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   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/irq.h>
  16 #include <linux/clocksource.h>
  17 #include <linux/clockchips.h>
  18
  19 #include <asm/blackfin.h>
  20
  21 #ifdef CONFIG_CYCLES_CLOCKSOURCE
  22
  23 static unsigned long cyc2ns_scale;
  24 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
  25
  26 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
  27 {
  28         cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
  29 }
  30
  31 static inline unsigned long long cycles_2_ns(cycle_t cyc)
  32 {
  33         return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
  34 }
  35
  36 static cycle_t read_cycles(void)
  37 {
  38         unsigned long tmp, tmp2;
  39         asm("%0 = cycles; %1 = cycles2;" : "=d"(tmp), "=d"(tmp2));
  40         return tmp | ((cycle_t)tmp2 << 32);
  41 }
  42
  43 unsigned long long sched_clock(void)
  44 {
  45         return cycles_2_ns(read_cycles());
  46 }
  47
  48 static struct clocksource clocksource_bfin = {
  49         .name           = "bfin_cycles",
  50         .rating         = 350,
  51         .read           = read_cycles,
  52         .mask           = CLOCKSOURCE_MASK(64),
  53         .shift          = 22,
  54         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  55 };
  56
  57 static int __init bfin_clocksource_init(void)
  58 {
  59         set_cyc2ns_scale(get_cclk() / 1000);
  60
  61         clocksource_bfin.mult = clocksource_hz2mult(get_cclk(), clocksource_bfin.shift);
  62
  63         if (clocksource_register(&clocksource_bfin))
  64                 panic("failed to register clocksource");
  65
  66         return 0;
  67 }
  68
  69 #else
  70 # define bfin_clocksource_init()
  71 #endif
  72
  73 static int bfin_timer_set_next_event(unsigned long cycles,
  74                                      struct clock_event_device *evt)
  75 {
  76         bfin_write_TCOUNT(cycles);
  77         CSYNC();
  78         return 0;
  79 }
  80
  81 static void bfin_timer_set_mode(enum clock_event_mode mode,
  82                                 struct clock_event_device *evt)
  83 {
  84         switch (mode) {
  85         case CLOCK_EVT_MODE_PERIODIC: {
  86                 unsigned long tcount = ((get_cclk() / (HZ * 1)) - 1);
  87                 bfin_write_TCNTL(TMPWR);
  88                 CSYNC();
  89                 bfin_write_TPERIOD(tcount);
  90                 bfin_write_TCOUNT(tcount);
  91                 bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
  92                 CSYNC();
  93                 break;
  94         }
  95         case CLOCK_EVT_MODE_ONESHOT:
  96                 bfin_write_TCOUNT(0);
  97                 bfin_write_TCNTL(TMPWR | TMREN);
  98                 CSYNC();
  99                 break;
 100         case CLOCK_EVT_MODE_UNUSED:
 101         case CLOCK_EVT_MODE_SHUTDOWN:
 102                 bfin_write_TCNTL(0);
 103                 CSYNC();
 104                 break;
 105         case CLOCK_EVT_MODE_RESUME:
 106                 break;
 107         }
 108 }
 109
 110 static void __init bfin_timer_init(void)
 111 {
 112         /* power up the timer, but don't enable it just yet */
 113         bfin_write_TCNTL(TMPWR);
 114         CSYNC();
 115
 116         /*
 117          * the TSCALE prescaler counter.
 118          */
 119         bfin_write_TSCALE(0);
 120         bfin_write_TPERIOD(0);
 121         bfin_write_TCOUNT(0);
 122
 123         /* now enable the timer */
 124         CSYNC();
 125 }
 126
 127 /*
 128  * timer_interrupt() needs to keep up the real-time clock,
 129  * as well as call the "do_timer()" routine every clocktick
 130  */
 131 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 132 __attribute__((l1_text))
 133 #endif
 134 irqreturn_t timer_interrupt(int irq, void *dev_id);
 135
 136 static struct clock_event_device clockevent_bfin = {
 137         .name           = "bfin_core_timer",
 138         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 139         .shift          = 32,
 140         .cpumask        = CPU_MASK_CPU0,
 141         .set_next_event = bfin_timer_set_next_event,
 142         .set_mode       = bfin_timer_set_mode,
 143 };
 144
 145 static struct irqaction bfin_timer_irq = {
 146         .name           = "Blackfin Core Timer",
 147         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 148         .handler        = timer_interrupt,
 149         .dev_id         = &clockevent_bfin,
 150 };
 151
 152 irqreturn_t timer_interrupt(int irq, void *dev_id)
 153 {
 154         struct clock_event_device *evt = dev_id;
 155         evt->event_handler(evt);
 156         return IRQ_HANDLED;
 157 }
 158
 159 static int __init bfin_clockevent_init(void)
 160 {
 161         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
 162         bfin_timer_init();
 163
 164         clockevent_bfin.mult = div_sc(get_cclk(), NSEC_PER_SEC, clockevent_bfin.shift);
 165         clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin);
 166         clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin);
 167         clockevents_register_device(&clockevent_bfin);
 168
 169         return 0;
 170 }
 171
 172 void __init time_init(void)
 173 {
 174         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 175
 176 #ifdef CONFIG_RTC_DRV_BFIN
 177         /* [#2663] hack to filter junk RTC values that would cause
 178          * userspace to have to deal with time values greater than
 179          * 2^31 seconds (which uClibc cannot cope with yet)
 180          */
 181         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 182                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 183                 bfin_write_RTC_STAT(0);
 184         }
 185 #endif
 186
 187         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 188         xtime.tv_sec = secs_since_1970;
 189         xtime.tv_nsec = 0;
 190         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
 191
 192         bfin_clocksource_init();
 193         bfin_clockevent_init();
 194 }