1 #include <linux/clocksource.h>
2 #include <linux/clockchips.h>
3 #include <linux/delay.h>
4 #include <linux/errno.h>
5 #include <linux/hpet.h>
6 #include <linux/init.h>
7 #include <linux/sysdev.h>
9 #include <linux/delay.h>
11 #include <asm/fixmap.h>
13 #include <asm/i8253.h>
16 #define HPET_MASK CLOCKSOURCE_MASK(32)
19 /* FSEC = 10^-15 NSEC = 10^-9 */
20 #define FSEC_PER_NSEC 1000000
23 * HPET address is set in acpi/boot.c, when an ACPI entry exists
25 unsigned long hpet_address;
26 static void __iomem *hpet_virt_address;
28 unsigned long hpet_readl(unsigned long a)
30 return readl(hpet_virt_address + a);
33 static inline void hpet_writel(unsigned long d, unsigned long a)
35 writel(d, hpet_virt_address + a);
40 #include <asm/pgtable.h>
42 static inline void hpet_set_mapping(void)
44 set_fixmap_nocache(FIX_HPET_BASE, hpet_address);
45 __set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);
46 hpet_virt_address = (void __iomem *)fix_to_virt(FIX_HPET_BASE);
49 static inline void hpet_clear_mapping(void)
51 hpet_virt_address = NULL;
56 static inline void hpet_set_mapping(void)
58 hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
61 static inline void hpet_clear_mapping(void)
63 iounmap(hpet_virt_address);
64 hpet_virt_address = NULL;
69 * HPET command line enable / disable
71 static int boot_hpet_disable;
73 static int __init hpet_setup(char* str)
76 if (!strncmp("disable", str, 7))
77 boot_hpet_disable = 1;
81 __setup("hpet=", hpet_setup);
83 static int __init disable_hpet(char *str)
85 boot_hpet_disable = 1;
88 __setup("nohpet", disable_hpet);
90 static inline int is_hpet_capable(void)
92 return (!boot_hpet_disable && hpet_address);
96 * HPET timer interrupt enable / disable
98 static int hpet_legacy_int_enabled;
101 * is_hpet_enabled - check whether the hpet timer interrupt is enabled
103 int is_hpet_enabled(void)
105 return is_hpet_capable() && hpet_legacy_int_enabled;
109 * When the hpet driver (/dev/hpet) is enabled, we need to reserve
110 * timer 0 and timer 1 in case of RTC emulation.
113 static void hpet_reserve_platform_timers(unsigned long id)
115 struct hpet __iomem *hpet = hpet_virt_address;
116 struct hpet_timer __iomem *timer = &hpet->hpet_timers[2];
117 unsigned int nrtimers, i;
120 nrtimers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
122 memset(&hd, 0, sizeof (hd));
123 hd.hd_phys_address = hpet_address;
124 hd.hd_address = hpet;
125 hd.hd_nirqs = nrtimers;
126 hd.hd_flags = HPET_DATA_PLATFORM;
127 hpet_reserve_timer(&hd, 0);
129 #ifdef CONFIG_HPET_EMULATE_RTC
130 hpet_reserve_timer(&hd, 1);
133 hd.hd_irq[0] = HPET_LEGACY_8254;
134 hd.hd_irq[1] = HPET_LEGACY_RTC;
136 for (i = 2; i < nrtimers; timer++, i++)
137 hd.hd_irq[i] = (timer->hpet_config & Tn_INT_ROUTE_CNF_MASK) >>
138 Tn_INT_ROUTE_CNF_SHIFT;
144 static void hpet_reserve_platform_timers(unsigned long id) { }
150 static unsigned long hpet_period;
152 static void hpet_legacy_set_mode(enum clock_event_mode mode,
153 struct clock_event_device *evt);
154 static int hpet_legacy_next_event(unsigned long delta,
155 struct clock_event_device *evt);
158 * The hpet clock event device
160 static struct clock_event_device hpet_clockevent = {
162 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
163 .set_mode = hpet_legacy_set_mode,
164 .set_next_event = hpet_legacy_next_event,
169 static void hpet_start_counter(void)
171 unsigned long cfg = hpet_readl(HPET_CFG);
173 cfg &= ~HPET_CFG_ENABLE;
174 hpet_writel(cfg, HPET_CFG);
175 hpet_writel(0, HPET_COUNTER);
176 hpet_writel(0, HPET_COUNTER + 4);
177 cfg |= HPET_CFG_ENABLE;
178 hpet_writel(cfg, HPET_CFG);
181 static void hpet_enable_legacy_int(void)
183 unsigned long cfg = hpet_readl(HPET_CFG);
185 cfg |= HPET_CFG_LEGACY;
186 hpet_writel(cfg, HPET_CFG);
187 hpet_legacy_int_enabled = 1;
190 static void hpet_legacy_clockevent_register(void)
194 /* Start HPET legacy interrupts */
195 hpet_enable_legacy_int();
198 * The period is a femto seconds value. We need to calculate the
199 * scaled math multiplication factor for nanosecond to hpet tick
202 hpet_freq = 1000000000000000ULL;
203 do_div(hpet_freq, hpet_period);
204 hpet_clockevent.mult = div_sc((unsigned long) hpet_freq,
206 /* Calculate the min / max delta */
207 hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
209 hpet_clockevent.min_delta_ns = clockevent_delta2ns(0x30,
213 * Start hpet with the boot cpu mask and make it
214 * global after the IO_APIC has been initialized.
216 hpet_clockevent.cpumask = cpumask_of_cpu(smp_processor_id());
217 clockevents_register_device(&hpet_clockevent);
218 global_clock_event = &hpet_clockevent;
219 printk(KERN_DEBUG "hpet clockevent registered\n");
222 static void hpet_legacy_set_mode(enum clock_event_mode mode,
223 struct clock_event_device *evt)
225 unsigned long cfg, cmp, now;
229 case CLOCK_EVT_MODE_PERIODIC:
230 delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * hpet_clockevent.mult;
231 delta >>= hpet_clockevent.shift;
232 now = hpet_readl(HPET_COUNTER);
233 cmp = now + (unsigned long) delta;
234 cfg = hpet_readl(HPET_T0_CFG);
235 cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
236 HPET_TN_SETVAL | HPET_TN_32BIT;
237 hpet_writel(cfg, HPET_T0_CFG);
239 * The first write after writing TN_SETVAL to the
240 * config register sets the counter value, the second
241 * write sets the period.
243 hpet_writel(cmp, HPET_T0_CMP);
245 hpet_writel((unsigned long) delta, HPET_T0_CMP);
248 case CLOCK_EVT_MODE_ONESHOT:
249 cfg = hpet_readl(HPET_T0_CFG);
250 cfg &= ~HPET_TN_PERIODIC;
251 cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
252 hpet_writel(cfg, HPET_T0_CFG);
255 case CLOCK_EVT_MODE_UNUSED:
256 case CLOCK_EVT_MODE_SHUTDOWN:
257 cfg = hpet_readl(HPET_T0_CFG);
258 cfg &= ~HPET_TN_ENABLE;
259 hpet_writel(cfg, HPET_T0_CFG);
262 case CLOCK_EVT_MODE_RESUME:
263 hpet_enable_legacy_int();
268 static int hpet_legacy_next_event(unsigned long delta,
269 struct clock_event_device *evt)
273 cnt = hpet_readl(HPET_COUNTER);
275 hpet_writel(cnt, HPET_T0_CMP);
277 return ((long)(hpet_readl(HPET_COUNTER) - cnt ) > 0) ? -ETIME : 0;
281 * Clock source related code
283 static cycle_t read_hpet(void)
285 return (cycle_t)hpet_readl(HPET_COUNTER);
289 static cycle_t __vsyscall_fn vread_hpet(void)
291 return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
295 static struct clocksource clocksource_hpet = {
301 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
302 .resume = hpet_start_counter,
308 static int hpet_clocksource_register(void)
313 /* Start the counter */
314 hpet_start_counter();
316 /* Verify whether hpet counter works */
321 * We don't know the TSC frequency yet, but waiting for
322 * 200000 TSC cycles is safe:
329 } while ((now - start) < 200000UL);
331 if (t1 == read_hpet()) {
333 "HPET counter not counting. HPET disabled\n");
337 /* Initialize and register HPET clocksource
339 * hpet period is in femto seconds per cycle
340 * so we need to convert this to ns/cyc units
341 * aproximated by mult/2^shift
343 * fsec/cyc * 1nsec/1000000fsec = nsec/cyc = mult/2^shift
344 * fsec/cyc * 1ns/1000000fsec * 2^shift = mult
345 * fsec/cyc * 2^shift * 1nsec/1000000fsec = mult
346 * (fsec/cyc << shift)/1000000 = mult
347 * (hpet_period << shift)/FSEC_PER_NSEC = mult
349 tmp = (u64)hpet_period << HPET_SHIFT;
350 do_div(tmp, FSEC_PER_NSEC);
351 clocksource_hpet.mult = (u32)tmp;
353 clocksource_register(&clocksource_hpet);
359 * Try to setup the HPET timer
361 int __init hpet_enable(void)
365 if (!is_hpet_capable())
371 * Read the period and check for a sane value:
373 hpet_period = hpet_readl(HPET_PERIOD);
374 if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
378 * Read the HPET ID register to retrieve the IRQ routing
379 * information and the number of channels
381 id = hpet_readl(HPET_ID);
383 #ifdef CONFIG_HPET_EMULATE_RTC
385 * The legacy routing mode needs at least two channels, tick timer
386 * and the rtc emulation channel.
388 if (!(id & HPET_ID_NUMBER))
392 if (hpet_clocksource_register())
395 if (id & HPET_ID_LEGSUP) {
396 hpet_legacy_clockevent_register();
402 hpet_clear_mapping();
403 boot_hpet_disable = 1;
408 * Needs to be late, as the reserve_timer code calls kalloc !
410 * Not a problem on i386 as hpet_enable is called from late_time_init,
411 * but on x86_64 it is necessary !
413 static __init int hpet_late_init(void)
415 if (!is_hpet_capable())
418 hpet_reserve_platform_timers(hpet_readl(HPET_ID));
421 fs_initcall(hpet_late_init);
423 #ifdef CONFIG_HPET_EMULATE_RTC
425 /* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
426 * is enabled, we support RTC interrupt functionality in software.
427 * RTC has 3 kinds of interrupts:
428 * 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
430 * 2) Alarm Interrupt - generate an interrupt at a specific time of day
431 * 3) Periodic Interrupt - generate periodic interrupt, with frequencies
432 * 2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
433 * (1) and (2) above are implemented using polling at a frequency of
434 * 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
435 * overhead. (DEFAULT_RTC_INT_FREQ)
436 * For (3), we use interrupts at 64Hz or user specified periodic
437 * frequency, whichever is higher.
439 #include <linux/mc146818rtc.h>
440 #include <linux/rtc.h>
442 #define DEFAULT_RTC_INT_FREQ 64
443 #define DEFAULT_RTC_SHIFT 6
444 #define RTC_NUM_INTS 1
446 static unsigned long hpet_rtc_flags;
447 static unsigned long hpet_prev_update_sec;
448 static struct rtc_time hpet_alarm_time;
449 static unsigned long hpet_pie_count;
450 static unsigned long hpet_t1_cmp;
451 static unsigned long hpet_default_delta;
452 static unsigned long hpet_pie_delta;
453 static unsigned long hpet_pie_limit;
456 * Timer 1 for RTC emulation. We use one shot mode, as periodic mode
457 * is not supported by all HPET implementations for timer 1.
459 * hpet_rtc_timer_init() is called when the rtc is initialized.
461 int hpet_rtc_timer_init(void)
463 unsigned long cfg, cnt, delta, flags;
465 if (!is_hpet_enabled())
468 if (!hpet_default_delta) {
471 clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
472 clc >>= hpet_clockevent.shift + DEFAULT_RTC_SHIFT;
473 hpet_default_delta = (unsigned long) clc;
476 if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
477 delta = hpet_default_delta;
479 delta = hpet_pie_delta;
481 local_irq_save(flags);
483 cnt = delta + hpet_readl(HPET_COUNTER);
484 hpet_writel(cnt, HPET_T1_CMP);
487 cfg = hpet_readl(HPET_T1_CFG);
488 cfg &= ~HPET_TN_PERIODIC;
489 cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
490 hpet_writel(cfg, HPET_T1_CFG);
492 local_irq_restore(flags);
498 * The functions below are called from rtc driver.
499 * Return 0 if HPET is not being used.
500 * Otherwise do the necessary changes and return 1.
502 int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
504 if (!is_hpet_enabled())
507 hpet_rtc_flags &= ~bit_mask;
511 int hpet_set_rtc_irq_bit(unsigned long bit_mask)
513 unsigned long oldbits = hpet_rtc_flags;
515 if (!is_hpet_enabled())
518 hpet_rtc_flags |= bit_mask;
521 hpet_rtc_timer_init();
526 int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
529 if (!is_hpet_enabled())
532 hpet_alarm_time.tm_hour = hrs;
533 hpet_alarm_time.tm_min = min;
534 hpet_alarm_time.tm_sec = sec;
539 int hpet_set_periodic_freq(unsigned long freq)
543 if (!is_hpet_enabled())
546 if (freq <= DEFAULT_RTC_INT_FREQ)
547 hpet_pie_limit = DEFAULT_RTC_INT_FREQ / freq;
549 clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
551 clc >>= hpet_clockevent.shift;
552 hpet_pie_delta = (unsigned long) clc;
557 int hpet_rtc_dropped_irq(void)
559 return is_hpet_enabled();
562 static void hpet_rtc_timer_reinit(void)
564 unsigned long cfg, delta;
567 if (unlikely(!hpet_rtc_flags)) {
568 cfg = hpet_readl(HPET_T1_CFG);
569 cfg &= ~HPET_TN_ENABLE;
570 hpet_writel(cfg, HPET_T1_CFG);
574 if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
575 delta = hpet_default_delta;
577 delta = hpet_pie_delta;
580 * Increment the comparator value until we are ahead of the
584 hpet_t1_cmp += delta;
585 hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
587 } while ((long)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0);
590 if (hpet_rtc_flags & RTC_PIE)
591 hpet_pie_count += lost_ints;
592 if (printk_ratelimit())
593 printk(KERN_WARNING "rtc: lost %d interrupts\n",
598 irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
600 struct rtc_time curr_time;
601 unsigned long rtc_int_flag = 0;
603 hpet_rtc_timer_reinit();
605 if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
606 rtc_get_rtc_time(&curr_time);
608 if (hpet_rtc_flags & RTC_UIE &&
609 curr_time.tm_sec != hpet_prev_update_sec) {
610 rtc_int_flag = RTC_UF;
611 hpet_prev_update_sec = curr_time.tm_sec;
614 if (hpet_rtc_flags & RTC_PIE &&
615 ++hpet_pie_count >= hpet_pie_limit) {
616 rtc_int_flag |= RTC_PF;
620 if (hpet_rtc_flags & RTC_PIE &&
621 (curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
622 (curr_time.tm_min == hpet_alarm_time.tm_min) &&
623 (curr_time.tm_hour == hpet_alarm_time.tm_hour))
624 rtc_int_flag |= RTC_AF;
627 rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
628 rtc_interrupt(rtc_int_flag, dev_id);