1/*
2 * character device wrapper for generic gpio layer
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
17 *
18 * Feedback, Bugs...  blogic@openwrt.org
19 *
20 * dpg 20100106
21 */
22
23#include <linux/module.h>
24#include <linux/errno.h>
25#include <linux/init.h>
26#include <asm/uaccess.h>
27#include <asm/io.h>
28#include <asm/gpio.h>
29#include <asm/atomic.h>
30#include <linux/init.h>
31#include <linux/genhd.h>
32#include <linux/device.h>
33#include <linux/platform_device.h>
34#include <linux/gpio_dev.h>
35#include <linux/fs.h>
36
37#define DRVNAME		"gpiodev"
38#define DEVNAME		"gpio"
39
40static int dev_major;
41static struct class *gpiodev_class;
42
43
44/* third argument of user space ioctl ('arg' here) contains the <pin> */
45static int
46gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
47{
48	int retval = 0;
49
50	switch (cmd)
51	{
52	case GPIO_GET:
53		retval = gpio_get_value(arg);
54		break;
55	case GPIO_SET:
56		gpio_set_value(arg, 1);
57		break;
58	case GPIO_CLEAR:
59		gpio_set_value(arg, 0);
60		break;
61	case GPIO_DIR_IN:
62		retval = gpio_direction_input(arg);
63		break;
64	case GPIO_DIR_OUT:
65		retval = gpio_direction_output(arg, 0);
66		break;
67	case GPIO_DIR_HIGH:
68		retval = gpio_direction_output(arg, 1);
69		break;
70	case GPIO_REQUEST:
71		/* should be first ioctl operation on <pin> */
72		retval = gpio_request(arg, DRVNAME);
73		break;
74	case GPIO_FREE:
75		/* should be last ioctl operation on <pin> */
76		/* may be needed first if previous user missed this ioctl */
77		gpio_free(arg);
78		break;
79	case GPIO_CAN_SLEEP:
80		retval = gpio_cansleep(arg);
81		break;
82	default:
83		retval = -EINVAL;
84		/* = -ENOTTY; // correct return but ... */
85		break;
86	}
87	return retval;
88}
89
90/* Allow co-incident opens */
91static int
92gpio_open(struct inode *inode, struct file *file)
93{
94	int result = 0;
95	unsigned int dev_minor = MINOR(inode->i_rdev);
96
97	if (dev_minor != 0)
98	{
99		printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
100		result = -ENODEV;
101		goto out;
102	}
103out:
104	return result;
105}
106
107static int
108gpio_close(struct inode * inode, struct file * file)
109{
110	/* could track all <pin>s requested by this fd and gpio_free()
111         * them here
112	 */
113	return 0;
114}
115
116struct file_operations gpio_fops = {
117	unlocked_ioctl:	gpio_ioctl,
118	open:		gpio_open,
119	release:	gpio_close
120};
121
122static int
123gpio_probe(struct platform_device *dev)
124{
125	int result = 0;
126
127	dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
128	if (!dev_major)
129	{
130		printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
131		result = -ENODEV;
132		goto out;
133	}
134	gpiodev_class = class_create(THIS_MODULE, DRVNAME);
135	device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME);
136	printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
137out:
138	return result;
139}
140
141static int
142gpio_remove(struct platform_device *dev)
143{
144	device_destroy(gpiodev_class, MKDEV(dev_major, 0));
145	class_destroy(gpiodev_class);
146	unregister_chrdev(dev_major, DEVNAME);
147	return 0;
148}
149
150static struct
151platform_driver gpio_driver = {
152	.probe = gpio_probe,
153	.remove = gpio_remove,
154	.driver = {
155		.name = "GPIODEV",
156		.owner = THIS_MODULE,
157	},
158};
159
160static int __init
161gpio_mod_init(void)
162{
163	int ret = platform_driver_register(&gpio_driver);
164	if (ret)
165		printk(KERN_INFO DRVNAME ": Error registering platfom driver!\n");
166
167	return ret;
168}
169
170static void __exit
171gpio_mod_exit(void)
172{
173	platform_driver_unregister(&gpio_driver);
174}
175
176module_init (gpio_mod_init);
177module_exit (gpio_mod_exit);
178
179MODULE_LICENSE("GPL");
180MODULE_AUTHOR("John Crispin / OpenWrt +");
181MODULE_DESCRIPTION("Character device for for generic gpio api");
182