usb: xhci-mtk: fix a short packet issue of gen1 isoc-in transfer

For Gen1 isoc-in transfer, host still send out unexpected ACK after device
finish the burst with a short packet, this will cause an exception on the
connected device, such as, a usb 4k camera.
It can be fixed by setting rxfifo depth less than 4k bytes, prefer to use
3k here, the side-effect is that may cause performance drop about 10%,
including bulk transfer.

Fixes: 926d60ae64a6 ("usb: xhci-mtk: modify the SOF/ITP interval for mt8195")
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20240104061640.7335-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: fix in-ep's start-split check failure

It's wrong to use the data length in a CS (in uframe x) to check whether
there is a SS (in uframe x-2), because for a isoc-in ep, it may need some
CS to receive data;
Save the count of SS in a uframe for isoc/intr in-eps to fix the issue.

Fixes: 5c954e030f55 ("usb: xhci-mtk: improve split scheduling by separate IN/OUT budget")
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20231118033011.22033-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: improve split scheduling by separate IN/OUT budget

Calculate the IN/OUT budget separately to improve the bandwidth schedule,
meanwhile should avoid Start-Split token overlap between IN and OUT
endpoints, and take into account the FS/LS bandwidth boundary in each
microframe and also in each FS frame.
Calculate the budget for SS of OUT eps and CS of IN eps, but not include
extra-cs, and always add at most extra-cs allowed.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20230830122820.18859-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add a bandwidth budget table

In order to estimate when fs/ls transactions appear on a downstream bus,
the host must calculate a best case full-speed budget, use a table to
track how many bytes occure in each microframe.
This patch is prepared for introducing an improved bandwidth scheduling.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20230830122820.18859-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add optional frame count clock

Add optional clock frmcnt_ck used on 4nm or advanced process SoC

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20230407062406.12575-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: remove bandwidth budget table

The bandwidth budget table is introduced to trace ideal bandwidth used
by each INT/ISOC endpoint, but in fact the endpoint may consume more
bandwidth and cause data transfer error, so it's better to leave some
margin. Obviously it's difficult to find the best margin for all cases,
instead take use of the worst-case scenario.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20220512064931.31670-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: host: xhci-mtk: Simplify supplies handling with regulator_bulk

Remove the custom functions xhci_mtk_ldos_{enable,disable}() by
switching to using regulator_bulk to perform the very same thing,
as the regulators are always either both enabled or both disabled.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220214111905.77903-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: allow bandwidth table rollover

xhci-mtk has 64 slots for periodic bandwidth calculations and each
slot represents byte budgets on a microframe. When an endpoint's
allocation sits on the boundary of the table, byte budgets' slot
can be rolled over but the current implementation doesn't.

This patch allows the microframe index rollover and prevent
out-of-bounds array access.

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210827033105.26595-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: Do not use xhci's virt_dev in drop_endpoint

xhci-mtk depends on xhci's internal virt_dev when it retrieves its
internal data from usb_host_endpoint both in add_endpoint and
drop_endpoint callbacks. But when setup packet was retired by
transaction errors in xhci_setup_device() path, a virt_dev for the slot
is newly created with real_port 0. This leads to xhci-mtks's NULL pointer
dereference from drop_endpoint callback as xhci-mtk assumes that virt_dev's
real_port is always started from one. The similar problems were addressed
by [1] but that can't cover the failure cases from setup_device.

This patch drops the usages of xhci's virt_dev in xhci-mtk's drop_endpoint
callback by adopting hashtable for searching mtk's schedule entity
from a given usb_host_endpoint pointer instead of searching a linked list.
So mtk's drop_endpoint callback doesn't have to rely on virt_dev at all.

[1] f351f4b63dac ("usb: xhci-mtk: fix oops when unbind driver")

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210826025144.51992-5-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add a member of num_esit

Add a member num_esit to save the number of esit, then no need
caculate it in some functions.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1629189389-18779-8-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: support option to disable usb2 ports

Add support to disable specific usb2 host ports, it's useful when
a usb2 port is disabled on some platforms, but enabled on others
for the same SoC.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1629189389-18779-4-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Revert "usb: xhci-mtk: Do not use xhci's virt_dev in drop_endpoint"

I find the patch introduce some issues, e.g.
1. oops happens when xhci_gen_setup() failed, and hash is not init
but try to destroy it;
2. memory leakage happens when fail to insert ep, need free sch_ep,
or insert ep after insert int list;
3. memory leakage happens when fail to allocate sch_array, need destroy
rhashtable;
4. it's better to check ep->hcpriv when drop ep;

so prefer to revert this patch, and resend it after the issues are fixed.

This reverts commit b8731209958a1dffccc2888121f4c0280c990550.

Cc: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210820065913.64490-2-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: Do not use xhci's virt_dev in drop_endpoint

xhci-mtk depends on xhci's internal virt_dev when it retrieves its
internal data from usb_host_endpoint both in add_endpoint and
drop_endpoint callbacks. But when setup packet was retired by
transaction errors in xhci_setup_device() path, a virt_dev for the slot
is newly created with real_port 0. This leads to xhci-mtks's NULL pointer
dereference from drop_endpoint callback as xhci-mtk assumes that virt_dev's
real_port is always started from one. The similar problems were addressed
by [1] but that can't cover the failure cases from setup_device.

This patch drops the usages of xhci's virt_dev in xhci-mtk's drop_endpoint
callback by adopting rhashtable for searching mtk's schedule entity
from a given usb_host_endpoint pointer instead of searching a linked list.
So mtk's drop_endpoint callback doesn't have to rely on virt_dev at all.

[1] https://lore.kernel.org/r/1617179142-2681-2-git-send-email-chunfeng.yun@mediatek.com

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Link: https://lore.kernel.org/r/20210805133731.1.Icc0f080e75b1312692d4c7c7d25e7df9fe1a05c2@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: allow multiple Start-Split in a microframe

This patch is used to relax bandwidth schedule by allowing multiple
Start-Split in the same microframe.

Reviewed-and-Tested-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1623995165-25759-1-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: use bitfield instead of bool

Use bitfield instead of bool in struct

Refer to coding-style.rst 17) Using bool:
"If a structure has many true/false values, consider consolidating
them into a bitfield with 1 bit members, or using an appropriate
fixed width type, such as u8."

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20210507021127.54717-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: remove unused members

Now some members about phys and wakeup are not used anymore,
remove them.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1618031406-15347-5-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: use clock bulk to get clocks

Use clock bulk helpers to get/enable/disable clocks, meanwhile
make sys_ck optional, then will be easier to handle clocks.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1618031406-15347-4-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: support quirk to disable usb2 lpm

The xHCI driver support usb2 HW LPM by default, here add support
XHCI_HW_LPM_DISABLE quirk, then we can disable usb2 lpm when
need it.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1617181553-3503-4-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: support to build xhci-mtk-hcd.ko

Currently xhci-hcd.ko building depends on USB_XHCI_MTK, this
is not flexible for some cases. For example:
USB_XHCI_HCD is y, and USB_XHCI_MTK is m, then we can't
implement extended functions if only update xhci-mtk.ko
This patch is used to remove the dependence.

Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/0b62e21ddfacc1c2874726dd27ccab80c993f303.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add a member @speed in mu3h_sch_ep_info struct

This is used to drop parameter @udev for some functions,
meanwhile remove some unused @udev parameter.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/cda0833e44d6027cc8fdee1e29ce2b5b2a6ac03d.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: use clear type instead of void

Use struct usb_host_endpoint instead of void to declare
the member @ep of mu3h_sch_ep_info struct.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/e9790eb4b959f9f843433fa5048c76772cc59061.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: remove unnecessary members of mu3h_sch_tt struct

The members @usb_tt and @tt_port in mu3h_sch_tt struct
are not used after initialization, so can be removed

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/9afecc2411895a3c76658df26ebca1c961a39fbb.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: improve bandwidth scheduling with TT

When the USB headset is plug into an external hub, sometimes
can't set config due to not enough bandwidth, so need improve
LS/FS INT/ISOC bandwidth scheduling with TT.

Fixes: 54f6a8af3722 ("usb: xhci-mtk: skip dropping bandwidth of unchecked endpoints")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Yaqii Wu <yaqii.wu@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/2f30e81400a59afef5f8231c98149169c7520519.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: skip dropping bandwidth of unchecked endpoints

For those unchecked endpoints, we don't allocate bandwidth for
them, so no need free the bandwidth, otherwise will decrease
the allocated bandwidth.
Meanwhile use xhci_dbg() instead of dev_dbg() to print logs and
rename bw_ep_list_new as bw_ep_chk_list.

Fixes: 1d69f9d901ef ("usb: xhci-mtk: fix unreleased bandwidth data")
Cc: stable <stable@vger.kernel.org>
Reviewed-and-tested-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1612159064-28413-1-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: fix unreleased bandwidth data

xhci-mtk needs XHCI_MTK_HOST quirk functions in add_endpoint() and
drop_endpoint() to handle its own sw bandwidth management.

It stores bandwidth data into an internal table every time
add_endpoint() is called, and drops those in drop_endpoint().
But when bandwidth allocation fails at one endpoint, all earlier
allocation from the same interface could still remain at the table.

This patch moves bandwidth management codes to check_bandwidth() and
reset_bandwidth() path. To do so, this patch also adds those functions
to xhci_driver_overrides and lets mtk-xhci to release all failed
endpoints in reset_bandwidth() path.

Fixes: 08e469de87a2 ("usb: xhci-mtk: supports bandwidth scheduling with multi-TT")
Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Link: https://lore.kernel.org/r/20210113180444.v6.1.Id0d31b5f3ddf5e734d2ab11161ac5821921b1e1e@changeid
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: host: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header files related to USB host controller drivers.
For C header files Documentation/process/license-rules.rst
mandates C-like comments (opposed to C source files where
C++ style should be used).

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Link: https://lore.kernel.org/r/20200404092135.GA4522@nishad
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: Replace zero-length array with flexible-array member

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]

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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add an optional xhci_ck clock

Some SoCs may have an optional clock xhci_ck (125M or 200M), it
usually uses the same PLL as sys_ck, so support it.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/1566542425-20082-2-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: supports bandwidth scheduling with multi-TT

Supports LowSpeed and FullSpeed INT/ISOC bandwidth scheduling
with USB multi-TT

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: improve bandwidth scheduling

Mainly improve SuperSpeed ISOC bandwidth in last microframe,
and LowSpeed/FullSpeed IN INT/ISOC bandwidth in split and
idle microframes by introduing a bandwidth budget table;

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: supports remote wakeup for mt2712 with two xHCI IPs

The old way of usb wakeup only supports platform with single xHCI IP,
such as mt8173, but mt2712 has two xHCI IPs, so rebuild its flow and
supports the new glue layer of usb wakeup on mt2712 which is different
from mt8173.
Due to there is a hardware bug with the LINE STATE wakeup mode on
mt8173 which causes wakeup failure by low speed devices, and also
because IP SLEEP mode can cover all functions of LINE STATE mode,
it is unused in fact, and will not support it later, so remove it at
the same time.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: host: xhci: Remove redundant license text

Now that the SPDX tag is in all USB files, that identifies the license
in a specific and legally-defined manner. So the extra GPL text wording
can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: add SPDX identifiers to all remaining files in drivers/usb/

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the drivers/usb/ and include/linux/usb* files with the correct
SPDX license identifier based on the license text in the file itself.
The SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add optional mcu and dma bus clocks

There are mcu_bus and dma_bus clocks needed to be controlled by
driver on some SoCs, so add them as optional ones

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: remove dummy wakeup debounce clocks

The wakeup debounce clocks for each ports in fact are not
needed, so remove them.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: support option to disable usb3 ports

Add support to disable specific usb3 ports, it's useful when
usb3 phy is shared with PCIe or SATA, because we should disable
the corresponding usb3 port if the phy is used by PCIe or SATA.
Sometimes it's helpful to analyse and solve problems.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: add reference clock

usually, the reference clock comes from 26M oscillator directly,
but some SoCs are not, add it for compatibility.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: xhci-mtk: make IPPC register optional

Make IPPC register optional to support host side of dual-role mode,
due to it is moved into common glue layer for simplification.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xhci: mediatek: support MTK xHCI host controller

There some vendor quirks for MTK xhci host controller:
1. It defines some extra SW scheduling parameters for HW
to minimize the scheduling effort for synchronous and
interrupt endpoints. The parameters are put into reseved
DWs of slot context and endpoint context.
2. Its IMODI unit for Interrupter Moderation register is
8 times as much as that defined in xHCI spec.
3. Its TDS in Normal TRB defines a number of packets that
remains to be transferred for a TD after processing all
Max packets in all previous TRBs.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>