[PATCH 12/24] gtrace: Add RISC-V trace ATB bridge driver
From: Zane Leung
Date: Thu Oct 22 2026 - 23:19:19 EST
Add initial implementation of RISC-V Trace atbbridge driver. The
atbbridge is defined in the RISC-V Trace Control Interface specification.
Signed-off-by: Zane Leung <liangzhen@xxxxxxxxxxxxxxxxxx>
---
drivers/hwtracing/gtrace/Kconfig | 15 ++
drivers/hwtracing/gtrace/Makefile | 1 +
drivers/hwtracing/gtrace/rvtrace-atbbridge.c | 153 +++++++++++++++++++
drivers/hwtracing/gtrace/rvtrace-platform.c | 3 +
drivers/hwtracing/gtrace/rvtrace.h | 1 +
5 files changed, 173 insertions(+)
create mode 100644 drivers/hwtracing/gtrace/rvtrace-atbbridge.c
diff --git a/drivers/hwtracing/gtrace/Kconfig b/drivers/hwtracing/gtrace/Kconfig
index f6026965c54d..3af47d7c3ce3 100644
--- a/drivers/hwtracing/gtrace/Kconfig
+++ b/drivers/hwtracing/gtrace/Kconfig
@@ -71,3 +71,18 @@ config RVTRACE_FUNNEL
To compile this driver as a module, choose M here: the module
will be called rvtrace-funnel.
+
+config RVTRACE_ATBBRIDGE
+ tristate "RISC-V Trace ATB Bridge driver"
+ depends on RVTRACE
+ default y
+ help
+ This driver provides support for the RISC-V trace ATB bridge
+ component which is defined by the RISC-V Trace Control Interface
+ specification. The ATB bridge converts the RISC-V trace stream
+ to the ARM Advanced Trace Bus (ATB) protocol, allowing RISC-V
+ trace sources to feed into ARM CoreSight trace components. It is
+ a link component in the trace path.
+
+ To compile this driver as a module, choose M here: the module
+ will be called rvtrace-atbbridge.
diff --git a/drivers/hwtracing/gtrace/Makefile b/drivers/hwtracing/gtrace/Makefile
index b60d3cfe5248..3f1dcb5664a2 100644
--- a/drivers/hwtracing/gtrace/Makefile
+++ b/drivers/hwtracing/gtrace/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_RVTRACE_ENCODER) += rvtrace-encoder.o
rvtrace-encoder-y := rvtrace-encoder-core.o rvtrace-encoder-sysfs.o
obj-$(CONFIG_RVTRACE_RAMSINK) += rvtrace-ramsink.o
obj-$(CONFIG_RVTRACE_FUNNEL) += rvtrace-funnel.o
+obj-$(CONFIG_RVTRACE_ATBBRIDGE) += rvtrace-atbbridge.o
diff --git a/drivers/hwtracing/gtrace/rvtrace-atbbridge.c b/drivers/hwtracing/gtrace/rvtrace-atbbridge.c
new file mode 100644
index 000000000000..92a59ed80a11
--- /dev/null
+++ b/drivers/hwtracing/gtrace/rvtrace-atbbridge.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026 Spacemit Technologies, Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/gtrace.h>
+#include <linux/idr.h>
+#include <linux/types.h>
+#include <linux/bitfield.h>
+#include "rvtrace.h"
+
+#define RVTRACE_ATBBRIDGE_CTRL_ATID_MASK GENMASK(14, 8)
+#define RVTRACE_ATBBRIDGE_ATID_MIN 0x1
+#define RVTRACE_ATBBRIDGE_ATID_MAX 0x6f
+
+static DEFINE_IDA(rvtrace_atbbridge_atid_ida);
+
+struct rvtrace_atbbridge_priv {
+ int atid;
+};
+
+static int rvtrace_atbbridge_start(struct gtrace_component *comp)
+{
+ int ret;
+
+ ret = gtrace_enable_component(comp);
+ if (ret)
+ dev_err(&comp->dev, "failed to start atbbridge.\n");
+
+ return ret;
+}
+
+static int rvtrace_atbbridge_stop(struct gtrace_component *comp)
+{
+ int ret;
+
+ ret = gtrace_disable_component(comp);
+ if (ret)
+ dev_err(&comp->dev, "failed to stop atbbridge.\n");
+
+ return ret;
+}
+
+static ssize_t cpu_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gtrace_component *comp = to_gtrace_component(dev);
+
+ return sysfs_emit(buf, "%d\n", comp->pdata->bound_cpu);
+}
+static DEVICE_ATTR_RO(cpu);
+
+static ssize_t atid_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gtrace_component *comp = to_gtrace_component(dev);
+ struct rvtrace_atbbridge_priv *priv = dev_get_drvdata(&comp->dev);
+
+ return sysfs_emit(buf, "%u\n", priv->atid);
+}
+static DEVICE_ATTR_RO(atid);
+
+static struct attribute *rvtrace_atbbridge_attrs[] = {
+ &dev_attr_cpu.attr,
+ &dev_attr_atid.attr,
+ NULL,
+};
+
+static const struct attribute_group rvtrace_atbbridge_group = {
+ .attrs = rvtrace_atbbridge_attrs,
+};
+
+const struct attribute_group *rvtrace_atbbridge_groups[] = {
+ &rvtrace_atbbridge_group,
+ NULL,
+};
+EXPORT_SYMBOL_GPL(rvtrace_atbbridge_groups);
+
+static void rvtrace_atbbridge_cleanup(struct gtrace_component *comp)
+{
+ struct rvtrace_atbbridge_priv *priv = dev_get_drvdata(&comp->dev);
+
+ ida_free(&rvtrace_atbbridge_atid_ida, priv->atid);
+}
+
+static int rvtrace_atbbridge_probe(struct gtrace_component *comp)
+{
+ struct rvtrace_atbbridge_priv *priv;
+ u32 val;
+
+ priv = devm_kzalloc(&comp->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->atid = ida_alloc_range(&rvtrace_atbbridge_atid_ida,
+ RVTRACE_ATBBRIDGE_ATID_MIN,
+ RVTRACE_ATBBRIDGE_ATID_MAX,
+ GFP_KERNEL);
+ if (priv->atid < 0) {
+ dev_err(&comp->dev, "failed to allocate ATID.\n");
+ return priv->atid;
+ }
+
+ val = gtrace_read32(comp->pdata, RVTRACE_COMPONENT_CTRL_OFFSET);
+ val &= ~RVTRACE_ATBBRIDGE_CTRL_ATID_MASK;
+ val |= FIELD_PREP(RVTRACE_ATBBRIDGE_CTRL_ATID_MASK, priv->atid);
+ gtrace_write32(comp->pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET);
+
+ dev_set_drvdata(&comp->dev, priv);
+
+ return 0;
+}
+
+static void rvtrace_atbbridge_remove(struct gtrace_component *comp)
+{
+ rvtrace_atbbridge_cleanup(comp);
+}
+
+static const struct gtrace_component_id rvtrace_atbbridge_ids[] = {
+ { .type = GTRACE_RVTRACE_ATBBRIDGE,
+ .version = rvtrace_component_mkversion(1, 0), },
+ {},
+};
+
+static struct gtrace_driver rvtrace_atbbridge_driver = {
+ .id_table = rvtrace_atbbridge_ids,
+ .probe = rvtrace_atbbridge_probe,
+ .remove = rvtrace_atbbridge_remove,
+ .start = rvtrace_atbbridge_start,
+ .stop = rvtrace_atbbridge_stop,
+ .driver = {
+ .name = "rvtrace-atbbridge",
+ },
+};
+
+static int __init rvtrace_atbbridge_init(void)
+{
+ return gtrace_register_driver(&rvtrace_atbbridge_driver);
+}
+
+static void __exit rvtrace_atbbridge_exit(void)
+{
+ gtrace_unregister_driver(&rvtrace_atbbridge_driver);
+ ida_destroy(&rvtrace_atbbridge_atid_ida);
+}
+
+module_init(rvtrace_atbbridge_init);
+module_exit(rvtrace_atbbridge_exit);
+
+MODULE_AUTHOR("Zane Leung");
+MODULE_DESCRIPTION("RISC-V Trace ATB Bridge Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hwtracing/gtrace/rvtrace-platform.c b/drivers/hwtracing/gtrace/rvtrace-platform.c
index ad8daa06e13e..9bd315867082 100644
--- a/drivers/hwtracing/gtrace/rvtrace-platform.c
+++ b/drivers/hwtracing/gtrace/rvtrace-platform.c
@@ -136,6 +136,9 @@ static int rvtrace_platform_probe(struct platform_device *pdev)
case GTRACE_RVTRACE_FUNNEL:
pdata->groups = rvtrace_funnel_groups;
break;
+ case GTRACE_RVTRACE_ATBBRIDGE:
+ pdata->groups = rvtrace_atbbridge_groups;
+ break;
default:
pdata->groups = NULL;
}
diff --git a/drivers/hwtracing/gtrace/rvtrace.h b/drivers/hwtracing/gtrace/rvtrace.h
index a345ba110267..5cbe3405e274 100644
--- a/drivers/hwtracing/gtrace/rvtrace.h
+++ b/drivers/hwtracing/gtrace/rvtrace.h
@@ -121,5 +121,6 @@ extern const struct gtrace_hw_ops rvtrace_hw_ops;
/* Sysfs attribute groups for RISC-V trace components */
extern const struct attribute_group *rvtrace_encoder_groups[];
extern const struct attribute_group *rvtrace_funnel_groups[];
+extern const struct attribute_group *rvtrace_atbbridge_groups[];
#endif /* __LINUX_RVTRACE_H__ */
--
2.34.1