scsi: ufs: core: Add CPU latency QoS support for UFS driver

Register UFS driver to CPU latency PM QoS framework to improve UFS device
random I/O performance.

PM QoS initialization will insert new QoS request into the CPU latency QoS
list with the maximum latency PM_QOS_DEFAULT_VALUE value.

The UFS driver will vote for performance mode on scale up and power save
mode for scale down.

If clock scaling feature is not enabled then voting will be based on clock
on or off condition. Also provide a sysfs interface to enable/disable PM
QoS feature.

tiotest benchmark tool I/O performance results on sm8550 platform:

1. Without PM QoS support
Type (Speed in) | Average of 18 iterations
Random Write(IPOS) | 41065.13
Random Read(IPOS) | 37101.3

2. With PM QoS support
Type (Speed in) | Average of 18 iterations
Random Write(IPOS) | 46784.9
Random Read(IPOS) | 42943.4

(Improvement with PM QoS = ~15%).

Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Co-developed-by: Nitin Rawat <quic_nitirawa@quicinc.com>
Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
Co-developed-by: Naveen Kumar Goud Arepalli <quic_narepall@quicinc.com>
Signed-off-by: Naveen Kumar Goud Arepalli <quic_narepall@quicinc.com>
Signed-off-by: Maramaina Naresh <quic_mnaresh@quicinc.com>
Link: https://lore.kernel.org/r/20231219123706.6463-2-quic_mnaresh@quicinc.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Add sysfs node for UFS RTC update

Introduce a sysfs node named 'rtc_update_ms' within the kernel, enabling
user to adjust the RTC periodic update frequency to suit the specific
requirements of the system and UFS. Also, this patch allows the user to
disable/enable periodic update RTC in the UFS idle time.

Signed-off-by: Bean Huo <beanhuo@micron.com>
Link: https://lore.kernel.org/r/20231212220825.85255-4-beanhuo@iokpp.de
Acked-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: ufs-sysfs: Expose UFS power info

Having UFS power info available in sysfs makes it easier to tell the state
of the link during runtime considering we have a bunch of power saving
features and various combinations for backward compatibility.

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Can Guo <quic_cang@quicinc.com>
Link: https://lore.kernel.org/r/1698890324-7374-1-git-send-email-quic_cang@quicinc.com
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Remove HPB support

Interest among UFS users in HPB has reduced significantly. I am not aware
of any current users of the HPB functionality. Hence remove HPB support
from the kernel.

A note: the work in JEDEC on a successor for HPB is nearing completion.
Zoned storage for UFS or ZUFS combines the UFS standard with ZBC-2.

Acked-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: ChanWoo Lee <cw9316.lee@samsung.com>
Cc: Daejun Park <daejun7.park@samsung.com>
Cc: Keoseong Park <keosung.park@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230719165758.2787573-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: wb: Add explicit flush_threshold sysfs attribute

There are three flags that control Write Booster Feature:

1. WB ON/OFF
2. WB Hibern Flush ON/OFF (implicitly)
3. WB Flush ON/OFF (explicit)

In the case of "Hibern Flush", one of the conditions for flush WB buffer is
that avail_wb_buff < wb_flush_threshold.

As we know, different users have different requirements for power
consumption and performance. Therefore, we need the ability to manually set
wb_flush_threshold, so that users can easily and flexibly adjust the
wb_flush_threshold value, thereby achieving a balance between power
consumption and performance.

So the sysfs attribute that controls this is necessary.

wb_flush_threshold represents the threshold for flushing WB buffer, whose
value expressed in unit of 10% granularity, such as '1' representing 10%,
'2' representing 20%, and so on.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230613022240.16595-1-luhongfei@vivo.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: Ungate the clock synchronously

Ungating the clock asynchronously causes ufshcd_queuecommand() to return
SCSI_MLQUEUE_HOST_BUSY and hence causes commands to be requeued. This is
suboptimal. Allow ufshcd_queuecommand() to sleep such that clock ungating
does not trigger command requeuing. Remove the ufshcd_scsi_block_requests()
and ufshcd_scsi_unblock_requests() calls because these are no longer
needed. The flush_work(&hba->clk_gating.ungate_work) call is sufficient to
make the SCSI core wait for clock ungating to complete.

Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230529202640.11883-6-bvanassche@acm.org
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Use is_visible to control UFS unit descriptor sysfs nodes

UFS Boot and Device W-LUs do not have unit descriptors and RPMB does not
support WB. Use is_visible() to control which nodes are visible and which
are not.

Signed-off-by: Bean Huo <beanhuo@micron.com>
Link: https://lore.kernel.org/r/20221025222430.277768-4-beanhuo@iokpp.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Arthur Simchaev <arthur.simchaev@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Revert "WB is only available on LUN #0 to #7"

Ccommit d3d9c4570285 ("scsi: ufs: Fix memory corruption by
ufshcd_read_desc_param()") has properly fixed stack overflow issue.

As a result, commit a2fca52ee640 ("scsi: ufs: WB is only available on LUN
#0 to #7") is no longer required. Revert it.

Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Link: https://lore.kernel.org/r/20221025222430.277768-2-beanhuo@iokpp.de
Reviewed-by: Arthur Simchaev <arthur.simchaev@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Print UFSHCD capabilities in controller's sysfs node

Userspace may want to manually control when the data should go into
WriteBooster buffer. The control happens via "wb_on" node, but presently,
there is no simple way to check if WriteBooster is supported and
enabled.

Expose the Write Booster and Clock Scaling capabilities to be able to
determine if the Write Booster is available and if its manual control is
blocked by Clock Scaling mechanism.

Link: https://lore.kernel.org/r/20220829081845.v8.1.Ibf9efc9be50783eeee55befa2270b7d38552354c@changeid
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Daniil Lunev <dlunev@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: wb: Modify messages

Modify messages to fit the format of others.

Link: https://lore.kernel.org/r/20220804075519epcms2p148b6ae956b172925b26304b50d6a0da9@epcms2p1
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: wb: Introduce ufshcd_is_wb_buf_flush_allowed()

The explicit flushing should check the following:

- UFSHCD_CAP_WB_EN

- UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL

Add helper to improve readability.

Link: https://lore.kernel.org/r/20220804075444epcms2p4a0520880262281f02be65ce0fe50602d@epcms2p4
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Acked-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: wb: Add explicit flush sysfs attribute

There is the following quirk to bypass "WB Flush" in Write Booster.

- UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL

If this quirk is not set, there is no knob that can control "WB Flush".

There are three flags that control Write Booster Feature:

1. WB ON/OFF
2. WB Hibern Flush ON/OFF (implicitly)
3. WB Flush ON/OFF (explicit)

The sysfs attribute that controls the WB was implemented. (1)

In the case of "Hibern Flush", it is always good to turn on. Control may
not be required. (2)

Finally, "Flush" may be necessary because the Auto-Hibern8 is not supported
in a specific environment. So the sysfs attribute that controls this is
necessary. (3)

Link: https://lore.kernel.org/r/20220804075354epcms2p8c21c894b4e28840c5fc651875b7f435f@epcms2p8
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: core: Allow host driver to disable wb toggling during clock scaling

Mediatek UFS does not want to toggle write booster during clock scaling.
Permit host driver to disable wb toggling during clock scaling.

Introduce a flag UFSHCD_CAP_WB_WITH_CLK_SCALING to decouple WB and clock
scaling. UFSHCD_CAP_WB_WITH_CLK_SCALING is only valid when
UFSHCD_CAP_CLK_SCALING is set. Just like UFSHCD_CAP_HIBERN8_WITH_CLK_GATING
is valid only when UFSHCD_CAP_CLK_GATING set.

Set UFSHCD_CAP_WB_WITH_CLK_SCALING for qcom to compatible legacy design at
the same time.

Link: https://lore.kernel.org/r/20220804025422.18803-1-peter.wang@mediatek.com
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

scsi: ufs: Split the drivers/scsi/ufs directory

Split the drivers/scsi/ufs directory into 'core' and 'host' directories
under the drivers/ufs/ directory. Move shared header files into the
include/ufs/ directory. This separation makes it clear which header files
UFS drivers are allowed to include (include/ufs/*.h) and which header files
UFS drivers are not allowed to include (drivers/ufs/core/*.h).

Update the MAINTAINERS file. Add myself as a UFS reviewer.

Link: https://lore.kernel.org/r/20220511212552.655341-1-bvanassche@acm.org
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Keoseong Park <keosung.park@samsung.com>
Tested-by: Bean Huo <beanhuo@micron.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Acked-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>