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authorChris Zankel <chris@zankel.net>2007-08-05 13:26:30 -0400
committerChris Zankel <chris@zankel.net>2007-08-27 16:53:37 -0400
commit2b8aea74e78e977b1f9987e23e3e59f3ef4359f4 (patch)
tree920ad1edaf51eccbabae05110101a1d65b8c0580 /arch
parentbc671aa9838f234ccfc794a77325628f1e41e083 (diff)
[XTENSA] Fix timer instabilities.
The timer code could have missed a tick. Signed-off-by: Chris Zankel <chris@zankel.net>
Diffstat (limited to 'arch')
-rw-r--r--arch/xtensa/kernel/time.c46
1 files changed, 29 insertions, 17 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 22949be4a5d8..60d29fe0b1bd 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -32,12 +32,20 @@ EXPORT_SYMBOL(rtc_lock);
32 32
33#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 33#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
34unsigned long ccount_per_jiffy; /* per 1/HZ */ 34unsigned long ccount_per_jiffy; /* per 1/HZ */
35unsigned long ccount_nsec; /* nsec per ccount increment */ 35unsigned long nsec_per_ccount; /* nsec per ccount increment */
36#endif 36#endif
37 37
38unsigned int last_ccount_stamp;
39static long last_rtc_update = 0; 38static long last_rtc_update = 0;
40 39
40/*
41 * Scheduler clock - returns current tim in nanosec units.
42 */
43
44unsigned long long sched_clock(void)
45{
46 return (unsigned long long)jiffies * (1000000000 / HZ);
47}
48
41static irqreturn_t timer_interrupt(int irq, void *dev_id); 49static irqreturn_t timer_interrupt(int irq, void *dev_id);
42static struct irqaction timer_irqaction = { 50static struct irqaction timer_irqaction = {
43 .handler = timer_interrupt, 51 .handler = timer_interrupt,
@@ -69,7 +77,6 @@ void __init time_init(void)
69 77
70 xtime.tv_nsec = 0; 78 xtime.tv_nsec = 0;
71 last_rtc_update = xtime.tv_sec = sec_n; 79 last_rtc_update = xtime.tv_sec = sec_n;
72 last_ccount_stamp = get_ccount();
73 80
74 set_normalized_timespec(&wall_to_monotonic, 81 set_normalized_timespec(&wall_to_monotonic,
75 -xtime.tv_sec, -xtime.tv_nsec); 82 -xtime.tv_sec, -xtime.tv_nsec);
@@ -85,7 +92,7 @@ int do_settimeofday(struct timespec *tv)
85{ 92{
86 time_t wtm_sec, sec = tv->tv_sec; 93 time_t wtm_sec, sec = tv->tv_sec;
87 long wtm_nsec, nsec = tv->tv_nsec; 94 long wtm_nsec, nsec = tv->tv_nsec;
88 unsigned long ccount; 95 unsigned long delta;
89 96
90 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) 97 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
91 return -EINVAL; 98 return -EINVAL;
@@ -97,8 +104,10 @@ int do_settimeofday(struct timespec *tv)
97 * wall time. Discover what correction gettimeofday() would have 104 * wall time. Discover what correction gettimeofday() would have
98 * made, and then undo it! 105 * made, and then undo it!
99 */ 106 */
100 ccount = get_ccount(); 107
101 nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC; 108 delta = CCOUNT_PER_JIFFY;
109 delta += get_ccount() - get_linux_timer();
110 nsec -= delta * NSEC_PER_CCOUNT;
102 111
103 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); 112 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
104 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 113 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
@@ -117,17 +126,21 @@ EXPORT_SYMBOL(do_settimeofday);
117void do_gettimeofday(struct timeval *tv) 126void do_gettimeofday(struct timeval *tv)
118{ 127{
119 unsigned long flags; 128 unsigned long flags;
120 unsigned long sec, usec, delta, seq; 129 unsigned long volatile sec, usec, delta, seq;
121 130
122 do { 131 do {
123 seq = read_seqbegin_irqsave(&xtime_lock, flags); 132 seq = read_seqbegin_irqsave(&xtime_lock, flags);
124 133
125 delta = get_ccount() - last_ccount_stamp;
126 sec = xtime.tv_sec; 134 sec = xtime.tv_sec;
127 usec = (xtime.tv_nsec / NSEC_PER_USEC); 135 usec = (xtime.tv_nsec / NSEC_PER_USEC);
136
137 delta = get_linux_timer() - get_ccount();
138
128 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 139 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
129 140
130 usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC; 141 usec += (((unsigned long) CCOUNT_PER_JIFFY - delta)
142 * (unsigned long) NSEC_PER_CCOUNT) / NSEC_PER_USEC;
143
131 for (; usec >= 1000000; sec++, usec -= 1000000) 144 for (; usec >= 1000000; sec++, usec -= 1000000)
132 ; 145 ;
133 146
@@ -158,9 +171,12 @@ again:
158 171
159 write_seqlock(&xtime_lock); 172 write_seqlock(&xtime_lock);
160 173
161 last_ccount_stamp = next; 174 do_timer(1); /* Linux handler in kernel/timer.c */
175
176 /* Note that writing CCOMPARE clears the interrupt. */
177
162 next += CCOUNT_PER_JIFFY; 178 next += CCOUNT_PER_JIFFY;
163 do_timer (1); /* Linux handler in kernel/timer.c */ 179 set_linux_timer(next);
164 180
165 if (ntp_synced() && 181 if (ntp_synced() &&
166 xtime.tv_sec - last_rtc_update >= 659 && 182 xtime.tv_sec - last_rtc_update >= 659 &&
@@ -175,19 +191,15 @@ again:
175 write_sequnlock(&xtime_lock); 191 write_sequnlock(&xtime_lock);
176 } 192 }
177 193
178 /* NOTE: writing CCOMPAREn clears the interrupt. */ 194 /* Allow platform to do something useful (Wdog). */
179 195
180 set_linux_timer (next); 196 platform_heartbeat();
181 197
182 /* Make sure we didn't miss any tick... */ 198 /* Make sure we didn't miss any tick... */
183 199
184 if ((signed long)(get_ccount() - next) > 0) 200 if ((signed long)(get_ccount() - next) > 0)
185 goto again; 201 goto again;
186 202
187 /* Allow platform to do something useful (Wdog). */
188
189 platform_heartbeat();
190
191 return IRQ_HANDLED; 203 return IRQ_HANDLED;
192} 204}
193 205