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

Anup Patel
2023-11-23T10:43:52Z

On Wed, Nov 22, 2023 at 4:11 AM Samuel Holland
<samuel.holland@sifive.com> wrote:
>
> 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.

In which case, we need extend sbi_debug_console_write() to
do the va-to-pa conversion for both earlycon-riscv-sbi.c and
hvc_riscv_sbi.c

>
> > +}
> > +
> > 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.

Okay, I will update.

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

Regards,
Anup