[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 3
[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 u64 jiffies_64 = INITIAL_JIFFIES;
33 EXPORT_SYMBOL(jiffies_64);
34
35 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
36 EXPORT_SYMBOL(rtc_lock);
37
38
39 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
40 unsigned long ccount_per_jiffy;         /* per 1/HZ */
41 unsigned long ccount_nsec;              /* nsec per ccount increment */
42 #endif
43
44 unsigned int last_ccount_stamp;
45 static long last_rtc_update = 0;
46
47 /*
48  * Scheduler clock - returns current tim in nanosec units.
49  */
50
51 unsigned long long sched_clock(void)
52 {
53         return (unsigned long long)jiffies * (1000000000 / HZ);
54 }
55
56 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
57 static struct irqaction timer_irqaction = {
58         .handler =      timer_interrupt,
59         .flags =        SA_INTERRUPT,
60         .name =         "timer",
61 };
62
63 void __init time_init(void)
64 {
65         time_t sec_o, sec_n = 0;
66
67         /* The platform must provide a function to calibrate the processor
68          * speed for the CALIBRATE.
69          */
70
71 #if CONFIG_XTENSA_CALIBRATE_CCOUNT
72         printk("Calibrating CPU frequency ");
73         platform_calibrate_ccount();
74         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
75                         (int)(ccount_per_jiffy/(10000/HZ))%100);
76 #endif
77
78         /* Set time from RTC (if provided) */
79
80         if (platform_get_rtc_time(&sec_o) == 0)
81                 while (platform_get_rtc_time(&sec_n))
82                         if (sec_o != sec_n)
83                                 break;
84
85         xtime.tv_nsec = 0;
86         last_rtc_update = xtime.tv_sec = sec_n;
87         last_ccount_stamp = get_ccount();
88
89         set_normalized_timespec(&wall_to_monotonic,
90                 -xtime.tv_sec, -xtime.tv_nsec);
91
92         /* Initialize the linux timer interrupt. */
93
94         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
95         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
96 }
97
98
99 int do_settimeofday(struct timespec *tv)
100 {
101         time_t wtm_sec, sec = tv->tv_sec;
102         long wtm_nsec, nsec = tv->tv_nsec;
103         unsigned long ccount;
104
105         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
106                 return -EINVAL;
107
108         write_seqlock_irq(&xtime_lock);
109
110         /* This is revolting. We need to set "xtime" correctly. However, the
111          * value in this location is the value at the most recent update of
112          * wall time.  Discover what correction gettimeofday() would have
113          * made, and then undo it!
114          */
115         ccount = get_ccount();
116         nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
117         nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC;
118
119         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
120         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
121
122         set_normalized_timespec(&xtime, sec, nsec);
123         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
124
125         time_adjust = 0;                /* stop active adjtime() */
126         time_status |= STA_UNSYNC;
127         time_maxerror = NTP_PHASE_LIMIT;
128         time_esterror = NTP_PHASE_LIMIT;
129         write_sequnlock_irq(&xtime_lock);
130         return 0;
131 }
132
133 EXPORT_SYMBOL(do_settimeofday);
134
135
136 void do_gettimeofday(struct timeval *tv)
137 {
138         unsigned long flags;
139         unsigned long sec, usec, delta, lost, seq;
140
141         do {
142                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
143
144                 delta = get_ccount() - last_ccount_stamp;
145                 sec = xtime.tv_sec;
146                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
147
148                 lost = jiffies - wall_jiffies;
149
150         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
151
152         usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
153         for (; usec >= 1000000; sec++, usec -= 1000000)
154                 ;
155
156         tv->tv_sec = sec;
157         tv->tv_usec = usec;
158 }
159
160 EXPORT_SYMBOL(do_gettimeofday);
161
162 /*
163  * The timer interrupt is called HZ times per second.
164  */
165
166 irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
167 {
168
169         unsigned long next;
170
171         next = get_linux_timer();
172
173 again:
174         while ((signed long)(get_ccount() - next) > 0) {
175
176                 profile_tick(CPU_PROFILING, regs);
177 #ifndef CONFIG_SMP
178                 update_process_times(user_mode(regs));
179 #endif
180
181                 write_seqlock(&xtime_lock);
182
183                 last_ccount_stamp = next;
184                 next += CCOUNT_PER_JIFFY;
185                 do_timer (regs); /* Linux handler in kernel/timer.c */
186
187                 if ((time_status & STA_UNSYNC) == 0 &&
188                     xtime.tv_sec - last_rtc_update >= 659 &&
189                     abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ &&
190                     jiffies - wall_jiffies == 1) {
191
192                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
193                                 last_rtc_update = xtime.tv_sec+1;
194                         else
195                                 /* Do it again in 60 s */
196                                 last_rtc_update += 60;
197                 }
198                 write_sequnlock(&xtime_lock);
199         }
200
201         /* NOTE: writing CCOMPAREn clears the interrupt.  */
202
203         set_linux_timer (next);
204
205         /* Make sure we didn't miss any tick... */
206
207         if ((signed long)(get_ccount() - next) > 0)
208                 goto again;
209
210         /* Allow platform to do something usefull (Wdog). */
211
212         platform_heartbeat();
213
214         return IRQ_HANDLED;
215 }
216
217 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
218 void __devinit calibrate_delay(void)
219 {
220         loops_per_jiffy = CCOUNT_PER_JIFFY;
221         printk("Calibrating delay loop (skipped)... "
222                "%lu.%02lu BogoMIPS preset\n",
223                loops_per_jiffy/(1000000/HZ),
224                (loops_per_jiffy/(10000/HZ)) % 100);
225 }
226 #endif
227