On Wed, Aug 17, 2016 at 08:14:42PM -0500, Rob Herring wrote: > Currently, devices attached via a UART are not well supported in the > kernel. The problem is the device support is done in tty line disciplines, > various platform drivers to handle some sideband, and in userspace with > utilities such as hciattach. > > There have been several attempts to improve support, but they suffer from > still being tied into the tty layer and/or abusing the platform bus. This > is a prototype to show creating a proper UART bus for UART devices. It is > tied into the serial core (really struct uart_port) below the tty layer > in order to use existing serial drivers. > > This is functional with minimal testing using the loopback driver and > pl011 (w/o DMA) UART under QEMU (modified to add a DT node for the slave > device). It still needs lots of work and polish. > > TODOs: > - Figure out the port locking. mutex plus spinlock plus refcounting? I'm > hoping all that complexity is from the tty layer and not needed here. It should be. > - Split out the controller for uart_ports into separate driver. Do we see > a need for controller drivers that are not standard serial drivers? What do you mean by "controller" drivers here? I didn't understand them in the code. > - Implement/test the removal paths > - Fix the receive callbacks for more than character at a time (i.e. DMA) > - Need better receive buffering than just a simple circular buffer or > perhaps a different receive interface (e.g. direct to client buffer)? Why? Is the code as-is slow? > - Test with other UART drivers > - Convert a real driver/line discipline over to UART bus. That's going to be the real test, I recommend trying that as soon as possible as it will show where the real pain points are :) > Before I spend more time on this, I'm looking mainly for feedback on the > general direction and structure (the interface with the existing serial > drivers in particular). Yes, I like the idea (minor nit, you still have SPMI in a lot of places instead of UART), so I recommend keeping going with it. > drivers/uart/Kconfig | 17 ++ > drivers/uart/Makefile | 3 + > drivers/uart/core.c | 458 +++++++++++++++++++++++++++++++++++++++ > drivers/uart/loopback.c | 72 ++++++ Why not just put this in drivers/tty/uart/ ? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
