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Message-ID: <6ca3de6d-eaba-f9c1-1809-90902a69564a@arm.com>
Date: Mon, 24 Apr 2023 13:09:54 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Hao Zhang <quic_hazha@...cinc.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
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
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