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[222.224.229.1]) by smtp.gmail.com with ESMTPSA id o7sm5548265pgs.45.2021.05.17.01.23.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 May 2021 01:23:06 -0700 (PDT) Date: Mon, 17 May 2021 17:23:04 +0900 From: Stafford Horne To: Jiri Slaby Cc: LKML , Florent Kermarrec , Mateusz Holenko , Joel Stanley , "Gabriel L . Somlo" , Jonathan Corbet , Greg Kroah-Hartman , Karol Gugala , "Paul E. McKenney" , Randy Dunlap , Andrew Morton , Thomas Gleixner , Viresh Kumar , Mike Kravetz , Peter Zijlstra , linux-doc@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH] serial/liteuart; Add support for earlycon Message-ID: References: <20210515084519.167343-1-shorne@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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 > > Cc: Florent Kermarrec > > Cc: Mateusz Holenko > > Cc: Joel Stanley > > Cc: Gabriel L. Somlo > > --- > > .../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, > > + 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, > > 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