arch/cris/kernel/process.c

   1 /*
   2  *  linux/arch/cris/kernel/process.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *  Copyright (C) 2000-2002  Axis Communications AB
   6  *
   7  *  Authors:   Bjorn Wesen (bjornw@axis.com)
   8  *
   9  */
  10
  11 /*
  12  * This file handles the architecture-dependent parts of process handling..
  13  */
  14
  15 #include <linux/atomic.h>
  16 #include <asm/pgtable.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/irq.h>
  19 #include <linux/module.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/init_task.h>
  22 #include <linux/sched.h>
  23 #include <linux/fs.h>
  24 #include <linux/user.h>
  25 #include <linux/elfcore.h>
  26 #include <linux/mqueue.h>
  27 #include <linux/reboot.h>
  28 #include <linux/rcupdate.h>
  29
  30 //#define DEBUG
  31
  32 /*
  33  * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  34  * there would ever be a halt sequence (for power save when idle) with
  35  * some largish delay when halting or resuming *and* a driver that can't
  36  * afford that delay.  The hlt_counter would then be checked before
  37  * executing the halt sequence, and the driver marks the unhaltable
  38  * region by enable_hlt/disable_hlt.
  39  */
  40
  41 int cris_hlt_counter=0;
  42
  43 void disable_hlt(void)
  44 {
  45         cris_hlt_counter++;
  46 }
  47
  48 EXPORT_SYMBOL(disable_hlt);
  49
  50 void enable_hlt(void)
  51 {
  52         cris_hlt_counter--;
  53 }
  54
  55 EXPORT_SYMBOL(enable_hlt);
  56
  57 extern void default_idle(void);
  58
  59 void (*pm_power_off)(void);
  60 EXPORT_SYMBOL(pm_power_off);
  61
  62 /*
  63  * The idle thread. There's no useful work to be
  64  * done, so just try to conserve power and have a
  65  * low exit latency (ie sit in a loop waiting for
  66  * somebody to say that they'd like to reschedule)
  67  */
  68
  69 void cpu_idle (void)
  70 {
  71         /* endless idle loop with no priority at all */
  72         while (1) {
  73                 rcu_idle_enter();
  74                 while (!need_resched()) {
  75                         /*
  76                          * Mark this as an RCU critical section so that
  77                          * synchronize_kernel() in the unload path waits
  78                          * for our completion.
  79                          */
  80                         default_idle();
  81                 }
  82                 rcu_idle_exit();
  83                 schedule_preempt_disabled();
  84         }
  85 }
  86
  87 void hard_reset_now (void);
  88
  89 void machine_restart(char *cmd)
  90 {
  91         hard_reset_now();
  92 }
  93
  94 /*
  95  * Similar to machine_power_off, but don't shut off power.  Add code
  96  * here to freeze the system for e.g. post-mortem debug purpose when
  97  * possible.  This halt has nothing to do with the idle halt.
  98  */
  99
 100 void machine_halt(void)
 101 {
 102 }
 103
 104 /* If or when software power-off is implemented, add code here.  */
 105
 106 void machine_power_off(void)
 107 {
 108 }
 109
 110 /*
 111  * When a process does an "exec", machine state like FPU and debug
 112  * registers need to be reset.  This is a hook function for that.
 113  * Currently we don't have any such state to reset, so this is empty.
 114  */
 115
 116 void flush_thread(void)
 117 {
 118 }
 119
 120 /* Fill in the fpu structure for a core dump. */
 121 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 122 {
 123         return 0;
 124 }