Re: [PATCH v2 2/5] coresight: add coresight Trace NOC driver

Leo Yan
2025-02-27T12:10:43Z

Hi Yuanfang,

On Wed, Feb 26, 2025 at 07:05:51PM +0800, Yuanfang Zhang wrote:
>
> Add driver to support Coresight device Trace NOC(Network On Chip).
> Trace NOC is an integration hierarchy which is a replacement of
> Dragonlink configuration. It brings together debug components like
> TPDA, funnel and interconnect Trace Noc.
>
> It sits in the different subsystem of SOC and aggregates the trace
> and transports to QDSS trace bus.
>
> Signed-off-by: Yuanfang Zhang <quic_yuanfang@quicinc.com>
> ---
> drivers/hwtracing/coresight/Kconfig | 13 ++
> drivers/hwtracing/coresight/Makefile | 1 +
> drivers/hwtracing/coresight/coresight-tnoc.c | 190 +++++++++++++++++++++++++++
> drivers/hwtracing/coresight/coresight-tnoc.h | 53 ++++++++
> 4 files changed, 257 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 06f0a7594169c5f03ca5f893b7debd294587de78..6cfd160f09d383ab5f5aa276fa57496a52c8f961 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -247,4 +247,17 @@ config CORESIGHT_DUMMY
>
> To compile this driver as a module, choose M here: the module will be
> called coresight-dummy.
> +
> +config CORESIGHT_TNOC
> + tristate "Coresight Trace Noc driver"
> + help
> + This driver provides support for Trace NoC component.
> + Trace NoC is a interconnect that is used to collect trace from
> + various subsystems and transport it QDSS trace sink.It sits in

Trace NoC is an interconnect used to collect traces from various
subsystems and transport to a QDSS trace sink.

> + the different tiles of SOC and aggregates the trace local to the
> + tile and transports it another tile or to QDSS trace sink eventually.
> +
> + To compile this driver as a module, choose M here: the module will be
> + called coresight-tnoc.
> +
> endif
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 4ba478211b318ea5305f9f98dda40a041759f09f..60b729979f19c8f8848c77c290605132dba1a991 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_CORESIGHT_SINK_TPIU) += coresight-tpiu.o
> obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
> obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
> coresight-replicator.o
> +obj-$(CONFIG_CORESIGHT_TNOC) += coresight-tnoc.o
> obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
> coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
> coresight-etm3x-sysfs.o
> diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..fad8e61f05ef25989aba1be342c547f835e8953a
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-tnoc.c
> @@ -0,0 +1,190 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/amba/bus.h>
> +#include <linux/io.h>
> +#include <linux/coresight.h>
> +#include <linux/of.h>

Please include headers in alphabetical ordering.

> +#include "coresight-priv.h"
> +#include "coresight-tnoc.h"
> +#include "coresight-trace-id.h"
> +
> +static void trace_noc_enable_hw(struct trace_noc_drvdata *drvdata)
> +{
> + u32 val;
> +
> + /* Set ATID */
> + writel_relaxed(drvdata->atid, drvdata->base + TRACE_NOC_XLD);
> +
> + /* Config sync CR */
> + writel_relaxed(0xffff, drvdata->base + TRACE_NOC_SYNCR);
> +
> + /* Set frequency value */
> + writel_relaxed(drvdata->freq_req_val, drvdata->base + TRACE_NOC_FREQVAL);
> +
> + /* Set Ctrl register */
> + val = readl_relaxed(drvdata->base + TRACE_NOC_CTRL);
> +
> + if (drvdata->flag_type == FLAG_TS)
> + val = val | TRACE_NOC_CTRL_FLAGTYPE;
> + else
> + val = val & ~TRACE_NOC_CTRL_FLAGTYPE;
> +
> + if (drvdata->freq_type == FREQ_TS)
> + val = val | TRACE_NOC_CTRL_FREQTYPE;
> + else
> + val = val & ~TRACE_NOC_CTRL_FREQTYPE;
> +
> + val = val | TRACE_NOC_CTRL_PORTEN;
> + writel_relaxed(val, drvdata->base + TRACE_NOC_CTRL);

It is fine for using writel_relaxed() for continuous writing into the
same component. However, the last writing into TRACE_NOC_CTRL enales
the NOC but without any barrier guard, it might cause the out-of-order
issue with Arm CoreSight modules (or any other relevant endpoints).

I'd like suggest to use writel() for writing TRACE_NOC_CTRL.

> + dev_dbg(drvdata->dev, "Trace NOC is enabled\n");
> +}
> +
> +static int trace_noc_enable(struct coresight_device *csdev, struct coresight_connection *inport,
> + struct coresight_connection *outport)
> +{
> + struct trace_noc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +
> + spin_lock(&drvdata->spinlock);
> + if (csdev->refcnt == 0)

AFAICT csdev->refcnt is only used in sink drivers. This driver is for
funnel, it should use `inport->dest_refcnt` as the counter.

> + trace_noc_enable_hw(drvdata);
> +
> + csdev->refcnt++;
> + spin_unlock(&drvdata->spinlock);
> +
> + return 0;
> +}
> +
> +static void trace_noc_disable_hw(struct trace_noc_drvdata *drvdata)
> +{
> + writel_relaxed(0x0, drvdata->base + TRACE_NOC_CTRL);

Same with the comment above for using writel() to replace
writel_relaxed().

> + dev_dbg(drvdata->dev, "Trace NOC is disabled\n");
> +}
> +
> +static void trace_noc_disable(struct coresight_device *csdev, struct coresight_connection *inport,
> + struct coresight_connection *outport)
> +{
> + struct trace_noc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +
> + spin_lock(&drvdata->spinlock);
> + if (--csdev->refcnt == 0)
> + trace_noc_disable_hw(drvdata);
> +
> + spin_unlock(&drvdata->spinlock);
> + dev_info(drvdata->dev, "Trace NOC is disabled\n");
> +}
> +
> +static const struct coresight_ops_link trace_noc_link_ops = {
> + .enable = trace_noc_enable,
> + .disable = trace_noc_disable,
> +};
> +
> +static const struct coresight_ops trace_noc_cs_ops = {
> + .link_ops = &trace_noc_link_ops,
> +};
> +
> +static int trace_noc_init_default_data(struct trace_noc_drvdata *drvdata)
> +{
> + int atid;
> +
> + atid = coresight_trace_id_get_system_id();
> + if (atid < 0)
> + return atid;
> +
> + drvdata->atid = atid;
> +
> + drvdata->freq_type = FREQ_TS;

I don't see anywhere uses FREQ. Please remove the unused definitions
and related code.

> + drvdata->flag_type = FLAG;

FLAG_TS is not used in the driver as well. Remove it.

> + drvdata->freq_req_val = 0;
> +
> + return 0;
> +}
> +
> +static int trace_noc_probe(struct amba_device *adev, const struct amba_id *id)
> +{
> + struct device *dev = &adev->dev;
> + struct coresight_platform_data *pdata;
> + struct trace_noc_drvdata *drvdata;
> + struct coresight_desc desc = { 0 };
> + int ret;
> +
> + desc.name = coresight_alloc_device_name(&trace_noc_devs, dev);
> + if (!desc.name)
> + return -ENOMEM;
> + pdata = coresight_get_platform_data(dev);
> + if (IS_ERR(pdata))
> + return PTR_ERR(pdata);
> + adev->dev.platform_data = pdata;
> +
> + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> + if (!drvdata)
> + return -ENOMEM;
> +
> + drvdata->dev = &adev->dev;
> + dev_set_drvdata(dev, drvdata);
> +
> + drvdata->base = devm_ioremap_resource(dev, &adev->res);
> + if (!drvdata->base)
> + return -ENOMEM;
> +
> + spin_lock_init(&drvdata->spinlock);
> +
> + ret = trace_noc_init_default_data(drvdata);
> + if (ret)
> + return ret;
> +
> + desc.ops = &trace_noc_cs_ops;
> + desc.type = CORESIGHT_DEV_TYPE_LINK;
> + desc.subtype.link_subtype = CORESIGHT_DEV_SUBTYPE_LINK_MERG;
> + desc.pdata = adev->dev.platform_data;
> + desc.dev = &adev->dev;
> + desc.access = CSDEV_ACCESS_IOMEM(drvdata->base);
> + drvdata->csdev = coresight_register(&desc);
> + if (IS_ERR(drvdata->csdev))
> + return PTR_ERR(drvdata->csdev);
> +
> + pm_runtime_put(&adev->dev);
> +
> + return 0;
> +}
> +
> +static void trace_noc_remove(struct amba_device *adev)
> +{
> + struct trace_noc_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> +
> + coresight_trace_id_put_system_id(drvdata->atid);
> + coresight_unregister(drvdata->csdev);
> +}
> +
> +static struct amba_id trace_noc_ids[] = {
> + {
> + .id = 0x000f0c00,
> + .mask = 0x000fff00,

Unlike Arm CoreSight drivers (the mask value is 0x000fffff in most
cases), could you remind me why here the mask is 0x000fff00?

> + },
> + {},
> +};
> +MODULE_DEVICE_TABLE(amba, trace_noc_ids);
> +
> +static struct amba_driver trace_noc_driver = {
> + .drv = {
> + .name = "coresight-trace-noc",
> + .owner = THIS_MODULE,

I don't think you need to explicitly set `THIS_MODULE`, as this will
be set default by amba_driver_register().

> + .suppress_bind_attrs = true,
> + },
> + .probe = trace_noc_probe,
> + .remove = trace_noc_remove,
> + .id_table = trace_noc_ids,
> +};
> +
> +module_amba_driver(trace_noc_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Trace NOC driver");
> diff --git a/drivers/hwtracing/coresight/coresight-tnoc.h b/drivers/hwtracing/coresight/coresight-tnoc.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..b6bd1ef659897d8e0994c5e8514e8cbdd16eebd8
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-tnoc.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#define TRACE_NOC_CTRL 0x008
> +#define TRACE_NOC_XLD 0x010
> +#define TRACE_NOC_FREQVAL 0x018
> +#define TRACE_NOC_SYNCR 0x020
> +
> +/* Enable generation of output ATB traffic.*/
> +#define TRACE_NOC_CTRL_PORTEN BIT(0)
> +/* Writing 1 to issue a FREQ or FREQ_TS packet*/
> +#define TRACE_NOC_CTRL_FREQTSREQ BIT(5)

This is not used. Remove it.

> +/* Sets the type of issued ATB FLAG packets. 0: 'FLAG' packets; 1: 'FLAG_TS' packets.*/
> +#define TRACE_NOC_CTRL_FLAGTYPE BIT(7)

> +/* sets the type of issued ATB FREQ packets. 0: 'FREQ' packets; 1: 'FREQ_TS' packets.*/
> +#define TRACE_NOC_CTRL_FREQTYPE BIT(8)
> +DEFINE_CORESIGHT_DEVLIST(trace_noc_devs, "traceNoc");

It is good to move the definition into C file.

Thanks,
Leo

> +
> +/**
> + * struct trace_noc_drvdata - specifics associated to a trace noc component
> + * @base: memory mapped base address for this component.
> + * @dev: device node for trace_noc_drvdata.
> + * @csdev: component vitals needed by the framework.
> + * @spinlock: only one at a time pls.
> + * @atid: id for the trace packet.
> + * @freqtype: 0: 'FREQ' packets; 1: 'FREQ_TS' packets.
> + * @flagtype: 0: 'FLAG' packets; 1: 'FLAG_TS' packets.
> + * @freq_req_val: set frequency values carried by 'FREQ' and 'FREQ_TS' packets.
> + */
> +struct trace_noc_drvdata {
> + void __iomem *base;
> + struct device *dev;
> + struct coresight_device *csdev;
> + spinlock_t spinlock; /* lock for the drvdata. */
> + u32 atid;
> + u32 freq_type;
> + u32 flag_type;
> + u32 freq_req_val;
> +};
> +
> +/* freq type */
> +enum freq_type {
> + FREQ,
> + FREQ_TS,
> +};
> +
> +/* flag type */
> +enum flag_type {
> + FLAG,
> + FLAG_TS,
> +};
>
> --
> 2.34.1
>
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