release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/mti-sead3/sead3-time.c

   1 /*
   2  * Carsten Langgaard, carstenl@mips.com
   3  * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
   4  *
   5  *  This program is free software; you can distribute it and/or modify it
   6  *  under the terms of the GNU General Public License (Version 2) as
   7  *  published by the Free Software Foundation.
   8  *
   9  *  This program is distributed in the hope it will be useful, but WITHOUT
  10  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  *  for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License along
  15  *  with this program; if not, write to the Free Software Foundation, Inc.,
  16  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  17  *
  18  * Setting up the clock on the MIPS boards.
  19  */
  20
  21 #include <linux/types.h>
  22 #include <linux/init.h>
  23 #include <linux/kernel_stat.h>
  24 #include <linux/sched.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/time.h>
  28 #include <linux/timex.h>
  29
  30 #include <asm/mipsregs.h>
  31 #include <asm/mipsmtregs.h>
  32 #include <asm/hardirq.h>
  33 #include <asm/i8253.h>
  34 #include <asm/irq.h>
  35 #include <asm/div64.h>
  36 #include <asm/cpu.h>
  37 #include <asm/time.h>
  38 #include <asm/msc01_ic.h>
  39
  40 #include <asm/mips-boards/generic.h>
  41 #include <asm/mips-boards/prom.h>
  42
  43 unsigned long cpu_khz;
  44
  45 static int mips_cpu_timer_irq;
  46 static int mips_cpu_perf_irq;
  47 extern int cp0_perfcount_irq;
  48
  49 static void mips_timer_dispatch(void)
  50 {
  51         do_IRQ(mips_cpu_timer_irq);
  52 }
  53
  54 static void mips_perf_dispatch(void)
  55 {
  56         do_IRQ(mips_cpu_perf_irq);
  57 }
  58
  59 static void __iomem *status_reg   = (void __iomem *)0xbf000410;
  60
  61 /*
  62  * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
  63  */
  64 static unsigned int __init estimate_cpu_frequency(void)
  65 {
  66         unsigned int prid = read_c0_prid() & 0xffff00;
  67         unsigned int tick = 0;
  68         unsigned int freq;
  69         unsigned int orig;
  70         unsigned long flags;
  71
  72         local_irq_save(flags);
  73
  74         orig = readl(status_reg) & 0x2;               /* get original sample */
  75         /* wait for transition */
  76         while ((readl(status_reg) & 0x2) == orig)
  77                 ;
  78         orig = orig ^ 0x2;                            /* flip the bit */
  79
  80         write_c0_count(0);
  81
  82         /* wait 1 second (the sampling clock transitions every 10ms) */
  83         while (tick < 100) {
  84                 /* wait for transition */
  85                 while ((readl(status_reg) & 0x2) == orig)
  86                         ;
  87                 orig = orig ^ 0x2;                            /* flip the bit */
  88                 tick++;
  89         }
  90
  91         freq = read_c0_count();
  92
  93         local_irq_restore(flags);
  94
  95         mips_hpt_frequency = freq;
  96
  97         /* Adjust for processor */
  98         if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
  99                 (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
 100                 freq *= 2;
 101
 102         freq += 5000;        /* rounding */
 103         freq -= freq%10000;
 104
 105         return freq ;
 106 }
 107
 108 void read_persistent_clock(struct timespec *ts)
 109 {
 110         ts->tv_sec = 0;
 111         ts->tv_nsec = 0;
 112 }
 113
 114 static void __init plat_perf_setup(void)
 115 {
 116         if (cp0_perfcount_irq >= 0) {
 117                 if (cpu_has_vint)
 118                         set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
 119                 mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
 120         }
 121 }
 122
 123 unsigned int __cpuinit get_c0_compare_int(void)
 124 {
 125         if (cpu_has_vint)
 126                 set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
 127         mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
 128         return mips_cpu_timer_irq;
 129 }
 130
 131 void __init plat_time_init(void)
 132 {
 133         unsigned int est_freq;
 134
 135         est_freq = estimate_cpu_frequency();
 136
 137         printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
 138                (est_freq%1000000)*100/1000000);
 139
 140         cpu_khz = est_freq / 1000;
 141
 142         mips_scroll_message();
 143
 144         plat_perf_setup();
 145 }