coresight: Add driver to support for dummy coresight device

Some Coresight devices that HLOS does not have permission to access
or configure. Such as Coresight sink EUD, some TPDMs etc.
So there needs driver to register dummy devices as Coresight devices.
Provide Coresight API for dummy devices operations, such as enable
and disable dummy devices.
Build the Coresight path for dummy sink or dummy source for debugging.

Change-Id: I93b24a84f0b463f92c5e5cb69b53a86bf873e7a6
Signed-off-by: Tao Zhang <taozha@codeaurora.org>
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>

drivers/hwtracing/coresight/Kconfig

@@ -188,6 +188,14 @@ config CORESIGHT_CTI_INTEGRATION_REGS
 	  registers are not used in normal operation and can leave devices in
 	  an inconsistent state.
 
+config CORESIGHT_DUMMY
+	tristate "Dummy driver support"
+	help
+	  Enables support for dummy driver. Dummy driver can be used for
+	  CoreSight sources/sinks that are owned and configured by some
+	  other subsystem and use Linux drivers to configure rest of trace
+	  path.
+
 config CORESIGHT_TRBE
 	tristate "Trace Buffer Extension (TRBE) driver"
 	depends on ARM64 && CORESIGHT_SOURCE_ETM4X

drivers/hwtracing/coresight/Makefile

@@ -27,3 +27,4 @@ obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
 obj-$(CONFIG_CORESIGHT_TRBE) += coresight-trbe.o
 coresight-cti-y := coresight-cti-core.o	coresight-cti-platform.o \
 		   coresight-cti-sysfs.o
+obj-$(CONFIG_CORESIGHT_DUMMY) += coresight-dummy.o

drivers/hwtracing/coresight/coresight-dummy.c

@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/coresight.h>
+#include <linux/of.h>
+#include <linux/pm_runtime.h>
+
+#define DUMMY_TRACE_ID_START	256
+
+struct dummy_drvdata {
+	struct device			*dev;
+	struct coresight_device		*csdev;
+	int				traceid;
+};
+
+DEFINE_CORESIGHT_DEVLIST(dummy_devs, "dummy");
+
+static int dummy_source_enable(struct coresight_device *csdev,
+			       struct perf_event *event, u32 mode)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy source enabled\n");
+
+	return 0;
+}
+
+static void dummy_source_disable(struct coresight_device *csdev,
+				 struct perf_event *event)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy source disabled\n");
+}
+
+static int dummy_sink_enable(struct coresight_device *csdev, u32 mode,
+				void *data)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy sink enabled\n");
+
+	return 0;
+}
+
+static int dummy_sink_disable(struct coresight_device *csdev)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	dev_info(drvdata->dev, "Dummy sink disabled\n");
+
+	return 0;
+}
+
+static int dummy_trace_id(struct coresight_device *csdev)
+{
+	struct dummy_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	return drvdata->traceid;
+}
+
+static const struct coresight_ops_source dummy_source_ops = {
+	.trace_id	= dummy_trace_id,
+	.enable		= dummy_source_enable,
+	.disable	= dummy_source_disable,
+};
+
+static const struct coresight_ops_sink dummy_sink_ops = {
+	.enable		= dummy_sink_enable,
+	.disable	= dummy_sink_disable,
+};
+
+static const struct coresight_ops dummy_cs_ops = {
+	.source_ops	= &dummy_source_ops,
+	.sink_ops	= &dummy_sink_ops,
+};
+
+static int dummy_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct coresight_platform_data *pdata;
+	struct dummy_drvdata *drvdata;
+	struct coresight_desc desc = { 0 };
+	static int traceid = DUMMY_TRACE_ID_START;
+
+	desc.name = coresight_alloc_device_name(&dummy_devs, dev);
+	if (!desc.name)
+		return -ENOMEM;
+	pdata = coresight_get_platform_data(dev);
+	if (IS_ERR(pdata))
+		return PTR_ERR(pdata);
+	pdev->dev.platform_data = pdata;
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	drvdata->dev = &pdev->dev;
+	platform_set_drvdata(pdev, drvdata);
+
+	drvdata->traceid = traceid++;
+
+	if (of_property_read_bool(pdev->dev.of_node, "qcom,dummy-source")) {
+		desc.type = CORESIGHT_DEV_TYPE_SOURCE;
+		desc.subtype.source_subtype =
+					CORESIGHT_DEV_SUBTYPE_SOURCE_PROC;
+	} else if (of_property_read_bool(pdev->dev.of_node,
+					 "qcom,dummy-sink")) {
+		desc.type = CORESIGHT_DEV_TYPE_SINK;
+		desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
+	} else {
+		dev_info(dev, "Device type not set\n");
+		return -EINVAL;
+	}
+
+	desc.ops = &dummy_cs_ops;
+	desc.pdata = pdev->dev.platform_data;
+	desc.dev = &pdev->dev;
+	drvdata->csdev = coresight_register(&desc);
+	if (IS_ERR(drvdata->csdev))
+		return PTR_ERR(drvdata->csdev);
+
+	pm_runtime_enable(dev);
+	dev_info(dev, "Dummy device initialized\n");
+
+	return 0;
+}
+
+static int dummy_remove(struct platform_device *pdev)
+{
+	struct dummy_drvdata *drvdata = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	pm_runtime_disable(dev);
+	coresight_unregister(drvdata->csdev);
+	return 0;
+}
+
+static const struct of_device_id dummy_match[] = {
+	{.compatible = "qcom,coresight-dummy"},
+	{},
+};
+
+static struct platform_driver dummy_driver = {
+	.probe	= dummy_probe,
+	.remove	= dummy_remove,
+	.driver	= {
+		.name   = "coresight-dummy",
+		.of_match_table = dummy_match,
+	},
+};
+
+int __init dummy_init(void)
+{
+	return platform_driver_register(&dummy_driver);
+}
+module_init(dummy_init);
+
+void __exit dummy_exit(void)
+{
+	platform_driver_unregister(&dummy_driver);
+}
+module_exit(dummy_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CoreSight dummy source driver");