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Linux/arch/powerpc/platforms/pseries/smp.c

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  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/sched.h>
 18 #include <linux/smp.h>
 19 #include <linux/interrupt.h>
 20 #include <linux/delay.h>
 21 #include <linux/init.h>
 22 #include <linux/spinlock.h>
 23 #include <linux/cache.h>
 24 #include <linux/err.h>
 25 #include <linux/device.h>
 26 #include <linux/cpu.h>
 27 
 28 #include <asm/ptrace.h>
 29 #include <linux/atomic.h>
 30 #include <asm/irq.h>
 31 #include <asm/page.h>
 32 #include <asm/pgtable.h>
 33 #include <asm/io.h>
 34 #include <asm/prom.h>
 35 #include <asm/smp.h>
 36 #include <asm/paca.h>
 37 #include <asm/machdep.h>
 38 #include <asm/cputable.h>
 39 #include <asm/firmware.h>
 40 #include <asm/rtas.h>
 41 #include <asm/mpic.h>
 42 #include <asm/vdso_datapage.h>
 43 #include <asm/cputhreads.h>
 44 #include <asm/xics.h>
 45 #include <asm/dbell.h>
 46 #include <asm/plpar_wrappers.h>
 47 
 48 #include "pseries.h"
 49 #include "offline_states.h"
 50 
 51 
 52 /*
 53  * The Primary thread of each non-boot processor was started from the OF client
 54  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
 55  */
 56 static cpumask_var_t of_spin_mask;
 57 
 58 /*
 59  * If we multiplex IPI mechanisms, store the appropriate XICS IPI mechanism here
 60  */
 61 static void  (*xics_cause_ipi)(int cpu, unsigned long data);
 62 
 63 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
 64 int smp_query_cpu_stopped(unsigned int pcpu)
 65 {
 66         int cpu_status, status;
 67         int qcss_tok = rtas_token("query-cpu-stopped-state");
 68 
 69         if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
 70                 printk_once(KERN_INFO
 71                         "Firmware doesn't support query-cpu-stopped-state\n");
 72                 return QCSS_HARDWARE_ERROR;
 73         }
 74 
 75         status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
 76         if (status != 0) {
 77                 printk(KERN_ERR
 78                        "RTAS query-cpu-stopped-state failed: %i\n", status);
 79                 return status;
 80         }
 81 
 82         return cpu_status;
 83 }
 84 
 85 /**
 86  * smp_startup_cpu() - start the given cpu
 87  *
 88  * At boot time, there is nothing to do for primary threads which were
 89  * started from Open Firmware.  For anything else, call RTAS with the
 90  * appropriate start location.
 91  *
 92  * Returns:
 93  *      0       - failure
 94  *      1       - success
 95  */
 96 static inline int smp_startup_cpu(unsigned int lcpu)
 97 {
 98         int status;
 99         unsigned long start_here = __pa((u32)*((unsigned long *)
100                                                generic_secondary_smp_init));
101         unsigned int pcpu;
102         int start_cpu;
103 
104         if (cpumask_test_cpu(lcpu, of_spin_mask))
105                 /* Already started by OF and sitting in spin loop */
106                 return 1;
107 
108         pcpu = get_hard_smp_processor_id(lcpu);
109 
110         /* Check to see if the CPU out of FW already for kexec */
111         if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
112                 cpumask_set_cpu(lcpu, of_spin_mask);
113                 return 1;
114         }
115 
116         /* Fixup atomic count: it exited inside IRQ handler. */
117         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
118 #ifdef CONFIG_HOTPLUG_CPU
119         if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
120                 goto out;
121 #endif
122         /* 
123          * If the RTAS start-cpu token does not exist then presume the
124          * cpu is already spinning.
125          */
126         start_cpu = rtas_token("start-cpu");
127         if (start_cpu == RTAS_UNKNOWN_SERVICE)
128                 return 1;
129 
130         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
131         if (status != 0) {
132                 printk(KERN_ERR "start-cpu failed: %i\n", status);
133                 return 0;
134         }
135 
136 #ifdef CONFIG_HOTPLUG_CPU
137 out:
138 #endif
139         return 1;
140 }
141 
142 static void smp_xics_setup_cpu(int cpu)
143 {
144         if (cpu != boot_cpuid)
145                 xics_setup_cpu();
146         if (cpu_has_feature(CPU_FTR_DBELL))
147                 doorbell_setup_this_cpu();
148 
149         if (firmware_has_feature(FW_FEATURE_SPLPAR))
150                 vpa_init(cpu);
151 
152         cpumask_clear_cpu(cpu, of_spin_mask);
153 #ifdef CONFIG_HOTPLUG_CPU
154         set_cpu_current_state(cpu, CPU_STATE_ONLINE);
155         set_default_offline_state(cpu);
156 #endif
157 }
158 
159 static int smp_pSeries_kick_cpu(int nr)
160 {
161         BUG_ON(nr < 0 || nr >= NR_CPUS);
162 
163         if (!smp_startup_cpu(nr))
164                 return -ENOENT;
165 
166         /*
167          * The processor is currently spinning, waiting for the
168          * cpu_start field to become non-zero After we set cpu_start,
169          * the processor will continue on to secondary_start
170          */
171         paca[nr].cpu_start = 1;
172 #ifdef CONFIG_HOTPLUG_CPU
173         set_preferred_offline_state(nr, CPU_STATE_ONLINE);
174 
175         if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
176                 long rc;
177                 unsigned long hcpuid;
178 
179                 hcpuid = get_hard_smp_processor_id(nr);
180                 rc = plpar_hcall_norets(H_PROD, hcpuid);
181                 if (rc != H_SUCCESS)
182                         printk(KERN_ERR "Error: Prod to wake up processor %d "
183                                                 "Ret= %ld\n", nr, rc);
184         }
185 #endif
186 
187         return 0;
188 }
189 
190 /* Only used on systems that support multiple IPI mechanisms */
191 static void pSeries_cause_ipi_mux(int cpu, unsigned long data)
192 {
193         if (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))
194                 doorbell_cause_ipi(cpu, data);
195         else
196                 xics_cause_ipi(cpu, data);
197 }
198 
199 static __init int pSeries_smp_probe(void)
200 {
201         int ret = xics_smp_probe();
202 
203         if (cpu_has_feature(CPU_FTR_DBELL)) {
204                 xics_cause_ipi = smp_ops->cause_ipi;
205                 smp_ops->cause_ipi = pSeries_cause_ipi_mux;
206         }
207 
208         return ret;
209 }
210 
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 
218 static struct smp_ops_t pSeries_xics_smp_ops = {
219         .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
220         .cause_ipi      = NULL, /* Filled at runtime by pSeries_smp_probe() */
221         .probe          = pSeries_smp_probe,
222         .kick_cpu       = smp_pSeries_kick_cpu,
223         .setup_cpu      = smp_xics_setup_cpu,
224         .cpu_bootable   = smp_generic_cpu_bootable,
225 };
226 
227 /* This is called very early */
228 static void __init smp_init_pseries(void)
229 {
230         int i;
231 
232         pr_debug(" -> smp_init_pSeries()\n");
233 
234         alloc_bootmem_cpumask_var(&of_spin_mask);
235 
236         /*
237          * Mark threads which are still spinning in hold loops
238          *
239          * We know prom_init will not have started them if RTAS supports
240          * query-cpu-stopped-state.
241          */
242         if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
243                 if (cpu_has_feature(CPU_FTR_SMT)) {
244                         for_each_present_cpu(i) {
245                                 if (cpu_thread_in_core(i) == 0)
246                                         cpumask_set_cpu(i, of_spin_mask);
247                         }
248                 } else
249                         cpumask_copy(of_spin_mask, cpu_present_mask);
250 
251                 cpumask_clear_cpu(boot_cpuid, of_spin_mask);
252         }
253 
254         /* Non-lpar has additional take/give timebase */
255         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
256                 smp_ops->give_timebase = rtas_give_timebase;
257                 smp_ops->take_timebase = rtas_take_timebase;
258         }
259 
260         pr_debug(" <- smp_init_pSeries()\n");
261 }
262 
263 void __init smp_init_pseries_mpic(void)
264 {
265         smp_ops = &pSeries_mpic_smp_ops;
266 
267         smp_init_pseries();
268 }
269 
270 void __init smp_init_pseries_xics(void)
271 {
272         smp_ops = &pSeries_xics_smp_ops;
273 
274         smp_init_pseries();
275 }
276 

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