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
 85/*
 86 * Do necessary setup to start up a newly executed thread.
 87 */
 88void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
 89{
 90	/*
 91	 * The binfmt loader will setup a "full" stack, but the C6X
 92	 * operates an "empty" stack. So we adjust the usp so that
 93	 * argc doesn't get destroyed if an interrupt is taken before
 94	 * it is read from the stack.
 95	 *
 96	 * NB: Library startup code needs to match this.
 97	 */
 98	usp -= 8;
 99
100	regs->pc  = pc;
101	regs->sp  = usp;
102	regs->tsr |= 0x40; /* set user mode */
103	current->thread.usp = usp;
104}
105
106/*
107 * Copy a new thread context in its stack.
108 */
109int copy_thread(unsigned long clone_flags, unsigned long usp,
110		unsigned long ustk_size,
111		struct task_struct *p)
112{
113	struct pt_regs *childregs;
114
115	childregs = task_pt_regs(p);
116
117	if (unlikely(p->flags & PF_KTHREAD)) {
118		/* case of  __kernel_thread: we return to supervisor space */
119		memset(childregs, 0, sizeof(struct pt_regs));
120		childregs->sp = (unsigned long)(childregs + 1);
121		p->thread.pc = (unsigned long) ret_from_kernel_thread;
122		childregs->a0 = usp;		/* function */
123		childregs->a1 = ustk_size;	/* argument */
124	} else {
125		/* Otherwise use the given stack */
126		*childregs = *current_pt_regs();
127		if (usp)
128			childregs->sp = usp;
129		p->thread.pc = (unsigned long) ret_from_fork;
130	}
131
132	/* Set usp/ksp */
133	p->thread.usp = childregs->sp;
134	thread_saved_ksp(p) = (unsigned long)childregs - 8;
135	p->thread.wchan	= p->thread.pc;
136#ifdef __DSBT__
137	{
138		unsigned long dp;
139
140		asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
141
142		thread_saved_dp(p) = dp;
143		if (usp == -1)
144			childregs->dp = dp;
145	}
146#endif
147	return 0;
148}
149
150unsigned long get_wchan(struct task_struct *p)
151{
152	return p->thread.wchan;
153}