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