[PATCH 10/24] gtrace: Add RISC-V trace funnel driver

[Zane Leung]

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@xxxxxxxxxxxxxxxxxx>
---
 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