coresight: etm3: Add support for handling errors

Add support for reporting errors back from the SMP cross
function call for enabling ETM.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index 9ce8fba..206c238 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -355,11 +355,10 @@ static int etm_parse_event_config(struct etm_drvdata *drvdata,
        return 0;
 }
 
-static void etm_enable_hw(void *info)
+static int etm_enable_hw(struct etm_drvdata *drvdata)
 {
        int i;
        u32 etmcr;
-       struct etm_drvdata *drvdata = info;
        struct etm_config *config = &drvdata->config;
 
        CS_UNLOCK(drvdata->base);
@@ -421,6 +420,21 @@ static void etm_enable_hw(void *info)
        CS_LOCK(drvdata->base);
 
        dev_dbg(drvdata->dev, "cpu: %d enable smp call done\n", drvdata->cpu);
+       return 0;
+}
+
+struct etm_enable_arg {
+       struct etm_drvdata *drvdata;
+       int rc;
+};
+
+static void etm_enable_hw_smp_call(void *info)
+{
+       struct etm_enable_arg *arg = info;
+
+       if (WARN_ON(!arg))
+               return;
+       arg->rc = etm_enable_hw(arg->drvdata);
 }
 
 static int etm_cpu_id(struct coresight_device *csdev)
@@ -475,14 +489,13 @@ static int etm_enable_perf(struct coresight_device *csdev,
        /* Configure the tracer based on the session's specifics */
        etm_parse_event_config(drvdata, event);
        /* And enable it */
-       etm_enable_hw(drvdata);
-
-       return 0;
+       return etm_enable_hw(drvdata);
 }
 
 static int etm_enable_sysfs(struct coresight_device *csdev)
 {
        struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+       struct etm_enable_arg arg = { 0 };
        int ret;
 
        spin_lock(&drvdata->spinlock);
@@ -492,20 +505,21 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
         * hw configuration will take place on the local CPU during bring up.
         */
        if (cpu_online(drvdata->cpu)) {
+               arg.drvdata = drvdata;
                ret = smp_call_function_single(drvdata->cpu,
-                                              etm_enable_hw, drvdata, 1);
-               if (ret)
-                       goto err;
+                                              etm_enable_hw_smp_call, &arg, 1);
+               if (!ret)
+                       ret = arg.rc;
+               if (!ret)
+                       drvdata->sticky_enable = true;
+       } else {
+               ret = -ENODEV;
        }
 
-       drvdata->sticky_enable = true;
        spin_unlock(&drvdata->spinlock);
 
-       dev_dbg(drvdata->dev, "ETM tracing enabled\n");
-       return 0;
-
-err:
-       spin_unlock(&drvdata->spinlock);
+       if (!ret)
+               dev_dbg(drvdata->dev, "ETM tracing enabled\n");
        return ret;
 }