Re: [PATCH v2 05/13] coresight: etm3x: Update ETM3 driver to use Trace ID API

On 04/07/2022 09:11, Mike Leach wrote:

Use the TraceID API to allocate ETM trace IDs dynamically.

As with the etm4x we allocate on enable / disable for perf, allocate on enable / reset for sysfs.

Additionally we allocate on sysfs file read as both perf and sysfs can read the ID before enabling the hardware.

Remove sysfs option to write trace ID - which is inconsistent with both the dynamic allocation method and the fixed allocation method previously used.

Signed-off-by: Mike Leach mike.leach@linaro.org

drivers/hwtracing/coresight/coresight-etm.h | 2 + .../coresight/coresight-etm3x-core.c | 68 +++++++++++++++++-- .../coresight/coresight-etm3x-sysfs.c | 28 +++----- 3 files changed, 71 insertions(+), 27 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h index f3ab96eaf44e..3667428d38b6 100644 --- a/drivers/hwtracing/coresight/coresight-etm.h +++ b/drivers/hwtracing/coresight/coresight-etm.h @@ -287,4 +287,6 @@ int etm_get_trace_id(struct etm_drvdata *drvdata); void etm_set_default(struct etm_config *config); void etm_config_trace_mode(struct etm_config *config); struct etm_config *get_etm_config(struct etm_drvdata *drvdata); +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata); +void etm_release_trace_id(struct etm_drvdata *drvdata); #endif diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c index d0ab9933472b..273f37be322b 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c @@ -32,6 +32,7 @@ #include "coresight-etm.h" #include "coresight-etm-perf.h" +#include "coresight-trace-id.h" /*

• Not really modular but using module_param is the easiest way to

@@ -490,18 +491,61 @@ static int etm_trace_id(struct coresight_device *csdev) return etm_get_trace_id(drvdata); } +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata) +{

• int trace_id;
• /*

• * This will allocate a trace ID to the cpu,
  

• * or return the one currently allocated.
  

• */
  

• spin_lock(&drvdata->spinlock);
• trace_id = drvdata->traceid;
• if (!trace_id) {

• trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu);
  

• if (trace_id > 0)
  

• 	drvdata->traceid = (u8)trace_id;
  

• }
• spin_unlock(&drvdata->spinlock);
• if (trace_id <= 0)

• pr_err("Failed to allocate trace ID for %s on CPU%d\n",
  

•        dev_name(&drvdata->csdev->dev), drvdata->cpu);
  

dev_err(&drvdata->csdev->dev, ....)

• return trace_id;

+}

+void etm_release_trace_id(struct etm_drvdata *drvdata) +{

• spin_lock(&drvdata->spinlock);
• coresight_trace_id_put_cpu_id(drvdata->cpu);
• drvdata->traceid = 0;
• spin_unlock(&drvdata->spinlock);

+}

• static int etm_enable_perf(struct coresight_device *csdev, struct perf_event *event) { struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
• int ret;

if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id())) return -EINVAL; /* Configure the tracer based on the session's specifics */ etm_parse_event_config(drvdata, event);

• /* allocate a trace ID */
• ret = etm_read_alloc_trace_id(drvdata);
• if (ret < 0)

• return ret;
  

• /* And enable it */

• return etm_enable_hw(drvdata);

• ret = etm_enable_hw(drvdata);
• if (ret)

• etm_release_trace_id(drvdata);
  

• return ret; }

static int etm_enable_sysfs(struct coresight_device *csdev) @@ -510,6 +554,11 @@ static int etm_enable_sysfs(struct coresight_device *csdev) struct etm_enable_arg arg = { }; int ret;

• /* allocate a trace ID */
• ret = etm_read_alloc_trace_id(drvdata);
• if (ret < 0)

• return ret;
  

• spin_lock(&drvdata->spinlock);

/* @@ -532,6 +581,8 @@ static int etm_enable_sysfs(struct coresight_device *csdev) if (!ret) dev_dbg(&csdev->dev, "ETM tracing enabled\n");

• else

• etm_release_trace_id(drvdata);
  

  return ret; }

@@ -611,6 +662,8 @@ static void etm_disable_perf(struct coresight_device *csdev) coresight_disclaim_device_unlocked(csdev); CS_LOCK(drvdata->base);

• etm_release_trace_id(drvdata); }

static void etm_disable_sysfs(struct coresight_device *csdev) @@ -635,6 +688,13 @@ static void etm_disable_sysfs(struct coresight_device *csdev) spin_unlock(&drvdata->spinlock); cpus_read_unlock();

• /*

• * unlike for perf session - we only release trace IDs when resetting
  

• * sysfs. This permits sysfs users to read the trace ID after the trace
  

• * session has completed. This maintains operational behaviour with
  

• * prior trace id allocation method
  

• */
  

• dev_dbg(&csdev->dev, "ETM tracing disabled\n"); }

@@ -781,11 +841,6 @@ static void etm_init_arch_data(void *info) CS_LOCK(drvdata->base); } -static void etm_init_trace_id(struct etm_drvdata *drvdata) -{

• drvdata->traceid = coresight_get_trace_id(drvdata->cpu);

-}

• static int __init etm_hp_setup(void) { int ret;

@@ -871,7 +926,6 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id) if (etm_arch_supported(drvdata->arch) == false) return -EINVAL;

• etm_init_trace_id(drvdata); etm_set_default(&drvdata->config);

pdata = coresight_get_platform_data(dev); diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c index 68fcbf4ce7a8..962d6ac96d64 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c @@ -86,6 +86,8 @@ static ssize_t reset_store(struct device *dev, etm_set_default(config); spin_unlock(&drvdata->spinlock);

• /* release trace id outside the spinlock as this fn uses it */
  

• etm_release_trace_id(drvdata);
  

  }

return size; @@ -1189,30 +1191,16 @@ static DEVICE_ATTR_RO(cpu); static ssize_t traceid_show(struct device *dev, struct device_attribute *attr, char *buf) {

• unsigned long val;
• struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
• val = etm_get_trace_id(drvdata);
• return sprintf(buf, "%#lx\n", val);

-}

-static ssize_t traceid_store(struct device *dev,

• 	     struct device_attribute *attr,
  

• 	     const char *buf, size_t size)
  

-{

• int ret;
• unsigned long val;

• int trace_id; struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);

• ret = kstrtoul(buf, 16, &val);
• if (ret)

• return ret;
  

• trace_id = etm_read_alloc_trace_id(drvdata);
• if (trace_id < 0)

• return trace_id;
  

• drvdata->traceid = val & ETM_TRACEID_MASK;
• return size;

• return sprintf(buf, "%#x\n", trace_id);

nit: while at this, please could we switch to sysfs_emit(). Rest looks fine to me.

Suzuki