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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 */
22 void	(*c6x_restart)(void);
23 void	(*c6x_halt)(void);
24 
25 extern asmlinkage void ret_from_fork(void);
26 extern asmlinkage void ret_from_kernel_thread(void);
27 
28 /*
29  * power off function, if any
30  */
31 void (*pm_power_off)(void);
32 EXPORT_SYMBOL(pm_power_off);
33 
arch_cpu_idle(void)34 void 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 
halt_loop(void)50 static 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 
machine_restart(char * __unused)58 void machine_restart(char *__unused)
59 {
60 	if (c6x_restart)
61 		c6x_restart();
62 	halt_loop();
63 }
64 
machine_halt(void)65 void machine_halt(void)
66 {
67 	if (c6x_halt)
68 		c6x_halt();
69 	halt_loop();
70 }
71 
machine_power_off(void)72 void machine_power_off(void)
73 {
74 	if (pm_power_off)
75 		pm_power_off();
76 	halt_loop();
77 }
78 
flush_thread(void)79 void flush_thread(void)
80 {
81 }
82 
83 /*
84  * Do necessary setup to start up a newly executed thread.
85  */
start_thread(struct pt_regs * regs,unsigned int pc,unsigned long usp)86 void 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  */
copy_thread(unsigned long clone_flags,unsigned long usp,unsigned long ustk_size,struct task_struct * p,unsigned long tls)107 int copy_thread(unsigned long clone_flags, unsigned long usp,
108 		unsigned long ustk_size, struct task_struct *p,
109 		unsigned long tls)
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 
get_wchan(struct task_struct * p)148 unsigned long get_wchan(struct task_struct *p)
149 {
150 	return p->thread.wchan;
151 }
152