[PATCH 10/24] gtrace: Add RISC-V trace funnel driver
Zane Leung
liangzhen at linux.spacemit.com
Thu Oct 22 20:14:51 PDT 2026
Add initial implementation of RISC-V Trace funnel driver. The funnel
is defined in the RISC-V Trace Control Interface specification.
Signed-off-by: Zane Leung <liangzhen at linux.spacemit.com>
---
drivers/hwtracing/gtrace/Kconfig | 14 ++
drivers/hwtracing/gtrace/Makefile | 1 +
drivers/hwtracing/gtrace/rvtrace-funnel.c | 165 ++++++++++++++++++++
drivers/hwtracing/gtrace/rvtrace-funnel.h | 21 +++
drivers/hwtracing/gtrace/rvtrace-platform.c | 3 +
drivers/hwtracing/gtrace/rvtrace.h | 1 +
6 files changed, 205 insertions(+)
create mode 100644 drivers/hwtracing/gtrace/rvtrace-funnel.c
create mode 100644 drivers/hwtracing/gtrace/rvtrace-funnel.h
diff --git a/drivers/hwtracing/gtrace/Kconfig b/drivers/hwtracing/gtrace/Kconfig
index e5b62d65e2fd..f6026965c54d 100644
--- a/drivers/hwtracing/gtrace/Kconfig
+++ b/drivers/hwtracing/gtrace/Kconfig
@@ -57,3 +57,17 @@ config RVTRACE_RAMSINK
To compile this driver as a module, choose M here: the module
will be called rvtrace-ramsink.
+
+config RVTRACE_FUNNEL
+ tristate "RISC-V Trace Funnel driver"
+ depends on RVTRACE
+ default y
+ help
+ This driver provides support for the RISC-V trace funnel component
+ which is defined by the RISC-V Trace Control Interface specification.
+ The funnel merges trace data from multiple input ports into a single
+ output stream. It is a link component in the trace path between
+ sources and sinks.
+
+ To compile this driver as a module, choose M here: the module
+ will be called rvtrace-funnel.
diff --git a/drivers/hwtracing/gtrace/Makefile b/drivers/hwtracing/gtrace/Makefile
index 87cb5add78d4..9c99d917b9f4 100644
--- a/drivers/hwtracing/gtrace/Makefile
+++ b/drivers/hwtracing/gtrace/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_RVTRACE) += rvtrace-platform.o
obj-$(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
diff --git a/drivers/hwtracing/gtrace/rvtrace-funnel.c b/drivers/hwtracing/gtrace/rvtrace-funnel.c
new file mode 100644
index 000000000000..941cd3360395
--- /dev/null
+++ b/drivers/hwtracing/gtrace/rvtrace-funnel.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026 Spacemit Technologies, Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/gtrace.h>
+#include <linux/types.h>
+#include "rvtrace.h"
+#include "rvtrace-funnel.h"
+
+static int rvtrace_funnel_start(struct gtrace_component *comp)
+{
+ int ret;
+
+ ret = gtrace_enable_component(comp);
+ if (ret)
+ dev_err(&comp->dev, "failed to start rvtrace funnel.\n");
+
+ return ret;
+}
+
+static int rvtrace_funnel_stop(struct gtrace_component *comp)
+{
+ struct rvtrace_funnel_priv *priv = dev_get_drvdata(&comp->dev);
+ int ret;
+
+ ret = gtrace_disable_component(comp);
+ if (ret) {
+ dev_err(&comp->dev, "failed to stop rvtrace funnel.\n");
+ return ret;
+ }
+
+ if (priv->disinput_mask)
+ gtrace_write32(comp->pdata, RVTRACE_FUNNEL_DISINPUT_MASK,
+ RVTRACE_FUNNEL_DISINPUT_OFFSET);
+
+ return 0;
+}
+
+static int _rvtrace_funnel_start_port(struct gtrace_component *comp, int port)
+{
+ struct gtrace_platform_data *pdata = comp->pdata;
+ struct rvtrace_funnel_priv *priv = dev_get_drvdata(&comp->dev);
+ u32 disinput;
+ int ret;
+
+ if (!(priv->disinput_mask & BIT(port)))
+ return 0;
+
+ disinput = gtrace_read32(pdata, RVTRACE_FUNNEL_DISINPUT_OFFSET);
+ disinput &= ~BIT(port);
+ gtrace_write32(pdata, disinput, RVTRACE_FUNNEL_DISINPUT_OFFSET);
+ ret = gtrace_poll_bit(pdata, RVTRACE_FUNNEL_DISINPUT_OFFSET,
+ port, 0, comp->pdata->control_poll_timeout_usecs);
+ if (ret)
+ dev_err(&comp->dev, "failed to enable rvtrace funnel inport %d.\n", port);
+
+ return ret;
+}
+
+static int rvtrace_funnel_start_port(struct gtrace_component *comp,
+ struct gtrace_connection *in,
+ struct gtrace_connection *out)
+{
+ int ret = 0;
+
+ if (in->dest_refcnt == 0)
+ ret = _rvtrace_funnel_start_port(comp, in->dest_port);
+ if (!ret)
+ in->dest_refcnt++;
+
+ return ret;
+}
+
+static void rvtrace_funnel_stop_port(struct gtrace_component *comp,
+ struct gtrace_connection *in,
+ struct gtrace_connection *out)
+{
+ /*
+ * Setting trFunnelEnable to 0 flushes any queued trace data to output.
+ * Due to this flush behavior of the RISC-V trace funnel during component
+ * disablement, we do not disable individual ports here. Instead, we
+ * defer it and disable all ports at once when the entire component is
+ * stopped. For now, we only need to decrement the reference count.
+ */
+ --in->dest_refcnt;
+}
+
+static ssize_t disinput_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ u32 val;
+ struct gtrace_component *comp = to_gtrace_component(dev);
+
+ val = gtrace_read32(comp->pdata, RVTRACE_FUNNEL_DISINPUT_OFFSET);
+
+ return scnprintf(buf, PAGE_SIZE, "0x%x\n", val);
+}
+static DEVICE_ATTR_RO(disinput);
+
+static struct attribute *rvtrace_funnel_attrs[] = {
+ &dev_attr_disinput.attr,
+ NULL,
+};
+
+static struct attribute_group rvtrace_funnel_group = {
+ .attrs = rvtrace_funnel_attrs,
+};
+
+const struct attribute_group *rvtrace_funnel_groups[] = {
+ &rvtrace_funnel_group,
+ NULL,
+};
+EXPORT_SYMBOL_GPL(rvtrace_funnel_groups);
+
+static int rvtrace_funnel_probe(struct gtrace_component *comp)
+{
+ struct gtrace_platform_data *pdata = comp->pdata;
+ struct rvtrace_funnel_priv *priv;
+
+ priv = devm_kzalloc(&comp->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ gtrace_write32(pdata, RVTRACE_FUNNEL_DISINPUT_MASK, RVTRACE_FUNNEL_DISINPUT_OFFSET);
+ priv->disinput_mask = gtrace_read32(pdata, RVTRACE_FUNNEL_DISINPUT_OFFSET);
+ dev_set_drvdata(&comp->dev, priv);
+ return 0;
+}
+
+static const struct gtrace_component_id rvtrace_funnel_ids[] = {
+ { .type = GTRACE_RVTRACE_FUNNEL,
+ .version = rvtrace_component_mkversion(1, 0), },
+ {},
+};
+
+static struct gtrace_driver rvtrace_funnel_driver = {
+ .id_table = rvtrace_funnel_ids,
+ .start = rvtrace_funnel_start,
+ .stop = rvtrace_funnel_stop,
+ .start_port = rvtrace_funnel_start_port,
+ .stop_port = rvtrace_funnel_stop_port,
+ .probe = rvtrace_funnel_probe,
+ .driver = {
+ .name = "rvtrace-funnel",
+ },
+};
+
+static int __init rvtrace_funnel_init(void)
+{
+ return gtrace_register_driver(&rvtrace_funnel_driver);
+}
+
+static void __exit rvtrace_funnel_exit(void)
+{
+ gtrace_unregister_driver(&rvtrace_funnel_driver);
+}
+
+module_init(rvtrace_funnel_init);
+module_exit(rvtrace_funnel_exit);
+
+MODULE_AUTHOR("Zane Leung");
+MODULE_DESCRIPTION("RISC-V Trace Funnel Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hwtracing/gtrace/rvtrace-funnel.h b/drivers/hwtracing/gtrace/rvtrace-funnel.h
new file mode 100644
index 000000000000..41547c8971ba
--- /dev/null
+++ b/drivers/hwtracing/gtrace/rvtrace-funnel.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2026 Spacemit Technologies, Inc.
+ */
+
+#ifndef __RVTRACE_HENNEL_H__
+#define __RVTRACE_HENNEL_H__
+
+#define RVTRACE_FUNNEL_DISINPUT_OFFSET 0x008
+#define RVTRACE_FUNNEL_DISINPUT_MASK 0xffff
+
+/**
+ * struct rvtrace_encoder_priv - Private driver data for the rvtrace funnel
+ * @disinput_mask: Bitmask of inputs supporting disable.
+ */
+
+struct rvtrace_funnel_priv {
+ u32 disinput_mask;
+};
+
+#endif /* __RVTRACE_ENCODER_H__ */
diff --git a/drivers/hwtracing/gtrace/rvtrace-platform.c b/drivers/hwtracing/gtrace/rvtrace-platform.c
index 64496a638359..ad8daa06e13e 100644
--- a/drivers/hwtracing/gtrace/rvtrace-platform.c
+++ b/drivers/hwtracing/gtrace/rvtrace-platform.c
@@ -133,6 +133,9 @@ static int rvtrace_platform_probe(struct platform_device *pdev)
case GTRACE_RVTRACE_ENCODER:
pdata->groups = rvtrace_encoder_groups;
break;
+ case GTRACE_RVTRACE_FUNNEL:
+ pdata->groups = rvtrace_funnel_groups;
+ break;
default:
pdata->groups = NULL;
}
diff --git a/drivers/hwtracing/gtrace/rvtrace.h b/drivers/hwtracing/gtrace/rvtrace.h
index fee8e2e4f42a..a345ba110267 100644
--- a/drivers/hwtracing/gtrace/rvtrace.h
+++ b/drivers/hwtracing/gtrace/rvtrace.h
@@ -120,5 +120,6 @@ 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[];
#endif /* __LINUX_RVTRACE_H__ */
--
2.34.1
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