lcd.c revision 2fd5a15489dd2e58009ffd4ecbadb36a40f67d2b 
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
17#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
18			   defined(CONFIG_LCD_CLASS_DEVICE_MODULE))
19/* This callback gets called when something important happens inside a
20 * framebuffer driver. We're looking if that important event is blanking,
21 * and if it is, we're switching lcd power as well ...
22 */
23static int fb_notifier_callback(struct notifier_block *self,
24				 unsigned long event, void *data)
25{
26	struct lcd_device *ld;
27	struct fb_event *evdata = data;
28
29	/* If we aren't interested in this event, skip it immediately ... */
30	if (event != FB_EVENT_BLANK)
31		return 0;
32
33	ld = container_of(self, struct lcd_device, fb_notif);
34	down(&ld->sem);
35	if (ld->props)
36		if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
37			ld->props->set_power(ld, *(int *)evdata->data);
38	up(&ld->sem);
39	return 0;
40}
41
42static int lcd_register_fb(struct lcd_device *ld)
43{
44	memset(&ld->fb_notif, 0, sizeof(&ld->fb_notif));
45	ld->fb_notif.notifier_call = fb_notifier_callback;
46	return fb_register_client(&ld->fb_notif);
47}
48
49static void lcd_unregister_fb(struct lcd_device *ld)
50{
51	fb_unregister_client(&ld->fb_notif);
52}
53#else
54static int lcd_register_fb(struct lcd_device *ld)
55{
56	return 0;
57}
58
59static inline void lcd_unregister_fb(struct lcd_device *ld)
60{
61}
62#endif /* CONFIG_FB */
63
64static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
65{
66	int rc;
67	struct lcd_device *ld = to_lcd_device(cdev);
68
69	down(&ld->sem);
70	if (likely(ld->props && ld->props->get_power))
71		rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
72	else
73		rc = -ENXIO;
74	up(&ld->sem);
75
76	return rc;
77}
78
79static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
80{
81	int rc = -ENXIO;
82	char *endp;
83	struct lcd_device *ld = to_lcd_device(cdev);
84	int power = simple_strtoul(buf, &endp, 0);
85	size_t size = endp - buf;
86
87	if (*endp && isspace(*endp))
88		size++;
89	if (size != count)
90		return -EINVAL;
91
92	down(&ld->sem);
93	if (likely(ld->props && ld->props->set_power)) {
94		pr_debug("lcd: set power to %d\n", power);
95		ld->props->set_power(ld, power);
96		rc = count;
97	}
98	up(&ld->sem);
99
100	return rc;
101}
102
103static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
104{
105	int rc = -ENXIO;
106	struct lcd_device *ld = to_lcd_device(cdev);
107
108	down(&ld->sem);
109	if (likely(ld->props && ld->props->get_contrast))
110		rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
111	up(&ld->sem);
112
113	return rc;
114}
115
116static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
117{
118	int rc = -ENXIO;
119	char *endp;
120	struct lcd_device *ld = to_lcd_device(cdev);
121	int contrast = simple_strtoul(buf, &endp, 0);
122	size_t size = endp - buf;
123
124	if (*endp && isspace(*endp))
125		size++;
126	if (size != count)
127		return -EINVAL;
128
129	down(&ld->sem);
130	if (likely(ld->props && ld->props->set_contrast)) {
131		pr_debug("lcd: set contrast to %d\n", contrast);
132		ld->props->set_contrast(ld, contrast);
133		rc = count;
134	}
135	up(&ld->sem);
136
137	return rc;
138}
139
140static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
141{
142	int rc = -ENXIO;
143	struct lcd_device *ld = to_lcd_device(cdev);
144
145	down(&ld->sem);
146	if (likely(ld->props))
147		rc = sprintf(buf, "%d\n", ld->props->max_contrast);
148	up(&ld->sem);
149
150	return rc;
151}
152
153static void lcd_class_release(struct class_device *dev)
154{
155	struct lcd_device *ld = to_lcd_device(dev);
156	kfree(ld);
157}
158
159static struct class lcd_class = {
160	.name = "lcd",
161	.release = lcd_class_release,
162};
163
164#define DECLARE_ATTR(_name,_mode,_show,_store)			\
165{							 	\
166	.attr	= { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
167	.show	= _show,					\
168	.store	= _store,					\
169}
170
171static const struct class_device_attribute lcd_class_device_attributes[] = {
172	DECLARE_ATTR(power, 0644, lcd_show_power, lcd_store_power),
173	DECLARE_ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
174	DECLARE_ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
175};
176
177/**
178 * lcd_device_register - register a new object of lcd_device class.
179 * @name: the name of the new object(must be the same as the name of the
180 *   respective framebuffer device).
181 * @devdata: an optional pointer to be stored in the class_device. The
182 *   methods may retrieve it by using class_get_devdata(ld->class_dev).
183 * @lp: the lcd properties structure.
184 *
185 * Creates and registers a new lcd class_device. Returns either an ERR_PTR()
186 * or a pointer to the newly allocated device.
187 */
188struct lcd_device *lcd_device_register(const char *name, void *devdata,
189				       struct lcd_properties *lp)
190{
191	int i, rc;
192	struct lcd_device *new_ld;
193
194	pr_debug("lcd_device_register: name=%s\n", name);
195
196	new_ld = kmalloc(sizeof(struct lcd_device), GFP_KERNEL);
197	if (unlikely(!new_ld))
198		return ERR_PTR(-ENOMEM);
199
200	init_MUTEX(&new_ld->sem);
201	new_ld->props = lp;
202	memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev));
203	new_ld->class_dev.class = &lcd_class;
204	strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
205	class_set_devdata(&new_ld->class_dev, devdata);
206
207	rc = class_device_register(&new_ld->class_dev);
208	if (unlikely(rc)) {
209		kfree(new_ld);
210		return ERR_PTR(rc);
211	}
212
213	rc = lcd_register_fb(new_ld);
214	if (rc) {
215		class_device_unregister(&new_ld->class_dev);
216		return ERR_PTR(rc);
217	}
218
219	for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++) {
220		rc = class_device_create_file(&new_ld->class_dev,
221					      &lcd_class_device_attributes[i]);
222		if (unlikely(rc)) {
223			while (--i >= 0)
224				class_device_remove_file(&new_ld->class_dev,
225							 &lcd_class_device_attributes[i]);
226			class_device_unregister(&new_ld->class_dev);
227			/* No need to kfree(new_ld) since release() method was called */
228			return ERR_PTR(rc);
229		}
230	}
231
232	return new_ld;
233}
234EXPORT_SYMBOL(lcd_device_register);
235
236/**
237 * lcd_device_unregister - unregisters a object of lcd_device class.
238 * @ld: the lcd device object to be unregistered and freed.
239 *
240 * Unregisters a previously registered via lcd_device_register object.
241 */
242void lcd_device_unregister(struct lcd_device *ld)
243{
244	int i;
245
246	if (!ld)
247		return;
248
249	pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);
250
251	for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++)
252		class_device_remove_file(&ld->class_dev,
253					 &lcd_class_device_attributes[i]);
254
255	down(&ld->sem);
256	ld->props = NULL;
257	up(&ld->sem);
258	lcd_unregister_fb(ld);
259	class_device_unregister(&ld->class_dev);
260}
261EXPORT_SYMBOL(lcd_device_unregister);
262
263static void __exit lcd_class_exit(void)
264{
265	class_unregister(&lcd_class);
266}
267
268static int __init lcd_class_init(void)
269{
270	return class_register(&lcd_class);
271}
272
273/*
274 * if this is compiled into the kernel, we need to ensure that the
275 * class is registered before users of the class try to register lcd's
276 */
277postcore_initcall(lcd_class_init);
278module_exit(lcd_class_exit);
279
280MODULE_LICENSE("GPL");
281MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
282MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");
283