1 // SPDX-License-Identifier: GPL-2.0-only
3 * LCD Lowlevel Control Abstraction
5 * Copyright (C) 2003,2004 Hewlett-Packard Company
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/device.h>
14 #include <linux/lcd.h>
15 #include <linux/notifier.h>
16 #include <linux/ctype.h>
17 #include <linux/err.h>
19 #include <linux/slab.h>
21 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
22 defined(CONFIG_LCD_CLASS_DEVICE_MODULE))
23 /* This callback gets called when something important happens inside a
24 * framebuffer driver. We're looking if that important event is blanking,
25 * and if it is, we're switching lcd power as well ...
27 static int fb_notifier_callback(struct notifier_block *self,
28 unsigned long event, void *data)
30 struct lcd_device *ld;
31 struct fb_event *evdata = data;
33 ld = container_of(self, struct lcd_device, fb_notif);
37 mutex_lock(&ld->ops_lock);
38 if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
39 if (event == FB_EVENT_BLANK) {
40 if (ld->ops->set_power)
41 ld->ops->set_power(ld, *(int *)evdata->data);
42 } else if (event == FB_EARLY_EVENT_BLANK) {
43 if (ld->ops->early_set_power)
44 ld->ops->early_set_power(ld,
45 *(int *)evdata->data);
46 } else if (event == FB_R_EARLY_EVENT_BLANK) {
47 if (ld->ops->r_early_set_power)
48 ld->ops->r_early_set_power(ld,
49 *(int *)evdata->data);
51 if (ld->ops->set_mode)
52 ld->ops->set_mode(ld, evdata->data);
55 mutex_unlock(&ld->ops_lock);
59 static int lcd_register_fb(struct lcd_device *ld)
61 memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
62 ld->fb_notif.notifier_call = fb_notifier_callback;
63 return fb_register_client(&ld->fb_notif);
66 static void lcd_unregister_fb(struct lcd_device *ld)
68 fb_unregister_client(&ld->fb_notif);
71 static int lcd_register_fb(struct lcd_device *ld)
76 static inline void lcd_unregister_fb(struct lcd_device *ld)
79 #endif /* CONFIG_FB */
81 static ssize_t lcd_power_show(struct device *dev, struct device_attribute *attr,
85 struct lcd_device *ld = to_lcd_device(dev);
87 mutex_lock(&ld->ops_lock);
88 if (ld->ops && ld->ops->get_power)
89 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
92 mutex_unlock(&ld->ops_lock);
97 static ssize_t lcd_power_store(struct device *dev,
98 struct device_attribute *attr, const char *buf, size_t count)
101 struct lcd_device *ld = to_lcd_device(dev);
104 rc = kstrtoul(buf, 0, &power);
110 mutex_lock(&ld->ops_lock);
111 if (ld->ops && ld->ops->set_power) {
112 pr_debug("set power to %lu\n", power);
113 ld->ops->set_power(ld, power);
116 mutex_unlock(&ld->ops_lock);
120 static DEVICE_ATTR_RW(lcd_power);
122 static ssize_t contrast_show(struct device *dev,
123 struct device_attribute *attr, char *buf)
126 struct lcd_device *ld = to_lcd_device(dev);
128 mutex_lock(&ld->ops_lock);
129 if (ld->ops && ld->ops->get_contrast)
130 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
131 mutex_unlock(&ld->ops_lock);
136 static ssize_t contrast_store(struct device *dev,
137 struct device_attribute *attr, const char *buf, size_t count)
140 struct lcd_device *ld = to_lcd_device(dev);
141 unsigned long contrast;
143 rc = kstrtoul(buf, 0, &contrast);
149 mutex_lock(&ld->ops_lock);
150 if (ld->ops && ld->ops->set_contrast) {
151 pr_debug("set contrast to %lu\n", contrast);
152 ld->ops->set_contrast(ld, contrast);
155 mutex_unlock(&ld->ops_lock);
159 static DEVICE_ATTR_RW(contrast);
161 static ssize_t max_contrast_show(struct device *dev,
162 struct device_attribute *attr, char *buf)
164 struct lcd_device *ld = to_lcd_device(dev);
166 return sprintf(buf, "%d\n", ld->props.max_contrast);
168 static DEVICE_ATTR_RO(max_contrast);
170 static struct class *lcd_class;
172 static void lcd_device_release(struct device *dev)
174 struct lcd_device *ld = to_lcd_device(dev);
178 static struct attribute *lcd_device_attrs[] = {
179 &dev_attr_lcd_power.attr,
180 &dev_attr_contrast.attr,
181 &dev_attr_max_contrast.attr,
184 ATTRIBUTE_GROUPS(lcd_device);
187 * lcd_device_register - register a new object of lcd_device class.
188 * @name: the name of the new object(must be the same as the name of the
189 * respective framebuffer device).
190 * @devdata: an optional pointer to be stored in the device. The
191 * methods may retrieve it by using lcd_get_data(ld).
192 * @ops: the lcd operations structure.
194 * Creates and registers a new lcd device. Returns either an ERR_PTR()
195 * or a pointer to the newly allocated device.
197 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
198 void *devdata, struct lcd_ops *ops)
200 struct lcd_device *new_ld;
203 pr_debug("lcd_device_register: name=%s\n", name);
205 new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
207 return ERR_PTR(-ENOMEM);
209 mutex_init(&new_ld->ops_lock);
210 mutex_init(&new_ld->update_lock);
212 new_ld->dev.class = lcd_class;
213 new_ld->dev.parent = parent;
214 new_ld->dev.release = lcd_device_release;
215 dev_set_name(&new_ld->dev, "%s", name);
216 dev_set_drvdata(&new_ld->dev, devdata);
220 rc = device_register(&new_ld->dev);
222 put_device(&new_ld->dev);
226 rc = lcd_register_fb(new_ld);
228 device_unregister(&new_ld->dev);
234 EXPORT_SYMBOL(lcd_device_register);
237 * lcd_device_unregister - unregisters a object of lcd_device class.
238 * @ld: the lcd device object to be unregistered and freed.
240 * Unregisters a previously registered via lcd_device_register object.
242 void lcd_device_unregister(struct lcd_device *ld)
247 mutex_lock(&ld->ops_lock);
249 mutex_unlock(&ld->ops_lock);
250 lcd_unregister_fb(ld);
252 device_unregister(&ld->dev);
254 EXPORT_SYMBOL(lcd_device_unregister);
256 static void devm_lcd_device_release(struct device *dev, void *res)
258 struct lcd_device *lcd = *(struct lcd_device **)res;
260 lcd_device_unregister(lcd);
263 static int devm_lcd_device_match(struct device *dev, void *res, void *data)
265 struct lcd_device **r = res;
271 * devm_lcd_device_register - resource managed lcd_device_register()
272 * @dev: the device to register
273 * @name: the name of the device
274 * @parent: a pointer to the parent device
275 * @devdata: an optional pointer to be stored for private driver use
276 * @ops: the lcd operations structure
278 * @return a struct lcd on success, or an ERR_PTR on error
280 * Managed lcd_device_register(). The lcd_device returned from this function
281 * are automatically freed on driver detach. See lcd_device_register()
282 * for more information.
284 struct lcd_device *devm_lcd_device_register(struct device *dev,
285 const char *name, struct device *parent,
286 void *devdata, struct lcd_ops *ops)
288 struct lcd_device **ptr, *lcd;
290 ptr = devres_alloc(devm_lcd_device_release, sizeof(*ptr), GFP_KERNEL);
292 return ERR_PTR(-ENOMEM);
294 lcd = lcd_device_register(name, parent, devdata, ops);
297 devres_add(dev, ptr);
304 EXPORT_SYMBOL(devm_lcd_device_register);
307 * devm_lcd_device_unregister - resource managed lcd_device_unregister()
308 * @dev: the device to unregister
309 * @ld: the lcd device to unregister
311 * Deallocated a lcd allocated with devm_lcd_device_register(). Normally
312 * this function will not need to be called and the resource management
313 * code will ensure that the resource is freed.
315 void devm_lcd_device_unregister(struct device *dev, struct lcd_device *ld)
319 rc = devres_release(dev, devm_lcd_device_release,
320 devm_lcd_device_match, ld);
323 EXPORT_SYMBOL(devm_lcd_device_unregister);
326 static void __exit lcd_class_exit(void)
328 class_destroy(lcd_class);
331 static int __init lcd_class_init(void)
333 lcd_class = class_create(THIS_MODULE, "lcd");
334 if (IS_ERR(lcd_class)) {
335 pr_warn("Unable to create backlight class; errno = %ld\n",
337 return PTR_ERR(lcd_class);
340 lcd_class->dev_groups = lcd_device_groups;
345 * if this is compiled into the kernel, we need to ensure that the
346 * class is registered before users of the class try to register lcd's
348 postcore_initcall(lcd_class_init);
349 module_exit(lcd_class_exit);
351 MODULE_LICENSE("GPL");
352 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
353 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");