arch/blackfin/kernel/time.c

   1 /*
   2  * arch/blackfin/kernel/time.c
   3  *
   4  * This file contains the Blackfin-specific time handling details.
   5  * Most of the stuff is located in the machine specific files.
   6  *
   7  * Copyright 2004-2008 Analog Devices Inc.
   8  * Licensed under the GPL-2 or later.
   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/irq.h>
  16 #include <linux/delay.h>
  17 #include <linux/sched.h>
  18
  19 #include <asm/blackfin.h>
  20 #include <asm/time.h>
  21 #include <asm/gptimers.h>
  22
  23 /* This is an NTP setting */
  24 #define TICK_SIZE (tick_nsec / 1000)
  25
  26 static struct irqaction bfin_timer_irq = {
  27         .name = "Blackfin Timer Tick",
  28 };
  29
  30 #if defined(CONFIG_IPIPE)
  31 void __init setup_system_timer0(void)
  32 {
  33         /* Power down the core timer, just to play safe. */
  34         bfin_write_TCNTL(0);
  35
  36         disable_gptimers(TIMER0bit);
  37         set_gptimer_status(0, TIMER_STATUS_TRUN0);
  38         while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
  39                 udelay(10);
  40
  41         set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
  42         set_gptimer_period(TIMER0_id, get_sclk() / HZ);
  43         set_gptimer_pwidth(TIMER0_id, 1);
  44         SSYNC();
  45         enable_gptimers(TIMER0bit);
  46 }
  47 #else
  48 void __init setup_core_timer(void)
  49 {
  50         u32 tcount;
  51
  52         /* power up the timer, but don't enable it just yet */
  53         bfin_write_TCNTL(TMPWR);
  54         CSYNC();
  55
  56         /* the TSCALE prescaler counter */
  57         bfin_write_TSCALE(TIME_SCALE - 1);
  58
  59         tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
  60         bfin_write_TPERIOD(tcount);
  61         bfin_write_TCOUNT(tcount);
  62
  63         /* now enable the timer */
  64         CSYNC();
  65
  66         bfin_write_TCNTL(TAUTORLD | TMREN | TMPWR);
  67 }
  68 #endif
  69
  70 static void __init
  71 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
  72 {
  73 #if defined(CONFIG_IPIPE)
  74         setup_system_timer0();
  75         bfin_timer_irq.handler = timer_routine;
  76         setup_irq(IRQ_TIMER0, &bfin_timer_irq);
  77 #else
  78         setup_core_timer();
  79         bfin_timer_irq.handler = timer_routine;
  80         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
  81 #endif
  82 }
  83
  84 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  85 /*
  86  * Should return useconds since last timer tick
  87  */
  88 static u32 blackfin_gettimeoffset(void)
  89 {
  90         unsigned long offset;
  91         unsigned long clocks_per_jiffy;
  92
  93 #if defined(CONFIG_IPIPE)
  94         clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
  95         offset = bfin_read_TIMER0_COUNTER() / \
  96                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
  97
  98         if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
  99                 offset += (USEC_PER_SEC / HZ);
 100 #else
 101         clocks_per_jiffy = bfin_read_TPERIOD();
 102         offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
 103                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
 104
 105         /* Check if we just wrapped the counters and maybe missed a tick */
 106         if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
 107                 && (offset < (100000 / HZ / 2)))
 108                 offset += (USEC_PER_SEC / HZ);
 109 #endif
 110         return offset;
 111 }
 112 #endif
 113
 114 /*
 115  * timer_interrupt() needs to keep up the real-time clock,
 116  * as well as call the "xtime_update()" routine every clocktick
 117  */
 118 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 119 __attribute__((l1_text))
 120 #endif
 121 irqreturn_t timer_interrupt(int irq, void *dummy)
 122 {
 123         xtime_update(1);
 124
 125 #ifdef CONFIG_IPIPE
 126         update_root_process_times(get_irq_regs());
 127 #else
 128         update_process_times(user_mode(get_irq_regs()));
 129 #endif
 130         profile_tick(CPU_PROFILING);
 131
 132         return IRQ_HANDLED;
 133 }
 134
 135 void read_persistent_clock(struct timespec *ts)
 136 {
 137         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 138         ts->tv_sec = secs_since_1970;
 139         ts->tv_nsec = 0;
 140 }
 141
 142 void __init time_init(void)
 143 {
 144 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 145         arch_gettimeoffset = blackfin_gettimeoffset;
 146 #endif
 147
 148 #ifdef CONFIG_RTC_DRV_BFIN
 149         /* [#2663] hack to filter junk RTC values that would cause
 150          * userspace to have to deal with time values greater than
 151          * 2^31 seconds (which uClibc cannot cope with yet)
 152          */
 153         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 154                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 155                 bfin_write_RTC_STAT(0);
 156         }
 157 #endif
 158
 159         time_sched_init(timer_interrupt);
 160 }