The ETM device can't keep up with the core pipeline when cpu core
is at full speed. This may cause overflow within core and its ETM.
This is a common phenomenon on ETM devices.

On HiSilicon Hip08 platform, a specific feature is added to set
core pipeline. So commit rate can be reduced manually to avoid ETM
overflow.

Reviewed-by: Suzuki K Poulose <suzuki.poul...@arm.com>
Signed-off-by: Qi Liu <liuqi...@huawei.com>
---
Change since v1:
- add CONFIG_ETM4X_IMPDEF_FEATURE and CONFIG_ETM4X_IMPDEF_HISILICON
  to keep specific feature off platforms which don't use it.
Change since v2:
- remove some unused variable.
Change since v3:
- use read/write_sysreg_s() to access register.
Change since v4:
- rename the call back function to a more generic name, and fix some
  compile warnings.
Change since v5:
- add function comments about HISI_HIP08_CORE_COMMIT_REG, and use
  explicitly masked values when update register.

 drivers/hwtracing/coresight/Kconfig                |  9 ++
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 98 ++++++++++++++++++++++
 drivers/hwtracing/coresight/coresight-etm4x.h      |  8 ++
 3 files changed, 115 insertions(+)

diff --git a/drivers/hwtracing/coresight/Kconfig 
b/drivers/hwtracing/coresight/Kconfig
index c119824..1cc3601 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -110,6 +110,15 @@ config CORESIGHT_SOURCE_ETM4X
          To compile this driver as a module, choose M here: the
          module will be called coresight-etm4x.

+config ETM4X_IMPDEF_FEATURE
+       bool "Control overflow impdef support in CoreSight ETM 4.x driver "
+       depends on CORESIGHT_SOURCE_ETM4X
+       help
+         This control provides overflow implement define for CoreSight
+         ETM 4.x tracer module which could not reduce commit race
+         automatically, and could avoid overflow within ETM tracer module
+         and its cpu core.
+
 config CORESIGHT_STM
        tristate "CoreSight System Trace Macrocell driver"
        depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c 
b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index abd706b..0cbc92a 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2014, The Linux Foundation. All rights reserved.
  */

+#include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
@@ -28,7 +29,9 @@
 #include <linux/perf_event.h>
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
+
 #include <asm/sections.h>
+#include <asm/sysreg.h>
 #include <asm/local.h>
 #include <asm/virt.h>

@@ -103,6 +106,97 @@ struct etm4_enable_arg {
        int rc;
 };

+#ifdef CONFIG_ETM4X_IMPDEF_FEATURE
+
+#define HISI_HIP08_AMBA_ID             0x000b6d01
+#define ETM4_AMBA_MASK                 0xfffff
+#define HISI_HIP08_CORE_COMMIT_MASK    0x3000
+#define HISI_HIP08_CORE_COMMIT_SHIFT   12
+#define HISI_HIP08_CORE_COMMIT_FULL    0b00
+#define HISI_HIP08_CORE_COMMIT_LVL_1   0b01
+#define HISI_HIP08_CORE_COMMIT_REG     sys_reg(3, 1, 15, 2, 5)
+
+struct etm4_arch_features {
+       void (*arch_callback)(bool enable);
+};
+
+static bool etm4_hisi_match_pid(unsigned int id)
+{
+       return (id & ETM4_AMBA_MASK) == HISI_HIP08_AMBA_ID;
+}
+
+static void etm4_hisi_config_core_commit(bool enable)
+{
+       u8 commit = enable ? HISI_HIP08_CORE_COMMIT_LVL_1 :
+                   HISI_HIP08_CORE_COMMIT_FULL;
+       u64 val;
+
+       /*
+        * bit 12 and 13 of HISI_HIP08_CORE_COMMIT_REG are used together
+        * to set core-commit, 2'b00 means cpu is at full speed, 2'b01,
+        * 2'b10, 2'b11 mean reduce pipeline speed, and 2'b01 means level-1
+        * speed(minimun value). So bit 12 and 13 should be cleared together.
+        */
+       val = read_sysreg_s(HISI_HIP08_CORE_COMMIT_REG);
+       val &= ~HISI_HIP08_CORE_COMMIT_MASK;
+       val |= commit << HISI_HIP08_CORE_COMMIT_SHIFT;
+       write_sysreg_s(val, HISI_HIP08_CORE_COMMIT_REG);
+}
+
+static struct etm4_arch_features etm4_features[] = {
+       [ETM4_IMPDEF_HISI_CORE_COMMIT] = {
+               .arch_callback = etm4_hisi_config_core_commit,
+       },
+       {},
+};
+
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+       struct etm4_arch_features *ftr;
+       int bit;
+
+       for_each_set_bit(bit, drvdata->arch_features, ETM4_IMPDEF_FEATURE_MAX) {
+               ftr = &etm4_features[bit];
+
+               if (ftr->arch_callback)
+                       ftr->arch_callback(true);
+       }
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+       struct etm4_arch_features *ftr;
+       int bit;
+
+       for_each_set_bit(bit, drvdata->arch_features, ETM4_IMPDEF_FEATURE_MAX) {
+               ftr = &etm4_features[bit];
+
+               if (ftr->arch_callback)
+                       ftr->arch_callback(false);
+       }
+}
+
+static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
+                                     unsigned int id)
+{
+       if (etm4_hisi_match_pid(id))
+               set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
+}
+#else
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+
+static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
+                                    unsigned int id)
+{
+}
+#endif /* CONFIG_ETM4X_IMPDEF_FEATURE */
+
 static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 {
        int i, rc;
@@ -110,6 +204,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
        struct device *etm_dev = &drvdata->csdev->dev;

        CS_UNLOCK(drvdata->base);
+       etm4_enable_arch_specific(drvdata);

        etm4_os_unlock(drvdata);

@@ -476,6 +571,7 @@ static void etm4_disable_hw(void *info)
        int i;

        CS_UNLOCK(drvdata->base);
+       etm4_disable_arch_specific(drvdata);

        if (!drvdata->skip_power_up) {
                /* power can be removed from the trace unit now */
@@ -1547,6 +1643,8 @@ static int etm4_probe(struct amba_device *adev, const 
struct amba_id *id)
                drvdata->boot_enable = true;
        }

+       etm4_check_arch_features(drvdata, id->id);
+
        return 0;
 }

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h 
b/drivers/hwtracing/coresight/coresight-etm4x.h
index eefc737..3dd3e06 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -8,6 +8,7 @@

 #include <asm/local.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
 #include "coresight-priv.h"

 /*
@@ -203,6 +204,11 @@
 /* Interpretation of resource numbers change at ETM v4.3 architecture */
 #define ETM4X_ARCH_4V3 0x43

+enum etm_impdef_type {
+       ETM4_IMPDEF_HISI_CORE_COMMIT,
+       ETM4_IMPDEF_FEATURE_MAX,
+};
+
 /**
  * struct etmv4_config - configuration information related to an ETMv4
  * @mode:      Controls various modes supported by this ETM.
@@ -415,6 +421,7 @@ struct etmv4_save_state {
  * @state_needs_restore: True when there is context to restore after PM exit
  * @skip_power_up: Indicates if an implementation can skip powering up
  *                the trace unit.
+ * @arch_features: Bitmap of arch features of etmv4 devices.
  */
 struct etmv4_drvdata {
        void __iomem                    *base;
@@ -463,6 +470,7 @@ struct etmv4_drvdata {
        struct etmv4_save_state         *save_state;
        bool                            state_needs_restore;
        bool                            skip_power_up;
+       DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
 };

 /* Address comparator access types */
--
2.8.1

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