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>
9 #include <linux/device.h>
11 #include <linux/module.h>
12 #include <linux/errno.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/platform_device.h>
16 #include <asm/uaccess.h>
19 #include <linux/types.h>
20 #include <linux/cdev.h>
22 #include <linux/scx200_gpio.h>
24 #define NAME "scx200_gpio"
27 static struct platform_device *pdev;
29 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
30 MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
31 MODULE_LICENSE("GPL");
33 static int major = 0; /* default to dynamic major */
34 module_param(major, int, 0);
35 MODULE_PARM_DESC(major, "Major device number");
37 extern void scx200_gpio_dump(unsigned index);
39 static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
40 size_t len, loff_t *ppos)
42 unsigned m = iminor(file->f_dentry->d_inode);
45 for (i = 0; i < len; ++i) {
47 if (get_user(c, data + i))
51 scx200_gpio_set(m, 0);
54 scx200_gpio_set(m, 1);
57 printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);
58 scx200_gpio_configure(m, ~1, 1);
61 printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);
62 scx200_gpio_configure(m, ~1, 0);
65 printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m);
66 scx200_gpio_configure(m, ~2, 2);
69 printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m);
70 scx200_gpio_configure(m, ~2, 0);
73 printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);
74 scx200_gpio_configure(m, ~4, 4);
77 printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
78 scx200_gpio_configure(m, ~4, 0);
86 static ssize_t scx200_gpio_read(struct file *file, char __user *buf,
87 size_t len, loff_t *ppos)
89 unsigned m = iminor(file->f_dentry->d_inode);
92 value = scx200_gpio_get(m);
93 if (put_user(value ? '1' : '0', buf))
99 static int scx200_gpio_open(struct inode *inode, struct file *file)
101 unsigned m = iminor(inode);
104 return nonseekable_open(inode, file);
107 static int scx200_gpio_release(struct inode *inode, struct file *file)
113 static struct file_operations scx200_gpio_fops = {
114 .owner = THIS_MODULE,
115 .write = scx200_gpio_write,
116 .read = scx200_gpio_read,
117 .open = scx200_gpio_open,
118 .release = scx200_gpio_release,
121 struct cdev *scx200_devices;
122 static int num_pins = 32;
124 static int __init scx200_gpio_init(void)
127 dev_t dev = MKDEV(major, 0);
129 if (!scx200_gpio_present()) {
130 printk(KERN_ERR NAME ": no SCx200 gpio present\n");
134 /* support dev_dbg() with pdev->dev */
135 pdev = platform_device_alloc(DEVNAME, 0);
139 rc = platform_device_add(pdev);
144 rc = register_chrdev_region(dev, num_pins, "scx200_gpio");
146 rc = alloc_chrdev_region(&dev, 0, num_pins, "scx200_gpio");
150 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
151 goto undo_platform_device_add;
153 scx200_devices = kzalloc(num_pins * sizeof(struct cdev), GFP_KERNEL);
154 if (!scx200_devices) {
156 goto undo_chrdev_region;
158 for (i = 0; i < num_pins; i++) {
159 struct cdev *cdev = &scx200_devices[i];
160 cdev_init(cdev, &scx200_gpio_fops);
161 cdev->owner = THIS_MODULE;
162 rc = cdev_add(cdev, MKDEV(major, i), 1);
163 /* tolerate 'minor' errors */
165 dev_err(&pdev->dev, "Error %d on minor %d", rc, i);
168 return 0; /* succeed */
171 unregister_chrdev_region(dev, num_pins);
172 undo_platform_device_add:
173 platform_device_put(pdev);
179 static void __exit scx200_gpio_cleanup(void)
181 kfree(scx200_devices);
182 unregister_chrdev_region(MKDEV(major, 0), num_pins);
183 platform_device_put(pdev);
184 platform_device_unregister(pdev);
188 module_init(scx200_gpio_init);
189 module_exit(scx200_gpio_cleanup);