lcd.c revision 68673afd443c5eeb4cebfb9026e3675f43d79f2b 
1/*
2 * LCD Lowlevel Control Abstraction
3 *
4 * Copyright (C) 2003,2004 Hewlett-Packard Company
5 *
6 */
7
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/device.h>
11#include <linux/lcd.h>
12#include <linux/notifier.h>
13#include <linux/ctype.h>
14#include <linux/err.h>
15#include <linux/fb.h>
16
17static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
18{
19	int rc;
20	struct lcd_device *ld = to_lcd_device(cdev);
21
22	down(&ld->sem);
23	if (likely(ld->props && ld->props->get_power))
24		rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
25	else
26		rc = -ENXIO;
27	up(&ld->sem);
28
29	return rc;
30}
31
32static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
33{
34	int rc = -ENXIO;
35	char *endp;
36	struct lcd_device *ld = to_lcd_device(cdev);
37	int power = simple_strtoul(buf, &endp, 0);
38	size_t size = endp - buf;
39
40	if (*endp && isspace(*endp))
41		size++;
42	if (size != count)
43		return -EINVAL;
44
45	down(&ld->sem);
46	if (likely(ld->props && ld->props->set_power)) {
47		pr_debug("lcd: set power to %d\n", power);
48		ld->props->set_power(ld, power);
49		rc = count;
50	}
51	up(&ld->sem);
52
53	return rc;
54}
55
56static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
57{
58	int rc = -ENXIO;
59	struct lcd_device *ld = to_lcd_device(cdev);
60
61	down(&ld->sem);
62	if (likely(ld->props && ld->props->get_contrast))
63		rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
64	up(&ld->sem);
65
66	return rc;
67}
68
69static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
70{
71	int rc = -ENXIO;
72	char *endp;
73	struct lcd_device *ld = to_lcd_device(cdev);
74	int contrast = simple_strtoul(buf, &endp, 0);
75	size_t size = endp - buf;
76
77	if (*endp && isspace(*endp))
78		size++;
79	if (size != count)
80		return -EINVAL;
81
82	down(&ld->sem);
83	if (likely(ld->props && ld->props->set_contrast)) {
84		pr_debug("lcd: set contrast to %d\n", contrast);
85		ld->props->set_contrast(ld, contrast);
86		rc = count;
87	}
88	up(&ld->sem);
89
90	return rc;
91}
92
93static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
94{
95	int rc = -ENXIO;
96	struct lcd_device *ld = to_lcd_device(cdev);
97
98	down(&ld->sem);
99	if (likely(ld->props))
100		rc = sprintf(buf, "%d\n", ld->props->max_contrast);
101	up(&ld->sem);
102
103	return rc;
104}
105
106static void lcd_class_release(struct class_device *dev)
107{
108	struct lcd_device *ld = to_lcd_device(dev);
109	kfree(ld);
110}
111
112static struct class lcd_class = {
113	.name = "lcd",
114	.release = lcd_class_release,
115};
116
117#define DECLARE_ATTR(_name,_mode,_show,_store)			\
118{							 	\
119	.attr	= { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
120	.show	= _show,					\
121	.store	= _store,					\
122}
123
124static struct class_device_attribute lcd_class_device_attributes[] = {
125	DECLARE_ATTR(power, 0644, lcd_show_power, lcd_store_power),
126	DECLARE_ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
127	DECLARE_ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
128};
129
130/* This callback gets called when something important happens inside a
131 * framebuffer driver. We're looking if that important event is blanking,
132 * and if it is, we're switching lcd power as well ...
133 */
134static int fb_notifier_callback(struct notifier_block *self,
135				 unsigned long event, void *data)
136{
137	struct lcd_device *ld;
138	struct fb_event *evdata =(struct fb_event *)data;
139
140	/* If we aren't interested in this event, skip it immediately ... */
141	if (event != FB_EVENT_BLANK)
142		return 0;
143
144	ld = container_of(self, struct lcd_device, fb_notif);
145	down(&ld->sem);
146	if (ld->props)
147		if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
148			ld->props->set_power(ld, *(int *)evdata->data);
149	up(&ld->sem);
150	return 0;
151}
152
153/**
154 * lcd_device_register - register a new object of lcd_device class.
155 * @name: the name of the new object(must be the same as the name of the
156 *   respective framebuffer device).
157 * @devdata: an optional pointer to be stored in the class_device. The
158 *   methods may retrieve it by using class_get_devdata(ld->class_dev).
159 * @lp: the lcd properties structure.
160 *
161 * Creates and registers a new lcd class_device. Returns either an ERR_PTR()
162 * or a pointer to the newly allocated device.
163 */
164struct lcd_device *lcd_device_register(const char *name, void *devdata,
165				       struct lcd_properties *lp)
166{
167	int i, rc;
168	struct lcd_device *new_ld;
169
170	pr_debug("lcd_device_register: name=%s\n", name);
171
172	new_ld = kmalloc(sizeof(struct lcd_device), GFP_KERNEL);
173	if (unlikely(!new_ld))
174		return ERR_PTR(-ENOMEM);
175
176	init_MUTEX(&new_ld->sem);
177	new_ld->props = lp;
178	memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev));
179	new_ld->class_dev.class = &lcd_class;
180	strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
181	class_set_devdata(&new_ld->class_dev, devdata);
182
183	rc = class_device_register(&new_ld->class_dev);
184	if (unlikely(rc)) {
185error:		kfree(new_ld);
186		return ERR_PTR(rc);
187	}
188
189	memset(&new_ld->fb_notif, 0, sizeof(new_ld->fb_notif));
190	new_ld->fb_notif.notifier_call = fb_notifier_callback;
191
192	rc = fb_register_client(&new_ld->fb_notif);
193	if (unlikely(rc))
194		goto error;
195
196	for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++) {
197		rc = class_device_create_file(&new_ld->class_dev,
198					      &lcd_class_device_attributes[i]);
199		if (unlikely(rc)) {
200			while (--i >= 0)
201				class_device_remove_file(&new_ld->class_dev,
202							 &lcd_class_device_attributes[i]);
203			class_device_unregister(&new_ld->class_dev);
204			/* No need to kfree(new_ld) since release() method was called */
205			return ERR_PTR(rc);
206		}
207	}
208
209	return new_ld;
210}
211EXPORT_SYMBOL(lcd_device_register);
212
213/**
214 * lcd_device_unregister - unregisters a object of lcd_device class.
215 * @ld: the lcd device object to be unregistered and freed.
216 *
217 * Unregisters a previously registered via lcd_device_register object.
218 */
219void lcd_device_unregister(struct lcd_device *ld)
220{
221	int i;
222
223	if (!ld)
224		return;
225
226	pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);
227
228	for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++)
229		class_device_remove_file(&ld->class_dev,
230					 &lcd_class_device_attributes[i]);
231
232	down(&ld->sem);
233	ld->props = NULL;
234	up(&ld->sem);
235
236	fb_unregister_client(&ld->fb_notif);
237
238	class_device_unregister(&ld->class_dev);
239}
240EXPORT_SYMBOL(lcd_device_unregister);
241
242static void __exit lcd_class_exit(void)
243{
244	class_unregister(&lcd_class);
245}
246
247static int __init lcd_class_init(void)
248{
249	return class_register(&lcd_class);
250}
251
252/*
253 * if this is compiled into the kernel, we need to ensure that the
254 * class is registered before users of the class try to register lcd's
255 */
256postcore_initcall(lcd_class_init);
257module_exit(lcd_class_exit);
258
259MODULE_LICENSE("GPL");
260MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
261MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");
262