Add support for CDC ACM using the new UDC and gadget API. This protocol
can be used for serial over USB data transfer and is widely supported
by various OS (GNU/Linux, MS-Windows, OSX...). The usual purpose of
such link is to access device debug console and can be useful for
products not exposing regular UART to the user.

A default stdio device named 'usbacm' is created, and can be used
to redirect console to USB link over CDC ACM:

> setenv stdin usbacm; setenv stdout usbacm

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Let's deduplicate existing copies by splitting off to a new helper.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Nobody is using stdio_deregister(), remove for good.

Note, even its parameters are not consistent with stdio_register().
So, if anyone want to introduce this again, better with some consistency.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Bring the coding style in this file up to the current level.

Signed-off-by: Simon Glass <sjg@chromium.org>

These prevent the use of IS_ENABLED() and are unnecessary. Drop them and
fix a few code-style nits nearby.

Signed-off-by: Simon Glass <sjg@chromium.org>

When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>

With tighter build flags the fact that <stdio_dev.h> doesn't have a
reference back to MAX_NAMES causes an error.  Include <stdio.h> here and
then in common/console.c use MAX_NAMES rather than 3 when working with
stdio_names.

Reported-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>

With tighter build flags the fact that this header referenced
uchar/ushort without including what typedefs it causes an error.  Rather
than add another include here, drop the section in question as it is
unused.

Reported-by: Peter Robinson <pbrobinson@gmail.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>

With driver model the serial device is often not called "serial". Mark
driver-model stdio devices so that they can be detected and we can look up
the uclass. This is a more reliable way of finding out whether the console
is connected to a serial device or not.

Signed-off-by: Simon Glass <sjg@chromium.org>

This converts the following to Kconfig:
   CONFIG_SYS_STDIO_DEREGISTER

This option should never be enabled in SPL, so use
CONFIG_IS_ENABLED(SYS_STDIO_DEREGISTER) when checking the option.

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Re-sync]
Signed-off-by: Tom Rini <trini@konsulko.com>