xref: /openbmc/linux/arch/mips/kernel/csrc-ioasic.c (revision 22246614)
1 /*
2  *  DEC I/O ASIC's counter clocksource
3  *
4  *  Copyright (C) 2008  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
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/clocksource.h>
21 #include <linux/init.h>
22 
23 #include <asm/ds1287.h>
24 #include <asm/time.h>
25 #include <asm/dec/ioasic.h>
26 #include <asm/dec/ioasic_addrs.h>
27 
28 static cycle_t dec_ioasic_hpt_read(void)
29 {
30 	return ioasic_read(IO_REG_FCTR);
31 }
32 
33 static struct clocksource clocksource_dec = {
34 	.name		= "dec-ioasic",
35 	.read		= dec_ioasic_hpt_read,
36 	.mask		= CLOCKSOURCE_MASK(32),
37 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
38 };
39 
40 void __init dec_ioasic_clocksource_init(void)
41 {
42 	unsigned int freq;
43 	u32 start, end;
44 	int i = HZ / 10;
45 
46 
47 	while (!ds1287_timer_state())
48 		;
49 
50 	start = dec_ioasic_hpt_read();
51 
52 	while (i--)
53 		while (!ds1287_timer_state())
54 			;
55 
56 	end = dec_ioasic_hpt_read();
57 
58 	freq = (end - start) * 10;
59 	printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq);
60 
61 	clocksource_dec.rating = 200 + freq / 10000000;
62 	clocksource_set_clock(&clocksource_dec, freq);
63 
64 	clocksource_register(&clocksource_dec);
65 }
66