arch/mips/mipssim/sim_time.c

   1 #include <linux/types.h>
   2 #include <linux/init.h>
   3 #include <linux/kernel_stat.h>
   4 #include <linux/sched.h>
   5 #include <linux/spinlock.h>
   6 #include <linux/interrupt.h>
   7 #include <linux/mc146818rtc.h>
   8 #include <linux/smp.h>
   9 #include <linux/timex.h>
  10
  11 #include <asm/hardirq.h>
  12 #include <asm/div64.h>
  13 #include <asm/cpu.h>
  14 #include <asm/time.h>
  15 #include <asm/irq.h>
  16 #include <asm/mc146818-time.h>
  17 #include <asm/msc01_ic.h>
  18
  19 #include <asm/mips-boards/generic.h>
  20 #include <asm/mips-boards/prom.h>
  21 #include <asm/mips-boards/simint.h>
  22
  23
  24 unsigned long cpu_khz;
  25
  26 /*
  27  * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
  28  */
  29 static unsigned int __init estimate_cpu_frequency(void)
  30 {
  31         unsigned int prid = read_c0_prid() & 0xffff00;
  32         unsigned int count;
  33
  34 #if 1
  35         /*
  36          * hardwire the board frequency to 12MHz.
  37          */
  38
  39         if ((prid == (PRID_COMP_MIPS | PRID_IMP_20KC)) ||
  40             (prid == (PRID_COMP_MIPS | PRID_IMP_25KF)))
  41                 count = 12000000;
  42         else
  43                 count =  6000000;
  44 #else
  45         unsigned int flags;
  46
  47         local_irq_save(flags);
  48
  49         /* Start counter exactly on falling edge of update flag */
  50         while (CMOS_READ(RTC_REG_A) & RTC_UIP);
  51         while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
  52
  53         /* Start r4k counter. */
  54         write_c0_count(0);
  55
  56         /* Read counter exactly on falling edge of update flag */
  57         while (CMOS_READ(RTC_REG_A) & RTC_UIP);
  58         while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
  59
  60         count = read_c0_count();
  61
  62         /* restore interrupts */
  63         local_irq_restore(flags);
  64 #endif
  65
  66         mips_hpt_frequency = count;
  67
  68         if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
  69             (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
  70                 count *= 2;
  71
  72         count += 5000;    /* round */
  73         count -= count%10000;
  74
  75         return count;
  76 }
  77
  78 static int mips_cpu_timer_irq;
  79
  80 static void mips_timer_dispatch(void)
  81 {
  82         do_IRQ(mips_cpu_timer_irq);
  83 }
  84
  85
  86 unsigned __init get_c0_compare_int(void)
  87 {
  88 #ifdef MSC01E_INT_BASE
  89         if (cpu_has_veic) {
  90                 set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
  91                 mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
  92         } else {
  93 #endif
  94                 if (cpu_has_vint)
  95                         set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
  96                 mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
  97         }
  98
  99         return mips_cpu_timer_irq;
 100 }
 101
 102 void __init plat_time_init(void)
 103 {
 104         unsigned int est_freq;
 105
 106         /* Set Data mode - binary. */
 107         CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);
 108
 109         est_freq = estimate_cpu_frequency();
 110
 111         printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
 112                (est_freq % 1000000) * 100 / 1000000);
 113
 114         cpu_khz = est_freq / 1000;
 115 }