diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 130327ff..3e3a44b 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 && 64BIT)
+	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..40b583e
--- /dev/null
+++ b/drivers/perf/arm_dmc620_pmu.c
@@ -0,0 +1,749 @@
+// 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;
+
+	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_ULL(hi - lo, 0))
+
+#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_PREP(DMC620_PMU_COUNTERn_CONTROL_INVERT,
+			ATTR_CFG_GET_FLD(attr, invert));
+	reg |= FIELD_PREP(DMC620_PMU_COUNTERn_CONTROL_EVENT_MUX,
+			ATTR_CFG_GET_FLD(attr, event));
+	reg |= FIELD_PREP(DMC620_PMU_COUNTERn_CONTROL_INCR_MUX,
+			ATTR_CFG_GET_FLD(attr, incr));
+
+	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 inline
+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);
+}
+
+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);
+	u32 reg;
+
+	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, 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 (overflow happens while clearing status register),
+		 * disable all events before continuing
+		 */
+		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) {
+			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);
+
+	WARN_ON(irq_set_affinity_hint(irq->irq_num, NULL));
+	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 can't atomically disable all HW counters so only one event allowed,
+	 * although software events are acceptable.
+	 */
+	if (event->group_leader != event &&
+			!is_software_event(event->group_leader))
+		return -EINVAL;
+
+	for_each_sibling_event(sibling, event->group_leader) {
+		if (sibling != event &&
+				!is_software_event(sibling))
+			return -EINVAL;
+	}
+
+	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 perf_event_attr *attr = &event->attr;
+	struct hw_perf_event *hwc = &event->hw;
+	int idx;
+	u64 reg;
+
+	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;
+
+	reg = ATTR_CFG_GET_FLD(attr, mask);
+	dmc620_pmu_creg_write(dmc620_pmu,
+			      idx, DMC620_PMU_COUNTERn_MASK_31_00, lower_32_bits(reg));
+	dmc620_pmu_creg_write(dmc620_pmu,
+			      idx, DMC620_PMU_COUNTERn_MASK_63_32, upper_32_bits(reg));
+
+	reg = ATTR_CFG_GET_FLD(attr, match);
+	dmc620_pmu_creg_write(dmc620_pmu,
+			      idx, DMC620_PMU_COUNTERn_MATCH_31_00, lower_32_bits(reg));
+	dmc620_pmu_creg_write(dmc620_pmu,
+			      idx, DMC620_PMU_COUNTERn_MATCH_63_32, upper_32_bits(reg));
+
+	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;
+
+	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);
+	writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);
+	writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK);
+
+	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,
+				  (u64)(res->start >> DMC620_PA_SHIFT));
+	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@os.amperecomputing.com");
+MODULE_LICENSE("GPL v2");
