +}
> +
> +static void __exit cn10k_ddr_pmu_exit(void)
> +{
> +	platform_driver_unregister(&cn10k_ddr_pmu_driver);
> +}
> +
> +module_init(cn10k_ddr_pmu_init);
> +module_exit(cn10k_ddr_pmu_exit);
> +
> +MODULE_AUTHOR("Bharat Bhushan <bbhushan2@...vell.com>");
> +MODULE_LICENSE("GPL v2");
> 

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