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