7678f4c20f
On DT platforms, the sh-sci driver requires the presence of "serialN" aliases in DT, from which instance IDs are derived. If a DT alias is missing, the drivers fails to probe the corresponding serial port. This becomes cumbersome when considering DT overlays, as currently there is no upstream support for dynamically updating the /aliases node in DT. Furthermore, even in the presence of such support, hardcoded instance IDs in independent overlays are prone to conflicts. Hence add support for dynamic instance IDs, to be used in the absence of a DT alias. This makes serial ports behave similar to I2C and SPI buses, which already support dynamic instances. Ports in use are tracked using a simple bitmask of type unsigned long, which is sufficient to handle all current hardware (max. 18 ports). The maximum number of serial ports is still fixed, and configurable through Kconfig. Range validation is done through both Kconfig and a compile-time check. Due to the fixed maximum number of serial ports, dynamic and static instances share the same ID space. Static instances added later are rejected when conflicting with dynamic instances registered earlier. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.