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/* linux/drivers/char/scx200_gpio.c
National Semiconductor SCx200 GPIO driver. Allows a user space
process to play with the GPIO pins.
Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */
#include <linux/config.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/scx200_gpio.h>
#define NAME "scx200_gpio"
MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
MODULE_LICENSE("GPL");
static int major = 0; /* default to dynamic major */
module_param(major, int, 0);
MODULE_PARM_DESC(major, "Major device number");
static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
unsigned m = iminor(file->f_dentry->d_inode);
size_t i;
for (i = 0; i < len; ++i) {
char c;
if (get_user(c, data + i))
return -EFAULT;
switch (c) {
case '0':
scx200_gpio_set(m, 0);
break;
case '1':
scx200_gpio_set(m, 1);
break;
case 'O':
printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);
scx200_gpio_configure(m, ~1, 1);
break;
case 'o':
printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);
scx200_gpio_configure(m, ~1, 0);
break;
case 'T':
printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m);
scx200_gpio_configure(m, ~2, 2);
break;
case 't':
printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m);
scx200_gpio_configure(m, ~2, 0);
break;
case 'P':
printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);
scx200_gpio_configure(m, ~4, 4);
break;
case 'p':
printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
scx200_gpio_configure(m, ~4, 0);
break;
}
}
return len;
}
static ssize_t scx200_gpio_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
unsigned m = iminor(file->f_dentry->d_inode);
int value;
value = scx200_gpio_get(m);
if (put_user(value ? '1' : '0', buf))
return -EFAULT;
return 1;
}
static int scx200_gpio_open(struct inode *inode, struct file *file)
{
unsigned m = iminor(inode);
if (m > 63)
return -EINVAL;
return nonseekable_open(inode, file);
}
static int scx200_gpio_release(struct inode *inode, struct file *file)
{
return 0;
}
static struct file_operations scx200_gpio_fops = {
.owner = THIS_MODULE,
.write = scx200_gpio_write,
.read = scx200_gpio_read,
.open = scx200_gpio_open,
.release = scx200_gpio_release,
};
static int __init scx200_gpio_init(void)
{
int r;
printk(KERN_DEBUG NAME ": NatSemi SCx200 GPIO Driver\n");
if (!scx200_gpio_present()) {
printk(KERN_ERR NAME ": no SCx200 gpio pins available\n");
return -ENODEV;
}
r = register_chrdev(major, NAME, &scx200_gpio_fops);
if (r < 0) {
printk(KERN_ERR NAME ": unable to register character device\n");
return r;
}
if (!major) {
major = r;
printk(KERN_DEBUG NAME ": got dynamic major %d\n", major);
}
return 0;
}
static void __exit scx200_gpio_cleanup(void)
{
unregister_chrdev(major, NAME);
}
module_init(scx200_gpio_init);
module_exit(scx200_gpio_cleanup);
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