ARC: Add perf support for ARC700 cores

This adds basic perf support for ARC700 cores. Most PERF_COUNT_HW* events
are supported now.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 323 insertions, 0 deletions

diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index c242ef07ba70..8004b4fa6461 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_KPROBES)      		+= kprobes.o
 obj-$(CONFIG_ARC_MISALIGN_ACCESS)       += unaligned.o
 obj-$(CONFIG_KGDB)                      += kgdb.o
 obj-$(CONFIG_ARC_METAWARE_HLINK)        += arc_hostlink.o
+obj-$(CONFIG_PERF_EVENTS)               += perf_event.o
 
 obj-$(CONFIG_ARC_FPU_SAVE_RESTORE)      += fpu.o
 CFLAGS_fpu.o   += -mdpfp
diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
new file mode 100644
index 000000000000..759e5f3e9029
--- /dev/null
+++ b/arch/arc/kernel/perf_event.c
@@ -0,0 +1,322 @@
+/*
+ * Linux performance counter support for ARC700 series
+ *
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This code is inspired by the perf support of various other architectures.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/perf_event.h>
+#include <linux/platform_device.h>
+#include <asm/arcregs.h>
+
+struct arc_pmu {
+        struct pmu      pmu;
+        int             counter_size;   /* in bits */
+        int             n_counters;
+        unsigned long   used_mask[BITS_TO_LONGS(ARC_PMU_MAX_HWEVENTS)];
+        int             ev_hw_idx[PERF_COUNT_ARC_HW_MAX];
+};
+
+/* read counter #idx; note that counter# != event# on ARC! */
+static uint64_t arc_pmu_read_counter(int idx)
+{
+        uint32_t tmp;
+        uint64_t result;
+
+        /*
+         * ARC supports making 'snapshots' of the counters, so we don't
+         * need to care about counters wrapping to 0 underneath our feet
+         */
+        write_aux_reg(ARC_REG_PCT_INDEX, idx);
+        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
+        write_aux_reg(ARC_REG_PCT_CONTROL, tmp | ARC_REG_PCT_CONTROL_SN);
+        result = (uint64_t) (read_aux_reg(ARC_REG_PCT_SNAPH)) << 32;
+        result |= read_aux_reg(ARC_REG_PCT_SNAPL);
+
+        return result;
+}
+
+static void arc_perf_event_update(struct perf_event *event,
+                                  struct hw_perf_event *hwc, int idx)
+{
+        struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
+        uint64_t prev_raw_count, new_raw_count;
+        int64_t delta;
+
+        do {
+                prev_raw_count = local64_read(&hwc->prev_count);
+                new_raw_count = arc_pmu_read_counter(idx);
+        } while (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+                                 new_raw_count) != prev_raw_count);
+
+        delta = (new_raw_count - prev_raw_count) &
+                ((1ULL << arc_pmu->counter_size) - 1ULL);
+
+        local64_add(delta, &event->count);
+        local64_sub(delta, &hwc->period_left);
+}
+
+static void arc_pmu_read(struct perf_event *event)
+{
+        arc_perf_event_update(event, &event->hw, event->hw.idx);
+}
+
+static int arc_pmu_cache_event(u64 config)
+{
+        unsigned int cache_type, cache_op, cache_result;
+        int ret;
+
+        cache_type      = (config >>  0) & 0xff;
+        cache_op        = (config >>  8) & 0xff;
+        cache_result    = (config >> 16) & 0xff;
+        if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+                return -EINVAL;
+        if (cache_type >= PERF_COUNT_HW_CACHE_OP_MAX)
+                return -EINVAL;
+        if (cache_type >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+                return -EINVAL;
+
+        ret = arc_pmu_cache_map[cache_type][cache_op][cache_result];
+
+        if (ret == CACHE_OP_UNSUPPORTED)
+                return -ENOENT;
+
+        return ret;
+}
+
+/* initializes hw_perf_event structure if event is supported */
+static int arc_pmu_event_init(struct perf_event *event)
+{
+        struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
+        struct hw_perf_event *hwc = &event->hw;
+        int ret;
+
+        switch (event->attr.type) {
+        case PERF_TYPE_HARDWARE:
+                if (event->attr.config >= PERF_COUNT_HW_MAX)
+                        return -ENOENT;
+                if (arc_pmu->ev_hw_idx[event->attr.config] < 0)
+                        return -ENOENT;
+                hwc->config = arc_pmu->ev_hw_idx[event->attr.config];
+                pr_debug("initializing event %d with cfg %d\n",
+                         (int) event->attr.config, (int) hwc->config);
+                return 0;
+        case PERF_TYPE_HW_CACHE:
+                ret = arc_pmu_cache_event(event->attr.config);
+                if (ret < 0)
+                        return ret;
+                hwc->config = arc_pmu->ev_hw_idx[ret];
+                return 0;
+        default:
+                return -ENOENT;
+        }
+}
+
+/* starts all counters */
+static void arc_pmu_enable(struct pmu *pmu)
+{
+        uint32_t tmp;
+        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
+        write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x1);
+}
+
+/* stops all counters */
+static void arc_pmu_disable(struct pmu *pmu)
+{
+        uint32_t tmp;
+        tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
+        write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x0);
+}
+
+/*
+ * Assigns hardware counter to hardware condition.
+ * Note that there is no separate start/stop mechanism;
+ * stopping is achieved by assigning the 'never' condition
+ */
+static void arc_pmu_start(struct perf_event *event, int flags)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        int idx = hwc->idx;
+
+        if (WARN_ON_ONCE(idx == -1))
+                return;
+
+        if (flags & PERF_EF_RELOAD)
+                WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+
+        event->hw.state = 0;
+
+        /* enable ARC pmu here */
+        write_aux_reg(ARC_REG_PCT_INDEX, idx);
+        write_aux_reg(ARC_REG_PCT_CONFIG, hwc->config);
+}
+
+static void arc_pmu_stop(struct perf_event *event, int flags)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        int idx = hwc->idx;
+
+        if (!(event->hw.state & PERF_HES_STOPPED)) {
+                /* stop ARC pmu here */
+                write_aux_reg(ARC_REG_PCT_INDEX, idx);
+
+                /* condition code #0 is always "never" */
+                write_aux_reg(ARC_REG_PCT_CONFIG, 0);
+
+                event->hw.state |= PERF_HES_STOPPED;
+        }
+
+        if ((flags & PERF_EF_UPDATE) &&
+            !(event->hw.state & PERF_HES_UPTODATE)) {
+                arc_perf_event_update(event, &event->hw, idx);
+                event->hw.state |= PERF_HES_UPTODATE;
+        }
+}
+
+static void arc_pmu_del(struct perf_event *event, int flags)
+{
+        struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
+
+        arc_pmu_stop(event, PERF_EF_UPDATE);
+        __clear_bit(event->hw.idx, arc_pmu->used_mask);
+
+        perf_event_update_userpage(event);
+}
+
+/* allocate hardware counter and optionally start counting */
+static int arc_pmu_add(struct perf_event *event, int flags)
+{
+        struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
+        struct hw_perf_event *hwc = &event->hw;
+        int idx = hwc->idx;
+
+        if (__test_and_set_bit(idx, arc_pmu->used_mask)) {
+                idx = find_first_zero_bit(arc_pmu->used_mask,
+                                          arc_pmu->n_counters);
+                if (idx == arc_pmu->n_counters)
+                        return -EAGAIN;
+
+                __set_bit(idx, arc_pmu->used_mask);
+                hwc->idx = idx;
+        }
+
+        write_aux_reg(ARC_REG_PCT_INDEX, idx);
+        write_aux_reg(ARC_REG_PCT_CONFIG, 0);
+        write_aux_reg(ARC_REG_PCT_COUNTL, 0);
+        write_aux_reg(ARC_REG_PCT_COUNTH, 0);
+        local64_set(&hwc->prev_count, 0);
+
+        hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+        if (flags & PERF_EF_START)
+                arc_pmu_start(event, PERF_EF_RELOAD);
+
+        perf_event_update_userpage(event);
+
+        return 0;
+}
+
+static int arc_pmu_device_probe(struct platform_device *pdev)
+{
+        struct arc_pmu *arc_pmu;
+        struct arc_reg_pct_build pct_bcr;
+        struct arc_reg_cc_build cc_bcr;
+        int i, j, ret;
+
+        union cc_name {
+                struct {
+                        uint32_t word0, word1;
+                        char sentinel;
+                } indiv;
+                char str[9];
+        } cc_name;
+
+
+        READ_BCR(ARC_REG_PCT_BUILD, pct_bcr);
+        if (!pct_bcr.v) {
+                pr_err("This core does not have performance counters!\n");
+                return -ENODEV;
+        }
+
+        arc_pmu = devm_kzalloc(&pdev->dev, sizeof(struct arc_pmu),
+                               GFP_KERNEL);
+        if (!arc_pmu)
+                return -ENOMEM;
+
+        arc_pmu->n_counters = pct_bcr.c;
+        BUG_ON(arc_pmu->n_counters > ARC_PMU_MAX_HWEVENTS);
+
+        arc_pmu->counter_size = 32 + (pct_bcr.s << 4);
+        pr_info("ARC PMU found with %d counters of size %d bits\n",
+                arc_pmu->n_counters, arc_pmu->counter_size);
+
+        READ_BCR(ARC_REG_CC_BUILD, cc_bcr);
+
+        if (!cc_bcr.v)
+                pr_err("Strange! Performance counters exist, but no countable conditions?\n");
+
+        pr_info("ARC PMU has %d countable conditions\n", cc_bcr.c);
+
+        cc_name.str[8] = 0;
+        for (i = 0; i < PERF_COUNT_HW_MAX; i++)
+                arc_pmu->ev_hw_idx[i] = -1;
+
+        for (j = 0; j < cc_bcr.c; j++) {
+                write_aux_reg(ARC_REG_CC_INDEX, j);
+                cc_name.indiv.word0 = read_aux_reg(ARC_REG_CC_NAME0);
+                cc_name.indiv.word1 = read_aux_reg(ARC_REG_CC_NAME1);
+                for (i = 0; i < ARRAY_SIZE(arc_pmu_ev_hw_map); i++) {
+                        if (arc_pmu_ev_hw_map[i] &&
+                            !strcmp(arc_pmu_ev_hw_map[i], cc_name.str) &&
+                            strlen(arc_pmu_ev_hw_map[i])) {
+                                pr_debug("mapping %d to idx %d with name %s\n",
+                                         i, j, cc_name.str);
+                                arc_pmu->ev_hw_idx[i] = j;
+                        }
+                }
+        }
+
+        arc_pmu->pmu = (struct pmu) {
+                .pmu_enable     = arc_pmu_enable,
+                .pmu_disable    = arc_pmu_disable,
+                .event_init     = arc_pmu_event_init,
+                .add            = arc_pmu_add,
+                .del            = arc_pmu_del,
+                .start          = arc_pmu_start,
+                .stop           = arc_pmu_stop,
+                .read           = arc_pmu_read,
+        };
+
+        ret = perf_pmu_register(&arc_pmu->pmu, pdev->name, PERF_TYPE_RAW);
+
+        return ret;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id arc_pmu_match[] = {
+        { .compatible = "snps,arc700-pmu" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, arc_pmu_match);
+#endif
+
+static struct platform_driver arc_pmu_driver = {
+        .driver = {
+                .name           = "arc700-pmu",
+                .of_match_table = of_match_ptr(arc_pmu_match),
+        },
+        .probe          = arc_pmu_device_probe,
+};
+
+module_platform_driver(arc_pmu_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mischa Jonker <mjonker@synopsys.com>");
+MODULE_DESCRIPTION("ARC PMU driver");