1 files changed, 71 insertions, 0 deletions

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index ebaefb45130f..4db8d6a4d0cb 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -335,12 +335,25 @@ static void etm4_disable_hw(void *info)
 static int etm4_disable_perf(struct coresight_device *csdev,
                              struct perf_event *event)
 {
+        u32 control;
+        struct etm_filters *filters = event->hw.addr_filters;
         struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
         if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
                 return -EINVAL;
 
         etm4_disable_hw(drvdata);
+
+        /*
+         * Check if the start/stop logic was active when the unit was stopped.
+         * That way we can re-enable the start/stop logic when the process is
+         * scheduled again.  Configuration of the start/stop logic happens in
+         * function etm4_set_event_filters().
+         */
+        control = readl_relaxed(drvdata->base + TRCVICTLR);
+        /* TRCVICTLR::SSSTATUS, bit[9] */
+        filters->ssstatus = (control & BIT(9));
+
         return 0;
 }
 
@@ -657,6 +670,27 @@ static void etm4_set_comparator_filter(struct etmv4_config *config,
         config->viiectlr |= BIT(comparator / 2);
 }
 
+static void etm4_set_start_stop_filter(struct etmv4_config *config,
+                                       u64 address, int comparator,
+                                       enum etm_addr_type type)
+{
+        int shift;
+        u64 access_type = etm4_get_access_type(config);
+
+        /* Configure the comparator */
+        config->addr_val[comparator] = address;
+        config->addr_acc[comparator] = access_type;
+        config->addr_type[comparator] = type;
+
+        /*
+         * Configure ViewInst Start-Stop control register.
+         * Addresses configured to start tracing go from bit 0 to n-1,
+         * while those configured to stop tracing from 16 to 16 + n-1.
+         */
+        shift = (type == ETM_ADDR_TYPE_START ? 0 : 16);
+        config->vissctlr |= BIT(shift + comparator);
+}
+
 static void etm4_set_default_filter(struct etmv4_config *config)
 {
         u64 start, stop;
@@ -721,6 +755,14 @@ static int etm4_get_next_comparator(struct etmv4_drvdata *drvdata, u32 type)
                         /* Address range comparators go in pairs */
                         index += 2;
                         break;
+                case ETM_ADDR_TYPE_START:
+                case ETM_ADDR_TYPE_STOP:
+                        if (config->addr_type[index] == ETM_ADDR_TYPE_NONE)
+                                return index;
+
+                        /* Start/stop address can have odd indexes */
+                        index += 1;
+                        break;
                 default:
                         return -EINVAL;
                 }
@@ -734,6 +776,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
                                   struct perf_event *event)
 {
         int i, comparator, ret = 0;
+        u64 address;
         struct etmv4_config *config = &drvdata->config;
         struct etm_filters *filters = event->hw.addr_filters;
 
@@ -776,6 +819,34 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
                         /* No start-stop filtering for ViewInst */
                         config->vissctlr = 0x0;
                         break;
+                case ETM_ADDR_TYPE_START:
+                case ETM_ADDR_TYPE_STOP:
+                        /* Get the right start or stop address */
+                        address = (type == ETM_ADDR_TYPE_START ?
+                                   filter->start_addr :
+                                   filter->stop_addr);
+
+                        /* Configure comparator */
+                        etm4_set_start_stop_filter(config, address,
+                                                   comparator, type);
+
+                        /*
+                         * If filters::ssstatus == 1, trace acquisition was
+                         * started but the process was yanked away before the
+                         * the stop address was hit.  As such the start/stop
+                         * logic needs to be re-started so that tracing can
+                         * resume where it left.
+                         *
+                         * The start/stop logic status when a process is
+                         * scheduled out is checked in function
+                         * etm4_disable_perf().
+                         */
+                        if (filters->ssstatus)
+                                config->vinst_ctrl |= BIT(9);
+
+                        /* No include/exclude filtering for ViewInst */
+                        config->viiectlr = 0x0;
+                        break;
                 default:
                         ret = -EINVAL;
                         goto out;