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powerpc/pseries: Only call start-cpu when a CPU is stopped
[karo-tx-linux.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
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/machdep.h>
39 #include <asm/cputable.h>
40 #include <asm/firmware.h>
41 #include <asm/system.h>
42 #include <asm/rtas.h>
43 #include <asm/pSeries_reconfig.h>
44 #include <asm/mpic.h>
45 #include <asm/vdso_datapage.h>
46 #include <asm/cputhreads.h>
47
48 #include "plpar_wrappers.h"
49 #include "pseries.h"
50 #include "xics.h"
51 #include "offline_states.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 /**
61  * smp_startup_cpu() - start the given cpu
62  *
63  * At boot time, there is nothing to do for primary threads which were
64  * started from Open Firmware.  For anything else, call RTAS with the
65  * appropriate start location.
66  *
67  * Returns:
68  *      0       - failure
69  *      1       - success
70  */
71 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
72 {
73         int status;
74         unsigned long start_here = __pa((u32)*((unsigned long *)
75                                                generic_secondary_smp_init));
76         unsigned int pcpu;
77         int start_cpu;
78
79         if (cpu_isset(lcpu, of_spin_map))
80                 /* Already started by OF and sitting in spin loop */
81                 return 1;
82
83         pcpu = get_hard_smp_processor_id(lcpu);
84
85         /* Check to see if the CPU out of FW already for kexec */
86         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
87                 cpu_set(lcpu, of_spin_map);
88                 return 1;
89         }
90
91         /* Fixup atomic count: it exited inside IRQ handler. */
92         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
93
94         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
95                 goto out;
96
97         /* 
98          * If the RTAS start-cpu token does not exist then presume the
99          * cpu is already spinning.
100          */
101         start_cpu = rtas_token("start-cpu");
102         if (start_cpu == RTAS_UNKNOWN_SERVICE)
103                 return 1;
104
105         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
106         if (status != 0) {
107                 printk(KERN_ERR "start-cpu failed: %i\n", status);
108                 return 0;
109         }
110
111 out:
112         return 1;
113 }
114
115 #ifdef CONFIG_XICS
116 static void __devinit smp_xics_setup_cpu(int cpu)
117 {
118         if (cpu != boot_cpuid)
119                 xics_setup_cpu();
120
121         if (firmware_has_feature(FW_FEATURE_SPLPAR))
122                 vpa_init(cpu);
123
124         cpu_clear(cpu, of_spin_map);
125         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
126         set_default_offline_state(cpu);
127
128 }
129 #endif /* CONFIG_XICS */
130
131 static void __devinit smp_pSeries_kick_cpu(int nr)
132 {
133         long rc;
134         unsigned long hcpuid;
135         BUG_ON(nr < 0 || nr >= NR_CPUS);
136
137         if (!smp_startup_cpu(nr))
138                 return;
139
140         /*
141          * The processor is currently spinning, waiting for the
142          * cpu_start field to become non-zero After we set cpu_start,
143          * the processor will continue on to secondary_start
144          */
145         paca[nr].cpu_start = 1;
146
147         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
148
149         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
150                 hcpuid = get_hard_smp_processor_id(nr);
151                 rc = plpar_hcall_norets(H_PROD, hcpuid);
152                 if (rc != H_SUCCESS)
153                         printk(KERN_ERR "Error: Prod to wake up processor %d\
154                                                 Ret= %ld\n", nr, rc);
155         }
156 }
157
158 static int smp_pSeries_cpu_bootable(unsigned int nr)
159 {
160         /* Special case - we inhibit secondary thread startup
161          * during boot if the user requests it.
162          */
163         if (system_state < SYSTEM_RUNNING &&
164             cpu_has_feature(CPU_FTR_SMT) &&
165             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
166                 return 0;
167
168         return 1;
169 }
170 #ifdef CONFIG_MPIC
171 static struct smp_ops_t pSeries_mpic_smp_ops = {
172         .message_pass   = smp_mpic_message_pass,
173         .probe          = smp_mpic_probe,
174         .kick_cpu       = smp_pSeries_kick_cpu,
175         .setup_cpu      = smp_mpic_setup_cpu,
176 };
177 #endif
178 #ifdef CONFIG_XICS
179 static struct smp_ops_t pSeries_xics_smp_ops = {
180         .message_pass   = smp_xics_message_pass,
181         .probe          = smp_xics_probe,
182         .kick_cpu       = smp_pSeries_kick_cpu,
183         .setup_cpu      = smp_xics_setup_cpu,
184         .cpu_bootable   = smp_pSeries_cpu_bootable,
185 };
186 #endif
187
188 /* This is called very early */
189 static void __init smp_init_pseries(void)
190 {
191         int i;
192
193         pr_debug(" -> smp_init_pSeries()\n");
194
195         /* Mark threads which are still spinning in hold loops. */
196         if (cpu_has_feature(CPU_FTR_SMT)) {
197                 for_each_present_cpu(i) { 
198                         if (cpu_thread_in_core(i) == 0)
199                                 cpu_set(i, of_spin_map);
200                 }
201         } else {
202                 of_spin_map = cpu_present_map;
203         }
204
205         cpu_clear(boot_cpuid, of_spin_map);
206
207         /* Non-lpar has additional take/give timebase */
208         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
209                 smp_ops->give_timebase = rtas_give_timebase;
210                 smp_ops->take_timebase = rtas_take_timebase;
211         }
212
213         pr_debug(" <- smp_init_pSeries()\n");
214 }
215
216 #ifdef CONFIG_MPIC
217 void __init smp_init_pseries_mpic(void)
218 {
219         smp_ops = &pSeries_mpic_smp_ops;
220
221         smp_init_pseries();
222 }
223 #endif
224
225 void __init smp_init_pseries_xics(void)
226 {
227         smp_ops = &pSeries_xics_smp_ops;
228
229         smp_init_pseries();
230 }