/drivers/video/backlight/lcd.c

  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#include <linux/slab.h>
 17
 18#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
 19			   defined(CONFIG_LCD_CLASS_DEVICE_MODULE))
 20/* This callback gets called when something important happens inside a
 21 * framebuffer driver. We're looking if that important event is blanking,
 22 * and if it is, we're switching lcd power as well ...
 23 */
 24static int fb_notifier_callback(struct notifier_block *self,
 25				 unsigned long event, void *data)
 26{
 27	struct lcd_device *ld;
 28	struct fb_event *evdata = data;
 29
 30	/* If we aren't interested in this event, skip it immediately ... */
 31	switch (event) {
 32	case FB_EVENT_BLANK:
 33	case FB_EVENT_MODE_CHANGE:
 34	case FB_EVENT_MODE_CHANGE_ALL:
 35		break;
 36	default:
 37		return 0;
 38	}
 39
 40	ld = container_of(self, struct lcd_device, fb_notif);
 41	if (!ld->ops)
 42		return 0;
 43
 44	mutex_lock(&ld->ops_lock);
 45	if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
 46		if (event == FB_EVENT_BLANK) {
 47			if (ld->ops->set_power)
 48				ld->ops->set_power(ld, *(int *)evdata->data);
 49		} else {
 50			if (ld->ops->set_mode)
 51				ld->ops->set_mode(ld, evdata->data);
 52		}
 53	}
 54	mutex_unlock(&ld->ops_lock);
 55	return 0;
 56}
 57
 58static int lcd_register_fb(struct lcd_device *ld)
 59{
 60	memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
 61	ld->fb_notif.notifier_call = fb_notifier_callback;
 62	return fb_register_client(&ld->fb_notif);
 63}
 64
 65static void lcd_unregister_fb(struct lcd_device *ld)
 66{
 67	fb_unregister_client(&ld->fb_notif);
 68}
 69#else
 70static int lcd_register_fb(struct lcd_device *ld)
 71{
 72	return 0;
 73}
 74
 75static inline void lcd_unregister_fb(struct lcd_device *ld)
 76{
 77}
 78#endif /* CONFIG_FB */
 79
 80static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
 81		char *buf)
 82{
 83	int rc;
 84	struct lcd_device *ld = to_lcd_device(dev);
 85
 86	mutex_lock(&ld->ops_lock);
 87	if (ld->ops && ld->ops->get_power)
 88		rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
 89	else
 90		rc = -ENXIO;
 91	mutex_unlock(&ld->ops_lock);
 92
 93	return rc;
 94}
 95
 96static ssize_t lcd_store_power(struct device *dev,
 97		struct device_attribute *attr, const char *buf, size_t count)
 98{
 99	int rc = -ENXIO;
100	char *endp;
101	struct lcd_device *ld = to_lcd_device(dev);
102	int power = simple_strtoul(buf, &endp, 0);
103	size_t size = endp - buf;
104
105	if (isspace(*endp))
106		size++;
107	if (size != count)
108		return -EINVAL;
109
110	mutex_lock(&ld->ops_lock);
111	if (ld->ops && ld->ops->set_power) {
112		pr_debug("lcd: set power to %d\n", power);
113		ld->ops->set_power(ld, power);
114		rc = count;
115	}
116	mutex_unlock(&ld->ops_lock);
117
118	return rc;
119}
120
121static ssize_t lcd_show_contrast(struct device *dev,
122		struct device_attribute *attr, char *buf)
123{
124	int rc = -ENXIO;
125	struct lcd_device *ld = to_lcd_device(dev);
126
127	mutex_lock(&ld->ops_lock);
128	if (ld->ops && ld->ops->get_contrast)
129		rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
130	mutex_unlock(&ld->ops_lock);
131
132	return rc;
133}
134
135static ssize_t lcd_store_contrast(struct device *dev,
136		struct device_attribute *attr, const char *buf, size_t count)
137{
138	int rc = -ENXIO;
139	char *endp;
140	struct lcd_device *ld = to_lcd_device(dev);
141	int contrast = simple_strtoul(buf, &endp, 0);
142	size_t size = endp - buf;
143
144	if (isspace(*endp))
145		size++;
146	if (size != count)
147		return -EINVAL;
148
149	mutex_lock(&ld->ops_lock);
150	if (ld->ops && ld->ops->set_contrast) {
151		pr_debug("lcd: set contrast to %d\n", contrast);
152		ld->ops->set_contrast(ld, contrast);
153		rc = count;
154	}
155	mutex_unlock(&ld->ops_lock);
156
157	return rc;
158}
159
160static ssize_t lcd_show_max_contrast(struct device *dev,
161		struct device_attribute *attr, char *buf)
162{
163	struct lcd_device *ld = to_lcd_device(dev);
164
165	return sprintf(buf, "%d\n", ld->props.max_contrast);
166}
167
168static struct class *lcd_class;
169
170static void lcd_device_release(struct device *dev)
171{
172	struct lcd_device *ld = to_lcd_device(dev);
173	kfree(ld);
174}
175
176static struct device_attribute lcd_device_attributes[] = {
177	__ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
178	__ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
179	__ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
180	__ATTR_NULL,
181};
182
183/**
184 * lcd_device_register - register a new object of lcd_device class.
185 * @name: the name of the new object(must be the same as the name of the
186 *   respective framebuffer device).
187 * @devdata: an optional pointer to be stored in the device. The
188 *   methods may retrieve it by using lcd_get_data(ld).
189 * @ops: the lcd operations structure.
190 *
191 * Creates and registers a new lcd device. Returns either an ERR_PTR()
192 * or a pointer to the newly allocated device.
193 */
194struct lcd_device *lcd_device_register(const char *name, struct device *parent,
195		void *devdata, struct lcd_ops *ops)
196{
197	struct lcd_device *new_ld;
198	int rc;
199
200	pr_debug("lcd_device_register: name=%s\n", name);
201
202	new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
203	if (!new_ld)
204		return ERR_PTR(-ENOMEM);
205
206	mutex_init(&new_ld->ops_lock);
207	mutex_init(&new_ld->update_lock);
208
209	new_ld->dev.class = lcd_class;
210	new_ld->dev.parent = parent;
211	new_ld->dev.release = lcd_device_release;
212	dev_set_name(&new_ld->dev, name);
213	dev_set_drvdata(&new_ld->dev, devdata);
214
215	rc = device_register(&new_ld->dev);
216	if (rc) {
217		kfree(new_ld);
218		return ERR_PTR(rc);
219	}
220
221	rc = lcd_register_fb(new_ld);
222	if (rc) {
223		device_unregister(&new_ld->dev);
224		return ERR_PTR(rc);
225	}
226
227	new_ld->ops = ops;
228
229	return new_ld;
230}
231EXPORT_SYMBOL(lcd_device_register);
232
233/**
234 * lcd_device_unregister - unregisters a object of lcd_device class.
235 * @ld: the lcd device object to be unregistered and freed.
236 *
237 * Unregisters a previously registered via lcd_device_register object.
238 */
239void lcd_device_unregister(struct lcd_device *ld)
240{
241	if (!ld)
242		return;
243
244	mutex_lock(&ld->ops_lock);
245	ld->ops = NULL;
246	mutex_unlock(&ld->ops_lock);
247	lcd_unregister_fb(ld);
248
249	device_unregister(&ld->dev);
250}
251EXPORT_SYMBOL(lcd_device_unregister);
252
253static void __exit lcd_class_exit(void)
254{
255	class_destroy(lcd_class);
256}
257
258static int __init lcd_class_init(void)
259{
260	lcd_class = class_create(THIS_MODULE, "lcd");
261	if (IS_ERR(lcd_class)) {
262		printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
263				PTR_ERR(lcd_class));
264		return PTR_ERR(lcd_class);
265	}
266
267	lcd_class->dev_attrs = lcd_device_attributes;
268	return 0;
269}
270
271/*
272 * if this is compiled into the kernel, we need to ensure that the
273 * class is registered before users of the class try to register lcd's
274 */
275postcore_initcall(lcd_class_init);
276module_exit(lcd_class_exit);
277
278MODULE_LICENSE("GPL");
279MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
280MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");