Message-ID: <CO6PR18MB4465D5490C1F6141DB454064E3C09@CO6PR18MB4465.namprd18.prod.outlook.com>
Date:   Thu, 19 Aug 2021 11:52:00 +0000
From:   Bharat Bhushan <bbhushan2@...vell.com>
To:     John Garry <john.garry@...wei.com>,
        "will@...nel.org" <will@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [EXT] Re: [PATCH v2 2/4] perf/marvell: CN10k DDR performance
 monitor support

Please see inline

> -----Original Message-----
> From: John Garry <john.garry@...wei.com>
> Sent: Wednesday, August 18, 2021 7:19 PM
> 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: [EXT] Re: [PATCH v2 2/4] perf/marvell: CN10k DDR performance monitor
> support
> 
> External Email
> 
> ----------------------------------------------------------------------
> 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

Ok,

> 
> >
> > 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

Just keeping same as other drivers

> 
> > +	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...

Yes, do you see any unused?

> 
> > +
> > +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.

Yes, Thanks for pointing.

> 
> > +}
> > +
> > +#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

As of now we do not have ddr pmu versioning.

> 
> > +	CN10K_DDR_PMU_EVENT_ATTR(ddr_ddr_writes, EVENT_DDR_WRITES),
> > +	NULL,
> 
> no need for ',' when the array is not going to be expanded

Oh yes,

> 
> > +};
> > +
> > +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?

I am not aware of any guidance or rule, both are being used.
I end up using uint64_t and u64 both, will use one only with next version. 

> 
> > +{
> > +	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)?

Ack, currently it just through error but does not error out.

> 
> > +		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

Accepted, not sure how this got in.

> 
> > +		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?

We can not program if counter by any means is out or range.

> 
> > +		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?

Maybe we can remove the error print now, and return 

> 
> > +		return -EOPNOTSUPP;
> 
> is that the best error code?

Looks like we should let it try again later  "-EAGAIN"

> 
> > +	}
> > +
> > +	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

Yes, devm_platform_get_and_ioremap_resource() does both.
 

> 
> > +
> > +	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

Will be consistent with other,

> 
> > +			      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?

Just below to keep count of number of instance.

Thanks for review, will do required changes in next version.

Thanks
-Bharat
> 
> > +	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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