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
  25 /* Accelerators for sched_clock()
  26  * convert from cycles(64bits) => nanoseconds (64bits)
  27  *  basic equation:
  28  *              ns = cycles / (freq / ns_per_sec)
  29  *              ns = cycles * (ns_per_sec / freq)
  30  *              ns = cycles * (10^9 / (cpu_khz * 10^3))
  31  *              ns = cycles * (10^6 / cpu_khz)
  32  *
  33  *      Then we use scaling math (suggested by george@mvista.com) to get:
  34  *              ns = cycles * (10^6 * SC / cpu_khz) / SC
  35  *              ns = cycles * cyc2ns_scale / SC
  36  *
  37  *      And since SC is a constant power of two, we can convert the div
  38  *  into a shift.
  39  *
  40  *  We can use khz divisor instead of mhz to keep a better precision, since
  41  *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
  42  *  (mathieu.desnoyers@polymtl.ca)
  43  *
  44  *                      -johnstul@us.ibm.com "math is hard, lets go shopping!"
  45  */
  46
  47 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
  48
  49 static inline unsigned long cyc2ns_scale(unsigned long cpu_khz)
  50 {
  51         return (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
  52 }
  53
  54 static inline unsigned long long cycles_2_ns(cycle_t cyc, unsigned long cyc2ns_scale)
  55 {
  56         return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
  57 }
  58
  59 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
  60
  61 static unsigned long cycles_cyc2ns_scale;
  62
  63 static notrace cycle_t bfin_read_cycles(struct clocksource *cs)
  64 {
  65         return __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod);
  66 }
  67
  68 static struct clocksource bfin_cs_cycles = {
  69         .name           = "bfin_cs_cycles",
  70         .rating         = 400,
  71         .read           = bfin_read_cycles,
  72         .mask           = CLOCKSOURCE_MASK(64),
  73         .shift          = 22,
  74         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  75 };
  76
  77 static inline unsigned long long bfin_cs_cycles_sched_clock(void)
  78 {
  79         return cycles_2_ns(bfin_read_cycles(&bfin_cs_cycles), cycles_cyc2ns_scale);
  80 }
  81
  82 static int __init bfin_cs_cycles_init(void)
  83 {
  84         cycles_cyc2ns_scale = cyc2ns_scale(get_cclk() / 1000);
  85
  86         bfin_cs_cycles.mult = \
  87                 clocksource_hz2mult(get_cclk(), bfin_cs_cycles.shift);
  88
  89         if (clocksource_register(&bfin_cs_cycles))
  90                 panic("failed to register clocksource");
  91
  92         return 0;
  93 }
  94 #else
  95 # define bfin_cs_cycles_init()
  96 #endif
  97
  98 #ifdef CONFIG_GPTMR0_CLOCKSOURCE
  99
 100 unsigned long gptimer0_cyc2ns_scale;
 101
 102 void __init setup_gptimer0(void)
 103 {
 104         disable_gptimers(TIMER0bit);
 105
 106         set_gptimer_config(TIMER0_id, \
 107                 TIMER_OUT_DIS | TIMER_PERIOD_CNT | TIMER_MODE_PWM);
 108         set_gptimer_period(TIMER0_id, -1);
 109         set_gptimer_pwidth(TIMER0_id, -2);
 110         SSYNC();
 111         enable_gptimers(TIMER0bit);
 112 }
 113
 114 static cycle_t bfin_read_gptimer0(struct clocksource *cs)
 115 {
 116         return bfin_read_TIMER0_COUNTER();
 117 }
 118
 119 static struct clocksource bfin_cs_gptimer0 = {
 120         .name           = "bfin_cs_gptimer0",
 121         .rating         = 350,
 122         .read           = bfin_read_gptimer0,
 123         .mask           = CLOCKSOURCE_MASK(32),
 124         .shift          = 22,
 125         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 126 };
 127
 128 static inline unsigned long long bfin_cs_gptimer0_sched_clock(void)
 129 {
 130         return cycles_2_ns(bfin_read_TIMER0_COUNTER(), gptimer0_cyc2ns_scale);
 131 }
 132
 133 static int __init bfin_cs_gptimer0_init(void)
 134 {
 135         gptimer0_cyc2ns_scale = cyc2ns_scale(get_sclk() / 1000);
 136
 137         setup_gptimer0();
 138
 139         bfin_cs_gptimer0.mult = \
 140                 clocksource_hz2mult(get_sclk(), bfin_cs_gptimer0.shift);
 141
 142         if (clocksource_register(&bfin_cs_gptimer0))
 143                 panic("failed to register clocksource");
 144
 145         return 0;
 146 }
 147 #else
 148 # define bfin_cs_gptimer0_init()
 149 #endif
 150
 151
 152 #if defined(CONFIG_GPTMR0_CLOCKSOURCE) || defined(CONFIG_CYCLES_CLOCKSOURCE)
 153 /* prefer to use cycles since it has higher rating */
 154 notrace unsigned long long sched_clock(void)
 155 {
 156 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
 157         return bfin_cs_cycles_sched_clock();
 158 #else
 159         return bfin_cs_gptimer0_sched_clock();
 160 #endif
 161 }
 162 #endif
 163
 164 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 165 __attribute__((l1_text))
 166 #endif
 167 irqreturn_t timer_interrupt(int irq, void *dev_id);
 168
 169 static int bfin_timer_set_next_event(unsigned long, \
 170                 struct clock_event_device *);
 171
 172 static void bfin_timer_set_mode(enum clock_event_mode, \
 173                 struct clock_event_device *);
 174
 175 static struct clock_event_device clockevent_bfin = {
 176 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 177         .name           = "bfin_gptimer0",
 178         .rating         = 300,
 179         .irq            = IRQ_TIMER0,
 180 #else
 181         .name           = "bfin_core_timer",
 182         .rating         = 350,
 183         .irq            = IRQ_CORETMR,
 184 #endif
 185         .shift          = 32,
 186         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 187         .set_next_event = bfin_timer_set_next_event,
 188         .set_mode       = bfin_timer_set_mode,
 189 };
 190
 191 static struct irqaction bfin_timer_irq = {
 192 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 193         .name           = "Blackfin GPTimer0",
 194 #else
 195         .name           = "Blackfin CoreTimer",
 196 #endif
 197         .flags          = IRQF_DISABLED | IRQF_TIMER | \
 198                           IRQF_IRQPOLL | IRQF_PERCPU,
 199         .handler        = timer_interrupt,
 200         .dev_id         = &clockevent_bfin,
 201 };
 202
 203 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 204 static int bfin_timer_set_next_event(unsigned long cycles,
 205                                      struct clock_event_device *evt)
 206 {
 207         disable_gptimers(TIMER0bit);
 208
 209         /* it starts counting three SCLK cycles after the TIMENx bit is set */
 210         set_gptimer_pwidth(TIMER0_id, cycles - 3);
 211         enable_gptimers(TIMER0bit);
 212         return 0;
 213 }
 214
 215 static void bfin_timer_set_mode(enum clock_event_mode mode,
 216                                 struct clock_event_device *evt)
 217 {
 218         switch (mode) {
 219         case CLOCK_EVT_MODE_PERIODIC: {
 220                 set_gptimer_config(TIMER0_id, \
 221                         TIMER_OUT_DIS | TIMER_IRQ_ENA | \
 222                         TIMER_PERIOD_CNT | TIMER_MODE_PWM);
 223                 set_gptimer_period(TIMER0_id, get_sclk() / HZ);
 224                 set_gptimer_pwidth(TIMER0_id, get_sclk() / HZ - 1);
 225                 enable_gptimers(TIMER0bit);
 226                 break;
 227         }
 228         case CLOCK_EVT_MODE_ONESHOT:
 229                 disable_gptimers(TIMER0bit);
 230                 set_gptimer_config(TIMER0_id, \
 231                         TIMER_OUT_DIS | TIMER_IRQ_ENA | TIMER_MODE_PWM);
 232                 set_gptimer_period(TIMER0_id, 0);
 233                 break;
 234         case CLOCK_EVT_MODE_UNUSED:
 235         case CLOCK_EVT_MODE_SHUTDOWN:
 236                 disable_gptimers(TIMER0bit);
 237                 break;
 238         case CLOCK_EVT_MODE_RESUME:
 239                 break;
 240         }
 241 }
 242
 243 static void bfin_timer_ack(void)
 244 {
 245         set_gptimer_status(TIMER_GROUP1, TIMER_STATUS_TIMIL0);
 246 }
 247
 248 static void __init bfin_timer_init(void)
 249 {
 250         disable_gptimers(TIMER0bit);
 251 }
 252
 253 static unsigned long  __init bfin_clockevent_check(void)
 254 {
 255         setup_irq(IRQ_TIMER0, &bfin_timer_irq);
 256         return get_sclk();
 257 }
 258
 259 #else /* CONFIG_TICKSOURCE_CORETMR */
 260
 261 static int bfin_timer_set_next_event(unsigned long cycles,
 262                                 struct clock_event_device *evt)
 263 {
 264         bfin_write_TCNTL(TMPWR);
 265         CSYNC();
 266         bfin_write_TCOUNT(cycles);
 267         CSYNC();
 268         bfin_write_TCNTL(TMPWR | TMREN);
 269         return 0;
 270 }
 271
 272 static void bfin_timer_set_mode(enum clock_event_mode mode,
 273                                 struct clock_event_device *evt)
 274 {
 275         switch (mode) {
 276         case CLOCK_EVT_MODE_PERIODIC: {
 277                 unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
 278                 bfin_write_TCNTL(TMPWR);
 279                 CSYNC();
 280                 bfin_write_TSCALE(TIME_SCALE - 1);
 281                 bfin_write_TPERIOD(tcount);
 282                 bfin_write_TCOUNT(tcount);
 283                 CSYNC();
 284                 bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
 285                 break;
 286         }
 287         case CLOCK_EVT_MODE_ONESHOT:
 288                 bfin_write_TCNTL(TMPWR);
 289                 CSYNC();
 290                 bfin_write_TSCALE(TIME_SCALE - 1);
 291                 bfin_write_TPERIOD(0);
 292                 bfin_write_TCOUNT(0);
 293                 break;
 294         case CLOCK_EVT_MODE_UNUSED:
 295         case CLOCK_EVT_MODE_SHUTDOWN:
 296                 bfin_write_TCNTL(0);
 297                 CSYNC();
 298                 break;
 299         case CLOCK_EVT_MODE_RESUME:
 300                 break;
 301         }
 302 }
 303
 304 static void bfin_timer_ack(void)
 305 {
 306 }
 307
 308 static void __init bfin_timer_init(void)
 309 {
 310         /* power up the timer, but don't enable it just yet */
 311         bfin_write_TCNTL(TMPWR);
 312         CSYNC();
 313
 314         /*
 315          * the TSCALE prescaler counter.
 316          */
 317         bfin_write_TSCALE(TIME_SCALE - 1);
 318         bfin_write_TPERIOD(0);
 319         bfin_write_TCOUNT(0);
 320
 321         CSYNC();
 322 }
 323
 324 static unsigned long  __init bfin_clockevent_check(void)
 325 {
 326         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
 327         return get_cclk() / TIME_SCALE;
 328 }
 329
 330 void __init setup_core_timer(void)
 331 {
 332         bfin_timer_init();
 333         bfin_timer_set_mode(CLOCK_EVT_MODE_PERIODIC, NULL);
 334 }
 335 #endif /* CONFIG_TICKSOURCE_GPTMR0 */
 336
 337 /*
 338  * timer_interrupt() needs to keep up the real-time clock,
 339  * as well as call the "do_timer()" routine every clocktick
 340  */
 341 irqreturn_t timer_interrupt(int irq, void *dev_id)
 342 {
 343         struct clock_event_device *evt = dev_id;
 344         smp_mb();
 345         evt->event_handler(evt);
 346         bfin_timer_ack();
 347         return IRQ_HANDLED;
 348 }
 349
 350 static int __init bfin_clockevent_init(void)
 351 {
 352         unsigned long timer_clk;
 353
 354         timer_clk = bfin_clockevent_check();
 355
 356         bfin_timer_init();
 357
 358         clockevent_bfin.mult = div_sc(timer_clk, NSEC_PER_SEC, clockevent_bfin.shift);
 359         clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin);
 360         clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin);
 361         clockevent_bfin.cpumask = cpumask_of(0);
 362         clockevents_register_device(&clockevent_bfin);
 363
 364         return 0;
 365 }
 366
 367 void __init time_init(void)
 368 {
 369         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 370
 371 #ifdef CONFIG_RTC_DRV_BFIN
 372         /* [#2663] hack to filter junk RTC values that would cause
 373          * userspace to have to deal with time values greater than
 374          * 2^31 seconds (which uClibc cannot cope with yet)
 375          */
 376         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 377                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 378                 bfin_write_RTC_STAT(0);
 379         }
 380 #endif
 381
 382         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 383         xtime.tv_sec = secs_since_1970;
 384         xtime.tv_nsec = 0;
 385         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
 386
 387         bfin_cs_cycles_init();
 388         bfin_cs_gptimer0_init();
 389         bfin_clockevent_init();
 390 }