coresight: etm4x: Modify core-commit to avoid HiSilicon ETM overflow

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 <[e-mail]>
Signed-off-by: Qi Liu <[e-mail]>
[Modified changelog title and Kconfig description]
Signed-off-by: Mathieu Poirier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/hwtracing/coresight/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called coresight-etm4x.
 
+config ETM4X_IMPDEF_FEATURE
+	bool "Control implementation defined overflow support in ETM 4.x driver"
+	depends on CORESIGHT_SOURCE_ETM4X
+	help
+	  This control provides implementation define control for CoreSight
+	  ETM 4.x tracer module that can't reduce commit rate automatically.
+	  This avoids overflow between the ETM tracer module and the cpu core.
+
 config CORESIGHT_STM
 	tristate "CoreSight System Trace Macrocell driver"
 	depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64

drivers/hwtracing/coresight/coresight-etm4x-core.c

···
  * 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>
···
 #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>
 
···
 	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;
···
 	struct device *etm_dev = &drvdata->csdev->dev;
 
 	CS_UNLOCK(drvdata->base);
+	etm4_enable_arch_specific(drvdata);
 
 	etm4_os_unlock(drvdata);
 
···
 	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 */
···
 		coresight_enable(drvdata->csdev);
 		drvdata->boot_enable = true;
 	}
+
+	etm4_check_arch_features(drvdata, id->id);
 
 	return 0;
 }

drivers/hwtracing/coresight/coresight-etm4x.h

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