Re: [PATCH v6] ufs: core: print UFSHCD capabilities in controller's sysfs node

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Aug 03, 2022 at 07:50:07AM +1000, Daniil Lunev wrote:
> Allows userspace to check if Clock Scaling and Write Booster are
> supported.
> 
> Signed-off-by: Daniil Lunev <dlunev@chromium.org>
> 
> ---
> 
> Changes in v6:
> * Add comment to clarify meaning of the "capbilities" sysfs group.
> 
> Changes in v5:
> * Correct wording for clock scaling.
> * Correct wording for the commit message.
> 
> Changes in v4:
> * Dropped crypto node per Eric Biggers mentioning it can be queried from
>   disk's queue node
> 
> Changes in v3:
> * Expose each capability individually.
> * Update documentation to represent new scheme.
> 
> Changes in v2:
> * Add documentation entry for the new sysfs node.
> 
>  Documentation/ABI/testing/sysfs-driver-ufs | 26 +++++++++++++++
>  drivers/ufs/core/ufs-sysfs.c               | 37 ++++++++++++++++++++++
>  2 files changed, 63 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
> index 6b248abb1bd71..1750a9b84ce0f 100644
> --- a/Documentation/ABI/testing/sysfs-driver-ufs
> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> @@ -1591,6 +1591,32 @@ Description:	This entry shows the status of HPB.
>  
>  		The file is read only.
>  
> +What:		/sys/bus/platform/drivers/ufshcd/*/capabilities/clock_scaling
> +What:		/sys/bus/platform/devices/*.ufs/capabilities/clock_scaling
> +Date:		July 2022
> +Contact:	Daniil Lunev <dlunev@chromium.org>
> +Description:	Indicates status of clock scaling.
> +
> +		== ============================
> +		0  Clock scaling is not supported.
> +		1  Clock scaling is supported.
> +		== ============================
> +
> +		The file is read only.
> +
> +What:		/sys/bus/platform/drivers/ufshcd/*/capabilities/write_booster
> +What:		/sys/bus/platform/devices/*.ufs/capabilities/write_booster
> +Date:		July 2022
> +Contact:	Daniil Lunev <dlunev@chromium.org>
> +Description:	Indicates status of Write Booster.
> +
> +		== ============================
> +		0  Write Booster can not be enabled.
> +		1  Write Booster can be enabled.
> +		== ============================
> +
> +		The file is read only.
> +
>  What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld
>  Date:		February 2021
>  Contact:	Avri Altman <avri.altman@wdc.com>
> diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
> index 0a088b47d5570..4149cdf19de92 100644
> --- a/drivers/ufs/core/ufs-sysfs.c
> +++ b/drivers/ufs/core/ufs-sysfs.c
> @@ -279,6 +279,42 @@ static const struct attribute_group ufs_sysfs_default_group = {
>  	.attrs = ufs_sysfs_ufshcd_attrs,
>  };
>  
> +static ssize_t clock_scaling_show(struct device *dev, struct device_attribute *attr,
> +				  char *buf)
> +{
> +	struct ufs_hba *hba = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "%d\n", ufshcd_is_clkscaling_supported(hba));
> +}
> +
> +static ssize_t write_booster_show(struct device *dev, struct device_attribute *attr,
> +				  char *buf)
> +{
> +	struct ufs_hba *hba = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "%d\n", ufshcd_is_wb_allowed(hba));
> +}
> +
> +static DEVICE_ATTR_RO(clock_scaling);
> +static DEVICE_ATTR_RO(write_booster);
> +
> +/*
> + * The "capabilities" sysfs group represents the effective capabilities of the
> + * host-device pair, i.e. the capabilities which are enabled in the driver for
> + * the specific host controller, supported by the host controller and are
> + * supported and/or have compatible configuration on the device side.

Why is this information not also in the Documentation/ABI/ entries as
well?

thanks,

greg k-h