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 <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
  39 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  40 static 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  */
  48 union 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  */
  56 struct task_struct init_task = INIT_TASK(init_task);
  57
  58 EXPORT_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
  69 int cris_hlt_counter=0;
  70
  71 void disable_hlt(void)
  72 {
  73         cris_hlt_counter++;
  74 }
  75
  76 EXPORT_SYMBOL(disable_hlt);
  77
  78 void enable_hlt(void)
  79 {
  80         cris_hlt_counter--;
  81 }
  82
  83 EXPORT_SYMBOL(enable_hlt);
  84
  85 /*
  86  * The following aren't currently used.
  87  */
  88 void (*pm_idle)(void);
  89
  90 extern void default_idle(void);
  91
  92 void (*pm_power_off)(void);
  93 EXPORT_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
 102 void 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
 124 void hard_reset_now (void);
 125
 126 void 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
 137 void machine_halt(void)
 138 {
 139 }
 140
 141 /* If or when software power-off is implemented, add code here.  */
 142
 143 void 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
 153 void flush_thread(void)
 154 {
 155 }
 156
 157 /* Fill in the fpu structure for a core dump. */
 158 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 159 {
 160         return 0;
 161 }