On Mon, May 17, 2021 at 10:16:43AM +0200, Jiri Slaby wrote:
> On 15. 05. 21, 10:45, Stafford Horne wrote:
> > Most litex boards using RISC-V soft cores us the sbi earlycon, however
> > this is not available for non RISC-V litex SoC. This patch enables
> > earlycon for liteuart which is available on all Litex SoC's making
> > support for earycon debugging more widely available.
> >
> > Signed-off-by: Stafford Horne <shorne@xxxxxxxxx>
> > Cc: Florent Kermarrec <florent@xxxxxxxxxxxxxxxx>
> > Cc: Mateusz Holenko <mholenko@xxxxxxxxxxxx>
> > Cc: Joel Stanley <joel@xxxxxxxxx>
> > Cc: Gabriel L. Somlo <gsomlo@xxxxxxxxx>
> > ---
> > .../admin-guide/kernel-parameters.txt | 5 +++
> > drivers/tty/serial/Kconfig | 1 +
> > drivers/tty/serial/liteuart.c | 31 +++++++++++++++++++
> > 3 files changed, 37 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 04545725f187..2d4a43af8de2 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -1084,6 +1084,11 @@
> > the driver will use only 32-bit accessors to read/write
> > the device registers.
> > + liteuart,<addr>
> > + Start an early console on a litex serial port at the
> > + specified address. The serial port must already be
> > + setup and configured. Options are not yet supported.
> > +
> > meson,<addr>
> > Start an early, polled-mode console on a meson serial
> > port at the specified address. The serial port must
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index 0c4cd4a348f4..9ceffe6ab6fd 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -1531,6 +1531,7 @@ config SERIAL_LITEUART
> > depends on OF || COMPILE_TEST
> > depends on LITEX
> > select SERIAL_CORE
> > + select SERIAL_EARLYCON
> > help
> > This driver is for the FPGA-based LiteUART serial controller from LiteX
> > SoC builder.
> > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
> > index 64842f3539e1..38c472487e68 100644
> > --- a/drivers/tty/serial/liteuart.c
> > +++ b/drivers/tty/serial/liteuart.c
> > @@ -372,6 +372,37 @@ static int __init liteuart_console_init(void)
> > console_initcall(liteuart_console_init);
> > #endif /* CONFIG_SERIAL_LITEUART_CONSOLE */
> > +#ifdef CONFIG_SERIAL_EARLYCON
> > +static void early_liteuart_putc(struct uart_port *port, int c)
> > +{
> > + while (litex_read8(port->membase + OFF_TXFULL))
> > + cpu_relax();
> > +
> > + litex_write8(port->membase + OFF_RXTX, c);
>
> Hi,
>
> am I missing something or this doesn't differ to liteuart_putchar?
Hi, No you are right, I missed that thanks for catching it.
I should be able to remove this function and use putchar below.
-Stafford
> > +}
> > +
> > +static void early_liteuart_write(struct console *console, const char *s,
> > + unsigned int count)
> > +{
> > + struct earlycon_device *device = console->data;
> > + struct uart_port *port = &device->port;
> > +
> > + uart_console_write(port, s, count, early_liteuart_putc);
> > +}
> > +
> > +static int __init early_liteuart_setup(struct earlycon_device *device,
> > + const char *options)
> > +{
> > + if (!device->port.membase)
> > + return -ENODEV;
> > +
> > + device->con->write = early_liteuart_write;
> > + return 0;
> > +}
> > +
> > +OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup);
> > +#endif /* CONFIG_SERIAL_EARLYCON */
> > +
> > static int __init liteuart_init(void)
> > {
> > int res;
> >
>
>
> --
> js
> suse labs
