arch/mips/mti-sead3/sead3-time.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
   7  */
   8 #include <linux/init.h>
   9
  10 #include <asm/setup.h>
  11 #include <asm/time.h>
  12 #include <asm/irq.h>
  13 #include <asm/mips-boards/generic.h>
  14 #include <asm/mips-boards/prom.h>
  15
  16 unsigned long cpu_khz;
  17
  18 static int mips_cpu_timer_irq;
  19 static int mips_cpu_perf_irq;
  20
  21 static void mips_timer_dispatch(void)
  22 {
  23         do_IRQ(mips_cpu_timer_irq);
  24 }
  25
  26 static void mips_perf_dispatch(void)
  27 {
  28         do_IRQ(mips_cpu_perf_irq);
  29 }
  30
  31 static void __iomem *status_reg = (void __iomem *)0xbf000410;
  32
  33 /*
  34  * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect.
  35  */
  36 static unsigned int __init estimate_cpu_frequency(void)
  37 {
  38         unsigned int prid = read_c0_prid() & 0xffff00;
  39         unsigned int tick = 0;
  40         unsigned int freq;
  41         unsigned int orig;
  42         unsigned long flags;
  43
  44         local_irq_save(flags);
  45
  46         orig = readl(status_reg) & 0x2;               /* get original sample */
  47         /* wait for transition */
  48         while ((readl(status_reg) & 0x2) == orig)
  49                 ;
  50         orig = orig ^ 0x2;                            /* flip the bit */
  51
  52         write_c0_count(0);
  53
  54         /* wait 1 second (the sampling clock transitions every 10ms) */
  55         while (tick < 100) {
  56                 /* wait for transition */
  57                 while ((readl(status_reg) & 0x2) == orig)
  58                         ;
  59                 orig = orig ^ 0x2;                            /* flip the bit */
  60                 tick++;
  61         }
  62
  63         freq = read_c0_count();
  64
  65         local_irq_restore(flags);
  66
  67         mips_hpt_frequency = freq;
  68
  69         /* Adjust for processor */
  70         if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
  71                 (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
  72                 freq *= 2;
  73
  74         freq += 5000;        /* rounding */
  75         freq -= freq%10000;
  76
  77         return freq ;
  78 }
  79
  80 void read_persistent_clock(struct timespec *ts)
  81 {
  82         ts->tv_sec = 0;
  83         ts->tv_nsec = 0;
  84 }
  85
  86 static void __init plat_perf_setup(void)
  87 {
  88         if (cp0_perfcount_irq >= 0) {
  89                 if (cpu_has_vint)
  90                         set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
  91                 mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
  92         }
  93 }
  94
  95 unsigned int __cpuinit get_c0_compare_int(void)
  96 {
  97         if (cpu_has_vint)
  98                 set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
  99         mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
 100         return mips_cpu_timer_irq;
 101 }
 102
 103 void __init plat_time_init(void)
 104 {
 105         unsigned int est_freq;
 106
 107         est_freq = estimate_cpu_frequency();
 108
 109         pr_debug("CPU frequency %d.%02d MHz\n", (est_freq / 1000000),
 110                 (est_freq % 1000000) * 100 / 1000000);
 111
 112         cpu_khz = est_freq / 1000;
 113
 114         mips_scroll_message();
 115
 116         plat_perf_setup();
 117 }