1 /*
2 * SMP support for PowerNV machines.
3 *
4 * Copyright 2011 IBM Corp.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/sched.h>
15 #include <linux/smp.h>
16 #include <linux/interrupt.h>
17 #include <linux/delay.h>
18 #include <linux/init.h>
19 #include <linux/spinlock.h>
20 #include <linux/cpu.h>
21
22 #include <asm/irq.h>
23 #include <asm/smp.h>
24 #include <asm/paca.h>
25 #include <asm/machdep.h>
26 #include <asm/cputable.h>
27 #include <asm/firmware.h>
28 #include <asm/rtas.h>
29 #include <asm/vdso_datapage.h>
30 #include <asm/cputhreads.h>
31 #include <asm/xics.h>
32 #include <asm/opal.h>
33 #include <asm/runlatch.h>
34 #include <asm/code-patching.h>
35 #include <asm/dbell.h>
36
37 #include "powernv.h"
38
39 #ifdef DEBUG
40 #include <asm/udbg.h>
41 #define DBG(fmt...) udbg_printf(fmt)
42 #else
43 #define DBG(fmt...)
44 #endif
45
pnv_smp_setup_cpu(int cpu)46 static void pnv_smp_setup_cpu(int cpu)
47 {
48 if (cpu != boot_cpuid)
49 xics_setup_cpu();
50
51 #ifdef CONFIG_PPC_DOORBELL
52 if (cpu_has_feature(CPU_FTR_DBELL))
53 doorbell_setup_this_cpu();
54 #endif
55 }
56
pnv_smp_kick_cpu(int nr)57 static int pnv_smp_kick_cpu(int nr)
58 {
59 unsigned int pcpu = get_hard_smp_processor_id(nr);
60 unsigned long start_here =
61 __pa(ppc_function_entry(generic_secondary_smp_init));
62 long rc;
63
64 BUG_ON(nr < 0 || nr >= NR_CPUS);
65
66 /*
67 * If we already started or OPALv2 is not supported, we just
68 * kick the CPU via the PACA
69 */
70 if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
71 goto kick;
72
73 /*
74 * At this point, the CPU can either be spinning on the way in
75 * from kexec or be inside OPAL waiting to be started for the
76 * first time. OPAL v3 allows us to query OPAL to know if it
77 * has the CPUs, so we do that
78 */
79 if (firmware_has_feature(FW_FEATURE_OPALv3)) {
80 uint8_t status;
81
82 rc = opal_query_cpu_status(pcpu, &status);
83 if (rc != OPAL_SUCCESS) {
84 pr_warn("OPAL Error %ld querying CPU %d state\n",
85 rc, nr);
86 return -ENODEV;
87 }
88
89 /*
90 * Already started, just kick it, probably coming from
91 * kexec and spinning
92 */
93 if (status == OPAL_THREAD_STARTED)
94 goto kick;
95
96 /*
97 * Available/inactive, let's kick it
98 */
99 if (status == OPAL_THREAD_INACTIVE) {
100 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n",
101 nr, pcpu);
102 rc = opal_start_cpu(pcpu, start_here);
103 if (rc != OPAL_SUCCESS) {
104 pr_warn("OPAL Error %ld starting CPU %d\n",
105 rc, nr);
106 return -ENODEV;
107 }
108 } else {
109 /*
110 * An unavailable CPU (or any other unknown status)
111 * shouldn't be started. It should also
112 * not be in the possible map but currently it can
113 * happen
114 */
115 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
116 " (status %d)...\n", nr, pcpu, status);
117 return -ENODEV;
118 }
119 } else {
120 /*
121 * On OPAL v2, we just kick it and hope for the best,
122 * we must not test the error from opal_start_cpu() or
123 * we would fail to get CPUs from kexec.
124 */
125 opal_start_cpu(pcpu, start_here);
126 }
127 kick:
128 return smp_generic_kick_cpu(nr);
129 }
130
131 #ifdef CONFIG_HOTPLUG_CPU
132
pnv_smp_cpu_disable(void)133 static int pnv_smp_cpu_disable(void)
134 {
135 int cpu = smp_processor_id();
136
137 /* This is identical to pSeries... might consolidate by
138 * moving migrate_irqs_away to a ppc_md with default to
139 * the generic fixup_irqs. --BenH.
140 */
141 set_cpu_online(cpu, false);
142 vdso_data->processorCount--;
143 if (cpu == boot_cpuid)
144 boot_cpuid = cpumask_any(cpu_online_mask);
145 xics_migrate_irqs_away();
146 return 0;
147 }
148
pnv_smp_cpu_kill_self(void)149 static void pnv_smp_cpu_kill_self(void)
150 {
151 unsigned int cpu;
152
153 /* Standard hot unplug procedure */
154 local_irq_disable();
155 idle_task_exit();
156 current->active_mm = NULL; /* for sanity */
157 cpu = smp_processor_id();
158 DBG("CPU%d offline\n", cpu);
159 generic_set_cpu_dead(cpu);
160 smp_wmb();
161
162 /* We don't want to take decrementer interrupts while we are offline,
163 * so clear LPCR:PECE1. We keep PECE2 enabled.
164 */
165 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
166 while (!generic_check_cpu_restart(cpu)) {
167 ppc64_runlatch_off();
168 power7_nap(1);
169 ppc64_runlatch_on();
170
171 /* Clear the IPI that woke us up */
172 icp_native_flush_interrupt();
173 local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
174 mb();
175
176 if (cpu_core_split_required())
177 continue;
178
179 if (!generic_check_cpu_restart(cpu))
180 DBG("CPU%d Unexpected exit while offline !\n", cpu);
181 }
182 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
183 DBG("CPU%d coming online...\n", cpu);
184 }
185
186 #endif /* CONFIG_HOTPLUG_CPU */
187
188 static struct smp_ops_t pnv_smp_ops = {
189 .message_pass = smp_muxed_ipi_message_pass,
190 .cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */
191 .probe = xics_smp_probe,
192 .kick_cpu = pnv_smp_kick_cpu,
193 .setup_cpu = pnv_smp_setup_cpu,
194 .cpu_bootable = smp_generic_cpu_bootable,
195 #ifdef CONFIG_HOTPLUG_CPU
196 .cpu_disable = pnv_smp_cpu_disable,
197 .cpu_die = generic_cpu_die,
198 #endif /* CONFIG_HOTPLUG_CPU */
199 };
200
201 /* This is called very early during platform setup_arch */
pnv_smp_init(void)202 void __init pnv_smp_init(void)
203 {
204 smp_ops = &pnv_smp_ops;
205
206 /* XXX We don't yet have a proper entry point from HAL, for
207 * now we rely on kexec-style entry from BML
208 */
209
210 #ifdef CONFIG_PPC_RTAS
211 /* Non-lpar has additional take/give timebase */
212 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
213 smp_ops->give_timebase = rtas_give_timebase;
214 smp_ops->take_timebase = rtas_take_timebase;
215 }
216 #endif /* CONFIG_PPC_RTAS */
217
218 #ifdef CONFIG_HOTPLUG_CPU
219 ppc_md.cpu_die = pnv_smp_cpu_kill_self;
220 #endif
221 }
222