1 /*
2 * Populate sysfs with topology information
3 *
4 * Written by: Matthew Dobson, IBM Corporation
5 * Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
6 *
7 * Copyright (C) 2002, IBM Corp.
8 *
9 * All rights reserved.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
19 * NON INFRINGEMENT. See the GNU General Public License for more
20 * details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 *
26 * Send feedback to <colpatch@us.ibm.com>
27 */
28 #include <linux/nodemask.h>
29 #include <linux/export.h>
30 #include <linux/mmzone.h>
31 #include <linux/init.h>
32 #include <linux/smp.h>
33 #include <linux/irq.h>
34 #include <asm/cpu.h>
35
36 static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
37
38 #ifdef CONFIG_HOTPLUG_CPU
39
40 #ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
41 static int cpu0_hotpluggable = 1;
42 #else
43 static int cpu0_hotpluggable;
enable_cpu0_hotplug(char * str)44 static int __init enable_cpu0_hotplug(char *str)
45 {
46 cpu0_hotpluggable = 1;
47 return 1;
48 }
49
50 __setup("cpu0_hotplug", enable_cpu0_hotplug);
51 #endif
52
53 #ifdef CONFIG_DEBUG_HOTPLUG_CPU0
54 /*
55 * This function offlines a CPU as early as possible and allows userspace to
56 * boot up without the CPU. The CPU can be onlined back by user after boot.
57 *
58 * This is only called for debugging CPU offline/online feature.
59 */
_debug_hotplug_cpu(int cpu,int action)60 int _debug_hotplug_cpu(int cpu, int action)
61 {
62 struct device *dev = get_cpu_device(cpu);
63 int ret;
64
65 if (!cpu_is_hotpluggable(cpu))
66 return -EINVAL;
67
68 lock_device_hotplug();
69
70 switch (action) {
71 case 0:
72 ret = cpu_down(cpu);
73 if (!ret) {
74 pr_info("CPU %u is now offline\n", cpu);
75 dev->offline = true;
76 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
77 } else
78 pr_debug("Can't offline CPU%d.\n", cpu);
79 break;
80 case 1:
81 ret = cpu_up(cpu);
82 if (!ret) {
83 dev->offline = false;
84 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
85 } else {
86 pr_debug("Can't online CPU%d.\n", cpu);
87 }
88 break;
89 default:
90 ret = -EINVAL;
91 }
92
93 unlock_device_hotplug();
94
95 return ret;
96 }
97
debug_hotplug_cpu(void)98 static int __init debug_hotplug_cpu(void)
99 {
100 _debug_hotplug_cpu(0, 0);
101 return 0;
102 }
103
104 late_initcall_sync(debug_hotplug_cpu);
105 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
106
arch_register_cpu(int num)107 int arch_register_cpu(int num)
108 {
109 struct cpuinfo_x86 *c = &cpu_data(num);
110
111 /*
112 * Currently CPU0 is only hotpluggable on Intel platforms. Other
113 * vendors can add hotplug support later.
114 * Xen PV guests don't support CPU0 hotplug at all.
115 */
116 if (c->x86_vendor != X86_VENDOR_INTEL ||
117 boot_cpu_has(X86_FEATURE_XENPV))
118 cpu0_hotpluggable = 0;
119
120 /*
121 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
122 * depends on BSP. PIC interrupts depend on BSP.
123 *
124 * If the BSP depencies are under control, one can tell kernel to
125 * enable BSP hotplug. This basically adds a control file and
126 * one can attempt to offline BSP.
127 */
128 if (num == 0 && cpu0_hotpluggable) {
129 unsigned int irq;
130 /*
131 * We won't take down the boot processor on i386 if some
132 * interrupts only are able to be serviced by the BSP in PIC.
133 */
134 for_each_active_irq(irq) {
135 if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
136 cpu0_hotpluggable = 0;
137 break;
138 }
139 }
140 }
141 if (num || cpu0_hotpluggable)
142 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
143
144 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
145 }
146 EXPORT_SYMBOL(arch_register_cpu);
147
arch_unregister_cpu(int num)148 void arch_unregister_cpu(int num)
149 {
150 unregister_cpu(&per_cpu(cpu_devices, num).cpu);
151 }
152 EXPORT_SYMBOL(arch_unregister_cpu);
153 #else /* CONFIG_HOTPLUG_CPU */
154
arch_register_cpu(int num)155 static int __init arch_register_cpu(int num)
156 {
157 return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
158 }
159 #endif /* CONFIG_HOTPLUG_CPU */
160
topology_init(void)161 static int __init topology_init(void)
162 {
163 int i;
164
165 #ifdef CONFIG_NUMA
166 for_each_online_node(i)
167 register_one_node(i);
168 #endif
169
170 for_each_present_cpu(i)
171 arch_register_cpu(i);
172
173 return 0;
174 }
175 subsys_initcall(topology_init);
176
