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>
23 #include <linux/nsc_gpio.h>
25 #define NAME "scx200_gpio"
28 static struct platform_device *pdev;
30 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
31 MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
32 MODULE_LICENSE("GPL");
34 static int major = 0; /* default to dynamic major */
35 module_param(major, int, 0);
36 MODULE_PARM_DESC(major, "Major device number");
38 extern void scx200_gpio_dump(unsigned index);
40 struct nsc_gpio_ops scx200_access = {
42 .gpio_config = scx200_gpio_configure,
43 .gpio_dump = scx200_gpio_dump,
44 .gpio_get = scx200_gpio_get,
45 .gpio_set = scx200_gpio_set,
46 .gpio_set_high = scx200_gpio_set_high,
47 .gpio_set_low = scx200_gpio_set_low,
48 .gpio_change = scx200_gpio_change,
49 .gpio_current = scx200_gpio_current
52 static ssize_t scx200_gpio_write(struct file *file, const char __user *data,
53 size_t len, loff_t *ppos)
55 unsigned m = iminor(file->f_dentry->d_inode);
56 struct nsc_gpio_ops *amp = file->private_data;
60 for (i = 0; i < len; ++i) {
62 if (get_user(c, data + i))
72 printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);
73 amp->gpio_config(m, ~1, 1);
76 printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);
77 amp->gpio_config(m, ~1, 0);
80 printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m);
81 amp->gpio_config(m, ~2, 2);
84 printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m);
85 amp->gpio_config(m, ~2, 0);
88 printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);
89 amp->gpio_config(m, ~4, 4);
92 printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);
93 amp->gpio_config(m, ~4, 0);
97 /* View Current pin settings */
101 /* end of settings string, do nothing */
105 ": GPIO-%2d bad setting: chr<0x%2x>\n", m,
111 return -EINVAL; /* full string handled, report error */
116 static ssize_t scx200_gpio_read(struct file *file, char __user *buf,
117 size_t len, loff_t *ppos)
119 unsigned m = iminor(file->f_dentry->d_inode);
121 struct nsc_gpio_ops *amp = file->private_data;
123 value = amp->gpio_get(m);
124 if (put_user(value ? '1' : '0', buf))
130 static int scx200_gpio_open(struct inode *inode, struct file *file)
132 unsigned m = iminor(inode);
133 file->private_data = &scx200_access;
137 return nonseekable_open(inode, file);
140 static int scx200_gpio_release(struct inode *inode, struct file *file)
146 static struct file_operations scx200_gpio_fops = {
147 .owner = THIS_MODULE,
148 .write = scx200_gpio_write,
149 .read = scx200_gpio_read,
150 .open = scx200_gpio_open,
151 .release = scx200_gpio_release,
154 struct cdev *scx200_devices;
155 static int num_pins = 32;
157 static int __init scx200_gpio_init(void)
160 dev_t dev = MKDEV(major, 0);
162 if (!scx200_gpio_present()) {
163 printk(KERN_ERR NAME ": no SCx200 gpio present\n");
167 /* support dev_dbg() with pdev->dev */
168 pdev = platform_device_alloc(DEVNAME, 0);
172 rc = platform_device_add(pdev);
177 rc = register_chrdev_region(dev, num_pins, "scx200_gpio");
179 rc = alloc_chrdev_region(&dev, 0, num_pins, "scx200_gpio");
183 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
184 goto undo_platform_device_add;
186 scx200_devices = kzalloc(num_pins * sizeof(struct cdev), GFP_KERNEL);
187 if (!scx200_devices) {
189 goto undo_chrdev_region;
191 for (i = 0; i < num_pins; i++) {
192 struct cdev *cdev = &scx200_devices[i];
193 cdev_init(cdev, &scx200_gpio_fops);
194 cdev->owner = THIS_MODULE;
195 rc = cdev_add(cdev, MKDEV(major, i), 1);
196 /* tolerate 'minor' errors */
198 dev_err(&pdev->dev, "Error %d on minor %d", rc, i);
201 return 0; /* succeed */
204 unregister_chrdev_region(dev, num_pins);
205 undo_platform_device_add:
206 platform_device_put(pdev);
212 static void __exit scx200_gpio_cleanup(void)
214 kfree(scx200_devices);
215 unregister_chrdev_region(MKDEV(major, 0), num_pins);
216 platform_device_put(pdev);
217 platform_device_unregister(pdev);
221 module_init(scx200_gpio_init);
222 module_exit(scx200_gpio_cleanup);