2 * arch/xtensa/kernel/time.c
4 * Timer and clock support.
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
10 * Copyright (C) 2005 Tensilica Inc.
12 * Chris Zankel <chris@zankel.net>
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>
25 #include <asm/timex.h>
26 #include <asm/platform.h>
29 DEFINE_SPINLOCK(rtc_lock
);
30 EXPORT_SYMBOL(rtc_lock
);
33 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
34 unsigned long ccount_per_jiffy
; /* per 1/HZ */
35 unsigned long ccount_nsec
; /* nsec per ccount increment */
38 unsigned int last_ccount_stamp
;
39 static long last_rtc_update
= 0;
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
,
48 void __init
time_init(void)
50 time_t sec_o
, sec_n
= 0;
52 /* The platform must provide a function to calibrate the processor
53 * speed for the CALIBRATE.
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);
63 /* Set time from RTC (if provided) */
65 if (platform_get_rtc_time(&sec_o
) == 0)
66 while (platform_get_rtc_time(&sec_n
))
71 last_rtc_update
= xtime
.tv_sec
= sec_n
;
72 last_ccount_stamp
= get_ccount();
74 set_normalized_timespec(&wall_to_monotonic
,
75 -xtime
.tv_sec
, -xtime
.tv_nsec
);
77 /* Initialize the linux timer interrupt. */
79 setup_irq(LINUX_TIMER_INT
, &timer_irqaction
);
80 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY
);
84 int do_settimeofday(struct timespec
*tv
)
86 time_t wtm_sec
, sec
= tv
->tv_sec
;
87 long wtm_nsec
, nsec
= tv
->tv_nsec
;
90 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
93 write_seqlock_irq(&xtime_lock
);
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!
100 ccount
= get_ccount();
101 nsec
-= (ccount
- last_ccount_stamp
) * CCOUNT_NSEC
;
103 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- sec
);
104 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- nsec
);
106 set_normalized_timespec(&xtime
, sec
, nsec
);
107 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
110 write_sequnlock_irq(&xtime_lock
);
114 EXPORT_SYMBOL(do_settimeofday
);
117 void do_gettimeofday(struct timeval
*tv
)
120 unsigned long sec
, usec
, delta
, seq
;
123 seq
= read_seqbegin_irqsave(&xtime_lock
, flags
);
125 delta
= get_ccount() - last_ccount_stamp
;
127 usec
= (xtime
.tv_nsec
/ NSEC_PER_USEC
);
128 } while (read_seqretry_irqrestore(&xtime_lock
, seq
, flags
));
130 usec
+= (delta
* CCOUNT_NSEC
) / NSEC_PER_USEC
;
131 for (; usec
>= 1000000; sec
++, usec
-= 1000000)
138 EXPORT_SYMBOL(do_gettimeofday
);
141 * The timer interrupt is called HZ times per second.
144 irqreturn_t
timer_interrupt (int irq
, void *dev_id
)
149 next
= get_linux_timer();
152 while ((signed long)(get_ccount() - next
) > 0) {
154 profile_tick(CPU_PROFILING
);
156 update_process_times(user_mode(get_irq_regs()));
159 write_seqlock(&xtime_lock
);
161 last_ccount_stamp
= next
;
162 next
+= CCOUNT_PER_JIFFY
;
163 do_timer (1); /* Linux handler in kernel/timer.c */
166 xtime
.tv_sec
- last_rtc_update
>= 659 &&
167 abs((xtime
.tv_nsec
/1000)-(1000000-1000000/HZ
))<5000000/HZ
) {
169 if (platform_set_rtc_time(xtime
.tv_sec
+1) == 0)
170 last_rtc_update
= xtime
.tv_sec
+1;
172 /* Do it again in 60 s */
173 last_rtc_update
+= 60;
175 write_sequnlock(&xtime_lock
);
178 /* NOTE: writing CCOMPAREn clears the interrupt. */
180 set_linux_timer (next
);
182 /* Make sure we didn't miss any tick... */
184 if ((signed long)(get_ccount() - next
) > 0)
187 /* Allow platform to do something useful (Wdog). */
189 platform_heartbeat();
194 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
195 void __devinit
calibrate_delay(void)
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);