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
