Re: [PATCH v3 14/18] cxl/pmem: add id attribute to CXL based nvdimm

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 08 Nov 2022 10:26:42 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add an id group attribute for CXL based nvdimm object. The addition allows
> ndctl to display the "unique id" for the nvdimm. The serial number for the
> CXL memory device will be used for this id.
> 
> [
>   {
>       "dev":"nmem10",
>       "id":"0x4",
>       "security":"disabled"
>   },
> ]
> 
> The id attribute is needed by the ndctl security key management to setup a
> keyblob with a unique file name tied to the mem device.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  Documentation/ABI/testing/sysfs-bus-nvdimm |    6 ++++++
>  drivers/cxl/pmem.c                         |   28 +++++++++++++++++++++++++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-nvdimm b/Documentation/ABI/testing/sysfs-bus-nvdimm
> index 1c1f5acbf53d..91945211e53b 100644
> --- a/Documentation/ABI/testing/sysfs-bus-nvdimm
> +++ b/Documentation/ABI/testing/sysfs-bus-nvdimm
> @@ -41,3 +41,9 @@ KernelVersion:  5.18
>  Contact:        Kajol Jain <kjain@linux.ibm.com>
>  Description:	(RO) This sysfs file exposes the cpumask which is designated to
>  		to retrieve nvdimm pmu event counter data.
> +
> +What:		/sys/bus/nd/devices/nmemX/id
> +Date:		November 2022
> +KernelVersion:	6.2
> +Contact:	Dave Jiang <dave.jiang@intel.com>
> +Description:	(RO) Show the id (serial) of the device.
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index 24bec4ca3866..9209c7dd72d0 100644
> --- a/drivers/cxl/pmem.c
> +++ b/drivers/cxl/pmem.c
> @@ -48,6 +48,31 @@ static void unregister_nvdimm(void *nvdimm)
>  	cxl_nvd->bridge = NULL;
>  }
>  
> +static ssize_t id_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct nvdimm *nvdimm = to_nvdimm(dev);
> +	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
> +	struct cxl_dev_state *cxlds = cxl_nvd->cxlmd->cxlds;
> +
> +	return sysfs_emit(buf, "%lld\n", cxlds->serial);
> +}
> +static DEVICE_ATTR_RO(id);
> +
> +static struct attribute *cxl_dimm_attributes[] = {
> +	&dev_attr_id.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group cxl_dimm_attribute_group = {
> +	.name = "cxl",
> +	.attrs = cxl_dimm_attributes,
> +};
> +
> +static const struct attribute_group *cxl_dimm_attribute_groups[] = {
> +	&cxl_dimm_attribute_group,
> +	NULL
> +};
> +
>  static int cxl_nvdimm_probe(struct device *dev)
>  {
>  	struct cxl_nvdimm *cxl_nvd = to_cxl_nvdimm(dev);
> @@ -77,7 +102,8 @@ static int cxl_nvdimm_probe(struct device *dev)
>  	set_bit(ND_CMD_GET_CONFIG_SIZE, &cmd_mask);
>  	set_bit(ND_CMD_GET_CONFIG_DATA, &cmd_mask);
>  	set_bit(ND_CMD_SET_CONFIG_DATA, &cmd_mask);
> -	nvdimm = __nvdimm_create(cxl_nvb->nvdimm_bus, cxl_nvd, NULL, flags,
> +	nvdimm = __nvdimm_create(cxl_nvb->nvdimm_bus, cxl_nvd,
> +				 cxl_dimm_attribute_groups, flags,
>  				 cmd_mask, 0, NULL, NULL, cxl_security_ops, NULL);
>  	if (!nvdimm) {
>  		rc = -ENOMEM;
> 
>