Re: [PATCH RFC 07/10] tty: serial: Add Cortina Systems CS75xx UART driver

[Arnd Bergmann]

On Wed, Sep 30, 2026, at 13:24, Fil Dunsky wrote:
> On Wed, Sep 30, 2026 at 01:08:07PM +0200, Arnd Bergmann wrote:
>> On Wed, Sep 30, 2026, at 12:57, Linus Walleij wrote:
>>> Look at this in your Linux tree:
>>> git log -p b61c8bf4694b5115766849378dcb8787ff54e65e
>>>
>>> This is essentially a resurrection of that driver.
>>
>> Jason actually came back this summer to try again, see
>> https://lore.kernel.org/linux-arm-kernel/20260610112821.3030099-1-jason.li@xxxxxxxxxxxxxxxxxx/
>
> Thanks, I was not aware of either. Comparing the two, it is the same
> IP: the offsets of CFG, RX_SAMPLE, TX_DAT, RX_DAT, INFO, IE and INT
> and the bit layout of CFG, INFO and the interrupt registers are
> identical. The Cortina Access version additionally has a flow control
> register at 0x04, RT_TUNE at 0x0c, STATUS at 0x2c and three more
> interrupt causes (break, RX underrun, TX overrun).

Ok, thanks for checking.

>>> Anyways, clearly this driver is not just for CS75xx so name it
>>> cortina-uart.c simply, and update symbols accordingly. Kconfig
>>> should be SERIAL_CORTINA etc.
>>
>> I think we clearly want a driver that works for both the Cortina
>> Systems CS75xx and the Cortina Access CA82xx, hopefully that
>> would also support the ones inbetween (CS80xx, CA81xx).
>
> Agreed. For v2 I will rename it to drivers/tty/serial/cortina-uart.c
> with SERIAL_CORTINA and SERIAL_CORTINA_CONSOLE, and name the binding
> so that it can take the other parts. I would keep SoC specific
> compatibles ("cortina,cs7542-uart", later e.g.
> "cortina-access,ca8289-uart"), so that the flow control and the extra
> interrupt causes can be enabled per compatible.

Sounds good. The important bit here is to ensure the structure can
work with both variants.

    Arnd