Adds perf events support for L2 cache PMU.

The L2 cache PMU driver is named 'l2cache_0' and can be used
with perf events to profile L2 events such as cache hits
and misses.

Signed-off-by: Neil Leeder <nlee...@codeaurora.org>
---
v6: restore accidentally dropped Kconfig dependencies

v5:
Fold the header and l2-accessors into .c file
Use multi-instance framework for hotplug
Change terminology from slice to cluster for clarity
Remove unnecessary rmw sequence for enable registers
Use prev_count in hwc rather than in slice
Enforce all events in same group on same CPU
Add comments, rename variables for clarity

v4:
Replace notifier with hotplug statemachine
Allocate PMU struct dynamically

v3:
Remove exports from l2-accessors
Change l2-accessors Kconfig to make it not user-selectable
Reorder and remove unnecessary includes

v2:
Add the l2-accessors patch to this patchset, previously posted separately.
Remove sampling and per-task functionality for this uncore PMU.
Use cpumask to replace code which filtered events to one cpu per slice.
Replace manual event filtering with filter_match callback.
Use a separate used_mask for event groups.
Add hotplug notifier for CPU and irq migration.
Remove extraneous synchronisation instructions.
Other miscellaneous cleanup.

 drivers/soc/qcom/Kconfig         |   9 +
 drivers/soc/qcom/Makefile        |   1 +
 drivers/soc/qcom/perf_event_l2.c | 948 +++++++++++++++++++++++++++++++++++++++
 include/linux/cpuhotplug.h       |   1 +
 4 files changed, 959 insertions(+)
 create mode 100644 drivers/soc/qcom/perf_event_l2.c

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 461b387..3fa27a8 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -10,6 +10,15 @@ config QCOM_GSBI
           functions for connecting the underlying serial UART, SPI, and I2C
           devices to the output pins.
 
+config QCOM_PERF_EVENTS_L2
+       bool "Qualcomm Technologies L2-cache perf events"
+       depends on ARCH_QCOM && ARM64 && HW_PERF_EVENTS && ACPI
+         help
+         Provides support for the L2 cache performance monitor unit (PMU)
+         in Qualcomm Technologies processors.
+         Adds the L2 cache PMU into the perf events subsystem for
+         monitoring L2 cache events.
+
 config QCOM_PM
        bool "Qualcomm Power Management"
        depends on ARCH_QCOM && !ARM64
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index fdd664e..4c9df3b 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_QCOM_GSBI)        +=      qcom_gsbi.o
+obj-$(CONFIG_QCOM_PERF_EVENTS_L2)      += perf_event_l2.o
 obj-$(CONFIG_QCOM_PM)  +=      spm.o
 obj-$(CONFIG_QCOM_SMD) +=      smd.o
 obj-$(CONFIG_QCOM_SMD_RPM)     += smd-rpm.o
diff --git a/drivers/soc/qcom/perf_event_l2.c b/drivers/soc/qcom/perf_event_l2.c
new file mode 100644
index 0000000..bbf47c9
--- /dev/null
+++ b/drivers/soc/qcom/perf_event_l2.c
@@ -0,0 +1,948 @@
+/* Copyright (c) 2015,2016 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.
+ */
+#include <linux/acpi.h>
+#include <linux/interrupt.h>
+#include <linux/perf_event.h>
+#include <linux/platform_device.h>
+
+#define MAX_L2_CTRS             9
+
+#define L2PMCR_NUM_EV_SHIFT     11
+#define L2PMCR_NUM_EV_MASK      0x1F
+
+#define L2PMCR                  0x400
+#define L2PMCNTENCLR            0x403
+#define L2PMCNTENSET            0x404
+#define L2PMINTENCLR            0x405
+#define L2PMINTENSET            0x406
+#define L2PMOVSCLR              0x407
+#define L2PMOVSSET              0x408
+#define L2PMCCNTCR              0x409
+#define L2PMCCNTR               0x40A
+#define L2PMCCNTSR              0x40C
+#define L2PMRESR                0x410
+#define IA_L2PMXEVCNTCR_BASE    0x420
+#define IA_L2PMXEVCNTR_BASE     0x421
+#define IA_L2PMXEVFILTER_BASE   0x423
+#define IA_L2PMXEVTYPER_BASE    0x424
+
+#define IA_L2_REG_OFFSET        0x10
+
+#define L2PMXEVFILTER_SUFILTER_ALL      0x000E0000
+#define L2PMXEVFILTER_ORGFILTER_IDINDEP 0x00000004
+#define L2PMXEVFILTER_ORGFILTER_ALL     0x00000003
+
+#define L2PM_CC_ENABLE          0x80000000
+
+#define L2EVTYPER_REG_SHIFT     3
+
+#define L2PMRESR_GROUP_BITS     8
+#define L2PMRESR_GROUP_MASK     GENMASK(7, 0)
+
+#define L2CYCLE_CTR_BIT         31
+#define L2CYCLE_CTR_RAW_CODE    0xFE
+
+#define L2PMCR_RESET_ALL        0x6
+#define L2PMCR_COUNTERS_ENABLE  0x1
+#define L2PMCR_COUNTERS_DISABLE 0x0
+
+#define L2PMRESR_EN             ((u64)1 << 63)
+
+#define L2_EVT_MASK             0x00000FFF
+#define L2_EVT_CODE_MASK        0x00000FF0
+#define L2_EVT_GRP_MASK         0x0000000F
+#define L2_EVT_CODE_SHIFT       4
+#define L2_EVT_GRP_SHIFT        0
+
+#define L2_EVT_CODE(event)   (((event) & L2_EVT_CODE_MASK) >> 
L2_EVT_CODE_SHIFT)
+#define L2_EVT_GROUP(event)  (((event) & L2_EVT_GRP_MASK) >> L2_EVT_GRP_SHIFT)
+
+#define L2_EVT_GROUP_MAX        7
+
+#define L2_MAX_PERIOD           U32_MAX
+#define L2_CNT_PERIOD           (U32_MAX - GENMASK(26, 0))
+
+#define L2CPUSRSELR_EL1         S3_3_c15_c0_6
+#define L2CPUSRDR_EL1           S3_3_c15_c0_7
+
+static DEFINE_RAW_SPINLOCK(l2_access_lock);
+
+/**
+ * set_l2_indirect_reg: write value to an L2 register
+ * @reg: Address of L2 register.
+ * @value: Value to be written to register.
+ *
+ * Use architecturally required barriers for ordering between system register
+ * accesses
+ */
+static void set_l2_indirect_reg(u64 reg, u64 val)
+{
+       unsigned long flags;
+
+       raw_spin_lock_irqsave(&l2_access_lock, flags);
+       write_sysreg(reg, L2CPUSRSELR_EL1);
+       isb();
+       write_sysreg(val, L2CPUSRDR_EL1);
+       isb();
+       raw_spin_unlock_irqrestore(&l2_access_lock, flags);
+}
+
+/**
+ * get_l2_indirect_reg: read an L2 register value
+ * @reg: Address of L2 register.
+ *
+ * Use architecturally required barriers for ordering between system register
+ * accesses
+ */
+static u64 get_l2_indirect_reg(u64 reg)
+{
+       u64 val;
+       unsigned long flags;
+
+       raw_spin_lock_irqsave(&l2_access_lock, flags);
+       write_sysreg(reg, L2CPUSRSELR_EL1);
+       isb();
+       val = read_sysreg(L2CPUSRDR_EL1);
+       raw_spin_unlock_irqrestore(&l2_access_lock, flags);
+
+       return val;
+}
+
+/*
+ * Aggregate PMU. Implements the core pmu functions and manages
+ * the hardware PMUs.
+ */
+struct l2cache_pmu {
+       struct hlist_node node;
+       u32 num_pmus;
+       struct pmu pmu;
+       int num_counters;
+       cpumask_t cpumask;
+       struct platform_device *pdev;
+};
+
+/*
+ * The cache is made up of one or more clusters, each cluster has its own PMU.
+ * Each cluster is associated with one or more CPUs.
+ * This structure represents one of the hardware PMUs.
+ *
+ * Events can be envisioned as a 2-dimensional array. Each column represents
+ * a group of events. There are 8 groups. Only one entry from each
+ * group can be in use at a time. When an event is assigned a counter
+ * by *_event_add(), the counter index is assigned to group_to_counter[group].
+ * This allows *filter_match() to detect and reject conflicting events in
+ * the same group.
+ * Events are specified as 0xCCG, where CC is 2 hex digits specifying
+ * the code (array row) and G specifies the group (column).
+ *
+ * In addition there is a cycle counter event specified by L2CYCLE_CTR_RAW_CODE
+ * which is outside the above scheme.
+ */
+struct hml2_pmu {
+       struct perf_event *events[MAX_L2_CTRS];
+       struct l2cache_pmu *l2cache_pmu;
+       DECLARE_BITMAP(used_counters, MAX_L2_CTRS);
+       DECLARE_BITMAP(used_groups, L2_EVT_GROUP_MAX + 1);
+       int group_to_counter[L2_EVT_GROUP_MAX + 1];
+       int irq;
+       /* The CPU that is used for collecting events on this cluster */
+       int on_cpu;
+       /* All the CPUs associated with this cluster */
+       cpumask_t cluster_cpus;
+       spinlock_t pmu_lock;
+};
+
+#define to_l2cache_pmu(p) (container_of(p, struct l2cache_pmu, pmu))
+
+static DEFINE_PER_CPU(struct hml2_pmu *, pmu_cluster);
+static u32 l2_cycle_ctr_idx;
+static u32 l2_counter_present_mask;
+
+static inline u32 idx_to_reg_bit(u32 idx)
+{
+       if (idx == l2_cycle_ctr_idx)
+               return BIT(L2CYCLE_CTR_BIT);
+
+       return BIT(idx);
+}
+
+static inline struct hml2_pmu *get_hml2_pmu(int cpu)
+{
+       return per_cpu(pmu_cluster, cpu);
+}
+
+static void hml2_pmu__reset_on_cluster(void *x)
+{
+       /* Reset all ctrs */
+       set_l2_indirect_reg(L2PMCR, L2PMCR_RESET_ALL);
+       set_l2_indirect_reg(L2PMCNTENCLR, l2_counter_present_mask);
+       set_l2_indirect_reg(L2PMINTENCLR, l2_counter_present_mask);
+       set_l2_indirect_reg(L2PMOVSCLR, l2_counter_present_mask);
+}
+
+static inline void hml2_pmu__reset(struct hml2_pmu *cluster)
+{
+       cpumask_t *mask = &cluster->cluster_cpus;
+
+       if (smp_call_function_any(mask, hml2_pmu__reset_on_cluster, NULL, 1))
+               dev_err(&cluster->l2cache_pmu->pdev->dev,
+                       "Failed to reset on cluster with cpu %d\n",
+                       cpumask_first(&cluster->cluster_cpus));
+}
+
+static inline void hml2_pmu__enable(void)
+{
+       set_l2_indirect_reg(L2PMCR, L2PMCR_COUNTERS_ENABLE);
+}
+
+static inline void hml2_pmu__disable(void)
+{
+       set_l2_indirect_reg(L2PMCR, L2PMCR_COUNTERS_DISABLE);
+}
+
+static inline void hml2_pmu__counter_set_value(u32 idx, u64 value)
+{
+       u32 counter_reg;
+
+       if (idx == l2_cycle_ctr_idx) {
+               set_l2_indirect_reg(L2PMCCNTR, value);
+       } else {
+               counter_reg = (idx * IA_L2_REG_OFFSET) + IA_L2PMXEVCNTR_BASE;
+               set_l2_indirect_reg(counter_reg, value & GENMASK(31, 0));
+       }
+}
+
+static inline u64 hml2_pmu__counter_get_value(u32 idx)
+{
+       u64 value;
+       u32 counter_reg;
+
+       if (idx == l2_cycle_ctr_idx) {
+               value = get_l2_indirect_reg(L2PMCCNTR);
+       } else {
+               counter_reg = (idx * IA_L2_REG_OFFSET) + IA_L2PMXEVCNTR_BASE;
+               value = get_l2_indirect_reg(counter_reg);
+       }
+
+       return value;
+}
+
+static inline void hml2_pmu__counter_enable(u32 idx)
+{
+       set_l2_indirect_reg(L2PMCNTENSET, idx_to_reg_bit(idx));
+}
+
+static inline void hml2_pmu__counter_disable(u32 idx)
+{
+       set_l2_indirect_reg(L2PMCNTENCLR, idx_to_reg_bit(idx));
+}
+
+static inline void hml2_pmu__counter_enable_interrupt(u32 idx)
+{
+       set_l2_indirect_reg(L2PMINTENSET, idx_to_reg_bit(idx));
+}
+
+static inline void hml2_pmu__counter_disable_interrupt(u32 idx)
+{
+       set_l2_indirect_reg(L2PMINTENCLR, idx_to_reg_bit(idx));
+}
+
+static inline void hml2_pmu__set_evccntcr(u32 val)
+{
+       set_l2_indirect_reg(L2PMCCNTCR, val);
+}
+
+static inline void hml2_pmu__set_evcntcr(u32 ctr, u32 val)
+{
+       u32 evtcr_reg = (ctr * IA_L2_REG_OFFSET) + IA_L2PMXEVCNTCR_BASE;
+
+       set_l2_indirect_reg(evtcr_reg, val);
+}
+
+static inline void hml2_pmu__set_evtyper(u32 ctr, u32 val)
+{
+       u32 evtype_reg = (ctr * IA_L2_REG_OFFSET) + IA_L2PMXEVTYPER_BASE;
+
+       set_l2_indirect_reg(evtype_reg, val);
+}
+
+static void hml2_pmu__set_resr(struct hml2_pmu *cluster,
+                              u32 event_group, u32 event_cc)
+{
+       u64 field;
+       u64 resr_val;
+       u32 shift;
+       unsigned long flags;
+
+       shift = L2PMRESR_GROUP_BITS * event_group;
+       field = ((u64)(event_cc & L2PMRESR_GROUP_MASK) << shift) | L2PMRESR_EN;
+
+       spin_lock_irqsave(&cluster->pmu_lock, flags);
+
+       resr_val = get_l2_indirect_reg(L2PMRESR);
+       resr_val &= ~(L2PMRESR_GROUP_MASK << shift);
+       resr_val |= field;
+       set_l2_indirect_reg(L2PMRESR, resr_val);
+
+       spin_unlock_irqrestore(&cluster->pmu_lock, flags);
+}
+
+/*
+ * Hardware allows filtering of events based on the originating
+ * CPU. Turn this off by setting filter bits to allow events from
+ * all CPUS, subunits and ID independent events in this cluster.
+ */
+static inline void hml2_pmu__set_evfilter_sys_mode(u32 ctr)
+{
+       u32 reg = (ctr * IA_L2_REG_OFFSET) + IA_L2PMXEVFILTER_BASE;
+       u32 val =  L2PMXEVFILTER_SUFILTER_ALL |
+                  L2PMXEVFILTER_ORGFILTER_IDINDEP |
+                  L2PMXEVFILTER_ORGFILTER_ALL;
+
+       set_l2_indirect_reg(reg, val);
+}
+
+static inline u32 hml2_pmu__getreset_ovsr(void)
+{
+       u32 result = get_l2_indirect_reg(L2PMOVSSET);
+
+       set_l2_indirect_reg(L2PMOVSCLR, result);
+       return result;
+}
+
+static inline bool hml2_pmu__has_overflowed(u32 ovsr)
+{
+       return !!(ovsr & l2_counter_present_mask);
+}
+
+static inline bool hml2_pmu__counter_has_overflowed(u32 ovsr, u32 idx)
+{
+       return !!(ovsr & idx_to_reg_bit(idx));
+}
+
+static void l2_cache__event_update_from_cluster(struct perf_event *event,
+                                               struct hml2_pmu *cluster)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       u64 delta64, prev, now;
+       u32 delta;
+       u32 idx = hwc->idx;
+
+       do {
+               prev = local64_read(&hwc->prev_count);
+               now = hml2_pmu__counter_get_value(idx);
+       } while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);
+
+       if (idx == l2_cycle_ctr_idx) {
+               /*
+                * The cycle counter is 64-bit so needs separate handling
+                * of 64-bit delta.
+                */
+               delta64 = now - prev;
+               local64_add(delta64, &event->count);
+       } else {
+               /*
+                * 32-bit counters need the unsigned 32-bit math to handle
+                * overflow and now < prev
+                */
+               delta = now - prev;
+               local64_add(delta, &event->count);
+       }
+}
+
+static void l2_cache__cluster_set_period(struct hml2_pmu *cluster,
+                                      struct hw_perf_event *hwc)
+{
+       u64 base = L2_MAX_PERIOD - (L2_CNT_PERIOD - 1);
+       u32 idx = hwc->idx;
+       u64 prev = local64_read(&hwc->prev_count);
+       u64 value;
+
+       /*
+        * Limit the maximum period to prevent the counter value
+        * from overtaking the one we are about to program.
+        * Use a starting value which is high enough that after
+        * an overflow, interrupt latency will not cause the count
+        * to reach the base value. If the previous value
+        * is below the base, increase it to be above the base
+        * and update prev_count accordingly. Otherwise if
+        * the previous value is already above the base
+        * nothing needs to be done to prev_count.
+        */
+       if (prev < base) {
+               value = base + prev;
+               local64_set(&hwc->prev_count, value);
+       } else {
+               value = prev;
+       }
+
+       hml2_pmu__counter_set_value(idx, value);
+}
+
+static int l2_cache__get_event_idx(struct hml2_pmu *cluster,
+                                  struct perf_event *event)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       int idx;
+
+       if (hwc->config_base == L2CYCLE_CTR_RAW_CODE) {
+               if (test_and_set_bit(l2_cycle_ctr_idx, cluster->used_counters))
+                       return -EAGAIN;
+
+               return l2_cycle_ctr_idx;
+       }
+
+       for (idx = 0; idx < cluster->l2cache_pmu->num_counters - 1; idx++) {
+               if (!test_and_set_bit(idx, cluster->used_counters)) {
+                       set_bit(L2_EVT_GROUP(hwc->config_base),
+                               cluster->used_groups);
+                       return idx;
+               }
+       }
+
+       /* The counters are all in use. */
+       return -EAGAIN;
+}
+
+static void l2_cache__clear_event_idx(struct hml2_pmu *cluster,
+                                     struct perf_event *event)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       int idx = hwc->idx;
+
+       clear_bit(idx, cluster->used_counters);
+       if (hwc->config_base != L2CYCLE_CTR_RAW_CODE)
+               clear_bit(L2_EVT_GROUP(hwc->config_base), cluster->used_groups);
+}
+
+static irqreturn_t l2_cache__handle_irq(int irq_num, void *data)
+{
+       struct hml2_pmu *cluster = data;
+       int num_counters = cluster->l2cache_pmu->num_counters;
+       u32 ovsr;
+       int idx;
+
+       ovsr = hml2_pmu__getreset_ovsr();
+       if (!hml2_pmu__has_overflowed(ovsr))
+               return IRQ_NONE;
+
+       for_each_set_bit(idx, cluster->used_counters, num_counters) {
+               struct perf_event *event = cluster->events[idx];
+               struct hw_perf_event *hwc;
+
+               if (!hml2_pmu__counter_has_overflowed(ovsr, idx))
+                       continue;
+
+               l2_cache__event_update_from_cluster(event, cluster);
+               hwc = &event->hw;
+
+               l2_cache__cluster_set_period(cluster, hwc);
+       }
+
+       return IRQ_HANDLED;
+}
+
+/*
+ * Implementation of abstract pmu functionality required by
+ * the core perf events code.
+ */
+
+static void l2_cache__pmu_enable(struct pmu *pmu)
+{
+       /*
+        * Although there is only one PMU (per socket) controlling multiple
+        * physical PMUs (per cluster), because we do not support per-task mode
+        * each event is associated with a CPU. Each event has pmu_enable
+        * called on its CPU, so here it is only necessary to enable the
+        * counters for the current CPU.
+        */
+
+       hml2_pmu__enable();
+}
+
+static void l2_cache__pmu_disable(struct pmu *pmu)
+{
+       hml2_pmu__disable();
+}
+
+static int l2_cache__event_init(struct perf_event *event)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       struct hml2_pmu *cluster;
+       struct perf_event *sibling;
+       struct l2cache_pmu *l2cache_pmu;
+
+       if (event->attr.type != event->pmu->type)
+               return -ENOENT;
+
+       l2cache_pmu = to_l2cache_pmu(event->pmu);
+
+       if (hwc->sample_period) {
+               dev_warn(&l2cache_pmu->pdev->dev, "Sampling not supported\n");
+               return -EOPNOTSUPP;
+       }
+
+       if (event->cpu < 0) {
+               dev_warn(&l2cache_pmu->pdev->dev, "Per-task mode not 
supported\n");
+               return -EOPNOTSUPP;
+       }
+
+       /* We cannot filter accurately so we just don't allow it. */
+       if (event->attr.exclude_user || event->attr.exclude_kernel ||
+           event->attr.exclude_hv || event->attr.exclude_idle) {
+               dev_warn(&l2cache_pmu->pdev->dev, "Can't exclude execution 
levels\n");
+               return -EOPNOTSUPP;
+       }
+
+       if (((L2_EVT_GROUP(event->attr.config) > L2_EVT_GROUP_MAX) ||
+            ((event->attr.config & ~L2_EVT_MASK) != 0)) &&
+           (event->attr.config != L2CYCLE_CTR_RAW_CODE)) {
+               dev_warn(&l2cache_pmu->pdev->dev, "Invalid config %llx\n",
+                        event->attr.config);
+               return -EINVAL;
+       }
+
+       /* Don't allow groups with mixed PMUs, except for s/w events */
+       if (event->group_leader->pmu != event->pmu &&
+           !is_software_event(event->group_leader)) {
+               dev_warn(&l2cache_pmu->pdev->dev,
+                        "Can't create mixed PMU group\n");
+               return -EINVAL;
+       }
+
+       list_for_each_entry(sibling, &event->group_leader->sibling_list,
+                           group_entry)
+               if (sibling->pmu != event->pmu &&
+                   !is_software_event(sibling)) {
+                       dev_warn(&l2cache_pmu->pdev->dev,
+                                "Can't create mixed PMU group\n");
+                       return -EINVAL;
+               }
+
+       /* Ensure all events in a group are on the same cpu */
+       cluster = get_hml2_pmu(event->cpu);
+       if ((event->group_leader != event) &&
+           (cluster->on_cpu != event->group_leader->cpu)) {
+               dev_warn(&l2cache_pmu->pdev->dev,
+                        "Can't create group on CPUs %d and %d",
+                        event->cpu, event->group_leader->cpu);
+               return -EINVAL;
+       }
+
+       hwc->idx = -1;
+       hwc->config_base = event->attr.config;
+
+       /*
+        * Ensure all events are on the same cpu so all events are in the
+        * same cpu context, to avoid races on pmu_enable etc.
+        */
+       event->cpu = cluster->on_cpu;
+
+       return 0;
+}
+
+static void l2_cache__event_start(struct perf_event *event, int flags)
+{
+       struct hml2_pmu *cluster;
+       struct hw_perf_event *hwc = &event->hw;
+       int idx = hwc->idx;
+       u32 config;
+       u32 event_cc, event_group;
+
+       hwc->state = 0;
+
+       cluster = get_hml2_pmu(event->cpu);
+       l2_cache__cluster_set_period(cluster, hwc);
+
+       if (hwc->config_base == L2CYCLE_CTR_RAW_CODE) {
+               hml2_pmu__set_evccntcr(0x0);
+       } else {
+               config = hwc->config_base;
+               event_cc    = L2_EVT_CODE(config);
+               event_group = L2_EVT_GROUP(config);
+
+               hml2_pmu__set_evcntcr(idx, 0x0);
+               hml2_pmu__set_evtyper(idx, event_group);
+               hml2_pmu__set_resr(cluster, event_group, event_cc);
+               hml2_pmu__set_evfilter_sys_mode(idx);
+       }
+
+       hml2_pmu__counter_enable_interrupt(idx);
+       hml2_pmu__counter_enable(idx);
+}
+
+static void l2_cache__event_stop(struct perf_event *event, int flags)
+{
+       struct hml2_pmu *cluster;
+       struct hw_perf_event *hwc = &event->hw;
+       int idx = hwc->idx;
+
+       if (!(hwc->state & PERF_HES_STOPPED)) {
+               cluster = get_hml2_pmu(event->cpu);
+               hml2_pmu__counter_disable_interrupt(idx);
+               hml2_pmu__counter_disable(idx);
+
+               if (flags & PERF_EF_UPDATE)
+                       l2_cache__event_update_from_cluster(event, cluster);
+               hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+       }
+}
+
+static int l2_cache__event_add(struct perf_event *event, int flags)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       int idx;
+       int err = 0;
+       struct hml2_pmu *cluster;
+
+       cluster = get_hml2_pmu(event->cpu);
+
+       idx = l2_cache__get_event_idx(cluster, event);
+       if (idx < 0) {
+               err = idx;
+               return err;
+       }
+
+       hwc->idx = idx;
+       hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+       cluster->events[idx] = event;
+       cluster->group_to_counter[L2_EVT_GROUP(hwc->config_base)] = idx;
+       local64_set(&hwc->prev_count, 0ULL);
+
+       if (flags & PERF_EF_START)
+               l2_cache__event_start(event, flags);
+
+       /* Propagate changes to the userspace mapping. */
+       perf_event_update_userpage(event);
+
+       return err;
+}
+
+static void l2_cache__event_del(struct perf_event *event, int flags)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       struct hml2_pmu *cluster;
+       int idx = hwc->idx;
+
+       cluster = get_hml2_pmu(event->cpu);
+       l2_cache__event_stop(event, flags | PERF_EF_UPDATE);
+       cluster->events[idx] = NULL;
+       l2_cache__clear_event_idx(cluster, event);
+
+       perf_event_update_userpage(event);
+}
+
+static void l2_cache__event_read(struct perf_event *event)
+{
+       l2_cache__event_update_from_cluster(event, get_hml2_pmu(event->cpu));
+}
+
+static int l2_cache_filter_match(struct perf_event *event)
+{
+       struct hw_perf_event *hwc = &event->hw;
+       struct hml2_pmu *cluster = get_hml2_pmu(event->cpu);
+       unsigned int group = L2_EVT_GROUP(hwc->config_base);
+
+       /* check for column exclusion: group already in use by another event */
+       if (test_bit(group, cluster->used_groups) &&
+           cluster->events[cluster->group_to_counter[group]] != event)
+               return 0;
+
+       return 1;
+}
+
+static ssize_t l2_cache_pmu_cpumask_show(struct device *dev,
+                                        struct device_attribute *attr,
+                                        char *buf)
+{
+       struct l2cache_pmu *l2cache_pmu = to_l2cache_pmu(dev_get_drvdata(dev));
+
+       return cpumap_print_to_pagebuf(true, buf, &l2cache_pmu->cpumask);
+}
+
+static struct device_attribute l2_cache_pmu_cpumask_attr =
+               __ATTR(cpumask, S_IRUGO, l2_cache_pmu_cpumask_show, NULL);
+
+static struct attribute *l2_cache_pmu_cpumask_attrs[] = {
+       &l2_cache_pmu_cpumask_attr.attr,
+       NULL,
+};
+
+static struct attribute_group l2_cache_pmu_cpumask_group = {
+       .attrs = l2_cache_pmu_cpumask_attrs,
+};
+
+/* CCG format for perf RAW codes. */
+PMU_FORMAT_ATTR(l2_code,   "config:4-11");
+PMU_FORMAT_ATTR(l2_group,  "config:0-3");
+static struct attribute *l2_cache_pmu_formats[] = {
+       &format_attr_l2_code.attr,
+       &format_attr_l2_group.attr,
+       NULL,
+};
+
+static struct attribute_group l2_cache_pmu_format_group = {
+       .name = "format",
+       .attrs = l2_cache_pmu_formats,
+};
+
+static const struct attribute_group *l2_cache_pmu_attr_grps[] = {
+       &l2_cache_pmu_format_group,
+       &l2_cache_pmu_cpumask_group,
+       NULL,
+};
+
+/*
+ * Generic device handlers
+ */
+
+static const struct acpi_device_id l2_cache_pmu_acpi_match[] = {
+       { "QCOM8130", },
+       { }
+};
+
+static int get_num_counters(void)
+{
+       int val;
+
+       val = get_l2_indirect_reg(L2PMCR);
+
+       /*
+        * Read number of counters from L2PMCR and add 1
+        * for the cycle counter.
+        */
+       return ((val >> L2PMCR_NUM_EV_SHIFT) & L2PMCR_NUM_EV_MASK) + 1;
+}
+
+static int l2cache_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
+{
+       struct hml2_pmu *cluster;
+       cpumask_t cluster_online_cpus;
+       struct l2cache_pmu *l2cache_pmu;
+
+       l2cache_pmu = hlist_entry_safe(node, struct l2cache_pmu, node);
+       cluster = get_hml2_pmu(cpu);
+       cpumask_and(&cluster_online_cpus, &cluster->cluster_cpus,
+                   cpu_online_mask);
+
+       if (cpumask_weight(&cluster_online_cpus) == 1) {
+               /* all CPUs on this cluster were down, use this one */
+               cluster->on_cpu = cpu;
+               cpumask_set_cpu(cpu, &l2cache_pmu->cpumask);
+               WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(cpu)));
+       }
+
+       return 0;
+}
+
+static int l2cache_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
+{
+       struct hml2_pmu *cluster;
+       struct l2cache_pmu *l2cache_pmu;
+       cpumask_t cluster_online_cpus;
+       unsigned int target;
+
+       l2cache_pmu = hlist_entry_safe(node, struct l2cache_pmu, node);
+
+       if (!cpumask_test_and_clear_cpu(cpu, &l2cache_pmu->cpumask))
+               return 0;
+       cluster = get_hml2_pmu(cpu);
+       cpumask_and(&cluster_online_cpus, &cluster->cluster_cpus,
+                   cpu_online_mask);
+
+       /* Any other CPU for this cluster which is still online */
+       target = cpumask_any_but(&cluster_online_cpus, cpu);
+       if (target >= nr_cpu_ids)
+               return 0;
+
+       perf_pmu_migrate_context(&l2cache_pmu->pmu, cpu, target);
+       cluster->on_cpu = target;
+       cpumask_set_cpu(target, &l2cache_pmu->cpumask);
+       WARN_ON(irq_set_affinity(cluster->irq, cpumask_of(target)));
+
+       return 0;
+}
+
+static int l2_cache_pmu_probe_cluster(struct device *dev, void *data)
+{
+       struct platform_device *pdev = to_platform_device(dev->parent);
+       struct platform_device *sdev = to_platform_device(dev);
+       struct l2cache_pmu *l2cache_pmu = data;
+       struct hml2_pmu *cluster;
+       struct acpi_device *device;
+       unsigned long fw_cluster_id;
+       int cpu;
+       int err;
+       int irq;
+
+       if (acpi_bus_get_device(ACPI_HANDLE(dev), &device))
+               return -ENODEV;
+
+       if (kstrtol(device->pnp.unique_id, 10, &fw_cluster_id) < 0) {
+               dev_err(&pdev->dev, "unable to read ACPI uid\n");
+               return -ENODEV;
+       }
+
+       irq = platform_get_irq(sdev, 0);
+       if (irq < 0) {
+               dev_err(&pdev->dev,
+                       "Failed to get valid irq for cluster %ld\n",
+                       fw_cluster_id);
+               return irq;
+       }
+
+       cluster = devm_kzalloc(&pdev->dev, sizeof(*cluster), GFP_KERNEL);
+       if (!cluster)
+               return -ENOMEM;
+
+       cluster->l2cache_pmu = l2cache_pmu;
+       for_each_present_cpu(cpu) {
+               if (topology_physical_package_id(cpu) == fw_cluster_id) {
+                       cpumask_set_cpu(cpu, &cluster->cluster_cpus);
+                       per_cpu(pmu_cluster, cpu) = cluster;
+               }
+       }
+       cluster->irq = irq;
+
+       if (cpumask_empty(&cluster->cluster_cpus)) {
+               dev_err(&pdev->dev, "No CPUs found for L2 cache instance %ld\n",
+                       fw_cluster_id);
+               return -ENODEV;
+       }
+
+       /* Pick one CPU to be the preferred one to use in the cluster */
+       cluster->on_cpu = cpumask_first(&cluster->cluster_cpus);
+
+       if (irq_set_affinity(irq, cpumask_of(cluster->on_cpu))) {
+               dev_err(&pdev->dev,
+                       "Unable to set irq affinity (irq=%d, cpu=%d)\n",
+                       irq, cluster->on_cpu);
+               return -ENODEV;
+       }
+
+       err = devm_request_irq(&pdev->dev, irq, l2_cache__handle_irq,
+                              IRQF_NOBALANCING, "l2-cache-pmu", cluster);
+       if (err) {
+               dev_err(&pdev->dev,
+                       "Unable to request IRQ%d for L2 PMU counters\n", irq);
+               return err;
+       }
+
+       dev_info(&pdev->dev,
+                "Registered L2 cache PMU instance %ld with %d CPUs\n",
+                fw_cluster_id, cpumask_weight(&cluster->cluster_cpus));
+
+       cluster->pmu_lock = __SPIN_LOCK_UNLOCKED(cluster->pmu_lock);
+       cpumask_set_cpu(cluster->on_cpu, &l2cache_pmu->cpumask);
+
+       hml2_pmu__reset(cluster);
+       l2cache_pmu->num_pmus++;
+
+       return 0;
+}
+
+static int l2_cache_pmu_probe(struct platform_device *pdev)
+{
+       int err;
+       struct l2cache_pmu *l2cache_pmu;
+
+       l2cache_pmu =
+               devm_kzalloc(&pdev->dev, sizeof(*l2cache_pmu), GFP_KERNEL);
+       if (!l2cache_pmu)
+               return -ENOMEM;
+
+       platform_set_drvdata(pdev, l2cache_pmu);
+       l2cache_pmu->pmu = (struct pmu) {
+               /* suffix is instance id for future use with multiple sockets */
+               .name           = "l2cache_0",
+               .task_ctx_nr    = perf_invalid_context,
+               .pmu_enable     = l2_cache__pmu_enable,
+               .pmu_disable    = l2_cache__pmu_disable,
+               .event_init     = l2_cache__event_init,
+               .add            = l2_cache__event_add,
+               .del            = l2_cache__event_del,
+               .start          = l2_cache__event_start,
+               .stop           = l2_cache__event_stop,
+               .read           = l2_cache__event_read,
+               .attr_groups    = l2_cache_pmu_attr_grps,
+               .filter_match   = l2_cache_filter_match,
+       };
+
+       l2cache_pmu->num_counters = get_num_counters();
+       l2cache_pmu->pdev = pdev;
+       l2_cycle_ctr_idx = l2cache_pmu->num_counters - 1;
+       l2_counter_present_mask = GENMASK(l2cache_pmu->num_counters - 2, 0) |
+               L2PM_CC_ENABLE;
+
+       cpumask_clear(&l2cache_pmu->cpumask);
+
+       /* Read cluster info and initialize each cluster */
+       err = device_for_each_child(&pdev->dev, l2cache_pmu,
+                                   l2_cache_pmu_probe_cluster);
+       if (err < 0)
+               return err;
+
+       if (l2cache_pmu->num_pmus == 0) {
+               dev_err(&pdev->dev, "No hardware L2 cache PMUs found\n");
+               return -ENODEV;
+       }
+
+       err = perf_pmu_register(&l2cache_pmu->pmu, l2cache_pmu->pmu.name, -1);
+       if (err < 0) {
+               dev_err(&pdev->dev, "Error %d registering L2 cache PMU\n", err);
+               return err;
+       }
+
+       dev_info(&pdev->dev, "Registered L2 cache PMU using %d HW PMUs\n",
+                l2cache_pmu->num_pmus);
+
+       err = cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
+                                              &l2cache_pmu->node);
+
+       return err;
+}
+
+static int l2_cache_pmu_remove(struct platform_device *pdev)
+{
+       struct l2cache_pmu *l2cache_pmu =
+               to_l2cache_pmu(platform_get_drvdata(pdev));
+
+       cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
+                                              &l2cache_pmu->node);
+       perf_pmu_unregister(&l2cache_pmu->pmu);
+       return 0;
+}
+
+static struct platform_driver l2_cache_pmu_driver = {
+       .driver = {
+               .name = "qcom-l2cache-pmu",
+               .owner = THIS_MODULE,
+               .acpi_match_table = ACPI_PTR(l2_cache_pmu_acpi_match),
+       },
+       .probe = l2_cache_pmu_probe,
+       .remove = l2_cache_pmu_remove,
+};
+
+static int __init register_l2_cache_pmu_driver(void)
+{
+       int err;
+
+       err = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
+                                     "AP_PERF_ARM_QCOM_L2_ONLINE",
+                                     l2cache_pmu_online_cpu,
+                                     l2cache_pmu_offline_cpu);
+       if (err)
+               return err;
+
+       return platform_driver_register(&l2_cache_pmu_driver);
+}
+device_initcall(register_l2_cache_pmu_driver);
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 45a4287..f342842 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -113,6 +113,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_ARM_CCI_ONLINE,
        CPUHP_AP_PERF_ARM_CCN_ONLINE,
        CPUHP_AP_PERF_ARM_L2X0_ONLINE,
+       CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
        CPUHP_AP_WORKQUEUE_ONLINE,
        CPUHP_AP_RCUTREE_ONLINE,
        CPUHP_AP_NOTIFY_ONLINE,
-- 
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Inc.
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