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  * Copyright (C) 2009, 2012 Cavium, Inc.
   8  */
   9 #include <linux/clocksource.h>
  10 #include <linux/export.h>
  11 #include <linux/init.h>
  12 #include <linux/smp.h>
  13
  14 #include <asm/cpu-info.h>
  15 #include <asm/time.h>
  16
  17 #include <asm/octeon/octeon.h>
  18 #include <asm/octeon/cvmx-ipd-defs.h>
  19 #include <asm/octeon/cvmx-mio-defs.h>
  20
  21
  22 static u64 f;
  23 static u64 rdiv;
  24 static u64 sdiv;
  25 static u64 octeon_udelay_factor;
  26 static u64 octeon_ndelay_factor;
  27
  28 void __init octeon_setup_delays(void)
  29 {
  30         octeon_udelay_factor = octeon_get_clock_rate() / 1000000;
  31         /*
  32          * For __ndelay we divide by 2^16, so the factor is multiplied
  33          * by the same amount.
  34          */
  35         octeon_ndelay_factor = (octeon_udelay_factor * 0x10000ull) / 1000ull;
  36
  37         preset_lpj = octeon_get_clock_rate() / HZ;
  38
  39         if (current_cpu_type() == CPU_CAVIUM_OCTEON2) {
  40                 union cvmx_mio_rst_boot rst_boot;
  41                 rst_boot.u64 = cvmx_read_csr(CVMX_MIO_RST_BOOT);
  42                 rdiv = rst_boot.s.c_mul;        /* CPU clock */
  43                 sdiv = rst_boot.s.pnr_mul;      /* I/O clock */
  44                 f = (0x8000000000000000ull / sdiv) * 2;
  45         }
  46 }
  47
  48 /*
  49  * Set the current core's cvmcount counter to the value of the
  50  * IPD_CLK_COUNT.  We do this on all cores as they are brought
  51  * on-line.  This allows for a read from a local cpu register to
  52  * access a synchronized counter.
  53  *
  54  * On CPU_CAVIUM_OCTEON2 the IPD_CLK_COUNT is scaled by rdiv/sdiv.
  55  */
  56 void octeon_init_cvmcount(void)
  57 {
  58         unsigned long flags;
  59         unsigned loops = 2;
  60
  61         /* Clobber loops so GCC will not unroll the following while loop. */
  62         asm("" : "+r" (loops));
  63
  64         local_irq_save(flags);
  65         /*
  66          * Loop several times so we are executing from the cache,
  67          * which should give more deterministic timing.
  68          */
  69         while (loops--) {
  70                 u64 ipd_clk_count = cvmx_read_csr(CVMX_IPD_CLK_COUNT);
  71                 if (rdiv != 0) {
  72                         ipd_clk_count *= rdiv;
  73                         if (f != 0) {
  74                                 asm("dmultu\t%[cnt],%[f]\n\t"
  75                                     "mfhi\t%[cnt]"
  76                                     : [cnt] "+r" (ipd_clk_count)
  77                                     : [f] "r" (f)
  78                                     : "hi", "lo");
  79                         }
  80                 }
  81                 write_c0_cvmcount(ipd_clk_count);
  82         }
  83         local_irq_restore(flags);
  84 }
  85
  86 static cycle_t octeon_cvmcount_read(struct clocksource *cs)
  87 {
  88         return read_c0_cvmcount();
  89 }
  90
  91 static struct clocksource clocksource_mips = {
  92         .name           = "OCTEON_CVMCOUNT",
  93         .read           = octeon_cvmcount_read,
  94         .mask           = CLOCKSOURCE_MASK(64),
  95         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  96 };
  97
  98 unsigned long long notrace sched_clock(void)
  99 {
 100         /* 64-bit arithmatic can overflow, so use 128-bit.  */
 101         u64 t1, t2, t3;
 102         unsigned long long rv;
 103         u64 mult = clocksource_mips.mult;
 104         u64 shift = clocksource_mips.shift;
 105         u64 cnt = read_c0_cvmcount();
 106
 107         asm (
 108                 "dmultu\t%[cnt],%[mult]\n\t"
 109                 "nor\t%[t1],$0,%[shift]\n\t"
 110                 "mfhi\t%[t2]\n\t"
 111                 "mflo\t%[t3]\n\t"
 112                 "dsll\t%[t2],%[t2],1\n\t"
 113                 "dsrlv\t%[rv],%[t3],%[shift]\n\t"
 114                 "dsllv\t%[t1],%[t2],%[t1]\n\t"
 115                 "or\t%[rv],%[t1],%[rv]\n\t"
 116                 : [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3)
 117                 : [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift)
 118                 : "hi", "lo");
 119         return rv;
 120 }
 121
 122 void __init plat_time_init(void)
 123 {
 124         clocksource_mips.rating = 300;
 125         clocksource_register_hz(&clocksource_mips, octeon_get_clock_rate());
 126 }
 127
 128 void __udelay(unsigned long us)
 129 {
 130         u64 cur, end, inc;
 131
 132         cur = read_c0_cvmcount();
 133
 134         inc = us * octeon_udelay_factor;
 135         end = cur + inc;
 136
 137         while (end > cur)
 138                 cur = read_c0_cvmcount();
 139 }
 140 EXPORT_SYMBOL(__udelay);
 141
 142 void __ndelay(unsigned long ns)
 143 {
 144         u64 cur, end, inc;
 145
 146         cur = read_c0_cvmcount();
 147
 148         inc = ((ns * octeon_ndelay_factor) >> 16);
 149         end = cur + inc;
 150
 151         while (end > cur)
 152                 cur = read_c0_cvmcount();
 153 }
 154 EXPORT_SYMBOL(__ndelay);
 155
 156 void __delay(unsigned long loops)
 157 {
 158         u64 cur, end;
 159
 160         cur = read_c0_cvmcount();
 161         end = cur + loops;
 162
 163         while (end > cur)
 164                 cur = read_c0_cvmcount();
 165 }
 166 EXPORT_SYMBOL(__delay);
 167
 168
 169 /**
 170  * octeon_io_clk_delay - wait for a given number of io clock cycles to pass.
 171  *
 172  * We scale the wait by the clock ratio, and then wait for the
 173  * corresponding number of core clocks.
 174  *
 175  * @count: The number of clocks to wait.
 176  */
 177 void octeon_io_clk_delay(unsigned long count)
 178 {
 179         u64 cur, end;
 180
 181         cur = read_c0_cvmcount();
 182         if (rdiv != 0) {
 183                 end = count * rdiv;
 184                 if (f != 0) {
 185                         asm("dmultu\t%[cnt],%[f]\n\t"
 186                                 "mfhi\t%[cnt]"
 187                                 : [cnt] "+r" (end)
 188                                 : [f] "r" (f)
 189                                 : "hi", "lo");
 190                 }
 191                 end = cur + end;
 192         } else {
 193                 end = cur + count;
 194         }
 195         while (end > cur)
 196                 cur = read_c0_cvmcount();
 197 }
 198 EXPORT_SYMBOL(octeon_io_clk_delay);