1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  DEC I/O ASIC's counter clocksource
4 *
5 *  Copyright (C) 2008	Yoichi Yuasa <yuasa@linux-mips.org>
6 */
7#include <linux/clocksource.h>
8#include <linux/sched_clock.h>
9#include <linux/init.h>
10
11#include <asm/ds1287.h>
12#include <asm/time.h>
13#include <asm/dec/ioasic.h>
14#include <asm/dec/ioasic_addrs.h>
15
16static u64 dec_ioasic_hpt_read(struct clocksource *cs)
17{
18	return ioasic_read(IO_REG_FCTR);
19}
20
21static struct clocksource clocksource_dec = {
22	.name		= "dec-ioasic",
23	.read		= dec_ioasic_hpt_read,
24	.mask		= CLOCKSOURCE_MASK(32),
25	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
26};
27
28static u64 notrace dec_ioasic_read_sched_clock(void)
29{
30	return ioasic_read(IO_REG_FCTR);
31}
32
33int __init dec_ioasic_clocksource_init(void)
34{
35	unsigned int freq;
36	u32 start, end;
37	int i = HZ / 8;
38
39	ds1287_timer_state();
40	while (!ds1287_timer_state())
41		;
42
43	start = dec_ioasic_hpt_read(&clocksource_dec);
44
45	while (i--)
46		while (!ds1287_timer_state())
47			;
48
49	end = dec_ioasic_hpt_read(&clocksource_dec);
50
51	freq = (end - start) * 8;
52
53	/* An early revision of the I/O ASIC didn't have the counter.  */
54	if (!freq)
55		return -ENXIO;
56
57	printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq);
58
59	clocksource_dec.rating = 200 + freq / 10000000;
60	clocksource_register_hz(&clocksource_dec, freq);
61
62	sched_clock_register(dec_ioasic_read_sched_clock, 32, freq);
63
64	return 0;
65}
66