Commit d1a1af2c authored by Michal Simek's avatar Michal Simek Committed by Greg Kroah-Hartman
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hvc: dcc: Add earlycon support 



Add DCC earlycon support for early printks. The patch is useful for SoC
bringup where HW serial console is broken.

Signed-off-by: default avatarMichal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/41e2920a6348e65b2e986b0e65b66531e87cd756.1570543923.git.michal.simek@xilinx.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 33364d63

drivers/tty/hvc/hvc_dcc.c

+28 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved.  */



#include <linux/console.h>

#include <linux/init.h>

#include <linux/serial.h>

#include <linux/serial_core.h>



#include <asm/dcc.h>

#include <asm/processor.h>
@@ -12,6 +15,31 @@ 
#define DCC_STATUS_RX		(1 << 30)

#define DCC_STATUS_TX		(1 << 29)



static void dcc_uart_console_putchar(struct uart_port *port, int ch)

{

	while (__dcc_getstatus() & DCC_STATUS_TX)

		cpu_relax();



	__dcc_putchar(ch);

}



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

{

	struct earlycon_device *dev = con->data;



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

}



static int __init dcc_early_console_setup(struct earlycon_device *device,

					  const char *opt)

{

	device->con->write = dcc_early_write;



	return 0;

}



EARLYCON_DECLARE(dcc, dcc_early_console_setup);



static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)

{

	int i;