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SubjectRE: [PATCH v3] scsi: ufs: Make sysfs attributes writable
Date
Hi Evan,

> -----Original Message-----
> From: Evan Green <evgreen@chromium.org>
> Sent: Wednesday, July 25, 2018 11:15 PM
> To: Vinayak Holikatti <vinholikatti@gmail.com>; James E.J. Bottomley <jejb@linux.vnet.ibm.com>; Martin K. Petersen
> <martin.petersen@oracle.com>; Stanislav Nijnikov <Stanislav.Nijnikov@wdc.com>; Adrian Hunter <adrian.hunter@intel.com>; linux-
> kernel@vger.kernel.org; linux-scsi@vger.kernel.org; Bart Van Assche <Bart.VanAssche@wdc.com>
> Cc: Evan Green <evgreen@chromium.org>
> Subject: [PATCH v3] scsi: ufs: Make sysfs attributes writable
>
> This change makes the UFS controller's sysfs attributes writable, which
> will enable users to modify attributes. This can be useful during factory
> provisioning for setting up critical attributes like the reference clock
> frequency.
>
> Signed-off-by: Evan Green <evgreen@chromium.org>
> ---
> Configfs was determined to be the preferred mechanism for writing the
> config descriptor, but attributes also need to be written during setup,
> and are already present in sysfs. Making these attributes writable is
> also helpful for debugging and experimentation.
>
> Changes since v2:
> - Removed the configuration descriptor changes from the series,
> since configfs was the preferred way to write to that, leaving only
> this change.
>
> Changes since v1:
> - Reworked the interface to show each unit of the config
> descriptor as a separate directory, rather than the previous method I
> had of a file for selecting the unit, and then a common set of files
> that interacted with whichever unit was selected. I did some kobject
> magic to accomplish this. I noticed from Greg KH's reply to Sayali's
> patches [1] that configfs might be the preferred method. Let me know
> if I should abandon this series in favor of Sayali's, with the
> possible exception of "Make sysfs attributes writable".
> - Squashed documentation changes into their respective code
> changes.
> - I decided to keep the config descriptor attributes as their
> own files, rather than hiding writes behind device descriptor and unit
> descriptor, as I think that's more future proof and true to the UFS spec.
>
> [1] https://lkml.org/lkml/2018/6/8/210
>
> Documentation/ABI/testing/sysfs-driver-ufs | 17 +--------
> drivers/scsi/ufs/ufs-sysfs.c | 58 ++++++++++++++++++++----------
> 2 files changed, 40 insertions(+), 35 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
> index 016724ec26d5..44f3b9691e59 100644
> --- a/Documentation/ABI/testing/sysfs-driver-ufs
> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> @@ -685,7 +685,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the boot lun enabled UFS device attribute.
> The full information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/current_power_mode
> Date: February 2018
> @@ -693,7 +692,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the current power mode UFS device attribute.
> The full information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/active_icc_level
> Date: February 2018
> @@ -701,7 +699,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the active icc level UFS device attribute.
> The full information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/ooo_data_enabled
> Date: February 2018
> @@ -709,7 +706,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the out of order data transfer enabled UFS
> device attribute. The full information about the attribute
> could be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/bkops_status
> Date: February 2018
> @@ -717,7 +713,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the background operations status UFS device
> attribute. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/purge_status
> Date: February 2018
> @@ -725,7 +720,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the purge operation status UFS device
> attribute. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/max_data_in_size
> Date: February 2018
> @@ -733,7 +727,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file shows the maximum data size in a DATA IN
> UPIU. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/max_data_out_size
> Date: February 2018
> @@ -741,7 +734,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file shows the maximum number of bytes that can be
> requested with a READY TO TRANSFER UPIU. The full information
> about the attribute could be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/reference_clock_frequency
> Date: February 2018
> @@ -749,14 +741,13 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the reference clock frequency UFS device
> attribute. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/configuration_descriptor_lock
> Date: February 2018
> Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file shows whether the configuration descriptor is locked.
> The full information about the attribute could be found at
> - UFS specifications 2.1. The file is read only.
> + UFS specifications 2.1.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/max_number_of_rtt
> Date: February 2018
> @@ -765,7 +756,6 @@ Description: This file provides the maximum current number of
> outstanding RTTs in device that is allowed. The full
> information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/exception_event_control
> Date: February 2018
> @@ -773,7 +763,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the exception event control UFS device
> attribute. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/exception_event_status
> Date: February 2018
> @@ -781,7 +770,6 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the exception event status UFS device
> attribute. The full information about the attribute could
> be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/ffu_status
> Date: February 2018
> @@ -789,14 +777,12 @@ Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file provides the ffu status UFS device attribute.
> The full information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/psa_state
> Date: February 2018
> Contact: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
> Description: This file show the PSA feature status. The full information
> about the attribute could be found at UFS specifications 2.1.
> - The file is read only.
>
> What: /sys/bus/platform/drivers/ufshcd/*/attributes/psa_data_size
> Date: February 2018
> @@ -805,7 +791,6 @@ Description: This file shows the amount of data that the host plans to
> load to all logical units in pre-soldering state.
> The full information about the attribute could be found at
> UFS specifications 2.1.
> - The file is read only.
>
>
> What: /sys/class/scsi_device/*/device/dyn_cap_needed
> diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
> index 8d9332bb7d0c..5e286b9d1aea 100644
> --- a/drivers/scsi/ufs/ufs-sysfs.c
> +++ b/drivers/scsi/ufs/ufs-sysfs.c
> @@ -655,7 +655,7 @@ static const struct attribute_group ufs_sysfs_flags_group = {
> .attrs = ufs_sysfs_device_flags,
> };
>
> -#define UFS_ATTRIBUTE(_name, _uname) \
> +#define UFS_ATTRIBUTE_SHOW(_name, _uname) \
> static ssize_t _name##_show(struct device *dev, \
> struct device_attribute *attr, char *buf) \
> { \
> @@ -665,25 +665,45 @@ static ssize_t _name##_show(struct device *dev, \
> QUERY_ATTR_IDN##_uname, 0, 0, &value)) \
> return -EINVAL; \
> return sprintf(buf, "0x%08X\n", value); \
> -} \
> -static DEVICE_ATTR_RO(_name)
> +}
>
> -UFS_ATTRIBUTE(boot_lun_enabled, _BOOT_LU_EN);
> -UFS_ATTRIBUTE(current_power_mode, _POWER_MODE);
> -UFS_ATTRIBUTE(active_icc_level, _ACTIVE_ICC_LVL);
> -UFS_ATTRIBUTE(ooo_data_enabled, _OOO_DATA_EN);
> -UFS_ATTRIBUTE(bkops_status, _BKOPS_STATUS);
> -UFS_ATTRIBUTE(purge_status, _PURGE_STATUS);
> -UFS_ATTRIBUTE(max_data_in_size, _MAX_DATA_IN);
> -UFS_ATTRIBUTE(max_data_out_size, _MAX_DATA_OUT);
> -UFS_ATTRIBUTE(reference_clock_frequency, _REF_CLK_FREQ);
> -UFS_ATTRIBUTE(configuration_descriptor_lock, _CONF_DESC_LOCK);
> -UFS_ATTRIBUTE(max_number_of_rtt, _MAX_NUM_OF_RTT);
> -UFS_ATTRIBUTE(exception_event_control, _EE_CONTROL);
> -UFS_ATTRIBUTE(exception_event_status, _EE_STATUS);
> -UFS_ATTRIBUTE(ffu_status, _FFU_STATUS);
> -UFS_ATTRIBUTE(psa_state, _PSA_STATE);
> -UFS_ATTRIBUTE(psa_data_size, _PSA_DATA_SIZE);
> +#define UFS_ATTRIBUTE_RO(_name, _uname) \
> +UFS_ATTRIBUTE_SHOW(_name, _uname) \
> +DEVICE_ATTR_RO(_name)
It should be static here.

> +
> +#define UFS_ATTRIBUTE_RW(_name, _uname) \
> +UFS_ATTRIBUTE_SHOW(_name, _uname) \
> +static ssize_t _name##_store(struct device *dev, \
> + struct device_attribute *attr, const char *buf, \
> + size_t count) \
> +{ \
> + struct ufs_hba *hba = dev_get_drvdata(dev); \
> + u32 value; \
> + if (kstrtou32(buf, 0, &value)) \
> + return -EINVAL; \
> + if (ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR, \
> + QUERY_ATTR_IDN##_uname, 0, 0, &value)) \
> + return -EINVAL; \
> + return count; \
> +} \
> +static DEVICE_ATTR_RW(_name)
> +
> +UFS_ATTRIBUTE_RW(boot_lun_enabled, _BOOT_LU_EN);
> +UFS_ATTRIBUTE_RO(current_power_mode, _POWER_MODE);
> +UFS_ATTRIBUTE_RW(active_icc_level, _ACTIVE_ICC_LVL);
> +UFS_ATTRIBUTE_RW(ooo_data_enabled, _OOO_DATA_EN);
I would prefer to leave "write once" attributes as read-only.

> +UFS_ATTRIBUTE_RO(bkops_status, _BKOPS_STATUS);
> +UFS_ATTRIBUTE_RO(purge_status, _PURGE_STATUS);
> +UFS_ATTRIBUTE_RW(max_data_in_size, _MAX_DATA_IN);
> +UFS_ATTRIBUTE_RW(max_data_out_size, _MAX_DATA_OUT);
> +UFS_ATTRIBUTE_RW(reference_clock_frequency, _REF_CLK_FREQ);
> +UFS_ATTRIBUTE_RW(configuration_descriptor_lock, _CONF_DESC_LOCK);
Same here, "write once" attribute.

> +UFS_ATTRIBUTE_RW(max_number_of_rtt, _MAX_NUM_OF_RTT);
> +UFS_ATTRIBUTE_RW(exception_event_control, _EE_CONTROL);
> +UFS_ATTRIBUTE_RW(exception_event_status, _EE_STATUS);
This one is read only attribute.

> +UFS_ATTRIBUTE_RO(ffu_status, _FFU_STATUS);
> +UFS_ATTRIBUTE_RO(psa_state, _PSA_STATE);
> +UFS_ATTRIBUTE_RO(psa_data_size, _PSA_DATA_SIZE);
>
> static struct attribute *ufs_sysfs_attributes[] = {
> &dev_attr_boot_lun_enabled.attr,
> --
> 2.16.4

I would add some write option to some flags as well. For example, enabling/
disabling the background operations could be very useful.

Regards
Stanislav

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