[RFC PATCH 05/12] coresight: Add RISC-V Trace ATB Bridge driver
Zane Leung
liangzhen at linux.spacemit.com
Mon Apr 13 20:41:46 PDT 2026
From: liangzhen <zhen.liang at spacemit.com>
Add initial implementation of RISC-V trace ATB
Bridge driver. The ATB Bridge is defined in the
RISC-V Trace Control Interface specification.
Signed-off-by: liangzhen <zhen.liang at spacemit.com>
---
drivers/hwtracing/coresight/Kconfig | 12 +
drivers/hwtracing/coresight/Makefile | 1 +
.../hwtracing/coresight/rvtrace-atbbridge.c | 239 ++++++++++++++++++
3 files changed, 252 insertions(+)
create mode 100644 drivers/hwtracing/coresight/rvtrace-atbbridge.c
diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 8381a84e2699..1cd88a1a7d08 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -288,6 +288,17 @@ config RVTRACE
dynamically aggregated with CoreSight trace infrastructure
at run time to form a complete trace path.
+config RVTRACE_ATBBRIDGE
+ tristate "RISCV Trace ATB Bridge driver"
+ depends on RVTRACE
+ help
+ This driver provides support for the ATB Bridge driver. The ATB
+ Bridge allows sending RISC-V trace to Arm CoreSight infrastructure
+ (instead of RISC-V compliant sink) as an ATB initiator.
+
+ To compile this driver as a module, choose M here: the module
+ will be called rvtrace-atbbridge.
+
config RVTRACE_FUNNEL
tristate "RISCV Trace Funnel driver"
depends on RVTRACE
@@ -303,6 +314,7 @@ config RVTRACE_ENCODER
tristate "RISCV Trace Encoder driver"
depends on RVTRACE
select RVTRACE_FUNNEL
+ select RVTRACE_ATBBRIDGE
help
This driver provides support for the Trace Encoder module, tracing
the instructions that a processor is executing. This is primarily
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 409a0abf0642..2264a313a773 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -59,6 +59,7 @@ coresight-ctcu-y := coresight-ctcu-core.o
obj-$(CONFIG_CORESIGHT_KUNIT_TESTS) += coresight-kunit-tests.o
obj-$(CONFIG_RVTRACE) += rvtrace.o
rvtrace-y := rvtrace-core.o
+obj-$(CONFIG_RVTRACE_ATBBRIDGE) += rvtrace-atbbridge.o
obj-$(CONFIG_RVTRACE_FUNNEL) += rvtrace-funnel.o
obj-$(CONFIG_RVTRACE_ENCODER) += rvtrace-encoder.o
rvtrace-encoder-y := rvtrace-encoder-core.o rvtrace-encoder-sysfs.o
diff --git a/drivers/hwtracing/coresight/rvtrace-atbbridge.c b/drivers/hwtracing/coresight/rvtrace-atbbridge.c
new file mode 100644
index 000000000000..a931be322a2f
--- /dev/null
+++ b/drivers/hwtracing/coresight/rvtrace-atbbridge.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(C) 2026 Spacemit Limited. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/coresight.h>
+#include <linux/platform_device.h>
+#include <linux/bitfield.h>
+#include <linux/rvtrace.h>
+
+#include "coresight-priv.h"
+#include "coresight-trace-id.h"
+
+#define RVTRACE_ATBBRIDGE_CONTROL_ID_MASK GENMASK(14, 8)
+/**
+ * struct atbbridge_data - specifics associated to a ATB bridge component
+ * @csdev: Component vitals needed by the framework.
+ * @spinlock: Only one at a time pls.
+ * @traceid: Value of the current ID for this component.
+ */
+struct atbbridge_data {
+ struct coresight_device *csdev;
+ spinlock_t spinlock;
+ u8 traceid;
+};
+
+DEFINE_CORESIGHT_DEVLIST(atbbridge_devs, "atbbridge");
+
+static int atbbridge_enable(struct coresight_device *csdev,
+ struct coresight_connection *in,
+ struct coresight_connection *out)
+{
+ u32 control;
+ int ret = 0;
+ struct rvtrace_component *comp = dev_get_drvdata(csdev->dev.parent);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+ unsigned long flags;
+
+ spin_lock_irqsave(&atbbridge_data->spinlock, flags);
+ if (!comp->was_reset) {
+ ret = rvtrace_component_reset(comp);
+ if (ret)
+ goto done;
+ }
+
+ control = readl_relaxed(comp->base + RVTRACE_COMPONENT_CTRL_OFFSET);
+ control |= FIELD_PREP(RVTRACE_ATBBRIDGE_CONTROL_ID_MASK, atbbridge_data->traceid);
+ writel_relaxed(control, comp->base + RVTRACE_COMPONENT_CTRL_OFFSET);
+
+ ret = rvtrace_enable_component(comp);
+ if (ret)
+ goto done;
+
+ spin_unlock_irqrestore(&atbbridge_data->spinlock, flags);
+
+ dev_dbg(&csdev->dev, "Trace ATB bridge enabled\n");
+done:
+ return ret;
+}
+
+static void atbbridge_disable(struct coresight_device *csdev,
+ struct coresight_connection *in,
+ struct coresight_connection *out)
+{
+ struct rvtrace_component *comp = dev_get_drvdata(csdev->dev.parent);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+ unsigned long flags;
+
+ spin_lock_irqsave(&atbbridge_data->spinlock, flags);
+
+ if (rvtrace_disable_component(comp))
+ dev_err(&csdev->dev,
+ "timeout while waiting for Trace ATB Bridge to be disabled\n");
+
+ if (rvtrace_comp_is_empty(comp))
+ dev_err(&csdev->dev,
+ "timeout while waiting for Trace ATB Bridge internal buffers become empty\n");
+
+ spin_unlock_irqrestore(&atbbridge_data->spinlock, flags);
+
+ dev_dbg(&csdev->dev, "Trace ATB bridge disabled\n");
+}
+
+static int atbbridge_link_trace_id(struct coresight_device *csdev, __maybe_unused enum cs_mode mode,
+ __maybe_unused struct coresight_device *sink)
+{
+ struct rvtrace_component *comp = dev_get_drvdata(csdev->dev.parent);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+
+ return atbbridge_data->traceid;
+}
+
+static const struct coresight_ops_link atbbridge_link_ops = {
+ .enable = atbbridge_enable,
+ .disable = atbbridge_disable,
+};
+
+static const struct coresight_ops atbbridge_cs_ops = {
+ .trace_id = atbbridge_link_trace_id,
+ .link_ops = &atbbridge_link_ops,
+};
+
+static ssize_t reset_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ unsigned long val;
+ struct rvtrace_component *comp = dev_get_drvdata(dev->parent);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+ unsigned long flags;
+
+ if (kstrtoul(buf, 16, &val))
+ return -EINVAL;
+
+ if (val) {
+ if (rvtrace_component_reset(comp)) {
+ comp->was_reset = false;
+ spin_unlock_irqrestore(&atbbridge_data->spinlock, flags);
+ return -EINVAL;
+ }
+ }
+
+ spin_unlock_irqrestore(&atbbridge_data->spinlock, flags);
+
+ return size;
+}
+static DEVICE_ATTR_WO(reset);
+
+static ssize_t cpu_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ unsigned long val;
+ struct rvtrace_component *comp = dev_get_drvdata(dev->parent);
+
+ val = comp->cpu;
+ return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+static DEVICE_ATTR_RO(cpu);
+
+static ssize_t traceid_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ unsigned long val;
+ struct rvtrace_component *comp = dev_get_drvdata(dev->parent);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+
+ val = atbbridge_data->traceid;
+ return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+static DEVICE_ATTR_RO(traceid);
+
+static struct attribute *trace_atbbridge_attrs[] = {
+ coresight_simple_reg32(control, RVTRACE_COMPONENT_CTRL_OFFSET),
+ coresight_simple_reg32(impl, RVTRACE_COMPONENT_IMPL_OFFSET),
+ &dev_attr_reset.attr,
+ &dev_attr_cpu.attr,
+ &dev_attr_traceid.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(trace_atbbridge);
+
+static int atbbridge_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct coresight_platform_data *pdata;
+ struct atbbridge_data *atbbridge_data;
+ struct rvtrace_component *comp;
+ struct coresight_desc desc = { 0 };
+ int trace_id = 0;
+
+ comp = rvtrace_register_component(pdev);
+ if (IS_ERR(comp))
+ return PTR_ERR(comp);
+
+ atbbridge_data = devm_kzalloc(dev, sizeof(*atbbridge_data), GFP_KERNEL);
+ if (!atbbridge_data)
+ return -ENOMEM;
+
+ spin_lock_init(&atbbridge_data->spinlock);
+
+ pdata = coresight_get_platform_data(dev);
+ if (IS_ERR(pdata))
+ return PTR_ERR(pdata);
+ pdev->dev.platform_data = pdata;
+
+ platform_set_drvdata(pdev, comp);
+
+ desc.name = coresight_alloc_device_name(&atbbridge_devs, dev);
+ desc.access = CSDEV_ACCESS_IOMEM(comp->base);
+ desc.type = CORESIGHT_DEV_TYPE_LINK;
+ desc.subtype.link_subtype = CORESIGHT_DEV_SUBTYPE_LINK_FIFO;
+ desc.ops = &atbbridge_cs_ops;
+ desc.pdata = pdata;
+ desc.dev = dev;
+ desc.groups = trace_atbbridge_groups;
+ atbbridge_data->csdev = coresight_register(&desc);
+ if (IS_ERR(atbbridge_data->csdev))
+ return PTR_ERR(atbbridge_data->csdev);
+
+ trace_id = coresight_trace_id_get_system_id();
+ if (trace_id < 0)
+ return -EINVAL;
+ atbbridge_data->traceid = (u8)trace_id;
+
+ comp->id.data = atbbridge_data;
+
+ dev_dbg(dev, "Trace ATB Bridge initialized\n");
+
+ return 0;
+}
+
+static void atbbridge_remove(struct platform_device *pdev)
+{
+ struct rvtrace_component *comp = platform_get_drvdata(pdev);
+ struct atbbridge_data *atbbridge_data = rvtrace_component_data(comp);
+
+ coresight_trace_id_put_system_id(atbbridge_data->traceid);
+ coresight_unregister(atbbridge_data->csdev);
+}
+
+static const struct of_device_id atbbridge_match[] = {
+ {.compatible = "riscv,trace-atbbridge"},
+ {},
+};
+
+static struct platform_driver atbbridge_driver = {
+ .probe = atbbridge_probe,
+ .remove = atbbridge_remove,
+ .driver = {
+ .name = "trace-atbbridge",
+ .of_match_table = atbbridge_match,
+ },
+};
+
+module_platform_driver(atbbridge_driver);
+
+MODULE_DESCRIPTION("RISC-V Trace ATB Bridge driver");
+MODULE_LICENSE("GPL");
--
2.34.1
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