coresight: etm4x: Fix number of resources check for ETM 4.3 and above

The initialisation code checks TRCIDR4 to determine the number of resource
selectors available on the system. Since ETM v 4.3, the value 0 has a
different meaning. This patch takes into account this change.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
[Removed '.' in patch title, added stable]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200916191737.4001561-17-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index b29ad4f..f5ab13a 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -742,8 +742,14 @@ static void etm4_init_arch_data(void *info)
         * The number of resource pairs conveyed by the HW starts at 0, i.e a
         * value of 0x0 indicate 1 resource pair, 0x1 indicate two and so on.
         * As such add 1 to the value of NUMRSPAIR for a better representation.
+        *
+        * For ETM v4.3 and later, 0x0 means 0, and no pairs are available -
+        * the default TRUE and FALSE resource selectors are omitted.
+        * Otherwise for values 0x1 and above the number is N + 1 as per v4.2.
         */
-       drvdata->nr_resource = BMVAL(etmidr4, 16, 19) + 1;
+       drvdata->nr_resource = BMVAL(etmidr4, 16, 19);
+       if ((drvdata->arch < ETM4X_ARCH_4V3) || (drvdata->nr_resource > 0))
+               drvdata->nr_resource += 1;
        /*
         * NUMSSCC, bits[23:20] the number of single-shot
         * comparator control for tracing. Read any status regs as these

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 5259f96..eefc737 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -200,6 +200,9 @@
 /* NS MON (EL3) mode never implemented */
 #define ETM_EXLEVEL_NS_VICTLR_MASK     GENMASK(22, 20)
 
+/* Interpretation of resource numbers change at ETM v4.3 architecture */
+#define ETM4X_ARCH_4V3 0x43
+
 /**
  * struct etmv4_config - configuration information related to an ETMv4
  * @mode:      Controls various modes supported by this ETM.