xref: /openbmc/linux/arch/sh/kernel/smp.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * arch/sh/kernel/smp.c
3  *
4  * SMP support for the SuperH processors.
5  *
6  * Copyright (C) 2002, 2003 Paul Mundt
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License as published by the
10  * Free Software Foundation; either version 2 of the License, or (at your
11  * option) any later version.
12  */
13 #include <linux/config.h>
14 #include <linux/cache.h>
15 #include <linux/cpumask.h>
16 #include <linux/delay.h>
17 #include <linux/init.h>
18 #include <linux/interrupt.h>
19 #include <linux/spinlock.h>
20 #include <linux/threads.h>
21 #include <linux/module.h>
22 #include <linux/time.h>
23 #include <linux/timex.h>
24 #include <linux/sched.h>
25 #include <linux/module.h>
26 
27 #include <asm/atomic.h>
28 #include <asm/processor.h>
29 #include <asm/system.h>
30 #include <asm/mmu_context.h>
31 #include <asm/smp.h>
32 
33 /*
34  * This was written with the Sega Saturn (SMP SH-2 7604) in mind,
35  * but is designed to be usable regardless if there's an MMU
36  * present or not.
37  */
38 struct sh_cpuinfo cpu_data[NR_CPUS];
39 
40 extern void per_cpu_trap_init(void);
41 
42 cpumask_t cpu_possible_map;
43 EXPORT_SYMBOL(cpu_possible_map);
44 
45 cpumask_t cpu_online_map;
46 static atomic_t cpus_booted = ATOMIC_INIT(0);
47 
48 /* These are defined by the board-specific code. */
49 
50 /*
51  * Cause the function described by call_data to be executed on the passed
52  * cpu.  When the function has finished, increment the finished field of
53  * call_data.
54  */
55 void __smp_send_ipi(unsigned int cpu, unsigned int action);
56 
57 /*
58  * Find the number of available processors
59  */
60 unsigned int __smp_probe_cpus(void);
61 
62 /*
63  * Start a particular processor
64  */
65 void __smp_slave_init(unsigned int cpu);
66 
67 /*
68  * Run specified function on a particular processor.
69  */
70 void __smp_call_function(unsigned int cpu);
71 
72 static inline void __init smp_store_cpu_info(unsigned int cpu)
73 {
74 	cpu_data[cpu].loops_per_jiffy = loops_per_jiffy;
75 }
76 
77 void __init smp_prepare_cpus(unsigned int max_cpus)
78 {
79 	unsigned int cpu = smp_processor_id();
80 	int i;
81 
82 	atomic_set(&cpus_booted, 1);
83 	smp_store_cpu_info(cpu);
84 
85 	for (i = 0; i < __smp_probe_cpus(); i++)
86 		cpu_set(i, cpu_possible_map);
87 }
88 
89 void __devinit smp_prepare_boot_cpu(void)
90 {
91 	unsigned int cpu = smp_processor_id();
92 
93 	cpu_set(cpu, cpu_online_map);
94 	cpu_set(cpu, cpu_possible_map);
95 }
96 
97 int __cpu_up(unsigned int cpu)
98 {
99 	struct task_struct *tsk;
100 
101 	tsk = fork_idle(cpu);
102 
103 	if (IS_ERR(tsk))
104 		panic("Failed forking idle task for cpu %d\n", cpu);
105 
106 	tsk->thread_info->cpu = cpu;
107 
108 	cpu_set(cpu, cpu_online_map);
109 
110 	return 0;
111 }
112 
113 int start_secondary(void *unused)
114 {
115 	unsigned int cpu = smp_processor_id();
116 
117 	atomic_inc(&init_mm.mm_count);
118 	current->active_mm = &init_mm;
119 
120 	smp_store_cpu_info(cpu);
121 
122 	__smp_slave_init(cpu);
123 	per_cpu_trap_init();
124 
125 	atomic_inc(&cpus_booted);
126 
127 	cpu_idle();
128 	return 0;
129 }
130 
131 void __init smp_cpus_done(unsigned int max_cpus)
132 {
133 	smp_mb();
134 }
135 
136 void smp_send_reschedule(int cpu)
137 {
138 	__smp_send_ipi(cpu, SMP_MSG_RESCHEDULE);
139 }
140 
141 static void stop_this_cpu(void *unused)
142 {
143 	cpu_clear(smp_processor_id(), cpu_online_map);
144 	local_irq_disable();
145 
146 	for (;;)
147 		cpu_relax();
148 }
149 
150 void smp_send_stop(void)
151 {
152 	smp_call_function(stop_this_cpu, 0, 1, 0);
153 }
154 
155 
156 struct smp_fn_call_struct smp_fn_call = {
157 	.lock		= SPIN_LOCK_UNLOCKED,
158 	.finished	= ATOMIC_INIT(0),
159 };
160 
161 /*
162  * The caller of this wants the passed function to run on every cpu.  If wait
163  * is set, wait until all cpus have finished the function before returning.
164  * The lock is here to protect the call structure.
165  * You must not call this function with disabled interrupts or from a
166  * hardware interrupt handler or from a bottom half handler.
167  */
168 int smp_call_function(void (*func)(void *info), void *info, int retry, int wait)
169 {
170 	unsigned int nr_cpus = atomic_read(&cpus_booted);
171 	int i;
172 
173 	if (nr_cpus < 2)
174 		return 0;
175 
176 	/* Can deadlock when called with interrupts disabled */
177 	WARN_ON(irqs_disabled());
178 
179 	spin_lock(&smp_fn_call.lock);
180 
181 	atomic_set(&smp_fn_call.finished, 0);
182 	smp_fn_call.fn = func;
183 	smp_fn_call.data = info;
184 
185 	for (i = 0; i < nr_cpus; i++)
186 		if (i != smp_processor_id())
187 			__smp_call_function(i);
188 
189 	if (wait)
190 		while (atomic_read(&smp_fn_call.finished) != (nr_cpus - 1));
191 
192 	spin_unlock(&smp_fn_call.lock);
193 
194 	return 0;
195 }
196 
197 /* Not really SMP stuff ... */
198 int setup_profiling_timer(unsigned int multiplier)
199 {
200 	return 0;
201 }
202 
203