d50d7269eb
Add earlycon support for the arm/arm64 semihosting debug serial interface. This allows enabling a debug console when early_params are processed. This is based on the arm64 earlyprintk smh support and is intended to replace it. Signed-off-by: Rob Herring <robh@kernel.org> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/*
|
|
* Copyright (C) 2012 ARM Ltd.
|
|
* Author: Marc Zyngier <marc.zyngier@arm.com>
|
|
*
|
|
* Adapted for ARM and earlycon:
|
|
* Copyright (C) 2014 Linaro Ltd.
|
|
* Author: Rob Herring <robh@kernel.org>
|
|
*
|
|
* This program is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/console.h>
|
|
#include <linux/init.h>
|
|
#include <linux/serial_core.h>
|
|
|
|
#ifdef CONFIG_THUMB2_KERNEL
|
|
#define SEMIHOST_SWI "0xab"
|
|
#else
|
|
#define SEMIHOST_SWI "0x123456"
|
|
#endif
|
|
|
|
/*
|
|
* Semihosting-based debug console
|
|
*/
|
|
static void smh_putc(struct uart_port *port, int c)
|
|
{
|
|
#ifdef CONFIG_ARM64
|
|
asm volatile("mov x1, %0\n"
|
|
"mov x0, #3\n"
|
|
"hlt 0xf000\n"
|
|
: : "r" (&c) : "x0", "x1", "memory");
|
|
#else
|
|
asm volatile("mov r1, %0\n"
|
|
"mov r0, #3\n"
|
|
"svc " SEMIHOST_SWI "\n"
|
|
: : "r" (&c) : "r0", "r1", "memory");
|
|
#endif
|
|
}
|
|
|
|
static void smh_write(struct console *con, const char *s, unsigned n)
|
|
{
|
|
struct earlycon_device *dev = con->data;
|
|
uart_console_write(&dev->port, s, n, smh_putc);
|
|
}
|
|
|
|
int __init early_smh_setup(struct earlycon_device *device, const char *opt)
|
|
{
|
|
device->con->write = smh_write;
|
|
return 0;
|
|
}
|
|
EARLYCON_DECLARE(smh, early_smh_setup);
|