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(®s, 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, ®s, 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