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/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
  49         __attribute__((__section__(".data.init_task"))) =
  50                 { INIT_THREAD_INFO(init_task) };
  51
  52 /*
  53  * Initial task structure.
  54  *
  55  * All other task structs will be allocated on slabs in fork.c
  56  */
  57 struct task_struct init_task = INIT_TASK(init_task);
  58
  59 EXPORT_SYMBOL(init_task);
  60
  61 /*
  62  * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  63  * there would ever be a halt sequence (for power save when idle) with
  64  * some largish delay when halting or resuming *and* a driver that can't
  65  * afford that delay.  The hlt_counter would then be checked before
  66  * executing the halt sequence, and the driver marks the unhaltable
  67  * region by enable_hlt/disable_hlt.
  68  */
  69
  70 int cris_hlt_counter=0;
  71
  72 void disable_hlt(void)
  73 {
  74         cris_hlt_counter++;
  75 }
  76
  77 EXPORT_SYMBOL(disable_hlt);
  78
  79 void enable_hlt(void)
  80 {
  81         cris_hlt_counter--;
  82 }
  83
  84 EXPORT_SYMBOL(enable_hlt);
  85
  86 /*
  87  * The following aren't currently used.
  88  */
  89 void (*pm_idle)(void);
  90
  91 extern void default_idle(void);
  92
  93 void (*pm_power_off)(void);
  94 EXPORT_SYMBOL(pm_power_off);
  95
  96 /*
  97  * The idle thread. There's no useful work to be
  98  * done, so just try to conserve power and have a
  99  * low exit latency (ie sit in a loop waiting for
 100  * somebody to say that they'd like to reschedule)
 101  */
 102
 103 void cpu_idle (void)
 104 {
 105         /* endless idle loop with no priority at all */
 106         while (1) {
 107                 while (!need_resched()) {
 108                         void (*idle)(void);
 109                         /*
 110                          * Mark this as an RCU critical section so that
 111                          * synchronize_kernel() in the unload path waits
 112                          * for our completion.
 113                          */
 114                         idle = pm_idle;
 115                         if (!idle)
 116                                 idle = default_idle;
 117                         idle();
 118                 }
 119                 preempt_enable_no_resched();
 120                 schedule();
 121                 preempt_disable();
 122         }
 123 }
 124
 125 void hard_reset_now (void);
 126
 127 void machine_restart(char *cmd)
 128 {
 129         hard_reset_now();
 130 }
 131
 132 /*
 133  * Similar to machine_power_off, but don't shut off power.  Add code
 134  * here to freeze the system for e.g. post-mortem debug purpose when
 135  * possible.  This halt has nothing to do with the idle halt.
 136  */
 137
 138 void machine_halt(void)
 139 {
 140 }
 141
 142 /* If or when software power-off is implemented, add code here.  */
 143
 144 void machine_power_off(void)
 145 {
 146 }
 147
 148 /*
 149  * When a process does an "exec", machine state like FPU and debug
 150  * registers need to be reset.  This is a hook function for that.
 151  * Currently we don't have any such state to reset, so this is empty.
 152  */
 153
 154 void flush_thread(void)
 155 {
 156 }
 157
 158 /* Fill in the fpu structure for a core dump. */
 159 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 160 {
 161         return 0;
 162 }