[PATCH v5 06/14] gtrace: Add RISC-V Trace encoder driver

[Mayuresh Chitale]

Add initial implementation of RISC-V E-Trace encoder driver. The encoder
is defined in the RISC-V Trace Control Interface specification.

Co-developed-by: Anup Patel <anup.patel at oss.qualcomm.com>
Signed-off-by: Anup Patel <anup.patel at oss.qualcomm.com>
Signed-off-by: Mayuresh Chitale <mayuresh.chitale at oss.qualcomm.com>
---
 drivers/hwtracing/gtrace/Kconfig           | 13 +++
 drivers/hwtracing/gtrace/Makefile          |  1 +
 drivers/hwtracing/gtrace/rvtrace-encoder.c | 99 ++++++++++++++++++++++
 3 files changed, 113 insertions(+)
 create mode 100644 drivers/hwtracing/gtrace/rvtrace-encoder.c

diff --git a/drivers/hwtracing/gtrace/Kconfig b/drivers/hwtracing/gtrace/Kconfig
index 04986f216549..e3a621b59913 100644
--- a/drivers/hwtracing/gtrace/Kconfig
+++ b/drivers/hwtracing/gtrace/Kconfig
@@ -28,3 +28,16 @@ config RVTRACE
 
 	  To compile this driver as a module, choose M here: the module
 	  will be called rvtrace.
+
+config RVTRACE_ENCODER
+	tristate "RISC-V Trace Encoder driver"
+	depends on RVTRACE
+	default y
+	help
+	  This driver provides support for the RISC-V trace encoder component
+	  which is defined by the RISC-V Trace Control Interface specification.
+	  The encoder is bound to a CPU and generates the trace data for that
+	  CPU.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called rvtrace-encoder.
diff --git a/drivers/hwtracing/gtrace/Makefile b/drivers/hwtracing/gtrace/Makefile
index cf02316c1bbf..10a74f852115 100644
--- a/drivers/hwtracing/gtrace/Makefile
+++ b/drivers/hwtracing/gtrace/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_GTRACE) += gtrace.o
 gtrace-y := gtrace-core.o
 
 obj-$(CONFIG_RVTRACE) += rvtrace-platform.o
+obj-$(CONFIG_RVTRACE_ENCODER) += rvtrace-encoder.o
diff --git a/drivers/hwtracing/gtrace/rvtrace-encoder.c b/drivers/hwtracing/gtrace/rvtrace-encoder.c
new file mode 100644
index 000000000000..9ff3413d1aa4
--- /dev/null
+++ b/drivers/hwtracing/gtrace/rvtrace-encoder.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026 Qualcomm Technologies, Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/gtrace.h>
+#include <linux/types.h>
+#include "rvtrace.h"
+
+#define RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT	2
+#define RVTRACE_COMPONENT_CTRL_INSTMODE_SHIFT	4
+#define RVTRACE_COMPONENT_CTRL_INSTMODE_OPIT	0x6
+
+static int rvtrace_encoder_start(struct gtrace_component *comp)
+{
+	struct gtrace_platform_data *pdata = comp->pdata;
+	int ret;
+	u32 val;
+
+	ret = gtrace_enable_component(comp);
+	if (ret) {
+		dev_err(&comp->dev, "failed to enable encoder.\n");
+		return ret;
+	}
+
+	/* set mode */
+	val = gtrace_read32(pdata, RVTRACE_COMPONENT_CTRL_OFFSET);
+	val |= (RVTRACE_COMPONENT_CTRL_INSTMODE_OPIT << RVTRACE_COMPONENT_CTRL_INSTMODE_SHIFT);
+	gtrace_write32(pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET);
+
+	val = gtrace_read32(pdata, RVTRACE_COMPONENT_CTRL_OFFSET);
+	val |= BIT(RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT);
+	gtrace_write32(pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET);
+	ret = gtrace_poll_bit(pdata, RVTRACE_COMPONENT_CTRL_OFFSET,
+			      RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT, 1,
+			      pdata->control_poll_timeout_usecs);
+	if (ret)
+		dev_err(&comp->dev, "failed to enable tracing.\n");
+
+	return ret;
+}
+
+static int rvtrace_encoder_stop(struct gtrace_component *comp)
+{
+	struct gtrace_platform_data *pdata = comp->pdata;
+	int ret;
+	u32 val;
+
+	val = gtrace_read32(pdata, RVTRACE_COMPONENT_CTRL_OFFSET);
+	val &= ~BIT(RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT);
+	gtrace_write32(pdata, val, RVTRACE_COMPONENT_CTRL_OFFSET);
+	ret = gtrace_poll_bit(pdata, RVTRACE_COMPONENT_CTRL_OFFSET,
+			      RVTRACE_COMPONENT_CTRL_ITRACE_SHIFT, 0,
+			      pdata->control_poll_timeout_usecs);
+	if (ret) {
+		dev_err(&comp->dev, "failed to stop tracing.\n");
+		return ret;
+	}
+
+	ret = gtrace_disable_component(comp);
+	if (ret)
+		dev_err(&comp->dev, "failed to disable encoder.\n");
+
+	return ret;
+}
+
+static const struct gtrace_component_id rvtrace_encoder_ids[] = {
+	{ .type = GTRACE_RVTRACE_ENCODER,
+	  .version = rvtrace_component_mkversion(1, 0), },
+	{},
+};
+
+static struct gtrace_driver rvtrace_encoder_driver = {
+	.id_table = rvtrace_encoder_ids,
+	.start = rvtrace_encoder_start,
+	.stop = rvtrace_encoder_stop,
+	.driver = {
+		.name = "rvtrace-encoder",
+	},
+};
+
+static int __init rvtrace_encoder_init(void)
+{
+	return gtrace_register_driver(&rvtrace_encoder_driver);
+}
+
+static void __exit rvtrace_encoder_exit(void)
+{
+	gtrace_unregister_driver(&rvtrace_encoder_driver);
+}
+
+module_init(rvtrace_encoder_init);
+module_exit(rvtrace_encoder_exit);
+
+/* Module information */
+MODULE_AUTHOR("Mayuresh Chitale");
+MODULE_DESCRIPTION("RISC-V Trace Encoder Driver");
+MODULE_LICENSE("GPL");
-- 
2.43.0