Re: [PATCH v4] driver/perf: Add PMU driver for the ARM DMC-620 memory controller
From: Robin Murphy
Date: Thu Oct 22 2020 - 13:34:34 EST
On 2020-10-21 00:10, Tuan Phan wrote:
DMC-620 PMU supports total 10 counters which each is
independently programmable to different events and can
be started and stopped individually.
Currently, it only supports ACPI. Other platforms feel free to test and add
support for device tree.
Usage example:
#perf stat -e arm_dmc620_10008c000/clk_cycle_count/ -C 0
Get perf event for clk_cycle_count counter.
#perf stat -e arm_dmc620_10008c000/clkdiv2_allocate,mask=0x1f,match=0x2f,
incr=2,invert=1/ -C 0
The above example shows how to specify mask, match, incr,
invert parameters for clkdiv2_allocate event.
Signed-off-by: Tuan Phan <tuanphan@xxxxxxxxxxxxxxxxxxxxxx>
---
Changes in v4:
- Addressed Robin's comments.
Changes in v3:
- Removed "_OFFSET" suffix.
- Renamed "affinity" to "irq".
- Have a better definition of group register.
Changes in v2:
- Removed IRQF_SHARED flag and added support for multiple
PMUs sharing the same interrupt.
- Fixed an interrupt handler race condition.
The ACPI binding spec for PMU DMC620 can be downloaded at:
https://developer.arm.com/documentation/den0093/c/
drivers/perf/Kconfig | 7 +
drivers/perf/Makefile | 1 +
drivers/perf/arm_dmc620_pmu.c | 746 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 754 insertions(+)
create mode 100644 drivers/perf/arm_dmc620_pmu.c
diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 130327ff..3075cf1 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -130,6 +130,13 @@ config ARM_SPE_PMU
Extension, which provides periodic sampling of operations in
the CPU pipeline and reports this via the perf AUX interface.
+config ARM_DMC620_PMU
+ tristate "Enable PMU support for the ARM DMC-620 memory controller"
+ depends on (ARM64 && ACPI) || COMPILE_TEST
+ help
+ Support for PMU events monitoring on the ARM DMC-620 memory
+ controller.
+
source "drivers/perf/hisilicon/Kconfig"
endmenu
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index 5365fd5..5260b11 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -13,3 +13,4 @@ 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
+obj-$(CONFIG_ARM_DMC620_PMU) += arm_dmc620_pmu.o
diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c
new file mode 100644
index 0000000..d72cd54
--- /dev/null
+++ b/drivers/perf/arm_dmc620_pmu.c
@@ -0,0 +1,746 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ARM DMC-620 memory controller PMU driver
+ *
+ * Copyright (C) 2020 Ampere Computing LLC.
+ */
+
+#define DMC620_PMUNAME "arm_dmc620"
+#define DMC620_DRVNAME DMC620_PMUNAME "_pmu"
+#define pr_fmt(fmt) DMC620_DRVNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cpuhotplug.h>
+#include <linux/cpumask.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/perf_event.h>
+#include <linux/perf/arm_pmu.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/rculist.h>
+#include <linux/refcount.h>
+
+#define DMC620_PA_SHIFT 12
+#define DMC620_CNT_INIT 0x80000000
+#define DMC620_CNT_MAX_PERIOD 0xffffffff
+#define DMC620_PMU_CLKDIV2_MAX_COUNTERS 8
+#define DMC620_PMU_CLK_MAX_COUNTERS 2
+#define DMC620_PMU_MAX_COUNTERS \
+ (DMC620_PMU_CLKDIV2_MAX_COUNTERS + DMC620_PMU_CLK_MAX_COUNTERS)
+
+/*
+ * The PMU registers start at 0xA00 in the DMC-620 memory map, and these
+ * offsets are relative to that base.
+ *
+ * Each counter has a group of control/value registers, and the
+ * DMC620_PMU_COUNTERn offsets are within a counter group.
+ *
+ * The counter registers groups start at 0xA10.
+ */
+#define DMC620_PMU_OVERFLOW_STATUS_CLKDIV2 0x8
+#define DMC620_PMU_OVERFLOW_STATUS_CLKDIV2_MASK \
+ (DMC620_PMU_CLKDIV2_MAX_COUNTERS - 1)
+#define DMC620_PMU_OVERFLOW_STATUS_CLK 0xC
+#define DMC620_PMU_OVERFLOW_STATUS_CLK_MASK \
+ (DMC620_PMU_CLK_MAX_COUNTERS - 1)
+#define DMC620_PMU_COUNTERS_BASE 0x10
+#define DMC620_PMU_COUNTERn_MASK_31_00 0x0
+#define DMC620_PMU_COUNTERn_MASK_63_32 0x4
+#define DMC620_PMU_COUNTERn_MATCH_31_00 0x8
+#define DMC620_PMU_COUNTERn_MATCH_63_32 0xC
+#define DMC620_PMU_COUNTERn_CONTROL 0x10
+#define DMC620_PMU_COUNTERn_CONTROL_ENABLE BIT(0)
+#define DMC620_PMU_COUNTERn_CONTROL_INVERT BIT(1)
+#define DMC620_PMU_COUNTERn_CONTROL_EVENT_MUX GENMASK(6, 2)
+#define DMC620_PMU_COUNTERn_CONTROL_INCR_MUX GENMASK(8, 7)
+#define DMC620_PMU_COUNTERn_VALUE 0x20
+/* Offset of the registers for a given counter, relative to 0xA00 */
+#define DMC620_PMU_COUNTERn_OFFSET(n) \
+ (DMC620_PMU_COUNTERS_BASE + 0x28 * (n))
+
+static LIST_HEAD(dmc620_pmu_irqs);
+static DEFINE_MUTEX(dmc620_pmu_irqs_lock);
+
+struct dmc620_pmu_irq {
+ struct hlist_node node;
+ struct list_head pmus_node;
+ struct list_head irqs_node;
+ refcount_t refcount;
+ unsigned int irq_num;
+ unsigned int cpu;
+};
+
+struct dmc620_pmu {
+ struct pmu pmu;
+ struct platform_device *pdev;
+
+ void __iomem *base;
+ struct dmc620_pmu_irq *irq;
+ struct list_head pmus_node;
+
+ /*
+ * We put all clkdiv2 and clk counters to a same array.
+ * The first DMC620_PMU_CLKDIV2_MAX_COUNTERS bits belong to
+ * clkdiv2 counters, the last DMC620_PMU_CLK_MAX_COUNTERS
+ * belong to clk counters.
+ */
+ DECLARE_BITMAP(used_mask, DMC620_PMU_MAX_COUNTERS);
+ struct perf_event *events[DMC620_PMU_MAX_COUNTERS];
+};
+
+#define to_dmc620_pmu(p) (container_of(p, struct dmc620_pmu, pmu))
+
+static int cpuhp_state_num;
+
+struct dmc620_pmu_event_attr {
+ struct device_attribute attr;
+ u8 clkdiv2;
+ u8 eventid;
+};
+
+static ssize_t
+dmc620_pmu_event_show(struct device *dev,
+ struct device_attribute *attr, char *page)
+{
+ struct dmc620_pmu_event_attr *eattr;
+
+ eattr = container_of(attr, typeof(*eattr), attr);
+
+ return sprintf(page, "event=0x%x,clkdiv2=0x%x\n", eattr->eventid, eattr->clkdiv2);
+}
+
+#define DMC620_PMU_EVENT_ATTR(_name, _eventid, _clkdiv2) \
+ (&((struct dmc620_pmu_event_attr[]) {{ \
+ .attr = __ATTR(_name, 0444, dmc620_pmu_event_show, NULL), \
+ .clkdiv2 = _clkdiv2, \
+ .eventid = _eventid, \
+ }})[0].attr.attr)
+
+static struct attribute *dmc620_pmu_events_attrs[] = {
+ /* clkdiv2 events list */
+ DMC620_PMU_EVENT_ATTR(clkdiv2_cycle_count, 0x0, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_allocate, 0x1, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_queue_depth, 0x2, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_waiting_for_wr_data, 0x3, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_read_backlog, 0x4, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_waiting_for_mi, 0x5, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_hazard_resolution, 0x6, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_enqueue, 0x7, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_arbitrate, 0x8, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_lrank_turnaround_activate, 0x9, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_prank_turnaround_activate, 0xa, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_read_depth, 0xb, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_write_depth, 0xc, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_highigh_qos_depth, 0xd, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_high_qos_depth, 0xe, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_medium_qos_depth, 0xf, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_low_qos_depth, 0x10, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_activate, 0x11, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_rdwr, 0x12, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_refresh, 0x13, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_training_request, 0x14, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_t_mac_tracker, 0x15, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_bk_fsm_tracker, 0x16, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_bk_open_tracker, 0x17, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_ranks_in_pwr_down, 0x18, 1),
+ DMC620_PMU_EVENT_ATTR(clkdiv2_ranks_in_sref, 0x19, 1),
+
+ /* clk events list */
+ DMC620_PMU_EVENT_ATTR(clk_cycle_count, 0x0, 0),
+ DMC620_PMU_EVENT_ATTR(clk_request, 0x1, 0),
+ DMC620_PMU_EVENT_ATTR(clk_upload_stall, 0x2, 0),
+ NULL,
+};
+
+static struct attribute_group dmc620_pmu_events_attr_group = {
+ .name = "events",
+ .attrs = dmc620_pmu_events_attrs,
+};
+
+/* User ABI */
+#define ATTR_CFG_FLD_mask_CFG config
+#define ATTR_CFG_FLD_mask_LO 0
+#define ATTR_CFG_FLD_mask_HI 44
+#define ATTR_CFG_FLD_match_CFG config1
+#define ATTR_CFG_FLD_match_LO 0
+#define ATTR_CFG_FLD_match_HI 44
+#define ATTR_CFG_FLD_invert_CFG config2
+#define ATTR_CFG_FLD_invert_LO 0
+#define ATTR_CFG_FLD_invert_HI 0
+#define ATTR_CFG_FLD_incr_CFG config2
+#define ATTR_CFG_FLD_incr_LO 1
+#define ATTR_CFG_FLD_incr_HI 2
+#define ATTR_CFG_FLD_event_CFG config2
+#define ATTR_CFG_FLD_event_LO 3
+#define ATTR_CFG_FLD_event_HI 8
+#define ATTR_CFG_FLD_clkdiv2_CFG config2
+#define ATTR_CFG_FLD_clkdiv2_LO 9
+#define ATTR_CFG_FLD_clkdiv2_HI 9
+
+#define __GEN_PMU_FORMAT_ATTR(cfg, lo, hi) \
+ (lo) == (hi) ? #cfg ":" #lo "\n" : #cfg ":" #lo "-" #hi
+
+#define _GEN_PMU_FORMAT_ATTR(cfg, lo, hi) \
+ __GEN_PMU_FORMAT_ATTR(cfg, lo, hi)
+
+#define GEN_PMU_FORMAT_ATTR(name) \
+ PMU_FORMAT_ATTR(name, \
+ _GEN_PMU_FORMAT_ATTR(ATTR_CFG_FLD_##name##_CFG, \
+ ATTR_CFG_FLD_##name##_LO, \
+ ATTR_CFG_FLD_##name##_HI))
+
+#define _ATTR_CFG_GET_FLD(attr, cfg, lo, hi) \
+ ((((attr)->cfg) >> lo) & GENMASK(hi - lo, 0))
As per the buildbot report, GENMASK_ULL() would be appropriate when the
other side is a u64 (although either way this does look a lot like
reinventing FIELD_GET()...)
+#define ATTR_CFG_GET_FLD(attr, name) \
+ _ATTR_CFG_GET_FLD(attr, \
+ ATTR_CFG_FLD_##name##_CFG, \
+ ATTR_CFG_FLD_##name##_LO, \
+ ATTR_CFG_FLD_##name##_HI)
+
+GEN_PMU_FORMAT_ATTR(mask);
+GEN_PMU_FORMAT_ATTR(match);
+GEN_PMU_FORMAT_ATTR(invert);
+GEN_PMU_FORMAT_ATTR(incr);
+GEN_PMU_FORMAT_ATTR(event);
+GEN_PMU_FORMAT_ATTR(clkdiv2);
+
+static struct attribute *dmc620_pmu_formats_attrs[] = {
+ &format_attr_mask.attr,
+ &format_attr_match.attr,
+ &format_attr_invert.attr,
+ &format_attr_incr.attr,
+ &format_attr_event.attr,
+ &format_attr_clkdiv2.attr,
+ NULL,
+};
+
+static struct attribute_group dmc620_pmu_format_attr_group = {
+ .name = "format",
+ .attrs = dmc620_pmu_formats_attrs,
+};
+
+static const struct attribute_group *dmc620_pmu_attr_groups[] = {
+ &dmc620_pmu_events_attr_group,
+ &dmc620_pmu_format_attr_group,
+ NULL,
+};
+
+static inline
+u32 dmc620_pmu_creg_read(struct dmc620_pmu *dmc620_pmu,
+ unsigned int idx, unsigned int reg)
+{
+ return readl(dmc620_pmu->base + DMC620_PMU_COUNTERn_OFFSET(idx) + reg);
+}
+
+static inline
+void dmc620_pmu_creg_write(struct dmc620_pmu *dmc620_pmu,
+ unsigned int idx, unsigned int reg, u32 val)
+{
+ writel(val, dmc620_pmu->base + DMC620_PMU_COUNTERn_OFFSET(idx) + reg);
+}
+
+static
+unsigned int dmc620_event_to_counter_control(struct perf_event *event)
+{
+ struct perf_event_attr *attr = &event->attr;
+ unsigned int reg = 0;
+
+ reg |= FIELD_GET(DMC620_PMU_COUNTERn_CONTROL_INVERT,
FIELD_PREP(), surely? (all 3 times)
+ ATTR_CFG_GET_FLD(attr, invert));
+ reg |= FIELD_GET(DMC620_PMU_COUNTERn_CONTROL_INCR_MUX,
+ ATTR_CFG_GET_FLD(attr, incr));
+ reg |= FIELD_GET(DMC620_PMU_COUNTERn_CONTROL_EVENT_MUX,
+ ATTR_CFG_GET_FLD(attr, event));
As a cheeky micro-optimisation, consider laying out the relevant fields
in the config word in the same order as the corresponding register
fields, such that the compiler can ultimately optimise this whole lot
together into a single mask/shift operation.
+ return reg;
+}
+
+static int dmc620_get_event_idx(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+ int idx, start_idx, end_idx;
+
+ if (ATTR_CFG_GET_FLD(&event->attr, clkdiv2)) {
+ start_idx = 0;
+ end_idx = DMC620_PMU_CLKDIV2_MAX_COUNTERS;
+ } else {
+ start_idx = DMC620_PMU_CLKDIV2_MAX_COUNTERS;
+ end_idx = DMC620_PMU_MAX_COUNTERS;
+ }
+
+ for (idx = start_idx; idx < end_idx; ++idx) {
+ if (!test_and_set_bit(idx, dmc620_pmu->used_mask))
+ return idx;
+ }
+
+ /* The counters are all in use. */
+ return -EAGAIN;
+}
+
+static u64 dmc620_pmu_read_counter(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+
+ return dmc620_pmu_creg_read(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_VALUE);
+}
Might it be simpler to inline this in its sole caller? I'm not sure it
adds any clarity to have *two* levels of trivial indirection around a
simple register read.
+static void dmc620_pmu_event_update(struct perf_event *event)
+{
+ struct hw_perf_event *hwc = &event->hw;
+ u64 delta, prev_count, new_count;
+
+ do {
+ /* We may also be called from the irq handler */
+ prev_count = local64_read(&hwc->prev_count);
+ new_count = dmc620_pmu_read_counter(event);
+ } while (local64_cmpxchg(&hwc->prev_count,
+ prev_count, new_count) != prev_count);
+ delta = (new_count - prev_count) & DMC620_CNT_MAX_PERIOD;
+ local64_add(delta, &event->count);
+}
+
+static void dmc620_pmu_event_set_period(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+
+ local64_set(&event->hw.prev_count, DMC620_CNT_INIT);
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_VALUE, DMC620_CNT_INIT);
+}
+
+static void dmc620_pmu_enable_counter(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+ struct perf_event_attr *attr = &event->attr;
+ u64 reg;
+
+ reg = ATTR_CFG_GET_FLD(attr, mask);
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_MASK_31_00, lower_32_bits(reg));
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_MASK_63_32, upper_32_bits(reg));
+
+ reg = ATTR_CFG_GET_FLD(attr, match);
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_MATCH_31_00, lower_32_bits(reg));
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_MATCH_63_32, upper_32_bits(reg));
Do the mask and match values have to be rewritten every time, or could
those be set once in event_add() such that you can just toggle the
control register to start and stop the underlying counter?
+ reg = dmc620_event_to_counter_control(event) | DMC620_PMU_COUNTERn_CONTROL_ENABLE;
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_CONTROL, (u32)reg);
+}
+
+static void dmc620_pmu_disable_counter(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+
+ dmc620_pmu_creg_write(dmc620_pmu,
+ event->hw.idx, DMC620_PMU_COUNTERn_CONTROL, 0);
+}
+
+static irqreturn_t dmc620_pmu_handle_irq(int irq_num, void *data)
+{
+ struct dmc620_pmu_irq *irq = data;
+ struct dmc620_pmu *dmc620_pmu;
+ irqreturn_t ret = IRQ_NONE;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(dmc620_pmu, &irq->pmus_node, pmus_node) {
+ unsigned long status;
+ struct perf_event *event;
+ unsigned int idx;
+
+ /*
+ * HW doesn't provide a control to atomically disable all counters.
+ * To prevent race condition, disable all events before continuing
+ */
I'm still doubtful that this doesn't introduce more inaccuracy overall
than whatever it's trying to avoid... :/
+ for (idx = 0; idx < DMC620_PMU_MAX_COUNTERS; idx++) {
+ event = dmc620_pmu->events[idx];
+ if (!event)
+ continue;
+ dmc620_pmu_disable_counter(event);
+ }
+
+ status = readl(dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);
+ status |= (readl(dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK) <<
+ DMC620_PMU_CLKDIV2_MAX_COUNTERS);
+ if (!status)
+ continue;
Oh hey, remember that time you unconditionally disabled all the live
counters on the way in? ;)
+ for_each_set_bit(idx, &status,
+ DMC620_PMU_MAX_COUNTERS) {
+ event = dmc620_pmu->events[idx];
+ if (WARN_ON_ONCE(!event))
+ continue;
+ dmc620_pmu_event_update(event);
+ dmc620_pmu_event_set_period(event);
+ }
+
+ if (status & DMC620_PMU_OVERFLOW_STATUS_CLKDIV2_MASK)
+ writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);
+
+ if ((status >> DMC620_PMU_CLKDIV2_MAX_COUNTERS) &
+ DMC620_PMU_OVERFLOW_STATUS_CLK_MASK)
+ writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK);
+
+ for (idx = 0; idx < DMC620_PMU_MAX_COUNTERS; idx++) {
+ event = dmc620_pmu->events[idx];
+ if (!event)
+ continue;
+ if (!(event->hw.state & PERF_HES_STOPPED))
+ dmc620_pmu_enable_counter(event);
+ }
+
+ ret = IRQ_HANDLED;
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num)
+{
+ struct dmc620_pmu_irq *irq;
+ int ret;
+
+ list_for_each_entry(irq, &dmc620_pmu_irqs, irqs_node)
+ if (irq->irq_num == irq_num && refcount_inc_not_zero(&irq->refcount))
+ return irq;
+
+ irq = kzalloc(sizeof(*irq), GFP_KERNEL);
+ if (!irq)
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&irq->pmus_node);
+
+ /* Pick one CPU to be the preferred one to use */
+ irq->cpu = raw_smp_processor_id();
+ refcount_set(&irq->refcount, 1);
+
+ ret = request_irq(irq_num, dmc620_pmu_handle_irq,
+ IRQF_NOBALANCING | IRQF_NO_THREAD,
+ "dmc620-pmu", irq);
+ if (ret)
+ goto out_free_aff;
+
+ ret = irq_set_affinity_hint(irq_num, cpumask_of(irq->cpu));
+ if (ret)
+ goto out_free_irq;
+
+ ret = cpuhp_state_add_instance_nocalls(cpuhp_state_num, &irq->node);
+ if (ret)
+ goto out_free_irq;
+
+ irq->irq_num = irq_num;
+ list_add(&irq->irqs_node, &dmc620_pmu_irqs);
+
+ return irq;
+
+out_free_irq:
+ free_irq(irq_num, irq);
+out_free_aff:
+ kfree(irq);
+ return ERR_PTR(ret);
+}
+
+static int dmc620_pmu_get_irq(struct dmc620_pmu *dmc620_pmu, int irq_num)
+{
+ struct dmc620_pmu_irq *irq;
+
+ mutex_lock(&dmc620_pmu_irqs_lock);
+ irq = __dmc620_pmu_get_irq(irq_num);
+ mutex_unlock(&dmc620_pmu_irqs_lock);
+
+ if (IS_ERR(irq))
+ return PTR_ERR(irq);
+
+ dmc620_pmu->irq = irq;
+ mutex_lock(&dmc620_pmu_irqs_lock);
+ list_add_rcu(&dmc620_pmu->pmus_node, &irq->pmus_node);
+ mutex_unlock(&dmc620_pmu_irqs_lock);
+
+ return 0;
+}
+
+static void dmc620_pmu_put_irq(struct dmc620_pmu *dmc620_pmu)
+{
+ struct dmc620_pmu_irq *irq = dmc620_pmu->irq;
+
+ mutex_lock(&dmc620_pmu_irqs_lock);
+ list_del_rcu(&dmc620_pmu->pmus_node);
+
+ if (!refcount_dec_and_test(&irq->refcount)) {
+ mutex_unlock(&dmc620_pmu_irqs_lock);
+ return;
+ }
+
+ list_del(&irq->irqs_node);
+ mutex_unlock(&dmc620_pmu_irqs_lock);
+
+ free_irq(irq->irq_num, irq);
+ cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &irq->node);
+ kfree(irq);
+}
+
+static int dmc620_pmu_event_init(struct perf_event *event)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+ struct hw_perf_event *hwc = &event->hw;
+ struct perf_event *sibling;
+
+ if (event->attr.type != event->pmu->type)
+ return -ENOENT;
+
+ /*
+ * DMC 620 PMUs are shared across all cpus and cannot
+ * support task bound and sampling events.
+ */
+ if (is_sampling_event(event) ||
+ event->attach_state & PERF_ATTACH_TASK) {
+ dev_dbg(dmc620_pmu->pmu.dev,
+ "Can't support per-task counters\n");
+ return -EOPNOTSUPP;
+ }
+
+ /*
+ * Many perf core operations (eg. events rotation) operate on a
+ * single CPU context. This is obvious for CPU PMUs, where one
+ * expects the same sets of events being observed on all CPUs,
+ * but can lead to issues for off-core PMUs, where each
+ * event could be theoretically assigned to a different CPU. To
+ * mitigate this, we enforce CPU assignment to one, selected
+ * processor.
+ */
+ event->cpu = dmc620_pmu->irq->cpu;
+ if (event->cpu < 0)
+ return -EINVAL;
+
+ /*
+ * We must NOT create groups containing mixed PMUs, although software
+ * events are acceptable.
+ */
+ if (event->group_leader->pmu != event->pmu &&
+ !is_software_event(event->group_leader))
+ return -EINVAL;
+
+ for_each_sibling_event(sibling, event->group_leader) {
+ if (sibling->pmu != event->pmu &&
+ !is_software_event(sibling))
+ return -EINVAL;
+ }
As before, if you can't start, stop, or read multiple counters
atomically, you can't really support groups of events for this PMU
either. It's impossible to measure accurate ratios with a variable
amount of skew between individual counters.
+ hwc->idx = -1;
+ return 0;
+}
+
+static void dmc620_pmu_read(struct perf_event *event)
+{
+ dmc620_pmu_event_update(event);
+}
+
+static void dmc620_pmu_start(struct perf_event *event, int flags)
+{
+ event->hw.state = 0;
+ dmc620_pmu_event_set_period(event);
+ dmc620_pmu_enable_counter(event);
+}
+
+static void dmc620_pmu_stop(struct perf_event *event, int flags)
+{
+ if (event->hw.state & PERF_HES_STOPPED)
+ return;
+
+ dmc620_pmu_disable_counter(event);
+ dmc620_pmu_event_update(event);
+ event->hw.state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+}
+
+static int dmc620_pmu_add(struct perf_event *event, int flags)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx;
+
+ idx = dmc620_get_event_idx(event);
+ if (idx < 0)
+ return idx;
+
+ hwc->idx = idx;
+ dmc620_pmu->events[idx] = event;
+ hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+
+ if (flags & PERF_EF_START)
+ dmc620_pmu_start(event, PERF_EF_RELOAD);
+
+ perf_event_update_userpage(event);
+ return 0;
+}
+
+static void dmc620_pmu_del(struct perf_event *event, int flags)
+{
+ struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx = hwc->idx;
+
+ dmc620_pmu_stop(event, PERF_EF_UPDATE);
+ dmc620_pmu->events[idx] = NULL;
+ clear_bit(idx, dmc620_pmu->used_mask);
+ perf_event_update_userpage(event);
+}
+
+static int dmc620_pmu_cpu_teardown(unsigned int cpu,
+ struct hlist_node *node)
+{
+ struct dmc620_pmu_irq *irq;
+ struct dmc620_pmu *dmc620_pmu;
+ unsigned int target;
+
+ irq = hlist_entry_safe(node, struct dmc620_pmu_irq, node);
+ if (cpu != irq->cpu)
+ return 0;
+
+ target = cpumask_any_but(cpu_online_mask, cpu);
+ if (target >= nr_cpu_ids)
+ return 0;
+
+ /* We're only reading, but this isn't the place to be involving RCU */
+ mutex_lock(&dmc620_pmu_irqs_lock);
+ list_for_each_entry(dmc620_pmu, &irq->pmus_node, pmus_node)
+ perf_pmu_migrate_context(&dmc620_pmu->pmu, irq->cpu, target);
+ mutex_unlock(&dmc620_pmu_irqs_lock);
+
+ WARN_ON(irq_set_affinity_hint(irq->irq_num, cpumask_of(target)));
+ irq->cpu = target;
+
+ return 0;
+}
+
+static int dmc620_pmu_device_probe(struct platform_device *pdev)
+{
+ struct dmc620_pmu *dmc620_pmu;
+ struct resource *res;
+ char *name;
+ int irq_num;
+ int i, ret;
+
+ dmc620_pmu = devm_kzalloc(&pdev->dev,
+ sizeof(struct dmc620_pmu), GFP_KERNEL);
+ if (!dmc620_pmu)
+ return -ENOMEM;
+
+ dmc620_pmu->pdev = pdev;
Is this ever used?
+ platform_set_drvdata(pdev, dmc620_pmu);
+
+ dmc620_pmu->pmu = (struct pmu) {
+ .module = THIS_MODULE,
+ .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
+ .task_ctx_nr = perf_invalid_context,
+ .event_init = dmc620_pmu_event_init,
+ .add = dmc620_pmu_add,
+ .del = dmc620_pmu_del,
+ .start = dmc620_pmu_start,
+ .stop = dmc620_pmu_stop,
+ .read = dmc620_pmu_read,
+ .attr_groups = dmc620_pmu_attr_groups,
+ };
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ dmc620_pmu->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(dmc620_pmu->base))
+ return PTR_ERR(dmc620_pmu->base);
+
+ /* Make sure device is reset before enabling interrupt */
+ for (i = 0; i < DMC620_PMU_MAX_COUNTERS; i++)
+ dmc620_pmu_creg_write(dmc620_pmu, i, DMC620_PMU_COUNTERn_CONTROL, 0);
Maybe make sure the overflow registers are clear too?
+ irq_num = platform_get_irq(pdev, 0);
+ if (irq_num < 0)
+ return irq_num;
+
+ ret = dmc620_pmu_get_irq(dmc620_pmu, irq_num);
+ if (ret)
+ return ret;
+
+ name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+ "%s_%llx", DMC620_PMUNAME,
+ (res->start) >> DMC620_PA_SHIFT);
res->start doesn't need parentheses, however I guess it might need
casting to u64 to solve the build warning (I'm not sure there's any
nicer way, unfortunately).
Robin.
+ if (!name) {
+ dev_err(&pdev->dev,
+ "Create name failed, PMU @%pa\n", &res->start);
+ goto out_teardown_dev;
+ }
+
+ ret = perf_pmu_register(&dmc620_pmu->pmu, name, -1);
+ if (ret)
+ goto out_teardown_dev;
+
+ return 0;
+
+out_teardown_dev:
+ dmc620_pmu_put_irq(dmc620_pmu);
+ synchronize_rcu();
+ return ret;
+}
+
+static int dmc620_pmu_device_remove(struct platform_device *pdev)
+{
+ struct dmc620_pmu *dmc620_pmu = platform_get_drvdata(pdev);
+
+ dmc620_pmu_put_irq(dmc620_pmu);
+
+ /* perf will synchronise RCU before devres can free dmc620_pmu */
+ perf_pmu_unregister(&dmc620_pmu->pmu);
+
+ return 0;
+}
+
+static const struct acpi_device_id dmc620_acpi_match[] = {
+ { "ARMHD620", 0},
+ {},
+};
+MODULE_DEVICE_TABLE(acpi, dmc620_acpi_match);
+static struct platform_driver dmc620_pmu_driver = {
+ .driver = {
+ .name = DMC620_DRVNAME,
+ .acpi_match_table = dmc620_acpi_match,
+ },
+ .probe = dmc620_pmu_device_probe,
+ .remove = dmc620_pmu_device_remove,
+};
+
+static int __init dmc620_pmu_init(void)
+{
+ cpuhp_state_num = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
+ DMC620_DRVNAME,
+ NULL,
+ dmc620_pmu_cpu_teardown);
+ if (cpuhp_state_num < 0)
+ return cpuhp_state_num;
+
+ return platform_driver_register(&dmc620_pmu_driver);
+}
+
+static void __exit dmc620_pmu_exit(void)
+{
+ platform_driver_unregister(&dmc620_pmu_driver);
+ cpuhp_remove_multi_state(cpuhp_state_num);
+}
+
+module_init(dmc620_pmu_init);
+module_exit(dmc620_pmu_exit);
+
+MODULE_DESCRIPTION("Perf driver for the ARM DMC-620 memory controller");
+MODULE_AUTHOR("Tuan Phan <tuanphan@xxxxxxxxxxxxxxxxxxxxxx");
+MODULE_LICENSE("GPL v2");