GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / kernel / reset.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2001, 06 by Ralf Baechle (ralf@linux-mips.org)
7  * Copyright (C) 2001 MIPS Technologies, Inc.
8  */
9 #include <linux/kernel.h>
10 #include <linux/export.h>
11 #include <linux/pm.h>
12 #include <linux/types.h>
13 #include <linux/reboot.h>
14 #include <linux/delay.h>
15
16 #include <asm/compiler.h>
17 #include <asm/idle.h>
18 #include <asm/mipsregs.h>
19 #include <asm/reboot.h>
20
21 /*
22  * Urgs ...  Too many MIPS machines to handle this in a generic way.
23  * So handle all using function pointers to machine specific
24  * functions.
25  */
26 void (*_machine_restart)(char *command);
27 void (*_machine_halt)(void);
28 void (*pm_power_off)(void);
29
30 EXPORT_SYMBOL(pm_power_off);
31
32 static void machine_hang(void)
33 {
34         /*
35          * We're hanging the system so we don't want to be interrupted anymore.
36          * Any interrupt handlers that ran would at best be useless & at worst
37          * go awry because the system isn't in a functional state.
38          */
39         local_irq_disable();
40
41         /*
42          * Mask all interrupts, giving us a better chance of remaining in the
43          * low power wait state.
44          */
45         clear_c0_status(ST0_IM);
46
47         while (true) {
48                 if (cpu_has_mips_r) {
49                         /*
50                          * We know that the wait instruction is supported so
51                          * make use of it directly, leaving interrupts
52                          * disabled.
53                          */
54                         asm volatile(
55                                 ".set   push\n\t"
56                                 ".set   " MIPS_ISA_ARCH_LEVEL "\n\t"
57                                 "wait\n\t"
58                                 ".set   pop");
59                 } else if (cpu_wait) {
60                         /*
61                          * Try the cpu_wait() callback. This isn't ideal since
62                          * it'll re-enable interrupts, but that ought to be
63                          * harmless given that they're all masked.
64                          */
65                         cpu_wait();
66                         local_irq_disable();
67                 } else {
68                         /*
69                          * We're going to burn some power running round the
70                          * loop, but we don't really have a choice. This isn't
71                          * a path we should expect to run for long during
72                          * typical use anyway.
73                          */
74                 }
75
76                 /*
77                  * In most modern MIPS CPUs interrupts will cause the wait
78                  * instruction to graduate even when disabled, and in some
79                  * cases even when masked. In order to prevent a timer
80                  * interrupt from continuously taking us out of the low power
81                  * wait state, we clear any pending timer interrupt here.
82                  */
83                 if (cpu_has_counter)
84                         write_c0_compare(0);
85         }
86 }
87
88 void machine_restart(char *command)
89 {
90         if (_machine_restart)
91                 _machine_restart(command);
92
93 #ifdef CONFIG_SMP
94         preempt_disable();
95         smp_send_stop();
96 #endif
97         do_kernel_restart(command);
98         mdelay(1000);
99         pr_emerg("Reboot failed -- System halted\n");
100         machine_hang();
101 }
102
103 void machine_halt(void)
104 {
105         if (_machine_halt)
106                 _machine_halt();
107
108 #ifdef CONFIG_SMP
109         preempt_disable();
110         smp_send_stop();
111 #endif
112         machine_hang();
113 }
114
115 void machine_power_off(void)
116 {
117         if (pm_power_off)
118                 pm_power_off();
119
120 #ifdef CONFIG_SMP
121         preempt_disable();
122         smp_send_stop();
123 #endif
124         machine_hang();
125 }