arch/x86/kernel/uv_time.c

   1 /*
   2  * SGI RTC clock/timer routines.
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, write to the Free Software
  16  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  17  *
  18  *  Copyright (c) 2009 Silicon Graphics, Inc.  All Rights Reserved.
  19  *  Copyright (c) Dimitri Sivanich
  20  */
  21 #include <linux/clockchips.h>
  22 #include <linux/slab.h>
  23
  24 #include <asm/uv/uv_mmrs.h>
  25 #include <asm/uv/uv_hub.h>
  26 #include <asm/uv/bios.h>
  27 #include <asm/uv/uv.h>
  28 #include <asm/apic.h>
  29 #include <asm/cpu.h>
  30
  31 #define RTC_NAME                "sgi_rtc"
  32
  33 static cycle_t uv_read_rtc(struct clocksource *cs);
  34 static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
  35 static void uv_rtc_timer_setup(enum clock_event_mode,
  36                                 struct clock_event_device *);
  37
  38 static struct clocksource clocksource_uv = {
  39         .name           = RTC_NAME,
  40         .rating         = 400,
  41         .read           = uv_read_rtc,
  42         .mask           = (cycle_t)UVH_RTC_REAL_TIME_CLOCK_MASK,
  43         .shift          = 10,
  44         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  45 };
  46
  47 static struct clock_event_device clock_event_device_uv = {
  48         .name           = RTC_NAME,
  49         .features       = CLOCK_EVT_FEAT_ONESHOT,
  50         .shift          = 20,
  51         .rating         = 400,
  52         .irq            = -1,
  53         .set_next_event = uv_rtc_next_event,
  54         .set_mode       = uv_rtc_timer_setup,
  55         .event_handler  = NULL,
  56 };
  57
  58 static DEFINE_PER_CPU(struct clock_event_device, cpu_ced);
  59
  60 /* There is one of these allocated per node */
  61 struct uv_rtc_timer_head {
  62         spinlock_t      lock;
  63         /* next cpu waiting for timer, local node relative: */
  64         int             next_cpu;
  65         /* number of cpus on this node: */
  66         int             ncpus;
  67         struct {
  68                 int     lcpu;           /* systemwide logical cpu number */
  69                 u64     expires;        /* next timer expiration for this cpu */
  70         } cpu[1];
  71 };
  72
  73 /*
  74  * Access to uv_rtc_timer_head via blade id.
  75  */
  76 static struct uv_rtc_timer_head         **blade_info __read_mostly;
  77
  78 static int                              uv_rtc_evt_enable;
  79
  80 /*
  81  * Hardware interface routines
  82  */
  83
  84 /* Send IPIs to another node */
  85 static void uv_rtc_send_IPI(int cpu)
  86 {
  87         unsigned long apicid, val;
  88         int pnode;
  89
  90         apicid = cpu_physical_id(cpu);
  91         pnode = uv_apicid_to_pnode(apicid);
  92         val = (1UL << UVH_IPI_INT_SEND_SHFT) |
  93               (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
  94               (X86_PLATFORM_IPI_VECTOR << UVH_IPI_INT_VECTOR_SHFT);
  95
  96         uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
  97 }
  98
  99 /* Check for an RTC interrupt pending */
 100 static int uv_intr_pending(int pnode)
 101 {
 102         return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED0) &
 103                 UVH_EVENT_OCCURRED0_RTC1_MASK;
 104 }
 105
 106 /* Setup interrupt and return non-zero if early expiration occurred. */
 107 static int uv_setup_intr(int cpu, u64 expires)
 108 {
 109         u64 val;
 110         int pnode = uv_cpu_to_pnode(cpu);
 111
 112         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 113                 UVH_RTC1_INT_CONFIG_M_MASK);
 114         uv_write_global_mmr64(pnode, UVH_INT_CMPB, -1L);
 115
 116         uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED0_ALIAS,
 117                 UVH_EVENT_OCCURRED0_RTC1_MASK);
 118
 119         val = (X86_PLATFORM_IPI_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
 120                 ((u64)cpu_physical_id(cpu) << UVH_RTC1_INT_CONFIG_APIC_ID_SHFT);
 121
 122         /* Set configuration */
 123         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG, val);
 124         /* Initialize comparator value */
 125         uv_write_global_mmr64(pnode, UVH_INT_CMPB, expires);
 126
 127         if (uv_read_rtc(NULL) <= expires)
 128                 return 0;
 129
 130         return !uv_intr_pending(pnode);
 131 }
 132
 133 /*
 134  * Per-cpu timer tracking routines
 135  */
 136
 137 static __init void uv_rtc_deallocate_timers(void)
 138 {
 139         int bid;
 140
 141         for_each_possible_blade(bid) {
 142                 kfree(blade_info[bid]);
 143         }
 144         kfree(blade_info);
 145 }
 146
 147 /* Allocate per-node list of cpu timer expiration times. */
 148 static __init int uv_rtc_allocate_timers(void)
 149 {
 150         int cpu;
 151
 152         blade_info = kmalloc(uv_possible_blades * sizeof(void *), GFP_KERNEL);
 153         if (!blade_info)
 154                 return -ENOMEM;
 155         memset(blade_info, 0, uv_possible_blades * sizeof(void *));
 156
 157         for_each_present_cpu(cpu) {
 158                 int nid = cpu_to_node(cpu);
 159                 int bid = uv_cpu_to_blade_id(cpu);
 160                 int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 161                 struct uv_rtc_timer_head *head = blade_info[bid];
 162
 163                 if (!head) {
 164                         head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
 165                                 (uv_blade_nr_possible_cpus(bid) *
 166                                         2 * sizeof(u64)),
 167                                 GFP_KERNEL, nid);
 168                         if (!head) {
 169                                 uv_rtc_deallocate_timers();
 170                                 return -ENOMEM;
 171                         }
 172                         spin_lock_init(&head->lock);
 173                         head->ncpus = uv_blade_nr_possible_cpus(bid);
 174                         head->next_cpu = -1;
 175                         blade_info[bid] = head;
 176                 }
 177
 178                 head->cpu[bcpu].lcpu = cpu;
 179                 head->cpu[bcpu].expires = ULLONG_MAX;
 180         }
 181
 182         return 0;
 183 }
 184
 185 /* Find and set the next expiring timer.  */
 186 static void uv_rtc_find_next_timer(struct uv_rtc_timer_head *head, int pnode)
 187 {
 188         u64 lowest = ULLONG_MAX;
 189         int c, bcpu = -1;
 190
 191         head->next_cpu = -1;
 192         for (c = 0; c < head->ncpus; c++) {
 193                 u64 exp = head->cpu[c].expires;
 194                 if (exp < lowest) {
 195                         bcpu = c;
 196                         lowest = exp;
 197                 }
 198         }
 199         if (bcpu >= 0) {
 200                 head->next_cpu = bcpu;
 201                 c = head->cpu[bcpu].lcpu;
 202                 if (uv_setup_intr(c, lowest))
 203                         /* If we didn't set it up in time, trigger */
 204                         uv_rtc_send_IPI(c);
 205         } else {
 206                 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 207                         UVH_RTC1_INT_CONFIG_M_MASK);
 208         }
 209 }
 210
 211 /*
 212  * Set expiration time for current cpu.
 213  *
 214  * Returns 1 if we missed the expiration time.
 215  */
 216 static int uv_rtc_set_timer(int cpu, u64 expires)
 217 {
 218         int pnode = uv_cpu_to_pnode(cpu);
 219         int bid = uv_cpu_to_blade_id(cpu);
 220         struct uv_rtc_timer_head *head = blade_info[bid];
 221         int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 222         u64 *t = &head->cpu[bcpu].expires;
 223         unsigned long flags;
 224         int next_cpu;
 225
 226         spin_lock_irqsave(&head->lock, flags);
 227
 228         next_cpu = head->next_cpu;
 229         *t = expires;
 230
 231         /* Will this one be next to go off? */
 232         if (next_cpu < 0 || bcpu == next_cpu ||
 233                         expires < head->cpu[next_cpu].expires) {
 234                 head->next_cpu = bcpu;
 235                 if (uv_setup_intr(cpu, expires)) {
 236                         *t = ULLONG_MAX;
 237                         uv_rtc_find_next_timer(head, pnode);
 238                         spin_unlock_irqrestore(&head->lock, flags);
 239                         return -ETIME;
 240                 }
 241         }
 242
 243         spin_unlock_irqrestore(&head->lock, flags);
 244         return 0;
 245 }
 246
 247 /*
 248  * Unset expiration time for current cpu.
 249  *
 250  * Returns 1 if this timer was pending.
 251  */
 252 static int uv_rtc_unset_timer(int cpu, int force)
 253 {
 254         int pnode = uv_cpu_to_pnode(cpu);
 255         int bid = uv_cpu_to_blade_id(cpu);
 256         struct uv_rtc_timer_head *head = blade_info[bid];
 257         int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 258         u64 *t = &head->cpu[bcpu].expires;
 259         unsigned long flags;
 260         int rc = 0;
 261
 262         spin_lock_irqsave(&head->lock, flags);
 263
 264         if ((head->next_cpu == bcpu && uv_read_rtc(NULL) >= *t) || force)
 265                 rc = 1;
 266
 267         if (rc) {
 268                 *t = ULLONG_MAX;
 269                 /* Was the hardware setup for this timer? */
 270                 if (head->next_cpu == bcpu)
 271                         uv_rtc_find_next_timer(head, pnode);
 272         }
 273
 274         spin_unlock_irqrestore(&head->lock, flags);
 275
 276         return rc;
 277 }
 278
 279
 280 /*
 281  * Kernel interface routines.
 282  */
 283
 284 /*
 285  * Read the RTC.
 286  *
 287  * Starting with HUB rev 2.0, the UV RTC register is replicated across all
 288  * cachelines of it's own page.  This allows faster simultaneous reads
 289  * from a given socket.
 290  */
 291 static cycle_t uv_read_rtc(struct clocksource *cs)
 292 {
 293         unsigned long offset;
 294
 295         if (uv_get_min_hub_revision_id() == 1)
 296                 offset = 0;
 297         else
 298                 offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
 299
 300         return (cycle_t)uv_read_local_mmr(UVH_RTC | offset);
 301 }
 302
 303 /*
 304  * Program the next event, relative to now
 305  */
 306 static int uv_rtc_next_event(unsigned long delta,
 307                              struct clock_event_device *ced)
 308 {
 309         int ced_cpu = cpumask_first(ced->cpumask);
 310
 311         return uv_rtc_set_timer(ced_cpu, delta + uv_read_rtc(NULL));
 312 }
 313
 314 /*
 315  * Setup the RTC timer in oneshot mode
 316  */
 317 static void uv_rtc_timer_setup(enum clock_event_mode mode,
 318                                struct clock_event_device *evt)
 319 {
 320         int ced_cpu = cpumask_first(evt->cpumask);
 321
 322         switch (mode) {
 323         case CLOCK_EVT_MODE_PERIODIC:
 324         case CLOCK_EVT_MODE_ONESHOT:
 325         case CLOCK_EVT_MODE_RESUME:
 326                 /* Nothing to do here yet */
 327                 break;
 328         case CLOCK_EVT_MODE_UNUSED:
 329         case CLOCK_EVT_MODE_SHUTDOWN:
 330                 uv_rtc_unset_timer(ced_cpu, 1);
 331                 break;
 332         }
 333 }
 334
 335 static void uv_rtc_interrupt(void)
 336 {
 337         int cpu = smp_processor_id();
 338         struct clock_event_device *ced = &per_cpu(cpu_ced, cpu);
 339
 340         if (!ced || !ced->event_handler)
 341                 return;
 342
 343         if (uv_rtc_unset_timer(cpu, 0) != 1)
 344                 return;
 345
 346         ced->event_handler(ced);
 347 }
 348
 349 static int __init uv_enable_evt_rtc(char *str)
 350 {
 351         uv_rtc_evt_enable = 1;
 352
 353         return 1;
 354 }
 355 __setup("uvrtcevt", uv_enable_evt_rtc);
 356
 357 static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
 358 {
 359         struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
 360
 361         *ced = clock_event_device_uv;
 362         ced->cpumask = cpumask_of(smp_processor_id());
 363         clockevents_register_device(ced);
 364 }
 365
 366 static __init int uv_rtc_setup_clock(void)
 367 {
 368         int rc;
 369
 370         if (!is_uv_system())
 371                 return -ENODEV;
 372
 373         clocksource_uv.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
 374                                 clocksource_uv.shift);
 375
 376         /* If single blade, prefer tsc */
 377         if (uv_num_possible_blades() == 1)
 378                 clocksource_uv.rating = 250;
 379
 380         rc = clocksource_register(&clocksource_uv);
 381         if (rc)
 382                 printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
 383         else
 384                 printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
 385                         sn_rtc_cycles_per_second/(unsigned long)1E6);
 386
 387         if (rc || !uv_rtc_evt_enable || x86_platform_ipi_callback)
 388                 return rc;
 389
 390         /* Setup and register clockevents */
 391         rc = uv_rtc_allocate_timers();
 392         if (rc)
 393                 goto error;
 394
 395         x86_platform_ipi_callback = uv_rtc_interrupt;
 396
 397         clock_event_device_uv.mult = div_sc(sn_rtc_cycles_per_second,
 398                                 NSEC_PER_SEC, clock_event_device_uv.shift);
 399
 400         clock_event_device_uv.min_delta_ns = NSEC_PER_SEC /
 401                                                 sn_rtc_cycles_per_second;
 402
 403         clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
 404                                 (NSEC_PER_SEC / sn_rtc_cycles_per_second);
 405
 406         rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
 407         if (rc) {
 408                 x86_platform_ipi_callback = NULL;
 409                 uv_rtc_deallocate_timers();
 410                 goto error;
 411         }
 412
 413         printk(KERN_INFO "UV RTC clockevents registered\n");
 414
 415         return 0;
 416
 417 error:
 418         clocksource_unregister(&clocksource_uv);
 419         printk(KERN_INFO "UV RTC clockevents failed rc %d\n", rc);
 420
 421         return rc;
 422 }
 423 arch_initcall(uv_rtc_setup_clock);