Re: [PATCH v4 3/5] tty/serial: Add RISC-V SBI debug console based earlycon

Samuel Holland
2023-11-21T22:41:38Z

Hi Anup,

On 2023-11-17 9:38 PM, Anup Patel wrote:
> We extend the existing RISC-V SBI earlycon support to use the new
> RISC-V SBI debug console extension.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
> drivers/tty/serial/Kconfig | 2 +-
> drivers/tty/serial/earlycon-riscv-sbi.c | 24 ++++++++++++++++++++----
> 2 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 732c893c8d16..1f2594b8ab9d 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST
>
> config SERIAL_EARLYCON_RISCV_SBI
> bool "Early console using RISC-V SBI"
> - depends on RISCV_SBI_V01
> + depends on RISCV_SBI
> select SERIAL_CORE
> select SERIAL_CORE_CONSOLE
> select SERIAL_EARLYCON
> diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
> index 27afb0b74ea7..5351e1e31f45 100644
> --- a/drivers/tty/serial/earlycon-riscv-sbi.c
> +++ b/drivers/tty/serial/earlycon-riscv-sbi.c
> @@ -15,17 +15,33 @@ static void sbi_putc(struct uart_port *port, unsigned char c)
> sbi_console_putchar(c);
> }
>
> -static void sbi_console_write(struct console *con,
> - const char *s, unsigned n)
> +static void sbi_0_1_console_write(struct console *con,
> + const char *s, unsigned int n)
> {
> struct earlycon_device *dev = con->data;
> uart_console_write(&dev->port, s, n, sbi_putc);
> }
>
> +static void sbi_dbcn_console_write(struct console *con,
> + const char *s, unsigned int n)
> +{
> + sbi_debug_console_write(n, __pa(s));

This only works for strings in the linear mapping or the kernel mapping (not
vmalloc, which includes the stack). So I don't think we can use __pa() here.

> +}
> +
> static int __init early_sbi_setup(struct earlycon_device *device,
> const char *opt)
> {
> - device->con->write = sbi_console_write;
> - return 0;
> + int ret = 0;
> +
> + if (sbi_debug_console_available) {
> + device->con->write = sbi_dbcn_console_write;
> + } else {
> + if (IS_ENABLED(CONFIG_RISCV_SBI_V01))

"else if", no need for the extra block/indentation.

Regards,
Samuel

> + device->con->write = sbi_0_1_console_write;
> + else
> + ret = -ENODEV;
> + }
> +
> + return ret;
> }
> EARLYCON_DECLARE(sbi, early_sbi_setup);