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

[Jinlong Mao <quic_jinlmao@quicinc.com>]

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@quicinc.com>
>> ---
>>   .../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@quicinc.com>
>> +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@linaro.org>
>>   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@quicinc.com>
>> +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@quicinc.com>, 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@quicinc.com>
>> +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 */
>