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 <linux/module.h>
20 #include <linux/spinlock.h>
21 #include <linux/init_task.h>
22 #include <linux/sched.h>
23 #include <linux/fs.h>
24 #include <linux/user.h>
25 #include <linux/elfcore.h>
26 #include <linux/mqueue.h>
27 #include <linux/reboot.h>
28 #include <linux/rcupdate.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
disable_hlt(void)71 void disable_hlt(void)
72 {
73 cris_hlt_counter++;
74 }
75
76 EXPORT_SYMBOL(disable_hlt);
77
enable_hlt(void)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
cpu_idle(void)102 void cpu_idle (void)
103 {
104 /* endless idle loop with no priority at all */
105 while (1) {
106 rcu_idle_enter();
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 rcu_idle_exit();
120 schedule_preempt_disabled();
121 }
122 }
123
124 void hard_reset_now (void);
125
machine_restart(char * cmd)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
machine_halt(void)137 void machine_halt(void)
138 {
139 }
140
141 /* If or when software power-off is implemented, add code here. */
142
machine_power_off(void)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
flush_thread(void)153 void flush_thread(void)
154 {
155 }
156
157 /* Fill in the fpu structure for a core dump. */
dump_fpu(struct pt_regs * regs,elf_fpregset_t * fpu)158 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
159 {
160 return 0;
161 }
162