arch/blackfin/kernel/time-ts.c

   1 /*
   2  * Based on arm clockevents implementation and old bfin time tick.
   3  *
   4  * Copyright 2008-2009 Analog Devics Inc.
   5  *                2008 GeoTechnologies
   6  *                     Vitja Makarov
   7  *
   8  * Licensed under the GPL-2
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/profile.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/time.h>
  15 #include <linux/timex.h>
  16 #include <linux/irq.h>
  17 #include <linux/clocksource.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/cpufreq.h>
  20
  21 #include <asm/blackfin.h>
  22 #include <asm/time.h>
  23 #include <asm/gptimers.h>
  24 #include <asm/nmi.h>
  25
  26 /* Accelerators for sched_clock()
  27  * convert from cycles(64bits) => nanoseconds (64bits)
  28  *  basic equation:
  29  *              ns = cycles / (freq / ns_per_sec)
  30  *              ns = cycles * (ns_per_sec / freq)
  31  *              ns = cycles * (10^9 / (cpu_khz * 10^3))
  32  *              ns = cycles * (10^6 / cpu_khz)
  33  *
  34  *      Then we use scaling math (suggested by george@mvista.com) to get:
  35  *              ns = cycles * (10^6 * SC / cpu_khz) / SC
  36  *              ns = cycles * cyc2ns_scale / SC
  37  *
  38  *      And since SC is a constant power of two, we can convert the div
  39  *  into a shift.
  40  *
  41  *  We can use khz divisor instead of mhz to keep a better precision, since
  42  *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
  43  *  (mathieu.desnoyers@polymtl.ca)
  44  *
  45  *                      -johnstul@us.ibm.com "math is hard, lets go shopping!"
  46  */
  47
  48 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
  49
  50 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
  51
  52 static notrace cycle_t bfin_read_cycles(struct clocksource *cs)
  53 {
  54 #ifdef CONFIG_CPU_FREQ
  55         return __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod);
  56 #else
  57         return get_cycles();
  58 #endif
  59 }
  60
  61 static struct clocksource bfin_cs_cycles = {
  62         .name           = "bfin_cs_cycles",
  63         .rating         = 400,
  64         .read           = bfin_read_cycles,
  65         .mask           = CLOCKSOURCE_MASK(64),
  66         .shift          = CYC2NS_SCALE_FACTOR,
  67         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  68 };
  69
  70 static inline unsigned long long bfin_cs_cycles_sched_clock(void)
  71 {
  72         return clocksource_cyc2ns(bfin_read_cycles(&bfin_cs_cycles),
  73                 bfin_cs_cycles.mult, bfin_cs_cycles.shift);
  74 }
  75
  76 static int __init bfin_cs_cycles_init(void)
  77 {
  78         bfin_cs_cycles.mult = \
  79                 clocksource_hz2mult(get_cclk(), bfin_cs_cycles.shift);
  80
  81         if (clocksource_register(&bfin_cs_cycles))
  82                 panic("failed to register clocksource");
  83
  84         return 0;
  85 }
  86 #else
  87 # define bfin_cs_cycles_init()
  88 #endif
  89
  90 #ifdef CONFIG_GPTMR0_CLOCKSOURCE
  91
  92 void __init setup_gptimer0(void)
  93 {
  94         disable_gptimers(TIMER0bit);
  95
  96         set_gptimer_config(TIMER0_id, \
  97                 TIMER_OUT_DIS | TIMER_PERIOD_CNT | TIMER_MODE_PWM);
  98         set_gptimer_period(TIMER0_id, -1);
  99         set_gptimer_pwidth(TIMER0_id, -2);
 100         SSYNC();
 101         enable_gptimers(TIMER0bit);
 102 }
 103
 104 static cycle_t bfin_read_gptimer0(struct clocksource *cs)
 105 {
 106         return bfin_read_TIMER0_COUNTER();
 107 }
 108
 109 static struct clocksource bfin_cs_gptimer0 = {
 110         .name           = "bfin_cs_gptimer0",
 111         .rating         = 350,
 112         .read           = bfin_read_gptimer0,
 113         .mask           = CLOCKSOURCE_MASK(32),
 114         .shift          = CYC2NS_SCALE_FACTOR,
 115         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 116 };
 117
 118 static inline unsigned long long bfin_cs_gptimer0_sched_clock(void)
 119 {
 120         return clocksource_cyc2ns(bfin_read_TIMER0_COUNTER(),
 121                 bfin_cs_gptimer0.mult, bfin_cs_gptimer0.shift);
 122 }
 123
 124 static int __init bfin_cs_gptimer0_init(void)
 125 {
 126         setup_gptimer0();
 127
 128         bfin_cs_gptimer0.mult = \
 129                 clocksource_hz2mult(get_sclk(), bfin_cs_gptimer0.shift);
 130
 131         if (clocksource_register(&bfin_cs_gptimer0))
 132                 panic("failed to register clocksource");
 133
 134         return 0;
 135 }
 136 #else
 137 # define bfin_cs_gptimer0_init()
 138 #endif
 139
 140 #if defined(CONFIG_GPTMR0_CLOCKSOURCE) || defined(CONFIG_CYCLES_CLOCKSOURCE)
 141 /* prefer to use cycles since it has higher rating */
 142 notrace unsigned long long sched_clock(void)
 143 {
 144 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
 145         return bfin_cs_cycles_sched_clock();
 146 #else
 147         return bfin_cs_gptimer0_sched_clock();
 148 #endif
 149 }
 150 #endif
 151
 152 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 153 static int bfin_gptmr0_set_next_event(unsigned long cycles,
 154                                      struct clock_event_device *evt)
 155 {
 156         disable_gptimers(TIMER0bit);
 157
 158         /* it starts counting three SCLK cycles after the TIMENx bit is set */
 159         set_gptimer_pwidth(TIMER0_id, cycles - 3);
 160         enable_gptimers(TIMER0bit);
 161         return 0;
 162 }
 163
 164 static void bfin_gptmr0_set_mode(enum clock_event_mode mode,
 165                                 struct clock_event_device *evt)
 166 {
 167         switch (mode) {
 168         case CLOCK_EVT_MODE_PERIODIC: {
 169                 set_gptimer_config(TIMER0_id, \
 170                         TIMER_OUT_DIS | TIMER_IRQ_ENA | \
 171                         TIMER_PERIOD_CNT | TIMER_MODE_PWM);
 172                 set_gptimer_period(TIMER0_id, get_sclk() / HZ);
 173                 set_gptimer_pwidth(TIMER0_id, get_sclk() / HZ - 1);
 174                 enable_gptimers(TIMER0bit);
 175                 break;
 176         }
 177         case CLOCK_EVT_MODE_ONESHOT:
 178                 disable_gptimers(TIMER0bit);
 179                 set_gptimer_config(TIMER0_id, \
 180                         TIMER_OUT_DIS | TIMER_IRQ_ENA | TIMER_MODE_PWM);
 181                 set_gptimer_period(TIMER0_id, 0);
 182                 break;
 183         case CLOCK_EVT_MODE_UNUSED:
 184         case CLOCK_EVT_MODE_SHUTDOWN:
 185                 disable_gptimers(TIMER0bit);
 186                 break;
 187         case CLOCK_EVT_MODE_RESUME:
 188                 break;
 189         }
 190 }
 191
 192 static void bfin_gptmr0_ack(void)
 193 {
 194         set_gptimer_status(TIMER_GROUP1, TIMER_STATUS_TIMIL0);
 195 }
 196
 197 static void __init bfin_gptmr0_init(void)
 198 {
 199         disable_gptimers(TIMER0bit);
 200 }
 201
 202 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 203 __attribute__((l1_text))
 204 #endif
 205 irqreturn_t bfin_gptmr0_interrupt(int irq, void *dev_id)
 206 {
 207         struct clock_event_device *evt = dev_id;
 208         smp_mb();
 209         /*
 210          * We want to ACK before we handle so that we can handle smaller timer
 211          * intervals.  This way if the timer expires again while we're handling
 212          * things, we're more likely to see that 2nd int rather than swallowing
 213          * it by ACKing the int at the end of this handler.
 214          */
 215         bfin_gptmr0_ack();
 216         evt->event_handler(evt);
 217         return IRQ_HANDLED;
 218 }
 219
 220 static struct irqaction gptmr0_irq = {
 221         .name           = "Blackfin GPTimer0",
 222         .flags          = IRQF_DISABLED | IRQF_TIMER | \
 223                           IRQF_IRQPOLL | IRQF_PERCPU,
 224         .handler        = bfin_gptmr0_interrupt,
 225 };
 226
 227 static struct clock_event_device clockevent_gptmr0 = {
 228         .name           = "bfin_gptimer0",
 229         .rating         = 300,
 230         .irq            = IRQ_TIMER0,
 231         .shift          = 32,
 232         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 233         .set_next_event = bfin_gptmr0_set_next_event,
 234         .set_mode       = bfin_gptmr0_set_mode,
 235 };
 236
 237 static void __init bfin_gptmr0_clockevent_init(struct clock_event_device *evt)
 238 {
 239         unsigned long clock_tick;
 240
 241         clock_tick = get_sclk();
 242         evt->mult = div_sc(clock_tick, NSEC_PER_SEC, evt->shift);
 243         evt->max_delta_ns = clockevent_delta2ns(-1, evt);
 244         evt->min_delta_ns = clockevent_delta2ns(100, evt);
 245
 246         evt->cpumask = cpumask_of(0);
 247
 248         clockevents_register_device(evt);
 249 }
 250 #endif /* CONFIG_TICKSOURCE_GPTMR0 */
 251
 252 #if defined(CONFIG_TICKSOURCE_CORETMR)
 253 /* per-cpu local core timer */
 254 static DEFINE_PER_CPU(struct clock_event_device, coretmr_events);
 255
 256 static int bfin_coretmr_set_next_event(unsigned long cycles,
 257                                 struct clock_event_device *evt)
 258 {
 259         bfin_write_TCNTL(TMPWR);
 260         CSYNC();
 261         bfin_write_TCOUNT(cycles);
 262         CSYNC();
 263         bfin_write_TCNTL(TMPWR | TMREN);
 264         return 0;
 265 }
 266
 267 static void bfin_coretmr_set_mode(enum clock_event_mode mode,
 268                                 struct clock_event_device *evt)
 269 {
 270         switch (mode) {
 271         case CLOCK_EVT_MODE_PERIODIC: {
 272                 unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
 273                 bfin_write_TCNTL(TMPWR);
 274                 CSYNC();
 275                 bfin_write_TSCALE(TIME_SCALE - 1);
 276                 bfin_write_TPERIOD(tcount);
 277                 bfin_write_TCOUNT(tcount);
 278                 CSYNC();
 279                 bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
 280                 break;
 281         }
 282         case CLOCK_EVT_MODE_ONESHOT:
 283                 bfin_write_TCNTL(TMPWR);
 284                 CSYNC();
 285                 bfin_write_TSCALE(TIME_SCALE - 1);
 286                 bfin_write_TPERIOD(0);
 287                 bfin_write_TCOUNT(0);
 288                 break;
 289         case CLOCK_EVT_MODE_UNUSED:
 290         case CLOCK_EVT_MODE_SHUTDOWN:
 291                 bfin_write_TCNTL(0);
 292                 CSYNC();
 293                 break;
 294         case CLOCK_EVT_MODE_RESUME:
 295                 break;
 296         }
 297 }
 298
 299 void bfin_coretmr_init(void)
 300 {
 301         /* power up the timer, but don't enable it just yet */
 302         bfin_write_TCNTL(TMPWR);
 303         CSYNC();
 304
 305         /* the TSCALE prescaler counter. */
 306         bfin_write_TSCALE(TIME_SCALE - 1);
 307         bfin_write_TPERIOD(0);
 308         bfin_write_TCOUNT(0);
 309
 310         CSYNC();
 311 }
 312
 313 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 314 __attribute__((l1_text))
 315 #endif
 316 irqreturn_t bfin_coretmr_interrupt(int irq, void *dev_id)
 317 {
 318         int cpu = smp_processor_id();
 319         struct clock_event_device *evt = &per_cpu(coretmr_events, cpu);
 320
 321         smp_mb();
 322         evt->event_handler(evt);
 323
 324         touch_nmi_watchdog();
 325
 326         return IRQ_HANDLED;
 327 }
 328
 329 static struct irqaction coretmr_irq = {
 330         .name           = "Blackfin CoreTimer",
 331         .flags          = IRQF_DISABLED | IRQF_TIMER | \
 332                           IRQF_IRQPOLL | IRQF_PERCPU,
 333         .handler        = bfin_coretmr_interrupt,
 334 };
 335
 336 void bfin_coretmr_clockevent_init(void)
 337 {
 338         unsigned long clock_tick;
 339         unsigned int cpu = smp_processor_id();
 340         struct clock_event_device *evt = &per_cpu(coretmr_events, cpu);
 341
 342         evt->name = "bfin_core_timer";
 343         evt->rating = 350;
 344         evt->irq = -1;
 345         evt->shift = 32;
 346         evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 347         evt->set_next_event = bfin_coretmr_set_next_event;
 348         evt->set_mode = bfin_coretmr_set_mode;
 349
 350         clock_tick = get_cclk() / TIME_SCALE;
 351         evt->mult = div_sc(clock_tick, NSEC_PER_SEC, evt->shift);
 352         evt->max_delta_ns = clockevent_delta2ns(-1, evt);
 353         evt->min_delta_ns = clockevent_delta2ns(100, evt);
 354
 355         evt->cpumask = cpumask_of(cpu);
 356
 357         clockevents_register_device(evt);
 358 }
 359 #endif /* CONFIG_TICKSOURCE_CORETMR */
 360
 361
 362 void read_persistent_clock(struct timespec *ts)
 363 {
 364         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 365         ts->tv_sec = secs_since_1970;
 366         ts->tv_nsec = 0;
 367 }
 368
 369 void __init time_init(void)
 370 {
 371
 372 #ifdef CONFIG_RTC_DRV_BFIN
 373         /* [#2663] hack to filter junk RTC values that would cause
 374          * userspace to have to deal with time values greater than
 375          * 2^31 seconds (which uClibc cannot cope with yet)
 376          */
 377         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 378                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 379                 bfin_write_RTC_STAT(0);
 380         }
 381 #endif
 382
 383         bfin_cs_cycles_init();
 384         bfin_cs_gptimer0_init();
 385
 386 #if defined(CONFIG_TICKSOURCE_CORETMR)
 387         bfin_coretmr_init();
 388         setup_irq(IRQ_CORETMR, &coretmr_irq);
 389         bfin_coretmr_clockevent_init();
 390 #endif
 391
 392 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 393         bfin_gptmr0_init();
 394         setup_irq(IRQ_TIMER0, &gptmr0_irq);
 395         gptmr0_irq.dev_id = &clockevent_gptmr0;
 396         bfin_gptmr0_clockevent_init(&clockevent_gptmr0);
 397 #endif
 398
 399 #if !defined(CONFIG_TICKSOURCE_CORETMR) && !defined(CONFIG_TICKSOURCE_GPTMR0)
 400 # error at least one clock event device is required
 401 #endif
 402 }