Re: [PATCH] serial: 8250: move mmp|pxa uart earlycon code and add xscale earlycon

Yixun Lan
2024-07-06T22:33:45Z

Hi
On 18:18 Sat 06 Jul , Jisheng Zhang wrote:
> There are two other drivers that bind to "mrvl,mmp-uart": the 8250_of
> and the 8250_pxa. The previous one is generic and the latter is binded
> to ARCH_PXA || ARCH_MMP. Now we may have pxa programming compatible
> HW to support, making use of the generic 8250_of seems a good idea.
> However, there's no earlycon support if we go with this solution. So
> move the mmp|pxa-uart earlycon code to core 8250_early.c.
>
> At the same, add xscale earlycon support too, only build test since
> I have no xscale machine any more.
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
> drivers/tty/serial/8250/8250_early.c | 11 +++++++++++
> drivers/tty/serial/8250/8250_pxa.c | 16 ----------------
> 2 files changed, 11 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
> index e3f482fd3de4..6176083d0341 100644
> --- a/drivers/tty/serial/8250/8250_early.c
> +++ b/drivers/tty/serial/8250/8250_early.c
> @@ -171,6 +171,17 @@ OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
> OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
> OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);
>
> +static int __init early_serial8250_rs2_setup(struct earlycon_device *device,
> + const char *options)
> +{
> + device->port.regshift = 2;
just wondering if possible to introduce a generic earlycon sub option? so kernel
can parse reg-shift from command line parameter instead of hardcoding here,
which would benefit more drivers (potentially without adding more OF_EARLYCON_DECLAREs..)

I mean something like this:
Documentation/admin-guide/kernel-parameters.txt
uart[8250],mmio32,<addr>[,options[,reg-shift=0,1,2,4 ..]]

> +
> + return early_serial8250_setup(device, options);
> +}
> +OF_EARLYCON_DECLARE(uart, "intel,xscale-uart", early_serial8250_rs2_setup);
> +OF_EARLYCON_DECLARE(uart, "mrvl,mmp-uart", early_serial8250_rs2_setup);
> +OF_EARLYCON_DECLARE(uart, "mrvl,pxa-uart", early_serial8250_rs2_setup);
> +
> #ifdef CONFIG_SERIAL_8250_OMAP
>
> static int __init early_omap8250_setup(struct earlycon_device *device,
> diff --git a/drivers/tty/serial/8250/8250_pxa.c b/drivers/tty/serial/8250/8250_pxa.c
> index ba96fa913e7f..b5d937f6f3f9 100644
> --- a/drivers/tty/serial/8250/8250_pxa.c
> +++ b/drivers/tty/serial/8250/8250_pxa.c
> @@ -165,22 +165,6 @@ static struct platform_driver serial_pxa_driver = {
>
> module_platform_driver(serial_pxa_driver);
>
> -#ifdef CONFIG_SERIAL_8250_CONSOLE
> -static int __init early_serial_pxa_setup(struct earlycon_device *device,
> - const char *options)
> -{
> - struct uart_port *port = &device->port;
> -
> - if (!(device->port.membase || device->port.iobase))
> - return -ENODEV;
> -
> - port->regshift = 2;
> - return early_serial8250_setup(device, NULL);
> -}
> -OF_EARLYCON_DECLARE(early_pxa, "mrvl,pxa-uart", early_serial_pxa_setup);
> -OF_EARLYCON_DECLARE(mmp, "mrvl,mmp-uart", early_serial_pxa_setup);
> -#endif
> -
> MODULE_AUTHOR("Sergei Ianovich");
> MODULE_LICENSE("GPL");
> MODULE_ALIAS("platform:pxa2xx-uart");
> --
> 2.43.0
>

--
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55