SERDEV "Serial Device Bus" Added To Linux 4.11 Kernel

The TTY/serial patches were mailed in earlier this week by Greg KH for the Linux 4.11 kernel merge window. Normally this isn't a pull request with much interest from us as it's generally not too interesting, but this time around it introduces a new bus.

The SERDEV is being added as the "serial device bus" for the Linux kernel. While this serial device bus is being added for Linux 4.11, there aren't any drivers actually making use of it in Linux 4.11 but that's expected to happen in Linux 4.12, potentially affecting Bluetooth.

Rob Herring who has been spearheading this serial bus work describes it as:

The serdev bus is designed for devices such as Bluetooth, WiFi, GPS and NFC connected to UARTs on host processors. Tradionally these have been handled with tty line disciplines, rfkill, and userspace glue such as hciattach. This approach has many drawbacks since it doesn't fit into the Linux driver model. Handling of sideband signals, power control and firmware loading are the main issues.

This creates a serdev bus with controllers (i.e. host serial ports) and attached devices. Typically, these are point to point connections, but some devices have muxing protocols or a h/w mux is conceivable. Any muxing is not yet supported with the serdev bus.

More details via the TTY/serial pull request.