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[linux-2.6.git] / arch / xtensa / kernel / time.c
1 /*
2  * arch/xtensa/kernel/time.c
3  *
4  * Timer and clock support.
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License.  See the file "COPYING" in the main directory of this archive
8  * for more details.
9  *
10  * Copyright (C) 2005 Tensilica Inc.
11  *
12  * Chris Zankel <chris@zankel.net>
13  */
14
15 #include <linux/config.h>
16 #include <linux/errno.h>
17 #include <linux/time.h>
18 #include <linux/timex.h>
19 #include <linux/interrupt.h>
20 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/irq.h>
23 #include <linux/profile.h>
24 #include <linux/delay.h>
25
26 #include <asm/timex.h>
27 #include <asm/platform.h>
28
29
30 extern volatile unsigned long wall_jiffies;
31
32 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
33 EXPORT_SYMBOL(rtc_lock);
34
35
36 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
37 unsigned long ccount_per_jiffy;         /* per 1/HZ */
38 unsigned long ccount_nsec;              /* nsec per ccount increment */
39 #endif
40
41 unsigned int last_ccount_stamp;
42 static long last_rtc_update = 0;
43
44 /*
45  * Scheduler clock - returns current tim in nanosec units.
46  */
47
48 unsigned long long sched_clock(void)
49 {
50         return (unsigned long long)jiffies * (1000000000 / HZ);
51 }
52
53 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
54 static struct irqaction timer_irqaction = {
55         .handler =      timer_interrupt,
56         .flags =        SA_INTERRUPT,
57         .name =         "timer",
58 };
59
60 void __init time_init(void)
61 {
62         time_t sec_o, sec_n = 0;
63
64         /* The platform must provide a function to calibrate the processor
65          * speed for the CALIBRATE.
66          */
67
68 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
69         printk("Calibrating CPU frequency ");
70         platform_calibrate_ccount();
71         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
72                         (int)(ccount_per_jiffy/(10000/HZ))%100);
73 #endif
74
75         /* Set time from RTC (if provided) */
76
77         if (platform_get_rtc_time(&sec_o) == 0)
78                 while (platform_get_rtc_time(&sec_n))
79                         if (sec_o != sec_n)
80                                 break;
81
82         xtime.tv_nsec = 0;
83         last_rtc_update = xtime.tv_sec = sec_n;
84         last_ccount_stamp = get_ccount();
85
86         set_normalized_timespec(&wall_to_monotonic,
87                 -xtime.tv_sec, -xtime.tv_nsec);
88
89         /* Initialize the linux timer interrupt. */
90
91         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
92         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
93 }
94
95
96 int do_settimeofday(struct timespec *tv)
97 {
98         time_t wtm_sec, sec = tv->tv_sec;
99         long wtm_nsec, nsec = tv->tv_nsec;
100         unsigned long ccount;
101
102         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
103                 return -EINVAL;
104
105         write_seqlock_irq(&xtime_lock);
106
107         /* This is revolting. We need to set "xtime" correctly. However, the
108          * value in this location is the value at the most recent update of
109          * wall time.  Discover what correction gettimeofday() would have
110          * made, and then undo it!
111          */
112         ccount = get_ccount();
113         nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
114         nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC;
115
116         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
117         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
118
119         set_normalized_timespec(&xtime, sec, nsec);
120         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
121
122         ntp_clear();
123         write_sequnlock_irq(&xtime_lock);
124         return 0;
125 }
126
127 EXPORT_SYMBOL(do_settimeofday);
128
129
130 void do_gettimeofday(struct timeval *tv)
131 {
132         unsigned long flags;
133         unsigned long sec, usec, delta, lost, seq;
134
135         do {
136                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
137
138                 delta = get_ccount() - last_ccount_stamp;
139                 sec = xtime.tv_sec;
140                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
141
142                 lost = jiffies - wall_jiffies;
143
144         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
145
146         usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
147         for (; usec >= 1000000; sec++, usec -= 1000000)
148                 ;
149
150         tv->tv_sec = sec;
151         tv->tv_usec = usec;
152 }
153
154 EXPORT_SYMBOL(do_gettimeofday);
155
156 /*
157  * The timer interrupt is called HZ times per second.
158  */
159
160 irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
161 {
162
163         unsigned long next;
164
165         next = get_linux_timer();
166
167 again:
168         while ((signed long)(get_ccount() - next) > 0) {
169
170                 profile_tick(CPU_PROFILING, regs);
171 #ifndef CONFIG_SMP
172                 update_process_times(user_mode(regs));
173 #endif
174
175                 write_seqlock(&xtime_lock);
176
177                 last_ccount_stamp = next;
178                 next += CCOUNT_PER_JIFFY;
179                 do_timer (regs); /* Linux handler in kernel/timer.c */
180
181                 if (ntp_synced() &&
182                     xtime.tv_sec - last_rtc_update >= 659 &&
183                     abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ &&
184                     jiffies - wall_jiffies == 1) {
185
186                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
187                                 last_rtc_update = xtime.tv_sec+1;
188                         else
189                                 /* Do it again in 60 s */
190                                 last_rtc_update += 60;
191                 }
192                 write_sequnlock(&xtime_lock);
193         }
194
195         /* NOTE: writing CCOMPAREn clears the interrupt.  */
196
197         set_linux_timer (next);
198
199         /* Make sure we didn't miss any tick... */
200
201         if ((signed long)(get_ccount() - next) > 0)
202                 goto again;
203
204         /* Allow platform to do something useful (Wdog). */
205
206         platform_heartbeat();
207
208         return IRQ_HANDLED;
209 }
210
211 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
212 void __devinit calibrate_delay(void)
213 {
214         loops_per_jiffy = CCOUNT_PER_JIFFY;
215         printk("Calibrating delay loop (skipped)... "
216                "%lu.%02lu BogoMIPS preset\n",
217                loops_per_jiffy/(1000000/HZ),
218                (loops_per_jiffy/(10000/HZ)) % 100);
219 }
220 #endif
221