linux/arch/cris/kernel/process.c
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   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 <asm/atomic.h>
  16#include <asm/pgtable.h>
  17#include <asm/uaccess.h>
  18#include <asm/irq.h>
  19#include <asm/system.h>
  20#include <linux/module.h>
  21#include <linux/spinlock.h>
  22#include <linux/init_task.h>
  23#include <linux/sched.h>
  24#include <linux/fs.h>
  25#include <linux/user.h>
  26#include <linux/elfcore.h>
  27#include <linux/mqueue.h>
  28#include <linux/reboot.h>
  29
  30//#define DEBUG
  31
  32/*
  33 * Initial task structure. Make this a per-architecture thing,
  34 * because different architectures tend to have different
  35 * alignment requirements and potentially different initial
  36 * setup.
  37 */
  38
  39static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  40static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  41/*
  42 * Initial thread structure.
  43 *
  44 * We need to make sure that this is 8192-byte aligned due to the
  45 * way process stacks are handled. This is done by having a special
  46 * "init_task" linker map entry..
  47 */
  48union thread_union init_thread_union __init_task_data =
  49        { INIT_THREAD_INFO(init_task) };
  50
  51/*
  52 * Initial task structure.
  53 *
  54 * All other task structs will be allocated on slabs in fork.c
  55 */
  56struct task_struct init_task = INIT_TASK(init_task);
  57
  58EXPORT_SYMBOL(init_task);
  59
  60/*
  61 * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  62 * there would ever be a halt sequence (for power save when idle) with
  63 * some largish delay when halting or resuming *and* a driver that can't
  64 * afford that delay.  The hlt_counter would then be checked before
  65 * executing the halt sequence, and the driver marks the unhaltable
  66 * region by enable_hlt/disable_hlt.
  67 */
  68
  69int cris_hlt_counter=0;
  70
  71void disable_hlt(void)
  72{
  73        cris_hlt_counter++;
  74}
  75
  76EXPORT_SYMBOL(disable_hlt);
  77
  78void enable_hlt(void)
  79{
  80        cris_hlt_counter--;
  81}
  82
  83EXPORT_SYMBOL(enable_hlt);
  84 
  85/*
  86 * The following aren't currently used.
  87 */
  88void (*pm_idle)(void);
  89
  90extern void default_idle(void);
  91
  92void (*pm_power_off)(void);
  93EXPORT_SYMBOL(pm_power_off);
  94
  95/*
  96 * The idle thread. There's no useful work to be
  97 * done, so just try to conserve power and have a
  98 * low exit latency (ie sit in a loop waiting for
  99 * somebody to say that they'd like to reschedule)
 100 */
 101
 102void cpu_idle (void)
 103{
 104        /* endless idle loop with no priority at all */
 105        while (1) {
 106                while (!need_resched()) {
 107                        void (*idle)(void);
 108                        /*
 109                         * Mark this as an RCU critical section so that
 110                         * synchronize_kernel() in the unload path waits
 111                         * for our completion.
 112                         */
 113                        idle = pm_idle;
 114                        if (!idle)
 115                                idle = default_idle;
 116                        idle();
 117                }
 118                preempt_enable_no_resched();
 119                schedule();
 120                preempt_disable();
 121        }
 122}
 123
 124void hard_reset_now (void);
 125
 126void machine_restart(char *cmd)
 127{
 128        hard_reset_now();
 129}
 130
 131/*
 132 * Similar to machine_power_off, but don't shut off power.  Add code
 133 * here to freeze the system for e.g. post-mortem debug purpose when
 134 * possible.  This halt has nothing to do with the idle halt.
 135 */
 136
 137void machine_halt(void)
 138{
 139}
 140
 141/* If or when software power-off is implemented, add code here.  */
 142
 143void machine_power_off(void)
 144{
 145}
 146
 147/*
 148 * When a process does an "exec", machine state like FPU and debug
 149 * registers need to be reset.  This is a hook function for that.
 150 * Currently we don't have any such state to reset, so this is empty.
 151 */
 152
 153void flush_thread(void)
 154{
 155}
 156
 157/* Fill in the fpu structure for a core dump. */
 158int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 159{
 160        return 0;
 161}
 162
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