release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/cavium-octeon/csrc-octeon.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) 2007 by Ralf Baechle
   7  */
   8 #include <linux/clocksource.h>
   9 #include <linux/init.h>
  10
  11 #include <asm/time.h>
  12
  13 #include <asm/octeon/octeon.h>
  14 #include <asm/octeon/cvmx-ipd-defs.h>
  15
  16 /*
  17  * Set the current core's cvmcount counter to the value of the
  18  * IPD_CLK_COUNT.  We do this on all cores as they are brought
  19  * on-line.  This allows for a read from a local cpu register to
  20  * access a synchronized counter.
  21  *
  22  */
  23 void octeon_init_cvmcount(void)
  24 {
  25         unsigned long flags;
  26         unsigned loops = 2;
  27
  28         /* Clobber loops so GCC will not unroll the following while loop. */
  29         asm("" : "+r" (loops));
  30
  31         local_irq_save(flags);
  32         /*
  33          * Loop several times so we are executing from the cache,
  34          * which should give more deterministic timing.
  35          */
  36         while (loops--)
  37                 write_c0_cvmcount(cvmx_read_csr(CVMX_IPD_CLK_COUNT));
  38         local_irq_restore(flags);
  39 }
  40
  41 static cycle_t octeon_cvmcount_read(struct clocksource *cs)
  42 {
  43         return read_c0_cvmcount();
  44 }
  45
  46 static struct clocksource clocksource_mips = {
  47         .name           = "OCTEON_CVMCOUNT",
  48         .read           = octeon_cvmcount_read,
  49         .mask           = CLOCKSOURCE_MASK(64),
  50         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  51 };
  52
  53 unsigned long long notrace sched_clock(void)
  54 {
  55         /* 64-bit arithmatic can overflow, so use 128-bit.  */
  56         u64 t1, t2, t3;
  57         unsigned long long rv;
  58         u64 mult = clocksource_mips.mult;
  59         u64 shift = clocksource_mips.shift;
  60         u64 cnt = read_c0_cvmcount();
  61
  62         asm (
  63                 "dmultu\t%[cnt],%[mult]\n\t"
  64                 "nor\t%[t1],$0,%[shift]\n\t"
  65                 "mfhi\t%[t2]\n\t"
  66                 "mflo\t%[t3]\n\t"
  67                 "dsll\t%[t2],%[t2],1\n\t"
  68                 "dsrlv\t%[rv],%[t3],%[shift]\n\t"
  69                 "dsllv\t%[t1],%[t2],%[t1]\n\t"
  70                 "or\t%[rv],%[t1],%[rv]\n\t"
  71                 : [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3)
  72                 : [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift)
  73                 : "hi", "lo");
  74         return rv;
  75 }
  76
  77 void __init plat_time_init(void)
  78 {
  79         clocksource_mips.rating = 300;
  80         clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
  81         clocksource_register(&clocksource_mips);
  82 }
  83
  84 static u64 octeon_udelay_factor;
  85 static u64 octeon_ndelay_factor;
  86
  87 void __init octeon_setup_delays(void)
  88 {
  89         octeon_udelay_factor = octeon_get_clock_rate() / 1000000;
  90         /*
  91          * For __ndelay we divide by 2^16, so the factor is multiplied
  92          * by the same amount.
  93          */
  94         octeon_ndelay_factor = (octeon_udelay_factor * 0x10000ull) / 1000ull;
  95
  96         preset_lpj = octeon_get_clock_rate() / HZ;
  97 }
  98
  99 void __udelay(unsigned long us)
 100 {
 101         u64 cur, end, inc;
 102
 103         cur = read_c0_cvmcount();
 104
 105         inc = us * octeon_udelay_factor;
 106         end = cur + inc;
 107
 108         while (end > cur)
 109                 cur = read_c0_cvmcount();
 110 }
 111 EXPORT_SYMBOL(__udelay);
 112
 113 void __ndelay(unsigned long ns)
 114 {
 115         u64 cur, end, inc;
 116
 117         cur = read_c0_cvmcount();
 118
 119         inc = ((ns * octeon_ndelay_factor) >> 16);
 120         end = cur + inc;
 121
 122         while (end > cur)
 123                 cur = read_c0_cvmcount();
 124 }
 125 EXPORT_SYMBOL(__ndelay);
 126
 127 void __delay(unsigned long loops)
 128 {
 129         u64 cur, end;
 130
 131         cur = read_c0_cvmcount();
 132         end = cur + loops;
 133
 134         while (end > cur)
 135                 cur = read_c0_cvmcount();
 136 }
 137 EXPORT_SYMBOL(__delay);