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 _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("DEBUG_HOTPLUG_CPU0: 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 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 */ 106 107 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); 147 148 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 */ 154 155 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 */ 160 161 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