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