Some UFS devices require delay after VCC power rail is turned off.
Introduce a device quirk "DELAY_AFTER_LPM" to add 5ms delay after VCC
power-off during suspend flow.

Link: https://lore.kernel.org/r/20200729051840.31318-2-stanley.chu@mediatek.comReviewed-by: NAndy Teng <andy.teng@mediatek.com>
Reviewed-by: NPeter Wang <peter.wang@mediatek.com>
Reviewed-by: NCan Guo <cang@codeaurora.org>
Acked-by: NAvri Altman <Avri.Altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Add missing setup_xfer_req() call in ufshcd_issue_devman_upiu_cmd() in
ufs-bsg path. Relocate existing setup_xfer_req() calls to a common place,
i.e., ufshcd_send_command(), to simplify the driver.

Link: https://lore.kernel.org/r/20200706060707.32608-3-stanley.chu@mediatek.comAcked-by: NAvri Altman <Avri.Altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Simplify recording command completion time in __ufshcd_transfer_req_compl()
by assigning lrbp->compl_time_stamp in a unified location.

Link: https://lore.kernel.org/r/20200706060707.32608-2-stanley.chu@mediatek.comAcked-by: NAvri Altman <Avri.Altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Wire up ufshcd.c with the UFS Crypto API, the block layer inline encryption
additions and the keyslot manager.

Many existing inline crypto devices require some additional behaviour not
specified in the UFSHCI v2.1 specification - as such the vendor specific
drivers will need to be updated where necessary to make it possible to use
those devices. Some of these changes have already been proposed upstream,
such as for the Qualcomm 845 SoC at
https://lkml.kernel.org/linux-scsi/20200501045111.665881-1-ebiggers@kernel.org/
and for ufs-mediatek at
https://lkml.kernel.org/linux-scsi/20200304022101.14165-1-stanley.chu@mediatek.com/

This patch has been tested on the db845c, sm8150-mtp and sm8250-mtp
(which have Qualcomm chipsets) and on some mediatek chipsets using these
aforementioned vendor specific driver updates.

Link: https://lore.kernel.org/r/20200706200414.2027450-4-satyat@google.comReviewed-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NSatya Tangirala <satyat@google.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Add the crypto registers and structs defined in v2.1 of the JEDEC UFSHCI
specification in preparation to add support for inline encryption to UFS.

Link: https://lore.kernel.org/r/20200706200414.2027450-2-satyat@google.comReviewed-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NSatya Tangirala <satyat@google.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

According to the UFS Spec, the Flags field in the UPIU is one byte in size,
not 4. Change it to be u8.

Link: https://lore.kernel.org/r/20200706123936.24799-1-huobean@gmail.comTested-by: NAlim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

If a UFS device is not qualified to use WriteBooster, either due to wrong
UFS version or device-specific quirks, then the capability in host shall be
disabled to prevent any WriteBooster operations in the future.

Link: https://lore.kernel.org/r/20200625030430.25048-1-stanley.chu@mediatek.com
Fixes: 3d17b9b5 ("scsi: ufs: Add write booster feature support")
Tested-by: NSteev Klimaszewski <steev@kali.org>
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The UFS load calculation is based on "total_time" and "busy_time" in a
devfreq window.  However, the source of time is different for both
parameters: "busy_time" is assigned from "jiffies" thus has different
accuracy from "total_time" which is assigned from ktime_get().

In addition, the time of window boundary is not exactly the same as the
starting busy time in this window if UFS is actually busy in the beginning
of the window. A similar accuracy error may also happen for the end of busy
time in current window.

To guarantee the precision of load calculation, we need to

1. Align time accuracy of both devfreq_dev_status.total_time and
   devfreq_dev_status.busy_time. For example, use "ktime_get()" directly.

2. Align the following timelines:
   - The beginning time of devfreq windows
   - The beginning of busy time in a new window
   - The end of busy time in the current window

Link: https://lore.kernel.org/r/20200611101043.6379-1-stanley.chu@mediatek.com
Fixes: a3cd5ec5 ("scsi: ufs: add load based scaling of UFS gear")
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Use the ftrace infrastructure to conditionally trace UFS UIC command
events.

New trace event "ufshcd_uic_command" is created, which samples the
following UFS UIC command data:

 - Device name
 - Optional identification string
 - UIC command opcode
 - UIC command argument1
 - UIC command argument2
 - UIC command argement3

Usage:
	echo 1 > /sys/kernel/debug/tracing/events/ufs/enable
	cat /sys/kernel/debug/tracing/trace_pipe

Link: https://lore.kernel.org/r/20200615072235.23042-3-stanley.chu@mediatek.comAcked-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Clean up the following items:

 - Sort vendor names in alphabetical order

 - Squash quirks as compact as possible in device table to enhance
   performance of the lookup

 - Sort device quirks in alphabetical order

Link: https://lore.kernel.org/r/20200612012625.6615-3-stanley.chu@mediatek.comReviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

It is confirmed that Micron device needs DELAY_BEFORE_LPM quirk to have a
delay before VCC is powered off. Sdd Micron vendor ID and this quirk for
Micron devices.

Link: https://lore.kernel.org/r/20200612012625.6615-2-stanley.chu@mediatek.comReviewed-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Add SPDX GPL-2.0 to UFS driver files that specified the GPL version 2
license, remove the full boilerplate text.

Link: https://lore.kernel.org/r/20200605200520.20831-2-huobean@gmail.comReviewed-by: NTomas Winkler <tomas.winkler@intel.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

For UFS 3.1, the normal unit descriptor is 10 bytes larger than the RPMB
unit. However, both descriptors share the same desc_idn, to cover both unit
descriptors with one length, we choose the normal unit descriptor length by
desc_index.

Link: https://lore.kernel.org/r/20200603091959.27618-6-huobean@gmail.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

At UFS initialization stage, to get the length of the descriptor,
ufshcd_read_desc_length() was being called 6 times. Instead, we will
capture the descriptor size the first time we'll read it.

Delete unnecessary redundant code, remove ufshcd_read_desc_length(),
ufshcd_init_desc_sizes(), and boost UFS initialization.

Link: https://lore.kernel.org/r/20200603091959.27618-5-huobean@gmail.comAcked-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NBart van Assche <bvanassche@acm.org>
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

If param_offset is not 0, the memcpy length shouldn't be the true
descriptor length.

Link: https://lore.kernel.org/r/20200603091959.27618-4-huobean@gmail.comAcked-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Delete ufshcd_read_desc(). Instead, let caller directly call
ufshcd_read_desc_param().

Link: https://lore.kernel.org/r/20200603091959.27618-3-huobean@gmail.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NBart van Assche <bvanassche@acm.org>
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

For the UFS device, the maximum descriptor size is 255, max_t called on
ufs_get_device_desc() is useless.

Link: https://lore.kernel.org/r/20200603091959.27618-2-huobean@gmail.comReviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Acked-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NBart van Assche <bvanassche@acm.org>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some controller like Exynos determines if FATAL ERROR (0x7) in OCS field in
UTRD occurs for values other than GOOD (0x0) in STATUS field in response
upiu as well as errors that a host controller can't cover.  This patch is
to prevent from reporting command results in those cases.

Link: https://lore.kernel.org/r/20200528011658.71590-6-alim.akhtar@samsung.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NKiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some UFS host controllers like Exynos uses granularities of PRDT length and
offset as bytes, whereas others use actual segment count.

Link: https://lore.kernel.org/r/20200528011658.71590-5-alim.akhtar@samsung.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NKiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some host controllers don't support host controller enable via HCE.

Link: https://lore.kernel.org/r/20200528011658.71590-4-alim.akhtar@samsung.comReviewed-by: NCan Guo <cang@codeaurora.org>
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NSeungwon Jeon <essuuj@gmail.com>
Signed-off-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some host controllers support interrupt aggregation but don't allow
resetting counter and timer in software.

Link: https://lore.kernel.org/r/20200528011658.71590-3-alim.akhtar@samsung.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NSeungwon Jeon <essuuj@gmail.com>
Signed-off-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

With the correct behavior, setting the bit to '0' indicates clear and '1'
indicates no change. If host controller handles this the other way around,
UFSHCI_QUIRK_BROKEN_REQ_LIST_CLR can be used.

Link: https://lore.kernel.org/r/20200528011658.71590-2-alim.akhtar@samsung.comReviewed-by: NCan Guo <cang@codeaurora.org>
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NSeungwon Jeon <essuuj@gmail.com>
Signed-off-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

In ufshcd_probe_hba(), all BKOP SW tracking variables can be reset together
in ufshcd_force_reset_auto_bkops(), thus urgent_bkop_lvl initialization in
the beginning of ufshcd_probe_hba() can be merged into
ufshcd_force_reset_auto_bkops().

Link: https://lore.kernel.org/r/20200530141200.4616-1-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Urgent bkops level is used to compare against actual bkops status read from
UFS device. Urgent bkops level is set during initialization and might be
updated in exception event handler during runtime. But it should not be
updated to the actual bkops status every time when auto bkops is toggled.
Otherwise, if urgent bkops level is updated to 0, auto bkops shall always
be kept enabled.

Link: https://lore.kernel.org/r/1590632686-17866-1-git-send-email-cang@codeaurora.org
Fixes: 24366c2a ("scsi: ufs: Recheck bkops level if bkops is disabled")
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NCan Guo <cang@codeaurora.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Currently UFS host driver promises VCC supply if UFS device needs to do
WriteBooster flush during runtime suspend.

However the UFS specification mentions:

"While the flushing operation is in progress, the device is in Active power
mode."

Therefore UFS host driver needs to promise more: Keep UFS device as "Active
power mode", otherwise UFS device shall not do any flush if device enters
Sleep or PowerDown power mode.  Similarly, the same promises shall be
applied if device needs urgent BKOP during runtime suspend.

Fix this by not changing device power mode if WriteBooster flush or urgent
BKOP is required in ufshcd_suspend().

Now, if device finishes its job but is not resumed for a very long time,
system will have unnecessary power drain because VCC is still supplied. A
method to re-check the threshold of keeping VCC supply is required to fix
the power drain. However, the threshold re-check needs to re-activate the
link first because the decision depends on the latest device status.

Also introduce a delayed work to force runtime resume after a certain delay
during runtime suspend. This makes threshold re-check happen natually in
the entry of the next runtime-suspend. The device can continue its
WriteBooster flush or urgent BKOP jobs soon after resumed if device has no
upcoming requests and link enters hibern8 state either by Auto-Hibern8 or
hibern8 during clk-gating scheme. This solution not only prevents power
drain but also makes as much use of time as possible for device's
background jobs.

Link: https://lore.kernel.org/r/20200522083212.4008-5-stanley.chu@mediatek.comReviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

For WriteBooster feature related attributes, the index used by query shall
be LUN ID if LU Dedicated buffer mode is enabled.

Link: https://lore.kernel.org/r/20200522083212.4008-4-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

According to the UFS specification, WriteBooster is officially supported by
UFS 2.2.

Since UFS 2.2 specification has been finalized in JEDEC and such devices
have also showed up in the market, modify the checking rule for
ufshcd_wb_probe() to allow these devices to enable WriteBooster.

Link: https://lore.kernel.org/r/20200522083212.4008-3-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The whole UFS host instance has been zero-initialized by scsi_host_alloc(),
thus UFS driver does not need to clear "dev_info" member specifically in
ufshcd_device_params_init().

Simply remove the unnecessary code.

Link: https://lore.kernel.org/r/20200522083212.4008-2-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The ufshcd_wait_for_register() function either sleeps or spins until the
specified register has reached the desired value. Busy-waiting is not only
considered a bad practice but also has a bad impact on energy
consumption. Always sleep instead of spinning by making sure that all
ufshcd_wait_for_register() calls happen from a context where it is allowed
to sleep. The only function call that has to be moved is the
ufshcd_hba_stop() call in ufshcd_host_reset_and_restore().

Link: https://lore.kernel.org/r/20200507222750.19113-1-bvanassche@acm.org
Cc: Can Guo <cang@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Asutosh Das <asutoshd@codeaurora.org>
Tested-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NStanley Chu <stanley.chu@mediatek.com>
Reviewed-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Allow flush threshold for WriteBooster to be customizable by vendors. To
achieve this, make the value a variable in struct ufs_hba_variant_params.

Also introduce UFS_WB_BUF_REMAIN_PERCENT() macro to provide a more flexible
way to specify WriteBooster available buffer values.

Link: https://lore.kernel.org/r/20200509093716.21010-4-stanley.chu@mediatek.comReviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The UFS driver is growing more and more customizable parameters. Collect
them in one place.

Link: https://lore.kernel.org/r/20200509093716.21010-2-stanley.chu@mediatek.comReviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Small cleanup as below items,

 1. Use ufshcd_is_wb_allowed() directly instead of ufshcd_wb_sup() since
    ufshcd_wb_sup() just returns the result of ufshcd_is_wb_allowed().

 2. In ufshcd_suspend(), "else if (!ufshcd_is_runtime_pm(pm_op)) can be
    simplified to "else" since both have the same meaning.

This patch does not change any functionality.

Link: https://lore.kernel.org/r/20200508080115.24233-9-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

According to UFS specification, there are two WriteBooster mode of
operations: "LU dedicated buffer" mode and "shared buffer" mode.  In the
"LU dedicated buffer" mode, the WriteBooster Buffer is dedicated to a
logical unit.

If the device supports the "LU dedicated buffer" mode, this mode is
configured by setting bWriteBoosterBufferType to 00h. The logical unit
WriteBooster Buffer size is configured by setting the
dLUNumWriteBoosterBufferAllocUnits field of the related Unit
Descriptor. Only a value greater than zero enables the WriteBooster feature
in the logical unit.

Modify ufshcd_wb_probe() as above description to support LU Dedicated
buffer mode.

Note that according to UFS 3.1 specification, the valid value of
bDeviceMaxWriteBoosterLUs parameter in Geometry Descriptor is 1, which
means at most one LUN can have WriteBooster buffer in "LU dedicated buffer
mode". Therefore this patch supports only one LUN with WriteBooster
enabled. All WriteBooster related sysfs nodes are specifically mapped to
the LUN with WriteBooster enabled in LU Dedicated buffer mode.

Link: https://lore.kernel.org/r/20200508080115.24233-7-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

For preparation of LU Dedicated buffer mode support on WriteBooster
feature, "index" parameter shall be added and allowed to be specified by
callers.

Link: https://lore.kernel.org/r/20200508080115.24233-6-stanley.chu@mediatek.comReviewed-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NCan Guo <cang@codeaurora.org>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Export ufs_fixup_device_setup() to allow vendors to re-use it for fixing
device quriks on specified UFS hosts.

Link: https://lore.kernel.org/r/20200508080115.24233-4-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Some UFS deivces may have required device quirks or have non-standard
features which are enabled only on specified UFS hosts or for special
customers.

To not "pollute" common device quirk list, i.e. ufs_fixups table, for those
devices mentioned above, introduce "fixup_dev_quirks" vops to allow vendors
to fix or modify device quirks accordingly.

Link: https://lore.kernel.org/r/20200508080115.24233-3-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The WriteBooster feature can be supported by some pre-3.1 UFS devices by
upgrading firmware.

To enable WriteBooster feature in such devices, introduce a device quirk to
relax the entrance condition of ufshcd_wb_probe() to allow host driver to
check those devices' WriteBooster capability.

WriteBooster feature can be available if below all conditions are
satisfied,

 1. Host enables WriteBooster capability

 2. UFS 3.1 device or UFS pre-3.1 device with quirk
    UFS_DEVICE_QUIRK_SUPPORT_EXTENDED_FEATURES enabled

 3. The device descriptor shall have DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP
    field

 4. WriteBooster support is specified in above field

Link: https://lore.kernel.org/r/20200508080115.24233-2-stanley.chu@mediatek.comReviewed-by: NAvri Altman <avri.altman@wdc.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare variable-length
types such as these ones is a flexible array member[1][2], introduced in
C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in which
the sizeof operator is being incorrectly/erroneously applied to zero-length
arrays and the result is zero. Such instances may be hiding some bugs. So,
this work (flexible-array member conversions) will also help to get
completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200507192550.GA16683@embeddedorSigned-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The write performance of TLC NAND is considerably lower than SLC NAND.
Using SLC NAND as a WriteBooster Buffer enables the write request to be
processed with lower latency and improves the overall write performance.

Adds support for shared-buffer mode WriteBooster.

WriteBooster enable: SW enables it when clocks are scaled up, thus it's
enabled only in high load conditions.

WriteBooster disable: SW will disable the feature, when clocks are scaled
down. Thus writes would go as normal writes.

To keep the endurance of the WriteBooster Buffer at a maximum, this
load-based toggling is adopted.

Link: https://lore.kernel.org/r/2871444d9083b0e9323ef6d8ff1b544b7784adc9.1587591527.git.asutoshd@codeaurora.orgReviewed-by: NAvri Altman <avri.altman@wdc.com>
Signed-off-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NSubhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Fix the following coccicheck warning:

drivers/scsi/ufs/ufshcd.c:4140:6-14: WARNING: Assignment of 0/1 to bool
variable.

Link: https://lore.kernel.org/r/20200426094305.24083-1-yanaijie@huawei.comSigned-off-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>