kernel/cpu.c: create a CPU_STARTING cpu_chain notifier
[linux-2.6.git] / arch / um / kernel / smp.c
1 /*
2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Licensed under the GPL
4  */
5
6 #include "linux/percpu.h"
7 #include "asm/pgalloc.h"
8 #include "asm/tlb.h"
9
10 /* For some reason, mmu_gathers are referenced when CONFIG_SMP is off. */
11 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
12
13 #ifdef CONFIG_SMP
14
15 #include "linux/sched.h"
16 #include "linux/module.h"
17 #include "linux/threads.h"
18 #include "linux/interrupt.h"
19 #include "linux/err.h"
20 #include "linux/hardirq.h"
21 #include "asm/smp.h"
22 #include "asm/processor.h"
23 #include "asm/spinlock.h"
24 #include "kern.h"
25 #include "irq_user.h"
26 #include "os.h"
27
28 /* CPU online map, set by smp_boot_cpus */
29 cpumask_t cpu_online_map = CPU_MASK_NONE;
30 cpumask_t cpu_possible_map = CPU_MASK_NONE;
31
32 EXPORT_SYMBOL(cpu_online_map);
33 EXPORT_SYMBOL(cpu_possible_map);
34
35 /* Per CPU bogomips and other parameters
36  * The only piece used here is the ipi pipe, which is set before SMP is
37  * started and never changed.
38  */
39 struct cpuinfo_um cpu_data[NR_CPUS];
40
41 /* A statistic, can be a little off */
42 int num_reschedules_sent = 0;
43
44 /* Not changed after boot */
45 struct task_struct *idle_threads[NR_CPUS];
46
47 void smp_send_reschedule(int cpu)
48 {
49         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
50         num_reschedules_sent++;
51 }
52
53 void smp_send_stop(void)
54 {
55         int i;
56
57         printk(KERN_INFO "Stopping all CPUs...");
58         for (i = 0; i < num_online_cpus(); i++) {
59                 if (i == current_thread->cpu)
60                         continue;
61                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
62         }
63         printk(KERN_CONT "done\n");
64 }
65
66 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
67 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
68
69 static int idle_proc(void *cpup)
70 {
71         int cpu = (int) cpup, err;
72
73         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
74         if (err < 0)
75                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
76
77         os_set_fd_async(cpu_data[cpu].ipi_pipe[0]);
78
79         wmb();
80         if (cpu_test_and_set(cpu, cpu_callin_map)) {
81                 printk(KERN_ERR "huh, CPU#%d already present??\n", cpu);
82                 BUG();
83         }
84
85         while (!cpu_isset(cpu, smp_commenced_mask))
86                 cpu_relax();
87
88         notify_cpu_starting(cpu);
89         cpu_set(cpu, cpu_online_map);
90         default_idle();
91         return 0;
92 }
93
94 static struct task_struct *idle_thread(int cpu)
95 {
96         struct task_struct *new_task;
97
98         current->thread.request.u.thread.proc = idle_proc;
99         current->thread.request.u.thread.arg = (void *) cpu;
100         new_task = fork_idle(cpu);
101         if (IS_ERR(new_task))
102                 panic("copy_process failed in idle_thread, error = %ld",
103                       PTR_ERR(new_task));
104
105         cpu_tasks[cpu] = ((struct cpu_task)
106                           { .pid =      new_task->thread.mode.tt.extern_pid,
107                             .task =     new_task } );
108         idle_threads[cpu] = new_task;
109         panic("skas mode doesn't support SMP");
110         return new_task;
111 }
112
113 void smp_prepare_cpus(unsigned int maxcpus)
114 {
115         struct task_struct *idle;
116         unsigned long waittime;
117         int err, cpu, me = smp_processor_id();
118         int i;
119
120         for (i = 0; i < ncpus; ++i)
121                 cpu_set(i, cpu_possible_map);
122
123         cpu_clear(me, cpu_online_map);
124         cpu_set(me, cpu_online_map);
125         cpu_set(me, cpu_callin_map);
126
127         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
128         if (err < 0)
129                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
130
131         os_set_fd_async(cpu_data[me].ipi_pipe[0]);
132
133         for (cpu = 1; cpu < ncpus; cpu++) {
134                 printk(KERN_INFO "Booting processor %d...\n", cpu);
135
136                 idle = idle_thread(cpu);
137
138                 init_idle(idle, cpu);
139
140                 waittime = 200000000;
141                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
142                         cpu_relax();
143
144                 printk(KERN_INFO "%s\n",
145                        cpu_isset(cpu, cpu_calling_map) ? "done" : "failed");
146         }
147 }
148
149 void smp_prepare_boot_cpu(void)
150 {
151         cpu_set(smp_processor_id(), cpu_online_map);
152 }
153
154 int __cpu_up(unsigned int cpu)
155 {
156         cpu_set(cpu, smp_commenced_mask);
157         while (!cpu_isset(cpu, cpu_online_map))
158                 mb();
159         return 0;
160 }
161
162 int setup_profiling_timer(unsigned int multiplier)
163 {
164         printk(KERN_INFO "setup_profiling_timer\n");
165         return 0;
166 }
167
168 void smp_call_function_slave(int cpu);
169
170 void IPI_handler(int cpu)
171 {
172         unsigned char c;
173         int fd;
174
175         fd = cpu_data[cpu].ipi_pipe[0];
176         while (os_read_file(fd, &c, 1) == 1) {
177                 switch (c) {
178                 case 'C':
179                         smp_call_function_slave(cpu);
180                         break;
181
182                 case 'R':
183                         set_tsk_need_resched(current);
184                         break;
185
186                 case 'S':
187                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
188                         while (1)
189                                 pause();
190                         break;
191
192                 default:
193                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
194                                cpu, c);
195                         break;
196                 }
197         }
198 }
199
200 int hard_smp_processor_id(void)
201 {
202         return pid_to_processor_id(os_getpid());
203 }
204
205 static DEFINE_SPINLOCK(call_lock);
206 static atomic_t scf_started;
207 static atomic_t scf_finished;
208 static void (*func)(void *info);
209 static void *info;
210
211 void smp_call_function_slave(int cpu)
212 {
213         atomic_inc(&scf_started);
214         (*func)(info);
215         atomic_inc(&scf_finished);
216 }
217
218 int smp_call_function(void (*_func)(void *info), void *_info, int wait)
219 {
220         int cpus = num_online_cpus() - 1;
221         int i;
222
223         if (!cpus)
224                 return 0;
225
226         /* Can deadlock when called with interrupts disabled */
227         WARN_ON(irqs_disabled());
228
229         spin_lock_bh(&call_lock);
230         atomic_set(&scf_started, 0);
231         atomic_set(&scf_finished, 0);
232         func = _func;
233         info = _info;
234
235         for_each_online_cpu(i)
236                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
237
238         while (atomic_read(&scf_started) != cpus)
239                 barrier();
240
241         if (wait)
242                 while (atomic_read(&scf_finished) != cpus)
243                         barrier();
244
245         spin_unlock_bh(&call_lock);
246         return 0;
247 }
248
249 #endif