Hi,
On Fri, 24 Mar 2023 at 06:16, Hao Zhang <quic_hazha@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> ---
> 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
>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
