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
  32 void (*pm_power_off)(void);
  33 EXPORT_SYMBOL(pm_power_off);
  34
  35 /* If or when software machine-restart is implemented, add code here. */
  36 void machine_restart(char *command) {}
  37
  38 /* If or when software machine-halt is implemented, add code here. */
  39 void machine_halt(void) {}
  40
  41 /* If or when software machine-power-off is implemented, add code here. */
  42 void 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  */
  50 void __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
  62 void ret_from_fork(void);
  63 void ret_from_kernel_thread(void);
  64
  65 void 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
  77 void 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  */
  84 void flush_thread(void) {}
  85
  86 /*
  87  * set up the kernel stack and exception frames for a new process
  88  */
  89 int copy_thread(unsigned long clone_flags, unsigned long usp,
  90                 unsigned long arg,
  91                 struct task_struct *p, struct pt_regs *regs)
  92 {
  93         struct thread_info *ti = task_thread_info(p);
  94         struct pt_regs *childregs = task_pt_regs(p);
  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. */
 117 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 118 {
 119         return 1;
 120 }
 121
 122 unsigned long thread_saved_pc(struct task_struct *tsk)
 123 {
 124         return task_pt_regs(tsk)->cp0_epc;
 125 }
 126
 127 unsigned 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
 138 unsigned long arch_align_stack(unsigned long sp)
 139 {
 140         return sp;
 141 }