1 /* $Id: serial.h,v 1.2 2000/01/17 23:32:47 ralf Exp $
2 *
3 * This file is subject to the terms and conditions of the GNU General Public
4 * License. See the file "COPYING" in the main directory of this archive
5 * for more details.
6 *
7 * Copyright (C) 1999 by Ralf Baechle
8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9 */
10 #ifndef _ASM_SERIAL_H
11 #define _ASM_SERIAL_H
12
13 /*
14 * This assumes you have a 1.8432 MHz clock for your UART.
15 *
16 * It'd be nice if someone built a serial card with a 24.576 MHz
17 * clock, since the 16550A is capable of handling a top speed of 1.5
18 * megabits/second; but this requires the faster clock.
19 */
20 #define BASE_BAUD (1843200 / 16)
21
22 /*
23 * Note about serial ports and consoles:
24 * For console output, everyone uses the IOC3 UARTA (offset 0x178)
25 * connected to the master node (look in ip27_setup_console() and
26 * ip27prom_console_write()).
27 *
28 * For serial (/dev/ttyS0 etc), we can not have hardcoded serial port
29 * addresses on a partitioned machine. Since we currently use the ioc3
30 * serial ports, we use dynamic serial port discovery that the serial.c
31 * driver uses for pci/pnp ports (there is an entry for the SGI ioc3
32 * boards in pci_boards[]). Unfortunately, UARTA's pio address is greater
33 * than UARTB's, although UARTA on o200s has traditionally been known as
34 * port 0. So, we just use one serial port from each ioc3 (since the
35 * serial driver adds addresses to get to higher ports).
36 *
37 * The first one to do a register_console becomes the preferred console
38 * (if there is no kernel command line console= directive). /dev/console
39 * (ie 5, 1) is then "aliased" into the device number returned by the
40 * "device" routine referred to in this console structure
41 * (ip27prom_console_dev).
42 *
43 * Also look in ip27-pci.c:pci_fixuop_ioc3() for some comments on working
44 * around ioc3 oddities in this respect.
45 *
46 * The IOC3 serials use a 22MHz clock rate with an additional divider by 3.
47 * (IOC3_BAUD = (22000000 / (3*16)))
48 */
49
50 #define RS_TABLE_SIZE 64
51
52 #define SERIAL_PORT_DFNS
53
54 #endif /* _ASM_SERIAL_H */
55
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