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,
79 * We only have comparison registers RTC1-4 currently available per
80 * node. RTC0 is used by SAL.
82 /* Check for an RTC interrupt pending */
83 static int mmtimer_int_pending(int comparator)
85 if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
86 SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
92 /* Clear the RTC interrupt pending bit */
93 static void mmtimer_clr_int_pending(int comparator)
95 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
96 SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
99 /* Setup timer on comparator RTC1 */
100 static void mmtimer_setup_int_0(int cpu, u64 expires)
104 /* Disable interrupt */
105 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
107 /* Initialize comparator value */
108 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
110 /* Clear pending bit */
111 mmtimer_clr_int_pending(0);
113 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
114 ((u64)cpu_physical_id(cpu) <<
115 SH_RTC1_INT_CONFIG_PID_SHFT);
117 /* Set configuration */
118 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
120 /* Enable RTC interrupts */
121 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
123 /* Initialize comparator value */
124 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
129 /* Setup timer on comparator RTC2 */
130 static void mmtimer_setup_int_1(int cpu, u64 expires)
134 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
136 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
138 mmtimer_clr_int_pending(1);
140 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
141 ((u64)cpu_physical_id(cpu) <<
142 SH_RTC2_INT_CONFIG_PID_SHFT);
144 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
146 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
148 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
151 /* Setup timer on comparator RTC3 */
152 static void mmtimer_setup_int_2(int cpu, u64 expires)
156 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
158 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
160 mmtimer_clr_int_pending(2);
162 val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
163 ((u64)cpu_physical_id(cpu) <<
164 SH_RTC3_INT_CONFIG_PID_SHFT);
166 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
168 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
170 HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
174 * This function must be called with interrupts disabled and preemption off
175 * in order to insure that the setup succeeds in a deterministic time frame.
176 * It will check if the interrupt setup succeeded.
178 static int mmtimer_setup(int cpu, int comparator, unsigned long expires)
181 switch (comparator) {
183 mmtimer_setup_int_0(cpu, expires);
186 mmtimer_setup_int_1(cpu, expires);
189 mmtimer_setup_int_2(cpu, expires);
192 /* We might've missed our expiration time */
193 if (rtc_time() <= expires)
197 * If an interrupt is already pending then its okay
198 * if not then we failed
200 return mmtimer_int_pending(comparator);
203 static int mmtimer_disable_int(long nasid, int comparator)
205 switch (comparator) {
207 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
208 0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
211 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
212 0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
215 nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
216 0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
224 #define COMPARATOR 1 /* The comparator to use */
226 #define TIMER_OFF 0xbadcabLL /* Timer is not setup */
227 #define TIMER_SET 0 /* Comparator is set for this timer */
229 /* There is one of these for each timer */
232 struct k_itimer *timer;
236 struct mmtimer_node {
237 spinlock_t lock ____cacheline_aligned;
238 struct rb_root timer_head;
239 struct rb_node *next;
240 struct tasklet_struct tasklet;
242 static struct mmtimer_node *timers;
246 * Add a new mmtimer struct to the node's mmtimer list.
247 * This function assumes the struct mmtimer_node is locked.
249 static void mmtimer_add_list(struct mmtimer *n)
251 int nodeid = n->timer->it.mmtimer.node;
252 unsigned long expires = n->timer->it.mmtimer.expires;
253 struct rb_node **link = &timers[nodeid].timer_head.rb_node;
254 struct rb_node *parent = NULL;
258 * Find the right place in the rbtree:
262 x = rb_entry(parent, struct mmtimer, list);
264 if (expires < x->timer->it.mmtimer.expires)
265 link = &(*link)->rb_left;
267 link = &(*link)->rb_right;
271 * Insert the timer to the rbtree and check whether it
272 * replaces the first pending timer
274 rb_link_node(&n->list, parent, link);
275 rb_insert_color(&n->list, &timers[nodeid].timer_head);
277 if (!timers[nodeid].next || expires < rb_entry(timers[nodeid].next,
278 struct mmtimer, list)->timer->it.mmtimer.expires)
279 timers[nodeid].next = &n->list;
283 * Set the comparator for the next timer.
284 * This function assumes the struct mmtimer_node is locked.
286 static void mmtimer_set_next_timer(int nodeid)
288 struct mmtimer_node *n = &timers[nodeid];
297 x = rb_entry(n->next, struct mmtimer, list);
299 if (!t->it.mmtimer.incr) {
300 /* Not an interval timer */
301 if (!mmtimer_setup(x->cpu, COMPARATOR,
302 t->it.mmtimer.expires)) {
303 /* Late setup, fire now */
304 tasklet_schedule(&n->tasklet);
311 while (!mmtimer_setup(x->cpu, COMPARATOR, t->it.mmtimer.expires)) {
313 struct rb_node *next;
314 t->it.mmtimer.expires += t->it.mmtimer.incr << o;
315 t->it_overrun += 1 << o;
318 printk(KERN_ALERT "mmtimer: cannot reschedule timer\n");
319 t->it.mmtimer.clock = TIMER_OFF;
320 n->next = rb_next(&x->list);
321 rb_erase(&x->list, &n->timer_head);
326 e = t->it.mmtimer.expires;
327 next = rb_next(&x->list);
332 e1 = rb_entry(next, struct mmtimer, list)->
333 timer->it.mmtimer.expires;
336 rb_erase(&x->list, &n->timer_head);
344 * mmtimer_ioctl - ioctl interface for /dev/mmtimer
345 * @file: file structure for the device
346 * @cmd: command to execute
347 * @arg: optional argument to command
349 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
354 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
355 * of the page where the registers are mapped) for the counter in question.
357 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
360 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
363 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
365 * %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
367 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
368 * in the address specified by @arg.
370 static long mmtimer_ioctl(struct file *file, unsigned int cmd,
375 mutex_lock(&mmtimer_mutex);
378 case MMTIMER_GETOFFSET: /* offset of the counter */
380 * SN RTC registers are on their own 64k page
382 if(PAGE_SIZE <= (1 << 16))
383 ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
388 case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
389 if(copy_to_user((unsigned long __user *)arg,
390 &mmtimer_femtoperiod, sizeof(unsigned long)))
394 case MMTIMER_GETFREQ: /* frequency in Hz */
395 if(copy_to_user((unsigned long __user *)arg,
396 &sn_rtc_cycles_per_second,
397 sizeof(unsigned long)))
401 case MMTIMER_GETBITS: /* number of bits in the clock */
405 case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
406 ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
409 case MMTIMER_GETCOUNTER:
410 if(copy_to_user((unsigned long __user *)arg,
411 RTC_COUNTER_ADDR, sizeof(unsigned long)))
418 mutex_unlock(&mmtimer_mutex);
423 * mmtimer_mmap - maps the clock's registers into userspace
424 * @file: file structure for the device
425 * @vma: VMA to map the registers into
427 * Calls remap_pfn_range() to map the clock's registers into
428 * the calling process' address space.
430 static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
432 unsigned long mmtimer_addr;
434 if (vma->vm_end - vma->vm_start != PAGE_SIZE)
437 if (vma->vm_flags & VM_WRITE)
440 if (PAGE_SIZE > (1 << 16))
443 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
445 mmtimer_addr = __pa(RTC_COUNTER_ADDR);
446 mmtimer_addr &= ~(PAGE_SIZE - 1);
447 mmtimer_addr &= 0xfffffffffffffffUL;
449 if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
450 PAGE_SIZE, vma->vm_page_prot)) {
451 printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
458 static struct miscdevice mmtimer_miscdev = {
464 static struct timespec sgi_clock_offset;
465 static int sgi_clock_period;
468 * Posix Timer Interface
471 static struct timespec sgi_clock_offset;
472 static int sgi_clock_period;
474 static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
478 nsec = rtc_time() * sgi_clock_period
479 + sgi_clock_offset.tv_nsec;
480 *tp = ns_to_timespec(nsec);
481 tp->tv_sec += sgi_clock_offset.tv_sec;
485 static int sgi_clock_set(clockid_t clockid, struct timespec *tp)
491 nsec = rtc_time() * sgi_clock_period;
493 sgi_clock_offset.tv_sec = tp->tv_sec - div_u64_rem(nsec, NSEC_PER_SEC, &rem);
495 if (rem <= tp->tv_nsec)
496 sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
498 sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
499 sgi_clock_offset.tv_sec--;
505 * mmtimer_interrupt - timer interrupt handler
507 * @dev_id: device the irq came from
509 * Called when one of the comarators matches the counter, This
510 * routine will send signals to processes that have requested
513 * This interrupt is run in an interrupt context
514 * by the SHUB. It is therefore safe to locally access SHub
518 mmtimer_interrupt(int irq, void *dev_id)
520 unsigned long expires = 0;
521 int result = IRQ_NONE;
522 unsigned indx = cpu_to_node(smp_processor_id());
523 struct mmtimer *base;
525 spin_lock(&timers[indx].lock);
526 base = rb_entry(timers[indx].next, struct mmtimer, list);
528 spin_unlock(&timers[indx].lock);
532 if (base->cpu == smp_processor_id()) {
534 expires = base->timer->it.mmtimer.expires;
535 /* expires test won't work with shared irqs */
536 if ((mmtimer_int_pending(COMPARATOR) > 0) ||
537 (expires && (expires <= rtc_time()))) {
538 mmtimer_clr_int_pending(COMPARATOR);
539 tasklet_schedule(&timers[indx].tasklet);
540 result = IRQ_HANDLED;
543 spin_unlock(&timers[indx].lock);
547 static void mmtimer_tasklet(unsigned long data)
550 struct mmtimer_node *mn = &timers[nodeid];
555 /* Send signal and deal with periodic signals */
556 spin_lock_irqsave(&mn->lock, flags);
560 x = rb_entry(mn->next, struct mmtimer, list);
563 if (t->it.mmtimer.clock == TIMER_OFF)
568 mn->next = rb_next(&x->list);
569 rb_erase(&x->list, &mn->timer_head);
571 if (posix_timer_event(t, 0) != 0)
574 if(t->it.mmtimer.incr) {
575 t->it.mmtimer.expires += t->it.mmtimer.incr;
578 /* Ensure we don't false trigger in mmtimer_interrupt */
579 t->it.mmtimer.clock = TIMER_OFF;
580 t->it.mmtimer.expires = 0;
583 /* Set comparator for next timer, if there is one */
584 mmtimer_set_next_timer(nodeid);
586 t->it_overrun_last = t->it_overrun;
588 spin_unlock_irqrestore(&mn->lock, flags);
591 static int sgi_timer_create(struct k_itimer *timer)
593 /* Insure that a newly created timer is off */
594 timer->it.mmtimer.clock = TIMER_OFF;
598 /* This does not really delete a timer. It just insures
599 * that the timer is not active
601 * Assumption: it_lock is already held with irq's disabled
603 static int sgi_timer_del(struct k_itimer *timr)
605 cnodeid_t nodeid = timr->it.mmtimer.node;
606 unsigned long irqflags;
608 spin_lock_irqsave(&timers[nodeid].lock, irqflags);
609 if (timr->it.mmtimer.clock != TIMER_OFF) {
610 unsigned long expires = timr->it.mmtimer.expires;
611 struct rb_node *n = timers[nodeid].timer_head.rb_node;
612 struct mmtimer *uninitialized_var(t);
615 timr->it.mmtimer.clock = TIMER_OFF;
616 timr->it.mmtimer.expires = 0;
619 t = rb_entry(n, struct mmtimer, list);
620 if (t->timer == timr)
623 if (expires < t->timer->it.mmtimer.expires)
630 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
634 if (timers[nodeid].next == n) {
635 timers[nodeid].next = rb_next(n);
639 rb_erase(n, &timers[nodeid].timer_head);
643 mmtimer_disable_int(cnodeid_to_nasid(nodeid),
645 mmtimer_set_next_timer(nodeid);
648 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
652 /* Assumption: it_lock is already held with irq's disabled */
653 static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
656 if (timr->it.mmtimer.clock == TIMER_OFF) {
657 cur_setting->it_interval.tv_nsec = 0;
658 cur_setting->it_interval.tv_sec = 0;
659 cur_setting->it_value.tv_nsec = 0;
660 cur_setting->it_value.tv_sec =0;
664 cur_setting->it_interval = ns_to_timespec(timr->it.mmtimer.incr * sgi_clock_period);
665 cur_setting->it_value = ns_to_timespec((timr->it.mmtimer.expires - rtc_time()) * sgi_clock_period);
669 static int sgi_timer_set(struct k_itimer *timr, int flags,
670 struct itimerspec * new_setting,
671 struct itimerspec * old_setting)
673 unsigned long when, period, irqflags;
676 struct mmtimer *base;
680 sgi_timer_get(timr, old_setting);
683 when = timespec_to_ns(&new_setting->it_value);
684 period = timespec_to_ns(&new_setting->it_interval);
690 base = kmalloc(sizeof(struct mmtimer), GFP_KERNEL);
694 if (flags & TIMER_ABSTIME) {
699 now = timespec_to_ns(&n);
703 /* Fire the timer immediately */
708 * Convert to sgi clock period. Need to keep rtc_time() as near as possible
709 * to getnstimeofday() in order to be as faithful as possible to the time
712 when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
713 period = (period + sgi_clock_period - 1) / sgi_clock_period;
716 * We are allocating a local SHub comparator. If we would be moved to another
717 * cpu then another SHub may be local to us. Prohibit that by switching off
722 nodeid = cpu_to_node(smp_processor_id());
724 /* Lock the node timer structure */
725 spin_lock_irqsave(&timers[nodeid].lock, irqflags);
728 base->cpu = smp_processor_id();
730 timr->it.mmtimer.clock = TIMER_SET;
731 timr->it.mmtimer.node = nodeid;
732 timr->it.mmtimer.incr = period;
733 timr->it.mmtimer.expires = when;
735 n = timers[nodeid].next;
737 /* Add the new struct mmtimer to node's timer list */
738 mmtimer_add_list(base);
740 if (timers[nodeid].next == n) {
741 /* No need to reprogram comparator for now */
742 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
747 /* We need to reprogram the comparator */
749 mmtimer_disable_int(cnodeid_to_nasid(nodeid), COMPARATOR);
751 mmtimer_set_next_timer(nodeid);
753 /* Unlock the node timer structure */
754 spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
761 static struct k_clock sgi_clock = {
763 .clock_set = sgi_clock_set,
764 .clock_get = sgi_clock_get,
765 .timer_create = sgi_timer_create,
766 .nsleep = do_posix_clock_nonanosleep,
767 .timer_set = sgi_timer_set,
768 .timer_del = sgi_timer_del,
769 .timer_get = sgi_timer_get
773 * mmtimer_init - device initialization routine
775 * Does initial setup for the mmtimer device.
777 static int __init mmtimer_init(void)
779 cnodeid_t node, maxn = -1;
781 if (!ia64_platform_is("sn2"))
785 * Sanity check the cycles/sec variable
787 if (sn_rtc_cycles_per_second < 100000) {
788 printk(KERN_ERR "%s: unable to determine clock frequency\n",
793 mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
794 2) / sn_rtc_cycles_per_second;
796 if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, IRQF_PERCPU, MMTIMER_NAME, NULL)) {
797 printk(KERN_WARNING "%s: unable to allocate interrupt.",
802 if (misc_register(&mmtimer_miscdev)) {
803 printk(KERN_ERR "%s: failed to register device\n",
808 /* Get max numbered node, calculate slots needed */
809 for_each_online_node(node) {
814 /* Allocate list of node ptrs to mmtimer_t's */
815 timers = kzalloc(sizeof(struct mmtimer_node)*maxn, GFP_KERNEL);
816 if (timers == NULL) {
817 printk(KERN_ERR "%s: failed to allocate memory for device\n",
822 /* Initialize struct mmtimer's for each online node */
823 for_each_online_node(node) {
824 spin_lock_init(&timers[node].lock);
825 tasklet_init(&timers[node].tasklet, mmtimer_tasklet,
826 (unsigned long) node);
829 sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
830 register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);
832 printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
833 sn_rtc_cycles_per_second/(unsigned long)1E6);
839 misc_deregister(&mmtimer_miscdev);
841 free_irq(SGI_MMTIMER_VECTOR, NULL);
846 module_init(mmtimer_init);