arch/arm/kernel/arch_timer.c

   1 /*
   2  *  linux/arch/arm/kernel/arch_timer.c
   3  *
   4  *  Copyright (C) 2011 ARM Ltd.
   5  *  All Rights Reserved
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/delay.h>
  14 #include <linux/device.h>
  15 #include <linux/smp.h>
  16 #include <linux/cpu.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/of_irq.h>
  21 #include <linux/io.h>
  22
  23 #include <asm/cputype.h>
  24 #include <asm/delay.h>
  25 #include <asm/localtimer.h>
  26 #include <asm/arch_timer.h>
  27 #include <asm/system_info.h>
  28 #include <asm/sched_clock.h>
  29
  30 static unsigned long arch_timer_rate;
  31
  32 enum ppi_nr {
  33         PHYS_SECURE_PPI,
  34         PHYS_NONSECURE_PPI,
  35         VIRT_PPI,
  36         HYP_PPI,
  37         MAX_TIMER_PPI
  38 };
  39
  40 static int arch_timer_ppi[MAX_TIMER_PPI];
  41
  42 static struct clock_event_device __percpu **arch_timer_evt;
  43 static struct delay_timer arch_delay_timer;
  44
  45 static bool arch_timer_use_virtual = true;
  46
  47 /*
  48  * Architected system timer support.
  49  */
  50
  51 #define ARCH_TIMER_CTRL_ENABLE          (1 << 0)
  52 #define ARCH_TIMER_CTRL_IT_MASK         (1 << 1)
  53 #define ARCH_TIMER_CTRL_IT_STAT         (1 << 2)
  54
  55 #define ARCH_TIMER_REG_CTRL             0
  56 #define ARCH_TIMER_REG_FREQ             1
  57 #define ARCH_TIMER_REG_TVAL             2
  58
  59 #define ARCH_TIMER_PHYS_ACCESS          0
  60 #define ARCH_TIMER_VIRT_ACCESS          1
  61
  62 /*
  63  * These register accessors are marked inline so the compiler can
  64  * nicely work out which register we want, and chuck away the rest of
  65  * the code. At least it does so with a recent GCC (4.6.3).
  66  */
  67 static inline void arch_timer_reg_write(const int access, const int reg, u32 val)
  68 {
  69         if (access == ARCH_TIMER_PHYS_ACCESS) {
  70                 switch (reg) {
  71                 case ARCH_TIMER_REG_CTRL:
  72                         asm volatile("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
  73                         break;
  74                 case ARCH_TIMER_REG_TVAL:
  75                         asm volatile("mcr p15, 0, %0, c14, c2, 0" : : "r" (val));
  76                         break;
  77                 }
  78         }
  79
  80         if (access == ARCH_TIMER_VIRT_ACCESS) {
  81                 switch (reg) {
  82                 case ARCH_TIMER_REG_CTRL:
  83                         asm volatile("mcr p15, 0, %0, c14, c3, 1" : : "r" (val));
  84                         break;
  85                 case ARCH_TIMER_REG_TVAL:
  86                         asm volatile("mcr p15, 0, %0, c14, c3, 0" : : "r" (val));
  87                         break;
  88                 }
  89         }
  90
  91         isb();
  92 }
  93
  94 static inline u32 arch_timer_reg_read(const int access, const int reg)
  95 {
  96         u32 val = 0;
  97
  98         if (access == ARCH_TIMER_PHYS_ACCESS) {
  99                 switch (reg) {
 100                 case ARCH_TIMER_REG_CTRL:
 101                         asm volatile("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
 102                         break;
 103                 case ARCH_TIMER_REG_TVAL:
 104                         asm volatile("mrc p15, 0, %0, c14, c2, 0" : "=r" (val));
 105                         break;
 106                 case ARCH_TIMER_REG_FREQ:
 107                         asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (val));
 108                         break;
 109                 }
 110         }
 111
 112         if (access == ARCH_TIMER_VIRT_ACCESS) {
 113                 switch (reg) {
 114                 case ARCH_TIMER_REG_CTRL:
 115                         asm volatile("mrc p15, 0, %0, c14, c3, 1" : "=r" (val));
 116                         break;
 117                 case ARCH_TIMER_REG_TVAL:
 118                         asm volatile("mrc p15, 0, %0, c14, c3, 0" : "=r" (val));
 119                         break;
 120                 }
 121         }
 122
 123         return val;
 124 }
 125
 126 static inline cycle_t arch_timer_counter_read(const int access)
 127 {
 128         cycle_t cval = 0;
 129
 130         if (access == ARCH_TIMER_PHYS_ACCESS)
 131                 asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval));
 132
 133         if (access == ARCH_TIMER_VIRT_ACCESS)
 134                 asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (cval));
 135
 136         return cval;
 137 }
 138
 139 static inline cycle_t arch_counter_get_cntpct(void)
 140 {
 141         return arch_timer_counter_read(ARCH_TIMER_PHYS_ACCESS);
 142 }
 143
 144 static inline cycle_t arch_counter_get_cntvct(void)
 145 {
 146         return arch_timer_counter_read(ARCH_TIMER_VIRT_ACCESS);
 147 }
 148
 149 static irqreturn_t inline timer_handler(const int access,
 150                                         struct clock_event_device *evt)
 151 {
 152         unsigned long ctrl;
 153         ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 154         if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
 155                 ctrl |= ARCH_TIMER_CTRL_IT_MASK;
 156                 arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 157                 evt->event_handler(evt);
 158                 return IRQ_HANDLED;
 159         }
 160
 161         return IRQ_NONE;
 162 }
 163
 164 static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
 165 {
 166         struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
 167
 168         return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
 169 }
 170
 171 static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
 172 {
 173         struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
 174
 175         return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
 176 }
 177
 178 static inline void timer_set_mode(const int access, int mode)
 179 {
 180         unsigned long ctrl;
 181         switch (mode) {
 182         case CLOCK_EVT_MODE_UNUSED:
 183         case CLOCK_EVT_MODE_SHUTDOWN:
 184                 ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 185                 ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
 186                 arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 187                 break;
 188         default:
 189                 break;
 190         }
 191 }
 192
 193 static void arch_timer_set_mode_virt(enum clock_event_mode mode,
 194                                      struct clock_event_device *clk)
 195 {
 196         timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
 197 }
 198
 199 static void arch_timer_set_mode_phys(enum clock_event_mode mode,
 200                                      struct clock_event_device *clk)
 201 {
 202         timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
 203 }
 204
 205 static inline void set_next_event(const int access, unsigned long evt)
 206 {
 207         unsigned long ctrl;
 208         ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 209         ctrl |= ARCH_TIMER_CTRL_ENABLE;
 210         ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 211         arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
 212         arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 213 }
 214
 215 static int arch_timer_set_next_event_virt(unsigned long evt,
 216                                           struct clock_event_device *unused)
 217 {
 218         set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
 219         return 0;
 220 }
 221
 222 static int arch_timer_set_next_event_phys(unsigned long evt,
 223                                           struct clock_event_device *unused)
 224 {
 225         set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
 226         return 0;
 227 }
 228
 229 static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
 230 {
 231         clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
 232         clk->name = "arch_sys_timer";
 233         clk->rating = 450;
 234         if (arch_timer_use_virtual) {
 235                 clk->irq = arch_timer_ppi[VIRT_PPI];
 236                 clk->set_mode = arch_timer_set_mode_virt;
 237                 clk->set_next_event = arch_timer_set_next_event_virt;
 238         } else {
 239                 clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
 240                 clk->set_mode = arch_timer_set_mode_phys;
 241                 clk->set_next_event = arch_timer_set_next_event_phys;
 242         }
 243
 244         clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);
 245
 246         clockevents_config_and_register(clk, arch_timer_rate,
 247                                         0xf, 0x7fffffff);
 248
 249         *__this_cpu_ptr(arch_timer_evt) = clk;
 250
 251         if (arch_timer_use_virtual)
 252                 enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
 253         else {
 254                 enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
 255                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 256                         enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
 257         }
 258
 259         return 0;
 260 }
 261
 262 /* Is the optional system timer available? */
 263 static int local_timer_is_architected(void)
 264 {
 265         return (cpu_architecture() >= CPU_ARCH_ARMv7) &&
 266                ((read_cpuid_ext(CPUID_EXT_PFR1) >> 16) & 0xf) == 1;
 267 }
 268
 269 static int arch_timer_available(void)
 270 {
 271         unsigned long freq;
 272
 273         if (!local_timer_is_architected())
 274                 return -ENXIO;
 275
 276         if (arch_timer_rate == 0) {
 277                 freq = arch_timer_reg_read(ARCH_TIMER_PHYS_ACCESS,
 278                                            ARCH_TIMER_REG_FREQ);
 279
 280                 /* Check the timer frequency. */
 281                 if (freq == 0) {
 282                         pr_warn("Architected timer frequency not available\n");
 283                         return -EINVAL;
 284                 }
 285
 286                 arch_timer_rate = freq;
 287         }
 288
 289         pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
 290                      arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100,
 291                      arch_timer_use_virtual ? "virt" : "phys");
 292         return 0;
 293 }
 294
 295 static u32 notrace arch_counter_get_cntpct32(void)
 296 {
 297         cycle_t cnt = arch_counter_get_cntpct();
 298
 299         /*
 300          * The sched_clock infrastructure only knows about counters
 301          * with at most 32bits. Forget about the upper 24 bits for the
 302          * time being...
 303          */
 304         return (u32)cnt;
 305 }
 306
 307 static u32 notrace arch_counter_get_cntvct32(void)
 308 {
 309         cycle_t cnt = arch_counter_get_cntvct();
 310
 311         /*
 312          * The sched_clock infrastructure only knows about counters
 313          * with at most 32bits. Forget about the upper 24 bits for the
 314          * time being...
 315          */
 316         return (u32)cnt;
 317 }
 318
 319 static cycle_t arch_counter_read(struct clocksource *cs)
 320 {
 321         /*
 322          * Always use the physical counter for the clocksource.
 323          * CNTHCTL.PL1PCTEN must be set to 1.
 324          */
 325         return arch_counter_get_cntpct();
 326 }
 327
 328 static unsigned long arch_timer_read_current_timer(void)
 329 {
 330         return arch_counter_get_cntpct();
 331 }
 332
 333 static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
 334 {
 335         /*
 336          * Always use the physical counter for the clocksource.
 337          * CNTHCTL.PL1PCTEN must be set to 1.
 338          */
 339         return arch_counter_get_cntpct();
 340 }
 341
 342 static struct clocksource clocksource_counter = {
 343         .name   = "arch_sys_counter",
 344         .rating = 400,
 345         .read   = arch_counter_read,
 346         .mask   = CLOCKSOURCE_MASK(56),
 347         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 348 };
 349
 350 static struct cyclecounter cyclecounter = {
 351         .read   = arch_counter_read_cc,
 352         .mask   = CLOCKSOURCE_MASK(56),
 353 };
 354
 355 static struct timecounter timecounter;
 356
 357 struct timecounter *arch_timer_get_timecounter(void)
 358 {
 359         return &timecounter;
 360 }
 361
 362 static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
 363 {
 364         pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
 365                  clk->irq, smp_processor_id());
 366
 367         if (arch_timer_use_virtual)
 368                 disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
 369         else {
 370                 disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
 371                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 372                         disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
 373         }
 374
 375         clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
 376 }
 377
 378 static struct local_timer_ops arch_timer_ops __cpuinitdata = {
 379         .setup  = arch_timer_setup,
 380         .stop   = arch_timer_stop,
 381 };
 382
 383 static struct clock_event_device arch_timer_global_evt;
 384
 385 static int __init arch_timer_register(void)
 386 {
 387         int err;
 388         int ppi;
 389
 390         err = arch_timer_available();
 391         if (err)
 392                 goto out;
 393
 394         arch_timer_evt = alloc_percpu(struct clock_event_device *);
 395         if (!arch_timer_evt) {
 396                 err = -ENOMEM;
 397                 goto out;
 398         }
 399
 400         clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 401         cyclecounter.mult = clocksource_counter.mult;
 402         cyclecounter.shift = clocksource_counter.shift;
 403         timecounter_init(&timecounter, &cyclecounter,
 404                          arch_counter_get_cntpct());
 405
 406         if (arch_timer_use_virtual) {
 407                 ppi = arch_timer_ppi[VIRT_PPI];
 408                 err = request_percpu_irq(ppi, arch_timer_handler_virt,
 409                                          "arch_timer", arch_timer_evt);
 410         } else {
 411                 ppi = arch_timer_ppi[PHYS_SECURE_PPI];
 412                 err = request_percpu_irq(ppi, arch_timer_handler_phys,
 413                                          "arch_timer", arch_timer_evt);
 414                 if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 415                         ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
 416                         err = request_percpu_irq(ppi, arch_timer_handler_phys,
 417                                                  "arch_timer", arch_timer_evt);
 418                         if (err)
 419                                 free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 420                                                 arch_timer_evt);
 421                 }
 422         }
 423
 424         if (err) {
 425                 pr_err("arch_timer: can't register interrupt %d (%d)\n",
 426                        ppi, err);
 427                 goto out_free;
 428         }
 429
 430         err = local_timer_register(&arch_timer_ops);
 431         if (err) {
 432                 /*
 433                  * We couldn't register as a local timer (could be
 434                  * because we're on a UP platform, or because some
 435                  * other local timer is already present...). Try as a
 436                  * global timer instead.
 437                  */
 438                 arch_timer_global_evt.cpumask = cpumask_of(0);
 439                 err = arch_timer_setup(&arch_timer_global_evt);
 440         }
 441         if (err)
 442                 goto out_free_irq;
 443
 444         /* Use the architected timer for the delay loop. */
 445         arch_delay_timer.read_current_timer = &arch_timer_read_current_timer;
 446         arch_delay_timer.freq = arch_timer_rate;
 447         register_current_timer_delay(&arch_delay_timer);
 448         return 0;
 449
 450 out_free_irq:
 451         if (arch_timer_use_virtual)
 452                 free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
 453         else {
 454                 free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 455                                 arch_timer_evt);
 456                 if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 457                         free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
 458                                         arch_timer_evt);
 459         }
 460
 461 out_free:
 462         free_percpu(arch_timer_evt);
 463 out:
 464         return err;
 465 }
 466
 467 static const struct of_device_id arch_timer_of_match[] __initconst = {
 468         { .compatible   = "arm,armv7-timer",    },
 469         {},
 470 };
 471
 472 int __init arch_timer_of_register(void)
 473 {
 474         struct device_node *np;
 475         u32 freq;
 476         int i;
 477
 478         np = of_find_matching_node(NULL, arch_timer_of_match);
 479         if (!np) {
 480                 pr_err("arch_timer: can't find DT node\n");
 481                 return -ENODEV;
 482         }
 483
 484         /* Try to determine the frequency from the device tree or CNTFRQ */
 485         if (!of_property_read_u32(np, "clock-frequency", &freq))
 486                 arch_timer_rate = freq;
 487
 488         for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
 489                 arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
 490
 491         /*
 492          * If no interrupt provided for virtual timer, we'll have to
 493          * stick to the physical timer. It'd better be accessible...
 494          */
 495         if (!arch_timer_ppi[VIRT_PPI]) {
 496                 arch_timer_use_virtual = false;
 497
 498                 if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
 499                     !arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 500                         pr_warn("arch_timer: No interrupt available, giving up\n");
 501                         return -EINVAL;
 502                 }
 503         }
 504
 505         return arch_timer_register();
 506 }
 507
 508 int __init arch_timer_sched_clock_init(void)
 509 {
 510         u32 (*cnt32)(void);
 511         int err;
 512
 513         err = arch_timer_available();
 514         if (err)
 515                 return err;
 516
 517         if (arch_timer_use_virtual)
 518                 cnt32 = arch_counter_get_cntvct32;
 519         else
 520                 cnt32 = arch_counter_get_cntpct32;
 521
 522         setup_sched_clock(cnt32, 32, arch_timer_rate);
 523         return 0;
 524 }