1/*
2 *  linux/arch/cris/kernel/process.c
3 *
4 *  Copyright (C) 1995  Linus Torvalds
5 *  Copyright (C) 2000-2002  Axis Communications AB
6 *
7 *  Authors:   Bjorn Wesen (bjornw@axis.com)
8 *             Mikael Starvik (starvik@axis.com)
9 *
10 * This file handles the architecture-dependent parts of process handling..
11 */
12
13#include <linux/sched.h>
14#include <linux/slab.h>
15#include <linux/err.h>
16#include <linux/fs.h>
17#include <arch/svinto.h>
18#include <linux/init.h>
19#include <arch/system.h>
20#include <linux/ptrace.h>
21
22#ifdef CONFIG_ETRAX_GPIO
23void etrax_gpio_wake_up_check(void); /* drivers/gpio.c */
24#endif
25
26/*
27 * We use this if we don't have any better
28 * idle routine..
29 */
30void default_idle(void)
31{
32#ifdef CONFIG_ETRAX_GPIO
33	etrax_gpio_wake_up_check();
34#endif
35	local_irq_enable();
36}
37
38/*
39 * Free current thread data structures etc..
40 */
41
42void exit_thread(void)
43{
44	/* Nothing needs to be done.  */
45}
46
47/* if the watchdog is enabled, we can simply disable interrupts and go
48 * into an eternal loop, and the watchdog will reset the CPU after 0.1s
49 * if on the other hand the watchdog wasn't enabled, we just enable it and wait
50 */
51
52void hard_reset_now (void)
53{
54	/*
55	 * Don't declare this variable elsewhere.  We don't want any other
56	 * code to know about it than the watchdog handler in entry.S and
57	 * this code, implementing hard reset through the watchdog.
58	 */
59#if defined(CONFIG_ETRAX_WATCHDOG)
60	extern int cause_of_death;
61#endif
62
63	printk("*** HARD RESET ***\n");
64	local_irq_disable();
65
66#if defined(CONFIG_ETRAX_WATCHDOG)
67	cause_of_death = 0xbedead;
68#else
69	/* Since we dont plan to keep on resetting the watchdog,
70	   the key can be arbitrary hence three */
71	*R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, 3) |
72		IO_STATE(R_WATCHDOG, enable, start);
73#endif
74
75	while(1) /* waiting for RETRIBUTION! */ ;
76}
77
78/*
79 * Return saved PC of a blocked thread.
80 */
81unsigned long thread_saved_pc(struct task_struct *t)
82{
83	return task_pt_regs(t)->irp;
84}
85
86/* setup the child's kernel stack with a pt_regs and switch_stack on it.
87 * it will be un-nested during _resume and _ret_from_sys_call when the
88 * new thread is scheduled.
89 *
90 * also setup the thread switching structure which is used to keep
91 * thread-specific data during _resumes.
92 *
93 */
94asmlinkage void ret_from_fork(void);
95asmlinkage void ret_from_kernel_thread(void);
96
97int copy_thread(unsigned long clone_flags, unsigned long usp,
98		unsigned long arg, struct task_struct *p)
99{
100	struct pt_regs *childregs = task_pt_regs(p);
101	struct switch_stack *swstack = ((struct switch_stack *)childregs) - 1;
102
103	/* put the pt_regs structure at the end of the new kernel stack page and fix it up
104	 * remember that the task_struct doubles as the kernel stack for the task
105	 */
106
107	if (unlikely(p->flags & PF_KTHREAD)) {
108		memset(swstack, 0,
109			sizeof(struct switch_stack) + sizeof(struct pt_regs));
110		swstack->r1 = usp;
111		swstack->r2 = arg;
112		childregs->dccr = 1 << I_DCCR_BITNR;
113		swstack->return_ip = (unsigned long) ret_from_kernel_thread;
114		p->thread.ksp = (unsigned long) swstack;
115		p->thread.usp = 0;
116		return 0;
117	}
118	*childregs = *current_pt_regs();  /* struct copy of pt_regs */
119
120        childregs->r10 = 0;  /* child returns 0 after a fork/clone */
121
122	/* put the switch stack right below the pt_regs */
123
124	swstack->r9 = 0; /* parameter to ret_from_sys_call, 0 == dont restart the syscall */
125
126	/* we want to return into ret_from_sys_call after the _resume */
127
128	swstack->return_ip = (unsigned long) ret_from_fork; /* Will call ret_from_sys_call */
129
130	/* fix the user-mode stackpointer */
131
132	p->thread.usp = usp ?: rdusp();
133
134	/* and the kernel-mode one */
135
136	p->thread.ksp = (unsigned long) swstack;
137
138#ifdef DEBUG
139	printk("copy_thread: new regs at 0x%p, as shown below:\n", childregs);
140	show_registers(childregs);
141#endif
142
143	return 0;
144}
145
146unsigned long get_wchan(struct task_struct *p)
147{
148#if 0
149	/* YURGH. TODO. */
150
151        unsigned long ebp, esp, eip;
152        unsigned long stack_page;
153        int count = 0;
154        if (!p || p == current || p->state == TASK_RUNNING)
155                return 0;
156        stack_page = (unsigned long)p;
157        esp = p->thread.esp;
158        if (!stack_page || esp < stack_page || esp > 8188+stack_page)
159                return 0;
160        /* include/asm-i386/system.h:switch_to() pushes ebp last. */
161        ebp = *(unsigned long *) esp;
162        do {
163                if (ebp < stack_page || ebp > 8184+stack_page)
164                        return 0;
165                eip = *(unsigned long *) (ebp+4);
166		if (!in_sched_functions(eip))
167			return eip;
168                ebp = *(unsigned long *) ebp;
169        } while (count++ < 16);
170#endif
171        return 0;
172}
173#undef last_sched
174#undef first_sched
175
176void show_regs(struct pt_regs * regs)
177{
178	unsigned long usp = rdusp();
179
180	show_regs_print_info(KERN_DEFAULT);
181
182	printk("IRP: %08lx SRP: %08lx DCCR: %08lx USP: %08lx MOF: %08lx\n",
183	       regs->irp, regs->srp, regs->dccr, usp, regs->mof );
184	printk(" r0: %08lx  r1: %08lx   r2: %08lx  r3: %08lx\n",
185	       regs->r0, regs->r1, regs->r2, regs->r3);
186	printk(" r4: %08lx  r5: %08lx   r6: %08lx  r7: %08lx\n",
187	       regs->r4, regs->r5, regs->r6, regs->r7);
188	printk(" r8: %08lx  r9: %08lx  r10: %08lx r11: %08lx\n",
189	       regs->r8, regs->r9, regs->r10, regs->r11);
190	printk("r12: %08lx r13: %08lx oR10: %08lx\n",
191	       regs->r12, regs->r13, regs->orig_r10);
192}
193
194