1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
  4 *  Original Copyright (C) 1995  Linus Torvalds
  5 */
  6#include <linux/cpu.h>
  7#include <linux/delay.h>
  8#include <linux/reboot.h>
  9
 10#include <asm/cacheflush.h>
 11#include <asm/idmap.h>
 12#include <asm/virt.h>
 13
 14#include "reboot.h"
 15
 16typedef void (*phys_reset_t)(unsigned long, bool);
 17
 18/*
 19 * Function pointers to optional machine specific functions
 20 */
 21void (*pm_power_off)(void);
 22EXPORT_SYMBOL(pm_power_off);
 23
 24/*
 25 * A temporary stack to use for CPU reset. This is static so that we
 26 * don't clobber it with the identity mapping. When running with this
 27 * stack, any references to the current task *will not work* so you
 28 * should really do as little as possible before jumping to your reset
 29 * code.
 30 */
 31static u64 soft_restart_stack[16];
 32
 33static void __soft_restart(void *addr)
 34{
 35	phys_reset_t phys_reset;
 36
 37	/* Take out a flat memory mapping. */
 38	setup_mm_for_reboot();
 39
 40	/* Clean and invalidate caches */
 41	flush_cache_all();
 42
 43	/* Turn off caching */
 44	cpu_proc_fin();
 45
 46	/* Push out any further dirty data, and ensure cache is empty */
 47	flush_cache_all();
 48
 49	/* Switch to the identity mapping. */
 50	phys_reset = (phys_reset_t)virt_to_idmap(cpu_reset);
 51
 52	/* original stub should be restored by kvm */
 53	phys_reset((unsigned long)addr, is_hyp_mode_available());
 54
 55	/* Should never get here. */
 56	BUG();
 57}
 58
 59void _soft_restart(unsigned long addr, bool disable_l2)
 60{
 61	u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
 62
 63	/* Disable interrupts first */
 64	raw_local_irq_disable();
 65	local_fiq_disable();
 66
 67	/* Disable the L2 if we're the last man standing. */
 68	if (disable_l2)
 69		outer_disable();
 70
 71	/* Change to the new stack and continue with the reset. */
 72	call_with_stack(__soft_restart, (void *)addr, (void *)stack);
 73
 74	/* Should never get here. */
 75	BUG();
 76}
 77
 78void soft_restart(unsigned long addr)
 79{
 80	_soft_restart(addr, num_online_cpus() == 1);
 81}
 82
 83/*
 84 * Called by kexec, immediately prior to machine_kexec().
 85 *
 86 * This must completely disable all secondary CPUs; simply causing those CPUs
 87 * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
 88 * kexec'd kernel to use any and all RAM as it sees fit, without having to
 89 * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
 90 * functionality embodied in smp_shutdown_nonboot_cpus() to achieve this.
 91 */
 92void machine_shutdown(void)
 93{
 94	smp_shutdown_nonboot_cpus(reboot_cpu);
 95}
 96
 97/*
 98 * Halting simply requires that the secondary CPUs stop performing any
 99 * activity (executing tasks, handling interrupts). smp_send_stop()
100 * achieves this.
101 */
102void machine_halt(void)
103{
104	local_irq_disable();
105	smp_send_stop();
106	while (1);
107}
108
109/*
110 * Power-off simply requires that the secondary CPUs stop performing any
111 * activity (executing tasks, handling interrupts). smp_send_stop()
112 * achieves this. When the system power is turned off, it will take all CPUs
113 * with it.
114 */
115void machine_power_off(void)
116{
117	local_irq_disable();
118	smp_send_stop();
119
120	if (pm_power_off)
121		pm_power_off();
122}
123
124/*
125 * Restart requires that the secondary CPUs stop performing any activity
126 * while the primary CPU resets the system. Systems with a single CPU can
127 * use soft_restart() as their machine descriptor's .restart hook, since that
128 * will cause the only available CPU to reset. Systems with multiple CPUs must
129 * provide a HW restart implementation, to ensure that all CPUs reset at once.
130 * This is required so that any code running after reset on the primary CPU
131 * doesn't have to co-ordinate with other CPUs to ensure they aren't still
132 * executing pre-reset code, and using RAM that the primary CPU's code wishes
133 * to use. Implementing such co-ordination would be essentially impossible.
134 */
135void machine_restart(char *cmd)
136{
137	local_irq_disable();
138	smp_send_stop();
139
140	do_kernel_restart(cmd);
141
142	/* Give a grace period for failure to restart of 1s */
143	mdelay(1000);
144
145	/* Whoops - the platform was unable to reboot. Tell the user! */
146	printk("Reboot failed -- System halted\n");
147	while (1);
148}