Re: [PATCH v3 1/2] dt-bindings: serial: 8250: add Microchip Core16550

From: Conor Dooley

Date: Tue Nov 10 2026 - 13:19:27 EST


On Tue, Nov 10, 2026 at 09:06:48AM +1100, Kohei Otsuka via B4 Relay wrote:
> From: Kohei Otsuka <kohei@xxxxxxxxxxxxxxxxx>
>
> Core16550 is a 16550-compatible UART soft IP core for Microchip FPGAs,
> including the fabric of PolarFire SoC. Its registers follow the 16550A,
> but it raises no interrupt on TEMT. A driver that knows only ns16550a
> waits for one in software RS-485 mode (em485), so RTS stays asserted
> after the first frame and the port stops receiving. ns16550a is
> therefore not a valid fallback.
>
> Add microchip,core16550-rtl-v3 as a compatible of its own. As for
> Microchip's other FPGA fabric cores, the -rtl-v3 suffix is the major
> RTL version of the IP, Core16550 3.x.
>
> Link: https://github.com/linux4microchip/meta-mchp/issues/5
> Signed-off-by: Kohei Otsuka <kohei@xxxxxxxxxxxxxxxxx>

With both dt-binding maintainer and microchip fpga hats on:
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
pw-bot: not-applicable

Thanks,
Conor.

> ---
> Documentation/devicetree/bindings/serial/8250.yaml | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/Documentation/devicetree/bindings/serial/8250.yaml b/Documentation/devicetree/bindings/serial/8250.yaml
> index 50d5c977afa3..d9ee14f7b694 100644
> --- a/Documentation/devicetree/bindings/serial/8250.yaml
> +++ b/Documentation/devicetree/bindings/serial/8250.yaml
> @@ -111,6 +111,7 @@ properties:
> - aspeed,ast2400-vuart
> - aspeed,ast2500-vuart
> - intel,xscale-uart
> + - microchip,core16550-rtl-v3
> - mrvl,pxa-uart
> - nuvoton,npcm750-uart
> - nuvoton,wpcm450-uart
>
> --
> 2.53.0
>
>
>

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