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1da177e4 LT |
1 | /* |
2 | * linux/arch/parisc/kernel/time.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds | |
5 | * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King | |
6 | * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org) | |
7 | * | |
8 | * 1994-07-02 Alan Modra | |
9 | * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime | |
10 | * 1998-12-20 Updated NTP code according to technical memorandum Jan '96 | |
11 | * "A Kernel Model for Precision Timekeeping" by Dave Mills | |
12 | */ | |
1da177e4 LT |
13 | #include <linux/errno.h> |
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/param.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/interrupt.h> | |
21 | #include <linux/time.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/smp.h> | |
24 | #include <linux/profile.h> | |
25 | ||
26 | #include <asm/uaccess.h> | |
27 | #include <asm/io.h> | |
28 | #include <asm/irq.h> | |
29 | #include <asm/param.h> | |
30 | #include <asm/pdc.h> | |
31 | #include <asm/led.h> | |
32 | ||
33 | #include <linux/timex.h> | |
34 | ||
bed583f7 | 35 | static unsigned long clocktick __read_mostly; /* timer cycles per tick */ |
1da177e4 LT |
36 | |
37 | #ifdef CONFIG_SMP | |
38 | extern void smp_do_timer(struct pt_regs *regs); | |
39 | #endif | |
40 | ||
1604f318 MW |
41 | /* |
42 | * We keep time on PA-RISC Linux by using the Interval Timer which is | |
43 | * a pair of registers; one is read-only and one is write-only; both | |
44 | * accessed through CR16. The read-only register is 32 or 64 bits wide, | |
45 | * and increments by 1 every CPU clock tick. The architecture only | |
46 | * guarantees us a rate between 0.5 and 2, but all implementations use a | |
47 | * rate of 1. The write-only register is 32-bits wide. When the lowest | |
48 | * 32 bits of the read-only register compare equal to the write-only | |
49 | * register, it raises a maskable external interrupt. Each processor has | |
50 | * an Interval Timer of its own and they are not synchronised. | |
51 | * | |
52 | * We want to generate an interrupt every 1/HZ seconds. So we program | |
53 | * CR16 to interrupt every @clocktick cycles. The it_value in cpu_data | |
54 | * is programmed with the intended time of the next tick. We can be | |
55 | * held off for an arbitrarily long period of time by interrupts being | |
56 | * disabled, so we may miss one or more ticks. | |
57 | */ | |
1da177e4 LT |
58 | irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) |
59 | { | |
bed583f7 GG |
60 | unsigned long now; |
61 | unsigned long next_tick; | |
1604f318 | 62 | unsigned long cycles_elapsed, ticks_elapsed; |
6e5dc42b GG |
63 | unsigned long cycles_remainder; |
64 | unsigned int cpu = smp_processor_id(); | |
1da177e4 | 65 | |
6b799d92 | 66 | /* gcc can optimize for "read-only" case with a local clocktick */ |
6e5dc42b | 67 | unsigned long cpt = clocktick; |
6b799d92 | 68 | |
be577a52 | 69 | profile_tick(CPU_PROFILING); |
1da177e4 | 70 | |
bed583f7 | 71 | /* Initialize next_tick to the expected tick time. */ |
1da177e4 LT |
72 | next_tick = cpu_data[cpu].it_value; |
73 | ||
bed583f7 GG |
74 | /* Get current interval timer. |
75 | * CR16 reads as 64 bits in CPU wide mode. | |
76 | * CR16 reads as 32 bits in CPU narrow mode. | |
1da177e4 | 77 | */ |
bed583f7 | 78 | now = mfctl(16); |
1da177e4 | 79 | |
bed583f7 GG |
80 | cycles_elapsed = now - next_tick; |
81 | ||
6e5dc42b GG |
82 | if ((cycles_elapsed >> 5) < cpt) { |
83 | /* use "cheap" math (add/subtract) instead | |
84 | * of the more expensive div/mul method | |
bed583f7 | 85 | */ |
6b799d92 | 86 | cycles_remainder = cycles_elapsed; |
1604f318 | 87 | ticks_elapsed = 1; |
6e5dc42b GG |
88 | while (cycles_remainder > cpt) { |
89 | cycles_remainder -= cpt; | |
1604f318 | 90 | ticks_elapsed++; |
6e5dc42b | 91 | } |
6b799d92 | 92 | } else { |
6e5dc42b | 93 | cycles_remainder = cycles_elapsed % cpt; |
1604f318 | 94 | ticks_elapsed = 1 + cycles_elapsed / cpt; |
6b799d92 | 95 | } |
bed583f7 GG |
96 | |
97 | /* Can we differentiate between "early CR16" (aka Scenario 1) and | |
98 | * "long delay" (aka Scenario 3)? I don't think so. | |
99 | * | |
100 | * We expected timer_interrupt to be delivered at least a few hundred | |
101 | * cycles after the IT fires. But it's arbitrary how much time passes | |
102 | * before we call it "late". I've picked one second. | |
103 | */ | |
1604f318 | 104 | if (ticks_elapsed > HZ) { |
bed583f7 | 105 | /* Scenario 3: very long delay? bad in any case */ |
6b799d92 | 106 | printk (KERN_CRIT "timer_interrupt(CPU %d): delayed!" |
6e5dc42b | 107 | " cycles %lX rem %lX " |
bed583f7 GG |
108 | " next/now %lX/%lX\n", |
109 | cpu, | |
6e5dc42b | 110 | cycles_elapsed, cycles_remainder, |
bed583f7 | 111 | next_tick, now ); |
bed583f7 GG |
112 | } |
113 | ||
6e5dc42b GG |
114 | /* convert from "division remainder" to "remainder of clock tick" */ |
115 | cycles_remainder = cpt - cycles_remainder; | |
bed583f7 GG |
116 | |
117 | /* Determine when (in CR16 cycles) next IT interrupt will fire. | |
118 | * We want IT to fire modulo clocktick even if we miss/skip some. | |
119 | * But those interrupts don't in fact get delivered that regularly. | |
120 | */ | |
6e5dc42b GG |
121 | next_tick = now + cycles_remainder; |
122 | ||
123 | cpu_data[cpu].it_value = next_tick; | |
6b799d92 GG |
124 | |
125 | /* Skip one clocktick on purpose if we are likely to miss next_tick. | |
6e5dc42b GG |
126 | * We want to avoid the new next_tick being less than CR16. |
127 | * If that happened, itimer wouldn't fire until CR16 wrapped. | |
128 | * We'll catch the tick we missed on the tick after that. | |
129 | */ | |
130 | if (!(cycles_remainder >> 13)) | |
131 | next_tick += cpt; | |
bed583f7 GG |
132 | |
133 | /* Program the IT when to deliver the next interrupt. */ | |
134 | /* Only bottom 32-bits of next_tick are written to cr16. */ | |
6b799d92 | 135 | mtctl(next_tick, 16); |
1da177e4 | 136 | |
6e5dc42b GG |
137 | |
138 | /* Done mucking with unreliable delivery of interrupts. | |
139 | * Go do system house keeping. | |
bed583f7 | 140 | */ |
1da177e4 | 141 | #ifdef CONFIG_SMP |
6e5dc42b | 142 | smp_do_timer(regs); |
1da177e4 | 143 | #else |
6e5dc42b | 144 | update_process_times(user_mode(regs)); |
1da177e4 | 145 | #endif |
6e5dc42b GG |
146 | if (cpu == 0) { |
147 | write_seqlock(&xtime_lock); | |
1604f318 | 148 | do_timer(ticks_elapsed); |
6e5dc42b | 149 | write_sequnlock(&xtime_lock); |
1da177e4 | 150 | } |
6e5dc42b | 151 | |
1da177e4 LT |
152 | /* check soft power switch status */ |
153 | if (cpu == 0 && !atomic_read(&power_tasklet.count)) | |
154 | tasklet_schedule(&power_tasklet); | |
155 | ||
156 | return IRQ_HANDLED; | |
157 | } | |
158 | ||
5cd55b0e RC |
159 | |
160 | unsigned long profile_pc(struct pt_regs *regs) | |
161 | { | |
162 | unsigned long pc = instruction_pointer(regs); | |
163 | ||
164 | if (regs->gr[0] & PSW_N) | |
165 | pc -= 4; | |
166 | ||
167 | #ifdef CONFIG_SMP | |
168 | if (in_lock_functions(pc)) | |
169 | pc = regs->gr[2]; | |
170 | #endif | |
171 | ||
172 | return pc; | |
173 | } | |
174 | EXPORT_SYMBOL(profile_pc); | |
175 | ||
176 | ||
1da177e4 LT |
177 | /* |
178 | * Return the number of micro-seconds that elapsed since the last | |
8ef38609 | 179 | * update to wall time (aka xtime). The xtime_lock |
1da177e4 LT |
180 | * must be at least read-locked when calling this routine. |
181 | */ | |
6e5dc42b | 182 | static inline unsigned long gettimeoffset (void) |
1da177e4 LT |
183 | { |
184 | #ifndef CONFIG_SMP | |
185 | /* | |
186 | * FIXME: This won't work on smp because jiffies are updated by cpu 0. | |
187 | * Once parisc-linux learns the cr16 difference between processors, | |
188 | * this could be made to work. | |
189 | */ | |
bed583f7 GG |
190 | unsigned long now; |
191 | unsigned long prev_tick; | |
192 | unsigned long next_tick; | |
193 | unsigned long elapsed_cycles; | |
194 | unsigned long usec; | |
6b799d92 | 195 | unsigned long cpuid = smp_processor_id(); |
6e5dc42b | 196 | unsigned long cpt = clocktick; |
1da177e4 | 197 | |
6b799d92 | 198 | next_tick = cpu_data[cpuid].it_value; |
bed583f7 | 199 | now = mfctl(16); /* Read the hardware interval timer. */ |
1da177e4 | 200 | |
6e5dc42b | 201 | prev_tick = next_tick - cpt; |
bed583f7 GG |
202 | |
203 | /* Assume Scenario 1: "now" is later than prev_tick. */ | |
204 | elapsed_cycles = now - prev_tick; | |
205 | ||
6e5dc42b GG |
206 | /* aproximate HZ with shifts. Intended math is "(elapsed/clocktick) > HZ" */ |
207 | #if HZ == 1000 | |
208 | if (elapsed_cycles > (cpt << 10) ) | |
209 | #elif HZ == 250 | |
210 | if (elapsed_cycles > (cpt << 8) ) | |
211 | #elif HZ == 100 | |
212 | if (elapsed_cycles > (cpt << 7) ) | |
213 | #else | |
214 | #warn WTF is HZ set to anyway? | |
215 | if (elapsed_cycles > (HZ * cpt) ) | |
216 | #endif | |
217 | { | |
bed583f7 | 218 | /* Scenario 3: clock ticks are missing. */ |
6e5dc42b GG |
219 | printk (KERN_CRIT "gettimeoffset(CPU %ld): missing %ld ticks!" |
220 | " cycles %lX prev/now/next %lX/%lX/%lX clock %lX\n", | |
221 | cpuid, elapsed_cycles / cpt, | |
222 | elapsed_cycles, prev_tick, now, next_tick, cpt); | |
bed583f7 GG |
223 | } |
224 | ||
225 | /* FIXME: Can we improve the precision? Not with PAGE0. */ | |
226 | usec = (elapsed_cycles * 10000) / PAGE0->mem_10msec; | |
bed583f7 | 227 | return usec; |
1da177e4 LT |
228 | #else |
229 | return 0; | |
230 | #endif | |
231 | } | |
232 | ||
233 | void | |
234 | do_gettimeofday (struct timeval *tv) | |
235 | { | |
236 | unsigned long flags, seq, usec, sec; | |
237 | ||
bed583f7 | 238 | /* Hold xtime_lock and adjust timeval. */ |
1da177e4 LT |
239 | do { |
240 | seq = read_seqbegin_irqsave(&xtime_lock, flags); | |
241 | usec = gettimeoffset(); | |
242 | sec = xtime.tv_sec; | |
243 | usec += (xtime.tv_nsec / 1000); | |
244 | } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); | |
245 | ||
bed583f7 | 246 | /* Move adjusted usec's into sec's. */ |
61c34016 JB |
247 | while (usec >= USEC_PER_SEC) { |
248 | usec -= USEC_PER_SEC; | |
1da177e4 LT |
249 | ++sec; |
250 | } | |
251 | ||
bed583f7 | 252 | /* Return adjusted result. */ |
1da177e4 LT |
253 | tv->tv_sec = sec; |
254 | tv->tv_usec = usec; | |
255 | } | |
256 | ||
257 | EXPORT_SYMBOL(do_gettimeofday); | |
258 | ||
259 | int | |
260 | do_settimeofday (struct timespec *tv) | |
261 | { | |
262 | time_t wtm_sec, sec = tv->tv_sec; | |
263 | long wtm_nsec, nsec = tv->tv_nsec; | |
264 | ||
265 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
266 | return -EINVAL; | |
267 | ||
268 | write_seqlock_irq(&xtime_lock); | |
269 | { | |
270 | /* | |
271 | * This is revolting. We need to set "xtime" | |
272 | * correctly. However, the value in this location is | |
273 | * the value at the most recent update of wall time. | |
274 | * Discover what correction gettimeofday would have | |
275 | * done, and then undo it! | |
276 | */ | |
277 | nsec -= gettimeoffset() * 1000; | |
278 | ||
279 | wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); | |
280 | wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); | |
281 | ||
282 | set_normalized_timespec(&xtime, sec, nsec); | |
283 | set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); | |
284 | ||
b149ee22 | 285 | ntp_clear(); |
1da177e4 LT |
286 | } |
287 | write_sequnlock_irq(&xtime_lock); | |
288 | clock_was_set(); | |
289 | return 0; | |
290 | } | |
291 | EXPORT_SYMBOL(do_settimeofday); | |
292 | ||
293 | /* | |
294 | * XXX: We can do better than this. | |
295 | * Returns nanoseconds | |
296 | */ | |
297 | ||
298 | unsigned long long sched_clock(void) | |
299 | { | |
300 | return (unsigned long long)jiffies * (1000000000 / HZ); | |
301 | } | |
302 | ||
303 | ||
56f335c8 GG |
304 | void __init start_cpu_itimer(void) |
305 | { | |
306 | unsigned int cpu = smp_processor_id(); | |
307 | unsigned long next_tick = mfctl(16) + clocktick; | |
308 | ||
309 | mtctl(next_tick, 16); /* kick off Interval Timer (CR16) */ | |
310 | ||
311 | cpu_data[cpu].it_value = next_tick; | |
312 | } | |
313 | ||
1da177e4 LT |
314 | void __init time_init(void) |
315 | { | |
1da177e4 LT |
316 | static struct pdc_tod tod_data; |
317 | ||
318 | clocktick = (100 * PAGE0->mem_10msec) / HZ; | |
1da177e4 | 319 | |
56f335c8 | 320 | start_cpu_itimer(); /* get CPU 0 started */ |
1da177e4 | 321 | |
09690b18 KM |
322 | if (pdc_tod_read(&tod_data) == 0) { |
323 | unsigned long flags; | |
324 | ||
325 | write_seqlock_irqsave(&xtime_lock, flags); | |
1da177e4 LT |
326 | xtime.tv_sec = tod_data.tod_sec; |
327 | xtime.tv_nsec = tod_data.tod_usec * 1000; | |
328 | set_normalized_timespec(&wall_to_monotonic, | |
329 | -xtime.tv_sec, -xtime.tv_nsec); | |
09690b18 | 330 | write_sequnlock_irqrestore(&xtime_lock, flags); |
1da177e4 LT |
331 | } else { |
332 | printk(KERN_ERR "Error reading tod clock\n"); | |
333 | xtime.tv_sec = 0; | |
334 | xtime.tv_nsec = 0; | |
335 | } | |
336 | } | |
337 |