1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  Port on Texas Instruments TMS320C6x architecture
  4 *
  5 *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
  6 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
  7 */
  8#include <linux/module.h>
  9#include <linux/unistd.h>
 10#include <linux/ptrace.h>
 11#include <linux/init_task.h>
 12#include <linux/tick.h>
 13#include <linux/mqueue.h>
 14#include <linux/syscalls.h>
 15#include <linux/reboot.h>
 16#include <linux/sched/task.h>
 17#include <linux/sched/task_stack.h>
 18
 19#include <asm/syscalls.h>
 20
 21/* hooks for board specific support */
 22void	(*c6x_restart)(void);
 23void	(*c6x_halt)(void);
 24
 25extern asmlinkage void ret_from_fork(void);
 26extern asmlinkage void ret_from_kernel_thread(void);
 27
 28/*
 29 * power off function, if any
 30 */
 31void (*pm_power_off)(void);
 32EXPORT_SYMBOL(pm_power_off);
 33
 34void arch_cpu_idle(void)
 35{
 36	unsigned long tmp;
 37
 38	/*
 39	 * Put local_irq_enable and idle in same execute packet
 40	 * to make them atomic and avoid race to idle with
 41	 * interrupts enabled.
 42	 */
 43	asm volatile ("   mvc .s2 CSR,%0\n"
 44		      "   or  .d2 1,%0,%0\n"
 45		      "   mvc .s2 %0,CSR\n"
 46		      "|| idle\n"
 47		      : "=b"(tmp));
 48}
 49
 50static void halt_loop(void)
 51{
 52	printk(KERN_EMERG "System Halted, OK to turn off power\n");
 53	local_irq_disable();
 54	while (1)
 55		asm volatile("idle\n");
 56}
 57
 58void machine_restart(char *__unused)
 59{
 60	if (c6x_restart)
 61		c6x_restart();
 62	halt_loop();
 63}
 64
 65void machine_halt(void)
 66{
 67	if (c6x_halt)
 68		c6x_halt();
 69	halt_loop();
 70}
 71
 72void machine_power_off(void)
 73{
 74	if (pm_power_off)
 75		pm_power_off();
 76	halt_loop();
 77}
 78
 79void flush_thread(void)
 80{
 81}
 82
 83/*
 84 * Do necessary setup to start up a newly executed thread.
 85 */
 86void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
 87{
 88	/*
 89	 * The binfmt loader will setup a "full" stack, but the C6X
 90	 * operates an "empty" stack. So we adjust the usp so that
 91	 * argc doesn't get destroyed if an interrupt is taken before
 92	 * it is read from the stack.
 93	 *
 94	 * NB: Library startup code needs to match this.
 95	 */
 96	usp -= 8;
 97
 98	regs->pc  = pc;
 99	regs->sp  = usp;
100	regs->tsr |= 0x40; /* set user mode */
101	current->thread.usp = usp;
102}
103
104/*
105 * Copy a new thread context in its stack.
106 */
107int copy_thread(unsigned long clone_flags, unsigned long usp,
108		unsigned long ustk_size,
109		struct task_struct *p)
110{
111	struct pt_regs *childregs;
112
113	childregs = task_pt_regs(p);
114
115	if (unlikely(p->flags & PF_KTHREAD)) {
116		/* case of  __kernel_thread: we return to supervisor space */
117		memset(childregs, 0, sizeof(struct pt_regs));
118		childregs->sp = (unsigned long)(childregs + 1);
119		p->thread.pc = (unsigned long) ret_from_kernel_thread;
120		childregs->a0 = usp;		/* function */
121		childregs->a1 = ustk_size;	/* argument */
122	} else {
123		/* Otherwise use the given stack */
124		*childregs = *current_pt_regs();
125		if (usp)
126			childregs->sp = usp;
127		p->thread.pc = (unsigned long) ret_from_fork;
128	}
129
130	/* Set usp/ksp */
131	p->thread.usp = childregs->sp;
132	thread_saved_ksp(p) = (unsigned long)childregs - 8;
133	p->thread.wchan	= p->thread.pc;
134#ifdef __DSBT__
135	{
136		unsigned long dp;
137
138		asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
139
140		thread_saved_dp(p) = dp;
141		if (usp == -1)
142			childregs->dp = dp;
143	}
144#endif
145	return 0;
146}
147
148unsigned long get_wchan(struct task_struct *p)
149{
150	return p->thread.wchan;
151}