/* * drivers/base/cpu.c - basic CPU class support */ #include <linux/sysdev.h>#include <linux/module.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/cpu.h>#include <linux/topology.h>#include <linux/device.h>#include <linux/node.h> #include "base.h" struct sysdev_class cpu_sysdev_class = {	set_kset_name("cpu"),};EXPORT_SYMBOL(cpu_sysdev_class); static struct sys_device *cpu_sys_devices[NR_CPUS]; #ifdef CONFIG_HOTPLUG_CPUstatic ssize_t show_online(struct sys_device *dev, char *buf){	struct cpu *cpu = container_of(dev, struct cpu, sysdev); 	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));} static ssize_t store_online(struct sys_device *dev, const char *buf,			    size_t count){	struct cpu *cpu = container_of(dev, struct cpu, sysdev);	ssize_t ret; 	switch (buf[0]) {	case '0':		ret = cpu_down(cpu->sysdev.id);		if (!ret)			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);		break;	case '1':		ret = cpu_up(cpu->sysdev.id);		if (!ret)			kobject_uevent(&dev->kobj, KOBJ_ONLINE);		break;	default:		ret = -EINVAL;	} 	if (ret >= 0)		ret = count;	return ret;}static SYSDEV_ATTR(online, 0600, show_online, store_online); static void __devinit register_cpu_control(struct cpu *cpu){	sysdev_create_file(&cpu->sysdev, &attr_online);}void unregister_cpu(struct cpu *cpu){	int logical_cpu = cpu->sysdev.id; 	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 	sysdev_remove_file(&cpu->sysdev, &attr_online); 	sysdev_unregister(&cpu->sysdev);	cpu_sys_devices[logical_cpu] = NULL;	return;}#else /* ... !CONFIG_HOTPLUG_CPU */static inline void register_cpu_control(struct cpu *cpu){}#endif /* CONFIG_HOTPLUG_CPU */ #ifdef CONFIG_KEXEC#include <linux/kexec.h> static ssize_t show_crash_notes(struct sys_device *dev, char *buf){	struct cpu *cpu = container_of(dev, struct cpu, sysdev);	ssize_t rc;	unsigned long long addr;	int cpunum; 	cpunum = cpu->sysdev.id; 	/*	 * Might be reading other cpu's data based on which cpu read thread	 * has been scheduled. But cpu data (memory) is allocated once during	 * boot up and this data does not change there after. Hence this	 * operation should be safe. No locking required.	 */	addr = __pa(per_cpu_ptr(crash_notes, cpunum));	rc = sprintf(buf, "%Lx\n", addr);	return rc;}static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);#endif /* * register_cpu - Setup a sysfs device for a CPU. * @cpu - cpu->hotpluggable field set to 1 will generate a control file in *	  sysfs for this CPU. * @num - CPU number to use when creating the device. * * Initialize and register the CPU device. */int __devinit register_cpu(struct cpu *cpu, int num){	int error;	cpu->node_id = cpu_to_node(num);	cpu->sysdev.id = num;	cpu->sysdev.cls = &cpu_sysdev_class; 	error = sysdev_register(&cpu->sysdev); 	if (!error && cpu->hotpluggable)		register_cpu_control(cpu);	if (!error)		cpu_sys_devices[num] = &cpu->sysdev;	if (!error)		register_cpu_under_node(num, cpu_to_node(num)); #ifdef CONFIG_KEXEC	if (!error)		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);#endif	return error;} struct sys_device *get_cpu_sysdev(unsigned cpu){	if (cpu < NR_CPUS)		return cpu_sys_devices[cpu];	else		return NULL;}EXPORT_SYMBOL_GPL(get_cpu_sysdev); int __init cpu_dev_init(void){	int err; 	err = sysdev_class_register(&cpu_sysdev_class);#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)	if (!err)		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);#endif 	return err;}