LXR linux/arch/score/kernel/process.c

   1/*
   2 * arch/score/kernel/process.c
   3 *
   4 * Score Processor version.
   5 *
   6 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   7 *  Chen Liqin <liqin.chen@sunplusct.com>
   8 *  Lennox Wu <lennox.wu@sunplusct.com>
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License as published by
  12 * the Free Software Foundation; either version 2 of the License, or
  13 * (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, see the file COPYING, or write
  22 * to the Free Software Foundation, Inc.,
  23 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24 */
  25
  26#include <linux/module.h>
  27#include <linux/reboot.h>
  28#include <linux/elfcore.h>
  29#include <linux/pm.h>
  30#include <linux/rcupdate.h>
  31
  32void (*pm_power_off)(void);
  33EXPORT_SYMBOL(pm_power_off);
  34
  35/* If or when software machine-restart is implemented, add code here. */
  36void machine_restart(char *command) {}
  37
  38/* If or when software machine-halt is implemented, add code here. */
  39void machine_halt(void) {}
  40
  41/* If or when software machine-power-off is implemented, add code here. */
  42void machine_power_off(void) {}
  43
  44/*
  45 * The idle thread. There's no useful work to be
  46 * done, so just try to conserve power and have a
  47 * low exit latency (ie sit in a loop waiting for
  48 * somebody to say that they'd like to reschedule)
  49 */
  50void __noreturn cpu_idle(void)
  51{
  52        /* endless idle loop with no priority at all */
  53        while (1) {
  54                rcu_idle_enter();
  55                while (!need_resched())
  56                        barrier();
  57                rcu_idle_exit();
  58                schedule_preempt_disabled();
  59        }
  60}
  61
  62void ret_from_fork(void);
  63void ret_from_kernel_thread(void);
  64
  65void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
  66{
  67        unsigned long status;
  68
  69        /* New thread loses kernel privileges. */
  70        status = regs->cp0_psr & ~(KU_MASK);
  71        status |= KU_USER;
  72        regs->cp0_psr = status;
  73        regs->cp0_epc = pc;
  74        regs->regs[0] = sp;
  75}
  76
  77void exit_thread(void) {}
  78
  79/*
  80 * When a process does an "exec", machine state like FPU and debug
  81 * registers need to be reset.  This is a hook function for that.
  82 * Currently we don't have any such state to reset, so this is empty.
  83 */
  84void flush_thread(void) {}
  85
  86/*
  87 * set up the kernel stack and exception frames for a new process
  88 */
  89int copy_thread(unsigned long clone_flags, unsigned long usp,
  90                unsigned long arg, struct task_struct *p)
  91{
  92        struct thread_info *ti = task_thread_info(p);
  93        struct pt_regs *childregs = task_pt_regs(p);
  94        struct pt_regs *regs = current_pt_regs();
  95
  96        p->thread.reg0 = (unsigned long) childregs;
  97        if (unlikely(p->flags & PF_KTHREAD)) {
  98                memset(childregs, 0, sizeof(struct pt_regs));
  99                p->thread->reg12 = usp;
 100                p->thread->reg13 = arg;
 101                p->thread.reg3 = (unsigned long) ret_from_kernel_thread;
 102        } else {
 103                *childregs = *current_pt_regs();
 104                childregs->regs[7] = 0;         /* Clear error flag */
 105                childregs->regs[4] = 0;         /* Child gets zero as return value */
 106                if (usp)
 107                        childregs->regs[0] = usp;       /* user fork */
 108                p->thread.reg3 = (unsigned long) ret_from_fork;
 109        }
 110
 111        p->thread.cp0_psr = 0;
 112
 113        return 0;
 114}
 115
 116/* Fill in the fpu structure for a core dump. */
 117int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 118{
 119        return 1;
 120}
 121
 122unsigned long thread_saved_pc(struct task_struct *tsk)
 123{
 124        return task_pt_regs(tsk)->cp0_epc;
 125}
 126
 127unsigned long get_wchan(struct task_struct *task)
 128{
 129        if (!task || task == current || task->state == TASK_RUNNING)
 130                return 0;
 131
 132        if (!task_stack_page(task))
 133                return 0;
 134
 135        return task_pt_regs(task)->cp0_epc;
 136}
 137
 138unsigned long arch_align_stack(unsigned long sp)
 139{
 140        return sp;
 141}
 142