[PATCH v4 1/3] Coresight: Add coresight dummy driver

[Hao Zhang]

Hi Suzuki,

On 5/5/2023 5:57 PM, Suzuki K Poulose wrote:
> On 05/05/2023 10:24, Hao Zhang wrote:
>> Some Coresight devices that kernel don't have permission to access or
>> configure. So there need driver to register dummy devices as Coresight
>> devices. It may also be used to define components that may not have
>> any programming interfaces (e.g, static links), so that paths can be
>> established in the driver. 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 at quicinc.com>
>> ---
>>   drivers/hwtracing/coresight/Kconfig           |  11 ++
>>   drivers/hwtracing/coresight/Makefile          |   1 +
>>   drivers/hwtracing/coresight/coresight-dummy.c | 171 ++++++++++++++++++
>>   include/linux/coresight.h                     |   1 +
>>   4 files changed, 184 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..ee9881ff4754
>> --- /dev/null
>> +++ b/drivers/hwtracing/coresight/coresight-dummy.c
>> @@ -0,0 +1,171 @@
>> +// 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>
> 
> Please follow the alphabetical order for the header files ^
> 
Sure, I will update this in the next patch series.

>> +
>> +#include "coresight-priv.h"
>> +
>> +struct dummy_drvdata {
>> +    struct device            *dev;
> 
> nit: We don't need this really. And that completely removes the need for
> drvdata too. See below.
> 
>> +    struct coresight_device        *csdev;
>> +};
>> +
>> +DEFINE_CORESIGHT_DEVLIST(source_devs, "dummy_source");
>> +DEFINE_CORESIGHT_DEVLIST(sink_devs, "dummy_sink");
>> +
>> +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_dbg(drvdata->dev, "Dummy source enabled\n");
> 
>      dev_dbg(csdev->dev.parent, ..");
> 
> Similarly for all instances below.
> 
>> +
>> +    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_dbg(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_dbg(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_dbg(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 dummy_source_cs_ops = {
>> +    .source_ops = &dummy_source_ops,
>> +};
>> +
>> +static const struct coresight_ops_sink dummy_sink_ops = {
>> +    .enable    = dummy_sink_enable,
>> +    .disable = dummy_sink_disable,
>> +};
>> +
>> +static const struct coresight_ops dummy_sink_cs_ops = {
>> +    .sink_ops = &dummy_sink_ops,
>> +};
>> +
>> +static int dummy_probe(struct platform_device *pdev)
>> +{
>> +    struct device *dev = &pdev->dev;
>> +    struct device_node *node = dev->of_node;
>> +    struct coresight_platform_data *pdata;
>> +    struct dummy_drvdata *drvdata;
>> +    struct coresight_desc desc = { 0 };
>> +
>> +    if (of_device_is_compatible(node, "arm,coresight-dummy-source")) {
>> +
>> +        desc.name = coresight_alloc_device_name(&source_devs, dev);
>> +        if (!desc.name)
>> +            return -ENOMEM;
>> +
>> +        desc.type = CORESIGHT_DEV_TYPE_SOURCE;
>> +        desc.subtype.source_subtype =
>> +                    CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS;
>> +        desc.ops = &dummy_source_cs_ops;
>> +    } else if (of_device_is_compatible(node, 
>> "arm,coresight-dummy-sink")) {
>> +        desc.name = coresight_alloc_device_name(&sink_devs, dev);
>> +        if (!desc.name)
>> +            return -ENOMEM;
>> +
>> +        desc.type = CORESIGHT_DEV_TYPE_SINK;
>> +        desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_DUMMY;
>> +        desc.ops = &dummy_sink_cs_ops;
>> +    } else {
>> +        dev_err(dev, "Device type not set\n");
>> +        return -EINVAL;
>> +    }
>> +
>> +    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);
> 
> As above, you may remove the drvdata entirely.
> 
For some dummy sources, it's needed to allocate traceid for them in 
kernel driver, so this struct would be useful for that case.

I will remove it now and upstream it in the further.

Thanks,
Hao

> Otherwise looks good to me
> 
> Suzuki
>