Message-ID: <20170609132320.GD10665@leverpostej>
Date:   Fri, 9 Jun 2017 14:23:20 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Shaokun Zhang <zhangshaokun@...ilicon.com>
Cc:     will.deacon@....com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, anurup.m@...wei.com,
        tanxiaojun@...wei.com, xuwei5@...ilicon.com,
        sanil.kumar@...ilicon.com, john.garry@...wei.com,
        gabriele.paoloni@...wei.com, shiju.jose@...wei.com,
        huangdaode@...ilicon.com, linuxarm@...wei.com,
        dikshit.n@...wei.com, shyju.pv@...wei.com, anurupvasu@...il.com
Subject: Re: [PATCH v8 7/9] drivers: perf: hisi: Add support for Hisilicon
 SoC event counters

Hi,

On Mon, May 22, 2017 at 08:48:35PM +0800, Shaokun Zhang wrote:
> +/*
> + * ARMv8 HiSilicon Hardware counter Index.
> + */
> +enum hisi_l3c_pmu_counters {
> +	HISI_IDX_L3C_COUNTER0		= 0x0,
> +	HISI_IDX_L3C_COUNTER_MAX	= 0x8,

Just to check, there are 8 counters, numbered 0-7, right?

So HISI_IDX_L3C_COUNTER_MAX is a misleading name. It would be better to
have:

#define HISI_L3C_NR_COUNTERS	8

... and not bother with HISI_IDX_L3C_COUNTER0 at all.

[...]

> +#define L3C_EVTYPE_REG_OFF 0x140
> +#define L3C_EVCTRL_REG_OFF 0x04
> +#define L3C_CNT0_REG_OFF 0x170

Please get rid of the _REG_OFF suffixes, and use tabs to indent the
numbers so that they're kept aligned.

I see that L3C_EVTYPE_REG_OFF represents L3C_EVENT_TYPE0. Please use
names for the specific registers.

#define L3C_EVENT_TYPE0		0x140
#define L3C_EVENT_TYPE1		0x144

[...]

> +#define L3C_EVENT_EN 0x1000000

It would be good to prefix this with the register name, to make it clear
where it applies.

> +/*
> + * Default timer frequency to poll and avoid counter overflow.
> + * CPU speed = 2.4Ghz, Therefore Access time = 0.4ns
> + * L1 cache - 2 way set associative
> + * L2  - 16 way set associative
> + * L3  - 16 way set associative. L3 cache has 4 banks.
> + *
> + * Overflow time = 2^31 * (access time L1 + access time L2 + access time L3)
> + * = 2^31 * ((2 * 0.4ns) + (16 * 0.4ns) + (4 * 16 * 0.4ns)) = 70 seconds
> + *
> + * L3 cache is also used by devices like PCIe, SAS etc. at
> + * the same time. So the overflow time could be even smaller.
> + * So on a safe side we use a timer interval of 10sec
> + */
> +#define L3C_HRTIMER_INTERVAL (10LL * MSEC_PER_SEC)
> +
> +#define GET_MODULE_ID(hwmod_data) hwmod_data->module_id
> +#define GET_BANK_SEL(hwmod_data) hwmod_data->bank_select

Please get rid of these. They don't save anything over directly
accessing these fields, while making it look as if they do.

> +#define L3C_EVTYPE_REG(idx)	(L3C_EVTYPE_REG_OFF + (idx <= 3 ? 0 : 4))
> +
> +struct hisi_l3c_data {
> +	struct hisi_djtag_client *client;
> +	u32 module_id;
> +	u32 bank_select;

... and if typing is a pain, then we can shorten these to mod_id and
bank_sel.

> +	u32 bank_id;
> +};
> +
> +struct hisi_l3c_pmu_hw_diff {
> +	u32 (*get_bank_id)(u32 module_id, u32 bank_select);
> +};

This structure is confusingly named. What is the "diff" referring to?

> +
> +/* hip05/06 chips L3C instance or bank identifier */
> +static u32 l3c_bankid_map_v1[MAX_BANKS] = {
> +	0x02, 0x04, 0x01, 0x08,
> +};
> +
> +/* hip07 chip L3C instance or bank identifier */
> +static u32 l3c_bankid_map_v2[MAX_BANKS] = {
> +	0x01, 0x02, 0x03, 0x04,
> +};

Back in v6, I asked for these to be described in the DT [1], and Anurup
said they would be [2].

Please describe this mapping in the DT.

[1] https://lkml.kernel.org/r/20170321165252.GA29116@leverpostej
[2] https://lkml.kernel.org/r/58D8B25E.90308@gmail.com

[...]

> +static void hisi_l3c_pmu_set_evtype(struct hisi_pmu *l3c_pmu, int idx, u32 val)
> +{
> +	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
> +	struct hisi_djtag_client *client = l3c_data->client;
> +	u32 module_id = GET_MODULE_ID(l3c_data);
> +	u32 bank_sel = GET_BANK_SEL(l3c_data);
> +	u32 reg_off, event_value, value = 0;
> +
> +	event_value = (val - HISI_HWEVENT_L3C_READ_ALLOCATE);
> +
> +	/*
> +	 * Select the appropriate Event select register(L3C_EVENT_TYPEx).
> +	 * There are 2 Event Select registers for the 8 hardware counters.
> +	 * For the first 4 hardware counters, the L3C_EVTYPE_REG_OFF is chosen.
> +	 * For the next 4 hardware counters, the second register is chosen.
> +	 */
> +	reg_off = L3C_EVTYPE_REG(idx);
> +
> +	/*
> +	 * Write the event code in L3C_EVENT_TYPEx Register
> +	 * Each byte in the 32 bit event select register is used to configure
> +	 * the event code. Each byte correspond to a counter register to use.
> +	 * Use (idx % 4) to select the byte to update in event select register
> +	 * with the event code.
> +	 */
> +	val = event_value << (8 * (idx % 4));
> +
> +	hisi_djtag_readreg(module_id, bank_sel, reg_off, client, &value);
> +	value &= ~(0xff << (8 * (idx % 4)));
> +	value |= val;
> +	hisi_djtag_writereg(module_id, bank_sel, reg_off, value, client);
> +}
> +
> +static void hisi_l3c_pmu_clear_evtype(struct hisi_pmu *l3c_pmu, int idx)
> +{
> +	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
> +	struct hisi_djtag_client *client = l3c_data->client;
> +	u32 module_id = GET_MODULE_ID(l3c_data);
> +	u32 bank_sel = GET_BANK_SEL(l3c_data);
> +	u32 reg_off, value;
> +
> +	if (!hisi_l3c_pmu_counter_valid(idx)) {
> +		dev_err(l3c_pmu->dev, "Unsupported event index:%d!\n", idx);
> +		return;
> +	}
> +
> +	/*
> +	 * Clear Counting in L3C event config register.
> +	 * Select the appropriate Event select register(L3C_EVENT_TYPEx).
> +	 * There are 2 Event Select registers for the 8 hardware counters.
> +	 * For the first 4 hardware counters, the L3C_EVTYPE_REG_OFF is chosen.
> +	 * For the next 4 hardware counters, the second register is chosen.
> +	 */
> +	reg_off = L3C_EVTYPE_REG(idx);
> +
> +	/*
> +	 * Clear the event in L3C_EVENT_TYPEx Register
> +	 * Each byte in the 32 bit event select register is used to configure
> +	 * the event code. Each byte correspond to a counter register to use.
> +	 * Use (idx % 4) to select the byte to clear in event select register
> +	 * with the vale 0xff.
> +	 */
> +	hisi_djtag_readreg(module_id, bank_sel, reg_off, client, &value);
> +	value &= ~(0xff << (8 * (idx % 4)));
> +	value |= (0xff << (8 * (idx % 4)));
> +	hisi_djtag_writereg(module_id, bank_sel, reg_off, value, client);
> +}

These set/clear functions share most of the same logic and comments.

Let's factor that out into a common helper:

static void hisi_l3c_pmu_set_evtype_idx(struct hisi_pmu *l3c_pmu, int idx, u8 type)
{
	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
	struct hisi_djtag_client *client = l3c_data->client;
	u32 module_id = GET_MODULE_ID(l3c_data);
	u32 bank_sel = GET_BANK_SEL(l3c_data);
	u32 reg, reg_idx, shift, val;

	if (!hisi_l3c_pmu_counter_valid(idx)) {
		dev_err(l3c_pmu->dev, "accessing invalid event idx %d\n", idx);
		return;
	}

	/*
	 * Each event has an 8-bit field in the 32-bit L3C_EVENT_TYPEx
	 * registers. L3C_EVENT_TYPE0 handles events [0,3] and
	 * L3C_EVENT_TYPE1 handles events [4,7]. L3C_EVENT_TYPE0
	 * immediately precedes L3C_EVENT_TYPE1.
	 */
	reg = L3C_EVTYPE_REG_OFF + (idx / 4);
	reg_idx = idx % 4;
	shift = 8 * reg_idx;

	hisi_djtag_readreg(module_id, bank_sel, reg_off, client, &val);
	val &= ~(0xff << shift);
	val |= ((u32)type << shift);
	hisi_djtag_writereg(module_id, bank_sel, reg_off, val, client);
}

... and simplify the clear/set functions:

#define L3C_EVTYPE_NONE		0xff

static void hisi_l3c_pmu_set_evtype(struct hisi_pmu *l3c_pmu, int idx, u32 type)
{
	hisi_l3c_pmu_set_evtype_idx(l3c_pmu, idx, type);
}

static void hisi_l3c_pmu_clear_evtype(struct hisi_pmu *l3c_pmu, int idx)
{
	hisi_l3c_pmu_set_evtype_idx(l3c_pmu, idx, L3C_EVTYPE_NONE);
}

... also, can we have accessors that takes the l3c_data rather than
having to extract that manually all over the place? e.g.

u32 l3c_reg_read(struct hisi_l3c_data *l3c, u32 reg)
{
	u32 val;
	hisi_djtag_readreg(l3c->module_id, l3c->bank_select, client, &val);
	return val;
}

void l3c_reg_write(struct hisi_l3c_data *l3c, u32 reg, u32 val)
{
	hisi_djtag_writereg(l3c->module_id, l3c->bank_select, reg, val, l3c->client);
}

... this would significantly simplify most of the code.

> +static void hisi_l3c_pmu_write_counter(struct hisi_pmu *l3c_pmu,
> +				       struct hw_perf_event *hwc, u32 value)
> +{
> +	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
> +	struct hisi_djtag_client *client = l3c_data->client;
> +	u32 module_id = GET_MODULE_ID(l3c_data);
> +	u32 bank_sel = GET_BANK_SEL(l3c_data);
> +	u32 reg_off;
> +	int idx = GET_CNTR_IDX(hwc);

Please use hwc->idx directly, and get rid of GET_CNTR_IDX().

> +
> +	reg_off = get_counter_reg_off(idx);
> +	hisi_djtag_writereg(module_id, bank_sel, reg_off, value, client);
> +}
> +
> +static void hisi_l3c_pmu_start_counters(struct hisi_pmu *l3c_pmu)
> +{
> +	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
> +	struct hisi_djtag_client *client = l3c_data->client;
> +	unsigned long *used_mask = l3c_pmu->pmu_events.used_mask;
> +	u32 module_id = GET_MODULE_ID(l3c_data);
> +	u32 bank_sel = GET_BANK_SEL(l3c_data);
> +	u32 num_counters = l3c_pmu->num_counters;
> +	u32 value;
> +	int enabled = bitmap_weight(used_mask, num_counters);
> +
> +	if (!enabled)
> +		return;
> +
> +	/*
> +	 * Set the event_bus_en bit in L3C AUCNTRL to start counting
> +	 * for the L3C bank
> +	 */
> +	hisi_djtag_readreg(module_id, bank_sel, L3C_EVCTRL_REG_OFF,
> +			   client, &value);

Is the register named L3C AUCNTRL or L3C_EVCTRL_REG_OFF?

Please make these consistent, and elsewhere, too.

> +	value |= L3C_EVENT_EN;
> +	hisi_djtag_writereg(module_id, bank_sel, L3C_EVCTRL_REG_OFF,
> +			    value, client);
> +}
> +
> +static void hisi_l3c_pmu_stop_counters(struct hisi_pmu *l3c_pmu)
> +{
> +	struct hisi_l3c_data *l3c_data = l3c_pmu->hwmod_data;
> +	struct hisi_djtag_client *client = l3c_data->client;
> +	u32 module_id = GET_MODULE_ID(l3c_data);
> +	u32 bank_sel = GET_BANK_SEL(l3c_data);
> +	u32 value;
> +

Here you could also skip if there were no events.

[...]

> +static struct attribute *hisi_l3c_pmu_events_attr[] = {
> +	HISI_PMU_EVENT_ATTR_STR(read_allocate, "event=0x0"),
> +	HISI_PMU_EVENT_ATTR_STR(write_allocate, "event=0x01"),
> +	HISI_PMU_EVENT_ATTR_STR(read_noallocate, "event=0x02"),
> +	HISI_PMU_EVENT_ATTR_STR(write_noallocate, "event=0x03"),
> +	HISI_PMU_EVENT_ATTR_STR(read_hit, "event=0x04"),
> +	HISI_PMU_EVENT_ATTR_STR(write_hit, "event=0x05"),
> +	NULL,
> +};

Duplicating these values is unfortunate. Can we use the mnemonics
defined in enum hisi_l3c_pmu_event_types?

[...]

> +	/* Get the L3C bank index to set the pmu name */
> +	l3c_data->bank_id = l3c_hw->get_bank_id(l3c_data->module_id,
> +						l3c_data->bank_select);

With this in the DT, hisi_l3c_pmu_get_module_instance_id() should
probably handle this, and should be renamed to something like
hisi_l3c_pmu_get_data().

> +	if (l3c_data->bank_id == MAX_BANKS) {
> +		dev_err(dev, "Invalid bank-select!\n");
> +		return -EINVAL;
> +	}
> +
> +	hisi_l3c_pmu_init_data(l3c_pmu, client);
> +
> +	return 0;
> +}

[...]

> +/*
> + * PMU format attributes
> + */
> +ssize_t hisi_format_sysfs_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);
> +}
> +
> +/*
> + * PMU event attributes
> + */
> +ssize_t hisi_event_sysfs_show(struct device *dev,
> +			      struct device_attribute *attr, char *page)
> +{
> +	struct perf_pmu_events_attr *pmu_attr =
> +		container_of(attr, struct perf_pmu_events_attr, attr);
> +
> +	return sprintf(page, "%s", pmu_attr->event_str);
> +}

As we're just printing a string, surely you could use the same attribute
type for both, and handle the newline consistently?

[...]

> +static void hisi_uncore_pmu_disable_event(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct hisi_pmu *hisi_pmu = to_hisi_pmu(event->pmu);
> +
> +	/* Disable the hardware event counting */
> +	if (hisi_pmu->ops->disable_counter)
> +		hisi_pmu->ops->disable_counter(hisi_pmu, GET_CNTR_IDX(hwc));

There's no disable_counter implementation in this patch or any
subsequent patch. So I think we should remove it.

Likewise for enable_counter.

> +
> +	/*
> +	 * Clear event in Event select registers.
> +	 */
> +	hisi_pmu->ops->clear_evtype(hisi_pmu, GET_CNTR_IDX(hwc));
> +}

[...]

> +void hisi_uncore_pmu_start(struct perf_event *event, int flags)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct hisi_pmu *hisi_pmu = to_hisi_pmu(event->pmu);
> +
> +	if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
> +		return;
> +
> +	WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
> +	hwc->state = 0;
> +	hisi_pmu->ops->set_event_period(event);
> +
> +	if (flags & PERF_EF_RELOAD) {
> +		u64 prev_raw_count =  local64_read(&hwc->prev_count);
> +
> +		hisi_pmu->ops->write_counter(hisi_pmu, hwc,
> +					     (u32) prev_raw_count);
> +	}
> +
> +	/* Start hrtimer when the first event is started in this PMU */
> +	if (hisi_pmu->ops->start_hrtimer) {
> +		hisi_pmu->num_active++;
> +		list_add_tail(&event->active_entry, &hisi_pmu->active_list);
> +
> +		if (hisi_pmu->num_active == 1)
> +			hisi_pmu->ops->start_hrtimer(hisi_pmu);
> +	}

We should probably keep track of num_active regardless. Then we can use
it to avoid work in the pmu_{enable,disable} methods.

> +
> +	hisi_uncore_pmu_enable_event(event);
> +	perf_event_update_userpage(event);
> +}

[...]

> +struct hisi_pmu *hisi_pmu_alloc(struct device *dev, u32 num_cntrs)
> +{
> +	struct hisi_pmu *hisi_pmu;
> +	struct hisi_pmu_hwevents *pmu_events;
> +
> +	hisi_pmu = devm_kzalloc(dev, sizeof(*hisi_pmu), GFP_KERNEL);
> +	if (!hisi_pmu)
> +		return ERR_PTR(-ENOMEM);
> +
> +	pmu_events = &hisi_pmu->pmu_events;
> +	pmu_events->hw_events = devm_kcalloc(dev,
> +					     num_cntrs,
> +					     sizeof(*pmu_events->hw_events),
> +					     GFP_KERNEL);
> +	if (!pmu_events->hw_events)
> +		return ERR_PTR(-ENOMEM);
> +
> +	pmu_events->used_mask = devm_kcalloc(dev,
> +					     BITS_TO_LONGS(num_cntrs),
> +					     sizeof(*pmu_events->used_mask),
> +					     GFP_KERNEL);
> +	if (!pmu_events->used_mask)
> +		return ERR_PTR(-ENOMEM);

Why is this a dynamic allocation ratehr than part of hisi_pmu_hwevents?

We already know an upper bound for num_cntrs that we can use for
allocation.

Thanks,
Mark.

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