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
31 void (*pm_power_off)(void);
32 EXPORT_SYMBOL(pm_power_off);
33
34 /* If or when software machine-restart is implemented, add code here. */
machine_restart(char * command)35 void machine_restart(char *command) {}
36
37 /* If or when software machine-halt is implemented, add code here. */
machine_halt(void)38 void machine_halt(void) {}
39
40 /* If or when software machine-power-off is implemented, add code here. */
machine_power_off(void)41 void 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 */
cpu_idle(void)49 void __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
62 void ret_from_fork(void);
63
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long sp)64 void 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
exit_thread(void)76 void 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 */
flush_thread(void)83 void flush_thread(void) {}
84
85 /*
86 * set up the kernel stack and exception frames for a new process
87 */
copy_thread(unsigned long clone_flags,unsigned long usp,unsigned long unused,struct task_struct * p,struct pt_regs * regs)88 int 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. */
dump_fpu(struct pt_regs * regs,elf_fpregset_t * r)118 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
119 {
120 return 1;
121 }
122
123 static void __noreturn
kernel_thread_helper(void * unused0,int (* fn)(void *),void * arg,void * unused1)124 kernel_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 */
kernel_thread(int (* fn)(void *),void * arg,unsigned long flags)133 long 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
thread_saved_pc(struct task_struct * tsk)149 unsigned long thread_saved_pc(struct task_struct *tsk)
150 {
151 return task_pt_regs(tsk)->cp0_epc;
152 }
153
get_wchan(struct task_struct * task)154 unsigned 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
arch_align_stack(unsigned long sp)165 unsigned long arch_align_stack(unsigned long sp)
166 {
167 return sp;
168 }
169