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7cd93b89 YY |
1 | /* |
2 | * 8250/16550-type serial ports prom_putchar() | |
3 | * | |
4 | * Copyright (C) 2010 Yoichi Yuasa <yuasa@linux-mips.org> | |
5 | * | |
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. | |
10 | * | |
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. | |
15 | * | |
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 | |
19 | */ | |
20 | #include <linux/io.h> | |
21 | #include <linux/serial_core.h> | |
22 | #include <linux/serial_reg.h> | |
23 | ||
24 | static void __iomem *serial8250_base; | |
25 | static unsigned int serial8250_reg_shift; | |
26 | static unsigned int serial8250_tx_timeout; | |
27 | ||
28 | void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift, | |
29 | unsigned int timeout) | |
30 | { | |
31 | serial8250_base = (void __iomem *)base; | |
32 | serial8250_reg_shift = reg_shift; | |
33 | serial8250_tx_timeout = timeout; | |
34 | } | |
35 | ||
36 | static inline u8 serial_in(int offset) | |
37 | { | |
38 | return readb(serial8250_base + (offset << serial8250_reg_shift)); | |
39 | } | |
40 | ||
41 | static inline void serial_out(int offset, char value) | |
42 | { | |
43 | writeb(value, serial8250_base + (offset << serial8250_reg_shift)); | |
44 | } | |
45 | ||
46 | void prom_putchar(char c) | |
47 | { | |
48 | unsigned int timeout; | |
49 | int status, bits; | |
50 | ||
51 | if (!serial8250_base) | |
52 | return; | |
53 | ||
54 | timeout = serial8250_tx_timeout; | |
55 | bits = UART_LSR_TEMT | UART_LSR_THRE; | |
56 | ||
57 | do { | |
58 | status = serial_in(UART_LSR); | |
59 | ||
60 | if (--timeout == 0) | |
61 | break; | |
62 | } while ((status & bits) != bits); | |
63 | ||
64 | if (timeout) | |
65 | serial_out(UART_TX, c); | |
66 | } |