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 <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/fs_struct.h>
  23 #include <linux/init_task.h>
  24 #include <linux/sched.h>
  25 #include <linux/fs.h>
  26 #include <linux/user.h>
  27 #include <linux/elfcore.h>
  28 #include <linux/mqueue.h>
  29 #include <linux/reboot.h>
  30
  31 //#define DEBUG
  32
  33 /*
  34  * Initial task structure. Make this a per-architecture thing,
  35  * because different architectures tend to have different
  36  * alignment requirements and potentially different initial
  37  * setup.
  38  */
  39
  40 static struct fs_struct init_fs = INIT_FS;
  41 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  42 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  43 struct mm_struct init_mm = INIT_MM(init_mm);
  44
  45 EXPORT_SYMBOL(init_mm);
  46
  47 /*
  48  * Initial thread structure.
  49  *
  50  * We need to make sure that this is 8192-byte aligned due to the
  51  * way process stacks are handled. This is done by having a special
  52  * "init_task" linker map entry..
  53  */
  54 union thread_union init_thread_union
  55         __attribute__((__section__(".data.init_task"))) =
  56                 { INIT_THREAD_INFO(init_task) };
  57
  58 /*
  59  * Initial task structure.
  60  *
  61  * All other task structs will be allocated on slabs in fork.c
  62  */
  63 struct task_struct init_task = INIT_TASK(init_task);
  64
  65 EXPORT_SYMBOL(init_task);
  66
  67 /*
  68  * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  69  * there would ever be a halt sequence (for power save when idle) with
  70  * some largish delay when halting or resuming *and* a driver that can't
  71  * afford that delay.  The hlt_counter would then be checked before
  72  * executing the halt sequence, and the driver marks the unhaltable
  73  * region by enable_hlt/disable_hlt.
  74  */
  75
  76 int cris_hlt_counter=0;
  77
  78 void disable_hlt(void)
  79 {
  80         cris_hlt_counter++;
  81 }
  82
  83 EXPORT_SYMBOL(disable_hlt);
  84
  85 void enable_hlt(void)
  86 {
  87         cris_hlt_counter--;
  88 }
  89
  90 EXPORT_SYMBOL(enable_hlt);
  91
  92 /*
  93  * The following aren't currently used.
  94  */
  95 void (*pm_idle)(void);
  96
  97 extern void default_idle(void);
  98
  99 void (*pm_power_off)(void);
 100 EXPORT_SYMBOL(pm_power_off);
 101
 102 /*
 103  * The idle thread. There's no useful work to be
 104  * done, so just try to conserve power and have a
 105  * low exit latency (ie sit in a loop waiting for
 106  * somebody to say that they'd like to reschedule)
 107  */
 108
 109 void cpu_idle (void)
 110 {
 111         /* endless idle loop with no priority at all */
 112         while (1) {
 113                 while (!need_resched()) {
 114                         void (*idle)(void);
 115                         /*
 116                          * Mark this as an RCU critical section so that
 117                          * synchronize_kernel() in the unload path waits
 118                          * for our completion.
 119                          */
 120                         idle = pm_idle;
 121                         if (!idle)
 122                                 idle = default_idle;
 123                         idle();
 124                 }
 125                 preempt_enable_no_resched();
 126                 schedule();
 127                 preempt_disable();
 128         }
 129 }
 130
 131 void hard_reset_now (void);
 132
 133 void machine_restart(char *cmd)
 134 {
 135         hard_reset_now();
 136 }
 137
 138 /*
 139  * Similar to machine_power_off, but don't shut off power.  Add code
 140  * here to freeze the system for e.g. post-mortem debug purpose when
 141  * possible.  This halt has nothing to do with the idle halt.
 142  */
 143
 144 void machine_halt(void)
 145 {
 146 }
 147
 148 /* If or when software power-off is implemented, add code here.  */
 149
 150 void machine_power_off(void)
 151 {
 152 }
 153
 154 /*
 155  * When a process does an "exec", machine state like FPU and debug
 156  * registers need to be reset.  This is a hook function for that.
 157  * Currently we don't have any such state to reset, so this is empty.
 158  */
 159
 160 void flush_thread(void)
 161 {
 162 }
 163
 164 /* Fill in the fpu structure for a core dump. */
 165 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 166 {
 167         return 0;
 168 }