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  */
fb_notifier_callback(struct notifier_block * self,unsigned long event,void * data)24 static 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 
lcd_register_fb(struct lcd_device * ld)58 static 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 
lcd_unregister_fb(struct lcd_device * ld)65 static void lcd_unregister_fb(struct lcd_device *ld)
66 {
67 	fb_unregister_client(&ld->fb_notif);
68 }
69 #else
lcd_register_fb(struct lcd_device * ld)70 static int lcd_register_fb(struct lcd_device *ld)
71 {
72 	return 0;
73 }
74 
lcd_unregister_fb(struct lcd_device * ld)75 static inline void lcd_unregister_fb(struct lcd_device *ld)
76 {
77 }
78 #endif /* CONFIG_FB */
79 
lcd_show_power(struct device * dev,struct device_attribute * attr,char * buf)80 static 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 
lcd_store_power(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)96 static 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 	struct lcd_device *ld = to_lcd_device(dev);
101 	unsigned long power;
102 
103 	rc = kstrtoul(buf, 0, &power);
104 	if (rc)
105 		return rc;
106 
107 	mutex_lock(&ld->ops_lock);
108 	if (ld->ops && ld->ops->set_power) {
109 		pr_debug("lcd: set power to %lu\n", power);
110 		ld->ops->set_power(ld, power);
111 		rc = count;
112 	}
113 	mutex_unlock(&ld->ops_lock);
114 
115 	return rc;
116 }
117 
lcd_show_contrast(struct device * dev,struct device_attribute * attr,char * buf)118 static ssize_t lcd_show_contrast(struct device *dev,
119 		struct device_attribute *attr, char *buf)
120 {
121 	int rc = -ENXIO;
122 	struct lcd_device *ld = to_lcd_device(dev);
123 
124 	mutex_lock(&ld->ops_lock);
125 	if (ld->ops && ld->ops->get_contrast)
126 		rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
127 	mutex_unlock(&ld->ops_lock);
128 
129 	return rc;
130 }
131 
lcd_store_contrast(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)132 static ssize_t lcd_store_contrast(struct device *dev,
133 		struct device_attribute *attr, const char *buf, size_t count)
134 {
135 	int rc = -ENXIO;
136 	struct lcd_device *ld = to_lcd_device(dev);
137 	unsigned long contrast;
138 
139 	rc = kstrtoul(buf, 0, &contrast);
140 	if (rc)
141 		return rc;
142 
143 	mutex_lock(&ld->ops_lock);
144 	if (ld->ops && ld->ops->set_contrast) {
145 		pr_debug("lcd: set contrast to %lu\n", contrast);
146 		ld->ops->set_contrast(ld, contrast);
147 		rc = count;
148 	}
149 	mutex_unlock(&ld->ops_lock);
150 
151 	return rc;
152 }
153 
lcd_show_max_contrast(struct device * dev,struct device_attribute * attr,char * buf)154 static ssize_t lcd_show_max_contrast(struct device *dev,
155 		struct device_attribute *attr, char *buf)
156 {
157 	struct lcd_device *ld = to_lcd_device(dev);
158 
159 	return sprintf(buf, "%d\n", ld->props.max_contrast);
160 }
161 
162 static struct class *lcd_class;
163 
lcd_device_release(struct device * dev)164 static void lcd_device_release(struct device *dev)
165 {
166 	struct lcd_device *ld = to_lcd_device(dev);
167 	kfree(ld);
168 }
169 
170 static struct device_attribute lcd_device_attributes[] = {
171 	__ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
172 	__ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
173 	__ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
174 	__ATTR_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 device. The
182  *   methods may retrieve it by using lcd_get_data(ld).
183  * @ops: the lcd operations structure.
184  *
185  * Creates and registers a new lcd device. Returns either an ERR_PTR()
186  * or a pointer to the newly allocated device.
187  */
lcd_device_register(const char * name,struct device * parent,void * devdata,struct lcd_ops * ops)188 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
189 		void *devdata, struct lcd_ops *ops)
190 {
191 	struct lcd_device *new_ld;
192 	int rc;
193 
194 	pr_debug("lcd_device_register: name=%s\n", name);
195 
196 	new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
197 	if (!new_ld)
198 		return ERR_PTR(-ENOMEM);
199 
200 	mutex_init(&new_ld->ops_lock);
201 	mutex_init(&new_ld->update_lock);
202 
203 	new_ld->dev.class = lcd_class;
204 	new_ld->dev.parent = parent;
205 	new_ld->dev.release = lcd_device_release;
206 	dev_set_name(&new_ld->dev, name);
207 	dev_set_drvdata(&new_ld->dev, devdata);
208 
209 	rc = device_register(&new_ld->dev);
210 	if (rc) {
211 		kfree(new_ld);
212 		return ERR_PTR(rc);
213 	}
214 
215 	rc = lcd_register_fb(new_ld);
216 	if (rc) {
217 		device_unregister(&new_ld->dev);
218 		return ERR_PTR(rc);
219 	}
220 
221 	new_ld->ops = ops;
222 
223 	return new_ld;
224 }
225 EXPORT_SYMBOL(lcd_device_register);
226 
227 /**
228  * lcd_device_unregister - unregisters a object of lcd_device class.
229  * @ld: the lcd device object to be unregistered and freed.
230  *
231  * Unregisters a previously registered via lcd_device_register object.
232  */
lcd_device_unregister(struct lcd_device * ld)233 void lcd_device_unregister(struct lcd_device *ld)
234 {
235 	if (!ld)
236 		return;
237 
238 	mutex_lock(&ld->ops_lock);
239 	ld->ops = NULL;
240 	mutex_unlock(&ld->ops_lock);
241 	lcd_unregister_fb(ld);
242 
243 	device_unregister(&ld->dev);
244 }
245 EXPORT_SYMBOL(lcd_device_unregister);
246 
lcd_class_exit(void)247 static void __exit lcd_class_exit(void)
248 {
249 	class_destroy(lcd_class);
250 }
251 
lcd_class_init(void)252 static int __init lcd_class_init(void)
253 {
254 	lcd_class = class_create(THIS_MODULE, "lcd");
255 	if (IS_ERR(lcd_class)) {
256 		printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
257 				PTR_ERR(lcd_class));
258 		return PTR_ERR(lcd_class);
259 	}
260 
261 	lcd_class->dev_attrs = lcd_device_attributes;
262 	return 0;
263 }
264 
265 /*
266  * if this is compiled into the kernel, we need to ensure that the
267  * class is registered before users of the class try to register lcd's
268  */
269 postcore_initcall(lcd_class_init);
270 module_exit(lcd_class_exit);
271 
272 MODULE_LICENSE("GPL");
273 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
274 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");
275