Hi,

On Fri, 24 Mar 2023 at 06:16, Hao Zhang quic_hazha@quicinc.com wrote:

Some Coresight devices that HLOS don't have permission to access or configure. Such as Coresight sink EUD, some TPDMs etc. So there need driver to register dummy devices as Coresight devices. Provide Coresight API for dummy device operations, such as enabling and disabling dummy devices. Build the Coresight path for dummy sink or dummy source for debugging.

Signed-off-by: Hao Zhang quic_hazha@quicinc.com

drivers/hwtracing/coresight/Kconfig | 11 ++ drivers/hwtracing/coresight/Makefile | 1 + drivers/hwtracing/coresight/coresight-dummy.c | 176 ++++++++++++++++++ 3 files changed, 188 insertions(+) create mode 100644 drivers/hwtracing/coresight/coresight-dummy.c

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig index 2b5bbfffbc4f..06f0a7594169 100644 --- a/drivers/hwtracing/coresight/Kconfig +++ b/drivers/hwtracing/coresight/Kconfig @@ -236,4 +236,15 @@ config CORESIGHT_TPDA

      To compile this driver as a module, choose M here: the module will be
      called coresight-tpda.

+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.
  

•     To compile this driver as a module, choose M here: the module will be
  

•     called coresight-dummy.
  

endif diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile index 33bcc3f7b8ae..995d3b2c76df 100644 --- a/drivers/hwtracing/coresight/Makefile +++ b/drivers/hwtracing/coresight/Makefile @@ -30,3 +30,4 @@ obj-$(CONFIG_CORESIGHT_TPDA) += coresight-tpda.o coresight-cti-y := coresight-cti-core.o coresight-cti-platform.o \ coresight-cti-sysfs.o obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc-smb.o +obj-$(CONFIG_CORESIGHT_DUMMY) += coresight-dummy.o diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/hwtracing/coresight/coresight-dummy.c new file mode 100644 index 000000000000..2d4eb3e546eb --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-dummy.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (c) 2023 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>

+#include "coresight-priv.h" +#include "coresight-trace-id.h"

+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 const struct coresight_ops_source dummy_source_ops = {

•   .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) +{

•   int ret, trace_id;
  

•   struct device *dev = &pdev->dev;
  

•   struct coresight_platform_data *pdata;
  

•   struct dummy_drvdata *drvdata;
  

•   struct coresight_desc desc = { 0 };
  

•   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);
  

•   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_OTHERS;
  

•   } 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;
  

This will break the automatic sink selection on a system where perf is looking for a default sink and the dummy sink is closest / first discovered.

i.e. when perf record -e cs_etm// <options> is used to trace a program in linux, a dummy sink appearing in the coresight tree with this designation may be selected.

This needs to be corrected, probably with a unique sub-type that appears before the CORESIGHT_DEV_SUBTYPE_SINK_BUFFER value in the enum as the selection is based on >= CORESIGHT_DEV_SUBTYPE_SINK_BUFFER.

By implication adding a new value - will possibly affect other code using the enum values so will need to be checked

Regards

Mike

•   } 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);
  

•   trace_id = coresight_trace_id_get_system_id();
  

•   if (trace_id < 0) {
  

•           ret = trace_id;
  

•           goto cs_unregister;
  

•   }
  

•   drvdata->traceid = (u8)trace_id;
  

•   pm_runtime_enable(dev);
  

•   dev_info(dev, "Dummy device initialized\n");
  

•   return 0;
  

+cs_unregister:

•   coresight_unregister(drvdata->csdev);
  

•   return ret;
  

+}

+static int dummy_remove(struct platform_device *pdev) +{

•   struct dummy_drvdata *drvdata = platform_get_drvdata(pdev);
  

•   struct device *dev = &pdev->dev;
  

•   coresight_trace_id_put_system_id(drvdata->traceid);
  

•   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,
  

•   },
  

+};

+static int __init dummy_init(void) +{

•   return platform_driver_register(&dummy_driver);
  

+} +module_init(dummy_init);

+static void __exit dummy_exit(void) +{

•   platform_driver_unregister(&dummy_driver);
  

+} +module_exit(dummy_exit);

+MODULE_LICENSE("GPL");

+MODULE_DESCRIPTION("CoreSight dummy source driver");

2.17.1