daa02d45f03ded61e63fe24833b784f42fe8140a
[linux-2.6.git] / arch / blackfin / kernel / time.c
1 /*
2  * arch/blackfin/kernel/time.c
3  *
4  * This file contains the Blackfin-specific time handling details.
5  * Most of the stuff is located in the machine specific files.
6  *
7  * Copyright 2004-2008 Analog Devices Inc.
8  * Licensed under the GPL-2 or later.
9  */
10
11 #include <linux/module.h>
12 #include <linux/profile.h>
13 #include <linux/interrupt.h>
14 #include <linux/time.h>
15 #include <linux/irq.h>
16 #include <linux/delay.h>
17
18 #include <asm/blackfin.h>
19 #include <asm/time.h>
20 #include <asm/gptimers.h>
21
22 /* This is an NTP setting */
23 #define TICK_SIZE (tick_nsec / 1000)
24
25 static struct irqaction bfin_timer_irq = {
26         .name = "Blackfin Timer Tick",
27 #ifdef CONFIG_IRQ_PER_CPU
28         .flags = IRQF_DISABLED | IRQF_PERCPU,
29 #else
30         .flags = IRQF_DISABLED
31 #endif
32 };
33
34 #if defined(CONFIG_TICKSOURCE_GPTMR0) || defined(CONFIG_IPIPE)
35 void __init setup_system_timer0(void)
36 {
37         /* Power down the core timer, just to play safe. */
38         bfin_write_TCNTL(0);
39
40         disable_gptimers(TIMER0bit);
41         set_gptimer_status(0, TIMER_STATUS_TRUN0);
42         while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
43                 udelay(10);
44
45         set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
46         set_gptimer_period(TIMER0_id, get_sclk() / HZ);
47         set_gptimer_pwidth(TIMER0_id, 1);
48         SSYNC();
49         enable_gptimers(TIMER0bit);
50 }
51 #else
52 void __init setup_core_timer(void)
53 {
54         u32 tcount;
55
56         /* power up the timer, but don't enable it just yet */
57         bfin_write_TCNTL(1);
58         CSYNC();
59
60         /* the TSCALE prescaler counter */
61         bfin_write_TSCALE(TIME_SCALE - 1);
62
63         tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
64         bfin_write_TPERIOD(tcount);
65         bfin_write_TCOUNT(tcount);
66
67         /* now enable the timer */
68         CSYNC();
69
70         bfin_write_TCNTL(7);
71 }
72 #endif
73
74 static void __init
75 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
76 {
77 #if defined(CONFIG_TICKSOURCE_GPTMR0) || defined(CONFIG_IPIPE)
78         setup_system_timer0();
79         bfin_timer_irq.handler = timer_routine;
80         setup_irq(IRQ_TIMER0, &bfin_timer_irq);
81 #else
82         setup_core_timer();
83         bfin_timer_irq.handler = timer_routine;
84         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
85 #endif
86 }
87
88 /*
89  * Should return useconds since last timer tick
90  */
91 #ifndef CONFIG_GENERIC_TIME
92 static unsigned long gettimeoffset(void)
93 {
94         unsigned long offset;
95         unsigned long clocks_per_jiffy;
96
97 #if defined(CONFIG_TICKSOURCE_GPTMR0) || defined(CONFIG_IPIPE)
98         clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
99         offset = bfin_read_TIMER0_COUNTER() / \
100                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
101
102         if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
103                 offset += (USEC_PER_SEC / HZ);
104 #else
105         clocks_per_jiffy = bfin_read_TPERIOD();
106         offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
107                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
108
109         /* Check if we just wrapped the counters and maybe missed a tick */
110         if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
111                 && (offset < (100000 / HZ / 2)))
112                 offset += (USEC_PER_SEC / HZ);
113 #endif
114         return offset;
115 }
116 #endif
117
118 static inline int set_rtc_mmss(unsigned long nowtime)
119 {
120         return 0;
121 }
122
123 /*
124  * timer_interrupt() needs to keep up the real-time clock,
125  * as well as call the "do_timer()" routine every clocktick
126  */
127 #ifdef CONFIG_CORE_TIMER_IRQ_L1
128 __attribute__((l1_text))
129 #endif
130 irqreturn_t timer_interrupt(int irq, void *dummy)
131 {
132         /* last time the cmos clock got updated */
133         static long last_rtc_update;
134
135         write_seqlock(&xtime_lock);
136 #if defined(CONFIG_TICKSOURCE_GPTMR0) && !defined(CONFIG_IPIPE)
137         /*
138          * TIMIL0 is latched in __ipipe_grab_irq() when the I-Pipe is
139          * enabled.
140          */
141         if (get_gptimer_status(0) & TIMER_STATUS_TIMIL0) {
142 #endif
143                 do_timer(1);
144
145                 /*
146                  * If we have an externally synchronized Linux clock, then update
147                  * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
148                  * called as close as possible to 500 ms before the new second starts.
149                  */
150                 if (ntp_synced() &&
151                     xtime.tv_sec > last_rtc_update + 660 &&
152                     (xtime.tv_nsec / NSEC_PER_USEC) >=
153                     500000 - ((unsigned)TICK_SIZE) / 2
154                     && (xtime.tv_nsec / NSEC_PER_USEC) <=
155                     500000 + ((unsigned)TICK_SIZE) / 2) {
156                         if (set_rtc_mmss(xtime.tv_sec) == 0)
157                                 last_rtc_update = xtime.tv_sec;
158                         else
159                                 /* Do it again in 60s. */
160                                 last_rtc_update = xtime.tv_sec - 600;
161                 }
162 #if defined(CONFIG_TICKSOURCE_GPTMR0) && !defined(CONFIG_IPIPE)
163                 set_gptimer_status(0, TIMER_STATUS_TIMIL0);
164         }
165 #endif
166         write_sequnlock(&xtime_lock);
167
168 #ifdef CONFIG_IPIPE
169         update_root_process_times(get_irq_regs());
170 #else
171         update_process_times(user_mode(get_irq_regs()));
172 #endif
173         profile_tick(CPU_PROFILING);
174
175         return IRQ_HANDLED;
176 }
177
178 void __init time_init(void)
179 {
180         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
181
182 #ifdef CONFIG_RTC_DRV_BFIN
183         /* [#2663] hack to filter junk RTC values that would cause
184          * userspace to have to deal with time values greater than
185          * 2^31 seconds (which uClibc cannot cope with yet)
186          */
187         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
188                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
189                 bfin_write_RTC_STAT(0);
190         }
191 #endif
192
193         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
194         xtime.tv_sec = secs_since_1970;
195         xtime.tv_nsec = 0;
196
197         wall_to_monotonic.tv_sec = -xtime.tv_sec;
198
199         time_sched_init(timer_interrupt);
200 }
201
202 #ifndef CONFIG_GENERIC_TIME
203 void do_gettimeofday(struct timeval *tv)
204 {
205         unsigned long flags;
206         unsigned long seq;
207         unsigned long usec, sec;
208
209         do {
210                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
211                 usec = gettimeoffset();
212                 sec = xtime.tv_sec;
213                 usec += (xtime.tv_nsec / NSEC_PER_USEC);
214         }
215         while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
216
217         while (usec >= USEC_PER_SEC) {
218                 usec -= USEC_PER_SEC;
219                 sec++;
220         }
221
222         tv->tv_sec = sec;
223         tv->tv_usec = usec;
224 }
225 EXPORT_SYMBOL(do_gettimeofday);
226
227 int do_settimeofday(struct timespec *tv)
228 {
229         time_t wtm_sec, sec = tv->tv_sec;
230         long wtm_nsec, nsec = tv->tv_nsec;
231
232         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
233                 return -EINVAL;
234
235         write_seqlock_irq(&xtime_lock);
236         /*
237          * This is revolting. We need to set the xtime.tv_usec
238          * correctly. However, the value in this location is
239          * is value at the last tick.
240          * Discover what correction gettimeofday
241          * would have done, and then undo it!
242          */
243         nsec -= (gettimeoffset() * NSEC_PER_USEC);
244
245         wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
246         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
247
248         set_normalized_timespec(&xtime, sec, nsec);
249         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
250
251         ntp_clear();
252
253         write_sequnlock_irq(&xtime_lock);
254         clock_was_set();
255
256         return 0;
257 }
258 EXPORT_SYMBOL(do_settimeofday);
259 #endif /* !CONFIG_GENERIC_TIME */
260
261 /*
262  * Scheduler clock - returns current time in nanosec units.
263  */
264 unsigned long long sched_clock(void)
265 {
266         return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
267 }