arch/avr32/include/asm/switch_to.h

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #ifndef __ASM_AVR32_SWITCH_TO_H
   9 #define __ASM_AVR32_SWITCH_TO_H
  10
  11 /*
  12  * Help PathFinder and other Nexus-compliant debuggers keep track of
  13  * the current PID by emitting an Ownership Trace Message each time we
  14  * switch task.
  15  */
  16 #ifdef CONFIG_OWNERSHIP_TRACE
  17 #include <asm/ocd.h>
  18 #define ocd_switch(prev, next)                          \
  19         do {                                            \
  20                 ocd_write(PID, prev->pid);              \
  21                 ocd_write(PID, next->pid);              \
  22         } while(0)
  23 #else
  24 #define ocd_switch(prev, next)
  25 #endif
  26
  27 /*
  28  * switch_to(prev, next, last) should switch from task `prev' to task
  29  * `next'. `prev' will never be the same as `next'.
  30  *
  31  * We just delegate everything to the __switch_to assembly function,
  32  * which is implemented in arch/avr32/kernel/switch_to.S
  33  *
  34  * mb() tells GCC not to cache `current' across this call.
  35  */
  36 struct cpu_context;
  37 struct task_struct;
  38 extern struct task_struct *__switch_to(struct task_struct *,
  39                                        struct cpu_context *,
  40                                        struct cpu_context *);
  41 #define switch_to(prev, next, last)                                     \
  42         do {                                                            \
  43                 ocd_switch(prev, next);                                 \
  44                 last = __switch_to(prev, &prev->thread.cpu_context + 1, \
  45                                    &next->thread.cpu_context);          \
  46         } while (0)
  47
  48
  49 #endif /* __ASM_AVR32_SWITCH_TO_H */