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
  31void (*pm_power_off)(void);
  32EXPORT_SYMBOL(pm_power_off);
  33
  34/* If or when software machine-restart is implemented, add code here. */
  35void machine_restart(char *command) {}
  36
  37/* If or when software machine-halt is implemented, add code here. */
  38void machine_halt(void) {}
  39
  40/* If or when software machine-power-off is implemented, add code here. */
  41void machine_power_off(void) {}
  42
  43/*
  44 * The idle thread. There's no useful work to be
  45 * done, so just try to conserve power and have a
  46 * low exit latency (ie sit in a loop waiting for
  47 * somebody to say that they'd like to reschedule)
  48 */
  49void __noreturn cpu_idle(void)
  50{
  51        /* endless idle loop with no priority at all */
  52        while (1) {
  53                while (!need_resched())
  54                        barrier();
  55
  56                preempt_enable_no_resched();
  57                schedule();
  58                preempt_disable();
  59        }
  60}
  61
  62void ret_from_fork(void);
  63
  64void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
  65{
  66        unsigned long status;
  67
  68        /* New thread loses kernel privileges. */
  69        status = regs->cp0_psr & ~(KU_MASK);
  70        status |= KU_USER;
  71        regs->cp0_psr = status;
  72        regs->cp0_epc = pc;
  73        regs->regs[0] = sp;
  74}
  75
  76void exit_thread(void) {}
  77
  78/*
  79 * When a process does an "exec", machine state like FPU and debug
  80 * registers need to be reset.  This is a hook function for that.
  81 * Currently we don't have any such state to reset, so this is empty.
  82 */
  83void flush_thread(void) {}
  84
  85/*
  86 * set up the kernel stack and exception frames for a new process
  87 */
  88int copy_thread(unsigned long clone_flags, unsigned long usp,
  89                unsigned long unused,
  90                struct task_struct *p, struct pt_regs *regs)
  91{
  92        struct thread_info *ti = task_thread_info(p);
  93        struct pt_regs *childregs = task_pt_regs(p);
  94
  95        p->set_child_tid = NULL;
  96        p->clear_child_tid = NULL;
  97
  98        *childregs = *regs;
  99        childregs->regs[7] = 0;         /* Clear error flag */
 100        childregs->regs[4] = 0;         /* Child gets zero as return value */
 101        regs->regs[4] = p->pid;
 102
 103        if (childregs->cp0_psr & 0x8) { /* test kernel fork or user fork */
 104                childregs->regs[0] = usp;               /* user fork */
 105        } else {
 106                childregs->regs[28] = (unsigned long) ti; /* kernel fork */
 107                childregs->regs[0] = (unsigned long) childregs;
 108        }
 109
 110        p->thread.reg0 = (unsigned long) childregs;
 111        p->thread.reg3 = (unsigned long) ret_from_fork;
 112        p->thread.cp0_psr = 0;
 113
 114        return 0;
 115}
 116
 117/* Fill in the fpu structure for a core dump. */
 118int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 119{
 120        return 1;
 121}
 122
 123static void __noreturn
 124kernel_thread_helper(void *unused0, int (*fn)(void *),
 125                 void *arg, void *unused1)
 126{
 127        do_exit(fn(arg));
 128}
 129
 130/*
 131 * Create a kernel thread.
 132 */
 133long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 134{
 135        struct pt_regs regs;
 136
 137        memset(&regs, 0, sizeof(regs));
 138
 139        regs.regs[6] = (unsigned long) arg;
 140        regs.regs[5] = (unsigned long) fn;
 141        regs.cp0_epc = (unsigned long) kernel_thread_helper;
 142        regs.cp0_psr = (regs.cp0_psr & ~(0x1|0x4|0x8)) | \
 143                        ((regs.cp0_psr & 0x3) << 2);
 144
 145        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, \
 146                        0, &regs, 0, NULL, NULL);
 147}
 148
 149unsigned long thread_saved_pc(struct task_struct *tsk)
 150{
 151        return task_pt_regs(tsk)->cp0_epc;
 152}
 153
 154unsigned long get_wchan(struct task_struct *task)
 155{
 156        if (!task || task == current || task->state == TASK_RUNNING)
 157                return 0;
 158
 159        if (!task_stack_page(task))
 160                return 0;
 161
 162        return task_pt_regs(task)->cp0_epc;
 163}
 164
 165unsigned long arch_align_stack(unsigned long sp)
 166{
 167        return sp;
 168}
 169