Merge branch 'dccp' of git://eden-feed.erg.abdn.ac.uk/dccp_exp
[linux-2.6] / arch / powerpc / platforms / pseries / smp.c
1 /*
2  * SMP support for pSeries machines.
3  *
4  * Dave Engebretsen, Peter Bergner, and
5  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
6  *
7  * Plus various changes from other IBM teams...
8  *
9  *      This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/sched.h>
19 #include <linux/smp.h>
20 #include <linux/interrupt.h>
21 #include <linux/delay.h>
22 #include <linux/init.h>
23 #include <linux/spinlock.h>
24 #include <linux/cache.h>
25 #include <linux/err.h>
26 #include <linux/sysdev.h>
27 #include <linux/cpu.h>
28
29 #include <asm/ptrace.h>
30 #include <asm/atomic.h>
31 #include <asm/irq.h>
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34 #include <asm/io.h>
35 #include <asm/prom.h>
36 #include <asm/smp.h>
37 #include <asm/paca.h>
38 #include <asm/time.h>
39 #include <asm/machdep.h>
40 #include "xics.h"
41 #include <asm/cputable.h>
42 #include <asm/firmware.h>
43 #include <asm/system.h>
44 #include <asm/rtas.h>
45 #include <asm/pSeries_reconfig.h>
46 #include <asm/mpic.h>
47 #include <asm/vdso_datapage.h>
48 #include <asm/cputhreads.h>
49
50 #include "plpar_wrappers.h"
51 #include "pseries.h"
52
53
54 /*
55  * The primary thread of each non-boot processor is recorded here before
56  * smp init.
57  */
58 static cpumask_t of_spin_map;
59
60 extern void generic_secondary_smp_init(unsigned long);
61
62 /**
63  * smp_startup_cpu() - start the given cpu
64  *
65  * At boot time, there is nothing to do for primary threads which were
66  * started from Open Firmware.  For anything else, call RTAS with the
67  * appropriate start location.
68  *
69  * Returns:
70  *      0       - failure
71  *      1       - success
72  */
73 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
74 {
75         int status;
76         unsigned long start_here = __pa((u32)*((unsigned long *)
77                                                generic_secondary_smp_init));
78         unsigned int pcpu;
79         int start_cpu;
80
81         if (cpu_isset(lcpu, of_spin_map))
82                 /* Already started by OF and sitting in spin loop */
83                 return 1;
84
85         pcpu = get_hard_smp_processor_id(lcpu);
86
87         /* Fixup atomic count: it exited inside IRQ handler. */
88         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
89
90         /* 
91          * If the RTAS start-cpu token does not exist then presume the
92          * cpu is already spinning.
93          */
94         start_cpu = rtas_token("start-cpu");
95         if (start_cpu == RTAS_UNKNOWN_SERVICE)
96                 return 1;
97
98         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
99         if (status != 0) {
100                 printk(KERN_ERR "start-cpu failed: %i\n", status);
101                 return 0;
102         }
103
104         return 1;
105 }
106
107 #ifdef CONFIG_XICS
108 static inline void smp_xics_do_message(int cpu, int msg)
109 {
110         set_bit(msg, &xics_ipi_message[cpu].value);
111         mb();
112         xics_cause_IPI(cpu);
113 }
114
115 static void smp_xics_message_pass(int target, int msg)
116 {
117         unsigned int i;
118
119         if (target < NR_CPUS) {
120                 smp_xics_do_message(target, msg);
121         } else {
122                 for_each_online_cpu(i) {
123                         if (target == MSG_ALL_BUT_SELF
124                             && i == smp_processor_id())
125                                 continue;
126                         smp_xics_do_message(i, msg);
127                 }
128         }
129 }
130
131 static int __init smp_xics_probe(void)
132 {
133         xics_request_IPIs();
134
135         return cpus_weight(cpu_possible_map);
136 }
137
138 static void __devinit smp_xics_setup_cpu(int cpu)
139 {
140         if (cpu != boot_cpuid)
141                 xics_setup_cpu();
142
143         if (firmware_has_feature(FW_FEATURE_SPLPAR))
144                 vpa_init(cpu);
145
146         cpu_clear(cpu, of_spin_map);
147
148 }
149 #endif /* CONFIG_XICS */
150
151 static DEFINE_SPINLOCK(timebase_lock);
152 static unsigned long timebase = 0;
153
154 static void __devinit pSeries_give_timebase(void)
155 {
156         spin_lock(&timebase_lock);
157         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
158         timebase = get_tb();
159         spin_unlock(&timebase_lock);
160
161         while (timebase)
162                 barrier();
163         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
164 }
165
166 static void __devinit pSeries_take_timebase(void)
167 {
168         while (!timebase)
169                 barrier();
170         spin_lock(&timebase_lock);
171         set_tb(timebase >> 32, timebase & 0xffffffff);
172         timebase = 0;
173         spin_unlock(&timebase_lock);
174 }
175
176 static void __devinit smp_pSeries_kick_cpu(int nr)
177 {
178         BUG_ON(nr < 0 || nr >= NR_CPUS);
179
180         if (!smp_startup_cpu(nr))
181                 return;
182
183         /*
184          * The processor is currently spinning, waiting for the
185          * cpu_start field to become non-zero After we set cpu_start,
186          * the processor will continue on to secondary_start
187          */
188         paca[nr].cpu_start = 1;
189 }
190
191 static int smp_pSeries_cpu_bootable(unsigned int nr)
192 {
193         /* Special case - we inhibit secondary thread startup
194          * during boot if the user requests it.  Odd-numbered
195          * cpus are assumed to be secondary threads.
196          */
197         if (system_state < SYSTEM_RUNNING &&
198             cpu_has_feature(CPU_FTR_SMT) &&
199             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
200                 return 0;
201
202         return 1;
203 }
204 #ifdef CONFIG_MPIC
205 static struct smp_ops_t pSeries_mpic_smp_ops = {
206         .message_pass   = smp_mpic_message_pass,
207         .probe          = smp_mpic_probe,
208         .kick_cpu       = smp_pSeries_kick_cpu,
209         .setup_cpu      = smp_mpic_setup_cpu,
210 };
211 #endif
212 #ifdef CONFIG_XICS
213 static struct smp_ops_t pSeries_xics_smp_ops = {
214         .message_pass   = smp_xics_message_pass,
215         .probe          = smp_xics_probe,
216         .kick_cpu       = smp_pSeries_kick_cpu,
217         .setup_cpu      = smp_xics_setup_cpu,
218         .cpu_bootable   = smp_pSeries_cpu_bootable,
219 };
220 #endif
221
222 /* This is called very early */
223 static void __init smp_init_pseries(void)
224 {
225         int i;
226
227         pr_debug(" -> smp_init_pSeries()\n");
228
229         /* Mark threads which are still spinning in hold loops. */
230         if (cpu_has_feature(CPU_FTR_SMT)) {
231                 for_each_present_cpu(i) { 
232                         if (i % 2 == 0)
233                                 /*
234                                  * Even-numbered logical cpus correspond to
235                                  * primary threads.
236                                  */
237                                 cpu_set(i, of_spin_map);
238                 }
239         } else {
240                 of_spin_map = cpu_present_map;
241         }
242
243         cpu_clear(boot_cpuid, of_spin_map);
244
245         /* Non-lpar has additional take/give timebase */
246         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
247                 smp_ops->give_timebase = pSeries_give_timebase;
248                 smp_ops->take_timebase = pSeries_take_timebase;
249         }
250
251         pr_debug(" <- smp_init_pSeries()\n");
252 }
253
254 #ifdef CONFIG_MPIC
255 void __init smp_init_pseries_mpic(void)
256 {
257         smp_ops = &pSeries_mpic_smp_ops;
258
259         smp_init_pseries();
260 }
261 #endif
262
263 void __init smp_init_pseries_xics(void)
264 {
265         smp_ops = &pSeries_xics_smp_ops;
266
267         smp_init_pseries();
268 }