Merge commit 'v2.6.28-rc1' into sched/urgent
[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 <asm/cputable.h>
41 #include <asm/firmware.h>
42 #include <asm/system.h>
43 #include <asm/rtas.h>
44 #include <asm/pSeries_reconfig.h>
45 #include <asm/mpic.h>
46 #include <asm/vdso_datapage.h>
47 #include <asm/cputhreads.h>
48
49 #include "plpar_wrappers.h"
50 #include "pseries.h"
51 #include "xics.h"
52
53
54 /*
55  * The Primary thread of each non-boot processor was started from the OF client
56  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
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 void __devinit smp_xics_setup_cpu(int cpu)
109 {
110         if (cpu != boot_cpuid)
111                 xics_setup_cpu();
112
113         if (firmware_has_feature(FW_FEATURE_SPLPAR))
114                 vpa_init(cpu);
115
116         cpu_clear(cpu, of_spin_map);
117
118 }
119 #endif /* CONFIG_XICS */
120
121 static DEFINE_SPINLOCK(timebase_lock);
122 static unsigned long timebase = 0;
123
124 static void __devinit pSeries_give_timebase(void)
125 {
126         spin_lock(&timebase_lock);
127         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
128         timebase = get_tb();
129         spin_unlock(&timebase_lock);
130
131         while (timebase)
132                 barrier();
133         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
134 }
135
136 static void __devinit pSeries_take_timebase(void)
137 {
138         while (!timebase)
139                 barrier();
140         spin_lock(&timebase_lock);
141         set_tb(timebase >> 32, timebase & 0xffffffff);
142         timebase = 0;
143         spin_unlock(&timebase_lock);
144 }
145
146 static void __devinit smp_pSeries_kick_cpu(int nr)
147 {
148         BUG_ON(nr < 0 || nr >= NR_CPUS);
149
150         if (!smp_startup_cpu(nr))
151                 return;
152
153         /*
154          * The processor is currently spinning, waiting for the
155          * cpu_start field to become non-zero After we set cpu_start,
156          * the processor will continue on to secondary_start
157          */
158         paca[nr].cpu_start = 1;
159 }
160
161 static int smp_pSeries_cpu_bootable(unsigned int nr)
162 {
163         /* Special case - we inhibit secondary thread startup
164          * during boot if the user requests it.
165          */
166         if (system_state < SYSTEM_RUNNING &&
167             cpu_has_feature(CPU_FTR_SMT) &&
168             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
169                 return 0;
170
171         return 1;
172 }
173 #ifdef CONFIG_MPIC
174 static struct smp_ops_t pSeries_mpic_smp_ops = {
175         .message_pass   = smp_mpic_message_pass,
176         .probe          = smp_mpic_probe,
177         .kick_cpu       = smp_pSeries_kick_cpu,
178         .setup_cpu      = smp_mpic_setup_cpu,
179 };
180 #endif
181 #ifdef CONFIG_XICS
182 static struct smp_ops_t pSeries_xics_smp_ops = {
183         .message_pass   = smp_xics_message_pass,
184         .probe          = smp_xics_probe,
185         .kick_cpu       = smp_pSeries_kick_cpu,
186         .setup_cpu      = smp_xics_setup_cpu,
187         .cpu_bootable   = smp_pSeries_cpu_bootable,
188 };
189 #endif
190
191 /* This is called very early */
192 static void __init smp_init_pseries(void)
193 {
194         int i;
195
196         pr_debug(" -> smp_init_pSeries()\n");
197
198         /* Mark threads which are still spinning in hold loops. */
199         if (cpu_has_feature(CPU_FTR_SMT)) {
200                 for_each_present_cpu(i) { 
201                         if (cpu_thread_in_core(i) == 0)
202                                 cpu_set(i, of_spin_map);
203                 }
204         } else {
205                 of_spin_map = cpu_present_map;
206         }
207
208         cpu_clear(boot_cpuid, of_spin_map);
209
210         /* Non-lpar has additional take/give timebase */
211         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
212                 smp_ops->give_timebase = pSeries_give_timebase;
213                 smp_ops->take_timebase = pSeries_take_timebase;
214         }
215
216         pr_debug(" <- smp_init_pSeries()\n");
217 }
218
219 #ifdef CONFIG_MPIC
220 void __init smp_init_pseries_mpic(void)
221 {
222         smp_ops = &pSeries_mpic_smp_ops;
223
224         smp_init_pseries();
225 }
226 #endif
227
228 void __init smp_init_pseries_xics(void)
229 {
230         smp_ops = &pSeries_xics_smp_ops;
231
232         smp_init_pseries();
233 }