kernel/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/cpu-type.h>
  16 #include <asm/time.h>
  17
  18 #include <asm/octeon/octeon.h>
  19 #include <asm/octeon/cvmx-ipd-defs.h>
  20 #include <asm/octeon/cvmx-mio-defs.h>
  21 #include <asm/octeon/cvmx-rst-defs.h>
  22
  23 static u64 f;
  24 static u64 rdiv;
  25 static u64 sdiv;
  26 static u64 octeon_udelay_factor;
  27 static u64 octeon_ndelay_factor;
  28
  29 void __init octeon_setup_delays(void)
  30 {
  31         octeon_udelay_factor = octeon_get_clock_rate() / 1000000;
  32         /*
  33          * For __ndelay we divide by 2^16, so the factor is multiplied
  34          * by the same amount.
  35          */
  36         octeon_ndelay_factor = (octeon_udelay_factor * 0x10000ull) / 1000ull;
  37
  38         preset_lpj = octeon_get_clock_rate() / HZ;
  39
  40         if (current_cpu_type() == CPU_CAVIUM_OCTEON2) {
  41                 union cvmx_mio_rst_boot rst_boot;
  42
  43                 rst_boot.u64 = cvmx_read_csr(CVMX_MIO_RST_BOOT);
  44                 rdiv = rst_boot.s.c_mul;        /* CPU clock */
  45                 sdiv = rst_boot.s.pnr_mul;      /* I/O clock */
  46                 f = (0x8000000000000000ull / sdiv) * 2;
  47         } else if (current_cpu_type() == CPU_CAVIUM_OCTEON3) {
  48                 union cvmx_rst_boot rst_boot;
  49
  50                 rst_boot.u64 = cvmx_read_csr(CVMX_RST_BOOT);
  51                 rdiv = rst_boot.s.c_mul;        /* CPU clock */
  52                 sdiv = rst_boot.s.pnr_mul;      /* I/O clock */
  53                 f = (0x8000000000000000ull / sdiv) * 2;
  54         }
  55
  56 }
  57
  58 /*
  59  * Set the current core's cvmcount counter to the value of the
  60  * IPD_CLK_COUNT.  We do this on all cores as they are brought
  61  * on-line.  This allows for a read from a local cpu register to
  62  * access a synchronized counter.
  63  *
  64  * On CPU_CAVIUM_OCTEON2 the IPD_CLK_COUNT is scaled by rdiv/sdiv.
  65  */
  66 void octeon_init_cvmcount(void)
  67 {
  68         unsigned long flags;
  69         unsigned loops = 2;
  70
  71         /* Clobber loops so GCC will not unroll the following while loop. */
  72         asm("" : "+r" (loops));
  73
  74         local_irq_save(flags);
  75         /*
  76          * Loop several times so we are executing from the cache,
  77          * which should give more deterministic timing.
  78          */
  79         while (loops--) {
  80                 u64 ipd_clk_count = cvmx_read_csr(CVMX_IPD_CLK_COUNT);
  81                 if (rdiv != 0) {
  82                         ipd_clk_count *= rdiv;
  83                         if (f != 0) {
  84                                 asm("dmultu\t%[cnt],%[f]\n\t"
  85                                     "mfhi\t%[cnt]"
  86                                     : [cnt] "+r" (ipd_clk_count)
  87                                     : [f] "r" (f)
  88                                     : "hi", "lo");
  89                         }
  90                 }
  91                 write_c0_cvmcount(ipd_clk_count);
  92         }
  93         local_irq_restore(flags);
  94 }
  95
  96 static cycle_t octeon_cvmcount_read(struct clocksource *cs)
  97 {
  98         return read_c0_cvmcount();
  99 }
 100
 101 static struct clocksource clocksource_mips = {
 102         .name           = "OCTEON_CVMCOUNT",
 103         .read           = octeon_cvmcount_read,
 104         .mask           = CLOCKSOURCE_MASK(64),
 105         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 106 };
 107
 108 unsigned long long notrace sched_clock(void)
 109 {
 110         /* 64-bit arithmatic can overflow, so use 128-bit.  */
 111         u64 t1, t2, t3;
 112         unsigned long long rv;
 113         u64 mult = clocksource_mips.mult;
 114         u64 shift = clocksource_mips.shift;
 115         u64 cnt = read_c0_cvmcount();
 116
 117         asm (
 118                 "dmultu\t%[cnt],%[mult]\n\t"
 119                 "nor\t%[t1],$0,%[shift]\n\t"
 120                 "mfhi\t%[t2]\n\t"
 121                 "mflo\t%[t3]\n\t"
 122                 "dsll\t%[t2],%[t2],1\n\t"
 123                 "dsrlv\t%[rv],%[t3],%[shift]\n\t"
 124                 "dsllv\t%[t1],%[t2],%[t1]\n\t"
 125                 "or\t%[rv],%[t1],%[rv]\n\t"
 126                 : [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3)
 127                 : [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift)
 128                 : "hi", "lo");
 129         return rv;
 130 }
 131
 132 void __init plat_time_init(void)
 133 {
 134         clocksource_mips.rating = 300;
 135         clocksource_register_hz(&clocksource_mips, octeon_get_clock_rate());
 136 }
 137
 138 void __udelay(unsigned long us)
 139 {
 140         u64 cur, end, inc;
 141
 142         cur = read_c0_cvmcount();
 143
 144         inc = us * octeon_udelay_factor;
 145         end = cur + inc;
 146
 147         while (end > cur)
 148                 cur = read_c0_cvmcount();
 149 }
 150 EXPORT_SYMBOL(__udelay);
 151
 152 void __ndelay(unsigned long ns)
 153 {
 154         u64 cur, end, inc;
 155
 156         cur = read_c0_cvmcount();
 157
 158         inc = ((ns * octeon_ndelay_factor) >> 16);
 159         end = cur + inc;
 160
 161         while (end > cur)
 162                 cur = read_c0_cvmcount();
 163 }
 164 EXPORT_SYMBOL(__ndelay);
 165
 166 void __delay(unsigned long loops)
 167 {
 168         u64 cur, end;
 169
 170         cur = read_c0_cvmcount();
 171         end = cur + loops;
 172
 173         while (end > cur)
 174                 cur = read_c0_cvmcount();
 175 }
 176 EXPORT_SYMBOL(__delay);
 177
 178
 179 /**
 180  * octeon_io_clk_delay - wait for a given number of io clock cycles to pass.
 181  *
 182  * We scale the wait by the clock ratio, and then wait for the
 183  * corresponding number of core clocks.
 184  *
 185  * @count: The number of clocks to wait.
 186  */
 187 void octeon_io_clk_delay(unsigned long count)
 188 {
 189         u64 cur, end;
 190
 191         cur = read_c0_cvmcount();
 192         if (rdiv != 0) {
 193                 end = count * rdiv;
 194                 if (f != 0) {
 195                         asm("dmultu\t%[cnt],%[f]\n\t"
 196                                 "mfhi\t%[cnt]"
 197                                 : [cnt] "+r" (end)
 198                                 : [f] "r" (f)
 199                                 : "hi", "lo");
 200                 }
 201                 end = cur + end;
 202         } else {
 203                 end = cur + count;
 204         }
 205         while (end > cur)
 206                 cur = read_c0_cvmcount();
 207 }
 208 EXPORT_SYMBOL(octeon_io_clk_delay);