1 /* linux/drivers/char/scx200_gpio.c
3 National Semiconductor SCx200 GPIO driver. Allows a user space
4 process to play with the GPIO pins.
6 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */
8 #include <linux/config.h>
10 #include <linux/module.h>
11 #include <linux/errno.h>
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <asm/uaccess.h>
17 #include <linux/types.h>
18 #include <linux/cdev.h>
20 #include <linux/scx200_gpio.h>
22 #define NAME "scx200_gpio"
24 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
25 MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
26 MODULE_LICENSE("GPL");
28 static int major = 0; /* default to dynamic major */
29 module_param(major, int, 0);
30 MODULE_PARM_DESC(major, "Major device number");
32 extern void scx200_gpio_dump(unsigned index);
34 static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
35 size_t len, loff_t *ppos)
37 unsigned m = iminor(file->f_dentry->d_inode);
40 for (i = 0; i < len; ++i) {
42 if (get_user(c, data + i))
46 scx200_gpio_set(m, 0);
49 scx200_gpio_set(m, 1);
52 printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);
53 scx200_gpio_configure(m, ~1, 1);
56 printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);
57 scx200_gpio_configure(m, ~1, 0);
60 printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m);
61 scx200_gpio_configure(m, ~2, 2);
64 printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m);
65 scx200_gpio_configure(m, ~2, 0);
68 printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);
69 scx200_gpio_configure(m, ~4, 4);
72 printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
73 scx200_gpio_configure(m, ~4, 0);
81 static ssize_t scx200_gpio_read(struct file *file, char __user *buf,
82 size_t len, loff_t *ppos)
84 unsigned m = iminor(file->f_dentry->d_inode);
87 value = scx200_gpio_get(m);
88 if (put_user(value ? '1' : '0', buf))
94 static int scx200_gpio_open(struct inode *inode, struct file *file)
96 unsigned m = iminor(inode);
99 return nonseekable_open(inode, file);
102 static int scx200_gpio_release(struct inode *inode, struct file *file)
108 static struct file_operations scx200_gpio_fops = {
109 .owner = THIS_MODULE,
110 .write = scx200_gpio_write,
111 .read = scx200_gpio_read,
112 .open = scx200_gpio_open,
113 .release = scx200_gpio_release,
116 struct cdev *scx200_devices;
119 static int __init scx200_gpio_init(void)
122 dev_t dev = MKDEV(major, 0);
124 printk(KERN_DEBUG NAME ": NatSemi SCx200 GPIO Driver\n");
126 if (!scx200_gpio_present()) {
127 printk(KERN_ERR NAME ": no SCx200 gpio present\n");
131 rc = register_chrdev_region(dev, num_devs, "scx200_gpio");
133 rc = alloc_chrdev_region(&dev, 0, num_devs, "scx200_gpio");
137 printk(KERN_ERR NAME ": SCx200 chrdev_region: %d\n", rc);
140 scx200_devices = kzalloc(num_devs * sizeof(struct cdev), GFP_KERNEL);
141 if (!scx200_devices) {
145 for (i = 0; i < num_devs; i++) {
146 struct cdev *cdev = &scx200_devices[i];
147 cdev_init(cdev, &scx200_gpio_fops);
148 cdev->owner = THIS_MODULE;
149 cdev->ops = &scx200_gpio_fops;
150 rc = cdev_add(cdev, MKDEV(major, i), 1);
151 /* Fail gracefully if need be */
153 printk(KERN_ERR NAME "Error %d on minor %d", rc, i);
156 return 0; /* succeed */
159 unregister_chrdev_region(dev, num_devs);
163 static void __exit scx200_gpio_cleanup(void)
165 kfree(scx200_devices);
166 unregister_chrdev_region(MKDEV(major, 0), num_devs);
169 module_init(scx200_gpio_init);
170 module_exit(scx200_gpio_cleanup);