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 files_struct init_files = INIT_FILES;
  42 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  43 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  44 struct mm_struct init_mm = INIT_MM(init_mm);
  45
  46 EXPORT_SYMBOL(init_mm);
  47
  48 /*
  49  * Initial thread structure.
  50  *
  51  * We need to make sure that this is 8192-byte aligned due to the
  52  * way process stacks are handled. This is done by having a special
  53  * "init_task" linker map entry..
  54  */
  55 union thread_union init_thread_union
  56         __attribute__((__section__(".data.init_task"))) =
  57                 { INIT_THREAD_INFO(init_task) };
  58
  59 /*
  60  * Initial task structure.
  61  *
  62  * All other task structs will be allocated on slabs in fork.c
  63  */
  64 struct task_struct init_task = INIT_TASK(init_task);
  65
  66 EXPORT_SYMBOL(init_task);
  67
  68 /*
  69  * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  70  * there would ever be a halt sequence (for power save when idle) with
  71  * some largish delay when halting or resuming *and* a driver that can't
  72  * afford that delay.  The hlt_counter would then be checked before
  73  * executing the halt sequence, and the driver marks the unhaltable
  74  * region by enable_hlt/disable_hlt.
  75  */
  76
  77 int cris_hlt_counter=0;
  78
  79 void disable_hlt(void)
  80 {
  81         cris_hlt_counter++;
  82 }
  83
  84 EXPORT_SYMBOL(disable_hlt);
  85
  86 void enable_hlt(void)
  87 {
  88         cris_hlt_counter--;
  89 }
  90
  91 EXPORT_SYMBOL(enable_hlt);
  92
  93 /*
  94  * The following aren't currently used.
  95  */
  96 void (*pm_idle)(void);
  97
  98 extern void default_idle(void);
  99
 100 void (*pm_power_off)(void);
 101 EXPORT_SYMBOL(pm_power_off);
 102
 103 /*
 104  * The idle thread. There's no useful work to be
 105  * done, so just try to conserve power and have a
 106  * low exit latency (ie sit in a loop waiting for
 107  * somebody to say that they'd like to reschedule)
 108  */
 109
 110 void cpu_idle (void)
 111 {
 112         /* endless idle loop with no priority at all */
 113         while (1) {
 114                 while (!need_resched()) {
 115                         void (*idle)(void);
 116                         /*
 117                          * Mark this as an RCU critical section so that
 118                          * synchronize_kernel() in the unload path waits
 119                          * for our completion.
 120                          */
 121                         idle = pm_idle;
 122                         if (!idle)
 123                                 idle = default_idle;
 124                         idle();
 125                 }
 126                 preempt_enable_no_resched();
 127                 schedule();
 128                 preempt_disable();
 129         }
 130 }
 131
 132 void hard_reset_now (void);
 133
 134 void machine_restart(char *cmd)
 135 {
 136         hard_reset_now();
 137 }
 138
 139 /*
 140  * Similar to machine_power_off, but don't shut off power.  Add code
 141  * here to freeze the system for e.g. post-mortem debug purpose when
 142  * possible.  This halt has nothing to do with the idle halt.
 143  */
 144
 145 void machine_halt(void)
 146 {
 147 }
 148
 149 /* If or when software power-off is implemented, add code here.  */
 150
 151 void machine_power_off(void)
 152 {
 153 }
 154
 155 /*
 156  * When a process does an "exec", machine state like FPU and debug
 157  * registers need to be reset.  This is a hook function for that.
 158  * Currently we don't have any such state to reset, so this is empty.
 159  */
 160
 161 void flush_thread(void)
 162 {
 163 }
 164
 165 /* Fill in the fpu structure for a core dump. */
 166 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 167 {
 168         return 0;
 169 }