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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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256 lines
5.4 KiB
C
256 lines
5.4 KiB
C
/*
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* Sky CPU State Driver
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*
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* Copyright (C) 2002 Brian Waite
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*
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* This driver allows use of the CPU state bits
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* It exports the /dev/sky_cpustate and also
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* /proc/sky_cpustate pseudo-file for status information.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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#include <linux/smp_lock.h>
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#include <linux/miscdevice.h>
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#include <linux/proc_fs.h>
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#include <linux/hdpu_features.h>
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#include <linux/platform_device.h>
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#include <asm/uaccess.h>
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#include <linux/seq_file.h>
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#include <asm/io.h>
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#define SKY_CPUSTATE_VERSION "1.1"
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static int hdpu_cpustate_probe(struct platform_device *pdev);
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static int hdpu_cpustate_remove(struct platform_device *pdev);
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static unsigned char cpustate_get_state(void);
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static int cpustate_proc_open(struct inode *inode, struct file *file);
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static int cpustate_proc_read(struct seq_file *seq, void *offset);
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static struct cpustate_t cpustate;
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static const struct file_operations proc_cpustate = {
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.open = cpustate_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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.owner = THIS_MODULE,
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};
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static int cpustate_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, cpustate_proc_read, NULL);
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}
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static int cpustate_proc_read(struct seq_file *seq, void *offset)
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{
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seq_printf(seq, "CPU State: %04x\n", cpustate_get_state());
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return 0;
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}
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static int cpustate_get_ref(int excl)
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{
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int retval = -EBUSY;
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spin_lock(&cpustate.lock);
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if (cpustate.excl)
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goto out_busy;
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if (excl) {
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if (cpustate.open_count)
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goto out_busy;
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cpustate.excl = 1;
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}
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cpustate.open_count++;
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retval = 0;
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out_busy:
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spin_unlock(&cpustate.lock);
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return retval;
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}
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static int cpustate_free_ref(void)
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{
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spin_lock(&cpustate.lock);
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cpustate.excl = 0;
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cpustate.open_count--;
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spin_unlock(&cpustate.lock);
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return 0;
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}
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static unsigned char cpustate_get_state(void)
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{
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return cpustate.cached_val;
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}
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static void cpustate_set_state(unsigned char new_state)
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{
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unsigned int state = (new_state << 21);
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#ifdef DEBUG_CPUSTATE
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printk("CPUSTATE -> 0x%x\n", new_state);
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#endif
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spin_lock(&cpustate.lock);
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cpustate.cached_val = new_state;
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writel((0xff << 21), cpustate.clr_addr);
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writel(state, cpustate.set_addr);
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spin_unlock(&cpustate.lock);
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}
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/*
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* Now all the various file operations that we export.
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*/
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static ssize_t cpustate_read(struct file *file, char *buf,
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size_t count, loff_t * ppos)
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{
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unsigned char data;
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if (count < 0)
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return -EFAULT;
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if (count == 0)
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return 0;
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data = cpustate_get_state();
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if (copy_to_user(buf, &data, sizeof(unsigned char)))
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return -EFAULT;
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return sizeof(unsigned char);
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}
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static ssize_t cpustate_write(struct file *file, const char *buf,
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size_t count, loff_t * ppos)
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{
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unsigned char data;
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if (count < 0)
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return -EFAULT;
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if (count == 0)
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return 0;
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if (copy_from_user((unsigned char *)&data, buf, sizeof(unsigned char)))
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return -EFAULT;
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cpustate_set_state(data);
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return sizeof(unsigned char);
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}
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static int cpustate_open(struct inode *inode, struct file *file)
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{
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int ret;
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lock_kernel();
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ret = cpustate_get_ref((file->f_flags & O_EXCL));
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unlock_kernel();
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return ret;
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}
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static int cpustate_release(struct inode *inode, struct file *file)
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{
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return cpustate_free_ref();
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}
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static struct platform_driver hdpu_cpustate_driver = {
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.probe = hdpu_cpustate_probe,
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.remove = hdpu_cpustate_remove,
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.driver = {
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.name = HDPU_CPUSTATE_NAME,
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.owner = THIS_MODULE,
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},
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};
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/*
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* The various file operations we support.
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*/
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static const struct file_operations cpustate_fops = {
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.owner = THIS_MODULE,
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.open = cpustate_open,
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.release = cpustate_release,
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.read = cpustate_read,
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.write = cpustate_write,
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.llseek = no_llseek,
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};
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static struct miscdevice cpustate_dev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "sky_cpustate",
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.fops = &cpustate_fops,
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};
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static int hdpu_cpustate_probe(struct platform_device *pdev)
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{
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struct resource *res;
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struct proc_dir_entry *proc_de;
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int ret;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!res) {
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printk(KERN_ERR "sky_cpustate: "
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"Invalid memory resource.\n");
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return -EINVAL;
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}
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cpustate.set_addr = (unsigned long *)res->start;
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cpustate.clr_addr = (unsigned long *)res->end - 1;
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ret = misc_register(&cpustate_dev);
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if (ret) {
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printk(KERN_WARNING "sky_cpustate: "
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"Unable to register misc device.\n");
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cpustate.set_addr = NULL;
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cpustate.clr_addr = NULL;
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return ret;
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}
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proc_de = proc_create("sky_cpustate", 0666, NULL, &proc_cpustate);
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if (!proc_de) {
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printk(KERN_WARNING "sky_cpustate: "
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"Unable to create proc entry\n");
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}
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printk(KERN_INFO "Sky CPU State Driver v" SKY_CPUSTATE_VERSION "\n");
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return 0;
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}
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static int hdpu_cpustate_remove(struct platform_device *pdev)
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{
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cpustate.set_addr = NULL;
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cpustate.clr_addr = NULL;
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remove_proc_entry("sky_cpustate", NULL);
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misc_deregister(&cpustate_dev);
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return 0;
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}
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static int __init cpustate_init(void)
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{
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return platform_driver_register(&hdpu_cpustate_driver);
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}
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static void __exit cpustate_exit(void)
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{
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platform_driver_unregister(&hdpu_cpustate_driver);
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}
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module_init(cpustate_init);
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module_exit(cpustate_exit);
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MODULE_AUTHOR("Brian Waite");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:" HDPU_CPUSTATE_NAME);
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