/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/

#ifndef _ASM_TILE_SWITCH_TO_H
#define _ASM_TILE_SWITCH_TO_H

#include <arch/sim_def.h>

/*
* switch_to(n) should switch tasks to task nr n, first
* checking that n isn't the current task, in which case it does nothing.
* The number of callee-saved registers saved on the kernel stack
* is defined here for use in copy_thread() and must agree with __switch_to().
*/
#define CALLEE_SAVED_FIRST_REG 30
#define CALLEE_SAVED_REGS_COUNT 24 /* r30 to r52, plus an empty to align */

#ifndef __ASSEMBLY__

struct task_struct;

/*
* Pause the DMA engine and static network before task switching.
*/
#define prepare_arch_switch(next) _prepare_arch_switch(next)
void _prepare_arch_switch(struct task_struct *next);

struct task_struct;
#define switch_to(prev, next, last) ((last) = _switch_to((prev), (next)))
extern struct task_struct *_switch_to(struct task_struct *prev,
struct task_struct *next);

/* Helper function for _switch_to(). */
extern struct task_struct *__switch_to(struct task_struct *prev,
struct task_struct *next,
unsigned long new_system_save_k_0);

/* Address that switched-away from tasks are at. */
extern unsigned long get_switch_to_pc(void);

/*
* Kernel threads can check to see if they need to migrate their
* stack whenever they return from a context switch; for user
* threads, we defer until they are returning to user-space.
*/
#define finish_arch_switch(prev) do { \
if (unlikely((prev)->state == TASK_DEAD)) \
__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT | \
((prev)->pid << _SIM_CONTROL_OPERATOR_BITS)); \
__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH | \
(current->pid << _SIM_CONTROL_OPERATOR_BITS)); \
if (current->mm == NULL && !kstack_hash && \
current_thread_info()->homecache_cpu != smp_processor_id()) \
homecache_migrate_kthread(); \
} while (0)

/* Support function for forking a new task. */
void ret_from_fork(void);

/* Support function for forking a new kernel thread. */
void ret_from_kernel_thread(void *fn, void *arg);

/* Called from ret_from_xxx() when a new process starts up. */
struct task_struct *sim_notify_fork(struct task_struct *prev);

#endif /* !__ASSEMBLY__ */

#endif /* _ASM_TILE_SWITCH_TO_H */