root/arch/x86/platform/uv/uv_time.c

DEFINITIONS

1. uv_rtc_send_IPI
2. uv_intr_pending
3. uv_setup_intr
4. uv_rtc_deallocate_timers
5. uv_rtc_allocate_timers
6. uv_rtc_find_next_timer
7. uv_rtc_set_timer
8. uv_rtc_unset_timer
9. uv_read_rtc
10. uv_rtc_next_event
11. uv_rtc_shutdown
12. uv_rtc_interrupt
13. uv_enable_evt_rtc
14. uv_rtc_register_clockevents
15. uv_rtc_setup_clock

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * SGI RTC clock/timer routines.
   4  *
   5  *  Copyright (c) 2009-2013 Silicon Graphics, Inc.  All Rights Reserved.
   6  *  Copyright (c) Dimitri Sivanich
   7  */
   8 #include <linux/clockchips.h>
   9 #include <linux/slab.h>
  10 
  11 #include <asm/uv/uv_mmrs.h>
  12 #include <asm/uv/uv_hub.h>
  13 #include <asm/uv/bios.h>
  14 #include <asm/uv/uv.h>
  15 #include <asm/apic.h>
  16 #include <asm/cpu.h>
  17 
  18 #define RTC_NAME                "sgi_rtc"
  19 
  20 static u64 uv_read_rtc(struct clocksource *cs);
  21 static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
  22 static int uv_rtc_shutdown(struct clock_event_device *evt);
  23 
  24 static struct clocksource clocksource_uv = {
  25         .name           = RTC_NAME,
  26         .rating         = 299,
  27         .read           = uv_read_rtc,
  28         .mask           = (u64)UVH_RTC_REAL_TIME_CLOCK_MASK,
  29         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  30 };
  31 
  32 static struct clock_event_device clock_event_device_uv = {
  33         .name                   = RTC_NAME,
  34         .features               = CLOCK_EVT_FEAT_ONESHOT,
  35         .shift                  = 20,
  36         .rating                 = 400,
  37         .irq                    = -1,
  38         .set_next_event         = uv_rtc_next_event,
  39         .set_state_shutdown     = uv_rtc_shutdown,
  40         .event_handler          = NULL,
  41 };
  42 
  43 static DEFINE_PER_CPU(struct clock_event_device, cpu_ced);
  44 
  45 /* There is one of these allocated per node */
  46 struct uv_rtc_timer_head {
  47         spinlock_t      lock;
  48         /* next cpu waiting for timer, local node relative: */
  49         int             next_cpu;
  50         /* number of cpus on this node: */
  51         int             ncpus;
  52         struct {
  53                 int     lcpu;           /* systemwide logical cpu number */
  54                 u64     expires;        /* next timer expiration for this cpu */
  55         } cpu[1];
  56 };
  57 
  58 /*
  59  * Access to uv_rtc_timer_head via blade id.
  60  */
  61 static struct uv_rtc_timer_head         **blade_info __read_mostly;
  62 
  63 static int                              uv_rtc_evt_enable;
  64 
  65 /*
  66  * Hardware interface routines
  67  */
  68 
  69 /* Send IPIs to another node */
  70 static void uv_rtc_send_IPI(int cpu)
  71 {
  72         unsigned long apicid, val;
  73         int pnode;
  74 
  75         apicid = cpu_physical_id(cpu);
  76         pnode = uv_apicid_to_pnode(apicid);
  77         apicid |= uv_apicid_hibits;
  78         val = (1UL << UVH_IPI_INT_SEND_SHFT) |
  79               (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
  80               (X86_PLATFORM_IPI_VECTOR << UVH_IPI_INT_VECTOR_SHFT);
  81 
  82         uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
  83 }
  84 
  85 /* Check for an RTC interrupt pending */
  86 static int uv_intr_pending(int pnode)
  87 {
  88         if (is_uv1_hub())
  89                 return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED0) &
  90                         UV1H_EVENT_OCCURRED0_RTC1_MASK;
  91         else if (is_uvx_hub())
  92                 return uv_read_global_mmr64(pnode, UVXH_EVENT_OCCURRED2) &
  93                         UVXH_EVENT_OCCURRED2_RTC_1_MASK;
  94         return 0;
  95 }
  96 
  97 /* Setup interrupt and return non-zero if early expiration occurred. */
  98 static int uv_setup_intr(int cpu, u64 expires)
  99 {
 100         u64 val;
 101         unsigned long apicid = cpu_physical_id(cpu) | uv_apicid_hibits;
 102         int pnode = uv_cpu_to_pnode(cpu);
 103 
 104         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 105                 UVH_RTC1_INT_CONFIG_M_MASK);
 106         uv_write_global_mmr64(pnode, UVH_INT_CMPB, -1L);
 107 
 108         if (is_uv1_hub())
 109                 uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED0_ALIAS,
 110                                 UV1H_EVENT_OCCURRED0_RTC1_MASK);
 111         else
 112                 uv_write_global_mmr64(pnode, UVXH_EVENT_OCCURRED2_ALIAS,
 113                                 UVXH_EVENT_OCCURRED2_RTC_1_MASK);
 114 
 115         val = (X86_PLATFORM_IPI_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
 116                 ((u64)apicid << UVH_RTC1_INT_CONFIG_APIC_ID_SHFT);
 117 
 118         /* Set configuration */
 119         uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG, val);
 120         /* Initialize comparator value */
 121         uv_write_global_mmr64(pnode, UVH_INT_CMPB, expires);
 122 
 123         if (uv_read_rtc(NULL) <= expires)
 124                 return 0;
 125 
 126         return !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 = kcalloc(uv_possible_blades, sizeof(void *), GFP_KERNEL);
 149         if (!blade_info)
 150                 return -ENOMEM;
 151 
 152         for_each_present_cpu(cpu) {
 153                 int nid = cpu_to_node(cpu);
 154                 int bid = uv_cpu_to_blade_id(cpu);
 155                 int bcpu = uv_cpu_blade_processor_id(cpu);
 156                 struct uv_rtc_timer_head *head = blade_info[bid];
 157 
 158                 if (!head) {
 159                         head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
 160                                 (uv_blade_nr_possible_cpus(bid) *
 161                                         2 * sizeof(u64)),
 162                                 GFP_KERNEL, nid);
 163                         if (!head) {
 164                                 uv_rtc_deallocate_timers();
 165                                 return -ENOMEM;
 166                         }
 167                         spin_lock_init(&head->lock);
 168                         head->ncpus = uv_blade_nr_possible_cpus(bid);
 169                         head->next_cpu = -1;
 170                         blade_info[bid] = head;
 171                 }
 172 
 173                 head->cpu[bcpu].lcpu = cpu;
 174                 head->cpu[bcpu].expires = ULLONG_MAX;
 175         }
 176 
 177         return 0;
 178 }
 179 
 180 /* Find and set the next expiring timer.  */
 181 static void uv_rtc_find_next_timer(struct uv_rtc_timer_head *head, int pnode)
 182 {
 183         u64 lowest = ULLONG_MAX;
 184         int c, bcpu = -1;
 185 
 186         head->next_cpu = -1;
 187         for (c = 0; c < head->ncpus; c++) {
 188                 u64 exp = head->cpu[c].expires;
 189                 if (exp < lowest) {
 190                         bcpu = c;
 191                         lowest = exp;
 192                 }
 193         }
 194         if (bcpu >= 0) {
 195                 head->next_cpu = bcpu;
 196                 c = head->cpu[bcpu].lcpu;
 197                 if (uv_setup_intr(c, lowest))
 198                         /* If we didn't set it up in time, trigger */
 199                         uv_rtc_send_IPI(c);
 200         } else {
 201                 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
 202                         UVH_RTC1_INT_CONFIG_M_MASK);
 203         }
 204 }
 205 
 206 /*
 207  * Set expiration time for current cpu.
 208  *
 209  * Returns 1 if we missed the expiration time.
 210  */
 211 static int uv_rtc_set_timer(int cpu, u64 expires)
 212 {
 213         int pnode = uv_cpu_to_pnode(cpu);
 214         int bid = uv_cpu_to_blade_id(cpu);
 215         struct uv_rtc_timer_head *head = blade_info[bid];
 216         int bcpu = uv_cpu_blade_processor_id(cpu);
 217         u64 *t = &head->cpu[bcpu].expires;
 218         unsigned long flags;
 219         int next_cpu;
 220 
 221         spin_lock_irqsave(&head->lock, flags);
 222 
 223         next_cpu = head->next_cpu;
 224         *t = expires;
 225 
 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 -ETIME;
 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, int force)
 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_blade_processor_id(cpu);
 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(NULL) >= *t) || force)
 260                 rc = 1;
 261 
 262         if (rc) {
 263                 *t = ULLONG_MAX;
 264                 /* Was the hardware setup for this timer? */
 265                 if (head->next_cpu == bcpu)
 266                         uv_rtc_find_next_timer(head, pnode);
 267         }
 268 
 269         spin_unlock_irqrestore(&head->lock, flags);
 270 
 271         return rc;
 272 }
 273 
 274 
 275 /*
 276  * Kernel interface routines.
 277  */
 278 
 279 /*
 280  * Read the RTC.
 281  *
 282  * Starting with HUB rev 2.0, the UV RTC register is replicated across all
 283  * cachelines of it's own page.  This allows faster simultaneous reads
 284  * from a given socket.
 285  */
 286 static u64 uv_read_rtc(struct clocksource *cs)
 287 {
 288         unsigned long offset;
 289 
 290         if (uv_get_min_hub_revision_id() == 1)
 291                 offset = 0;
 292         else
 293                 offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
 294 
 295         return (u64)uv_read_local_mmr(UVH_RTC | offset);
 296 }
 297 
 298 /*
 299  * Program the next event, relative to now
 300  */
 301 static int uv_rtc_next_event(unsigned long delta,
 302                              struct clock_event_device *ced)
 303 {
 304         int ced_cpu = cpumask_first(ced->cpumask);
 305 
 306         return uv_rtc_set_timer(ced_cpu, delta + uv_read_rtc(NULL));
 307 }
 308 
 309 /*
 310  * Shutdown the RTC timer
 311  */
 312 static int uv_rtc_shutdown(struct clock_event_device *evt)
 313 {
 314         int ced_cpu = cpumask_first(evt->cpumask);
 315 
 316         uv_rtc_unset_timer(ced_cpu, 1);
 317         return 0;
 318 }
 319 
 320 static void uv_rtc_interrupt(void)
 321 {
 322         int cpu = smp_processor_id();
 323         struct clock_event_device *ced = &per_cpu(cpu_ced, cpu);
 324 
 325         if (!ced || !ced->event_handler)
 326                 return;
 327 
 328         if (uv_rtc_unset_timer(cpu, 0) != 1)
 329                 return;
 330 
 331         ced->event_handler(ced);
 332 }
 333 
 334 static int __init uv_enable_evt_rtc(char *str)
 335 {
 336         uv_rtc_evt_enable = 1;
 337 
 338         return 1;
 339 }
 340 __setup("uvrtcevt", uv_enable_evt_rtc);
 341 
 342 static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
 343 {
 344         struct clock_event_device *ced = this_cpu_ptr(&cpu_ced);
 345 
 346         *ced = clock_event_device_uv;
 347         ced->cpumask = cpumask_of(smp_processor_id());
 348         clockevents_register_device(ced);
 349 }
 350 
 351 static __init int uv_rtc_setup_clock(void)
 352 {
 353         int rc;
 354 
 355         if (!is_uv_system())
 356                 return -ENODEV;
 357 
 358         rc = clocksource_register_hz(&clocksource_uv, sn_rtc_cycles_per_second);
 359         if (rc)
 360                 printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
 361         else
 362                 printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
 363                         sn_rtc_cycles_per_second/(unsigned long)1E6);
 364 
 365         if (rc || !uv_rtc_evt_enable || x86_platform_ipi_callback)
 366                 return rc;
 367 
 368         /* Setup and register clockevents */
 369         rc = uv_rtc_allocate_timers();
 370         if (rc)
 371                 goto error;
 372 
 373         x86_platform_ipi_callback = uv_rtc_interrupt;
 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         clock_event_device_uv.min_delta_ticks = 1;
 381 
 382         clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
 383                                 (NSEC_PER_SEC / sn_rtc_cycles_per_second);
 384         clock_event_device_uv.max_delta_ticks = clocksource_uv.mask;
 385 
 386         rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
 387         if (rc) {
 388                 x86_platform_ipi_callback = NULL;
 389                 uv_rtc_deallocate_timers();
 390                 goto error;
 391         }
 392 
 393         printk(KERN_INFO "UV RTC clockevents registered\n");
 394 
 395         return 0;
 396 
 397 error:
 398         clocksource_unregister(&clocksource_uv);
 399         printk(KERN_INFO "UV RTC clockevents failed rc %d\n", rc);
 400 
 401         return rc;
 402 }
 403 arch_initcall(uv_rtc_setup_clock);