> Date: Fri, 24 Nov 2017 19:01:21 +0000 > From: Kevin Chadwick <[email protected]> > > I am looking into getting Intel HSUART/8250 LPSS support working. Has > anyone done any work on this out of tree. Or is there anything I should > be aware of.
This device is based on the same Synopsys Designware "IP" as what's found on many ARM SoCs. Pretty much com(4) compatible but with some twists. 1. The registers are wider. Instead of the traditional 1-byte registers it has 4-byte registers. On ARM we use a bus_space hack to get around this issue, but I don't think I want to advocate replicating that approach for amd64/i386. Abstracting the register access functions is probably the way to go. 2. There are additional registers. It seems that most of these can be ignored, but the USR register needs to be poked under some circumstances. See sys/arch/armv7/dev/conm_fdt.c. Also, are you looking at acpi attachment or straight PCI?
