2 * Timer device implementation for SGI SN platforms.
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
8 * Copyright (c) 2001-2006 Silicon Graphics, Inc. All rights reserved.
10 * This driver exports an API that should be supportable by any HPET or IA-PC
11 * multimedia timer. The code below is currently specific to the SGI Altix
14 * 11/01/01 - jbarnes - initial revision
15 * 9/10/04 - Christoph Lameter - remove interrupt support for kernel inclusion
16 * 10/1/04 - Christoph Lameter - provide posix clock CLOCK_SGI_CYCLE
17 * 10/13/04 - Christoph Lameter, Dimitri Sivanich - provide timer interrupt
18 * support via the posix timer interface
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/ioctl.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/errno.h>
29 #include <linux/mmtimer.h>
30 #include <linux/miscdevice.h>
31 #include <linux/posix-timers.h>
32 #include <linux/interrupt.h>
33 #include <linux/time.h>
34 #include <linux/math64.h>
35 #include <linux/mutex.h>
36 #include <linux/slab.h>
38 #include <asm/uaccess.h>
39 #include <asm/sn/addrs.h>
40 #include <asm/sn/intr.h>
41 #include <asm/sn/shub_mmr.h>
42 #include <asm/sn/nodepda.h>
43 #include <asm/sn/shubio.h>
45 MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
46 MODULE_DESCRIPTION("SGI Altix RTC Timer");
47 MODULE_LICENSE("GPL");
49 /* name of the device, usually in /dev */
50 #define MMTIMER_NAME "mmtimer"
51 #define MMTIMER_DESC "SGI Altix RTC Timer"
52 #define MMTIMER_VERSION "2.1"
54 #define RTC_BITS 55 /* 55 bits for this implementation */
56 extern unsigned long sn_rtc_cycles_per_second;
58 #define RTC_COUNTER_ADDR ((long *)LOCAL_MMR_ADDR(SH_RTC))
60 #define rtc_time() (*RTC_COUNTER_ADDR)
62 static DEFINE_MUTEX(mmtimer_mutex);
63 static long mmtimer_ioctl(struct file *file, unsigned int cmd,
65 static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
68 * Period in femtoseconds (10^-15 s)
70 static unsigned long mmtimer_femtoperiod = 0;
72 static const struct file_operations mmtimer_fops = {
75 .unlocked_ioctl = mmtimer_ioctl,
76 .llseek = noop_llseek,
80 * We only have comparison registers RTC1-4 currently available per
81 * node. RTC0 is used by SAL.
83 /* Check for an RTC interrupt pending */
84 static int mmtimer_int_pending(int comparator)
86 if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
87 SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
93 /* Clear the RTC interrupt pending bit */
94 static void mmtimer_clr_int_pending(int comparator)
96 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
97 SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
100 /* Setup timer on comparator RTC1 */
101 static void mmtimer_setup_int_0(int cpu, u64 expires)
105 /* Disable interrupt */
106 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
108 /* Initialize comparator value */
109 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
111 /* Clear pending bit */
112 mmtimer_clr_int_pending(0);
114 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
115 ((u64)cpu_physical_id(cpu) <<
116 SH_RTC1_INT_CONFIG_PID_SHFT);
118 /* Set configuration */
119 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
121 /* Enable RTC interrupts */
122 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
124 /* Initialize comparator value */
125 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
130 /* Setup timer on comparator RTC2 */
131 static void mmtimer_setup_int_1(int cpu, u64 expires)
135 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
137 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
139 mmtimer_clr_int_pending(1);
141 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
142 ((u64)cpu_physical_id(cpu) <<
143 SH_RTC2_INT_CONFIG_PID_SHFT);
145 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
147 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
149 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
152 /* Setup timer on comparator RTC3 */
153 static void mmtimer_setup_int_2(int cpu, u64 expires)
157 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
159 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
161 mmtimer_clr_int_pending(2);
163 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
164 ((u64)cpu_physical_id(cpu) <<
165 SH_RTC3_INT_CONFIG_PID_SHFT);
167 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
169 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
171 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
175 * This function must be called with interrupts disabled and preemption off
176 * in order to insure that the setup succeeds in a deterministic time frame.
177 * It will check if the interrupt setup succeeded.
179 static int mmtimer_setup(int cpu, int comparator, unsigned long expires,
180 u64 *set_completion_time)
182 switch (comparator) {
184 mmtimer_setup_int_0(cpu, expires);
187 mmtimer_setup_int_1(cpu, expires);
190 mmtimer_setup_int_2(cpu, expires);
193 /* We might've missed our expiration time */
194 *set_completion_time = rtc_time();
195 if (*set_completion_time <= expires)
199 * If an interrupt is already pending then its okay
200 * if not then we failed
202 return mmtimer_int_pending(comparator);
205 static int mmtimer_disable_int(long nasid, int comparator)
207 switch (comparator) {
209 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
210 0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
213 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
214 0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
217 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
218 0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
226 #define COMPARATOR 1 /* The comparator to use */
228 #define TIMER_OFF 0xbadcabLL /* Timer is not setup */
229 #define TIMER_SET 0 /* Comparator is set for this timer */
231 #define MMTIMER_INTERVAL_RETRY_INCREMENT_DEFAULT 40
233 /* There is one of these for each timer */
236 struct k_itimer *timer;
240 struct mmtimer_node {
241 spinlock_t lock ____cacheline_aligned;
242 struct rb_root timer_head;
243 struct rb_node *next;
244 struct tasklet_struct tasklet;
246 static struct mmtimer_node *timers;
248 static unsigned mmtimer_interval_retry_increment =
249 MMTIMER_INTERVAL_RETRY_INCREMENT_DEFAULT;
250 module_param(mmtimer_interval_retry_increment, uint, 0644);
251 MODULE_PARM_DESC(mmtimer_interval_retry_increment,
252 "RTC ticks to add to expiration on interval retry (default 40)");
255 * Add a new mmtimer struct to the node's mmtimer list.
256 * This function assumes the struct mmtimer_node is locked.
258 static void mmtimer_add_list(struct mmtimer *n)
260 int nodeid = n->timer->it.mmtimer.node;
261 unsigned long expires = n->timer->it.mmtimer.expires;
262 struct rb_node **link = &timers[nodeid].timer_head.rb_node;
263 struct rb_node *parent = NULL;
267 * Find the right place in the rbtree:
271 x = rb_entry(parent, struct mmtimer, list);
273 if (expires < x->timer->it.mmtimer.expires)
274 link = &(*link)->rb_left;
276 link = &(*link)->rb_right;
280 * Insert the timer to the rbtree and check whether it
281 * replaces the first pending timer
283 rb_link_node(&n->list, parent, link);
284 rb_insert_color(&n->list, &timers[nodeid].timer_head);
286 if (!timers[nodeid].next || expires < rb_entry(timers[nodeid].next,
287 struct mmtimer, list)->timer->it.mmtimer.expires)
288 timers[nodeid].next = &n->list;
292 * Set the comparator for the next timer.
293 * This function assumes the struct mmtimer_node is locked.
295 static void mmtimer_set_next_timer(int nodeid)
297 struct mmtimer_node *n = &timers[nodeid];
300 u64 expires, exp, set_completion_time;
307 x = rb_entry(n->next, struct mmtimer, list);
309 if (!t->it.mmtimer.incr) {
310 /* Not an interval timer */
311 if (!mmtimer_setup(x->cpu, COMPARATOR,
312 t->it.mmtimer.expires,
313 &set_completion_time)) {
314 /* Late setup, fire now */
315 tasklet_schedule(&n->tasklet);
322 expires = exp = t->it.mmtimer.expires;
323 while (!mmtimer_setup(x->cpu, COMPARATOR, expires,
324 &set_completion_time)) {
328 expires = set_completion_time +
329 mmtimer_interval_retry_increment + (1 << i);
330 /* Calculate overruns as we go. */
331 to = ((u64)(expires - exp) / t->it.mmtimer.incr);
334 t->it.mmtimer.expires += t->it.mmtimer.incr * to;
335 exp = t->it.mmtimer.expires;
338 printk(KERN_ALERT "mmtimer: cannot reschedule timer\n");
339 t->it.mmtimer.clock = TIMER_OFF;
340 n->next = rb_next(&x->list);
341 rb_erase(&x->list, &n->timer_head);
349 * mmtimer_ioctl - ioctl interface for /dev/mmtimer
350 * @file: file structure for the device
351 * @cmd: command to execute
352 * @arg: optional argument to command
354 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
359 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
360 * of the page where the registers are mapped) for the counter in question.
362 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
365 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
368 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
370 * %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
372 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
373 * in the address specified by @arg.
375 static long mmtimer_ioctl(struct file *file, unsigned int cmd,
380 mutex_lock(&mmtimer_mutex);
383 case MMTIMER_GETOFFSET: /* offset of the counter */
385 * SN RTC registers are on their own 64k page
387 if(PAGE_SIZE <= (1 << 16))
388 ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
393 case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
394 if(copy_to_user((unsigned long __user *)arg,
395 &mmtimer_femtoperiod, sizeof(unsigned long)))
399 case MMTIMER_GETFREQ: /* frequency in Hz */
400 if(copy_to_user((unsigned long __user *)arg,
401 &sn_rtc_cycles_per_second,
402 sizeof(unsigned long)))
406 case MMTIMER_GETBITS: /* number of bits in the clock */
410 case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
411 ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
414 case MMTIMER_GETCOUNTER:
415 if(copy_to_user((unsigned long __user *)arg,
416 RTC_COUNTER_ADDR, sizeof(unsigned long)))
423 mutex_unlock(&mmtimer_mutex);
428 * mmtimer_mmap - maps the clock's registers into userspace
429 * @file: file structure for the device
430 * @vma: VMA to map the registers into
432 * Calls remap_pfn_range() to map the clock's registers into
433 * the calling process' address space.
435 static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
437 unsigned long mmtimer_addr;
439 if (vma->vm_end - vma->vm_start != PAGE_SIZE)
442 if (vma->vm_flags & VM_WRITE)
445 if (PAGE_SIZE > (1 << 16))
448 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
450 mmtimer_addr = __pa(RTC_COUNTER_ADDR);
451 mmtimer_addr &= ~(PAGE_SIZE - 1);
452 mmtimer_addr &= 0xfffffffffffffffUL;
454 if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
455 PAGE_SIZE, vma->vm_page_prot)) {
456 printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
463 static struct miscdevice mmtimer_miscdev = {
469 static struct timespec sgi_clock_offset;
470 static int sgi_clock_period;
473 * Posix Timer Interface
476 static struct timespec sgi_clock_offset;
477 static int sgi_clock_period;
479 static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
483 nsec = rtc_time() * sgi_clock_period
484 + sgi_clock_offset.tv_nsec;
485 *tp = ns_to_timespec(nsec);
486 tp->tv_sec += sgi_clock_offset.tv_sec;
490 static int sgi_clock_set(clockid_t clockid, struct timespec *tp)
496 nsec = rtc_time() * sgi_clock_period;
498 sgi_clock_offset.tv_sec = tp->tv_sec - div_u64_rem(nsec, NSEC_PER_SEC, &rem);
500 if (rem <= tp->tv_nsec)
501 sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
503 sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
504 sgi_clock_offset.tv_sec--;
510 * mmtimer_interrupt - timer interrupt handler
512 * @dev_id: device the irq came from
514 * Called when one of the comarators matches the counter, This
515 * routine will send signals to processes that have requested
518 * This interrupt is run in an interrupt context
519 * by the SHUB. It is therefore safe to locally access SHub
523 mmtimer_interrupt(int irq, void *dev_id)
525 unsigned long expires = 0;
526 int result = IRQ_NONE;
527 unsigned indx = cpu_to_node(smp_processor_id());
528 struct mmtimer *base;
530 spin_lock(&timers[indx].lock);
531 base = rb_entry(timers[indx].next, struct mmtimer, list);
533 spin_unlock(&timers[indx].lock);
537 if (base->cpu == smp_processor_id()) {
539 expires = base->timer->it.mmtimer.expires;
540 /* expires test won't work with shared irqs */
541 if ((mmtimer_int_pending(COMPARATOR) > 0) ||
542 (expires && (expires <= rtc_time()))) {
543 mmtimer_clr_int_pending(COMPARATOR);
544 tasklet_schedule(&timers[indx].tasklet);
545 result = IRQ_HANDLED;
548 spin_unlock(&timers[indx].lock);
552 static void mmtimer_tasklet(unsigned long data)
555 struct mmtimer_node *mn = &timers[nodeid];
560 /* Send signal and deal with periodic signals */
561 spin_lock_irqsave(&mn->lock, flags);
565 x = rb_entry(mn->next, struct mmtimer, list);
568 if (t->it.mmtimer.clock == TIMER_OFF)
573 mn->next = rb_next(&x->list);
574 rb_erase(&x->list, &mn->timer_head);
576 if (posix_timer_event(t, 0) != 0)
579 if(t->it.mmtimer.incr) {
580 t->it.mmtimer.expires += t->it.mmtimer.incr;
583 /* Ensure we don't false trigger in mmtimer_interrupt */
584 t->it.mmtimer.clock = TIMER_OFF;
585 t->it.mmtimer.expires = 0;
588 /* Set comparator for next timer, if there is one */
589 mmtimer_set_next_timer(nodeid);
591 t->it_overrun_last = t->it_overrun;
593 spin_unlock_irqrestore(&mn->lock, flags);
596 static int sgi_timer_create(struct k_itimer *timer)
598 /* Insure that a newly created timer is off */
599 timer->it.mmtimer.clock = TIMER_OFF;
603 /* This does not really delete a timer. It just insures
604 * that the timer is not active
606 * Assumption: it_lock is already held with irq's disabled
608 static int sgi_timer_del(struct k_itimer *timr)
610 cnodeid_t nodeid = timr->it.mmtimer.node;
611 unsigned long irqflags;
613 spin_lock_irqsave(&timers[nodeid].lock, irqflags);
614 if (timr->it.mmtimer.clock != TIMER_OFF) {
615 unsigned long expires = timr->it.mmtimer.expires;
616 struct rb_node *n = timers[nodeid].timer_head.rb_node;
617 struct mmtimer *uninitialized_var(t);
620 timr->it.mmtimer.clock = TIMER_OFF;
621 timr->it.mmtimer.expires = 0;
624 t = rb_entry(n, struct mmtimer, list);
625 if (t->timer == timr)
628 if (expires < t->timer->it.mmtimer.expires)
635 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
639 if (timers[nodeid].next == n) {
640 timers[nodeid].next = rb_next(n);
644 rb_erase(n, &timers[nodeid].timer_head);
648 mmtimer_disable_int(cnodeid_to_nasid(nodeid),
650 mmtimer_set_next_timer(nodeid);
653 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
657 /* Assumption: it_lock is already held with irq's disabled */
658 static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
661 if (timr->it.mmtimer.clock == TIMER_OFF) {
662 cur_setting->it_interval.tv_nsec = 0;
663 cur_setting->it_interval.tv_sec = 0;
664 cur_setting->it_value.tv_nsec = 0;
665 cur_setting->it_value.tv_sec =0;
669 cur_setting->it_interval = ns_to_timespec(timr->it.mmtimer.incr * sgi_clock_period);
670 cur_setting->it_value = ns_to_timespec((timr->it.mmtimer.expires - rtc_time()) * sgi_clock_period);
674 static int sgi_timer_set(struct k_itimer *timr, int flags,
675 struct itimerspec * new_setting,
676 struct itimerspec * old_setting)
678 unsigned long when, period, irqflags;
681 struct mmtimer *base;
685 sgi_timer_get(timr, old_setting);
688 when = timespec_to_ns(&new_setting->it_value);
689 period = timespec_to_ns(&new_setting->it_interval);
695 base = kmalloc(sizeof(struct mmtimer), GFP_KERNEL);
699 if (flags & TIMER_ABSTIME) {
704 now = timespec_to_ns(&n);
708 /* Fire the timer immediately */
713 * Convert to sgi clock period. Need to keep rtc_time() as near as possible
714 * to getnstimeofday() in order to be as faithful as possible to the time
717 when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
718 period = (period + sgi_clock_period - 1) / sgi_clock_period;
721 * We are allocating a local SHub comparator. If we would be moved to another
722 * cpu then another SHub may be local to us. Prohibit that by switching off
727 nodeid = cpu_to_node(smp_processor_id());
729 /* Lock the node timer structure */
730 spin_lock_irqsave(&timers[nodeid].lock, irqflags);
733 base->cpu = smp_processor_id();
735 timr->it.mmtimer.clock = TIMER_SET;
736 timr->it.mmtimer.node = nodeid;
737 timr->it.mmtimer.incr = period;
738 timr->it.mmtimer.expires = when;
740 n = timers[nodeid].next;
742 /* Add the new struct mmtimer to node's timer list */
743 mmtimer_add_list(base);
745 if (timers[nodeid].next == n) {
746 /* No need to reprogram comparator for now */
747 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
752 /* We need to reprogram the comparator */
754 mmtimer_disable_int(cnodeid_to_nasid(nodeid), COMPARATOR);
756 mmtimer_set_next_timer(nodeid);
758 /* Unlock the node timer structure */
759 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
766 static struct k_clock sgi_clock = {
768 .clock_set = sgi_clock_set,
769 .clock_get = sgi_clock_get,
770 .timer_create = sgi_timer_create,
771 .nsleep = do_posix_clock_nonanosleep,
772 .timer_set = sgi_timer_set,
773 .timer_del = sgi_timer_del,
774 .timer_get = sgi_timer_get
778 * mmtimer_init - device initialization routine
780 * Does initial setup for the mmtimer device.
782 static int __init mmtimer_init(void)
784 cnodeid_t node, maxn = -1;
786 if (!ia64_platform_is("sn2"))
790 * Sanity check the cycles/sec variable
792 if (sn_rtc_cycles_per_second < 100000) {
793 printk(KERN_ERR "%s: unable to determine clock frequency\n",
798 mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
799 2) / sn_rtc_cycles_per_second;
801 if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, IRQF_PERCPU, MMTIMER_NAME, NULL)) {
802 printk(KERN_WARNING "%s: unable to allocate interrupt.",
807 if (misc_register(&mmtimer_miscdev)) {
808 printk(KERN_ERR "%s: failed to register device\n",
813 /* Get max numbered node, calculate slots needed */
814 for_each_online_node(node) {
819 /* Allocate list of node ptrs to mmtimer_t's */
820 timers = kzalloc(sizeof(struct mmtimer_node)*maxn, GFP_KERNEL);
821 if (timers == NULL) {
822 printk(KERN_ERR "%s: failed to allocate memory for device\n",
827 /* Initialize struct mmtimer's for each online node */
828 for_each_online_node(node) {
829 spin_lock_init(&timers[node].lock);
830 tasklet_init(&timers[node].tasklet, mmtimer_tasklet,
831 (unsigned long) node);
834 sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
835 register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);
837 printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
838 sn_rtc_cycles_per_second/(unsigned long)1E6);
844 misc_deregister(&mmtimer_miscdev);
846 free_irq(SGI_MMTIMER_VECTOR, NULL);
851 module_init(mmtimer_init);