Merge git://oss.sgi.com:8090/oss/git/xfs-2.6
[linux-2.6] / arch / powerpc / platforms / cell / smp.c
1 /*
2  * SMP support for BPA 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/config.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/sched.h>
21 #include <linux/smp.h>
22 #include <linux/interrupt.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/spinlock.h>
26 #include <linux/cache.h>
27 #include <linux/err.h>
28 #include <linux/sysdev.h>
29 #include <linux/cpu.h>
30
31 #include <asm/ptrace.h>
32 #include <asm/atomic.h>
33 #include <asm/irq.h>
34 #include <asm/page.h>
35 #include <asm/pgtable.h>
36 #include <asm/io.h>
37 #include <asm/prom.h>
38 #include <asm/smp.h>
39 #include <asm/paca.h>
40 #include <asm/time.h>
41 #include <asm/machdep.h>
42 #include <asm/cputable.h>
43 #include <asm/firmware.h>
44 #include <asm/system.h>
45 #include <asm/rtas.h>
46
47 #include "interrupt.h"
48
49 #ifdef DEBUG
50 #define DBG(fmt...) udbg_printf(fmt)
51 #else
52 #define DBG(fmt...)
53 #endif
54
55 /*
56  * The primary thread of each non-boot processor is recorded here before
57  * smp init.
58  */
59 static cpumask_t of_spin_map;
60
61 extern void pSeries_secondary_smp_init(unsigned long);
62
63 /**
64  * smp_startup_cpu() - start the given cpu
65  *
66  * At boot time, there is nothing to do for primary threads which were
67  * started from Open Firmware.  For anything else, call RTAS with the
68  * appropriate start location.
69  *
70  * Returns:
71  *      0       - failure
72  *      1       - success
73  */
74 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
75 {
76         int status;
77         unsigned long start_here = __pa((u32)*((unsigned long *)
78                                                pSeries_secondary_smp_init));
79         unsigned int pcpu;
80         int start_cpu;
81
82         if (cpu_isset(lcpu, of_spin_map))
83                 /* Already started by OF and sitting in spin loop */
84                 return 1;
85
86         pcpu = get_hard_smp_processor_id(lcpu);
87
88         /* Fixup atomic count: it exited inside IRQ handler. */
89         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
90
91         /*
92          * If the RTAS start-cpu token does not exist then presume the
93          * cpu is already spinning.
94          */
95         start_cpu = rtas_token("start-cpu");
96         if (start_cpu == RTAS_UNKNOWN_SERVICE)
97                 return 1;
98
99         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
100         if (status != 0) {
101                 printk(KERN_ERR "start-cpu failed: %i\n", status);
102                 return 0;
103         }
104
105         return 1;
106 }
107
108 static void smp_iic_message_pass(int target, int msg)
109 {
110         unsigned int i;
111
112         if (target < NR_CPUS) {
113                 iic_cause_IPI(target, msg);
114         } else {
115                 for_each_online_cpu(i) {
116                         if (target == MSG_ALL_BUT_SELF
117                             && i == smp_processor_id())
118                                 continue;
119                         iic_cause_IPI(i, msg);
120                 }
121         }
122 }
123
124 static int __init smp_iic_probe(void)
125 {
126         iic_request_IPIs();
127
128         return cpus_weight(cpu_possible_map);
129 }
130
131 static void __devinit smp_iic_setup_cpu(int cpu)
132 {
133         if (cpu != boot_cpuid)
134                 iic_setup_cpu();
135 }
136
137 static DEFINE_SPINLOCK(timebase_lock);
138 static unsigned long timebase = 0;
139
140 static void __devinit cell_give_timebase(void)
141 {
142         spin_lock(&timebase_lock);
143         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
144         timebase = get_tb();
145         spin_unlock(&timebase_lock);
146
147         while (timebase)
148                 barrier();
149         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
150 }
151
152 static void __devinit cell_take_timebase(void)
153 {
154         while (!timebase)
155                 barrier();
156         spin_lock(&timebase_lock);
157         set_tb(timebase >> 32, timebase & 0xffffffff);
158         timebase = 0;
159         spin_unlock(&timebase_lock);
160 }
161
162 static void __devinit smp_cell_kick_cpu(int nr)
163 {
164         BUG_ON(nr < 0 || nr >= NR_CPUS);
165
166         if (!smp_startup_cpu(nr))
167                 return;
168
169         /*
170          * The processor is currently spinning, waiting for the
171          * cpu_start field to become non-zero After we set cpu_start,
172          * the processor will continue on to secondary_start
173          */
174         paca[nr].cpu_start = 1;
175 }
176
177 static int smp_cell_cpu_bootable(unsigned int nr)
178 {
179         /* Special case - we inhibit secondary thread startup
180          * during boot if the user requests it.  Odd-numbered
181          * cpus are assumed to be secondary threads.
182          */
183         if (system_state < SYSTEM_RUNNING &&
184             cpu_has_feature(CPU_FTR_SMT) &&
185             !smt_enabled_at_boot && nr % 2 != 0)
186                 return 0;
187
188         return 1;
189 }
190 static struct smp_ops_t bpa_iic_smp_ops = {
191         .message_pass   = smp_iic_message_pass,
192         .probe          = smp_iic_probe,
193         .kick_cpu       = smp_cell_kick_cpu,
194         .setup_cpu      = smp_iic_setup_cpu,
195         .cpu_bootable   = smp_cell_cpu_bootable,
196 };
197
198 /* This is called very early */
199 void __init smp_init_cell(void)
200 {
201         int i;
202
203         DBG(" -> smp_init_cell()\n");
204
205         smp_ops = &bpa_iic_smp_ops;
206
207         /* Mark threads which are still spinning in hold loops. */
208         if (cpu_has_feature(CPU_FTR_SMT)) {
209                 for_each_present_cpu(i) {
210                         if (i % 2 == 0)
211                                 /*
212                                  * Even-numbered logical cpus correspond to
213                                  * primary threads.
214                                  */
215                                 cpu_set(i, of_spin_map);
216                 }
217         } else {
218                 of_spin_map = cpu_present_map;
219         }
220
221         cpu_clear(boot_cpuid, of_spin_map);
222
223         /* Non-lpar has additional take/give timebase */
224         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
225                 smp_ops->give_timebase = cell_give_timebase;
226                 smp_ops->take_timebase = cell_take_timebase;
227         }
228
229         DBG(" <- smp_init_cell()\n");
230 }