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);