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
  23 #include <asm/uv/uv_mmrs.h>
  24 #include <asm/uv/uv_hub.h>
  25 #include <asm/uv/bios.h>
  26 #include <asm/uv/uv.h>
  27 #include <asm/apic.h>
  28 #include <asm/cpu.h>
  29
  30 #define RTC_NAME                "sgi_rtc"
  31
  32 static cycle_t uv_read_rtc(void);
  33 static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
  34 static void uv_rtc_timer_setup(enum clock_event_mode,
  35                                 struct clock_event_device *);
  36
  37 static struct clocksource clocksource_uv = {
  38         .name           = RTC_NAME,
  39         .rating         = 400,
  40         .read           = uv_read_rtc,
  41         .mask           = (cycle_t)UVH_RTC_REAL_TIME_CLOCK_MASK,
  42         .shift          = 10,
  43         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  44 };
  45
  46 static struct clock_event_device clock_event_device_uv = {
  47         .name           = RTC_NAME,
  48         .features       = CLOCK_EVT_FEAT_ONESHOT,
  49         .shift          = 20,
  50         .rating         = 400,
  51         .irq            = -1,
  52         .set_next_event = uv_rtc_next_event,
  53         .set_mode       = uv_rtc_timer_setup,
  54         .event_handler  = NULL,
  55 };
  56
  57 static DEFINE_PER_CPU(struct clock_event_device, cpu_ced);
  58
  59 /* There is one of these allocated per node */
  60 struct uv_rtc_timer_head {
  61         spinlock_t      lock;
  62         /* next cpu waiting for timer, local node relative: */
  63         int             next_cpu;
  64         /* number of cpus on this node: */
  65         int             ncpus;
  66         struct {
  67                 int     lcpu;           /* systemwide logical cpu number */
  68                 u64     expires;        /* next timer expiration for this cpu */
  69         } cpu[1];
  70 };
  71
  72 /*
  73  * Access to uv_rtc_timer_head via blade id.
  74  */
  75 static struct uv_rtc_timer_head         **blade_info __read_mostly;
  76
  77 static int                              uv_rtc_enable;
  78
  79 /*
  80  * Hardware interface routines
  81  */
  82
  83 /* Send IPIs to another node */
  84 static void uv_rtc_send_IPI(int cpu)
  85 {
  86         unsigned long apicid, val;
  87         int pnode;
  88
  89         apicid = cpu_physical_id(cpu);
  90         pnode = uv_apicid_to_pnode(apicid);
  91         val = (1UL << UVH_IPI_INT_SEND_SHFT) |
  92               (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
  93               (GENERIC_INTERRUPT_VECTOR << UVH_IPI_INT_VECTOR_SHFT);
  94
  95         uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
  96 }
  97
  98 /* Check for an RTC interrupt pending */
  99 static int uv_intr_pending(int pnode)
 100 {
 101         return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED0) &
 102                 UVH_EVENT_OCCURRED0_RTC1_MASK;
 103 }
 104
 105 /* Setup interrupt and return non-zero if early expiration occurred. */
 106 static int uv_setup_intr(int cpu, u64 expires)
 107 {
 108         u64 val;
 109         int pnode = uv_cpu_to_pnode(cpu);
 110
 111         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 112                 UVH_RTC1_INT_CONFIG_M_MASK);
 113         uv_write_global_mmr64(pnode, UVH_INT_CMPB, -1L);
 114
 115         uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED0_ALIAS,
 116                 UVH_EVENT_OCCURRED0_RTC1_MASK);
 117
 118         val = (GENERIC_INTERRUPT_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
 119                 ((u64)cpu_physical_id(cpu) << UVH_RTC1_INT_CONFIG_APIC_ID_SHFT);
 120
 121         /* Set configuration */
 122         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG, val);
 123         /* Initialize comparator value */
 124         uv_write_global_mmr64(pnode, UVH_INT_CMPB, expires);
 125
 126         return (expires < uv_read_rtc() && !uv_intr_pending(pnode));
 127 }
 128
 129 /*
 130  * Per-cpu timer tracking routines
 131  */
 132
 133 static __init void uv_rtc_deallocate_timers(void)
 134 {
 135         int bid;
 136
 137         for_each_possible_blade(bid) {
 138                 kfree(blade_info[bid]);
 139         }
 140         kfree(blade_info);
 141 }
 142
 143 /* Allocate per-node list of cpu timer expiration times. */
 144 static __init int uv_rtc_allocate_timers(void)
 145 {
 146         int cpu;
 147
 148         blade_info = kmalloc(uv_possible_blades * sizeof(void *), GFP_KERNEL);
 149         if (!blade_info)
 150                 return -ENOMEM;
 151         memset(blade_info, 0, uv_possible_blades * sizeof(void *));
 152
 153         for_each_present_cpu(cpu) {
 154                 int nid = cpu_to_node(cpu);
 155                 int bid = uv_cpu_to_blade_id(cpu);
 156                 int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 157                 struct uv_rtc_timer_head *head = blade_info[bid];
 158
 159                 if (!head) {
 160                         head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
 161                                 (uv_blade_nr_possible_cpus(bid) *
 162                                         2 * sizeof(u64)),
 163                                 GFP_KERNEL, nid);
 164                         if (!head) {
 165                                 uv_rtc_deallocate_timers();
 166                                 return -ENOMEM;
 167                         }
 168                         spin_lock_init(&head->lock);
 169                         head->ncpus = uv_blade_nr_possible_cpus(bid);
 170                         head->next_cpu = -1;
 171                         blade_info[bid] = head;
 172                 }
 173
 174                 head->cpu[bcpu].lcpu = cpu;
 175                 head->cpu[bcpu].expires = ULLONG_MAX;
 176         }
 177
 178         return 0;
 179 }
 180
 181 /* Find and set the next expiring timer.  */
 182 static void uv_rtc_find_next_timer(struct uv_rtc_timer_head *head, int pnode)
 183 {
 184         u64 lowest = ULLONG_MAX;
 185         int c, bcpu = -1;
 186
 187         head->next_cpu = -1;
 188         for (c = 0; c < head->ncpus; c++) {
 189                 u64 exp = head->cpu[c].expires;
 190                 if (exp < lowest) {
 191                         bcpu = c;
 192                         lowest = exp;
 193                 }
 194         }
 195         if (bcpu >= 0) {
 196                 head->next_cpu = bcpu;
 197                 c = head->cpu[bcpu].lcpu;
 198                 if (uv_setup_intr(c, lowest))
 199                         /* If we didn't set it up in time, trigger */
 200                         uv_rtc_send_IPI(c);
 201         } else {
 202                 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 203                         UVH_RTC1_INT_CONFIG_M_MASK);
 204         }
 205 }
 206
 207 /*
 208  * Set expiration time for current cpu.
 209  *
 210  * Returns 1 if we missed the expiration time.
 211  */
 212 static int uv_rtc_set_timer(int cpu, u64 expires)
 213 {
 214         int pnode = uv_cpu_to_pnode(cpu);
 215         int bid = uv_cpu_to_blade_id(cpu);
 216         struct uv_rtc_timer_head *head = blade_info[bid];
 217         int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 218         u64 *t = &head->cpu[bcpu].expires;
 219         unsigned long flags;
 220         int next_cpu;
 221
 222         spin_lock_irqsave(&head->lock, flags);
 223
 224         next_cpu = head->next_cpu;
 225         *t = expires;
 226         /* Will this one be next to go off? */
 227         if (next_cpu < 0 || bcpu == next_cpu ||
 228                         expires < head->cpu[next_cpu].expires) {
 229                 head->next_cpu = bcpu;
 230                 if (uv_setup_intr(cpu, expires)) {
 231                         *t = ULLONG_MAX;
 232                         uv_rtc_find_next_timer(head, pnode);
 233                         spin_unlock_irqrestore(&head->lock, flags);
 234                         return 1;
 235                 }
 236         }
 237
 238         spin_unlock_irqrestore(&head->lock, flags);
 239         return 0;
 240 }
 241
 242 /*
 243  * Unset expiration time for current cpu.
 244  *
 245  * Returns 1 if this timer was pending.
 246  */
 247 static int uv_rtc_unset_timer(int cpu)
 248 {
 249         int pnode = uv_cpu_to_pnode(cpu);
 250         int bid = uv_cpu_to_blade_id(cpu);
 251         struct uv_rtc_timer_head *head = blade_info[bid];
 252         int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
 253         u64 *t = &head->cpu[bcpu].expires;
 254         unsigned long flags;
 255         int rc = 0;
 256
 257         spin_lock_irqsave(&head->lock, flags);
 258
 259         if (head->next_cpu == bcpu && uv_read_rtc() >= *t)
 260                 rc = 1;
 261
 262         *t = ULLONG_MAX;
 263
 264         /* Was the hardware setup for this timer? */
 265         if (head->next_cpu == bcpu)
 266                 uv_rtc_find_next_timer(head, pnode);
 267
 268         spin_unlock_irqrestore(&head->lock, flags);
 269
 270         return rc;
 271 }
 272
 273
 274 /*
 275  * Kernel interface routines.
 276  */
 277
 278 /*
 279  * Read the RTC.
 280  */
 281 static cycle_t uv_read_rtc(void)
 282 {
 283         return (cycle_t)uv_read_local_mmr(UVH_RTC);
 284 }
 285
 286 /*
 287  * Program the next event, relative to now
 288  */
 289 static int uv_rtc_next_event(unsigned long delta,
 290                              struct clock_event_device *ced)
 291 {
 292         int ced_cpu = cpumask_first(ced->cpumask);
 293
 294         return uv_rtc_set_timer(ced_cpu, delta + uv_read_rtc());
 295 }
 296
 297 /*
 298  * Setup the RTC timer in oneshot mode
 299  */
 300 static void uv_rtc_timer_setup(enum clock_event_mode mode,
 301                                struct clock_event_device *evt)
 302 {
 303         int ced_cpu = cpumask_first(evt->cpumask);
 304
 305         switch (mode) {
 306         case CLOCK_EVT_MODE_PERIODIC:
 307         case CLOCK_EVT_MODE_ONESHOT:
 308         case CLOCK_EVT_MODE_RESUME:
 309                 /* Nothing to do here yet */
 310                 break;
 311         case CLOCK_EVT_MODE_UNUSED:
 312         case CLOCK_EVT_MODE_SHUTDOWN:
 313                 uv_rtc_unset_timer(ced_cpu);
 314                 break;
 315         }
 316 }
 317
 318 static void uv_rtc_interrupt(void)
 319 {
 320         struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
 321         int cpu = smp_processor_id();
 322
 323         if (!ced || !ced->event_handler)
 324                 return;
 325
 326         if (uv_rtc_unset_timer(cpu) != 1)
 327                 return;
 328
 329         ced->event_handler(ced);
 330 }
 331
 332 static int __init uv_enable_rtc(char *str)
 333 {
 334         uv_rtc_enable = 1;
 335
 336         return 1;
 337 }
 338 __setup("uvrtc", uv_enable_rtc);
 339
 340 static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
 341 {
 342         struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
 343
 344         *ced = clock_event_device_uv;
 345         ced->cpumask = cpumask_of(smp_processor_id());
 346         clockevents_register_device(ced);
 347 }
 348
 349 static __init int uv_rtc_setup_clock(void)
 350 {
 351         int rc;
 352
 353         if (!uv_rtc_enable || !is_uv_system() || generic_interrupt_extension)
 354                 return -ENODEV;
 355
 356         generic_interrupt_extension = uv_rtc_interrupt;
 357
 358         clocksource_uv.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
 359                                 clocksource_uv.shift);
 360
 361         rc = clocksource_register(&clocksource_uv);
 362         if (rc) {
 363                 generic_interrupt_extension = NULL;
 364                 return rc;
 365         }
 366
 367         /* Setup and register clockevents */
 368         rc = uv_rtc_allocate_timers();
 369         if (rc) {
 370                 clocksource_unregister(&clocksource_uv);
 371                 generic_interrupt_extension = NULL;
 372                 return rc;
 373         }
 374
 375         clock_event_device_uv.mult = div_sc(sn_rtc_cycles_per_second,
 376                                 NSEC_PER_SEC, clock_event_device_uv.shift);
 377
 378         clock_event_device_uv.min_delta_ns = NSEC_PER_SEC /
 379                                                 sn_rtc_cycles_per_second;
 380
 381         clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
 382                                 (NSEC_PER_SEC / sn_rtc_cycles_per_second);
 383
 384         rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
 385         if (rc) {
 386                 clocksource_unregister(&clocksource_uv);
 387                 generic_interrupt_extension = NULL;
 388                 uv_rtc_deallocate_timers();
 389         }
 390
 391         return rc;
 392 }
 393 arch_initcall(uv_rtc_setup_clock);