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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2006-10-23 11:21:27 -0400
committerRalf Baechle <ralf@linux-mips.org>2006-10-31 15:13:23 -0500
commit16b7b2ac0148e839da86af8747b6fa4aad43a9b7 (patch)
tree93912ae2e9c64f71a8cca028677fd918b9edf0fa /arch/mips/kernel
parent70e46f48cb5933119712ee27945309a4bfc98282 (diff)
[MIPS] Fixup migration to GENERIC_TIME
Since we already moved to GENERIC_TIME, we should implement alternatives of old do_gettimeoffset routines to get sub-jiffies resolution from gettimeofday(). This patch includes: * MIPS clocksource support (based on works by Manish Lachwani). * remove unused gettimeoffset routines and related codes. * remove unised 64bit do_div64_32(). * simplify mips_hpt_init. (no argument needed, __init tag) * simplify c0_hpt_timer_init. (no need to write to c0_count) * remove some hpt_init routines. * mips_hpt_mask variable to specify bitmask of hpt value. * convert jmr3927_do_gettimeoffset to jmr3927_hpt_read. * convert ip27_do_gettimeoffset to ip27_hpt_read. * convert bcm1480_do_gettimeoffset to bcm1480_hpt_read. * simplify sb1250 hpt functions. (no need to subtract and shift) Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/time.c319
1 files changed, 53 insertions, 266 deletions
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index debe86c2f691..e535f86efa2f 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -11,6 +11,7 @@
11 * Free Software Foundation; either version 2 of the License, or (at your 11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version. 12 * option) any later version.
13 */ 13 */
14#include <linux/clocksource.h>
14#include <linux/types.h> 15#include <linux/types.h>
15#include <linux/kernel.h> 16#include <linux/kernel.h>
16#include <linux/init.h> 17#include <linux/init.h>
@@ -67,15 +68,9 @@ int (*rtc_mips_set_time)(unsigned long) = null_rtc_set_time;
67int (*rtc_mips_set_mmss)(unsigned long); 68int (*rtc_mips_set_mmss)(unsigned long);
68 69
69 70
70/* usecs per counter cycle, shifted to left by 32 bits */
71static unsigned int sll32_usecs_per_cycle;
72
73/* how many counter cycles in a jiffy */ 71/* how many counter cycles in a jiffy */
74static unsigned long cycles_per_jiffy __read_mostly; 72static unsigned long cycles_per_jiffy __read_mostly;
75 73
76/* Cycle counter value at the previous timer interrupt.. */
77static unsigned int timerhi, timerlo;
78
79/* expirelo is the count value for next CPU timer interrupt */ 74/* expirelo is the count value for next CPU timer interrupt */
80static unsigned int expirelo; 75static unsigned int expirelo;
81 76
@@ -93,7 +88,7 @@ static unsigned int null_hpt_read(void)
93 return 0; 88 return 0;
94} 89}
95 90
96static void null_hpt_init(unsigned int count) 91static void __init null_hpt_init(void)
97{ 92{
98 /* nothing */ 93 /* nothing */
99} 94}
@@ -128,186 +123,18 @@ static unsigned int c0_hpt_read(void)
128 return read_c0_count(); 123 return read_c0_count();
129} 124}
130 125
131/* For use solely as a high precision timer. */
132static void c0_hpt_init(unsigned int count)
133{
134 write_c0_count(read_c0_count() - count);
135}
136
137/* For use both as a high precision timer and an interrupt source. */ 126/* For use both as a high precision timer and an interrupt source. */
138static void c0_hpt_timer_init(unsigned int count) 127static void __init c0_hpt_timer_init(void)
139{ 128{
140 count = read_c0_count() - count; 129 expirelo = read_c0_count() + cycles_per_jiffy;
141 expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
142 write_c0_count(expirelo - cycles_per_jiffy);
143 write_c0_compare(expirelo); 130 write_c0_compare(expirelo);
144 write_c0_count(count);
145} 131}
146 132
147int (*mips_timer_state)(void); 133int (*mips_timer_state)(void);
148void (*mips_timer_ack)(void); 134void (*mips_timer_ack)(void);
149unsigned int (*mips_hpt_read)(void); 135unsigned int (*mips_hpt_read)(void);
150void (*mips_hpt_init)(unsigned int); 136void (*mips_hpt_init)(void) __initdata = null_hpt_init;
151 137unsigned int mips_hpt_mask = 0xffffffff;
152/*
153 * Gettimeoffset routines. These routines returns the time duration
154 * since last timer interrupt in usecs.
155 *
156 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
157 * Otherwise use calibrate_gettimeoffset()
158 *
159 * If the CPU does not have the counter register, you can either supply
160 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
161 * gives the same resolution as HZ.
162 */
163
164static unsigned long null_gettimeoffset(void)
165{
166 return 0;
167}
168
169
170/* The function pointer to one of the gettimeoffset funcs. */
171unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
172
173
174static unsigned long fixed_rate_gettimeoffset(void)
175{
176 u32 count;
177 unsigned long res;
178
179 /* Get last timer tick in absolute kernel time */
180 count = mips_hpt_read();
181
182 /* .. relative to previous jiffy (32 bits is enough) */
183 count -= timerlo;
184
185 __asm__("multu %1,%2"
186 : "=h" (res)
187 : "r" (count), "r" (sll32_usecs_per_cycle)
188 : "lo", GCC_REG_ACCUM);
189
190 /*
191 * Due to possible jiffies inconsistencies, we need to check
192 * the result so that we'll get a timer that is monotonic.
193 */
194 if (res >= USECS_PER_JIFFY)
195 res = USECS_PER_JIFFY - 1;
196
197 return res;
198}
199
200
201/*
202 * Cached "1/(clocks per usec) * 2^32" value.
203 * It has to be recalculated once each jiffy.
204 */
205static unsigned long cached_quotient;
206
207/* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
208static unsigned long last_jiffies;
209
210/*
211 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
212 */
213static unsigned long calibrate_div32_gettimeoffset(void)
214{
215 u32 count;
216 unsigned long res, tmp;
217 unsigned long quotient;
218
219 tmp = jiffies;
220
221 quotient = cached_quotient;
222
223 if (last_jiffies != tmp) {
224 last_jiffies = tmp;
225 if (last_jiffies != 0) {
226 unsigned long r0;
227 do_div64_32(r0, timerhi, timerlo, tmp);
228 do_div64_32(quotient, USECS_PER_JIFFY,
229 USECS_PER_JIFFY_FRAC, r0);
230 cached_quotient = quotient;
231 }
232 }
233
234 /* Get last timer tick in absolute kernel time */
235 count = mips_hpt_read();
236
237 /* .. relative to previous jiffy (32 bits is enough) */
238 count -= timerlo;
239
240 __asm__("multu %1,%2"
241 : "=h" (res)
242 : "r" (count), "r" (quotient)
243 : "lo", GCC_REG_ACCUM);
244
245 /*
246 * Due to possible jiffies inconsistencies, we need to check
247 * the result so that we'll get a timer that is monotonic.
248 */
249 if (res >= USECS_PER_JIFFY)
250 res = USECS_PER_JIFFY - 1;
251
252 return res;
253}
254
255static unsigned long calibrate_div64_gettimeoffset(void)
256{
257 u32 count;
258 unsigned long res, tmp;
259 unsigned long quotient;
260
261 tmp = jiffies;
262
263 quotient = cached_quotient;
264
265 if (last_jiffies != tmp) {
266 last_jiffies = tmp;
267 if (last_jiffies) {
268 unsigned long r0;
269 __asm__(".set push\n\t"
270 ".set mips3\n\t"
271 "lwu %0,%3\n\t"
272 "dsll32 %1,%2,0\n\t"
273 "or %1,%1,%0\n\t"
274 "ddivu $0,%1,%4\n\t"
275 "mflo %1\n\t"
276 "dsll32 %0,%5,0\n\t"
277 "or %0,%0,%6\n\t"
278 "ddivu $0,%0,%1\n\t"
279 "mflo %0\n\t"
280 ".set pop"
281 : "=&r" (quotient), "=&r" (r0)
282 : "r" (timerhi), "m" (timerlo),
283 "r" (tmp), "r" (USECS_PER_JIFFY),
284 "r" (USECS_PER_JIFFY_FRAC)
285 : "hi", "lo", GCC_REG_ACCUM);
286 cached_quotient = quotient;
287 }
288 }
289
290 /* Get last timer tick in absolute kernel time */
291 count = mips_hpt_read();
292
293 /* .. relative to previous jiffy (32 bits is enough) */
294 count -= timerlo;
295
296 __asm__("multu %1,%2"
297 : "=h" (res)
298 : "r" (count), "r" (quotient)
299 : "lo", GCC_REG_ACCUM);
300
301 /*
302 * Due to possible jiffies inconsistencies, we need to check
303 * the result so that we'll get a timer that is monotonic.
304 */
305 if (res >= USECS_PER_JIFFY)
306 res = USECS_PER_JIFFY - 1;
307
308 return res;
309}
310
311 138
312/* last time when xtime and rtc are sync'ed up */ 139/* last time when xtime and rtc are sync'ed up */
313static long last_rtc_update; 140static long last_rtc_update;
@@ -334,18 +161,10 @@ void local_timer_interrupt(int irq, void *dev_id)
334 */ 161 */
335irqreturn_t timer_interrupt(int irq, void *dev_id) 162irqreturn_t timer_interrupt(int irq, void *dev_id)
336{ 163{
337 unsigned long j;
338 unsigned int count;
339
340 write_seqlock(&xtime_lock); 164 write_seqlock(&xtime_lock);
341 165
342 count = mips_hpt_read();
343 mips_timer_ack(); 166 mips_timer_ack();
344 167
345 /* Update timerhi/timerlo for intra-jiffy calibration. */
346 timerhi += count < timerlo; /* Wrap around */
347 timerlo = count;
348
349 /* 168 /*
350 * call the generic timer interrupt handling 169 * call the generic timer interrupt handling
351 */ 170 */
@@ -368,47 +187,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
368 } 187 }
369 } 188 }
370 189
371 /*
372 * If jiffies has overflown in this timer_interrupt, we must
373 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
374 * quotient calc still valid. -arca
375 *
376 * The first timer interrupt comes late as interrupts are
377 * enabled long after timers are initialized. Therefore the
378 * high precision timer is fast, leading to wrong gettimeoffset()
379 * calculations. We deal with it by setting it based on the
380 * number of its ticks between the second and the third interrupt.
381 * That is still somewhat imprecise, but it's a good estimate.
382 * --macro
383 */
384 j = jiffies;
385 if (j < 4) {
386 static unsigned int prev_count;
387 static int hpt_initialized;
388
389 switch (j) {
390 case 0:
391 timerhi = timerlo = 0;
392 mips_hpt_init(count);
393 break;
394 case 2:
395 prev_count = count;
396 break;
397 case 3:
398 if (!hpt_initialized) {
399 unsigned int c3 = 3 * (count - prev_count);
400
401 timerhi = 0;
402 timerlo = c3;
403 mips_hpt_init(count - c3);
404 hpt_initialized = 1;
405 }
406 break;
407 default:
408 break;
409 }
410 }
411
412 write_sequnlock(&xtime_lock); 190 write_sequnlock(&xtime_lock);
413 191
414 /* 192 /*
@@ -476,12 +254,11 @@ asmlinkage void ll_local_timer_interrupt(int irq)
476 * 1) board_time_init() - 254 * 1) board_time_init() -
477 * a) (optional) set up RTC routines, 255 * a) (optional) set up RTC routines,
478 * b) (optional) calibrate and set the mips_hpt_frequency 256 * b) (optional) calibrate and set the mips_hpt_frequency
479 * (only needed if you intended to use fixed_rate_gettimeoffset 257 * (only needed if you intended to use cpu counter as timer interrupt
480 * or use cpu counter as timer interrupt source) 258 * source)
481 * 2) setup xtime based on rtc_mips_get_time(). 259 * 2) setup xtime based on rtc_mips_get_time().
482 * 3) choose a appropriate gettimeoffset routine. 260 * 3) calculate a couple of cached variables for later usage
483 * 4) calculate a couple of cached variables for later usage 261 * 4) plat_timer_setup() -
484 * 5) plat_timer_setup() -
485 * a) (optional) over-write any choices made above by time_init(). 262 * a) (optional) over-write any choices made above by time_init().
486 * b) machine specific code should setup the timer irqaction. 263 * b) machine specific code should setup the timer irqaction.
487 * c) enable the timer interrupt 264 * c) enable the timer interrupt
@@ -533,13 +310,48 @@ static unsigned int __init calibrate_hpt(void)
533 } while (--i); 310 } while (--i);
534 hpt_end = mips_hpt_read(); 311 hpt_end = mips_hpt_read();
535 312
536 hpt_count = hpt_end - hpt_start; 313 hpt_count = (hpt_end - hpt_start) & mips_hpt_mask;
537 hz = HZ; 314 hz = HZ;
538 frequency = (u64)hpt_count * (u64)hz; 315 frequency = (u64)hpt_count * (u64)hz;
539 316
540 return frequency >> log_2_loops; 317 return frequency >> log_2_loops;
541} 318}
542 319
320static cycle_t read_mips_hpt(void)
321{
322 return (cycle_t)mips_hpt_read();
323}
324
325static struct clocksource clocksource_mips = {
326 .name = "MIPS",
327 .read = read_mips_hpt,
328 .is_continuous = 1,
329};
330
331static void __init init_mips_clocksource(void)
332{
333 u64 temp;
334 u32 shift;
335
336 if (!mips_hpt_frequency || mips_hpt_read == null_hpt_read)
337 return;
338
339 /* Calclate a somewhat reasonable rating value */
340 clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
341 /* Find a shift value */
342 for (shift = 32; shift > 0; shift--) {
343 temp = (u64) NSEC_PER_SEC << shift;
344 do_div(temp, mips_hpt_frequency);
345 if ((temp >> 32) == 0)
346 break;
347 }
348 clocksource_mips.shift = shift;
349 clocksource_mips.mult = (u32)temp;
350 clocksource_mips.mask = mips_hpt_mask;
351
352 clocksource_register(&clocksource_mips);
353}
354
543void __init time_init(void) 355void __init time_init(void)
544{ 356{
545 if (board_time_init) 357 if (board_time_init)
@@ -555,41 +367,21 @@ void __init time_init(void)
555 -xtime.tv_sec, -xtime.tv_nsec); 367 -xtime.tv_sec, -xtime.tv_nsec);
556 368
557 /* Choose appropriate high precision timer routines. */ 369 /* Choose appropriate high precision timer routines. */
558 if (!cpu_has_counter && !mips_hpt_read) { 370 if (!cpu_has_counter && !mips_hpt_read)
559 /* No high precision timer -- sorry. */ 371 /* No high precision timer -- sorry. */
560 mips_hpt_read = null_hpt_read; 372 mips_hpt_read = null_hpt_read;
561 mips_hpt_init = null_hpt_init; 373 else if (!mips_hpt_frequency && !mips_timer_state) {
562 } else if (!mips_hpt_frequency && !mips_timer_state) {
563 /* A high precision timer of unknown frequency. */ 374 /* A high precision timer of unknown frequency. */
564 if (!mips_hpt_read) { 375 if (!mips_hpt_read)
565 /* No external high precision timer -- use R4k. */ 376 /* No external high precision timer -- use R4k. */
566 mips_hpt_read = c0_hpt_read; 377 mips_hpt_read = c0_hpt_read;
567 mips_hpt_init = c0_hpt_init;
568 }
569
570 if (cpu_has_mips32r1 || cpu_has_mips32r2 ||
571 (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
572 (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
573 /*
574 * We need to calibrate the counter but we don't have
575 * 64-bit division.
576 */
577 do_gettimeoffset = calibrate_div32_gettimeoffset;
578 else
579 /*
580 * We need to calibrate the counter but we *do* have
581 * 64-bit division.
582 */
583 do_gettimeoffset = calibrate_div64_gettimeoffset;
584 } else { 378 } else {
585 /* We know counter frequency. Or we can get it. */ 379 /* We know counter frequency. Or we can get it. */
586 if (!mips_hpt_read) { 380 if (!mips_hpt_read) {
587 /* No external high precision timer -- use R4k. */ 381 /* No external high precision timer -- use R4k. */
588 mips_hpt_read = c0_hpt_read; 382 mips_hpt_read = c0_hpt_read;
589 383
590 if (mips_timer_state) 384 if (!mips_timer_state) {
591 mips_hpt_init = c0_hpt_init;
592 else {
593 /* No external timer interrupt -- use R4k. */ 385 /* No external timer interrupt -- use R4k. */
594 mips_hpt_init = c0_hpt_timer_init; 386 mips_hpt_init = c0_hpt_timer_init;
595 mips_timer_ack = c0_timer_ack; 387 mips_timer_ack = c0_timer_ack;
@@ -598,16 +390,9 @@ void __init time_init(void)
598 if (!mips_hpt_frequency) 390 if (!mips_hpt_frequency)
599 mips_hpt_frequency = calibrate_hpt(); 391 mips_hpt_frequency = calibrate_hpt();
600 392
601 do_gettimeoffset = fixed_rate_gettimeoffset;
602
603 /* Calculate cache parameters. */ 393 /* Calculate cache parameters. */
604 cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ; 394 cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
605 395
606 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
607 do_div64_32(sll32_usecs_per_cycle,
608 1000000, mips_hpt_frequency / 2,
609 mips_hpt_frequency);
610
611 /* Report the high precision timer rate for a reference. */ 396 /* Report the high precision timer rate for a reference. */
612 printk("Using %u.%03u MHz high precision timer.\n", 397 printk("Using %u.%03u MHz high precision timer.\n",
613 ((mips_hpt_frequency + 500) / 1000) / 1000, 398 ((mips_hpt_frequency + 500) / 1000) / 1000,
@@ -619,7 +404,7 @@ void __init time_init(void)
619 mips_timer_ack = null_timer_ack; 404 mips_timer_ack = null_timer_ack;
620 405
621 /* This sets up the high precision timer for the first interrupt. */ 406 /* This sets up the high precision timer for the first interrupt. */
622 mips_hpt_init(mips_hpt_read()); 407 mips_hpt_init();
623 408
624 /* 409 /*
625 * Call board specific timer interrupt setup. 410 * Call board specific timer interrupt setup.
@@ -633,6 +418,8 @@ void __init time_init(void)
633 * is not invoked accidentally. 418 * is not invoked accidentally.
634 */ 419 */
635 plat_timer_setup(&timer_irqaction); 420 plat_timer_setup(&timer_irqaction);
421
422 init_mips_clocksource();
636} 423}
637 424
638#define FEBRUARY 2 425#define FEBRUARY 2