issue ARM-software#2: handle PMCR.X not supported

GJHan3 · Jun 30, 2022 · 3c374e3 · 3c374e3
1 parent c768207
commit 3c374e3
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/include/cs_pmu.h b/include/cs_pmu.h
@@ -112,6 +112,7 @@ int cs_pmu_write_status(cs_device_t, unsigned int flags,
 /**
  *  Control whether the CPU PMU event bus is exported to ETM etc.
  *  Does not affect interrupt generation.
+ *  Return non-zero if the PMU cannot export its events.
  *
  * \param  enable  Indicate whether to enable or disable export.
  */

diff --git a/source/cs_pmu.c b/source/cs_pmu.c
@@ -231,12 +231,22 @@ int cs_pmu_reset(cs_device_t dev, unsigned int flags)
 }
 
 
+/* Update PMCR.X. It may be RAZ/WI, in which case we return an error on enable. */
 int cs_pmu_bus_export(cs_device_t dev, int enable)
 {
+    uint32_t pmcr;
     struct cs_device *d = DEV(dev);
     assert(d->type == DEV_CPU_PMU);
     _cs_unlock(d);
-    return _cs_set_bit(d, CS_PMCR, CS_PMCR_X, enable);
+    pmcr = _cs_read(d, CS_PMCR);
+    if (!enable) {
+        return _cs_write(d, CS_PMCR, pmcr & ~CS_PMCR_X);
+    } else {
+        _cs_write_wo(d, CS_PMCR, pmcr | CS_PMCR_X);
+        pmcr = _cs_read(d, CS_PMCR);
+        /* Return 0 if PMCR.X now reports as set. */
+        return (pmcr & CS_PMCR_X) ? 0 : -1;
+    }
 }