[POWERPC] Cleanup pseries smp initialisation code
[linux-2.6.git] / 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 #undef DEBUG
16
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/sched.h>
20 #include <linux/smp.h>
21 #include <linux/interrupt.h>
22 #include <linux/delay.h>
23 #include <linux/init.h>
24 #include <linux/spinlock.h>
25 #include <linux/cache.h>
26 #include <linux/err.h>
27 #include <linux/sysdev.h>
28 #include <linux/cpu.h>
29
30 #include <asm/ptrace.h>
31 #include <asm/atomic.h>
32 #include <asm/irq.h>
33 #include <asm/page.h>
34 #include <asm/pgtable.h>
35 #include <asm/io.h>
36 #include <asm/prom.h>
37 #include <asm/smp.h>
38 #include <asm/paca.h>
39 #include <asm/time.h>
40 #include <asm/machdep.h>
41 #include "xics.h"
42 #include <asm/cputable.h>
43 #include <asm/firmware.h>
44 #include <asm/system.h>
45 #include <asm/rtas.h>
46 #include <asm/pSeries_reconfig.h>
47 #include <asm/mpic.h>
48 #include <asm/vdso_datapage.h>
49
50 #include "plpar_wrappers.h"
51 #include "pseries.h"
52
53 #ifdef DEBUG
54 #include <asm/udbg.h>
55 #define DBG(fmt...) udbg_printf(fmt)
56 #else
57 #define DBG(fmt...)
58 #endif
59
60 /*
61  * The primary thread of each non-boot processor is recorded here before
62  * smp init.
63  */
64 static cpumask_t of_spin_map;
65
66 extern void generic_secondary_smp_init(unsigned long);
67
68 /**
69  * smp_startup_cpu() - start the given cpu
70  *
71  * At boot time, there is nothing to do for primary threads which were
72  * started from Open Firmware.  For anything else, call RTAS with the
73  * appropriate start location.
74  *
75  * Returns:
76  *      0       - failure
77  *      1       - success
78  */
79 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
80 {
81         int status;
82         unsigned long start_here = __pa((u32)*((unsigned long *)
83                                                generic_secondary_smp_init));
84         unsigned int pcpu;
85         int start_cpu;
86
87         if (cpu_isset(lcpu, of_spin_map))
88                 /* Already started by OF and sitting in spin loop */
89                 return 1;
90
91         pcpu = get_hard_smp_processor_id(lcpu);
92
93         /* Fixup atomic count: it exited inside IRQ handler. */
94         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
95
96         /* 
97          * If the RTAS start-cpu token does not exist then presume the
98          * cpu is already spinning.
99          */
100         start_cpu = rtas_token("start-cpu");
101         if (start_cpu == RTAS_UNKNOWN_SERVICE)
102                 return 1;
103
104         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
105         if (status != 0) {
106                 printk(KERN_ERR "start-cpu failed: %i\n", status);
107                 return 0;
108         }
109
110         return 1;
111 }
112
113 #ifdef CONFIG_XICS
114 static inline void smp_xics_do_message(int cpu, int msg)
115 {
116         set_bit(msg, &xics_ipi_message[cpu].value);
117         mb();
118         xics_cause_IPI(cpu);
119 }
120
121 static void smp_xics_message_pass(int target, int msg)
122 {
123         unsigned int i;
124
125         if (target < NR_CPUS) {
126                 smp_xics_do_message(target, msg);
127         } else {
128                 for_each_online_cpu(i) {
129                         if (target == MSG_ALL_BUT_SELF
130                             && i == smp_processor_id())
131                                 continue;
132                         smp_xics_do_message(i, msg);
133                 }
134         }
135 }
136
137 static int __init smp_xics_probe(void)
138 {
139         xics_request_IPIs();
140
141         return cpus_weight(cpu_possible_map);
142 }
143
144 static void __devinit smp_xics_setup_cpu(int cpu)
145 {
146         if (cpu != boot_cpuid)
147                 xics_setup_cpu();
148
149         if (firmware_has_feature(FW_FEATURE_SPLPAR))
150                 vpa_init(cpu);
151
152         cpu_clear(cpu, of_spin_map);
153
154 }
155 #endif /* CONFIG_XICS */
156
157 static DEFINE_SPINLOCK(timebase_lock);
158 static unsigned long timebase = 0;
159
160 static void __devinit pSeries_give_timebase(void)
161 {
162         spin_lock(&timebase_lock);
163         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
164         timebase = get_tb();
165         spin_unlock(&timebase_lock);
166
167         while (timebase)
168                 barrier();
169         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
170 }
171
172 static void __devinit pSeries_take_timebase(void)
173 {
174         while (!timebase)
175                 barrier();
176         spin_lock(&timebase_lock);
177         set_tb(timebase >> 32, timebase & 0xffffffff);
178         timebase = 0;
179         spin_unlock(&timebase_lock);
180 }
181
182 static void __devinit smp_pSeries_kick_cpu(int nr)
183 {
184         BUG_ON(nr < 0 || nr >= NR_CPUS);
185
186         if (!smp_startup_cpu(nr))
187                 return;
188
189         /*
190          * The processor is currently spinning, waiting for the
191          * cpu_start field to become non-zero After we set cpu_start,
192          * the processor will continue on to secondary_start
193          */
194         paca[nr].cpu_start = 1;
195 }
196
197 static int smp_pSeries_cpu_bootable(unsigned int nr)
198 {
199         /* Special case - we inhibit secondary thread startup
200          * during boot if the user requests it.  Odd-numbered
201          * cpus are assumed to be secondary threads.
202          */
203         if (system_state < SYSTEM_RUNNING &&
204             cpu_has_feature(CPU_FTR_SMT) &&
205             !smt_enabled_at_boot && nr % 2 != 0)
206                 return 0;
207
208         return 1;
209 }
210 #ifdef CONFIG_MPIC
211 static struct smp_ops_t pSeries_mpic_smp_ops = {
212         .message_pass   = smp_mpic_message_pass,
213         .probe          = smp_mpic_probe,
214         .kick_cpu       = smp_pSeries_kick_cpu,
215         .setup_cpu      = smp_mpic_setup_cpu,
216 };
217 #endif
218 #ifdef CONFIG_XICS
219 static struct smp_ops_t pSeries_xics_smp_ops = {
220         .message_pass   = smp_xics_message_pass,
221         .probe          = smp_xics_probe,
222         .kick_cpu       = smp_pSeries_kick_cpu,
223         .setup_cpu      = smp_xics_setup_cpu,
224         .cpu_bootable   = smp_pSeries_cpu_bootable,
225 };
226 #endif
227
228 /* This is called very early */
229 static void __init smp_init_pseries(void)
230 {
231         int i;
232
233         DBG(" -> smp_init_pSeries()\n");
234
235         /* Mark threads which are still spinning in hold loops. */
236         if (cpu_has_feature(CPU_FTR_SMT)) {
237                 for_each_present_cpu(i) { 
238                         if (i % 2 == 0)
239                                 /*
240                                  * Even-numbered logical cpus correspond to
241                                  * primary threads.
242                                  */
243                                 cpu_set(i, of_spin_map);
244                 }
245         } else {
246                 of_spin_map = cpu_present_map;
247         }
248
249         cpu_clear(boot_cpuid, of_spin_map);
250
251         /* Non-lpar has additional take/give timebase */
252         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
253                 smp_ops->give_timebase = pSeries_give_timebase;
254                 smp_ops->take_timebase = pSeries_take_timebase;
255         }
256
257         DBG(" <- smp_init_pSeries()\n");
258 }
259
260 #ifdef CONFIG_MPIC
261 void __init smp_init_pseries_mpic(void)
262 {
263         smp_ops = &pSeries_mpic_smp_ops;
264
265         smp_init_pseries();
266 }
267 #endif
268
269 void __init smp_init_pseries_xics(void)
270 {
271         smp_ops = &pSeries_xics_smp_ops;
272
273         smp_init_pseries();
274 }