Re: [PATCH v14 02/10] Coresight: Add trace_id function to retrieving the trace ID

[Jie Gan <quic_jiegan@xxxxxxxxxxx>]

On 2/26/2025 7:55 PM, Suzuki K Poulose wrote:
> On 26/02/2025 04:13, Jie Gan wrote:
> > Add 'trace_id' function pointer in coresight_ops. It's responsible for 
> > retrieving
> > the device's trace ID.
> >
> > Co-developed-by: James Clark <james.clark@xxxxxxxxxx>
> > Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
> > Reviewed-by: James Clark <james.clark@xxxxxxxxxx>
> > Signed-off-by: Jie Gan <quic_jiegan@xxxxxxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-core.c  | 27 +++++++++++++++++++
> >   drivers/hwtracing/coresight/coresight-dummy.c | 13 ++++++++-
> >   .../coresight/coresight-etm3x-core.c          |  1 +
> >   .../coresight/coresight-etm4x-core.c          |  1 +
> >   drivers/hwtracing/coresight/coresight-stm.c   | 11 ++++++++
> >   drivers/hwtracing/coresight/coresight-tpda.c  | 11 ++++++++
> >   include/linux/coresight.h                     |  5 ++++
> >   7 files changed, 68 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/ 
> > hwtracing/coresight/coresight-core.c
> > index 0a9380350fb5..6cad777757f3 100644
> > --- a/drivers/hwtracing/coresight/coresight-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > @@ -23,6 +23,7 @@
> >   #include "coresight-etm-perf.h"
> >   #include "coresight-priv.h"
> >   #include "coresight-syscfg.h"
> > +#include "coresight-trace-id.h"
> >   /*
> >    * Mutex used to lock all sysfs enable and disable actions and 
> > loading and
> > @@ -1515,6 +1516,32 @@ void coresight_remove_driver(struct amba_driver 
> > *amba_drv,
> >   }
> >   EXPORT_SYMBOL_GPL(coresight_remove_driver);
> > +int coresight_etm_get_trace_id(struct coresight_device *csdev, enum 
> > cs_mode mode,
> > +                   struct coresight_device *sink)
> > +{
> > +    int trace_id;
> > +    int cpu = source_ops(csdev)->cpu_id(csdev);
> > +
> > +    switch (mode) {
> > +    case CS_MODE_SYSFS:
> > +        trace_id = coresight_trace_id_get_cpu_id(cpu);
> > +        break;
> > +    case CS_MODE_PERF:
>
> Please could we handle a case where "sink" may be passed NULL ?
>
>          if (WARN_ON(!sink))
>              return -EINVAL;
>
> Sorry, didn't spot that in the last review.

Hi Suzuki,

Thanks for poniting out.

There are two scenarios for current useage:
1. From traceid_show() - this is sysfs mode, so we dont need check sink.
2. From coresight_path_assign_trace_id function, the sink is obtained 
from coresight_path and the "sink" has been verified before building the 
coresight_path.

That's why I did not include the verification for sink before using it.
But I think it's worthwhile to add this code to enhance our code's 
robustness.

Will fix it in next version.

Thanks,
Jie

> Suzuki
>
>
> > +        trace_id = coresight_trace_id_get_cpu_id_map(cpu, &sink- 
> > >perf_sink_id_map);
>
> > +        break;
> > +    default:
> > +        trace_id = -EINVAL;
> > +        break;
> > +    }
> > +
> > +    if (!IS_VALID_CS_TRACE_ID(trace_id))
> > +        dev_err(&csdev->dev,
> > +            "Failed to allocate trace ID on CPU%d\n", cpu);
> > +
> > +    return trace_id;
> > +}
> > +EXPORT_SYMBOL_GPL(coresight_etm_get_trace_id);
> > +
> >   MODULE_LICENSE("GPL v2");
> >   MODULE_AUTHOR("Pratik Patel <pratikp@xxxxxxxxxxxxxx>");
> >   MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>");
> > diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/ 
> > hwtracing/coresight/coresight-dummy.c
> > index 9be53be8964b..b5692ba358c1 100644
> > --- a/drivers/hwtracing/coresight/coresight-dummy.c
> > +++ b/drivers/hwtracing/coresight/coresight-dummy.c
> > @@ -41,6 +41,16 @@ static void dummy_source_disable(struct 
> > coresight_device *csdev,
> >       dev_dbg(csdev->dev.parent, "Dummy source disabled\n");
> >   }
> > +static int dummy_source_trace_id(struct coresight_device *csdev, 
> > __maybe_unused enum cs_mode mode,
> > +                 __maybe_unused struct coresight_device *sink)
> > +{
> > +    struct dummy_drvdata *drvdata;
> > +
> > +    drvdata = dev_get_drvdata(csdev->dev.parent);
> > +
> > +    return drvdata->traceid;
> > +}
> > +
> >   static int dummy_sink_enable(struct coresight_device *csdev, enum 
> > cs_mode mode,
> >                   void *data)
> >   {
> > @@ -62,7 +72,8 @@ static const struct coresight_ops_source 
> > dummy_source_ops = {
> >   };
> >   static const struct coresight_ops dummy_source_cs_ops = {
> > -    .source_ops = &dummy_source_ops,
> > +    .trace_id    = dummy_source_trace_id,
> > +    .source_ops    = &dummy_source_ops,
> >   };
> >   static const struct coresight_ops_sink dummy_sink_ops = {
> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/ 
> > drivers/hwtracing/coresight/coresight-etm3x-core.c
> > index c103f4c70f5d..c1dda4bc4a2f 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > @@ -704,6 +704,7 @@ static const struct coresight_ops_source 
> > etm_source_ops = {
> >   };
> >   static const struct coresight_ops etm_cs_ops = {
> > +    .trace_id    = coresight_etm_get_trace_id,
> >       .source_ops    = &etm_source_ops,
> >   };
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/ 
> > drivers/hwtracing/coresight/coresight-etm4x-core.c
> > index 2c1a60577728..cfd116b87460 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > @@ -1067,6 +1067,7 @@ static const struct coresight_ops_source 
> > etm4_source_ops = {
> >   };
> >   static const struct coresight_ops etm4_cs_ops = {
> > +    .trace_id    = coresight_etm_get_trace_id,
> >       .source_ops    = &etm4_source_ops,
> >   };
> > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/ 
> > hwtracing/coresight/coresight-stm.c
> > index b581a30a1cd9..aca25b5e3be2 100644
> > --- a/drivers/hwtracing/coresight/coresight-stm.c
> > +++ b/drivers/hwtracing/coresight/coresight-stm.c
> > @@ -281,12 +281,23 @@ static void stm_disable(struct coresight_device 
> > *csdev,
> >       }
> >   }
> > +static int stm_trace_id(struct coresight_device *csdev, 
> > __maybe_unused enum cs_mode mode,
> > +            __maybe_unused struct coresight_device *sink)
> > +{
> > +    struct stm_drvdata *drvdata;
> > +
> > +    drvdata = dev_get_drvdata(csdev->dev.parent);
> > +
> > +    return drvdata->traceid;
> > +}
> > +
> >   static const struct coresight_ops_source stm_source_ops = {
> >       .enable        = stm_enable,
> >       .disable    = stm_disable,
> >   };
> >   static const struct coresight_ops stm_cs_ops = {
> > +    .trace_id    = stm_trace_id,
> >       .source_ops    = &stm_source_ops,
> >   };
> > diff --git a/drivers/hwtracing/coresight/coresight-tpda.c b/drivers/ 
> > hwtracing/coresight/coresight-tpda.c
> > index 189a4abc2561..68079169b11b 100644
> > --- a/drivers/hwtracing/coresight/coresight-tpda.c
> > +++ b/drivers/hwtracing/coresight/coresight-tpda.c
> > @@ -241,12 +241,23 @@ static void tpda_disable(struct coresight_device 
> > *csdev,
> >       dev_dbg(drvdata->dev, "TPDA inport %d disabled\n", in->dest_port);
> >   }
> > +static int tpda_trace_id(struct coresight_device *csdev, 
> > __maybe_unused enum cs_mode mode,
> > +             __maybe_unused struct coresight_device *sink)
> > +{
> > +    struct tpda_drvdata *drvdata;
> > +
> > +    drvdata = dev_get_drvdata(csdev->dev.parent);
> > +
> > +    return drvdata->atid;
> > +}
> > +
> >   static const struct coresight_ops_link tpda_link_ops = {
> >       .enable        = tpda_enable,
> >       .disable    = tpda_disable,
> >   };
> >   static const struct coresight_ops tpda_cs_ops = {
> > +    .trace_id    = tpda_trace_id,
> >       .link_ops    = &tpda_link_ops,
> >   };
> > diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> > index 157c4bd009a1..ce89ad24c2a2 100644
> > --- a/include/linux/coresight.h
> > +++ b/include/linux/coresight.h
> > @@ -335,6 +335,7 @@ enum cs_mode {
> >       CS_MODE_PERF,
> >   };
> > +#define coresight_ops(csdev)    csdev->ops
> >   #define source_ops(csdev)    csdev->ops->source_ops
> >   #define sink_ops(csdev)        csdev->ops->sink_ops
> >   #define link_ops(csdev)        csdev->ops->link_ops
> > @@ -410,6 +411,8 @@ struct coresight_ops_helper {
> >   };
> >   struct coresight_ops {
> > +    int (*trace_id)(struct coresight_device *csdev, enum cs_mode mode,
> > +            struct coresight_device *sink);
> >       const struct coresight_ops_sink *sink_ops;
> >       const struct coresight_ops_link *link_ops;
> >       const struct coresight_ops_source *source_ops;
> > @@ -697,4 +700,6 @@ int coresight_init_driver(const char *drv, struct 
> > amba_driver *amba_drv,
> >   void coresight_remove_driver(struct amba_driver *amba_drv,
> >                    struct platform_driver *pdev_drv);
> > +int coresight_etm_get_trace_id(struct coresight_device *csdev, enum 
> > cs_mode mode,
> > +                   struct coresight_device *sink);
> >   #endif        /* _LINUX_COREISGHT_H */