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