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 #include <linux/irqchip/mips-gic.h>
  10
  11 #include <asm/cpu.h>
  12 #include <asm/setup.h>
  13 #include <asm/time.h>
  14 #include <asm/irq.h>
  15 #include <asm/mips-boards/generic.h>
  16
  17 static void __iomem *status_reg = (void __iomem *)0xbf000410;
  18
  19 /*
  20  * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect.
  21  */
  22 static unsigned int __init estimate_cpu_frequency(void)
  23 {
  24         unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
  25         unsigned int tick = 0;
  26         unsigned int freq;
  27         unsigned int orig;
  28         unsigned long flags;
  29
  30         local_irq_save(flags);
  31
  32         orig = readl(status_reg) & 0x2;               /* get original sample */
  33         /* wait for transition */
  34         while ((readl(status_reg) & 0x2) == orig)
  35                 ;
  36         orig = orig ^ 0x2;                            /* flip the bit */
  37
  38         write_c0_count(0);
  39
  40         /* wait 1 second (the sampling clock transitions every 10ms) */
  41         while (tick < 100) {
  42                 /* wait for transition */
  43                 while ((readl(status_reg) & 0x2) == orig)
  44                         ;
  45                 orig = orig ^ 0x2;                            /* flip the bit */
  46                 tick++;
  47         }
  48
  49         freq = read_c0_count();
  50
  51         local_irq_restore(flags);
  52
  53         mips_hpt_frequency = freq;
  54
  55         /* Adjust for processor */
  56         if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
  57                 (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
  58                 freq *= 2;
  59
  60         freq += 5000;        /* rounding */
  61         freq -= freq%10000;
  62
  63         return freq ;
  64 }
  65
  66 void read_persistent_clock(struct timespec *ts)
  67 {
  68         ts->tv_sec = 0;
  69         ts->tv_nsec = 0;
  70 }
  71
  72 int get_c0_perfcount_int(void)
  73 {
  74         if (gic_present)
  75                 return gic_get_c0_perfcount_int();
  76         if (cp0_perfcount_irq >= 0)
  77                 return MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
  78         return -1;
  79 }
  80 EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
  81
  82 unsigned int get_c0_compare_int(void)
  83 {
  84         if (gic_present)
  85                 return gic_get_c0_compare_int();
  86         return MIPS_CPU_IRQ_BASE + cp0_compare_irq;
  87 }
  88
  89 void __init plat_time_init(void)
  90 {
  91         unsigned int est_freq;
  92
  93         est_freq = estimate_cpu_frequency();
  94
  95         pr_debug("CPU frequency %d.%02d MHz\n", (est_freq / 1000000),
  96                 (est_freq % 1000000) * 100 / 1000000);
  97
  98         mips_scroll_message();
  99 }