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 #include <asm/system_misc.h> 14 15 #include "reboot.h" 16 17 typedef void (*phys_reset_t)(unsigned long, bool); 18 19 /* 20 * Function pointers to optional machine specific functions 21 */ 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 smp_shutdown_nonboot_cpus() to achieve this. 92 */ 93 void machine_shutdown(void) 94 { 95 smp_shutdown_nonboot_cpus(reboot_cpu); 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 do_kernel_power_off(); 121 } 122 123 /* 124 * Restart requires that the secondary CPUs stop performing any activity 125 * while the primary CPU resets the system. Systems with a single CPU can 126 * use soft_restart() as their machine descriptor's .restart hook, since that 127 * will cause the only available CPU to reset. Systems with multiple CPUs must 128 * provide a HW restart implementation, to ensure that all CPUs reset at once. 129 * This is required so that any code running after reset on the primary CPU 130 * doesn't have to co-ordinate with other CPUs to ensure they aren't still 131 * executing pre-reset code, and using RAM that the primary CPU's code wishes 132 * to use. Implementing such co-ordination would be essentially impossible. 133 */ 134 void machine_restart(char *cmd) 135 { 136 local_irq_disable(); 137 smp_send_stop(); 138 139 do_kernel_restart(cmd); 140 141 /* Give a grace period for failure to restart of 1s */ 142 mdelay(1000); 143 144 /* Whoops - the platform was unable to reboot. Tell the user! */ 145 printk("Reboot failed -- System halted\n"); 146 while (1); 147 } 148