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 /*
  58  * The following aren't currently used.
  59  */
  60 void (*pm_idle)(void);
  61
  62 extern void default_idle(void);
  63
  64 void (*pm_power_off)(void);
  65 EXPORT_SYMBOL(pm_power_off);
  66
  67 /*
  68  * The idle thread. There's no useful work to be
  69  * done, so just try to conserve power and have a
  70  * low exit latency (ie sit in a loop waiting for
  71  * somebody to say that they'd like to reschedule)
  72  */
  73
  74 void cpu_idle (void)
  75 {
  76         /* endless idle loop with no priority at all */
  77         while (1) {
  78                 rcu_idle_enter();
  79                 while (!need_resched()) {
  80                         void (*idle)(void);
  81                         /*
  82                          * Mark this as an RCU critical section so that
  83                          * synchronize_kernel() in the unload path waits
  84                          * for our completion.
  85                          */
  86                         idle = pm_idle;
  87                         if (!idle)
  88                                 idle = default_idle;
  89                         idle();
  90                 }
  91                 rcu_idle_exit();
  92                 schedule_preempt_disabled();
  93         }
  94 }
  95
  96 void hard_reset_now (void);
  97
  98 void machine_restart(char *cmd)
  99 {
 100         hard_reset_now();
 101 }
 102
 103 /*
 104  * Similar to machine_power_off, but don't shut off power.  Add code
 105  * here to freeze the system for e.g. post-mortem debug purpose when
 106  * possible.  This halt has nothing to do with the idle halt.
 107  */
 108
 109 void machine_halt(void)
 110 {
 111 }
 112
 113 /* If or when software power-off is implemented, add code here.  */
 114
 115 void machine_power_off(void)
 116 {
 117 }
 118
 119 /*
 120  * When a process does an "exec", machine state like FPU and debug
 121  * registers need to be reset.  This is a hook function for that.
 122  * Currently we don't have any such state to reset, so this is empty.
 123  */
 124
 125 void flush_thread(void)
 126 {
 127 }
 128
 129 /* Fill in the fpu structure for a core dump. */
 130 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 131 {
 132         return 0;
 133 }