arch/arm/kernel/reboot.c

   1 /*
   2  *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
   3  *  Original Copyright (C) 1995  Linus Torvalds
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9 #include <linux/cpu.h>
  10 #include <linux/delay.h>
  11 #include <linux/reboot.h>
  12
  13 #include <asm/cacheflush.h>
  14 #include <asm/idmap.h>
  15 #include <asm/virt.h>
  16
  17 #include "reboot.h"
  18
  19 typedef void (*phys_reset_t)(unsigned long, bool);
  20
  21 /*
  22  * Function pointers to optional machine specific functions
  23  */
  24 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
  25 void (*pm_power_off)(void);
  26 EXPORT_SYMBOL(pm_power_off);
  27
  28 /*
  29  * A temporary stack to use for CPU reset. This is static so that we
  30  * don't clobber it with the identity mapping. When running with this
  31  * stack, any references to the current task *will not work* so you
  32  * should really do as little as possible before jumping to your reset
  33  * code.
  34  */
  35 static u64 soft_restart_stack[16];
  36
  37 static void __soft_restart(void *addr)
  38 {
  39         phys_reset_t phys_reset;
  40
  41         /* Take out a flat memory mapping. */
  42         setup_mm_for_reboot();
  43
  44         /* Clean and invalidate caches */
  45         flush_cache_all();
  46
  47         /* Turn off caching */
  48         cpu_proc_fin();
  49
  50         /* Push out any further dirty data, and ensure cache is empty */
  51         flush_cache_all();
  52
  53         /* Switch to the identity mapping. */
  54         phys_reset = (phys_reset_t)virt_to_idmap(cpu_reset);
  55
  56         /* original stub should be restored by kvm */
  57         phys_reset((unsigned long)addr, is_hyp_mode_available());
  58
  59         /* Should never get here. */
  60         BUG();
  61 }
  62
  63 void _soft_restart(unsigned long addr, bool disable_l2)
  64 {
  65         u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
  66
  67         /* Disable interrupts first */
  68         raw_local_irq_disable();
  69         local_fiq_disable();
  70
  71         /* Disable the L2 if we're the last man standing. */
  72         if (disable_l2)
  73                 outer_disable();
  74
  75         /* Change to the new stack and continue with the reset. */
  76         call_with_stack(__soft_restart, (void *)addr, (void *)stack);
  77
  78         /* Should never get here. */
  79         BUG();
  80 }
  81
  82 void soft_restart(unsigned long addr)
  83 {
  84         _soft_restart(addr, num_online_cpus() == 1);
  85 }
  86
  87 /*
  88  * Called by kexec, immediately prior to machine_kexec().
  89  *
  90  * This must completely disable all secondary CPUs; simply causing those CPUs
  91  * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
  92  * kexec'd kernel to use any and all RAM as it sees fit, without having to
  93  * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
  94  * functionality embodied in disable_nonboot_cpus() to achieve this.
  95  */
  96 void machine_shutdown(void)
  97 {
  98         disable_nonboot_cpus();
  99 }
 100
 101 /*
 102  * Halting simply requires that the secondary CPUs stop performing any
 103  * activity (executing tasks, handling interrupts). smp_send_stop()
 104  * achieves this.
 105  */
 106 void machine_halt(void)
 107 {
 108         machine_power_off();
 109 }
 110
 111 /*
 112  * Power-off simply requires that the secondary CPUs stop performing any
 113  * activity (executing tasks, handling interrupts). smp_send_stop()
 114  * achieves this. When the system power is turned off, it will take all CPUs
 115  * with it.
 116  */
 117 void machine_power_off(void)
 118 {
 119         local_irq_disable();
 120         smp_send_stop();
 121
 122         if (pm_power_off)
 123                 pm_power_off();
 124 }
 125
 126 /*
 127  * Restart requires that the secondary CPUs stop performing any activity
 128  * while the primary CPU resets the system. Systems with a single CPU can
 129  * use soft_restart() as their machine descriptor's .restart hook, since that
 130  * will cause the only available CPU to reset. Systems with multiple CPUs must
 131  * provide a HW restart implementation, to ensure that all CPUs reset at once.
 132  * This is required so that any code running after reset on the primary CPU
 133  * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 134  * executing pre-reset code, and using RAM that the primary CPU's code wishes
 135  * to use. Implementing such co-ordination would be essentially impossible.
 136  */
 137 void machine_restart(char *cmd)
 138 {
 139         local_irq_disable();
 140         smp_send_stop();
 141
 142         if (arm_pm_restart)
 143                 arm_pm_restart(reboot_mode, cmd);
 144         else
 145                 do_kernel_restart(cmd);
 146
 147         /* Give a grace period for failure to restart of 1s */
 148         mdelay(1000);
 149
 150         /* Whoops - the platform was unable to reboot. Tell the user! */
 151         printk("Reboot failed -- System halted\n");
 152         while (1);
 153 }