You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
66 lines
1.8 KiB
66 lines
1.8 KiB
/* |
|
* 8250/16550-type serial ports prom_putchar() |
|
* |
|
* Copyright (C) 2010 Yoichi Yuasa <yuasa@linux-mips.org> |
|
* |
|
* This program is free software; you can redistribute it and/or modify |
|
* it under the terms of the GNU General Public License as published by |
|
* the Free Software Foundation; either version 2 of the License, or |
|
* (at your option) any later version. |
|
* |
|
* 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, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
#include <linux/io.h> |
|
#include <linux/serial_core.h> |
|
#include <linux/serial_reg.h> |
|
|
|
static void __iomem *serial8250_base; |
|
static unsigned int serial8250_reg_shift; |
|
static unsigned int serial8250_tx_timeout; |
|
|
|
void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift, |
|
unsigned int timeout) |
|
{ |
|
serial8250_base = (void __iomem *)base; |
|
serial8250_reg_shift = reg_shift; |
|
serial8250_tx_timeout = timeout; |
|
} |
|
|
|
static inline u8 serial_in(int offset) |
|
{ |
|
return readb(serial8250_base + (offset << serial8250_reg_shift)); |
|
} |
|
|
|
static inline void serial_out(int offset, char value) |
|
{ |
|
writeb(value, serial8250_base + (offset << serial8250_reg_shift)); |
|
} |
|
|
|
void prom_putchar(char c) |
|
{ |
|
unsigned int timeout; |
|
int status, bits; |
|
|
|
if (!serial8250_base) |
|
return; |
|
|
|
timeout = serial8250_tx_timeout; |
|
bits = UART_LSR_TEMT | UART_LSR_THRE; |
|
|
|
do { |
|
status = serial_in(UART_LSR); |
|
|
|
if (--timeout == 0) |
|
break; |
|
} while ((status & bits) != bits); |
|
|
|
if (timeout) |
|
serial_out(UART_TX, c); |
|
}
|
|
|