Merge branch 'header-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[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/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 nsec_per_ccount;          /* nsec per ccount increment */
36 #endif
37
38 static long last_rtc_update = 0;
39
40 /*
41  * Scheduler clock - returns current tim in nanosec units.
42  */
43
44 unsigned long long sched_clock(void)
45 {
46         return (unsigned long long)jiffies * (1000000000 / HZ);
47 }
48
49 static irqreturn_t timer_interrupt(int irq, void *dev_id);
50 static struct irqaction timer_irqaction = {
51         .handler =      timer_interrupt,
52         .flags =        IRQF_DISABLED,
53         .name =         "timer",
54 };
55
56 void __init time_init(void)
57 {
58         time_t sec_o, sec_n = 0;
59
60         /* The platform must provide a function to calibrate the processor
61          * speed for the CALIBRATE.
62          */
63
64 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
65         printk("Calibrating CPU frequency ");
66         platform_calibrate_ccount();
67         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
68                         (int)(ccount_per_jiffy/(10000/HZ))%100);
69 #endif
70
71         /* Set time from RTC (if provided) */
72
73         if (platform_get_rtc_time(&sec_o) == 0)
74                 while (platform_get_rtc_time(&sec_n))
75                         if (sec_o != sec_n)
76                                 break;
77
78         xtime.tv_nsec = 0;
79         last_rtc_update = xtime.tv_sec = sec_n;
80
81         set_normalized_timespec(&wall_to_monotonic,
82                 -xtime.tv_sec, -xtime.tv_nsec);
83
84         /* Initialize the linux timer interrupt. */
85
86         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
87         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
88 }
89
90
91 int do_settimeofday(struct timespec *tv)
92 {
93         time_t wtm_sec, sec = tv->tv_sec;
94         long wtm_nsec, nsec = tv->tv_nsec;
95         unsigned long delta;
96
97         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
98                 return -EINVAL;
99
100         write_seqlock_irq(&xtime_lock);
101
102         /* This is revolting. We need to set "xtime" correctly. However, the
103          * value in this location is the value at the most recent update of
104          * wall time.  Discover what correction gettimeofday() would have
105          * made, and then undo it!
106          */
107
108         delta = CCOUNT_PER_JIFFY;
109         delta += get_ccount() - get_linux_timer();
110         nsec -= delta * NSEC_PER_CCOUNT;
111
112         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
113         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
114
115         set_normalized_timespec(&xtime, sec, nsec);
116         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
117
118         ntp_clear();
119         write_sequnlock_irq(&xtime_lock);
120         return 0;
121 }
122
123 EXPORT_SYMBOL(do_settimeofday);
124
125
126 void do_gettimeofday(struct timeval *tv)
127 {
128         unsigned long flags;
129         unsigned long volatile sec, usec, delta, seq;
130
131         do {
132                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
133
134                 sec = xtime.tv_sec;
135                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
136
137                 delta = get_linux_timer() - get_ccount();
138
139         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
140
141         usec += (((unsigned long) CCOUNT_PER_JIFFY - delta)
142                  * (unsigned long) NSEC_PER_CCOUNT) / NSEC_PER_USEC;
143
144         for (; usec >= 1000000; sec++, usec -= 1000000)
145                 ;
146
147         tv->tv_sec = sec;
148         tv->tv_usec = usec;
149 }
150
151 EXPORT_SYMBOL(do_gettimeofday);
152
153 /*
154  * The timer interrupt is called HZ times per second.
155  */
156
157 irqreturn_t timer_interrupt (int irq, void *dev_id)
158 {
159
160         unsigned long next;
161
162         next = get_linux_timer();
163
164 again:
165         while ((signed long)(get_ccount() - next) > 0) {
166
167                 profile_tick(CPU_PROFILING);
168 #ifndef CONFIG_SMP
169                 update_process_times(user_mode(get_irq_regs()));
170 #endif
171
172                 write_seqlock(&xtime_lock);
173
174                 do_timer(1); /* Linux handler in kernel/timer.c */
175
176                 /* Note that writing CCOMPARE clears the interrupt. */
177
178                 next += CCOUNT_PER_JIFFY;
179                 set_linux_timer(next);
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
185                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
186                                 last_rtc_update = xtime.tv_sec+1;
187                         else
188                                 /* Do it again in 60 s */
189                                 last_rtc_update += 60;
190                 }
191                 write_sequnlock(&xtime_lock);
192         }
193
194         /* Allow platform to do something useful (Wdog). */
195
196         platform_heartbeat();
197
198         /* Make sure we didn't miss any tick... */
199
200         if ((signed long)(get_ccount() - next) > 0)
201                 goto again;
202
203         return IRQ_HANDLED;
204 }
205
206 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
207 void __cpuinit calibrate_delay(void)
208 {
209         loops_per_jiffy = CCOUNT_PER_JIFFY;
210         printk("Calibrating delay loop (skipped)... "
211                "%lu.%02lu BogoMIPS preset\n",
212                loops_per_jiffy/(1000000/HZ),
213                (loops_per_jiffy/(10000/HZ)) % 100);
214 }
215 #endif
216