arch/x86/kernel/topology.c

   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;
  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  */
  60 int __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         cpu_hotplug_driver_lock();
  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                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  76                 } else
  77                         pr_debug("Can't offline CPU%d.\n", cpu);
  78                 break;
  79         case 1:
  80                 ret = cpu_up(cpu);
  81                 if (!ret)
  82                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  83                 else
  84                         pr_debug("Can't online CPU%d.\n", cpu);
  85                 break;
  86         default:
  87                 ret = -EINVAL;
  88         }
  89
  90         cpu_hotplug_driver_unlock();
  91
  92         return ret;
  93 }
  94
  95 static int __init debug_hotplug_cpu(void)
  96 {
  97         _debug_hotplug_cpu(0, 0);
  98         return 0;
  99 }
 100
 101 late_initcall_sync(debug_hotplug_cpu);
 102 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
 103
 104 int __ref arch_register_cpu(int num)
 105 {
 106         struct cpuinfo_x86 *c = &cpu_data(num);
 107
 108         /*
 109          * Currently CPU0 is only hotpluggable on Intel platforms. Other
 110          * vendors can add hotplug support later.
 111          */
 112         if (c->x86_vendor != X86_VENDOR_INTEL)
 113                 cpu0_hotpluggable = 0;
 114
 115         /*
 116          * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
 117          * depends on BSP. PIC interrupts depend on BSP.
 118          *
 119          * If the BSP depencies are under control, one can tell kernel to
 120          * enable BSP hotplug. This basically adds a control file and
 121          * one can attempt to offline BSP.
 122          */
 123         if (num == 0 && cpu0_hotpluggable) {
 124                 unsigned int irq;
 125                 /*
 126                  * We won't take down the boot processor on i386 if some
 127                  * interrupts only are able to be serviced by the BSP in PIC.
 128                  */
 129                 for_each_active_irq(irq) {
 130                         if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
 131                                 cpu0_hotpluggable = 0;
 132                                 break;
 133                         }
 134                 }
 135         }
 136         if (num || cpu0_hotpluggable)
 137                 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
 138
 139         return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
 140 }
 141 EXPORT_SYMBOL(arch_register_cpu);
 142
 143 void arch_unregister_cpu(int num)
 144 {
 145         unregister_cpu(&per_cpu(cpu_devices, num).cpu);
 146 }
 147 EXPORT_SYMBOL(arch_unregister_cpu);
 148 #else /* CONFIG_HOTPLUG_CPU */
 149
 150 static int __init arch_register_cpu(int num)
 151 {
 152         return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
 153 }
 154 #endif /* CONFIG_HOTPLUG_CPU */
 155
 156 static int __init topology_init(void)
 157 {
 158         int i;
 159
 160 #ifdef CONFIG_NUMA
 161         for_each_online_node(i)
 162                 register_one_node(i);
 163 #endif
 164
 165         for_each_present_cpu(i)
 166                 arch_register_cpu(i);
 167
 168         return 0;
 169 }
 170 subsys_initcall(topology_init);