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

[Suzuki K Poulose <suzuki.poulose@arm.com>]

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


> 
> 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 */