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