1 /*
2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
3  *
4  *   This program is free software; you can redistribute it and/or
5  *   modify it under the terms of the GNU General Public License
6  *   as published by the Free Software Foundation, version 2.
7  *
8  *   This program is distributed in the hope that it will be useful, but
9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11  *   NON INFRINGEMENT.  See the GNU General Public License for
12  *   more details.
13  */
14 
15 #ifndef _ASM_TILE_SWITCH_TO_H
16 #define _ASM_TILE_SWITCH_TO_H
17 
18 #include <arch/sim_def.h>
19 
20 /*
21  * switch_to(n) should switch tasks to task nr n, first
22  * checking that n isn't the current task, in which case it does nothing.
23  * The number of callee-saved registers saved on the kernel stack
24  * is defined here for use in copy_thread() and must agree with __switch_to().
25  */
26 #define CALLEE_SAVED_FIRST_REG 30
27 #define CALLEE_SAVED_REGS_COUNT 24   /* r30 to r52, plus an empty to align */
28 
29 #ifndef __ASSEMBLY__
30 
31 struct task_struct;
32 
33 /*
34  * Pause the DMA engine and static network before task switching.
35  */
36 #define prepare_arch_switch(next) _prepare_arch_switch(next)
37 void _prepare_arch_switch(struct task_struct *next);
38 
39 struct task_struct;
40 #define switch_to(prev, next, last) ((last) = _switch_to((prev), (next)))
41 extern struct task_struct *_switch_to(struct task_struct *prev,
42 				      struct task_struct *next);
43 
44 /* Helper function for _switch_to(). */
45 extern struct task_struct *__switch_to(struct task_struct *prev,
46 				       struct task_struct *next,
47 				       unsigned long new_system_save_k_0);
48 
49 /* Address that switched-away from tasks are at. */
50 extern unsigned long get_switch_to_pc(void);
51 
52 /*
53  * Kernel threads can check to see if they need to migrate their
54  * stack whenever they return from a context switch; for user
55  * threads, we defer until they are returning to user-space.
56  */
57 #define finish_arch_switch(prev) do {                                     \
58 	if (unlikely((prev)->state == TASK_DEAD))                         \
59 		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
60 			((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
61 	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
62 		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
63 	if (current->mm == NULL && !kstack_hash &&                        \
64 	    current_thread_info()->homecache_cpu != smp_processor_id())   \
65 		homecache_migrate_kthread();                              \
66 } while (0)
67 
68 /* Support function for forking a new task. */
69 void ret_from_fork(void);
70 
71 /* Called from ret_from_fork() when a new process starts up. */
72 struct task_struct *sim_notify_fork(struct task_struct *prev);
73 
74 #endif /* !__ASSEMBLY__ */
75 
76 #endif /* _ASM_TILE_SWITCH_TO_H */
77