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
36static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
37
38#ifdef CONFIG_HOTPLUG_CPU
39
40#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
41static int cpu0_hotpluggable = 1;
42#else
43static int cpu0_hotpluggable;
44static 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 */
60int __ref _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
98static int __init debug_hotplug_cpu(void)
99{
100	_debug_hotplug_cpu(0, 0);
101	return 0;
102}
103
104late_initcall_sync(debug_hotplug_cpu);
105#endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
106
107int __ref 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	 */
115	if (c->x86_vendor != X86_VENDOR_INTEL)
116		cpu0_hotpluggable = 0;
117
118	/*
119	 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
120	 * depends on BSP. PIC interrupts depend on BSP.
121	 *
122	 * If the BSP depencies are under control, one can tell kernel to
123	 * enable BSP hotplug. This basically adds a control file and
124	 * one can attempt to offline BSP.
125	 */
126	if (num == 0 && cpu0_hotpluggable) {
127		unsigned int irq;
128		/*
129		 * We won't take down the boot processor on i386 if some
130		 * interrupts only are able to be serviced by the BSP in PIC.
131		 */
132		for_each_active_irq(irq) {
133			if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
134				cpu0_hotpluggable = 0;
135				break;
136			}
137		}
138	}
139	if (num || cpu0_hotpluggable)
140		per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
141
142	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
143}
144EXPORT_SYMBOL(arch_register_cpu);
145
146void arch_unregister_cpu(int num)
147{
148	unregister_cpu(&per_cpu(cpu_devices, num).cpu);
149}
150EXPORT_SYMBOL(arch_unregister_cpu);
151#else /* CONFIG_HOTPLUG_CPU */
152
153static int __init arch_register_cpu(int num)
154{
155	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
156}
157#endif /* CONFIG_HOTPLUG_CPU */
158
159static int __init topology_init(void)
160{
161	int i;
162
163#ifdef CONFIG_NUMA
164	for_each_online_node(i)
165		register_one_node(i);
166#endif
167
168	for_each_present_cpu(i)
169		arch_register_cpu(i);
170
171	return 0;
172}
173subsys_initcall(topology_init);
174