linux/drivers/char/mmtimer.c
<<
>>
Prefs
   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) {
 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        misc_deregister(&mmtimer_miscdev);
 852out2:
 853        free_irq(SGI_MMTIMER_VECTOR, NULL);
 854out1:
 855        return -1;
 856}
 857
 858module_init(mmtimer_init);
 859
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.