Any read materials to understand uart device driver architecture in FreeBSD.

[blubee blubeeme]

On Fri, Jul 13, 2018, 16:57 Rajesh Kumar <rajfbsd at gmail.com> wrote:

> Hi,
>
> I am trying to understand the uart device drivers architecture in FreeBSD.
> I see the following set of file in sys/dev/uart.
>
> a) uart_bus_xxxx -> one file each for acpi, pci, isa bus etc.,
> b) uart_core - uart common routines
> c) uart_cpu_xxxx -> one file each for x86, powerpc etc.,
> d) uart_dev_xxxx -> I assume this is one file each for seperate uart IP's.
> e) some other files.
>
> Questions :
> a) Is there any good read materials to understand the uart driver
> architecutre (from code perspective) in FreeBSD?
> b) If I need to write a new uart driver for a uart IP, what are the things
> to do? I assume i need to have a seperate uart_dev_* file and need to add
> that device ID in appropriate uart_bus_* file? what other things I need to
> take care?
> c) In uart_bus_acpi.c and uart_bus_isa.c, I see the definitions of
> acpi_ns8250_ids and isa_ns8250_ids list.  Where are those ID's derived
> from? I understand PNP ID, ACPI ID and PCI Vendor and Device ID, but not
> sure about those above mentioned IDs?
>
> Thanks,
> Rajesh.
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Writing drivers: https://nostarch.com/bsddrivers.htm

FreeBSD architecture:
https://www.amazon.com/Design-Implementation-FreeBSD-Operating-System/dp/0321968972

>