[PATCH] pivot_root: add comment
[linux-2.6] / include / asm-frv / system.h
1 /* system.h: FR-V CPU control definitions
2  *
3  * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11
12 #ifndef _ASM_SYSTEM_H
13 #define _ASM_SYSTEM_H
14
15 #include <linux/config.h> /* get configuration macros */
16 #include <linux/linkage.h>
17 #include <asm/atomic.h>
18
19 struct thread_struct;
20
21 #define prepare_to_switch()    do { } while(0)
22
23 /*
24  * switch_to(prev, next) should switch from task `prev' to `next'
25  * `prev' will never be the same as `next'.
26  * The `mb' is to tell GCC not to cache `current' across this call.
27  */
28 extern asmlinkage
29 struct task_struct *__switch_to(struct thread_struct *prev_thread,
30                                 struct thread_struct *next_thread,
31                                 struct task_struct *prev);
32
33 #define switch_to(prev, next, last)                                     \
34 do {                                                                    \
35         (prev)->thread.sched_lr =                                       \
36                 (unsigned long) __builtin_return_address(0);            \
37         (last) = __switch_to(&(prev)->thread, &(next)->thread, (prev)); \
38         mb();                                                           \
39 } while(0)
40
41 /*
42  * interrupt flag manipulation
43  */
44 #define local_irq_disable()                             \
45 do {                                                    \
46         unsigned long psr;                              \
47         asm volatile("  movsg   psr,%0          \n"     \
48                      "  andi    %0,%2,%0        \n"     \
49                      "  ori     %0,%1,%0        \n"     \
50                      "  movgs   %0,psr          \n"     \
51                      : "=r"(psr)                        \
52                      : "i" (PSR_PIL_14), "i" (~PSR_PIL) \
53                      : "memory");                       \
54 } while(0)
55
56 #define local_irq_enable()                              \
57 do {                                                    \
58         unsigned long psr;                              \
59         asm volatile("  movsg   psr,%0          \n"     \
60                      "  andi    %0,%1,%0        \n"     \
61                      "  movgs   %0,psr          \n"     \
62                      : "=r"(psr)                        \
63                      : "i" (~PSR_PIL)                   \
64                      : "memory");                       \
65 } while(0)
66
67 #define local_save_flags(flags)                 \
68 do {                                            \
69         typecheck(unsigned long, flags);        \
70         asm("movsg psr,%0"                      \
71             : "=r"(flags)                       \
72             :                                   \
73             : "memory");                        \
74 } while(0)
75
76 #define local_irq_save(flags)                           \
77 do {                                                    \
78         unsigned long npsr;                             \
79         typecheck(unsigned long, flags);                \
80         asm volatile("  movsg   psr,%0          \n"     \
81                      "  andi    %0,%3,%1        \n"     \
82                      "  ori     %1,%2,%1        \n"     \
83                      "  movgs   %1,psr          \n"     \
84                      : "=r"(flags), "=r"(npsr)          \
85                      : "i" (PSR_PIL_14), "i" (~PSR_PIL) \
86                      : "memory");                       \
87 } while(0)
88
89 #define local_irq_restore(flags)                        \
90 do {                                                    \
91         typecheck(unsigned long, flags);                \
92         asm volatile("  movgs   %0,psr          \n"     \
93                      :                                  \
94                      : "r" (flags)                      \
95                      : "memory");                       \
96 } while(0)
97
98 #define irqs_disabled() \
99         ((__get_PSR() & PSR_PIL) >= PSR_PIL_14)
100
101 /*
102  * Force strict CPU ordering.
103  */
104 #define nop()                   asm volatile ("nop"::)
105 #define mb()                    asm volatile ("membar" : : :"memory")
106 #define rmb()                   asm volatile ("membar" : : :"memory")
107 #define wmb()                   asm volatile ("membar" : : :"memory")
108 #define set_mb(var, value)      do { var = value; mb(); } while (0)
109 #define set_wmb(var, value)     do { var = value; wmb(); } while (0)
110
111 #define smp_mb()                mb()
112 #define smp_rmb()               rmb()
113 #define smp_wmb()               wmb()
114
115 #define read_barrier_depends()          do {} while(0)
116 #define smp_read_barrier_depends()      read_barrier_depends()
117
118 #define HARD_RESET_NOW()                        \
119 do {                                            \
120         cli();                                  \
121 } while(1)
122
123 extern void die_if_kernel(const char *, ...) __attribute__((format(printf, 1, 2)));
124 extern void free_initmem(void);
125
126 #define arch_align_stack(x) (x)
127
128 #endif /* _ASM_SYSTEM_H */