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Message-ID: <8c0f4eba-1923-4686-b07b-1f3b78b298e9@sifive.com>
Date:   Tue, 21 Nov 2023 16:41:26 -0600
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User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v4 3/5] tty/serial: Add RISC-V SBI debug console based
 earlycon
Content-Language: en-US
To:     Anup Patel <apatel@ventanamicro.com>
Cc:     Conor Dooley <conor@kernel.org>,
        Andrew Jones <ajones@ventanamicro.com>,
        linux-riscv@lists.infradead.org, linux-serial@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>
References: <20231118033859.726692-1-apatel@ventanamicro.com>
 <20231118033859.726692-4-apatel@ventanamicro.com>
From:   Samuel Holland <samuel.holland@sifive.com>
In-Reply-To: <20231118033859.726692-4-apatel@ventanamicro.com>
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Precedence: bulk

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);