summaryrefslogtreecommitdiffstats
path: root/arch/arm26/kernel/time.c
blob: 80adbd005fc51812a8a0bc1701e37513c424f5b0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
/*
 *  linux/arch/arm26/kernel/time.c
 *
 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *  Modifications for ARM (C) 1994-2001 Russell King
 *  Mods for ARM26 (C) 2003 Ian Molton
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  This file contains the ARM-specific time handling details:
 *  reading the RTC at bootup, etc...
 *
 *  1994-07-02  Alan Modra
 *              fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
 *  1998-12-20  Updated NTP code according to technical memorandum Jan '96
 *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/profile.h>

#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/ioc.h>

extern unsigned long wall_jiffies;

/* this needs a better home */
DEFINE_SPINLOCK(rtc_lock);

/* change this if you have some constant time drift */
#define USECS_PER_JIFFY	(1000000/HZ)

static int dummy_set_rtc(void)
{
	return 0;
}

/*
 * hook for setting the RTC's idea of the current time.
 */
int (*set_rtc)(void) = dummy_set_rtc;

/*
 * Get time offset based on IOCs timer.
 * FIXME - if this is called with interrutps off, why the shennanigans
 * below ?
 */
static unsigned long gettimeoffset(void)
{
        unsigned int count1, count2, status;
        long offset;

        ioc_writeb (0, IOC_T0LATCH);
        barrier ();
        count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
        barrier ();
        status = ioc_readb(IOC_IRQREQA);
        barrier ();
        ioc_writeb (0, IOC_T0LATCH);
        barrier ();
        count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);

        offset = count2;
        if (count2 < count1) {
                /*
                 * We have not had an interrupt between reading count1
                 * and count2.
                 */
                if (status & (1 << 5))
                        offset -= LATCH;
        } else if (count2 > count1) {
                /*
                 * We have just had another interrupt between reading
                 * count1 and count2.
                 */
                offset -= LATCH;
        }

        offset = (LATCH - offset) * (tick_nsec / 1000);
        return (offset + LATCH/2) / LATCH;
}

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
	return (unsigned long long)jiffies * (1000000000 / HZ);
}

static unsigned long next_rtc_update;

/*
 * If we have an externally synchronized linux clock, then update
 * CMOS clock accordingly every ~11 minutes.  set_rtc() has to be
 * called as close as possible to 500 ms before the new second
 * starts.
 */
static inline void do_set_rtc(void)
{
	if (!ntp_synced() || set_rtc == NULL)
		return;

//FIXME - timespec.tv_sec is a time_t not unsigned long
	if (next_rtc_update &&
	    time_before((unsigned long)xtime.tv_sec, next_rtc_update))
		return;

	if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
	    xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
		return;

	if (set_rtc())
		/*
		 * rtc update failed.  Try again in 60s
		 */
		next_rtc_update = xtime.tv_sec + 60;
	else
		next_rtc_update = xtime.tv_sec + 660;
}

#define do_leds()

void do_gettimeofday(struct timeval *tv)
{
	unsigned long flags;
	unsigned long seq;
	unsigned long usec, sec, lost;

	do {
		seq = read_seqbegin_irqsave(&xtime_lock, flags);
		usec = gettimeoffset();

		lost = jiffies - wall_jiffies;
		if (lost)
			usec += lost * USECS_PER_JIFFY;

		sec = xtime.tv_sec;
		usec += xtime.tv_nsec / 1000;
	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

	/* usec may have gone up a lot: be safe */
	while (usec >= 1000000) {
		usec -= 1000000;
		sec++;
	}

	tv->tv_sec = sec;
	tv->tv_usec = usec;
}

EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
		return -EINVAL;

	write_seqlock_irq(&xtime_lock);
	/*
	 * This is revolting. We need to set "xtime" correctly. However, the
	 * value in this location is the value at the most recent update of
	 * wall time.  Discover what correction gettimeofday() would have
	 * done, and then undo it!
	 */
	tv->tv_nsec -= 1000 * (gettimeoffset() +
			(jiffies - wall_jiffies) * USECS_PER_JIFFY);

	while (tv->tv_nsec < 0) {
		tv->tv_nsec += NSEC_PER_SEC;
		tv->tv_sec--;
	}

	xtime.tv_sec = tv->tv_sec;
	xtime.tv_nsec = tv->tv_nsec;
	ntp_clear();
	write_sequnlock_irq(&xtime_lock);
	clock_was_set();
	return 0;
}

EXPORT_SYMBOL(do_settimeofday);

static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        do_timer(1);
#ifndef CONFIG_SMP
	update_process_times(user_mode(regs));
#endif
        do_set_rtc(); //FIME - EVERY timer IRQ?
        profile_tick(CPU_PROFILING, regs);
	return IRQ_HANDLED; //FIXME - is this right?
}

static struct irqaction timer_irq = {
	.name	= "timer",
	.flags	= IRQF_DISABLED,
	.handler = timer_interrupt,
};

extern void ioctime_init(void);

/*
 * Set up timer interrupt.
 */
void __init time_init(void)
{
	ioc_writeb(LATCH & 255, IOC_T0LTCHL);
        ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
        ioc_writeb(0, IOC_T0GO);


        setup_irq(IRQ_TIMER, &timer_irq);
}