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