1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
/*
* character device wrapper for generic gpio layer
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
*
* Feedback, Bugs... blogic@openwrt.org
*
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/gpio.h>
#include <asm/atomic.h>
#include <linux/init.h>
#include <linux/genhd.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/gpio_dev.h>
#define DRVNAME "gpiodev"
#define DEVNAME "gpio"
static int dev_major;
static unsigned int gpio_access_mask;
static struct class *gpiodev_class;
/* Counter is 1, if the device is not opened and zero (or less) if opened. */
static atomic_t gpio_open_cnt = ATOMIC_INIT(1);
static int
gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg)
{
int retval = 0;
if (((1 << arg) & gpio_access_mask) != (1 << arg))
{
retval = -EINVAL;
goto out;
}
switch (cmd)
{
case GPIO_GET:
retval = gpio_get_value(arg);
break;
case GPIO_SET:
gpio_set_value(arg, 1);
break;
case GPIO_CLEAR:
gpio_set_value(arg, 0);
break;
case GPIO_DIR_IN:
gpio_direction_input(arg);
break;
case GPIO_DIR_OUT:
gpio_direction_output(arg, 0);
break;
default:
retval = -EINVAL;
break;
}
out:
return retval;
}
static int
gpio_open(struct inode *inode, struct file *file)
{
int result = 0;
unsigned int dev_minor = MINOR(inode->i_rdev);
if (dev_minor != 0)
{
printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
result = -ENODEV;
goto out;
}
/* FIXME: We should really allow multiple applications to open the device
* at the same time, as long as the apps access different IO pins.
* The generic gpio-registration functions can be used for that.
* Two new IOCTLs have to be introduced for that. Need to check userspace
* compatibility first. --mb */
if (!atomic_dec_and_test(&gpio_open_cnt)) {
atomic_inc(&gpio_open_cnt);
printk(KERN_ERR DRVNAME ": Device with minor ID %d already in use\n", dev_minor);
result = -EBUSY;
goto out;
}
out:
return result;
}
static int
gpio_close(struct inode * inode, struct file * file)
{
smp_mb__before_atomic_inc();
atomic_inc(&gpio_open_cnt);
return 0;
}
struct file_operations gpio_fops = {
ioctl: gpio_ioctl,
open: gpio_open,
release: gpio_close
};
static int
gpio_probe(struct platform_device *dev)
{
int result = 0;
dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
if (!dev_major)
{
printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
result = -ENODEV;
goto out;
}
gpiodev_class = class_create(THIS_MODULE, DRVNAME);
class_device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), NULL, DEVNAME);
printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
if (dev->num_resources != 1)
{
printk(KERN_ERR DRVNAME ": device may only have 1 resource\n");
result = -ENODEV;
goto out;
}
gpio_access_mask = dev->resource[0].start;
printk(KERN_INFO DRVNAME ": gpio platform device registered with access mask %08X\n", gpio_access_mask);
out:
return result;
}
static int
gpio_remove(struct platform_device *dev)
{
unregister_chrdev(dev_major, DEVNAME);
return 0;
}
static struct
platform_driver gpio_driver = {
.probe = gpio_probe,
.remove = gpio_remove,
.driver = {
.name = "GPIODEV",
.owner = THIS_MODULE,
},
};
static int __init
gpio_mod_init(void)
{
int ret = platform_driver_register(&gpio_driver);
if (ret)
printk(KERN_INFO DRVNAME ": Error registering platfom driver!");
return ret;
}
static void __exit
gpio_mod_exit(void)
{
platform_driver_unregister(&gpio_driver);
}
module_init (gpio_mod_init);
module_exit (gpio_mod_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Crispin / OpenWrt");
MODULE_DESCRIPTION("Character device for for generic gpio api");
|
