time.c 33 KB

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  1. /*
  2. * Common time routines among all ppc machines.
  3. *
  4. * Written by Cort Dougan (cort@cs.nmt.edu) to merge
  5. * Paul Mackerras' version and mine for PReP and Pmac.
  6. * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
  7. * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
  8. *
  9. * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
  10. * to make clock more stable (2.4.0-test5). The only thing
  11. * that this code assumes is that the timebases have been synchronized
  12. * by firmware on SMP and are never stopped (never do sleep
  13. * on SMP then, nap and doze are OK).
  14. *
  15. * Speeded up do_gettimeofday by getting rid of references to
  16. * xtime (which required locks for consistency). (mikejc@us.ibm.com)
  17. *
  18. * TODO (not necessarily in this file):
  19. * - improve precision and reproducibility of timebase frequency
  20. * measurement at boot time. (for iSeries, we calibrate the timebase
  21. * against the Titan chip's clock.)
  22. * - for astronomical applications: add a new function to get
  23. * non ambiguous timestamps even around leap seconds. This needs
  24. * a new timestamp format and a good name.
  25. *
  26. * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
  27. * "A Kernel Model for Precision Timekeeping" by Dave Mills
  28. *
  29. * This program is free software; you can redistribute it and/or
  30. * modify it under the terms of the GNU General Public License
  31. * as published by the Free Software Foundation; either version
  32. * 2 of the License, or (at your option) any later version.
  33. */
  34. #include <linux/errno.h>
  35. #include <linux/module.h>
  36. #include <linux/sched.h>
  37. #include <linux/kernel.h>
  38. #include <linux/param.h>
  39. #include <linux/string.h>
  40. #include <linux/mm.h>
  41. #include <linux/interrupt.h>
  42. #include <linux/timex.h>
  43. #include <linux/kernel_stat.h>
  44. #include <linux/time.h>
  45. #include <linux/init.h>
  46. #include <linux/profile.h>
  47. #include <linux/cpu.h>
  48. #include <linux/security.h>
  49. #include <linux/percpu.h>
  50. #include <linux/rtc.h>
  51. #include <linux/jiffies.h>
  52. #include <linux/posix-timers.h>
  53. #include <asm/io.h>
  54. #include <asm/processor.h>
  55. #include <asm/nvram.h>
  56. #include <asm/cache.h>
  57. #include <asm/machdep.h>
  58. #include <asm/uaccess.h>
  59. #include <asm/time.h>
  60. #include <asm/prom.h>
  61. #include <asm/irq.h>
  62. #include <asm/div64.h>
  63. #include <asm/smp.h>
  64. #include <asm/vdso_datapage.h>
  65. #ifdef CONFIG_PPC64
  66. #include <asm/firmware.h>
  67. #endif
  68. #ifdef CONFIG_PPC_ISERIES
  69. #include <asm/iseries/it_lp_queue.h>
  70. #include <asm/iseries/hv_call_xm.h>
  71. #endif
  72. #include <asm/smp.h>
  73. /* keep track of when we need to update the rtc */
  74. time_t last_rtc_update;
  75. #ifdef CONFIG_PPC_ISERIES
  76. unsigned long iSeries_recal_titan = 0;
  77. unsigned long iSeries_recal_tb = 0;
  78. static unsigned long first_settimeofday = 1;
  79. #endif
  80. /* The decrementer counts down by 128 every 128ns on a 601. */
  81. #define DECREMENTER_COUNT_601 (1000000000 / HZ)
  82. #define XSEC_PER_SEC (1024*1024)
  83. #ifdef CONFIG_PPC64
  84. #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
  85. #else
  86. /* compute ((xsec << 12) * max) >> 32 */
  87. #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
  88. #endif
  89. unsigned long tb_ticks_per_jiffy;
  90. unsigned long tb_ticks_per_usec = 100; /* sane default */
  91. EXPORT_SYMBOL(tb_ticks_per_usec);
  92. unsigned long tb_ticks_per_sec;
  93. EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
  94. u64 tb_to_xs;
  95. unsigned tb_to_us;
  96. #define TICKLEN_SCALE TICK_LENGTH_SHIFT
  97. u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
  98. u64 ticklen_to_xs; /* 0.64 fraction */
  99. /* If last_tick_len corresponds to about 1/HZ seconds, then
  100. last_tick_len << TICKLEN_SHIFT will be about 2^63. */
  101. #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
  102. DEFINE_SPINLOCK(rtc_lock);
  103. EXPORT_SYMBOL_GPL(rtc_lock);
  104. u64 tb_to_ns_scale;
  105. unsigned tb_to_ns_shift;
  106. struct gettimeofday_struct do_gtod;
  107. extern unsigned long wall_jiffies;
  108. extern struct timezone sys_tz;
  109. static long timezone_offset;
  110. unsigned long ppc_proc_freq;
  111. unsigned long ppc_tb_freq;
  112. static u64 tb_last_jiffy __cacheline_aligned_in_smp;
  113. static DEFINE_PER_CPU(u64, last_jiffy);
  114. #ifdef CONFIG_VIRT_CPU_ACCOUNTING
  115. /*
  116. * Factors for converting from cputime_t (timebase ticks) to
  117. * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
  118. * These are all stored as 0.64 fixed-point binary fractions.
  119. */
  120. u64 __cputime_jiffies_factor;
  121. EXPORT_SYMBOL(__cputime_jiffies_factor);
  122. u64 __cputime_msec_factor;
  123. EXPORT_SYMBOL(__cputime_msec_factor);
  124. u64 __cputime_sec_factor;
  125. EXPORT_SYMBOL(__cputime_sec_factor);
  126. u64 __cputime_clockt_factor;
  127. EXPORT_SYMBOL(__cputime_clockt_factor);
  128. static void calc_cputime_factors(void)
  129. {
  130. struct div_result res;
  131. div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
  132. __cputime_jiffies_factor = res.result_low;
  133. div128_by_32(1000, 0, tb_ticks_per_sec, &res);
  134. __cputime_msec_factor = res.result_low;
  135. div128_by_32(1, 0, tb_ticks_per_sec, &res);
  136. __cputime_sec_factor = res.result_low;
  137. div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
  138. __cputime_clockt_factor = res.result_low;
  139. }
  140. /*
  141. * Read the PURR on systems that have it, otherwise the timebase.
  142. */
  143. static u64 read_purr(void)
  144. {
  145. if (cpu_has_feature(CPU_FTR_PURR))
  146. return mfspr(SPRN_PURR);
  147. return mftb();
  148. }
  149. /*
  150. * Account time for a transition between system, hard irq
  151. * or soft irq state.
  152. */
  153. void account_system_vtime(struct task_struct *tsk)
  154. {
  155. u64 now, delta;
  156. unsigned long flags;
  157. local_irq_save(flags);
  158. now = read_purr();
  159. delta = now - get_paca()->startpurr;
  160. get_paca()->startpurr = now;
  161. if (!in_interrupt()) {
  162. delta += get_paca()->system_time;
  163. get_paca()->system_time = 0;
  164. }
  165. account_system_time(tsk, 0, delta);
  166. local_irq_restore(flags);
  167. }
  168. /*
  169. * Transfer the user and system times accumulated in the paca
  170. * by the exception entry and exit code to the generic process
  171. * user and system time records.
  172. * Must be called with interrupts disabled.
  173. */
  174. void account_process_vtime(struct task_struct *tsk)
  175. {
  176. cputime_t utime;
  177. utime = get_paca()->user_time;
  178. get_paca()->user_time = 0;
  179. account_user_time(tsk, utime);
  180. }
  181. static void account_process_time(struct pt_regs *regs)
  182. {
  183. int cpu = smp_processor_id();
  184. account_process_vtime(current);
  185. run_local_timers();
  186. if (rcu_pending(cpu))
  187. rcu_check_callbacks(cpu, user_mode(regs));
  188. scheduler_tick();
  189. run_posix_cpu_timers(current);
  190. }
  191. #ifdef CONFIG_PPC_SPLPAR
  192. /*
  193. * Stuff for accounting stolen time.
  194. */
  195. struct cpu_purr_data {
  196. int initialized; /* thread is running */
  197. u64 tb0; /* timebase at origin time */
  198. u64 purr0; /* PURR at origin time */
  199. u64 tb; /* last TB value read */
  200. u64 purr; /* last PURR value read */
  201. u64 stolen; /* stolen time so far */
  202. spinlock_t lock;
  203. };
  204. static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
  205. static void snapshot_tb_and_purr(void *data)
  206. {
  207. struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
  208. p->tb0 = mftb();
  209. p->purr0 = mfspr(SPRN_PURR);
  210. p->tb = p->tb0;
  211. p->purr = 0;
  212. wmb();
  213. p->initialized = 1;
  214. }
  215. /*
  216. * Called during boot when all cpus have come up.
  217. */
  218. void snapshot_timebases(void)
  219. {
  220. int cpu;
  221. if (!cpu_has_feature(CPU_FTR_PURR))
  222. return;
  223. for_each_possible_cpu(cpu)
  224. spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock);
  225. on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1);
  226. }
  227. void calculate_steal_time(void)
  228. {
  229. u64 tb, purr, t0;
  230. s64 stolen;
  231. struct cpu_purr_data *p0, *pme, *phim;
  232. int cpu;
  233. if (!cpu_has_feature(CPU_FTR_PURR))
  234. return;
  235. cpu = smp_processor_id();
  236. pme = &per_cpu(cpu_purr_data, cpu);
  237. if (!pme->initialized)
  238. return; /* this can happen in early boot */
  239. p0 = &per_cpu(cpu_purr_data, cpu & ~1);
  240. phim = &per_cpu(cpu_purr_data, cpu ^ 1);
  241. spin_lock(&p0->lock);
  242. tb = mftb();
  243. purr = mfspr(SPRN_PURR) - pme->purr0;
  244. if (!phim->initialized || !cpu_online(cpu ^ 1)) {
  245. stolen = (tb - pme->tb) - (purr - pme->purr);
  246. } else {
  247. t0 = pme->tb0;
  248. if (phim->tb0 < t0)
  249. t0 = phim->tb0;
  250. stolen = phim->tb - t0 - phim->purr - purr - p0->stolen;
  251. }
  252. if (stolen > 0) {
  253. account_steal_time(current, stolen);
  254. p0->stolen += stolen;
  255. }
  256. pme->tb = tb;
  257. pme->purr = purr;
  258. spin_unlock(&p0->lock);
  259. }
  260. /*
  261. * Must be called before the cpu is added to the online map when
  262. * a cpu is being brought up at runtime.
  263. */
  264. static void snapshot_purr(void)
  265. {
  266. int cpu;
  267. u64 purr;
  268. struct cpu_purr_data *p0, *pme, *phim;
  269. unsigned long flags;
  270. if (!cpu_has_feature(CPU_FTR_PURR))
  271. return;
  272. cpu = smp_processor_id();
  273. pme = &per_cpu(cpu_purr_data, cpu);
  274. p0 = &per_cpu(cpu_purr_data, cpu & ~1);
  275. phim = &per_cpu(cpu_purr_data, cpu ^ 1);
  276. spin_lock_irqsave(&p0->lock, flags);
  277. pme->tb = pme->tb0 = mftb();
  278. purr = mfspr(SPRN_PURR);
  279. if (!phim->initialized) {
  280. pme->purr = 0;
  281. pme->purr0 = purr;
  282. } else {
  283. /* set p->purr and p->purr0 for no change in p0->stolen */
  284. pme->purr = phim->tb - phim->tb0 - phim->purr - p0->stolen;
  285. pme->purr0 = purr - pme->purr;
  286. }
  287. pme->initialized = 1;
  288. spin_unlock_irqrestore(&p0->lock, flags);
  289. }
  290. #endif /* CONFIG_PPC_SPLPAR */
  291. #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
  292. #define calc_cputime_factors()
  293. #define account_process_time(regs) update_process_times(user_mode(regs))
  294. #define calculate_steal_time() do { } while (0)
  295. #endif
  296. #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
  297. #define snapshot_purr() do { } while (0)
  298. #endif
  299. /*
  300. * Called when a cpu comes up after the system has finished booting,
  301. * i.e. as a result of a hotplug cpu action.
  302. */
  303. void snapshot_timebase(void)
  304. {
  305. __get_cpu_var(last_jiffy) = get_tb();
  306. snapshot_purr();
  307. }
  308. void __delay(unsigned long loops)
  309. {
  310. unsigned long start;
  311. int diff;
  312. if (__USE_RTC()) {
  313. start = get_rtcl();
  314. do {
  315. /* the RTCL register wraps at 1000000000 */
  316. diff = get_rtcl() - start;
  317. if (diff < 0)
  318. diff += 1000000000;
  319. } while (diff < loops);
  320. } else {
  321. start = get_tbl();
  322. while (get_tbl() - start < loops)
  323. HMT_low();
  324. HMT_medium();
  325. }
  326. }
  327. EXPORT_SYMBOL(__delay);
  328. void udelay(unsigned long usecs)
  329. {
  330. __delay(tb_ticks_per_usec * usecs);
  331. }
  332. EXPORT_SYMBOL(udelay);
  333. static __inline__ void timer_check_rtc(void)
  334. {
  335. /*
  336. * update the rtc when needed, this should be performed on the
  337. * right fraction of a second. Half or full second ?
  338. * Full second works on mk48t59 clocks, others need testing.
  339. * Note that this update is basically only used through
  340. * the adjtimex system calls. Setting the HW clock in
  341. * any other way is a /dev/rtc and userland business.
  342. * This is still wrong by -0.5/+1.5 jiffies because of the
  343. * timer interrupt resolution and possible delay, but here we
  344. * hit a quantization limit which can only be solved by higher
  345. * resolution timers and decoupling time management from timer
  346. * interrupts. This is also wrong on the clocks
  347. * which require being written at the half second boundary.
  348. * We should have an rtc call that only sets the minutes and
  349. * seconds like on Intel to avoid problems with non UTC clocks.
  350. */
  351. if (ppc_md.set_rtc_time && ntp_synced() &&
  352. xtime.tv_sec - last_rtc_update >= 659 &&
  353. abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ) {
  354. struct rtc_time tm;
  355. to_tm(xtime.tv_sec + 1 + timezone_offset, &tm);
  356. tm.tm_year -= 1900;
  357. tm.tm_mon -= 1;
  358. if (ppc_md.set_rtc_time(&tm) == 0)
  359. last_rtc_update = xtime.tv_sec + 1;
  360. else
  361. /* Try again one minute later */
  362. last_rtc_update += 60;
  363. }
  364. }
  365. /*
  366. * This version of gettimeofday has microsecond resolution.
  367. */
  368. static inline void __do_gettimeofday(struct timeval *tv)
  369. {
  370. unsigned long sec, usec;
  371. u64 tb_ticks, xsec;
  372. struct gettimeofday_vars *temp_varp;
  373. u64 temp_tb_to_xs, temp_stamp_xsec;
  374. /*
  375. * These calculations are faster (gets rid of divides)
  376. * if done in units of 1/2^20 rather than microseconds.
  377. * The conversion to microseconds at the end is done
  378. * without a divide (and in fact, without a multiply)
  379. */
  380. temp_varp = do_gtod.varp;
  381. /* Sampling the time base must be done after loading
  382. * do_gtod.varp in order to avoid racing with update_gtod.
  383. */
  384. data_barrier(temp_varp);
  385. tb_ticks = get_tb() - temp_varp->tb_orig_stamp;
  386. temp_tb_to_xs = temp_varp->tb_to_xs;
  387. temp_stamp_xsec = temp_varp->stamp_xsec;
  388. xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
  389. sec = xsec / XSEC_PER_SEC;
  390. usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
  391. usec = SCALE_XSEC(usec, 1000000);
  392. tv->tv_sec = sec;
  393. tv->tv_usec = usec;
  394. }
  395. void do_gettimeofday(struct timeval *tv)
  396. {
  397. if (__USE_RTC()) {
  398. /* do this the old way */
  399. unsigned long flags, seq;
  400. unsigned int sec, nsec, usec;
  401. do {
  402. seq = read_seqbegin_irqsave(&xtime_lock, flags);
  403. sec = xtime.tv_sec;
  404. nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy);
  405. } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
  406. usec = nsec / 1000;
  407. while (usec >= 1000000) {
  408. usec -= 1000000;
  409. ++sec;
  410. }
  411. tv->tv_sec = sec;
  412. tv->tv_usec = usec;
  413. return;
  414. }
  415. __do_gettimeofday(tv);
  416. }
  417. EXPORT_SYMBOL(do_gettimeofday);
  418. /*
  419. * There are two copies of tb_to_xs and stamp_xsec so that no
  420. * lock is needed to access and use these values in
  421. * do_gettimeofday. We alternate the copies and as long as a
  422. * reasonable time elapses between changes, there will never
  423. * be inconsistent values. ntpd has a minimum of one minute
  424. * between updates.
  425. */
  426. static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
  427. u64 new_tb_to_xs)
  428. {
  429. unsigned temp_idx;
  430. struct gettimeofday_vars *temp_varp;
  431. temp_idx = (do_gtod.var_idx == 0);
  432. temp_varp = &do_gtod.vars[temp_idx];
  433. temp_varp->tb_to_xs = new_tb_to_xs;
  434. temp_varp->tb_orig_stamp = new_tb_stamp;
  435. temp_varp->stamp_xsec = new_stamp_xsec;
  436. smp_mb();
  437. do_gtod.varp = temp_varp;
  438. do_gtod.var_idx = temp_idx;
  439. /*
  440. * tb_update_count is used to allow the userspace gettimeofday code
  441. * to assure itself that it sees a consistent view of the tb_to_xs and
  442. * stamp_xsec variables. It reads the tb_update_count, then reads
  443. * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
  444. * the two values of tb_update_count match and are even then the
  445. * tb_to_xs and stamp_xsec values are consistent. If not, then it
  446. * loops back and reads them again until this criteria is met.
  447. * We expect the caller to have done the first increment of
  448. * vdso_data->tb_update_count already.
  449. */
  450. vdso_data->tb_orig_stamp = new_tb_stamp;
  451. vdso_data->stamp_xsec = new_stamp_xsec;
  452. vdso_data->tb_to_xs = new_tb_to_xs;
  453. vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
  454. vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
  455. smp_wmb();
  456. ++(vdso_data->tb_update_count);
  457. }
  458. /*
  459. * When the timebase - tb_orig_stamp gets too big, we do a manipulation
  460. * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
  461. * difference tb - tb_orig_stamp small enough to always fit inside a
  462. * 32 bits number. This is a requirement of our fast 32 bits userland
  463. * implementation in the vdso. If we "miss" a call to this function
  464. * (interrupt latency, CPU locked in a spinlock, ...) and we end up
  465. * with a too big difference, then the vdso will fallback to calling
  466. * the syscall
  467. */
  468. static __inline__ void timer_recalc_offset(u64 cur_tb)
  469. {
  470. unsigned long offset;
  471. u64 new_stamp_xsec;
  472. u64 tlen, t2x;
  473. u64 tb, xsec_old, xsec_new;
  474. struct gettimeofday_vars *varp;
  475. if (__USE_RTC())
  476. return;
  477. tlen = current_tick_length();
  478. offset = cur_tb - do_gtod.varp->tb_orig_stamp;
  479. if (tlen == last_tick_len && offset < 0x80000000u)
  480. return;
  481. if (tlen != last_tick_len) {
  482. t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
  483. last_tick_len = tlen;
  484. } else
  485. t2x = do_gtod.varp->tb_to_xs;
  486. new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
  487. do_div(new_stamp_xsec, 1000000000);
  488. new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
  489. ++vdso_data->tb_update_count;
  490. smp_mb();
  491. /*
  492. * Make sure time doesn't go backwards for userspace gettimeofday.
  493. */
  494. tb = get_tb();
  495. varp = do_gtod.varp;
  496. xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs)
  497. + varp->stamp_xsec;
  498. xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec;
  499. if (xsec_new < xsec_old)
  500. new_stamp_xsec += xsec_old - xsec_new;
  501. update_gtod(cur_tb, new_stamp_xsec, t2x);
  502. }
  503. #ifdef CONFIG_SMP
  504. unsigned long profile_pc(struct pt_regs *regs)
  505. {
  506. unsigned long pc = instruction_pointer(regs);
  507. if (in_lock_functions(pc))
  508. return regs->link;
  509. return pc;
  510. }
  511. EXPORT_SYMBOL(profile_pc);
  512. #endif
  513. #ifdef CONFIG_PPC_ISERIES
  514. /*
  515. * This function recalibrates the timebase based on the 49-bit time-of-day
  516. * value in the Titan chip. The Titan is much more accurate than the value
  517. * returned by the service processor for the timebase frequency.
  518. */
  519. static void iSeries_tb_recal(void)
  520. {
  521. struct div_result divres;
  522. unsigned long titan, tb;
  523. tb = get_tb();
  524. titan = HvCallXm_loadTod();
  525. if ( iSeries_recal_titan ) {
  526. unsigned long tb_ticks = tb - iSeries_recal_tb;
  527. unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
  528. unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
  529. unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
  530. long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
  531. char sign = '+';
  532. /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
  533. new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
  534. if ( tick_diff < 0 ) {
  535. tick_diff = -tick_diff;
  536. sign = '-';
  537. }
  538. if ( tick_diff ) {
  539. if ( tick_diff < tb_ticks_per_jiffy/25 ) {
  540. printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
  541. new_tb_ticks_per_jiffy, sign, tick_diff );
  542. tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
  543. tb_ticks_per_sec = new_tb_ticks_per_sec;
  544. calc_cputime_factors();
  545. div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
  546. do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
  547. tb_to_xs = divres.result_low;
  548. do_gtod.varp->tb_to_xs = tb_to_xs;
  549. vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
  550. vdso_data->tb_to_xs = tb_to_xs;
  551. }
  552. else {
  553. printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
  554. " new tb_ticks_per_jiffy = %lu\n"
  555. " old tb_ticks_per_jiffy = %lu\n",
  556. new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
  557. }
  558. }
  559. }
  560. iSeries_recal_titan = titan;
  561. iSeries_recal_tb = tb;
  562. }
  563. #endif
  564. /*
  565. * For iSeries shared processors, we have to let the hypervisor
  566. * set the hardware decrementer. We set a virtual decrementer
  567. * in the lppaca and call the hypervisor if the virtual
  568. * decrementer is less than the current value in the hardware
  569. * decrementer. (almost always the new decrementer value will
  570. * be greater than the current hardware decementer so the hypervisor
  571. * call will not be needed)
  572. */
  573. /*
  574. * timer_interrupt - gets called when the decrementer overflows,
  575. * with interrupts disabled.
  576. */
  577. void timer_interrupt(struct pt_regs * regs)
  578. {
  579. int next_dec;
  580. int cpu = smp_processor_id();
  581. unsigned long ticks;
  582. u64 tb_next_jiffy;
  583. #ifdef CONFIG_PPC32
  584. if (atomic_read(&ppc_n_lost_interrupts) != 0)
  585. do_IRQ(regs);
  586. #endif
  587. irq_enter();
  588. profile_tick(CPU_PROFILING, regs);
  589. calculate_steal_time();
  590. #ifdef CONFIG_PPC_ISERIES
  591. get_lppaca()->int_dword.fields.decr_int = 0;
  592. #endif
  593. while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu)))
  594. >= tb_ticks_per_jiffy) {
  595. /* Update last_jiffy */
  596. per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
  597. /* Handle RTCL overflow on 601 */
  598. if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000)
  599. per_cpu(last_jiffy, cpu) -= 1000000000;
  600. /*
  601. * We cannot disable the decrementer, so in the period
  602. * between this cpu's being marked offline in cpu_online_map
  603. * and calling stop-self, it is taking timer interrupts.
  604. * Avoid calling into the scheduler rebalancing code if this
  605. * is the case.
  606. */
  607. if (!cpu_is_offline(cpu))
  608. account_process_time(regs);
  609. /*
  610. * No need to check whether cpu is offline here; boot_cpuid
  611. * should have been fixed up by now.
  612. */
  613. if (cpu != boot_cpuid)
  614. continue;
  615. write_seqlock(&xtime_lock);
  616. tb_next_jiffy = tb_last_jiffy + tb_ticks_per_jiffy;
  617. if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
  618. tb_last_jiffy = tb_next_jiffy;
  619. do_timer(regs);
  620. timer_recalc_offset(tb_last_jiffy);
  621. timer_check_rtc();
  622. }
  623. write_sequnlock(&xtime_lock);
  624. }
  625. next_dec = tb_ticks_per_jiffy - ticks;
  626. set_dec(next_dec);
  627. #ifdef CONFIG_PPC_ISERIES
  628. if (hvlpevent_is_pending())
  629. process_hvlpevents(regs);
  630. #endif
  631. #ifdef CONFIG_PPC64
  632. /* collect purr register values often, for accurate calculations */
  633. if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
  634. struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
  635. cu->current_tb = mfspr(SPRN_PURR);
  636. }
  637. #endif
  638. irq_exit();
  639. }
  640. void wakeup_decrementer(void)
  641. {
  642. unsigned long ticks;
  643. /*
  644. * The timebase gets saved on sleep and restored on wakeup,
  645. * so all we need to do is to reset the decrementer.
  646. */
  647. ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
  648. if (ticks < tb_ticks_per_jiffy)
  649. ticks = tb_ticks_per_jiffy - ticks;
  650. else
  651. ticks = 1;
  652. set_dec(ticks);
  653. }
  654. #ifdef CONFIG_SMP
  655. void __init smp_space_timers(unsigned int max_cpus)
  656. {
  657. int i;
  658. unsigned long half = tb_ticks_per_jiffy / 2;
  659. unsigned long offset = tb_ticks_per_jiffy / max_cpus;
  660. u64 previous_tb = per_cpu(last_jiffy, boot_cpuid);
  661. /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
  662. previous_tb -= tb_ticks_per_jiffy;
  663. /*
  664. * The stolen time calculation for POWER5 shared-processor LPAR
  665. * systems works better if the two threads' timebase interrupts
  666. * are staggered by half a jiffy with respect to each other.
  667. */
  668. for_each_possible_cpu(i) {
  669. if (i == boot_cpuid)
  670. continue;
  671. if (i == (boot_cpuid ^ 1))
  672. per_cpu(last_jiffy, i) =
  673. per_cpu(last_jiffy, boot_cpuid) - half;
  674. else if (i & 1)
  675. per_cpu(last_jiffy, i) =
  676. per_cpu(last_jiffy, i ^ 1) + half;
  677. else {
  678. previous_tb += offset;
  679. per_cpu(last_jiffy, i) = previous_tb;
  680. }
  681. }
  682. }
  683. #endif
  684. /*
  685. * Scheduler clock - returns current time in nanosec units.
  686. *
  687. * Note: mulhdu(a, b) (multiply high double unsigned) returns
  688. * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
  689. * are 64-bit unsigned numbers.
  690. */
  691. unsigned long long sched_clock(void)
  692. {
  693. if (__USE_RTC())
  694. return get_rtc();
  695. return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
  696. }
  697. int do_settimeofday(struct timespec *tv)
  698. {
  699. time_t wtm_sec, new_sec = tv->tv_sec;
  700. long wtm_nsec, new_nsec = tv->tv_nsec;
  701. unsigned long flags;
  702. u64 new_xsec;
  703. unsigned long tb_delta;
  704. if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
  705. return -EINVAL;
  706. write_seqlock_irqsave(&xtime_lock, flags);
  707. /*
  708. * Updating the RTC is not the job of this code. If the time is
  709. * stepped under NTP, the RTC will be updated after STA_UNSYNC
  710. * is cleared. Tools like clock/hwclock either copy the RTC
  711. * to the system time, in which case there is no point in writing
  712. * to the RTC again, or write to the RTC but then they don't call
  713. * settimeofday to perform this operation.
  714. */
  715. #ifdef CONFIG_PPC_ISERIES
  716. if (first_settimeofday) {
  717. iSeries_tb_recal();
  718. first_settimeofday = 0;
  719. }
  720. #endif
  721. /* Make userspace gettimeofday spin until we're done. */
  722. ++vdso_data->tb_update_count;
  723. smp_mb();
  724. /*
  725. * Subtract off the number of nanoseconds since the
  726. * beginning of the last tick.
  727. * Note that since we don't increment jiffies_64 anywhere other
  728. * than in do_timer (since we don't have a lost tick problem),
  729. * wall_jiffies will always be the same as jiffies,
  730. * and therefore the (jiffies - wall_jiffies) computation
  731. * has been removed.
  732. */
  733. tb_delta = tb_ticks_since(tb_last_jiffy);
  734. tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
  735. new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
  736. wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
  737. wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
  738. set_normalized_timespec(&xtime, new_sec, new_nsec);
  739. set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
  740. /* In case of a large backwards jump in time with NTP, we want the
  741. * clock to be updated as soon as the PLL is again in lock.
  742. */
  743. last_rtc_update = new_sec - 658;
  744. ntp_clear();
  745. new_xsec = xtime.tv_nsec;
  746. if (new_xsec != 0) {
  747. new_xsec *= XSEC_PER_SEC;
  748. do_div(new_xsec, NSEC_PER_SEC);
  749. }
  750. new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
  751. update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
  752. vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
  753. vdso_data->tz_dsttime = sys_tz.tz_dsttime;
  754. write_sequnlock_irqrestore(&xtime_lock, flags);
  755. clock_was_set();
  756. return 0;
  757. }
  758. EXPORT_SYMBOL(do_settimeofday);
  759. static int __init get_freq(char *name, int cells, unsigned long *val)
  760. {
  761. struct device_node *cpu;
  762. const unsigned int *fp;
  763. int found = 0;
  764. /* The cpu node should have timebase and clock frequency properties */
  765. cpu = of_find_node_by_type(NULL, "cpu");
  766. if (cpu) {
  767. fp = get_property(cpu, name, NULL);
  768. if (fp) {
  769. found = 1;
  770. *val = of_read_ulong(fp, cells);
  771. }
  772. of_node_put(cpu);
  773. }
  774. return found;
  775. }
  776. void __init generic_calibrate_decr(void)
  777. {
  778. ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
  779. if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
  780. !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
  781. printk(KERN_ERR "WARNING: Estimating decrementer frequency "
  782. "(not found)\n");
  783. }
  784. ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
  785. if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
  786. !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
  787. printk(KERN_ERR "WARNING: Estimating processor frequency "
  788. "(not found)\n");
  789. }
  790. #ifdef CONFIG_BOOKE
  791. /* Set the time base to zero */
  792. mtspr(SPRN_TBWL, 0);
  793. mtspr(SPRN_TBWU, 0);
  794. /* Clear any pending timer interrupts */
  795. mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
  796. /* Enable decrementer interrupt */
  797. mtspr(SPRN_TCR, TCR_DIE);
  798. #endif
  799. }
  800. unsigned long get_boot_time(void)
  801. {
  802. struct rtc_time tm;
  803. if (ppc_md.get_boot_time)
  804. return ppc_md.get_boot_time();
  805. if (!ppc_md.get_rtc_time)
  806. return 0;
  807. ppc_md.get_rtc_time(&tm);
  808. return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
  809. tm.tm_hour, tm.tm_min, tm.tm_sec);
  810. }
  811. /* This function is only called on the boot processor */
  812. void __init time_init(void)
  813. {
  814. unsigned long flags;
  815. unsigned long tm = 0;
  816. struct div_result res;
  817. u64 scale, x;
  818. unsigned shift;
  819. if (ppc_md.time_init != NULL)
  820. timezone_offset = ppc_md.time_init();
  821. if (__USE_RTC()) {
  822. /* 601 processor: dec counts down by 128 every 128ns */
  823. ppc_tb_freq = 1000000000;
  824. tb_last_jiffy = get_rtcl();
  825. } else {
  826. /* Normal PowerPC with timebase register */
  827. ppc_md.calibrate_decr();
  828. printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
  829. ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
  830. printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
  831. ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
  832. tb_last_jiffy = get_tb();
  833. }
  834. tb_ticks_per_jiffy = ppc_tb_freq / HZ;
  835. tb_ticks_per_sec = ppc_tb_freq;
  836. tb_ticks_per_usec = ppc_tb_freq / 1000000;
  837. tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
  838. calc_cputime_factors();
  839. /*
  840. * Calculate the length of each tick in ns. It will not be
  841. * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
  842. * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
  843. * rounded up.
  844. */
  845. x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
  846. do_div(x, ppc_tb_freq);
  847. tick_nsec = x;
  848. last_tick_len = x << TICKLEN_SCALE;
  849. /*
  850. * Compute ticklen_to_xs, which is a factor which gets multiplied
  851. * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
  852. * It is computed as:
  853. * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
  854. * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
  855. * which turns out to be N = 51 - SHIFT_HZ.
  856. * This gives the result as a 0.64 fixed-point fraction.
  857. * That value is reduced by an offset amounting to 1 xsec per
  858. * 2^31 timebase ticks to avoid problems with time going backwards
  859. * by 1 xsec when we do timer_recalc_offset due to losing the
  860. * fractional xsec. That offset is equal to ppc_tb_freq/2^51
  861. * since there are 2^20 xsec in a second.
  862. */
  863. div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
  864. tb_ticks_per_jiffy << SHIFT_HZ, &res);
  865. div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
  866. ticklen_to_xs = res.result_low;
  867. /* Compute tb_to_xs from tick_nsec */
  868. tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
  869. /*
  870. * Compute scale factor for sched_clock.
  871. * The calibrate_decr() function has set tb_ticks_per_sec,
  872. * which is the timebase frequency.
  873. * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
  874. * the 128-bit result as a 64.64 fixed-point number.
  875. * We then shift that number right until it is less than 1.0,
  876. * giving us the scale factor and shift count to use in
  877. * sched_clock().
  878. */
  879. div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
  880. scale = res.result_low;
  881. for (shift = 0; res.result_high != 0; ++shift) {
  882. scale = (scale >> 1) | (res.result_high << 63);
  883. res.result_high >>= 1;
  884. }
  885. tb_to_ns_scale = scale;
  886. tb_to_ns_shift = shift;
  887. tm = get_boot_time();
  888. write_seqlock_irqsave(&xtime_lock, flags);
  889. /* If platform provided a timezone (pmac), we correct the time */
  890. if (timezone_offset) {
  891. sys_tz.tz_minuteswest = -timezone_offset / 60;
  892. sys_tz.tz_dsttime = 0;
  893. tm -= timezone_offset;
  894. }
  895. xtime.tv_sec = tm;
  896. xtime.tv_nsec = 0;
  897. do_gtod.varp = &do_gtod.vars[0];
  898. do_gtod.var_idx = 0;
  899. do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
  900. __get_cpu_var(last_jiffy) = tb_last_jiffy;
  901. do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
  902. do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
  903. do_gtod.varp->tb_to_xs = tb_to_xs;
  904. do_gtod.tb_to_us = tb_to_us;
  905. vdso_data->tb_orig_stamp = tb_last_jiffy;
  906. vdso_data->tb_update_count = 0;
  907. vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
  908. vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
  909. vdso_data->tb_to_xs = tb_to_xs;
  910. time_freq = 0;
  911. last_rtc_update = xtime.tv_sec;
  912. set_normalized_timespec(&wall_to_monotonic,
  913. -xtime.tv_sec, -xtime.tv_nsec);
  914. write_sequnlock_irqrestore(&xtime_lock, flags);
  915. /* Not exact, but the timer interrupt takes care of this */
  916. set_dec(tb_ticks_per_jiffy);
  917. }
  918. #define FEBRUARY 2
  919. #define STARTOFTIME 1970
  920. #define SECDAY 86400L
  921. #define SECYR (SECDAY * 365)
  922. #define leapyear(year) ((year) % 4 == 0 && \
  923. ((year) % 100 != 0 || (year) % 400 == 0))
  924. #define days_in_year(a) (leapyear(a) ? 366 : 365)
  925. #define days_in_month(a) (month_days[(a) - 1])
  926. static int month_days[12] = {
  927. 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
  928. };
  929. /*
  930. * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
  931. */
  932. void GregorianDay(struct rtc_time * tm)
  933. {
  934. int leapsToDate;
  935. int lastYear;
  936. int day;
  937. int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
  938. lastYear = tm->tm_year - 1;
  939. /*
  940. * Number of leap corrections to apply up to end of last year
  941. */
  942. leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
  943. /*
  944. * This year is a leap year if it is divisible by 4 except when it is
  945. * divisible by 100 unless it is divisible by 400
  946. *
  947. * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
  948. */
  949. day = tm->tm_mon > 2 && leapyear(tm->tm_year);
  950. day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
  951. tm->tm_mday;
  952. tm->tm_wday = day % 7;
  953. }
  954. void to_tm(int tim, struct rtc_time * tm)
  955. {
  956. register int i;
  957. register long hms, day;
  958. day = tim / SECDAY;
  959. hms = tim % SECDAY;
  960. /* Hours, minutes, seconds are easy */
  961. tm->tm_hour = hms / 3600;
  962. tm->tm_min = (hms % 3600) / 60;
  963. tm->tm_sec = (hms % 3600) % 60;
  964. /* Number of years in days */
  965. for (i = STARTOFTIME; day >= days_in_year(i); i++)
  966. day -= days_in_year(i);
  967. tm->tm_year = i;
  968. /* Number of months in days left */
  969. if (leapyear(tm->tm_year))
  970. days_in_month(FEBRUARY) = 29;
  971. for (i = 1; day >= days_in_month(i); i++)
  972. day -= days_in_month(i);
  973. days_in_month(FEBRUARY) = 28;
  974. tm->tm_mon = i;
  975. /* Days are what is left over (+1) from all that. */
  976. tm->tm_mday = day + 1;
  977. /*
  978. * Determine the day of week
  979. */
  980. GregorianDay(tm);
  981. }
  982. /* Auxiliary function to compute scaling factors */
  983. /* Actually the choice of a timebase running at 1/4 the of the bus
  984. * frequency giving resolution of a few tens of nanoseconds is quite nice.
  985. * It makes this computation very precise (27-28 bits typically) which
  986. * is optimistic considering the stability of most processor clock
  987. * oscillators and the precision with which the timebase frequency
  988. * is measured but does not harm.
  989. */
  990. unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
  991. {
  992. unsigned mlt=0, tmp, err;
  993. /* No concern for performance, it's done once: use a stupid
  994. * but safe and compact method to find the multiplier.
  995. */
  996. for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
  997. if (mulhwu(inscale, mlt|tmp) < outscale)
  998. mlt |= tmp;
  999. }
  1000. /* We might still be off by 1 for the best approximation.
  1001. * A side effect of this is that if outscale is too large
  1002. * the returned value will be zero.
  1003. * Many corner cases have been checked and seem to work,
  1004. * some might have been forgotten in the test however.
  1005. */
  1006. err = inscale * (mlt+1);
  1007. if (err <= inscale/2)
  1008. mlt++;
  1009. return mlt;
  1010. }
  1011. /*
  1012. * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
  1013. * result.
  1014. */
  1015. void div128_by_32(u64 dividend_high, u64 dividend_low,
  1016. unsigned divisor, struct div_result *dr)
  1017. {
  1018. unsigned long a, b, c, d;
  1019. unsigned long w, x, y, z;
  1020. u64 ra, rb, rc;
  1021. a = dividend_high >> 32;
  1022. b = dividend_high & 0xffffffff;
  1023. c = dividend_low >> 32;
  1024. d = dividend_low & 0xffffffff;
  1025. w = a / divisor;
  1026. ra = ((u64)(a - (w * divisor)) << 32) + b;
  1027. rb = ((u64) do_div(ra, divisor) << 32) + c;
  1028. x = ra;
  1029. rc = ((u64) do_div(rb, divisor) << 32) + d;
  1030. y = rb;
  1031. do_div(rc, divisor);
  1032. z = rc;
  1033. dr->result_high = ((u64)w << 32) + x;
  1034. dr->result_low = ((u64)y << 32) + z;
  1035. }