arch/blackfin/kernel/time-ts.c

   1 /*
   2  * linux/arch/kernel/time-ts.c
   3  *
   4  * Based on arm clockevents implementation and old bfin time tick.
   5  *
   6  * Copyright(C) 2008, GeoTechnologies, Vitja Makarov
   7  *
   8  * This code is licenced under the GPL version 2. For details see
   9  * kernel-base/COPYING.
  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 #if defined(CONFIG_CYCLES_CLOCKSOURCE)
  26
  27 /* Accelerators for sched_clock()
  28  * convert from cycles(64bits) => nanoseconds (64bits)
  29  *  basic equation:
  30  *              ns = cycles / (freq / ns_per_sec)
  31  *              ns = cycles * (ns_per_sec / freq)
  32  *              ns = cycles * (10^9 / (cpu_khz * 10^3))
  33  *              ns = cycles * (10^6 / cpu_khz)
  34  *
  35  *      Then we use scaling math (suggested by george@mvista.com) to get:
  36  *              ns = cycles * (10^6 * SC / cpu_khz) / SC
  37  *              ns = cycles * cyc2ns_scale / SC
  38  *
  39  *      And since SC is a constant power of two, we can convert the div
  40  *  into a shift.
  41  *
  42  *  We can use khz divisor instead of mhz to keep a better precision, since
  43  *  cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
  44  *  (mathieu.desnoyers@polymtl.ca)
  45  *
  46  *                      -johnstul@us.ibm.com "math is hard, lets go shopping!"
  47  */
  48
  49 static unsigned long cyc2ns_scale;
  50 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
  51
  52 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
  53 {
  54         cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
  55 }
  56
  57 static inline unsigned long long cycles_2_ns(cycle_t cyc)
  58 {
  59         return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
  60 }
  61
  62 static cycle_t bfin_read_cycles(struct clocksource *cs)
  63 {
  64         return __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod);
  65 }
  66
  67 static struct clocksource bfin_cs_cycles = {
  68         .name           = "bfin_cs_cycles",
  69         .rating         = 350,
  70         .read           = bfin_read_cycles,
  71         .mask           = CLOCKSOURCE_MASK(64),
  72         .shift          = 22,
  73         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  74 };
  75
  76 unsigned long long sched_clock(void)
  77 {
  78         return cycles_2_ns(bfin_read_cycles(&bfin_cs_cycles));
  79 }
  80
  81 static int __init bfin_cs_cycles_init(void)
  82 {
  83         set_cyc2ns_scale(get_cclk() / 1000);
  84
  85         bfin_cs_cycles.mult = \
  86                 clocksource_hz2mult(get_cclk(), bfin_cs_cycles.shift);
  87
  88         if (clocksource_register(&bfin_cs_cycles))
  89                 panic("failed to register clocksource");
  90
  91         return 0;
  92 }
  93 #else
  94 # define bfin_cs_cycles_init()
  95 #endif
  96
  97 #ifdef CONFIG_GPTMR0_CLOCKSOURCE
  98
  99 void __init setup_gptimer0(void)
 100 {
 101         disable_gptimers(TIMER0bit);
 102
 103         set_gptimer_config(TIMER0_id, \
 104                 TIMER_OUT_DIS | TIMER_PERIOD_CNT | TIMER_MODE_PWM);
 105         set_gptimer_period(TIMER0_id, -1);
 106         set_gptimer_pwidth(TIMER0_id, -2);
 107         SSYNC();
 108         enable_gptimers(TIMER0bit);
 109 }
 110
 111 static cycle_t bfin_read_gptimer0(void)
 112 {
 113         return bfin_read_TIMER0_COUNTER();
 114 }
 115
 116 static struct clocksource bfin_cs_gptimer0 = {
 117         .name           = "bfin_cs_gptimer0",
 118         .rating         = 400,
 119         .read           = bfin_read_gptimer0,
 120         .mask           = CLOCKSOURCE_MASK(32),
 121         .shift          = 22,
 122         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 123 };
 124
 125 static int __init bfin_cs_gptimer0_init(void)
 126 {
 127         setup_gptimer0();
 128
 129         bfin_cs_gptimer0.mult = \
 130                 clocksource_hz2mult(get_sclk(), bfin_cs_gptimer0.shift);
 131
 132         if (clocksource_register(&bfin_cs_gptimer0))
 133                 panic("failed to register clocksource");
 134
 135         return 0;
 136 }
 137 #else
 138 # define bfin_cs_gptimer0_init()
 139 #endif
 140
 141 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 142 __attribute__((l1_text))
 143 #endif
 144 irqreturn_t timer_interrupt(int irq, void *dev_id);
 145
 146 static int bfin_timer_set_next_event(unsigned long, \
 147                 struct clock_event_device *);
 148
 149 static void bfin_timer_set_mode(enum clock_event_mode, \
 150                 struct clock_event_device *);
 151
 152 static struct clock_event_device clockevent_bfin = {
 153 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 154         .name           = "bfin_gptimer0",
 155         .rating         = 300,
 156         .irq            = IRQ_TIMER0,
 157 #else
 158         .name           = "bfin_core_timer",
 159         .rating         = 350,
 160         .irq            = IRQ_CORETMR,
 161 #endif
 162         .shift          = 32,
 163         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 164         .set_next_event = bfin_timer_set_next_event,
 165         .set_mode       = bfin_timer_set_mode,
 166 };
 167
 168 static struct irqaction bfin_timer_irq = {
 169 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 170         .name           = "Blackfin GPTimer0",
 171 #else
 172         .name           = "Blackfin CoreTimer",
 173 #endif
 174         .flags          = IRQF_DISABLED | IRQF_TIMER | \
 175                           IRQF_IRQPOLL | IRQF_PERCPU,
 176         .handler        = timer_interrupt,
 177         .dev_id         = &clockevent_bfin,
 178 };
 179
 180 #if defined(CONFIG_TICKSOURCE_GPTMR0)
 181 static int bfin_timer_set_next_event(unsigned long cycles,
 182                                      struct clock_event_device *evt)
 183 {
 184         disable_gptimers(TIMER0bit);
 185
 186         /* it starts counting three SCLK cycles after the TIMENx bit is set */
 187         set_gptimer_pwidth(TIMER0_id, cycles - 3);
 188         enable_gptimers(TIMER0bit);
 189         return 0;
 190 }
 191
 192 static void bfin_timer_set_mode(enum clock_event_mode mode,
 193                                 struct clock_event_device *evt)
 194 {
 195         switch (mode) {
 196         case CLOCK_EVT_MODE_PERIODIC: {
 197                 set_gptimer_config(TIMER0_id, \
 198                         TIMER_OUT_DIS | TIMER_IRQ_ENA | \
 199                         TIMER_PERIOD_CNT | TIMER_MODE_PWM);
 200                 set_gptimer_period(TIMER0_id, get_sclk() / HZ);
 201                 set_gptimer_pwidth(TIMER0_id, get_sclk() / HZ - 1);
 202                 enable_gptimers(TIMER0bit);
 203                 break;
 204         }
 205         case CLOCK_EVT_MODE_ONESHOT:
 206                 disable_gptimers(TIMER0bit);
 207                 set_gptimer_config(TIMER0_id, \
 208                         TIMER_OUT_DIS | TIMER_IRQ_ENA | TIMER_MODE_PWM);
 209                 set_gptimer_period(TIMER0_id, 0);
 210                 break;
 211         case CLOCK_EVT_MODE_UNUSED:
 212         case CLOCK_EVT_MODE_SHUTDOWN:
 213                 disable_gptimers(TIMER0bit);
 214                 break;
 215         case CLOCK_EVT_MODE_RESUME:
 216                 break;
 217         }
 218 }
 219
 220 static void bfin_timer_ack(void)
 221 {
 222         set_gptimer_status(TIMER_GROUP1, TIMER_STATUS_TIMIL0);
 223 }
 224
 225 static void __init bfin_timer_init(void)
 226 {
 227         disable_gptimers(TIMER0bit);
 228 }
 229
 230 static unsigned long  __init bfin_clockevent_check(void)
 231 {
 232         setup_irq(IRQ_TIMER0, &bfin_timer_irq);
 233         return get_sclk();
 234 }
 235
 236 #else /* CONFIG_TICKSOURCE_CORETMR */
 237
 238 static int bfin_timer_set_next_event(unsigned long cycles,
 239                                 struct clock_event_device *evt)
 240 {
 241         bfin_write_TCNTL(TMPWR);
 242         CSYNC();
 243         bfin_write_TCOUNT(cycles);
 244         CSYNC();
 245         bfin_write_TCNTL(TMPWR | TMREN);
 246         return 0;
 247 }
 248
 249 static void bfin_timer_set_mode(enum clock_event_mode mode,
 250                                 struct clock_event_device *evt)
 251 {
 252         switch (mode) {
 253         case CLOCK_EVT_MODE_PERIODIC: {
 254                 unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
 255                 bfin_write_TCNTL(TMPWR);
 256                 CSYNC();
 257                 bfin_write_TSCALE(TIME_SCALE - 1);
 258                 bfin_write_TPERIOD(tcount);
 259                 bfin_write_TCOUNT(tcount);
 260                 CSYNC();
 261                 bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
 262                 break;
 263         }
 264         case CLOCK_EVT_MODE_ONESHOT:
 265                 bfin_write_TCNTL(TMPWR);
 266                 CSYNC();
 267                 bfin_write_TSCALE(TIME_SCALE - 1);
 268                 bfin_write_TPERIOD(0);
 269                 bfin_write_TCOUNT(0);
 270                 break;
 271         case CLOCK_EVT_MODE_UNUSED:
 272         case CLOCK_EVT_MODE_SHUTDOWN:
 273                 bfin_write_TCNTL(0);
 274                 CSYNC();
 275                 break;
 276         case CLOCK_EVT_MODE_RESUME:
 277                 break;
 278         }
 279 }
 280
 281 static void bfin_timer_ack(void)
 282 {
 283 }
 284
 285 static void __init bfin_timer_init(void)
 286 {
 287         /* power up the timer, but don't enable it just yet */
 288         bfin_write_TCNTL(TMPWR);
 289         CSYNC();
 290
 291         /*
 292          * the TSCALE prescaler counter.
 293          */
 294         bfin_write_TSCALE(TIME_SCALE - 1);
 295         bfin_write_TPERIOD(0);
 296         bfin_write_TCOUNT(0);
 297
 298         CSYNC();
 299 }
 300
 301 static unsigned long  __init bfin_clockevent_check(void)
 302 {
 303         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
 304         return get_cclk() / TIME_SCALE;
 305 }
 306
 307 void __init setup_core_timer(void)
 308 {
 309         bfin_timer_init();
 310         bfin_timer_set_mode(CLOCK_EVT_MODE_PERIODIC, NULL);
 311 }
 312 #endif /* CONFIG_TICKSOURCE_GPTMR0 */
 313
 314 /*
 315  * timer_interrupt() needs to keep up the real-time clock,
 316  * as well as call the "do_timer()" routine every clocktick
 317  */
 318 irqreturn_t timer_interrupt(int irq, void *dev_id)
 319 {
 320         struct clock_event_device *evt = dev_id;
 321         smp_mb();
 322         evt->event_handler(evt);
 323         bfin_timer_ack();
 324         return IRQ_HANDLED;
 325 }
 326
 327 static int __init bfin_clockevent_init(void)
 328 {
 329         unsigned long timer_clk;
 330
 331         timer_clk = bfin_clockevent_check();
 332
 333         bfin_timer_init();
 334
 335         clockevent_bfin.mult = div_sc(timer_clk, NSEC_PER_SEC, clockevent_bfin.shift);
 336         clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin);
 337         clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin);
 338         clockevent_bfin.cpumask = cpumask_of(0);
 339         clockevents_register_device(&clockevent_bfin);
 340
 341         return 0;
 342 }
 343
 344 void __init time_init(void)
 345 {
 346         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 347
 348 #ifdef CONFIG_RTC_DRV_BFIN
 349         /* [#2663] hack to filter junk RTC values that would cause
 350          * userspace to have to deal with time values greater than
 351          * 2^31 seconds (which uClibc cannot cope with yet)
 352          */
 353         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 354                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 355                 bfin_write_RTC_STAT(0);
 356         }
 357 #endif
 358
 359         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 360         xtime.tv_sec = secs_since_1970;
 361         xtime.tv_nsec = 0;
 362         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
 363
 364         bfin_cs_cycles_init();
 365         bfin_cs_gptimer0_init();
 366         bfin_clockevent_init();
 367 }