arch/c6x/kernel/process.c

   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 */
  26 void    (*c6x_restart)(void);
  27 void    (*c6x_halt)(void);
  28
  29 extern asmlinkage void ret_from_fork(void);
  30 extern asmlinkage void ret_from_kernel_thread(void);
  31
  32 /*
  33  * power off function, if any
  34  */
  35 void (*pm_power_off)(void);
  36 EXPORT_SYMBOL(pm_power_off);
  37
  38 void 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
  54 static 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
  62 void machine_restart(char *__unused)
  63 {
  64         if (c6x_restart)
  65                 c6x_restart();
  66         halt_loop();
  67 }
  68
  69 void machine_halt(void)
  70 {
  71         if (c6x_halt)
  72                 c6x_halt();
  73         halt_loop();
  74 }
  75
  76 void machine_power_off(void)
  77 {
  78         if (pm_power_off)
  79                 pm_power_off();
  80         halt_loop();
  81 }
  82
  83 void flush_thread(void)
  84 {
  85 }
  86
  87 /*
  88  * Do necessary setup to start up a newly executed thread.
  89  */
  90 void 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  */
 111 int 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
 152 unsigned long get_wchan(struct task_struct *p)
 153 {
 154         return p->thread.wchan;
 155 }