usb: fotg210-hcd: Replace snprintf() with the safer scnprintf() variant

There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array. However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it. This misunderstanding has led to buffer-overruns
in the past. It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases). So let's
do that.

The uses in this file both seem to assume that data *has been* written!

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Yuan-Hsin Chen <yhchen@faraday-tech.com>
Cc: Feng-Hsin Chiang <john453@faraday-tech.com>
Cc: Po-Yu Chuang <ratbert.chuang@gmail.com>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20231130105459.3208986-4-lee@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210-hcd: delete an incorrect bounds test

Here "temp" is the number of characters that we have written and "size"
is the size of the buffer. The intent was clearly to say that if we have
written to the end of the buffer then stop.

However, for that to work the comparison should have been done on the
original "size" value instead of the "size -= temp" value. Not only
will that not trigger when we want to, but there is a small chance that
it will trigger incorrectly before we want it to and we break from the
loop slightly earlier than intended.

This code was recently changed from using snprintf() to scnprintf(). With
snprintf() we likely would have continued looping and passed a negative
size parameter to snprintf(). This would have triggered an annoying
WARN(). Now that we have converted to scnprintf() "size" will never
drop below 1 and there is no real need for this test. We could change
the condition to "if (temp <= 1) goto done;" but just deleting the test
is cleanest.

Fixes: 7d50195f6c50 ("usb: host: Faraday fotg210-hcd driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/ZXmwIwHe35wGfgzu@suswa
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

USB: fotg210: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230202153235.2412790-5-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210: Switch to use dev_err_probe()

Switch to use dev_err_probe() to simplify the error paths and
unify message template.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230120154437.22025-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210-hcd: Don't shadow error codes in store()

kstrtox() along with regmap API can return different error codes based on
circumstances.

Don't shadow them when returning to the caller.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230120154437.22025-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210-hcd: use sysfs_emit() to instead of scnprintf()

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230120154437.22025-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210: Move clock handling to core

Grab the optional silicon block clock, prepare and enable it in
the core before proceeding to prepare the host or peripheral
driver. This saves duplicate code and also uses the simple
devm_clk_get_optional_enabled() to do everything we really
want to do.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230103-gemini-fotg210-usb-v2-4-100388af9810@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210: Acquire memory resource in core

The subdrivers are obtaining and mapping the memory resource
separately. Create a common state container for the shared
resources and start populating this by acquiring the IO
memory resource and remap it and pass this to the subdrivers
for host and peripheral.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230103-gemini-fotg210-usb-v2-3-100388af9810@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210: Compile into one module

It is since ages perfectly possible to compile both of these
modules into the same kernel, which makes no sense since it
is one piece of hardware.

Compile one module named "fotg210.ko" for both HCD and UDC
drivers by collecting the init calls into a fotg210-core.c
file and start to centralize things handling one and the same
piece of hardware.

Stub out the initcalls if one or the other part of the driver
was not selected.

Tested by compiling one or the other or both of the drivers
into the kernel and as modules.

Cc: Fabian Vogt <fabian@ritter-vogt.de>
Cc: Yuan-Hsin Chen <yhchen@faraday-tech.com>
Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221023144708.3596563-2-linus.walleij@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: fotg210: Collect pieces of dual mode controller

The Faraday FOTG210 is a dual-mode OTG USB controller that can
act as host, peripheral or both. To be able to probe from one
hardware description and to follow the pattern of other dual-
mode controllers such as MUSB or MTU3 we need to collect the
two, currently completely separate drivers in the same
directory.

After this, users need to select the main symbol USB_FOTG210
and then each respective subdriver. We pave the road to
compile both drivers into the same kernel and select the
one we want to use at probe() time, and possibly add OTG
support in the end.

This patch doesn't do much more than create the new symbol
and collect the drivers in one place. We also add a comment
for the section of dual-mode controllers in the Kconfig
file so people can see what these selections are about.

Also add myself as maintainer as there has been little
response on my patches to these drivers.

Cc: Fabian Vogt <fabian@ritter-vogt.de>
Cc: Yuan-Hsin Chen <yhchen@faraday-tech.com>
Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221023144708.3596563-1-linus.walleij@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>