drm/rockchip: Don't change hdmi reference clock rate

[drm/drm-misc.git] / drivers / hwtracing / coresight / coresight-etm-perf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright(C) 2015 Linaro Limited. All rights reserved.
 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
 */

#include <linux/bitfield.h>
#include <linux/coresight.h>
#include <linux/coresight-pmu.h>
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/perf_event.h>
#include <linux/percpu-defs.h>
#include <linux/slab.h>
#include <linux/stringhash.h>
#include <linux/types.h>
#include <linux/workqueue.h>

#include "coresight-config.h"
#include "coresight-etm-perf.h"
#include "coresight-priv.h"
#include "coresight-syscfg.h"
#include "coresight-trace-id.h"

static struct pmu etm_pmu;
static bool etm_perf_up;

/*
 * An ETM context for a running event includes the perf aux handle
 * and aux_data. For ETM, the aux_data (etm_event_data), consists of
 * the trace path and the sink configuration. The event data is accessible
 * via perf_get_aux(handle). However, a sink could "end" a perf output
 * handle via the IRQ handler. And if the "sink" encounters a failure
 * to "begin" another session (e.g due to lack of space in the buffer),
 * the handle will be cleared. Thus, the event_data may not be accessible
 * from the handle when we get to the etm_event_stop(), which is required
 * for stopping the trace path. The event_data is guaranteed to stay alive
 * until "free_aux()", which cannot happen as long as the event is active on
 * the ETM. Thus the event_data for the session must be part of the ETM context
 * to make sure we can disable the trace path.
 */
struct etm_ctxt {
        struct perf_output_handle handle;
        struct etm_event_data *event_data;
};

static DEFINE_PER_CPU(struct etm_ctxt, etm_ctxt);
static DEFINE_PER_CPU(struct coresight_device *, csdev_src);

/*
 * The PMU formats were orignally for ETMv3.5/PTM's ETMCR 'config';
 * now take them as general formats and apply on all ETMs.
 */
PMU_FORMAT_ATTR(branch_broadcast, "config:"__stringify(ETM_OPT_BRANCH_BROADCAST));
PMU_FORMAT_ATTR(cycacc,         "config:" __stringify(ETM_OPT_CYCACC));
/* contextid1 enables tracing CONTEXTIDR_EL1 for ETMv4 */
PMU_FORMAT_ATTR(contextid1,     "config:" __stringify(ETM_OPT_CTXTID));
/* contextid2 enables tracing CONTEXTIDR_EL2 for ETMv4 */
PMU_FORMAT_ATTR(contextid2,     "config:" __stringify(ETM_OPT_CTXTID2));
PMU_FORMAT_ATTR(timestamp,      "config:" __stringify(ETM_OPT_TS));
PMU_FORMAT_ATTR(retstack,       "config:" __stringify(ETM_OPT_RETSTK));
/* preset - if sink ID is used as a configuration selector */
PMU_FORMAT_ATTR(preset,         "config:0-3");
/* Sink ID - same for all ETMs */
PMU_FORMAT_ATTR(sinkid,         "config2:0-31");
/* config ID - set if a system configuration is selected */
PMU_FORMAT_ATTR(configid,       "config2:32-63");
PMU_FORMAT_ATTR(cc_threshold,   "config3:0-11");


/*
 * contextid always traces the "PID".  The PID is in CONTEXTIDR_EL1
 * when the kernel is running at EL1; when the kernel is at EL2,
 * the PID is in CONTEXTIDR_EL2.
 */
static ssize_t format_attr_contextid_show(struct device *dev,
                                          struct device_attribute *attr,
                                          char *page)
{
        int pid_fmt = ETM_OPT_CTXTID;

#if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
        pid_fmt = is_kernel_in_hyp_mode() ? ETM_OPT_CTXTID2 : ETM_OPT_CTXTID;
#endif
        return sprintf(page, "config:%d\n", pid_fmt);
}

static struct device_attribute format_attr_contextid =
        __ATTR(contextid, 0444, format_attr_contextid_show, NULL);

static struct attribute *etm_config_formats_attr[] = {
        &format_attr_cycacc.attr,
        &format_attr_contextid.attr,
        &format_attr_contextid1.attr,
        &format_attr_contextid2.attr,
        &format_attr_timestamp.attr,
        &format_attr_retstack.attr,
        &format_attr_sinkid.attr,
        &format_attr_preset.attr,
        &format_attr_configid.attr,
        &format_attr_branch_broadcast.attr,
        &format_attr_cc_threshold.attr,
        NULL,
};

static const struct attribute_group etm_pmu_format_group = {
        .name   = "format",
        .attrs  = etm_config_formats_attr,
};

static struct attribute *etm_config_sinks_attr[] = {
        NULL,
};

static const struct attribute_group etm_pmu_sinks_group = {
        .name   = "sinks",
        .attrs  = etm_config_sinks_attr,
};

static struct attribute *etm_config_events_attr[] = {
        NULL,
};

static const struct attribute_group etm_pmu_events_group = {
        .name   = "events",
        .attrs  = etm_config_events_attr,
};

static const struct attribute_group *etm_pmu_attr_groups[] = {
        &etm_pmu_format_group,
        &etm_pmu_sinks_group,
        &etm_pmu_events_group,
        NULL,
};

static inline struct list_head **
etm_event_cpu_path_ptr(struct etm_event_data *data, int cpu)
{
        return per_cpu_ptr(data->path, cpu);
}

static inline struct list_head *
etm_event_cpu_path(struct etm_event_data *data, int cpu)
{
        return *etm_event_cpu_path_ptr(data, cpu);
}

static void etm_event_read(struct perf_event *event) {}

static int etm_addr_filters_alloc(struct perf_event *event)
{
        struct etm_filters *filters;
        int node = event->cpu == -1 ? -1 : cpu_to_node(event->cpu);

        filters = kzalloc_node(sizeof(struct etm_filters), GFP_KERNEL, node);
        if (!filters)
                return -ENOMEM;

        if (event->parent)
                memcpy(filters, event->parent->hw.addr_filters,
                       sizeof(*filters));

        event->hw.addr_filters = filters;

        return 0;
}

static void etm_event_destroy(struct perf_event *event)
{
        kfree(event->hw.addr_filters);
        event->hw.addr_filters = NULL;
}

static int etm_event_init(struct perf_event *event)
{
        int ret = 0;

        if (event->attr.type != etm_pmu.type) {
                ret = -ENOENT;
                goto out;
        }

        ret = etm_addr_filters_alloc(event);
        if (ret)
                goto out;

        event->destroy = etm_event_destroy;
out:
        return ret;
}

static void free_sink_buffer(struct etm_event_data *event_data)
{
        int cpu;
        cpumask_t *mask = &event_data->mask;
        struct coresight_device *sink;

        if (!event_data->snk_config)
                return;

        if (WARN_ON(cpumask_empty(mask)))
                return;

        cpu = cpumask_first(mask);
        sink = coresight_get_sink(etm_event_cpu_path(event_data, cpu));
        sink_ops(sink)->free_buffer(event_data->snk_config);
}

static void free_event_data(struct work_struct *work)
{
        int cpu;
        cpumask_t *mask;
        struct etm_event_data *event_data;

        event_data = container_of(work, struct etm_event_data, work);
        mask = &event_data->mask;

        /* Free the sink buffers, if there are any */
        free_sink_buffer(event_data);

        /* clear any configuration we were using */
        if (event_data->cfg_hash)
                cscfg_deactivate_config(event_data->cfg_hash);

        for_each_cpu(cpu, mask) {
                struct list_head **ppath;

                ppath = etm_event_cpu_path_ptr(event_data, cpu);
                if (!(IS_ERR_OR_NULL(*ppath))) {
                        struct coresight_device *sink = coresight_get_sink(*ppath);

                        /*
                         * Mark perf event as done for trace id allocator, but don't call
                         * coresight_trace_id_put_cpu_id_map() on individual IDs. Perf sessions
                         * never free trace IDs to ensure that the ID associated with a CPU
                         * cannot change during their and other's concurrent sessions. Instead,
                         * a refcount is used so that the last event to call
                         * coresight_trace_id_perf_stop() frees all IDs.
                         */
                        coresight_trace_id_perf_stop(&sink->perf_sink_id_map);

                        coresight_release_path(*ppath);
                }
                *ppath = NULL;
        }

        free_percpu(event_data->path);
        kfree(event_data);
}

static void *alloc_event_data(int cpu)
{
        cpumask_t *mask;
        struct etm_event_data *event_data;

        /* First get memory for the session's data */
        event_data = kzalloc(sizeof(struct etm_event_data), GFP_KERNEL);
        if (!event_data)
                return NULL;


        mask = &event_data->mask;
        if (cpu != -1)
                cpumask_set_cpu(cpu, mask);
        else
                cpumask_copy(mask, cpu_present_mask);

        /*
         * Each CPU has a single path between source and destination.  As such
         * allocate an array using CPU numbers as indexes.  That way a path
         * for any CPU can easily be accessed at any given time.  We proceed
         * the same way for sessions involving a single CPU.  The cost of
         * unused memory when dealing with single CPU trace scenarios is small
         * compared to the cost of searching through an optimized array.
         */
        event_data->path = alloc_percpu(struct list_head *);

        if (!event_data->path) {
                kfree(event_data);
                return NULL;
        }

        return event_data;
}

static void etm_free_aux(void *data)
{
        struct etm_event_data *event_data = data;

        schedule_work(&event_data->work);
}

/*
 * Check if two given sinks are compatible with each other,
 * so that they can use the same sink buffers, when an event
 * moves around.
 */
static bool sinks_compatible(struct coresight_device *a,
                             struct coresight_device *b)
{
        if (!a || !b)
                return false;
        /*
         * If the sinks are of the same subtype and driven
         * by the same driver, we can use the same buffer
         * on these sinks.
         */
        return (a->subtype.sink_subtype == b->subtype.sink_subtype) &&
               (sink_ops(a) == sink_ops(b));
}

static void *etm_setup_aux(struct perf_event *event, void **pages,
                           int nr_pages, bool overwrite)
{
        u32 id, cfg_hash;
        int cpu = event->cpu;
        int trace_id;
        cpumask_t *mask;
        struct coresight_device *sink = NULL;
        struct coresight_device *user_sink = NULL, *last_sink = NULL;
        struct etm_event_data *event_data = NULL;

        event_data = alloc_event_data(cpu);
        if (!event_data)
                return NULL;
        INIT_WORK(&event_data->work, free_event_data);

        /* First get the selected sink from user space. */
        if (event->attr.config2 & GENMASK_ULL(31, 0)) {
                id = (u32)event->attr.config2;
                sink = user_sink = coresight_get_sink_by_id(id);
        }

        /* check if user wants a coresight configuration selected */
        cfg_hash = (u32)((event->attr.config2 & GENMASK_ULL(63, 32)) >> 32);
        if (cfg_hash) {
                if (cscfg_activate_config(cfg_hash))
                        goto err;
                event_data->cfg_hash = cfg_hash;
        }

        mask = &event_data->mask;

        /*
         * Setup the path for each CPU in a trace session. We try to build
         * trace path for each CPU in the mask. If we don't find an ETM
         * for the CPU or fail to build a path, we clear the CPU from the
         * mask and continue with the rest. If ever we try to trace on those
         * CPUs, we can handle it and fail the session.
         */
        for_each_cpu(cpu, mask) {
                struct list_head *path;
                struct coresight_device *csdev;

                csdev = per_cpu(csdev_src, cpu);
                /*
                 * If there is no ETM associated with this CPU clear it from
                 * the mask and continue with the rest. If ever we try to trace
                 * on this CPU, we handle it accordingly.
                 */
                if (!csdev) {
                        cpumask_clear_cpu(cpu, mask);
                        continue;
                }

                /*
                 * No sink provided - look for a default sink for all the ETMs,
                 * where this event can be scheduled.
                 * We allocate the sink specific buffers only once for this
                 * event. If the ETMs have different default sink devices, we
                 * can only use a single "type" of sink as the event can carry
                 * only one sink specific buffer. Thus we have to make sure
                 * that the sinks are of the same type and driven by the same
                 * driver, as the one we allocate the buffer for. As such
                 * we choose the first sink and check if the remaining ETMs
                 * have a compatible default sink. We don't trace on a CPU
                 * if the sink is not compatible.
                 */
                if (!user_sink) {
                        /* Find the default sink for this ETM */
                        sink = coresight_find_default_sink(csdev);
                        if (!sink) {
                                cpumask_clear_cpu(cpu, mask);
                                continue;
                        }

                        /* Check if this sink compatible with the last sink */
                        if (last_sink && !sinks_compatible(last_sink, sink)) {
                                cpumask_clear_cpu(cpu, mask);
                                continue;
                        }
                        last_sink = sink;
                }

                /*
                 * Building a path doesn't enable it, it simply builds a
                 * list of devices from source to sink that can be
                 * referenced later when the path is actually needed.
                 */
                path = coresight_build_path(csdev, sink);
                if (IS_ERR(path)) {
                        cpumask_clear_cpu(cpu, mask);
                        continue;
                }

                /* ensure we can allocate a trace ID for this CPU */
                trace_id = coresight_trace_id_get_cpu_id_map(cpu, &sink->perf_sink_id_map);
                if (!IS_VALID_CS_TRACE_ID(trace_id)) {
                        cpumask_clear_cpu(cpu, mask);
                        coresight_release_path(path);
                        continue;
                }

                coresight_trace_id_perf_start(&sink->perf_sink_id_map);
                *etm_event_cpu_path_ptr(event_data, cpu) = path;
        }

        /* no sink found for any CPU - cannot trace */
        if (!sink)
                goto err;

        /* If we don't have any CPUs ready for tracing, abort */
        cpu = cpumask_first(mask);
        if (cpu >= nr_cpu_ids)
                goto err;

        if (!sink_ops(sink)->alloc_buffer || !sink_ops(sink)->free_buffer)
                goto err;

        /*
         * Allocate the sink buffer for this session. All the sinks
         * where this event can be scheduled are ensured to be of the
         * same type. Thus the same sink configuration is used by the
         * sinks.
         */
        event_data->snk_config =
                        sink_ops(sink)->alloc_buffer(sink, event, pages,
                                                     nr_pages, overwrite);
        if (!event_data->snk_config)
                goto err;

out:
        return event_data;

err:
        etm_free_aux(event_data);
        event_data = NULL;
        goto out;
}

static void etm_event_start(struct perf_event *event, int flags)
{
        int cpu = smp_processor_id();
        struct etm_event_data *event_data;
        struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt);
        struct perf_output_handle *handle = &ctxt->handle;
        struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
        struct list_head *path;
        u64 hw_id;
        u8 trace_id;

        if (!csdev)
                goto fail;

        /* Have we messed up our tracking ? */
        if (WARN_ON(ctxt->event_data))
                goto fail;

        /*
         * Deal with the ring buffer API and get a handle on the
         * session's information.
         */
        event_data = perf_aux_output_begin(handle, event);
        if (!event_data)
                goto fail;

        /*
         * Check if this ETM is allowed to trace, as decided
         * at etm_setup_aux(). This could be due to an unreachable
         * sink from this ETM. We can't do much in this case if
         * the sink was specified or hinted to the driver. For
         * now, simply don't record anything on this ETM.
         *
         * As such we pretend that everything is fine, and let
         * it continue without actually tracing. The event could
         * continue tracing when it moves to a CPU where it is
         * reachable to a sink.
         */
        if (!cpumask_test_cpu(cpu, &event_data->mask))
                goto out;

        path = etm_event_cpu_path(event_data, cpu);
        /* We need a sink, no need to continue without one */
        sink = coresight_get_sink(path);
        if (WARN_ON_ONCE(!sink))
                goto fail_end_stop;

        /* Nothing will happen without a path */
        if (coresight_enable_path(path, CS_MODE_PERF, handle))
                goto fail_end_stop;

        /* Finally enable the tracer */
        if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF,
                                      &sink->perf_sink_id_map))
                goto fail_disable_path;

        /*
         * output cpu / trace ID in perf record, once for the lifetime
         * of the event.
         */
        if (!cpumask_test_cpu(cpu, &event_data->aux_hwid_done)) {
                cpumask_set_cpu(cpu, &event_data->aux_hwid_done);

                trace_id = coresight_trace_id_read_cpu_id_map(cpu, &sink->perf_sink_id_map);

                hw_id = FIELD_PREP(CS_AUX_HW_ID_MAJOR_VERSION_MASK,
                                CS_AUX_HW_ID_MAJOR_VERSION);
                hw_id |= FIELD_PREP(CS_AUX_HW_ID_MINOR_VERSION_MASK,
                                CS_AUX_HW_ID_MINOR_VERSION);
                hw_id |= FIELD_PREP(CS_AUX_HW_ID_TRACE_ID_MASK, trace_id);
                hw_id |= FIELD_PREP(CS_AUX_HW_ID_SINK_ID_MASK, coresight_get_sink_id(sink));

                perf_report_aux_output_id(event, hw_id);
        }

out:
        /* Tell the perf core the event is alive */
        event->hw.state = 0;
        /* Save the event_data for this ETM */
        ctxt->event_data = event_data;
        return;

fail_disable_path:
        coresight_disable_path(path);
fail_end_stop:
        /*
         * Check if the handle is still associated with the event,
         * to handle cases where if the sink failed to start the
         * trace and TRUNCATED the handle already.
         */
        if (READ_ONCE(handle->event)) {
                perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
                perf_aux_output_end(handle, 0);
        }
fail:
        event->hw.state = PERF_HES_STOPPED;
        return;
}

static void etm_event_stop(struct perf_event *event, int mode)
{
        int cpu = smp_processor_id();
        unsigned long size;
        struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
        struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt);
        struct perf_output_handle *handle = &ctxt->handle;
        struct etm_event_data *event_data;
        struct list_head *path;

        /*
         * If we still have access to the event_data via handle,
         * confirm that we haven't messed up the tracking.
         */
        if (handle->event &&
            WARN_ON(perf_get_aux(handle) != ctxt->event_data))
                return;

        event_data = ctxt->event_data;
        /* Clear the event_data as this ETM is stopping the trace. */
        ctxt->event_data = NULL;

        if (event->hw.state == PERF_HES_STOPPED)
                return;

        /* We must have a valid event_data for a running event */
        if (WARN_ON(!event_data))
                return;

        /*
         * Check if this ETM was allowed to trace, as decided at
         * etm_setup_aux(). If it wasn't allowed to trace, then
         * nothing needs to be torn down other than outputting a
         * zero sized record.
         */
        if (handle->event && (mode & PERF_EF_UPDATE) &&
            !cpumask_test_cpu(cpu, &event_data->mask)) {
                event->hw.state = PERF_HES_STOPPED;
                perf_aux_output_end(handle, 0);
                return;
        }

        if (!csdev)
                return;

        path = etm_event_cpu_path(event_data, cpu);
        if (!path)
                return;

        sink = coresight_get_sink(path);
        if (!sink)
                return;

        /* stop tracer */
        coresight_disable_source(csdev, event);

        /* tell the core */
        event->hw.state = PERF_HES_STOPPED;

        /*
         * If the handle is not bound to an event anymore
         * (e.g, the sink driver was unable to restart the
         * handle due to lack of buffer space), we don't
         * have to do anything here.
         */
        if (handle->event && (mode & PERF_EF_UPDATE)) {
                if (WARN_ON_ONCE(handle->event != event))
                        return;

                /* update trace information */
                if (!sink_ops(sink)->update_buffer)
                        return;

                size = sink_ops(sink)->update_buffer(sink, handle,
                                              event_data->snk_config);
                /*
                 * Make sure the handle is still valid as the
                 * sink could have closed it from an IRQ.
                 * The sink driver must handle the race with
                 * update_buffer() and IRQ. Thus either we
                 * should get a valid handle and valid size
                 * (which may be 0).
                 *
                 * But we should never get a non-zero size with
                 * an invalid handle.
                 */
                if (READ_ONCE(handle->event))
                        perf_aux_output_end(handle, size);
                else
                        WARN_ON(size);
        }

        /* Disabling the path make its elements available to other sessions */
        coresight_disable_path(path);
}

static int etm_event_add(struct perf_event *event, int mode)
{
        int ret = 0;
        struct hw_perf_event *hwc = &event->hw;

        if (mode & PERF_EF_START) {
                etm_event_start(event, 0);
                if (hwc->state & PERF_HES_STOPPED)
                        ret = -EINVAL;
        } else {
                hwc->state = PERF_HES_STOPPED;
        }

        return ret;
}

static void etm_event_del(struct perf_event *event, int mode)
{
        etm_event_stop(event, PERF_EF_UPDATE);
}

static int etm_addr_filters_validate(struct list_head *filters)
{
        bool range = false, address = false;
        int index = 0;
        struct perf_addr_filter *filter;

        list_for_each_entry(filter, filters, entry) {
                /*
                 * No need to go further if there's no more
                 * room for filters.
                 */
                if (++index > ETM_ADDR_CMP_MAX)
                        return -EOPNOTSUPP;

                /* filter::size==0 means single address trigger */
                if (filter->size) {
                        /*
                         * The existing code relies on START/STOP filters
                         * being address filters.
                         */
                        if (filter->action == PERF_ADDR_FILTER_ACTION_START ||
                            filter->action == PERF_ADDR_FILTER_ACTION_STOP)
                                return -EOPNOTSUPP;

                        range = true;
                } else
                        address = true;

                /*
                 * At this time we don't allow range and start/stop filtering
                 * to cohabitate, they have to be mutually exclusive.
                 */
                if (range && address)
                        return -EOPNOTSUPP;
        }

        return 0;
}

static void etm_addr_filters_sync(struct perf_event *event)
{
        struct perf_addr_filters_head *head = perf_event_addr_filters(event);
        unsigned long start, stop;
        struct perf_addr_filter_range *fr = event->addr_filter_ranges;
        struct etm_filters *filters = event->hw.addr_filters;
        struct etm_filter *etm_filter;
        struct perf_addr_filter *filter;
        int i = 0;

        list_for_each_entry(filter, &head->list, entry) {
                start = fr[i].start;
                stop = start + fr[i].size;
                etm_filter = &filters->etm_filter[i];

                switch (filter->action) {
                case PERF_ADDR_FILTER_ACTION_FILTER:
                        etm_filter->start_addr = start;
                        etm_filter->stop_addr = stop;
                        etm_filter->type = ETM_ADDR_TYPE_RANGE;
                        break;
                case PERF_ADDR_FILTER_ACTION_START:
                        etm_filter->start_addr = start;
                        etm_filter->type = ETM_ADDR_TYPE_START;
                        break;
                case PERF_ADDR_FILTER_ACTION_STOP:
                        etm_filter->stop_addr = stop;
                        etm_filter->type = ETM_ADDR_TYPE_STOP;
                        break;
                }
                i++;
        }

        filters->nr_filters = i;
}

int etm_perf_symlink(struct coresight_device *csdev, bool link)
{
        char entry[sizeof("cpu9999999")];
        int ret = 0, cpu = source_ops(csdev)->cpu_id(csdev);
        struct device *pmu_dev = etm_pmu.dev;
        struct device *cs_dev = &csdev->dev;

        sprintf(entry, "cpu%d", cpu);

        if (!etm_perf_up)
                return -EPROBE_DEFER;

        if (link) {
                ret = sysfs_create_link(&pmu_dev->kobj, &cs_dev->kobj, entry);
                if (ret)
                        return ret;
                per_cpu(csdev_src, cpu) = csdev;
        } else {
                sysfs_remove_link(&pmu_dev->kobj, entry);
                per_cpu(csdev_src, cpu) = NULL;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(etm_perf_symlink);

static ssize_t etm_perf_sink_name_show(struct device *dev,
                                       struct device_attribute *dattr,
                                       char *buf)
{
        struct dev_ext_attribute *ea;

        ea = container_of(dattr, struct dev_ext_attribute, attr);
        return scnprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)(ea->var));
}

static struct dev_ext_attribute *
etm_perf_add_symlink_group(struct device *dev, const char *name, const char *group_name)
{
        struct dev_ext_attribute *ea;
        unsigned long hash;
        int ret;
        struct device *pmu_dev = etm_pmu.dev;

        if (!etm_perf_up)
                return ERR_PTR(-EPROBE_DEFER);

        ea = devm_kzalloc(dev, sizeof(*ea), GFP_KERNEL);
        if (!ea)
                return ERR_PTR(-ENOMEM);

        /*
         * If this function is called adding a sink then the hash is used for
         * sink selection - see function coresight_get_sink_by_id().
         * If adding a configuration then the hash is used for selection in
         * cscfg_activate_config()
         */
        hash = hashlen_hash(hashlen_string(NULL, name));

        sysfs_attr_init(&ea->attr.attr);
        ea->attr.attr.name = devm_kstrdup(dev, name, GFP_KERNEL);
        if (!ea->attr.attr.name)
                return ERR_PTR(-ENOMEM);

        ea->attr.attr.mode = 0444;
        ea->var = (unsigned long *)hash;

        ret = sysfs_add_file_to_group(&pmu_dev->kobj,
                                      &ea->attr.attr, group_name);

        return ret ? ERR_PTR(ret) : ea;
}

int etm_perf_add_symlink_sink(struct coresight_device *csdev)
{
        const char *name;
        struct device *dev = &csdev->dev;
        int err = 0;

        if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
            csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
                return -EINVAL;

        if (csdev->ea != NULL)
                return -EINVAL;

        name = dev_name(dev);
        csdev->ea = etm_perf_add_symlink_group(dev, name, "sinks");
        if (IS_ERR(csdev->ea)) {
                err = PTR_ERR(csdev->ea);
                csdev->ea = NULL;
        } else
                csdev->ea->attr.show = etm_perf_sink_name_show;

        return err;
}

static void etm_perf_del_symlink_group(struct dev_ext_attribute *ea, const char *group_name)
{
        struct device *pmu_dev = etm_pmu.dev;

        sysfs_remove_file_from_group(&pmu_dev->kobj,
                                     &ea->attr.attr, group_name);
}

void etm_perf_del_symlink_sink(struct coresight_device *csdev)
{
        if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
            csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
                return;

        if (!csdev->ea)
                return;

        etm_perf_del_symlink_group(csdev->ea, "sinks");
        csdev->ea = NULL;
}

static ssize_t etm_perf_cscfg_event_show(struct device *dev,
                                         struct device_attribute *dattr,
                                         char *buf)
{
        struct dev_ext_attribute *ea;

        ea = container_of(dattr, struct dev_ext_attribute, attr);
        return scnprintf(buf, PAGE_SIZE, "configid=0x%lx\n", (unsigned long)(ea->var));
}

int etm_perf_add_symlink_cscfg(struct device *dev, struct cscfg_config_desc *config_desc)
{
        int err = 0;

        if (config_desc->event_ea != NULL)
                return 0;

        config_desc->event_ea = etm_perf_add_symlink_group(dev, config_desc->name, "events");

        /* set the show function to the custom cscfg event */
        if (!IS_ERR(config_desc->event_ea))
                config_desc->event_ea->attr.show = etm_perf_cscfg_event_show;
        else {
                err = PTR_ERR(config_desc->event_ea);
                config_desc->event_ea = NULL;
        }

        return err;
}

void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *config_desc)
{
        if (!config_desc->event_ea)
                return;

        etm_perf_del_symlink_group(config_desc->event_ea, "events");
        config_desc->event_ea = NULL;
}

int __init etm_perf_init(void)
{
        int ret;

        etm_pmu.capabilities            = (PERF_PMU_CAP_EXCLUSIVE |
                                           PERF_PMU_CAP_ITRACE);

        etm_pmu.attr_groups             = etm_pmu_attr_groups;
        etm_pmu.task_ctx_nr             = perf_sw_context;
        etm_pmu.read                    = etm_event_read;
        etm_pmu.event_init              = etm_event_init;
        etm_pmu.setup_aux               = etm_setup_aux;
        etm_pmu.free_aux                = etm_free_aux;
        etm_pmu.start                   = etm_event_start;
        etm_pmu.stop                    = etm_event_stop;
        etm_pmu.add                     = etm_event_add;
        etm_pmu.del                     = etm_event_del;
        etm_pmu.addr_filters_sync       = etm_addr_filters_sync;
        etm_pmu.addr_filters_validate   = etm_addr_filters_validate;
        etm_pmu.nr_addr_filters         = ETM_ADDR_CMP_MAX;
        etm_pmu.module                  = THIS_MODULE;

        ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
        if (ret == 0)
                etm_perf_up = true;

        return ret;
}

void etm_perf_exit(void)
{
        perf_pmu_unregister(&etm_pmu);
}