2 * 8250/16550-type serial ports prom_putchar()
4 * Copyright (C) 2010 Yoichi Yuasa <yuasa@linux-mips.org>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include <linux/serial_core.h>
22 #include <linux/serial_reg.h>
23 #include <asm/setup.h>
25 static void __iomem *serial8250_base;
26 static unsigned int serial8250_reg_shift;
27 static unsigned int serial8250_tx_timeout;
29 void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift,
32 serial8250_base = (void __iomem *)base;
33 serial8250_reg_shift = reg_shift;
34 serial8250_tx_timeout = timeout;
37 static inline u8 serial_in(int offset)
39 return readb(serial8250_base + (offset << serial8250_reg_shift));
42 static inline void serial_out(int offset, char value)
44 writeb(value, serial8250_base + (offset << serial8250_reg_shift));
47 void prom_putchar(char c)
55 timeout = serial8250_tx_timeout;
56 bits = UART_LSR_TEMT | UART_LSR_THRE;
59 status = serial_in(UART_LSR);
63 } while ((status & bits) != bits);
66 serial_out(UART_TX, c);