Re: [PATCH v6 2/2] coresight: Add label sysfs node support

[Jinlong Mao <quic_jinlmao@xxxxxxxxxxx>]

On 2024/12/18 17:38, Suzuki K Poulose wrote:
> On 17/12/2024 06:33, Mao Jinlong wrote:
> > For some coresight components like CTI and TPDM, there could be
> > numerous of them. From the node name, we can only get the type and
> > register address of the component. We can't identify the HW or the
> > system the component belongs to. Add label sysfs node support for
> > showing the intuitive name of the device.
> >
> > Signed-off-by: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> > ---
> >   .../testing/sysfs-bus-coresight-devices-cti   |  6 ++++
> >   .../sysfs-bus-coresight-devices-funnel        |  6 ++++
> >   .../testing/sysfs-bus-coresight-devices-tpdm  |  6 ++++
> >   drivers/hwtracing/coresight/coresight-sysfs.c | 32 +++++++++++++++++++
> >   4 files changed, 50 insertions(+)
>
> Do you think we need to name the devices using the label ? Or is this 
> enough ?
>
> Suzuki
Hi Suzuki,

In my opinion, we should use label as the device name.

It will be easier to identify the component with the folder name in 
/sys/bus/coresight/devices/


Thanks
Jinlong Mao

> > diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti 
> > b/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti
> > index bf2869c413e7..909670e0451a 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti
> > +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti
> > @@ -239,3 +239,9 @@ Date:        March 2020
> >   KernelVersion    5.7
> >   Contact:    Mike Leach or Mathieu Poirier
> >   Description:    (Write) Clear all channel / trigger programming.
> > +
> > +What:           /sys/bus/coresight/devices/<cti-name>/label
> > +Date:           Dec 2024
> > +KernelVersion   6.14
> > +Contact:        Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> > +Description:    (Read) Show hardware context information of device.
> > diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices- 
> > funnel b/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel
> > index d75acda5e1b3..944aad879aeb 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel
> > +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel
> > @@ -10,3 +10,9 @@ Date:        November 2014
> >   KernelVersion:    3.19
> >   Contact:    Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> >   Description:    (RW) Defines input port priority order.
> > +
> > +What:           /sys/bus/coresight/devices/<memory_map>.funnel/label
> > +Date:           Dec 2024
> > +KernelVersion   6.14
> > +Contact:        Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> > +Description:    (Read) Show hardware context information of device.
> > diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices- 
> > tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > index bf710ea6e0ef..309802246398 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > @@ -257,3 +257,9 @@ Contact:    Jinlong Mao (QUIC) 
> > <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang (QUIC) <quic_t
> >   Description:
> >           (RW) Set/Get the MSR(mux select register) for the CMB subunit
> >           TPDM.
> > +
> > +What:           /sys/bus/coresight/devices/<tpdm-name>/label
> > +Date:           Dec 2024
> > +KernelVersion   6.14
> > +Contact:        Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
> > +Description:    (Read) Show hardware context information of device.
> > diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/ 
> > hwtracing/coresight/coresight-sysfs.c
> > index a01c9e54e2ed..4af40cd7d75a 100644
> > --- a/drivers/hwtracing/coresight/coresight-sysfs.c
> > +++ b/drivers/hwtracing/coresight/coresight-sysfs.c
> > @@ -7,6 +7,7 @@
> >   #include <linux/device.h>
> >   #include <linux/idr.h>
> >   #include <linux/kernel.h>
> > +#include <linux/property.h>
> >   #include "coresight-priv.h"
> >   #include "coresight-trace-id.h"
> > @@ -366,18 +367,47 @@ static ssize_t enable_source_store(struct device 
> > *dev,
> >   }
> >   static DEVICE_ATTR_RW(enable_source);
> > +static ssize_t label_show(struct device *dev,
> > +        struct device_attribute *attr, char *buf)
> > +{
> > +
> > +    const char *str;
> > +    int ret = 0;
> > +
> > +    ret = fwnode_property_read_string(dev_fwnode(dev), "label", &str);
> > +    if (ret == 0)
> > +        return scnprintf(buf, PAGE_SIZE, "%s\n", str);
> > +    else
> > +        return ret;
> > +}
> > +static DEVICE_ATTR_RO(label);
> > +
> >   static struct attribute *coresight_sink_attrs[] = {
> >       &dev_attr_enable_sink.attr,
> > +    &dev_attr_label.attr,
> >       NULL,
> >   };
> >   ATTRIBUTE_GROUPS(coresight_sink);
> >   static struct attribute *coresight_source_attrs[] = {
> >       &dev_attr_enable_source.attr,
> > +    &dev_attr_label.attr,
> >       NULL,
> >   };
> >   ATTRIBUTE_GROUPS(coresight_source);
> > +static struct attribute *coresight_link_attrs[] = {
> > +    &dev_attr_label.attr,
> > +    NULL,
> > +};
> > +ATTRIBUTE_GROUPS(coresight_link);
> > +
> > +static struct attribute *coresight_helper_attrs[] = {
> > +    &dev_attr_label.attr,
> > +    NULL,
> > +};
> > +ATTRIBUTE_GROUPS(coresight_helper);
> > +
> >   const struct device_type coresight_dev_type[] = {
> >       [CORESIGHT_DEV_TYPE_SINK] = {
> >           .name = "sink",
> > @@ -385,6 +415,7 @@ const struct device_type coresight_dev_type[] = {
> >       },
> >       [CORESIGHT_DEV_TYPE_LINK] = {
> >           .name = "link",
> > +        .groups = coresight_link_groups,
> >       },
> >       [CORESIGHT_DEV_TYPE_LINKSINK] = {
> >           .name = "linksink",
> > @@ -396,6 +427,7 @@ const struct device_type coresight_dev_type[] = {
> >       },
> >       [CORESIGHT_DEV_TYPE_HELPER] = {
> >           .name = "helper",
> > +        .groups = coresight_helper_groups,
> >       }
> >   };
> >   /* Ensure the enum matches the names and groups */