Messages in this thread | | | Date | Tue, 28 Mar 2023 09:35:55 +0100 | Subject | Re: [PATCH v2 1/3] Coresight: Add coresight dummy driver | From | Suzuki K Poulose <> |
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On 28/03/2023 08:22, Hao Zhang wrote: > Hi Mike, > > On 3/27/2023 11:58 PM, Mike Leach wrote: >> 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. >>
Good point Mike.
>> By implication adding a new value - will possibly affect other code >> using the enum values so will need to be checked >> >> Regards >> >> Mike >> > > Thanks for your comments, I will add a new sub-type for dummy sink and > check the impact of it.
Please keep this as the lowest priority, something like:
enum coresight_dev_subtype_sink { + CORESIGHT_DEV_SUBTYPE_SINK_DUMMY, CORESIGHT_DEV_SUBTYPE_SINK_PORT, CORESIGHT_DEV_SUBTYPE_SINK_BUFFER, CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM, CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM, };
This should be fine without any impact on the existing code, as we expect the driver modules to be updated with the new core module.
Suzuki
> > Thanks, > Hao > >> >>> + } 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 >>> >> >>
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