release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/mti-malta/malta-amon.c

   1 /*
   2  * Copyright (C) 2007, 2011 MIPS Technologies, Inc.
   3  *      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  * Arbitrary Monitor interface
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/smp.h>
  24
  25 #include <asm/addrspace.h>
  26 #include <asm/mips-boards/launch.h>
  27 #include <asm/mipsmtregs.h>
  28
  29 int amon_cpu_avail(int cpu)
  30 {
  31         struct cpulaunch *launch = (struct cpulaunch *)CKSEG0ADDR(CPULAUNCH);
  32
  33         if (cpu < 0 || cpu >= NCPULAUNCH) {
  34                 pr_debug("avail: cpu%d is out of range\n", cpu);
  35                 return 0;
  36         }
  37
  38         launch += cpu;
  39         if (!(launch->flags & LAUNCH_FREADY)) {
  40                 pr_debug("avail: cpu%d is not ready\n", cpu);
  41                 return 0;
  42         }
  43         if (launch->flags & (LAUNCH_FGO|LAUNCH_FGONE)) {
  44                 pr_debug("avail: too late.. cpu%d is already gone\n", cpu);
  45                 return 0;
  46         }
  47
  48         return 1;
  49 }
  50
  51 void amon_cpu_start(int cpu,
  52                     unsigned long pc, unsigned long sp,
  53                     unsigned long gp, unsigned long a0)
  54 {
  55         volatile struct cpulaunch *launch =
  56                 (struct cpulaunch  *)CKSEG0ADDR(CPULAUNCH);
  57
  58         if (!amon_cpu_avail(cpu))
  59                 return;
  60         if (cpu == smp_processor_id()) {
  61                 pr_debug("launch: I am cpu%d!\n", cpu);
  62                 return;
  63         }
  64         launch += cpu;
  65
  66         pr_debug("launch: starting cpu%d\n", cpu);
  67
  68         launch->pc = pc;
  69         launch->gp = gp;
  70         launch->sp = sp;
  71         launch->a0 = a0;
  72
  73         smp_wmb();              /* Target must see parameters before go */
  74         launch->flags |= LAUNCH_FGO;
  75         smp_wmb();              /* Target must see go before we poll  */
  76         while ((launch->flags & LAUNCH_FGONE) == 0)
  77                 ;
  78         smp_rmb();              /* Target will be updating flags soon */
  79         pr_debug("launch: cpu%d gone!\n", cpu);
  80 }
  81
  82 /*
  83  * Restart the CPU ready for amon_cpu_start again
  84  * A bit of a hack... it duplicates the CPU startup code that
  85  * lives somewhere in the boot monitor.
  86  */
  87 void amon_cpu_dead(void)
  88 {
  89         struct cpulaunch *launch;
  90         unsigned int r0;
  91         int cpufreq;
  92
  93         launch = (struct cpulaunch *)CKSEG0ADDR(CPULAUNCH);
  94         launch += smp_processor_id();
  95
  96         launch->pc = 0;
  97         launch->gp = 0;
  98         launch->sp = 0;
  99         launch->a0 = 0;
 100         launch->flags = LAUNCH_FREADY;
 101
 102         cpufreq = 500000000;
 103
 104         __asm__ __volatile__ (
 105         "       .set    push\n\t"
 106         "       .set    noreorder\n\t"
 107         "1:\n\t"
 108         "       lw      %[r0],%[LAUNCH_FLAGS](%[launch])\n\t"
 109         "       andi    %[r0],%[FGO]\n\t"
 110         "       bnez    %[r0],1f\n\t"
 111         "        nop\n\t"
 112         "       mfc0    %[r0],$9\n\t"   /* Read Count */
 113         "       addu    %[r0],%[waitperiod]\n\t"
 114         "       mtc0    %[r0],$11\n\t"  /* Write Compare */
 115         "       wait\n\t"
 116         "       b       1b\n\t"
 117         "        nop\n\t"
 118         "1:     lw      $ra,%[LAUNCH_PC](%[launch])\n\t"
 119         "       lw      $gp,%[LAUNCH_GP](%[launch])\n\t"
 120         "       lw      $sp,%[LAUNCH_SP](%[launch])\n\t"
 121         "       lw      $a0,%[LAUNCH_A0](%[launch])\n\t"
 122         "       move    $a1,$zero\n\t"
 123         "       move    $a2,$zero\n\t"
 124         "       move    $a3,$zero\n\t"
 125         "       lw      %[r0],%[LAUNCH_FLAGS](%[launch])\n\t"
 126         "       ori     %[r0],%[FGONE]\n\t"
 127         "       jr      $ra\n\t"
 128         "        sw     %[r0],%[LAUNCH_FLAGS](%[launch])\n\t"
 129         "       .set    pop\n\t"
 130         : [r0] "=&r" (r0)
 131         : [launch] "r" (launch),
 132           [FGONE] "i" (LAUNCH_FGONE),
 133           [FGO] "i" (LAUNCH_FGO),
 134           [LAUNCH_PC] "i" (offsetof(struct cpulaunch, pc)),
 135           [LAUNCH_GP] "i" (offsetof(struct cpulaunch, gp)),
 136           [LAUNCH_SP] "i" (offsetof(struct cpulaunch, sp)),
 137           [LAUNCH_A0] "i" (offsetof(struct cpulaunch, a0)),
 138           [LAUNCH_FLAGS] "i" (offsetof(struct cpulaunch, flags)),
 139           [waitperiod] "i" ((cpufreq / 2) / 100)        /* delay of ~10ms  */
 140         : "ra","a0","a1","a2","a3","sp" /* ,"gp" */
 141         );
 142 }