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
  22 #include <asm/syscalls.h>
  23
  24 /* hooks for board specific support */
  25 void    (*c6x_restart)(void);
  26 void    (*c6x_halt)(void);
  27
  28 extern asmlinkage void ret_from_fork(void);
  29 extern asmlinkage void ret_from_kernel_thread(void);
  30
  31 /*
  32  * power off function, if any
  33  */
  34 void (*pm_power_off)(void);
  35 EXPORT_SYMBOL(pm_power_off);
  36
  37 void arch_cpu_idle(void)
  38 {
  39         unsigned long tmp;
  40
  41         /*
  42          * Put local_irq_enable and idle in same execute packet
  43          * to make them atomic and avoid race to idle with
  44          * interrupts enabled.
  45          */
  46         asm volatile ("   mvc .s2 CSR,%0\n"
  47                       "   or  .d2 1,%0,%0\n"
  48                       "   mvc .s2 %0,CSR\n"
  49                       "|| idle\n"
  50                       : "=b"(tmp));
  51 }
  52
  53 static void halt_loop(void)
  54 {
  55         printk(KERN_EMERG "System Halted, OK to turn off power\n");
  56         local_irq_disable();
  57         while (1)
  58                 asm volatile("idle\n");
  59 }
  60
  61 void machine_restart(char *__unused)
  62 {
  63         if (c6x_restart)
  64                 c6x_restart();
  65         halt_loop();
  66 }
  67
  68 void machine_halt(void)
  69 {
  70         if (c6x_halt)
  71                 c6x_halt();
  72         halt_loop();
  73 }
  74
  75 void machine_power_off(void)
  76 {
  77         if (pm_power_off)
  78                 pm_power_off();
  79         halt_loop();
  80 }
  81
  82 void flush_thread(void)
  83 {
  84 }
  85
  86 /*
  87  * Do necessary setup to start up a newly executed thread.
  88  */
  89 void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
  90 {
  91         /*
  92          * The binfmt loader will setup a "full" stack, but the C6X
  93          * operates an "empty" stack. So we adjust the usp so that
  94          * argc doesn't get destroyed if an interrupt is taken before
  95          * it is read from the stack.
  96          *
  97          * NB: Library startup code needs to match this.
  98          */
  99         usp -= 8;
 100
 101         regs->pc  = pc;
 102         regs->sp  = usp;
 103         regs->tsr |= 0x40; /* set user mode */
 104         current->thread.usp = usp;
 105 }
 106
 107 /*
 108  * Copy a new thread context in its stack.
 109  */
 110 int copy_thread(unsigned long clone_flags, unsigned long usp,
 111                 unsigned long ustk_size,
 112                 struct task_struct *p)
 113 {
 114         struct pt_regs *childregs;
 115
 116         childregs = task_pt_regs(p);
 117
 118         if (unlikely(p->flags & PF_KTHREAD)) {
 119                 /* case of  __kernel_thread: we return to supervisor space */
 120                 memset(childregs, 0, sizeof(struct pt_regs));
 121                 childregs->sp = (unsigned long)(childregs + 1);
 122                 p->thread.pc = (unsigned long) ret_from_kernel_thread;
 123                 childregs->a0 = usp;            /* function */
 124                 childregs->a1 = ustk_size;      /* argument */
 125         } else {
 126                 /* Otherwise use the given stack */
 127                 *childregs = *current_pt_regs();
 128                 if (usp)
 129                         childregs->sp = usp;
 130                 p->thread.pc = (unsigned long) ret_from_fork;
 131         }
 132
 133         /* Set usp/ksp */
 134         p->thread.usp = childregs->sp;
 135         thread_saved_ksp(p) = (unsigned long)childregs - 8;
 136         p->thread.wchan = p->thread.pc;
 137 #ifdef __DSBT__
 138         {
 139                 unsigned long dp;
 140
 141                 asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
 142
 143                 thread_saved_dp(p) = dp;
 144                 if (usp == -1)
 145                         childregs->dp = dp;
 146         }
 147 #endif
 148         return 0;
 149 }
 150
 151 unsigned long get_wchan(struct task_struct *p)
 152 {
 153         return p->thread.wchan;
 154 }