summaryrefslogtreecommitdiff
path: root/arch/parisc/kernel/time.c
blob: 594930bc4bcf6d3df7231e0545bdbfbf5bb3842b (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
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*
 *  linux/arch/parisc/kernel/time.c
 *
 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *  Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
 *  Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
 *
 * 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/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/profile.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/param.h>
#include <asm/pdc.h>
#include <asm/led.h>

#include <linux/timex.h>

/* xtime and wall_jiffies keep wall-clock time */
extern unsigned long wall_jiffies;

static long clocktick __read_mostly;	/* timer cycles per tick */
static long halftick __read_mostly;

#ifdef CONFIG_SMP
extern void smp_do_timer(struct pt_regs *regs);
#endif

irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	long now;
	long next_tick;
	int nticks;
	int cpu = smp_processor_id();

	profile_tick(CPU_PROFILING, regs);

	now = mfctl(16);
	/* initialize next_tick to time at last clocktick */
	next_tick = cpu_data[cpu].it_value;

	/* since time passes between the interrupt and the mfctl()
	 * above, it is never true that last_tick + clocktick == now.  If we
	 * never miss a clocktick, we could set next_tick = last_tick + clocktick
	 * but maybe we'll miss ticks, hence the loop.
	 *
	 * Variables are *signed*.
	 */

	nticks = 0;
	while((next_tick - now) < halftick) {
		next_tick += clocktick;
		nticks++;
	}
	mtctl(next_tick, 16);
	cpu_data[cpu].it_value = next_tick;

	while (nticks--) {
#ifdef CONFIG_SMP
		smp_do_timer(regs);
#else
		update_process_times(user_mode(regs));
#endif
		if (cpu == 0) {
			write_seqlock(&xtime_lock);
			do_timer(regs);
			write_sequnlock(&xtime_lock);
		}
	}
    
	/* check soft power switch status */
	if (cpu == 0 && !atomic_read(&power_tasklet.count))
		tasklet_schedule(&power_tasklet);

	return IRQ_HANDLED;
}


unsigned long profile_pc(struct pt_regs *regs)
{
	unsigned long pc = instruction_pointer(regs);

	if (regs->gr[0] & PSW_N)
		pc -= 4;

#ifdef CONFIG_SMP
	if (in_lock_functions(pc))
		pc = regs->gr[2];
#endif

	return pc;
}
EXPORT_SYMBOL(profile_pc);


/*** converted from ia64 ***/
/*
 * Return the number of micro-seconds that elapsed since the last
 * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock
 * must be at least read-locked when calling this routine.
 */
static inline unsigned long
gettimeoffset (void)
{
#ifndef CONFIG_SMP
	/*
	 * FIXME: This won't work on smp because jiffies are updated by cpu 0.
	 *    Once parisc-linux learns the cr16 difference between processors,
	 *    this could be made to work.
	 */
	long last_tick;
	long elapsed_cycles;

	/* it_value is the intended time of the next tick */
	last_tick = cpu_data[smp_processor_id()].it_value;

	/* Subtract one tick and account for possible difference between
	 * when we expected the tick and when it actually arrived.
	 * (aka wall vs real)
	 */
	last_tick -= clocktick * (jiffies - wall_jiffies + 1);
	elapsed_cycles = mfctl(16) - last_tick;

	/* the precision of this math could be improved */
	return elapsed_cycles / (PAGE0->mem_10msec / 10000);
#else
	return 0;
#endif
}

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

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

	while (usec >= 1000000) {
		usec -= 1000000;
		++sec;
	}

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

EXPORT_SYMBOL(do_gettimeofday);

int
do_settimeofday (struct timespec *tv)
{
	time_t wtm_sec, sec = tv->tv_sec;
	long wtm_nsec, nsec = tv->tv_nsec;

	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!
		 */
		nsec -= gettimeoffset() * 1000;

		wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
		wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);

		set_normalized_timespec(&xtime, sec, nsec);
		set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);

		ntp_clear();
	}
	write_sequnlock_irq(&xtime_lock);
	clock_was_set();
	return 0;
}
EXPORT_SYMBOL(do_settimeofday);

/*
 * XXX: We can do better than this.
 * Returns nanoseconds
 */

unsigned long long sched_clock(void)
{
	return (unsigned long long)jiffies * (1000000000 / HZ);
}


void __init time_init(void)
{
	unsigned long next_tick;
	static struct pdc_tod tod_data;

	clocktick = (100 * PAGE0->mem_10msec) / HZ;
	halftick = clocktick / 2;

	/* Setup clock interrupt timing */

	next_tick = mfctl(16);
	next_tick += clocktick;
	cpu_data[smp_processor_id()].it_value = next_tick;

	/* kick off Itimer (CR16) */
	mtctl(next_tick, 16);

	if(pdc_tod_read(&tod_data) == 0) {
		write_seqlock_irq(&xtime_lock);
		xtime.tv_sec = tod_data.tod_sec;
		xtime.tv_nsec = tod_data.tod_usec * 1000;
		set_normalized_timespec(&wall_to_monotonic,
		                        -xtime.tv_sec, -xtime.tv_nsec);
		write_sequnlock_irq(&xtime_lock);
	} else {
		printk(KERN_ERR "Error reading tod clock\n");
	        xtime.tv_sec = 0;
		xtime.tv_nsec = 0;
	}
}