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Message-ID: <d0be9671-bb32-e306-0a0f-c706837df994@quicinc.com>
Date: Fri, 28 Apr 2023 13:35:50 +0800
From: Hao Zhang <quic_hazha@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Konrad Dybcio <konradybcio@...il.com>,
"Rob Herring" <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Andy Gross <agross@...nel.org>,
"Paul Walmsley" <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Jonathan Corbet <corbet@....net>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
<coresight@...ts.linaro.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
Tingwei Zhang <quic_tingweiz@...cinc.com>,
Jinlong Mao <quic_jinlmao@...cinc.com>,
"Yuanfang Zhang" <quic_yuanfang@...cinc.com>,
Tao Zhang <quic_taozha@...cinc.com>,
Trilok Soni <quic_tsoni@...cinc.com>,
<linux-arm-msm@...r.kernel.org>,
"Bjorn Andersson" <andersson@...nel.org>,
<linux-doc@...r.kernel.org>
Subject: Re: [PATCH v3 1/3] Coresight: Add coresight dummy driver
Hi Suzuki,
On 4/24/2023 8:09 PM, Suzuki K Poulose wrote:
> On 22/04/2023 08:37, 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@...cinc.com>
>> ---
>> drivers/hwtracing/coresight/Kconfig | 11 ++
>> drivers/hwtracing/coresight/Makefile | 1 +
>> drivers/hwtracing/coresight/coresight-dummy.c | 179 ++++++++++++++++++
>> include/linux/coresight.h | 1 +
>> 4 files changed, 192 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..1fb8b3d1c170
>> --- /dev/null
>> +++ b/drivers/hwtracing/coresight/coresight-dummy.c
>> @@ -0,0 +1,179 @@
>> +// 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(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");
>> +
>> + 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)
>> +{
>> + int trace_id;
>> + 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")) {
>> + trace_id = coresight_trace_id_get_system_id();
>
> Why is this needed ? If at all we need something, this must be
> explicitly asked for. How is this used ?
> >
>> + if (trace_id < 0)
>> + return trace_id;
>> +
>> + 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;
>
> If we have allocated a traceid, we must clean it up here and/or at
> device removal.
> >> +
>> + drvdata->dev = &pdev->dev;
>> + platform_set_drvdata(pdev, drvdata);
>> +
>> + 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);
>> +
>> + drvdata->traceid = (u8)trace_id;
>
> Where/how is this used ?
>
> Suzuki
>
This is required for ATID filtering funtion which is our HW design for
ETR, we need to set traceid/atid for etm, stm and tpda. Therefore, it's
needed if the type of dummy source is etm. This part is waiting for
upstream. I will remove it now and upstream it as the part of ATID
filtering in the further.
Thanks,
Hao
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