Hi Jiri
is there something else that I am missing here?
Thanks!
On Thu, 24 Nov 2022 at 13:39, Ricardo Ribalda <ribalda@xxxxxxxxxxxx> wrote:
>
> Some platforms, namely AMD Picasso, use non standard uart clocks (48M),
> witch makes it impossible to use with earlycon.
>
> Let the user select its own frequency.
>
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a465d5242774..9efb6c3b0486 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1182,10 +1182,10 @@
> specified, the serial port must already be setup and
> configured.
>
> - uart[8250],io,<addr>[,options]
> - uart[8250],mmio,<addr>[,options]
> - uart[8250],mmio32,<addr>[,options]
> - uart[8250],mmio32be,<addr>[,options]
> + uart[8250],io,<addr>[,options[,uartclk]]
> + uart[8250],mmio,<addr>[,options[,uartclk]]
> + uart[8250],mmio32,<addr>[,options[,uartclk]]
> + uart[8250],mmio32be,<addr>[,options[,uartclk]]
> uart[8250],0x<addr>[,options]
> Start an early, polled-mode console on the 8250/16550
> UART at the specified I/O port or MMIO address.
> @@ -1194,7 +1194,9 @@
> If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
> to be equivalent to 'mmio'. 'options' are specified
> in the same format described for "console=ttyS<n>"; if
> - unspecified, the h/w is not initialized.
> + unspecified, the h/w is not initialized. 'uartclk' is
> + the uart clock frequency; if unspecified, it is set
> + to 'BASE_BAUD' * 16.
>
> pl011,<addr>
> pl011,mmio32,<addr>
> diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> index a5f380584cda..3a0c88419b6c 100644
> --- a/drivers/tty/serial/earlycon.c
> +++ b/drivers/tty/serial/earlycon.c
> @@ -120,7 +120,13 @@ static int __init parse_options(struct earlycon_device *device, char *options)
> }
>
> if (options) {
> + char *uartclk;
> +
> device->baud = simple_strtoul(options, NULL, 0);
> + uartclk = strchr(options, ',');
> + if (uartclk && kstrtouint(uartclk + 1, 0, &port->uartclk) < 0)
> + pr_warn("[%s] unsupported earlycon uart clkrate option\n",
> + options);
> length = min(strcspn(options, " ") + 1,
> (size_t)(sizeof(device->options)));
> strscpy(device->options, options, length);
> @@ -139,7 +145,8 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
> buf = NULL;
>
> spin_lock_init(&port->lock);
> - port->uartclk = BASE_BAUD * 16;
> + if (!port->uartclk)
> + port->uartclk = BASE_BAUD * 16;
> if (port->mapbase)
> port->membase = earlycon_map(port->mapbase, 64);
>
>
> --
> b4 0.11.0-dev-d93f8
--
Ricardo Ribalda
