[RFC V2 3/3] perf: qcom: Add Falkor CPU PMU IMPLEMENTATION DEFINED event support

[Agustin Vega-Frias]

Selection of these events can be envisioned as indexing them from
a 3D matrix:
- the first index selects a Region Event Selection Register (PMRESRx_EL0)
- the second index selects a group from which only one event at a time
  can be selected
- the third index selects the event

The event is encoded into perf_event_attr.config as 0xPRCCG, where:
  P  [config:16   ] = prefix   (flag that indicates a matrix-based event)
  R  [config:12-15] = register (specifies the PMRESRx_EL0 instance)
  G  [config:0-3  ] = group    (specifies the event group)
  CC [config:4-11 ] = code     (specifies the event)

Events with the P flag set to zero are treated as common PMUv3 events
and are directly programmed into PMXEVTYPERx_EL0.

The first two indexes are set combining the RESR and group number with
a base number and writing it into the architected PMXEVTYPER_EL0 register.
The third index is set by writing the code into the bits corresponding
with the group into the appropriate IMPLEMENTATION DEFINED PMRESRx_EL0
register.

Support for this extension is signaled by the presence of the Falkor PMU
device node under each Falkor CPU device node in the DSDT ACPI table. E.g.:

    Device (CPU0)
    {
        Name (_HID, "ACPI0007" /* Processor Device */)
        ...
        Device (PMU0)
        {
            Name (_HID, "QCOM8150") /* Qualcomm Falkor PMU device */
            ...
        }
    }

Signed-off-by: Agustin Vega-Frias <agustinv@xxxxxxxxxxxxxx>
---
 drivers/perf/Makefile       |   2 +-
 drivers/perf/qcom_arm_pmu.c | 310 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 311 insertions(+), 1 deletion(-)
 create mode 100644 drivers/perf/qcom_arm_pmu.c

diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index b3902bd..a61afd9 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -3,7 +3,7 @@ obj-$(CONFIG_ARM_CCI_PMU) += arm-cci.o
 obj-$(CONFIG_ARM_CCN) += arm-ccn.o
 obj-$(CONFIG_ARM_DSU_PMU) += arm_dsu_pmu.o
 obj-$(CONFIG_ARM_PMU) += arm_pmu.o arm_pmu_platform.o
-obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
+obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o qcom_arm_pmu.o
 obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
diff --git a/drivers/perf/qcom_arm_pmu.c b/drivers/perf/qcom_arm_pmu.c
new file mode 100644
index 0000000..5cec756
--- /dev/null
+++ b/drivers/perf/qcom_arm_pmu.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * Qualcomm Technologies CPU PMU IMPLEMENTATION DEFINED extensions support
+ *
+ * Current extensions supported:
+ *
+ * - Matrix-based microarchitectural events support
+ *
+ *   Selection of these events can be envisioned as indexing them from
+ *   a 3D matrix:
+ *   - the first index selects a Region Event Selection Register (PMRESRx_EL0)
+ *   - the second index selects a group from which only one event at a time
+ *     can be selected
+ *   - the third index selects the event
+ *
+ *   The event is encoded into perf_event_attr.config as 0xPRCCG, where:
+ *     P  [config:16   ] = prefix   (flag that indicates a matrix-based event)
+ *     R  [config:12-15] = register (specifies the PMRESRx_EL0 instance)
+ *     G  [config:0-3  ] = group    (specifies the event group)
+ *     CC [config:4-11 ] = code     (specifies the event)
+ *
+ *   Events with the P flag set to zero are treated as common PMUv3 events
+ *   and are directly programmed into PMXEVTYPERx_EL0.
+ *
+ *   The first two indexes are set combining the RESR and group number with
+ *   a base number and writing it into the architected PMXEVTYPER_EL0 register.
+ *   The third index is set by writing the code into the bits corresponding
+ *   with the group into the appropriate IMPLEMENTATION DEFINED PMRESRx_EL0
+ *   register.
+ */
+
+#include <linux/acpi.h>
+#include <linux/perf/arm_pmu.h>
+
+#define pmresr0_el0         sys_reg(3, 5, 11, 3, 0)
+#define pmresr1_el0         sys_reg(3, 5, 11, 3, 2)
+#define pmresr2_el0         sys_reg(3, 5, 11, 3, 4)
+#define pmxevcntcr_el0      sys_reg(3, 5, 11, 0, 3)
+
+#define QC_EVT_PFX_SHIFT    16
+#define QC_EVT_REG_SHIFT    12
+#define QC_EVT_CODE_SHIFT   4
+#define QC_EVT_GRP_SHIFT    0
+#define QC_EVT_PFX_MASK     GENMASK(QC_EVT_PFX_SHIFT,  QC_EVT_PFX_SHIFT)
+#define QC_EVT_REG_MASK     GENMASK(QC_EVT_REG_SHIFT + 3,  QC_EVT_REG_SHIFT)
+#define QC_EVT_CODE_MASK    GENMASK(QC_EVT_CODE_SHIFT + 7, QC_EVT_CODE_SHIFT)
+#define QC_EVT_GRP_MASK     GENMASK(QC_EVT_GRP_SHIFT + 3,  QC_EVT_GRP_SHIFT)
+#define QC_EVT_PRG_MASK     (QC_EVT_PFX_MASK | QC_EVT_REG_MASK | QC_EVT_GRP_MASK)
+#define QC_EVT_PRG(event)   ((event) & QC_EVT_PRG_MASK)
+#define QC_EVT_REG(event)   (((event) & QC_EVT_REG_MASK)  >> QC_EVT_REG_SHIFT)
+#define QC_EVT_CODE(event)  (((event) & QC_EVT_CODE_MASK) >> QC_EVT_CODE_SHIFT)
+#define QC_EVT_GROUP(event) (((event) & QC_EVT_GRP_MASK)  >> QC_EVT_GRP_SHIFT)
+
+#define QC_MAX_GROUP        7
+#define QC_MAX_RESR         2
+#define QC_BITS_PER_GROUP   8
+#define QC_RESR_ENABLE      BIT_ULL(63)
+#define QC_RESR_EVT_BASE    0xd8
+
+static struct arm_pmu *def_ops;
+
+static inline void falkor_write_pmresr(u64 reg, u64 val)
+{
+	if (reg == 0)
+		write_sysreg_s(val, pmresr0_el0);
+	else if (reg == 1)
+		write_sysreg_s(val, pmresr1_el0);
+	else
+		write_sysreg_s(val, pmresr2_el0);
+}
+
+static inline u64 falkor_read_pmresr(u64 reg)
+{
+	return (reg == 0 ? read_sysreg_s(pmresr0_el0) :
+		reg == 1 ? read_sysreg_s(pmresr1_el0) :
+			   read_sysreg_s(pmresr2_el0));
+}
+
+static void falkor_set_resr(u64 reg, u64 group, u64 code)
+{
+	u64 shift = group * QC_BITS_PER_GROUP;
+	u64 mask = GENMASK(shift + QC_BITS_PER_GROUP - 1, shift);
+	u64 val;
+
+	val = falkor_read_pmresr(reg) & ~mask;
+	val |= (code << shift);
+	val |= QC_RESR_ENABLE;
+	falkor_write_pmresr(reg, val);
+}
+
+static void falkor_clear_resr(u64 reg, u64 group)
+{
+	u32 shift = group * QC_BITS_PER_GROUP;
+	u64 mask = GENMASK(shift + QC_BITS_PER_GROUP - 1, shift);
+	u64 val = falkor_read_pmresr(reg) & ~mask;
+
+	falkor_write_pmresr(reg, val == QC_RESR_ENABLE ? 0 : val);
+}
+
+/*
+ * Check if e1 and e2 conflict with each other
+ *
+ * e1 is a matrix-based microarchitectural event we are checking against e2.
+ * A conflict exists if the events use the same reg, group, and a different
+ * code. Events with the same code are allowed because they could be using
+ * different filters (e.g. one to count user space and the other to count
+ * kernel space events).
+ */
+static inline int events_conflict(struct perf_event *e1, struct perf_event *e2)
+{
+	if ((e1 != e2) &&
+	    (e1->pmu == e2->pmu) &&
+	    (QC_EVT_PRG(e1->attr.config) == QC_EVT_PRG(e2->attr.config)) &&
+	    (QC_EVT_CODE(e1->attr.config) != QC_EVT_CODE(e2->attr.config))) {
+		pr_debug_ratelimited(
+			"Group exclusion: conflicting events %llx %llx\n",
+			e1->attr.config,
+			e2->attr.config);
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Check if the given event is valid for the PMU and if so return the value
+ * that can be used in PMXEVTYPER_EL0 to select the event
+ */
+static int falkor_map_event(struct perf_event *event)
+{
+	u64 reg = QC_EVT_REG(event->attr.config);
+	u64 group = QC_EVT_GROUP(event->attr.config);
+	struct perf_event *leader;
+	struct perf_event *sibling;
+
+	if (!(event->attr.config & QC_EVT_PFX_MASK))
+		/* Common PMUv3 event, forward to the original op */
+		return def_ops->map_event(event);
+
+	/* Is it a valid matrix event? */
+	if ((group > QC_MAX_GROUP) || (reg > QC_MAX_RESR))
+		return -ENOENT;
+
+	/* If part of an event group, check if the event can be put in it */
+
+	leader = event->group_leader;
+	if (events_conflict(event, leader))
+		return -ENOENT;
+
+	for_each_sibling_event(sibling, leader)
+		if (events_conflict(event, sibling))
+			return -ENOENT;
+
+	return QC_RESR_EVT_BASE + reg*8 + group;
+}
+
+/*
+ * Find a slot for the event on the current CPU
+ */
+static int falkor_get_event_idx(struct pmu_hw_events *cpuc, struct perf_event *event)
+{
+	int idx;
+
+	if (!!(event->attr.config & QC_EVT_PFX_MASK))
+		/* Matrix event, check for conflicts with existing events */
+		for_each_set_bit(idx, cpuc->used_mask, ARMPMU_MAX_HWEVENTS)
+			if (cpuc->events[idx] &&
+			    events_conflict(event, cpuc->events[idx]))
+				return -ENOENT;
+
+	/* Let the original op handle the rest */
+	idx = def_ops->get_event_idx(cpuc, event);
+
+	/*
+	 * This is called for actually allocating the events, but also with
+	 * a dummy pmu_hw_events when validating groups, for that case we
+	 * need to ensure that cpuc->events[idx] is NULL so we don't use
+	 * an uninitialized pointer. Conflicts for matrix events in groups
+	 * are checked during event mapping anyway (see falkor_event_map).
+	 */
+	cpuc->events[idx] = NULL;
+
+	return idx;
+}
+
+/*
+ * Reset the PMU
+ */
+static void falkor_reset(void *info)
+{
+	struct arm_pmu *pmu = (struct arm_pmu *)info;
+	u32 i, ctrs = pmu->num_events;
+
+	/* PMRESRx_EL0 regs are unknown at reset, except for the EN field */
+	for (i = 0; i <= QC_MAX_RESR; i++)
+		falkor_write_pmresr(i, 0);
+
+	/* PMXEVCNTCRx_EL0 regs are unknown at reset */
+	for (i = 0; i <= ctrs; i++) {
+		write_sysreg(i, pmselr_el0);
+		isb();
+		write_sysreg_s(0, pmxevcntcr_el0);
+	}
+
+	/* Let the original op handle the rest */
+	def_ops->reset(info);
+}
+
+/*
+ * Enable the given event
+ */
+static void falkor_enable(struct perf_event *event)
+{
+	if (!!(event->attr.config & QC_EVT_PFX_MASK)) {
+		/* Matrix event, program the appropriate PMRESRx_EL0 */
+		struct arm_pmu *pmu = to_arm_pmu(event->pmu);
+		struct pmu_hw_events *events = this_cpu_ptr(pmu->hw_events);
+		u64 reg = QC_EVT_REG(event->attr.config);
+		u64 code = QC_EVT_CODE(event->attr.config);
+		u64 group = QC_EVT_GROUP(event->attr.config);
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&events->pmu_lock, flags);
+		falkor_set_resr(reg, group, code);
+		raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	}
+
+	/* Let the original op handle the rest */
+	def_ops->enable(event);
+}
+
+/*
+ * Disable the given event
+ */
+static void falkor_disable(struct perf_event *event)
+{
+	/* Use the original op to disable the counter and interrupt  */
+	def_ops->enable(event);
+
+	if (!!(event->attr.config & QC_EVT_PFX_MASK)) {
+		/* Matrix event, de-program the appropriate PMRESRx_EL0 */
+		struct arm_pmu *pmu = to_arm_pmu(event->pmu);
+		struct pmu_hw_events *events = this_cpu_ptr(pmu->hw_events);
+		u64 reg = QC_EVT_REG(event->attr.config);
+		u64 group = QC_EVT_GROUP(event->attr.config);
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&events->pmu_lock, flags);
+		falkor_clear_resr(reg, group);
+		raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	}
+}
+
+PMU_FORMAT_ATTR(event,  "config:0-15");
+PMU_FORMAT_ATTR(prefix, "config:16");
+PMU_FORMAT_ATTR(reg,    "config:12-15");
+PMU_FORMAT_ATTR(code,   "config:4-11");
+PMU_FORMAT_ATTR(group,  "config:0-3");
+
+static struct attribute *falkor_pmu_formats[] = {
+	&format_attr_event.attr,
+	&format_attr_prefix.attr,
+	&format_attr_reg.attr,
+	&format_attr_code.attr,
+	&format_attr_group.attr,
+	NULL,
+};
+
+static struct attribute_group falkor_pmu_format_attr_group = {
+	.name = "format",
+	.attrs = falkor_pmu_formats,
+};
+
+static int qcom_falkor_pmu_init(struct arm_pmu *pmu, struct device *dev)
+{
+	/* Save base arm_pmu so we can invoke its ops when appropriate */
+	def_ops = devm_kmemdup(dev, pmu, sizeof(*def_ops), GFP_KERNEL);
+	if (!def_ops) {
+		pr_warn("Failed to allocate arm_pmu for QCOM extensions");
+		return -ENODEV;
+	}
+
+	pmu->name = "qcom_pmuv3";
+
+	/* Override the necessary ops */
+	pmu->map_event     = falkor_map_event;
+	pmu->get_event_idx = falkor_get_event_idx;
+	pmu->reset         = falkor_reset;
+	pmu->enable        = falkor_enable;
+	pmu->disable       = falkor_disable;
+
+	/* Override the necessary attributes */
+	pmu->pmu.attr_groups[ARMPMU_ATTR_GROUP_FORMATS] =
+		&falkor_pmu_format_attr_group;
+
+	return 1;
+}
+
+ACPI_DECLARE_PMU_VARIANT(qcom_falkor, "QCOM8150", qcom_falkor_pmu_init);
-- 
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.