Root/drivers/char/mmtimer.c

1/*
2 * Timer device implementation for SGI SN platforms.
3 *
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
6 * for more details.
7 *
8 * Copyright (c) 2001-2006 Silicon Graphics, Inc. All rights reserved.
9 *
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
12 * SHub RTC, however.
13 *
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
19 */
20
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>
27#include <linux/mm.h>
28#include <linux/fs.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>
37
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>
44
45MODULE_AUTHOR("Jesse Barnes <jbarnes@sgi.com>");
46MODULE_DESCRIPTION("SGI Altix RTC Timer");
47MODULE_LICENSE("GPL");
48
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"
53
54#define RTC_BITS 55 /* 55 bits for this implementation */
55
56static struct k_clock sgi_clock;
57
58extern unsigned long sn_rtc_cycles_per_second;
59
60#define RTC_COUNTER_ADDR ((long *)LOCAL_MMR_ADDR(SH_RTC))
61
62#define rtc_time() (*RTC_COUNTER_ADDR)
63
64static DEFINE_MUTEX(mmtimer_mutex);
65static long mmtimer_ioctl(struct file *file, unsigned int cmd,
66                        unsigned long arg);
67static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
68
69/*
70 * Period in femtoseconds (10^-15 s)
71 */
72static unsigned long mmtimer_femtoperiod = 0;
73
74static const struct file_operations mmtimer_fops = {
75    .owner = THIS_MODULE,
76    .mmap = mmtimer_mmap,
77    .unlocked_ioctl = mmtimer_ioctl,
78    .llseek = noop_llseek,
79};
80
81/*
82 * We only have comparison registers RTC1-4 currently available per
83 * node. RTC0 is used by SAL.
84 */
85/* Check for an RTC interrupt pending */
86static int mmtimer_int_pending(int comparator)
87{
88    if (HUB_L((unsigned long *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED)) &
89            SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator)
90        return 1;
91    else
92        return 0;
93}
94
95/* Clear the RTC interrupt pending bit */
96static void mmtimer_clr_int_pending(int comparator)
97{
98    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_EVENT_OCCURRED_ALIAS),
99        SH_EVENT_OCCURRED_RTC1_INT_MASK << comparator);
100}
101
102/* Setup timer on comparator RTC1 */
103static void mmtimer_setup_int_0(int cpu, u64 expires)
104{
105    u64 val;
106
107    /* Disable interrupt */
108    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 0UL);
109
110    /* Initialize comparator value */
111    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), -1L);
112
113    /* Clear pending bit */
114    mmtimer_clr_int_pending(0);
115
116    val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC1_INT_CONFIG_IDX_SHFT) |
117        ((u64)cpu_physical_id(cpu) <<
118            SH_RTC1_INT_CONFIG_PID_SHFT);
119
120    /* Set configuration */
121    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_CONFIG), val);
122
123    /* Enable RTC interrupts */
124    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE), 1UL);
125
126    /* Initialize comparator value */
127    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPB), expires);
128
129
130}
131
132/* Setup timer on comparator RTC2 */
133static void mmtimer_setup_int_1(int cpu, u64 expires)
134{
135    u64 val;
136
137    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 0UL);
138
139    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), -1L);
140
141    mmtimer_clr_int_pending(1);
142
143    val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC2_INT_CONFIG_IDX_SHFT) |
144        ((u64)cpu_physical_id(cpu) <<
145            SH_RTC2_INT_CONFIG_PID_SHFT);
146
147    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_CONFIG), val);
148
149    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE), 1UL);
150
151    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPC), expires);
152}
153
154/* Setup timer on comparator RTC3 */
155static void mmtimer_setup_int_2(int cpu, u64 expires)
156{
157    u64 val;
158
159    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 0UL);
160
161    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), -1L);
162
163    mmtimer_clr_int_pending(2);
164
165    val = ((u64)SGI_MMTIMER_VECTOR << SH_RTC3_INT_CONFIG_IDX_SHFT) |
166        ((u64)cpu_physical_id(cpu) <<
167            SH_RTC3_INT_CONFIG_PID_SHFT);
168
169    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_CONFIG), val);
170
171    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE), 1UL);
172
173    HUB_S((u64 *)LOCAL_MMR_ADDR(SH_INT_CMPD), expires);
174}
175
176/*
177 * This function must be called with interrupts disabled and preemption off
178 * in order to insure that the setup succeeds in a deterministic time frame.
179 * It will check if the interrupt setup succeeded.
180 */
181static int mmtimer_setup(int cpu, int comparator, unsigned long expires,
182    u64 *set_completion_time)
183{
184    switch (comparator) {
185    case 0:
186        mmtimer_setup_int_0(cpu, expires);
187        break;
188    case 1:
189        mmtimer_setup_int_1(cpu, expires);
190        break;
191    case 2:
192        mmtimer_setup_int_2(cpu, expires);
193        break;
194    }
195    /* We might've missed our expiration time */
196    *set_completion_time = rtc_time();
197    if (*set_completion_time <= expires)
198        return 1;
199
200    /*
201     * If an interrupt is already pending then its okay
202     * if not then we failed
203     */
204    return mmtimer_int_pending(comparator);
205}
206
207static int mmtimer_disable_int(long nasid, int comparator)
208{
209    switch (comparator) {
210    case 0:
211        nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC1_INT_ENABLE),
212            0UL) : REMOTE_HUB_S(nasid, SH_RTC1_INT_ENABLE, 0UL);
213        break;
214    case 1:
215        nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC2_INT_ENABLE),
216            0UL) : REMOTE_HUB_S(nasid, SH_RTC2_INT_ENABLE, 0UL);
217        break;
218    case 2:
219        nasid == -1 ? HUB_S((u64 *)LOCAL_MMR_ADDR(SH_RTC3_INT_ENABLE),
220            0UL) : REMOTE_HUB_S(nasid, SH_RTC3_INT_ENABLE, 0UL);
221        break;
222    default:
223        return -EFAULT;
224    }
225    return 0;
226}
227
228#define COMPARATOR 1 /* The comparator to use */
229
230#define TIMER_OFF 0xbadcabLL /* Timer is not setup */
231#define TIMER_SET 0 /* Comparator is set for this timer */
232
233#define MMTIMER_INTERVAL_RETRY_INCREMENT_DEFAULT 40
234
235/* There is one of these for each timer */
236struct mmtimer {
237    struct rb_node list;
238    struct k_itimer *timer;
239    int cpu;
240};
241
242struct mmtimer_node {
243    spinlock_t lock ____cacheline_aligned;
244    struct rb_root timer_head;
245    struct rb_node *next;
246    struct tasklet_struct tasklet;
247};
248static struct mmtimer_node *timers;
249
250static unsigned mmtimer_interval_retry_increment =
251    MMTIMER_INTERVAL_RETRY_INCREMENT_DEFAULT;
252module_param(mmtimer_interval_retry_increment, uint, 0644);
253MODULE_PARM_DESC(mmtimer_interval_retry_increment,
254    "RTC ticks to add to expiration on interval retry (default 40)");
255
256/*
257 * Add a new mmtimer struct to the node's mmtimer list.
258 * This function assumes the struct mmtimer_node is locked.
259 */
260static void mmtimer_add_list(struct mmtimer *n)
261{
262    int nodeid = n->timer->it.mmtimer.node;
263    unsigned long expires = n->timer->it.mmtimer.expires;
264    struct rb_node **link = &timers[nodeid].timer_head.rb_node;
265    struct rb_node *parent = NULL;
266    struct mmtimer *x;
267
268    /*
269     * Find the right place in the rbtree:
270     */
271    while (*link) {
272        parent = *link;
273        x = rb_entry(parent, struct mmtimer, list);
274
275        if (expires < x->timer->it.mmtimer.expires)
276            link = &(*link)->rb_left;
277        else
278            link = &(*link)->rb_right;
279    }
280
281    /*
282     * Insert the timer to the rbtree and check whether it
283     * replaces the first pending timer
284     */
285    rb_link_node(&n->list, parent, link);
286    rb_insert_color(&n->list, &timers[nodeid].timer_head);
287
288    if (!timers[nodeid].next || expires < rb_entry(timers[nodeid].next,
289            struct mmtimer, list)->timer->it.mmtimer.expires)
290        timers[nodeid].next = &n->list;
291}
292
293/*
294 * Set the comparator for the next timer.
295 * This function assumes the struct mmtimer_node is locked.
296 */
297static void mmtimer_set_next_timer(int nodeid)
298{
299    struct mmtimer_node *n = &timers[nodeid];
300    struct mmtimer *x;
301    struct k_itimer *t;
302    u64 expires, exp, set_completion_time;
303    int i;
304
305restart:
306    if (n->next == NULL)
307        return;
308
309    x = rb_entry(n->next, struct mmtimer, list);
310    t = x->timer;
311    if (!t->it.mmtimer.incr) {
312        /* Not an interval timer */
313        if (!mmtimer_setup(x->cpu, COMPARATOR,
314                    t->it.mmtimer.expires,
315                    &set_completion_time)) {
316            /* Late setup, fire now */
317            tasklet_schedule(&n->tasklet);
318        }
319        return;
320    }
321
322    /* Interval timer */
323    i = 0;
324    expires = exp = t->it.mmtimer.expires;
325    while (!mmtimer_setup(x->cpu, COMPARATOR, expires,
326                &set_completion_time)) {
327        int to;
328
329        i++;
330        expires = set_completion_time +
331                mmtimer_interval_retry_increment + (1 << i);
332        /* Calculate overruns as we go. */
333        to = ((u64)(expires - exp) / t->it.mmtimer.incr);
334        if (to) {
335            t->it_overrun += to;
336            t->it.mmtimer.expires += t->it.mmtimer.incr * to;
337            exp = t->it.mmtimer.expires;
338        }
339        if (i > 20) {
340            printk(KERN_ALERT "mmtimer: cannot reschedule timer\n");
341            t->it.mmtimer.clock = TIMER_OFF;
342            n->next = rb_next(&x->list);
343            rb_erase(&x->list, &n->timer_head);
344            kfree(x);
345            goto restart;
346        }
347    }
348}
349
350/**
351 * mmtimer_ioctl - ioctl interface for /dev/mmtimer
352 * @file: file structure for the device
353 * @cmd: command to execute
354 * @arg: optional argument to command
355 *
356 * Executes the command specified by @cmd. Returns 0 for success, < 0 for
357 * failure.
358 *
359 * Valid commands:
360 *
361 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
362 * of the page where the registers are mapped) for the counter in question.
363 *
364 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
365 * seconds
366 *
367 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
368 * specified by @arg
369 *
370 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
371 *
372 * %MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
373 *
374 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
375 * in the address specified by @arg.
376 */
377static long mmtimer_ioctl(struct file *file, unsigned int cmd,
378                        unsigned long arg)
379{
380    int ret = 0;
381
382    mutex_lock(&mmtimer_mutex);
383
384    switch (cmd) {
385    case MMTIMER_GETOFFSET: /* offset of the counter */
386        /*
387         * SN RTC registers are on their own 64k page
388         */
389        if(PAGE_SIZE <= (1 << 16))
390            ret = (((long)RTC_COUNTER_ADDR) & (PAGE_SIZE-1)) / 8;
391        else
392            ret = -ENOSYS;
393        break;
394
395    case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
396        if(copy_to_user((unsigned long __user *)arg,
397                &mmtimer_femtoperiod, sizeof(unsigned long)))
398            ret = -EFAULT;
399        break;
400
401    case MMTIMER_GETFREQ: /* frequency in Hz */
402        if(copy_to_user((unsigned long __user *)arg,
403                &sn_rtc_cycles_per_second,
404                sizeof(unsigned long)))
405            ret = -EFAULT;
406        break;
407
408    case MMTIMER_GETBITS: /* number of bits in the clock */
409        ret = RTC_BITS;
410        break;
411
412    case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
413        ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
414        break;
415
416    case MMTIMER_GETCOUNTER:
417        if(copy_to_user((unsigned long __user *)arg,
418                RTC_COUNTER_ADDR, sizeof(unsigned long)))
419            ret = -EFAULT;
420        break;
421    default:
422        ret = -ENOTTY;
423        break;
424    }
425    mutex_unlock(&mmtimer_mutex);
426    return ret;
427}
428
429/**
430 * mmtimer_mmap - maps the clock's registers into userspace
431 * @file: file structure for the device
432 * @vma: VMA to map the registers into
433 *
434 * Calls remap_pfn_range() to map the clock's registers into
435 * the calling process' address space.
436 */
437static int mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
438{
439    unsigned long mmtimer_addr;
440
441    if (vma->vm_end - vma->vm_start != PAGE_SIZE)
442        return -EINVAL;
443
444    if (vma->vm_flags & VM_WRITE)
445        return -EPERM;
446
447    if (PAGE_SIZE > (1 << 16))
448        return -ENOSYS;
449
450    vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
451
452    mmtimer_addr = __pa(RTC_COUNTER_ADDR);
453    mmtimer_addr &= ~(PAGE_SIZE - 1);
454    mmtimer_addr &= 0xfffffffffffffffUL;
455
456    if (remap_pfn_range(vma, vma->vm_start, mmtimer_addr >> PAGE_SHIFT,
457                    PAGE_SIZE, vma->vm_page_prot)) {
458        printk(KERN_ERR "remap_pfn_range failed in mmtimer.c\n");
459        return -EAGAIN;
460    }
461
462    return 0;
463}
464
465static struct miscdevice mmtimer_miscdev = {
466    SGI_MMTIMER,
467    MMTIMER_NAME,
468    &mmtimer_fops
469};
470
471static struct timespec sgi_clock_offset;
472static int sgi_clock_period;
473
474/*
475 * Posix Timer Interface
476 */
477
478static struct timespec sgi_clock_offset;
479static int sgi_clock_period;
480
481static int sgi_clock_get(clockid_t clockid, struct timespec *tp)
482{
483    u64 nsec;
484
485    nsec = rtc_time() * sgi_clock_period
486            + sgi_clock_offset.tv_nsec;
487    *tp = ns_to_timespec(nsec);
488    tp->tv_sec += sgi_clock_offset.tv_sec;
489    return 0;
490};
491
492static int sgi_clock_set(const clockid_t clockid, const struct timespec *tp)
493{
494
495    u64 nsec;
496    u32 rem;
497
498    nsec = rtc_time() * sgi_clock_period;
499
500    sgi_clock_offset.tv_sec = tp->tv_sec - div_u64_rem(nsec, NSEC_PER_SEC, &rem);
501
502    if (rem <= tp->tv_nsec)
503        sgi_clock_offset.tv_nsec = tp->tv_sec - rem;
504    else {
505        sgi_clock_offset.tv_nsec = tp->tv_sec + NSEC_PER_SEC - rem;
506        sgi_clock_offset.tv_sec--;
507    }
508    return 0;
509}
510
511/**
512 * mmtimer_interrupt - timer interrupt handler
513 * @irq: irq received
514 * @dev_id: device the irq came from
515 *
516 * Called when one of the comarators matches the counter, This
517 * routine will send signals to processes that have requested
518 * them.
519 *
520 * This interrupt is run in an interrupt context
521 * by the SHUB. It is therefore safe to locally access SHub
522 * registers.
523 */
524static irqreturn_t
525mmtimer_interrupt(int irq, void *dev_id)
526{
527    unsigned long expires = 0;
528    int result = IRQ_NONE;
529    unsigned indx = cpu_to_node(smp_processor_id());
530    struct mmtimer *base;
531
532    spin_lock(&timers[indx].lock);
533    base = rb_entry(timers[indx].next, struct mmtimer, list);
534    if (base == NULL) {
535        spin_unlock(&timers[indx].lock);
536        return result;
537    }
538
539    if (base->cpu == smp_processor_id()) {
540        if (base->timer)
541            expires = base->timer->it.mmtimer.expires;
542        /* expires test won't work with shared irqs */
543        if ((mmtimer_int_pending(COMPARATOR) > 0) ||
544            (expires && (expires <= rtc_time()))) {
545            mmtimer_clr_int_pending(COMPARATOR);
546            tasklet_schedule(&timers[indx].tasklet);
547            result = IRQ_HANDLED;
548        }
549    }
550    spin_unlock(&timers[indx].lock);
551    return result;
552}
553
554static void mmtimer_tasklet(unsigned long data)
555{
556    int nodeid = data;
557    struct mmtimer_node *mn = &timers[nodeid];
558    struct mmtimer *x;
559    struct k_itimer *t;
560    unsigned long flags;
561
562    /* Send signal and deal with periodic signals */
563    spin_lock_irqsave(&mn->lock, flags);
564    if (!mn->next)
565        goto out;
566
567    x = rb_entry(mn->next, struct mmtimer, list);
568    t = x->timer;
569
570    if (t->it.mmtimer.clock == TIMER_OFF)
571        goto out;
572
573    t->it_overrun = 0;
574
575    mn->next = rb_next(&x->list);
576    rb_erase(&x->list, &mn->timer_head);
577
578    if (posix_timer_event(t, 0) != 0)
579        t->it_overrun++;
580
581    if(t->it.mmtimer.incr) {
582        t->it.mmtimer.expires += t->it.mmtimer.incr;
583        mmtimer_add_list(x);
584    } else {
585        /* Ensure we don't false trigger in mmtimer_interrupt */
586        t->it.mmtimer.clock = TIMER_OFF;
587        t->it.mmtimer.expires = 0;
588        kfree(x);
589    }
590    /* Set comparator for next timer, if there is one */
591    mmtimer_set_next_timer(nodeid);
592
593    t->it_overrun_last = t->it_overrun;
594out:
595    spin_unlock_irqrestore(&mn->lock, flags);
596}
597
598static int sgi_timer_create(struct k_itimer *timer)
599{
600    /* Insure that a newly created timer is off */
601    timer->it.mmtimer.clock = TIMER_OFF;
602    return 0;
603}
604
605/* This does not really delete a timer. It just insures
606 * that the timer is not active
607 *
608 * Assumption: it_lock is already held with irq's disabled
609 */
610static int sgi_timer_del(struct k_itimer *timr)
611{
612    cnodeid_t nodeid = timr->it.mmtimer.node;
613    unsigned long irqflags;
614
615    spin_lock_irqsave(&timers[nodeid].lock, irqflags);
616    if (timr->it.mmtimer.clock != TIMER_OFF) {
617        unsigned long expires = timr->it.mmtimer.expires;
618        struct rb_node *n = timers[nodeid].timer_head.rb_node;
619        struct mmtimer *uninitialized_var(t);
620        int r = 0;
621
622        timr->it.mmtimer.clock = TIMER_OFF;
623        timr->it.mmtimer.expires = 0;
624
625        while (n) {
626            t = rb_entry(n, struct mmtimer, list);
627            if (t->timer == timr)
628                break;
629
630            if (expires < t->timer->it.mmtimer.expires)
631                n = n->rb_left;
632            else
633                n = n->rb_right;
634        }
635
636        if (!n) {
637            spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
638            return 0;
639        }
640
641        if (timers[nodeid].next == n) {
642            timers[nodeid].next = rb_next(n);
643            r = 1;
644        }
645
646        rb_erase(n, &timers[nodeid].timer_head);
647        kfree(t);
648
649        if (r) {
650            mmtimer_disable_int(cnodeid_to_nasid(nodeid),
651                COMPARATOR);
652            mmtimer_set_next_timer(nodeid);
653        }
654    }
655    spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
656    return 0;
657}
658
659/* Assumption: it_lock is already held with irq's disabled */
660static void sgi_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
661{
662
663    if (timr->it.mmtimer.clock == TIMER_OFF) {
664        cur_setting->it_interval.tv_nsec = 0;
665        cur_setting->it_interval.tv_sec = 0;
666        cur_setting->it_value.tv_nsec = 0;
667        cur_setting->it_value.tv_sec =0;
668        return;
669    }
670
671    cur_setting->it_interval = ns_to_timespec(timr->it.mmtimer.incr * sgi_clock_period);
672    cur_setting->it_value = ns_to_timespec((timr->it.mmtimer.expires - rtc_time()) * sgi_clock_period);
673}
674
675
676static int sgi_timer_set(struct k_itimer *timr, int flags,
677    struct itimerspec * new_setting,
678    struct itimerspec * old_setting)
679{
680    unsigned long when, period, irqflags;
681    int err = 0;
682    cnodeid_t nodeid;
683    struct mmtimer *base;
684    struct rb_node *n;
685
686    if (old_setting)
687        sgi_timer_get(timr, old_setting);
688
689    sgi_timer_del(timr);
690    when = timespec_to_ns(&new_setting->it_value);
691    period = timespec_to_ns(&new_setting->it_interval);
692
693    if (when == 0)
694        /* Clear timer */
695        return 0;
696
697    base = kmalloc(sizeof(struct mmtimer), GFP_KERNEL);
698    if (base == NULL)
699        return -ENOMEM;
700
701    if (flags & TIMER_ABSTIME) {
702        struct timespec n;
703        unsigned long now;
704
705        getnstimeofday(&n);
706        now = timespec_to_ns(&n);
707        if (when > now)
708            when -= now;
709        else
710            /* Fire the timer immediately */
711            when = 0;
712    }
713
714    /*
715     * Convert to sgi clock period. Need to keep rtc_time() as near as possible
716     * to getnstimeofday() in order to be as faithful as possible to the time
717     * specified.
718     */
719    when = (when + sgi_clock_period - 1) / sgi_clock_period + rtc_time();
720    period = (period + sgi_clock_period - 1) / sgi_clock_period;
721
722    /*
723     * We are allocating a local SHub comparator. If we would be moved to another
724     * cpu then another SHub may be local to us. Prohibit that by switching off
725     * preemption.
726     */
727    preempt_disable();
728
729    nodeid = cpu_to_node(smp_processor_id());
730
731    /* Lock the node timer structure */
732    spin_lock_irqsave(&timers[nodeid].lock, irqflags);
733
734    base->timer = timr;
735    base->cpu = smp_processor_id();
736
737    timr->it.mmtimer.clock = TIMER_SET;
738    timr->it.mmtimer.node = nodeid;
739    timr->it.mmtimer.incr = period;
740    timr->it.mmtimer.expires = when;
741
742    n = timers[nodeid].next;
743
744    /* Add the new struct mmtimer to node's timer list */
745    mmtimer_add_list(base);
746
747    if (timers[nodeid].next == n) {
748        /* No need to reprogram comparator for now */
749        spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
750        preempt_enable();
751        return err;
752    }
753
754    /* We need to reprogram the comparator */
755    if (n)
756        mmtimer_disable_int(cnodeid_to_nasid(nodeid), COMPARATOR);
757
758    mmtimer_set_next_timer(nodeid);
759
760    /* Unlock the node timer structure */
761    spin_unlock_irqrestore(&timers[nodeid].lock, irqflags);
762
763    preempt_enable();
764
765    return err;
766}
767
768static int sgi_clock_getres(const clockid_t which_clock, struct timespec *tp)
769{
770    tp->tv_sec = 0;
771    tp->tv_nsec = sgi_clock_period;
772    return 0;
773}
774
775static struct k_clock sgi_clock = {
776    .clock_set = sgi_clock_set,
777    .clock_get = sgi_clock_get,
778    .clock_getres = sgi_clock_getres,
779    .timer_create = sgi_timer_create,
780    .timer_set = sgi_timer_set,
781    .timer_del = sgi_timer_del,
782    .timer_get = sgi_timer_get
783};
784
785/**
786 * mmtimer_init - device initialization routine
787 *
788 * Does initial setup for the mmtimer device.
789 */
790static int __init mmtimer_init(void)
791{
792    cnodeid_t node, maxn = -1;
793
794    if (!ia64_platform_is("sn2"))
795        return 0;
796
797    /*
798     * Sanity check the cycles/sec variable
799     */
800    if (sn_rtc_cycles_per_second < 100000) {
801        printk(KERN_ERR "%s: unable to determine clock frequency\n",
802               MMTIMER_NAME);
803        goto out1;
804    }
805
806    mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
807                   2) / sn_rtc_cycles_per_second;
808
809    if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, IRQF_PERCPU, MMTIMER_NAME, NULL)) {
810        printk(KERN_WARNING "%s: unable to allocate interrupt.",
811            MMTIMER_NAME);
812        goto out1;
813    }
814
815    if (misc_register(&mmtimer_miscdev)) {
816        printk(KERN_ERR "%s: failed to register device\n",
817               MMTIMER_NAME);
818        goto out2;
819    }
820
821    /* Get max numbered node, calculate slots needed */
822    for_each_online_node(node) {
823        maxn = node;
824    }
825    maxn++;
826
827    /* Allocate list of node ptrs to mmtimer_t's */
828    timers = kzalloc(sizeof(struct mmtimer_node)*maxn, GFP_KERNEL);
829    if (timers == NULL) {
830        printk(KERN_ERR "%s: failed to allocate memory for device\n",
831                MMTIMER_NAME);
832        goto out3;
833    }
834
835    /* Initialize struct mmtimer's for each online node */
836    for_each_online_node(node) {
837        spin_lock_init(&timers[node].lock);
838        tasklet_init(&timers[node].tasklet, mmtimer_tasklet,
839            (unsigned long) node);
840    }
841
842    sgi_clock_period = NSEC_PER_SEC / sn_rtc_cycles_per_second;
843    posix_timers_register_clock(CLOCK_SGI_CYCLE, &sgi_clock);
844
845    printk(KERN_INFO "%s: v%s, %ld MHz\n", MMTIMER_DESC, MMTIMER_VERSION,
846           sn_rtc_cycles_per_second/(unsigned long)1E6);
847
848    return 0;
849
850out3:
851    kfree(timers);
852    misc_deregister(&mmtimer_miscdev);
853out2:
854    free_irq(SGI_MMTIMER_VECTOR, NULL);
855out1:
856    return -1;
857}
858
859module_init(mmtimer_init);
860

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