Now that the driver core can properly handle constant struct bus_type,
move all of the USB subsystem struct bus_type structures as const,
placing them into read-only memory which can not be modified at runtime.

Cc: Johan Hovold <johan@kernel.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: linux-usb@vger.kernel.org
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230313182918.1312597-36-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Just like it does with muxes, the Type-C bus code can update the state
of connected retimers (especially when altmode-related transitions
occur). Add a retimer handle to the port altmode struct to enable this.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230112221609.540754-2-pmalani@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Adding a header file for each subsystem - the connector
class, alt mode bus and the class for the muxes.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210401105847.13026-2-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Using the generic notification chain is not reasonable with
the alternate modes because it would require dependencies
between the drivers of the components that need the
notifications, and the typec drivers.

There are no users for the alternate mode notifications, so
removing the chain and the API for it completely.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200211112531.86510-6-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Registering real device entries (struct device) for the mode
muxes as well as for the orientation switches.

The Type-C mux code was deliberately attempting to avoid
creation of separate device entries for the orientation
switch and the mode switch (alternate modes) because they
are not physical devices. They are functions of a single
physical multiplexer/demultiplexer switch device.

Unfortunately because of the dependency we still have on the
underlying mux device driver, we had to put in hacks like
the one in the commit 3e3b81965cbf ("usb: typec: mux: Take
care of driver module reference counting") to make sure the
driver does not disappear from underneath us. Even with
those hacks we were still left with a potential NUll pointer
dereference scenario, so just creating the device entries,
and letting the core take care of the dependencies. No more
hacks needed.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

gcc-8 points out that the fix-byte buffer might be too small if
desc->mode is a three-digit number:

drivers/usb/typec/class.c: In function 'typec_register_altmode':
drivers/usb/typec/class.c:502:32: error: '%d' directive writing between 1 and 3 bytes into a region of size 2 [-Werror=format-overflow=]
  sprintf(alt->group_name, "mode%d", desc->mode);
                                ^~
drivers/usb/typec/class.c:502:27: note: directive argument in the range [0, 255]
  sprintf(alt->group_name, "mode%d", desc->mode);
                           ^~~~~~~~
drivers/usb/typec/class.c:502:2: note: 'sprintf' output between 6 and 8 bytes into a destination of size 6
  sprintf(alt->group_name, "mode%d", desc->mode);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I assume this cannot happen in practice, but we can simply make the
string long enough to avoid the warning. This uses the two padding
bytes that already exist after the string.

Fixes: 4ab8c18d4d67 ("usb: typec: Register a device for every mode")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Introducing a simple bus for the alternate modes. Bus allows
binding drivers to the discovered alternate modes the
partners support.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>