Merge git://oss.sgi.com:8090/xfs/xfs-2.6
[linux-2.6] / 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/errno.h>
16 #include <linux/time.h>
17 #include <linux/timex.h>
18 #include <linux/interrupt.h>
19 #include <linux/module.h>
20 #include <linux/init.h>
21 #include <linux/irq.h>
22 #include <linux/profile.h>
23 #include <linux/delay.h>
24
25 #include <asm/timex.h>
26 #include <asm/platform.h>
27
28
29 DEFINE_SPINLOCK(rtc_lock);
30 EXPORT_SYMBOL(rtc_lock);
31
32
33 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
34 unsigned long ccount_per_jiffy;         /* per 1/HZ */
35 unsigned long ccount_nsec;              /* nsec per ccount increment */
36 #endif
37
38 unsigned int last_ccount_stamp;
39 static long last_rtc_update = 0;
40
41 static irqreturn_t timer_interrupt(int irq, void *dev_id);
42 static struct irqaction timer_irqaction = {
43         .handler =      timer_interrupt,
44         .flags =        IRQF_DISABLED,
45         .name =         "timer",
46 };
47
48 void __init time_init(void)
49 {
50         time_t sec_o, sec_n = 0;
51
52         /* The platform must provide a function to calibrate the processor
53          * speed for the CALIBRATE.
54          */
55
56 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
57         printk("Calibrating CPU frequency ");
58         platform_calibrate_ccount();
59         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
60                         (int)(ccount_per_jiffy/(10000/HZ))%100);
61 #endif
62
63         /* Set time from RTC (if provided) */
64
65         if (platform_get_rtc_time(&sec_o) == 0)
66                 while (platform_get_rtc_time(&sec_n))
67                         if (sec_o != sec_n)
68                                 break;
69
70         xtime.tv_nsec = 0;
71         last_rtc_update = xtime.tv_sec = sec_n;
72         last_ccount_stamp = get_ccount();
73
74         set_normalized_timespec(&wall_to_monotonic,
75                 -xtime.tv_sec, -xtime.tv_nsec);
76
77         /* Initialize the linux timer interrupt. */
78
79         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
80         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
81 }
82
83
84 int do_settimeofday(struct timespec *tv)
85 {
86         time_t wtm_sec, sec = tv->tv_sec;
87         long wtm_nsec, nsec = tv->tv_nsec;
88         unsigned long ccount;
89
90         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
91                 return -EINVAL;
92
93         write_seqlock_irq(&xtime_lock);
94
95         /* This is revolting. We need to set "xtime" correctly. However, the
96          * value in this location is the value at the most recent update of
97          * wall time.  Discover what correction gettimeofday() would have
98          * made, and then undo it!
99          */
100         ccount = get_ccount();
101         nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
102
103         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
104         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
105
106         set_normalized_timespec(&xtime, sec, nsec);
107         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
108
109         ntp_clear();
110         write_sequnlock_irq(&xtime_lock);
111         return 0;
112 }
113
114 EXPORT_SYMBOL(do_settimeofday);
115
116
117 void do_gettimeofday(struct timeval *tv)
118 {
119         unsigned long flags;
120         unsigned long sec, usec, delta, seq;
121
122         do {
123                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
124
125                 delta = get_ccount() - last_ccount_stamp;
126                 sec = xtime.tv_sec;
127                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
128         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
129
130         usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
131         for (; usec >= 1000000; sec++, usec -= 1000000)
132                 ;
133
134         tv->tv_sec = sec;
135         tv->tv_usec = usec;
136 }
137
138 EXPORT_SYMBOL(do_gettimeofday);
139
140 /*
141  * The timer interrupt is called HZ times per second.
142  */
143
144 irqreturn_t timer_interrupt (int irq, void *dev_id)
145 {
146
147         unsigned long next;
148
149         next = get_linux_timer();
150
151 again:
152         while ((signed long)(get_ccount() - next) > 0) {
153
154                 profile_tick(CPU_PROFILING);
155 #ifndef CONFIG_SMP
156                 update_process_times(user_mode(get_irq_regs()));
157 #endif
158
159                 write_seqlock(&xtime_lock);
160
161                 last_ccount_stamp = next;
162                 next += CCOUNT_PER_JIFFY;
163                 do_timer (1); /* Linux handler in kernel/timer.c */
164
165                 if (ntp_synced() &&
166                     xtime.tv_sec - last_rtc_update >= 659 &&
167                     abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ) {
168
169                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
170                                 last_rtc_update = xtime.tv_sec+1;
171                         else
172                                 /* Do it again in 60 s */
173                                 last_rtc_update += 60;
174                 }
175                 write_sequnlock(&xtime_lock);
176         }
177
178         /* NOTE: writing CCOMPAREn clears the interrupt.  */
179
180         set_linux_timer (next);
181
182         /* Make sure we didn't miss any tick... */
183
184         if ((signed long)(get_ccount() - next) > 0)
185                 goto again;
186
187         /* Allow platform to do something useful (Wdog). */
188
189         platform_heartbeat();
190
191         return IRQ_HANDLED;
192 }
193
194 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
195 void __devinit calibrate_delay(void)
196 {
197         loops_per_jiffy = CCOUNT_PER_JIFFY;
198         printk("Calibrating delay loop (skipped)... "
199                "%lu.%02lu BogoMIPS preset\n",
200                loops_per_jiffy/(1000000/HZ),
201                (loops_per_jiffy/(10000/HZ)) % 100);
202 }
203 #endif
204