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18#include <linux/fs.h>
19#include <linux/init.h>
20#include <linux/leds.h>
21#include <linux/miscdevice.h>
22#include <linux/module.h>
23#include <linux/poll.h>
24#include <linux/sched.h>
25#include <linux/slab.h>
26
27#include <uapi/linux/uleds.h>
28
29#define ULEDS_NAME "uleds"
30
31enum uleds_state {
32 ULEDS_STATE_UNKNOWN,
33 ULEDS_STATE_REGISTERED,
34};
35
36struct uleds_device {
37 struct uleds_user_dev user_dev;
38 struct led_classdev led_cdev;
39 struct mutex mutex;
40 enum uleds_state state;
41 wait_queue_head_t waitq;
42 int brightness;
43 bool new_data;
44};
45
46static struct miscdevice uleds_misc;
47
48static void uleds_brightness_set(struct led_classdev *led_cdev,
49 enum led_brightness brightness)
50{
51 struct uleds_device *udev = container_of(led_cdev, struct uleds_device,
52 led_cdev);
53
54 if (udev->brightness != brightness) {
55 udev->brightness = brightness;
56 udev->new_data = true;
57 wake_up_interruptible(&udev->waitq);
58 }
59}
60
61static int uleds_open(struct inode *inode, struct file *file)
62{
63 struct uleds_device *udev;
64
65 udev = kzalloc(sizeof(*udev), GFP_KERNEL);
66 if (!udev)
67 return -ENOMEM;
68
69 udev->led_cdev.name = udev->user_dev.name;
70 udev->led_cdev.brightness_set = uleds_brightness_set;
71
72 mutex_init(&udev->mutex);
73 init_waitqueue_head(&udev->waitq);
74 udev->state = ULEDS_STATE_UNKNOWN;
75
76 file->private_data = udev;
77 nonseekable_open(inode, file);
78
79 return 0;
80}
81
82static ssize_t uleds_write(struct file *file, const char __user *buffer,
83 size_t count, loff_t *ppos)
84{
85 struct uleds_device *udev = file->private_data;
86 const char *name;
87 int ret;
88
89 if (count == 0)
90 return 0;
91
92 ret = mutex_lock_interruptible(&udev->mutex);
93 if (ret)
94 return ret;
95
96 if (udev->state == ULEDS_STATE_REGISTERED) {
97 ret = -EBUSY;
98 goto out;
99 }
100
101 if (count != sizeof(struct uleds_user_dev)) {
102 ret = -EINVAL;
103 goto out;
104 }
105
106 if (copy_from_user(&udev->user_dev, buffer,
107 sizeof(struct uleds_user_dev))) {
108 ret = -EFAULT;
109 goto out;
110 }
111
112 name = udev->user_dev.name;
113 if (!name[0] || !strcmp(name, ".") || !strcmp(name, "..") ||
114 strchr(name, '/')) {
115 ret = -EINVAL;
116 goto out;
117 }
118
119 if (udev->user_dev.max_brightness <= 0) {
120 ret = -EINVAL;
121 goto out;
122 }
123 udev->led_cdev.max_brightness = udev->user_dev.max_brightness;
124
125 ret = devm_led_classdev_register(uleds_misc.this_device,
126 &udev->led_cdev);
127 if (ret < 0)
128 goto out;
129
130 udev->new_data = true;
131 udev->state = ULEDS_STATE_REGISTERED;
132 ret = count;
133
134out:
135 mutex_unlock(&udev->mutex);
136
137 return ret;
138}
139
140static ssize_t uleds_read(struct file *file, char __user *buffer, size_t count,
141 loff_t *ppos)
142{
143 struct uleds_device *udev = file->private_data;
144 ssize_t retval;
145
146 if (count < sizeof(udev->brightness))
147 return 0;
148
149 do {
150 retval = mutex_lock_interruptible(&udev->mutex);
151 if (retval)
152 return retval;
153
154 if (udev->state != ULEDS_STATE_REGISTERED) {
155 retval = -ENODEV;
156 } else if (!udev->new_data && (file->f_flags & O_NONBLOCK)) {
157 retval = -EAGAIN;
158 } else if (udev->new_data) {
159 retval = copy_to_user(buffer, &udev->brightness,
160 sizeof(udev->brightness));
161 udev->new_data = false;
162 retval = sizeof(udev->brightness);
163 }
164
165 mutex_unlock(&udev->mutex);
166
167 if (retval)
168 break;
169
170 if (!(file->f_flags & O_NONBLOCK))
171 retval = wait_event_interruptible(udev->waitq,
172 udev->new_data ||
173 udev->state != ULEDS_STATE_REGISTERED);
174 } while (retval == 0);
175
176 return retval;
177}
178
179static unsigned int uleds_poll(struct file *file, poll_table *wait)
180{
181 struct uleds_device *udev = file->private_data;
182
183 poll_wait(file, &udev->waitq, wait);
184
185 if (udev->new_data)
186 return POLLIN | POLLRDNORM;
187
188 return 0;
189}
190
191static int uleds_release(struct inode *inode, struct file *file)
192{
193 struct uleds_device *udev = file->private_data;
194
195 if (udev->state == ULEDS_STATE_REGISTERED) {
196 udev->state = ULEDS_STATE_UNKNOWN;
197 devm_led_classdev_unregister(uleds_misc.this_device,
198 &udev->led_cdev);
199 }
200 kfree(udev);
201
202 return 0;
203}
204
205static const struct file_operations uleds_fops = {
206 .owner = THIS_MODULE,
207 .open = uleds_open,
208 .release = uleds_release,
209 .read = uleds_read,
210 .write = uleds_write,
211 .poll = uleds_poll,
212 .llseek = no_llseek,
213};
214
215static struct miscdevice uleds_misc = {
216 .fops = &uleds_fops,
217 .minor = MISC_DYNAMIC_MINOR,
218 .name = ULEDS_NAME,
219};
220
221static int __init uleds_init(void)
222{
223 return misc_register(&uleds_misc);
224}
225module_init(uleds_init);
226
227static void __exit uleds_exit(void)
228{
229 misc_deregister(&uleds_misc);
230}
231module_exit(uleds_exit);
232
233MODULE_AUTHOR("David Lechner <david@lechnology.com>");
234MODULE_DESCRIPTION("Userspace driver for the LED subsystem");
235MODULE_LICENSE("GPL");
236
