ad74557a49
Some modules creating sysfs entries under /sys/devices/system/cpu/cpuX/ need to know the parent sysfs entry to make devices under them. This will just return the sysfs entry for a given cpu. sysfs entries showing under each cpu sysfs can be easily created if such entries can be created by registering a sysfs driver for cpuclass. The issue is when the entry is created the CPU may not be online, hence we would need to defer the creation until the online notification comes. Current users: cache entries for Intel CPU's and cpufreq subsystem. Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Zwane Mwaikambo <zwane@holomorphy.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
127 lines
2.8 KiB
C
127 lines
2.8 KiB
C
/*
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* drivers/base/cpu.c - basic CPU class support
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*/
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#include <linux/sysdev.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/cpu.h>
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#include <linux/topology.h>
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#include <linux/device.h>
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#include "base.h"
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struct sysdev_class cpu_sysdev_class = {
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set_kset_name("cpu"),
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};
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EXPORT_SYMBOL(cpu_sysdev_class);
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static struct sys_device *cpu_sys_devices[NR_CPUS];
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#ifdef CONFIG_HOTPLUG_CPU
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int __attribute__((weak)) smp_prepare_cpu (int cpu)
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{
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return 0;
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}
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static ssize_t show_online(struct sys_device *dev, char *buf)
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{
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struct cpu *cpu = container_of(dev, struct cpu, sysdev);
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return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
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}
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static ssize_t store_online(struct sys_device *dev, const char *buf,
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size_t count)
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{
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struct cpu *cpu = container_of(dev, struct cpu, sysdev);
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ssize_t ret;
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switch (buf[0]) {
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case '0':
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ret = cpu_down(cpu->sysdev.id);
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if (!ret)
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kobject_hotplug(&dev->kobj, KOBJ_OFFLINE);
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break;
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case '1':
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ret = smp_prepare_cpu(cpu->sysdev.id);
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if (!ret)
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ret = cpu_up(cpu->sysdev.id);
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if (!ret)
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kobject_hotplug(&dev->kobj, KOBJ_ONLINE);
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break;
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default:
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ret = -EINVAL;
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}
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if (ret >= 0)
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ret = count;
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return ret;
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}
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static SYSDEV_ATTR(online, 0600, show_online, store_online);
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static void __devinit register_cpu_control(struct cpu *cpu)
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{
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sysdev_create_file(&cpu->sysdev, &attr_online);
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}
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void unregister_cpu(struct cpu *cpu, struct node *root)
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{
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int logical_cpu = cpu->sysdev.id;
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if (root)
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sysfs_remove_link(&root->sysdev.kobj,
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kobject_name(&cpu->sysdev.kobj));
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sysdev_remove_file(&cpu->sysdev, &attr_online);
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sysdev_unregister(&cpu->sysdev);
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cpu_sys_devices[logical_cpu] = NULL;
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return;
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}
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#else /* ... !CONFIG_HOTPLUG_CPU */
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static inline void register_cpu_control(struct cpu *cpu)
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{
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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/*
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* register_cpu - Setup a driverfs device for a CPU.
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* @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
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* generate a control file in sysfs for this CPU.
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* @num - CPU number to use when creating the device.
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*
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* Initialize and register the CPU device.
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*/
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int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
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{
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int error;
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cpu->node_id = cpu_to_node(num);
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cpu->sysdev.id = num;
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cpu->sysdev.cls = &cpu_sysdev_class;
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error = sysdev_register(&cpu->sysdev);
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if (!error && root)
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error = sysfs_create_link(&root->sysdev.kobj,
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&cpu->sysdev.kobj,
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kobject_name(&cpu->sysdev.kobj));
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if (!error && !cpu->no_control)
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register_cpu_control(cpu);
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if (!error)
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cpu_sys_devices[num] = &cpu->sysdev;
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return error;
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}
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struct sys_device *get_cpu_sysdev(int cpu)
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{
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if (cpu < NR_CPUS)
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return cpu_sys_devices[cpu];
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else
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return NULL;
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}
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EXPORT_SYMBOL_GPL(get_cpu_sysdev);
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int __init cpu_dev_init(void)
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{
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return sysdev_class_register(&cpu_sysdev_class);
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}
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