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Commit 0d3c673e authored by Rob Herring's avatar Rob Herring Committed by Greg Kroah-Hartman
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tty/serial: pl011: add generic earlycon support 



Add earlycon support for the pl011 serial port. This allows enabling
the pl011 for console when early_params are processed. This is based
on the arm64 earlyprintk support and is intended to replace it.

Signed-off-by: default avatarRob Herring <robh@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d2fd6810

Documentation/kernel-parameters.txt

+7 −0
Original line number Diff line number Diff line
@@ -883,6 +883,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			which are not unmapped.



	earlycon=	[KNL] Output early console device and options.



		uart[8250],io,<addr>[,options]

		uart[8250],mmio,<addr>[,options]

		uart[8250],mmio32,<addr>[,options]
@@ -892,6 +893,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			(mmio) or 32-bit (mmio32).

			The options are the same as for ttyS, above.



		pl011,<addr>

			Start an early, polled-mode console on a pl011 serial

			port at the specified address. The pl011 serial port

			must already be setup and configured. Options are not

			yet supported.



	earlyprintk=	[X86,SH,BLACKFIN,ARM]

			earlyprintk=vga

			earlyprintk=efi

drivers/tty/serial/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ config SERIAL_AMBA_PL011_CONSOLE 
	bool "Support for console on AMBA serial port"

	depends on SERIAL_AMBA_PL011=y

	select SERIAL_CORE_CONSOLE

	select SERIAL_EARLYCON

	---help---

	  Say Y here if you wish to use an AMBA PrimeCell UART as the system

	  console (the system console is the device which receives all kernel

drivers/tty/serial/amba-pl011.c

+29 −1
Original line number Diff line number Diff line
@@ -2045,6 +2045,34 @@ static struct console amba_console = { 
};



#define AMBA_CONSOLE	(&amba_console)



static void pl011_putc(struct uart_port *port, int c)

{

	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)

		;

	writeb(c, port->membase + UART01x_DR);

	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)

		;

}



static void pl011_early_write(struct console *con, const char *s, unsigned n)

{

	struct earlycon_device *dev = con->data;



	uart_console_write(&dev->port, s, n, pl011_putc);

}



static int __init pl011_early_console_setup(struct earlycon_device *device,

					    const char *opt)

{

	if (!device->port.membase)

		return -ENODEV;



	device->con->write = pl011_early_write;

	return 0;

}

EARLYCON_DECLARE(pl011, pl011_early_console_setup);



#else

#define AMBA_CONSOLE	NULL

#endif