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 void __init plat_time_init(void)
  54 {
  55         clocksource_mips.rating = 300;
  56         clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
  57         clocksource_register(&clocksource_mips);
  58 }