usb: dwc3: ulpi: Fix USB2.0 HS/FS/LS PHY suspend regression

First of all the commit e0082698b689 ("usb: dwc3: ulpi: conditionally
resume ULPI PHY") introduced the Suspend USB2.0 HS/FS/LS PHY regression,
as by design of the fix any attempt to read/write from/to the PHY control
registers will completely disable the PHY suspension, which consequently
will increase the USB bus power consumption. Secondly the fix won't work
well for the very first attempt of the ULPI PHY control registers IO,
because after disabling the USB2.0 PHY suspension functionality it will
still take some time for the bus to resume from the sleep state if one has
been reached before it. So the very first PHY register read/write
operation will take more time than the busy-loop provides and the IO
timeout error might be returned anyway.

Here we suggest to fix the denoted problems in the following way. First of
all let's not disable the Suspend USB2.0 HS/FS/LS PHY functionality so to
make the controller and the USB2.0 bus more power efficient. Secondly
instead of that we'll extend the PHY IO op wait procedure with 1 - 1.2 ms
sleep if the PHY suspension is enabled (1ms should be enough as by LPM
specification it is at most how long it takes for the USB2.0 bus to resume
from L1 (Sleep) state). Finally in case if the USB2.0 PHY suspension
functionality has been disabled on the DWC USB3 controller setup procedure
we'll compensate the USB bus resume process latency by extending the
busy-loop attempts counter.

Fixes: e0082698b689 ("usb: dwc3: ulpi: conditionally resume ULPI PHY")
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210085008.13264-4-Sergey.Semin@baikalelectronics.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: dwc3: ulpi: Replace CPU-based busyloop with Protocol-based one

Originally the procedure of the ULPI transaction finish detection has been
developed as a simple busy-loop with just decrementing counter and no
delays. It's wrong since on different systems the loop will take a
different time to complete. So if the system bus and CPU are fast enough
to overtake the ULPI bus and the companion PHY reaction, then we'll get to
take a false timeout error. Fix this by converting the busy-loop procedure
to take the standard bus speed, address value and the registers access
mode into account for the busy-loop delay calculation.

Here is the way the fix works. It's known that the ULPI bus is clocked
with 60MHz signal. In accordance with [1] the ULPI bus protocol is created
so to spend 5 and 6 clock periods for immediate register write and read
operations respectively, and 6 and 7 clock periods - for the extended
register writes and reads. Based on that we can easily pre-calculate the
time which will be needed for the controller to perform a requested IO
operation. Note we'll still preserve the attempts counter in case if the
DWC USB3 controller has got some internals delays.

[1] UTMI+ Low Pin Interface (ULPI) Specification, Revision 1.1,
October 20, 2004, pp. 30 - 36.

Fixes: 88bc9d194ff6 ("usb: dwc3: add ULPI interface support")
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210085008.13264-3-Sergey.Semin@baikalelectronics.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: dwc3: ulpi: Use VStsDone to detect PHY regs access completion

In accordance with [1] the DWC_usb3 core sets the GUSB2PHYACCn.VStsDone
bit when the PHY vendor control access is done and clears it when the
application initiates a new transaction. The doc doesn't say anything
about the GUSB2PHYACCn.VStsBsy flag serving for the same purpose. Moreover
we've discovered that the VStsBsy flag can be cleared before the VStsDone
bit. So using the former as a signal of the PHY control registers
completion might be dangerous. Let's have the VStsDone flag utilized
instead then.

[1] Synopsys DesignWare Cores SuperSpeed USB 3.0 xHCI Host Controller
Databook, 2.70a, December 2013, p.388

Fixes: 88bc9d194ff6 ("usb: dwc3: add ULPI interface support")
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210085008.13264-2-Sergey.Semin@baikalelectronics.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: dwc3: ulpi: fix checkpatch warning

no functional changes.

Signed-off-by: Felipe Balbi <balbi@kernel.org>

usb: dwc3: ulpi: File headers are not doc headers

Demote ulpi.c's file header to a standard comment block.

Fixes the following W=1 build warning:

drivers/usb/dwc3/ulpi.c:18: warning: Function parameter or member 'a' not described in 'DWC3_ULPI_ADDR'

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200702144625.2533530-7-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: dwc3: 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: Kukjin Kim <kgene@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Patrice Chotard <patrice.chotard@st.com>
Acked-by: Felipe Balbi <felipe.balbi@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: dwc3: ulpi: conditionally resume ULPI PHY

If PHY is suspended by the time we want to issue ULPI transfers, we
will observe timeouts on the ULPI interface. In order to avoid such
issue, let's make sure PHY is resumed before issuing a ULPI transfer.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: dwc3: ulpi: make dwc3_ulpi_ops constant

ulpi_register_interface() accepts a const struct ulpi_ops and dwc3
doesn't perform any changes to this struct at runtime, so there's no
reason it shouldn't be constant.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: ulpi: rename operations {read|write}_dev to simply {read|write}

With the removal of the old {read|write} operations, we can now safely
rename the new api operations {read|write}_dev to use the shorter and
clearer names {read|write}, respectively.

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: dwc3: ulpi: use new api

The old read, write callbacks in struct ulpi_ops have been deprecated
in favor of new callbacks that pass the parent device directly.
Replace the used callbacks in dwc3's ulpi component with the new api.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

usb: dwc3: add ULPI interface support

Registers DWC3's ULPI interface with the ULPI bus when it's
available.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>