2 * Backlight Lowlevel Control Abstraction
4 * Copyright (C) 2003,2004 Hewlett-Packard Company
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/device.h>
11 #include <linux/backlight.h>
12 #include <linux/notifier.h>
13 #include <linux/ctype.h>
14 #include <linux/err.h>
18 static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
21 struct backlight_device *bd = to_backlight_device(cdev);
24 if (likely(bd->props && bd->props->get_power))
25 rc = sprintf(buf, "%d\n", bd->props->get_power(bd));
33 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
37 struct backlight_device *bd = to_backlight_device(cdev);
39 power = simple_strtoul(buf, &endp, 0);
40 if (*endp && !isspace(*endp))
44 if (likely(bd->props && bd->props->set_power)) {
45 pr_debug("backlight: set power to %d\n", power);
46 bd->props->set_power(bd, power);
55 static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
58 struct backlight_device *bd = to_backlight_device(cdev);
61 if (likely(bd->props && bd->props->get_brightness))
62 rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd));
70 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
74 struct backlight_device *bd = to_backlight_device(cdev);
76 brightness = simple_strtoul(buf, &endp, 0);
77 if (*endp && !isspace(*endp))
81 if (likely(bd->props && bd->props->set_brightness)) {
82 pr_debug("backlight: set brightness to %d\n", brightness);
83 bd->props->set_brightness(bd, brightness);
92 static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
95 struct backlight_device *bd = to_backlight_device(cdev);
98 if (likely(bd->props))
99 rc = sprintf(buf, "%d\n", bd->props->max_brightness);
107 static void backlight_class_release(struct class_device *dev)
109 struct backlight_device *bd = to_backlight_device(dev);
113 static struct class backlight_class = {
115 .release = backlight_class_release,
118 #define DECLARE_ATTR(_name,_mode,_show,_store) \
120 .attr = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE }, \
125 static struct class_device_attribute bl_class_device_attributes[] = {
126 DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
127 DECLARE_ATTR(brightness, 0644, backlight_show_brightness, backlight_store_brightness),
128 DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
131 /* This callback gets called when something important happens inside a
132 * framebuffer driver. We're looking if that important event is blanking,
133 * and if it is, we're switching backlight power as well ...
135 static int fb_notifier_callback(struct notifier_block *self,
136 unsigned long event, void *data)
138 struct backlight_device *bd;
139 struct fb_event *evdata =(struct fb_event *)data;
141 /* If we aren't interested in this event, skip it immediately ... */
142 if (event != FB_EVENT_BLANK)
145 bd = container_of(self, struct backlight_device, fb_notif);
148 if (!bd->props->check_fb || bd->props->check_fb(evdata->info))
149 bd->props->set_power(bd, *(int *)evdata->data);
155 * backlight_device_register - create and register a new object of
156 * backlight_device class.
157 * @name: the name of the new object(must be the same as the name of the
158 * respective framebuffer device).
159 * @devdata: an optional pointer to be stored in the class_device. The
160 * methods may retrieve it by using class_get_devdata(&bd->class_dev).
161 * @bp: the backlight properties structure.
163 * Creates and registers new backlight class_device. Returns either an
164 * ERR_PTR() or a pointer to the newly allocated device.
166 struct backlight_device *backlight_device_register(const char *name, void *devdata,
167 struct backlight_properties *bp)
170 struct backlight_device *new_bd;
172 pr_debug("backlight_device_alloc: name=%s\n", name);
174 new_bd = kmalloc(sizeof(struct backlight_device), GFP_KERNEL);
175 if (unlikely(!new_bd))
176 return ERR_PTR(ENOMEM);
178 init_MUTEX(&new_bd->sem);
180 memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev));
181 new_bd->class_dev.class = &backlight_class;
182 strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
183 class_set_devdata(&new_bd->class_dev, devdata);
185 rc = class_device_register(&new_bd->class_dev);
187 error: kfree(new_bd);
191 memset(&new_bd->fb_notif, 0, sizeof(new_bd->fb_notif));
192 new_bd->fb_notif.notifier_call = fb_notifier_callback;
194 rc = fb_register_client(&new_bd->fb_notif);
198 for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
199 rc = class_device_create_file(&new_bd->class_dev,
200 &bl_class_device_attributes[i]);
203 class_device_remove_file(&new_bd->class_dev,
204 &bl_class_device_attributes[i]);
205 class_device_unregister(&new_bd->class_dev);
206 /* No need to kfree(new_bd) since release() method was called */
213 EXPORT_SYMBOL(backlight_device_register);
216 * backlight_device_unregister - unregisters a backlight device object.
217 * @bd: the backlight device object to be unregistered and freed.
219 * Unregisters a previously registered via backlight_device_register object.
221 void backlight_device_unregister(struct backlight_device *bd)
228 pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);
230 for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
231 class_device_remove_file(&bd->class_dev,
232 &bl_class_device_attributes[i]);
238 fb_unregister_client(&bd->fb_notif);
240 class_device_unregister(&bd->class_dev);
242 EXPORT_SYMBOL(backlight_device_unregister);
244 static void __exit backlight_class_exit(void)
246 class_unregister(&backlight_class);
249 static int __init backlight_class_init(void)
251 return class_register(&backlight_class);
255 * if this is compiled into the kernel, we need to ensure that the
256 * class is registered before users of the class try to register lcd's
258 postcore_initcall(backlight_class_init);
259 module_exit(backlight_class_exit);
261 MODULE_LICENSE("GPL");
262 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
263 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");