1/*
2 *  Port on Texas Instruments TMS320C6x architecture
3 *
4 *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
5 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
6 *
7 *  This program is free software; you can redistribute it and/or modify
8 *  it under the terms of the GNU General Public License version 2 as
9 *  published by the Free Software Foundation.
10 *
11 */
12#include <linux/module.h>
13#include <linux/unistd.h>
14#include <linux/ptrace.h>
15#include <linux/init_task.h>
16#include <linux/tick.h>
17#include <linux/mqueue.h>
18#include <linux/syscalls.h>
19#include <linux/reboot.h>
20
21#include <asm/syscalls.h>
22
23/* hooks for board specific support */
24void	(*c6x_restart)(void);
25void	(*c6x_halt)(void);
26
27extern asmlinkage void ret_from_fork(void);
28extern asmlinkage void ret_from_kernel_thread(void);
29
30/*
31 * power off function, if any
32 */
33void (*pm_power_off)(void);
34EXPORT_SYMBOL(pm_power_off);
35
36void arch_cpu_idle(void)
37{
38	unsigned long tmp;
39
40	/*
41	 * Put local_irq_enable and idle in same execute packet
42	 * to make them atomic and avoid race to idle with
43	 * interrupts enabled.
44	 */
45	asm volatile ("   mvc .s2 CSR,%0\n"
46		      "   or  .d2 1,%0,%0\n"
47		      "   mvc .s2 %0,CSR\n"
48		      "|| idle\n"
49		      : "=b"(tmp));
50}
51
52static void halt_loop(void)
53{
54	printk(KERN_EMERG "System Halted, OK to turn off power\n");
55	local_irq_disable();
56	while (1)
57		asm volatile("idle\n");
58}
59
60void machine_restart(char *__unused)
61{
62	if (c6x_restart)
63		c6x_restart();
64	halt_loop();
65}
66
67void machine_halt(void)
68{
69	if (c6x_halt)
70		c6x_halt();
71	halt_loop();
72}
73
74void machine_power_off(void)
75{
76	if (pm_power_off)
77		pm_power_off();
78	halt_loop();
79}
80
81void flush_thread(void)
82{
83}
84
85void exit_thread(void)
86{
87}
88
89/*
90 * Do necessary setup to start up a newly executed thread.
91 */
92void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
93{
94	/*
95	 * The binfmt loader will setup a "full" stack, but the C6X
96	 * operates an "empty" stack. So we adjust the usp so that
97	 * argc doesn't get destroyed if an interrupt is taken before
98	 * it is read from the stack.
99	 *
100	 * NB: Library startup code needs to match this.
101	 */
102	usp -= 8;
103
104	regs->pc  = pc;
105	regs->sp  = usp;
106	regs->tsr |= 0x40; /* set user mode */
107	current->thread.usp = usp;
108}
109
110/*
111 * Copy a new thread context in its stack.
112 */
113int copy_thread(unsigned long clone_flags, unsigned long usp,
114		unsigned long ustk_size,
115		struct task_struct *p)
116{
117	struct pt_regs *childregs;
118
119	childregs = task_pt_regs(p);
120
121	if (unlikely(p->flags & PF_KTHREAD)) {
122		/* case of  __kernel_thread: we return to supervisor space */
123		memset(childregs, 0, sizeof(struct pt_regs));
124		childregs->sp = (unsigned long)(childregs + 1);
125		p->thread.pc = (unsigned long) ret_from_kernel_thread;
126		childregs->a0 = usp;		/* function */
127		childregs->a1 = ustk_size;	/* argument */
128	} else {
129		/* Otherwise use the given stack */
130		*childregs = *current_pt_regs();
131		if (usp)
132			childregs->sp = usp;
133		p->thread.pc = (unsigned long) ret_from_fork;
134	}
135
136	/* Set usp/ksp */
137	p->thread.usp = childregs->sp;
138	thread_saved_ksp(p) = (unsigned long)childregs - 8;
139	p->thread.wchan	= p->thread.pc;
140#ifdef __DSBT__
141	{
142		unsigned long dp;
143
144		asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
145
146		thread_saved_dp(p) = dp;
147		if (usp == -1)
148			childregs->dp = dp;
149	}
150#endif
151	return 0;
152}
153
154unsigned long get_wchan(struct task_struct *p)
155{
156	return p->thread.wchan;
157}
158