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 /* If we aren't interested in this event, skip it immediately ... */
36 case FB_EVENT_MODE_CHANGE:
37 case FB_EVENT_MODE_CHANGE_ALL:
38 case FB_EARLY_EVENT_BLANK:
39 case FB_R_EARLY_EVENT_BLANK:
45 ld = container_of(self, struct lcd_device, fb_notif);
49 mutex_lock(&ld->ops_lock);
50 if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
51 if (event == FB_EVENT_BLANK) {
52 if (ld->ops->set_power)
53 ld->ops->set_power(ld, *(int *)evdata->data);
54 } else if (event == FB_EARLY_EVENT_BLANK) {
55 if (ld->ops->early_set_power)
56 ld->ops->early_set_power(ld,
57 *(int *)evdata->data);
58 } else if (event == FB_R_EARLY_EVENT_BLANK) {
59 if (ld->ops->r_early_set_power)
60 ld->ops->r_early_set_power(ld,
61 *(int *)evdata->data);
63 if (ld->ops->set_mode)
64 ld->ops->set_mode(ld, evdata->data);
67 mutex_unlock(&ld->ops_lock);
71 static int lcd_register_fb(struct lcd_device *ld)
73 memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
74 ld->fb_notif.notifier_call = fb_notifier_callback;
75 return fb_register_client(&ld->fb_notif);
78 static void lcd_unregister_fb(struct lcd_device *ld)
80 fb_unregister_client(&ld->fb_notif);
83 static int lcd_register_fb(struct lcd_device *ld)
88 static inline void lcd_unregister_fb(struct lcd_device *ld)
91 #endif /* CONFIG_FB */
93 static ssize_t lcd_power_show(struct device *dev, struct device_attribute *attr,
97 struct lcd_device *ld = to_lcd_device(dev);
99 mutex_lock(&ld->ops_lock);
100 if (ld->ops && ld->ops->get_power)
101 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
104 mutex_unlock(&ld->ops_lock);
109 static ssize_t lcd_power_store(struct device *dev,
110 struct device_attribute *attr, const char *buf, size_t count)
113 struct lcd_device *ld = to_lcd_device(dev);
116 rc = kstrtoul(buf, 0, &power);
122 mutex_lock(&ld->ops_lock);
123 if (ld->ops && ld->ops->set_power) {
124 pr_debug("set power to %lu\n", power);
125 ld->ops->set_power(ld, power);
128 mutex_unlock(&ld->ops_lock);
132 static DEVICE_ATTR_RW(lcd_power);
134 static ssize_t contrast_show(struct device *dev,
135 struct device_attribute *attr, char *buf)
138 struct lcd_device *ld = to_lcd_device(dev);
140 mutex_lock(&ld->ops_lock);
141 if (ld->ops && ld->ops->get_contrast)
142 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
143 mutex_unlock(&ld->ops_lock);
148 static ssize_t contrast_store(struct device *dev,
149 struct device_attribute *attr, const char *buf, size_t count)
152 struct lcd_device *ld = to_lcd_device(dev);
153 unsigned long contrast;
155 rc = kstrtoul(buf, 0, &contrast);
161 mutex_lock(&ld->ops_lock);
162 if (ld->ops && ld->ops->set_contrast) {
163 pr_debug("set contrast to %lu\n", contrast);
164 ld->ops->set_contrast(ld, contrast);
167 mutex_unlock(&ld->ops_lock);
171 static DEVICE_ATTR_RW(contrast);
173 static ssize_t max_contrast_show(struct device *dev,
174 struct device_attribute *attr, char *buf)
176 struct lcd_device *ld = to_lcd_device(dev);
178 return sprintf(buf, "%d\n", ld->props.max_contrast);
180 static DEVICE_ATTR_RO(max_contrast);
182 static struct class *lcd_class;
184 static void lcd_device_release(struct device *dev)
186 struct lcd_device *ld = to_lcd_device(dev);
190 static struct attribute *lcd_device_attrs[] = {
191 &dev_attr_lcd_power.attr,
192 &dev_attr_contrast.attr,
193 &dev_attr_max_contrast.attr,
196 ATTRIBUTE_GROUPS(lcd_device);
199 * lcd_device_register - register a new object of lcd_device class.
200 * @name: the name of the new object(must be the same as the name of the
201 * respective framebuffer device).
202 * @devdata: an optional pointer to be stored in the device. The
203 * methods may retrieve it by using lcd_get_data(ld).
204 * @ops: the lcd operations structure.
206 * Creates and registers a new lcd device. Returns either an ERR_PTR()
207 * or a pointer to the newly allocated device.
209 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
210 void *devdata, struct lcd_ops *ops)
212 struct lcd_device *new_ld;
215 pr_debug("lcd_device_register: name=%s\n", name);
217 new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
219 return ERR_PTR(-ENOMEM);
221 mutex_init(&new_ld->ops_lock);
222 mutex_init(&new_ld->update_lock);
224 new_ld->dev.class = lcd_class;
225 new_ld->dev.parent = parent;
226 new_ld->dev.release = lcd_device_release;
227 dev_set_name(&new_ld->dev, "%s", name);
228 dev_set_drvdata(&new_ld->dev, devdata);
232 rc = device_register(&new_ld->dev);
234 put_device(&new_ld->dev);
238 rc = lcd_register_fb(new_ld);
240 device_unregister(&new_ld->dev);
246 EXPORT_SYMBOL(lcd_device_register);
249 * lcd_device_unregister - unregisters a object of lcd_device class.
250 * @ld: the lcd device object to be unregistered and freed.
252 * Unregisters a previously registered via lcd_device_register object.
254 void lcd_device_unregister(struct lcd_device *ld)
259 mutex_lock(&ld->ops_lock);
261 mutex_unlock(&ld->ops_lock);
262 lcd_unregister_fb(ld);
264 device_unregister(&ld->dev);
266 EXPORT_SYMBOL(lcd_device_unregister);
268 static void devm_lcd_device_release(struct device *dev, void *res)
270 struct lcd_device *lcd = *(struct lcd_device **)res;
272 lcd_device_unregister(lcd);
275 static int devm_lcd_device_match(struct device *dev, void *res, void *data)
277 struct lcd_device **r = res;
283 * devm_lcd_device_register - resource managed lcd_device_register()
284 * @dev: the device to register
285 * @name: the name of the device
286 * @parent: a pointer to the parent device
287 * @devdata: an optional pointer to be stored for private driver use
288 * @ops: the lcd operations structure
290 * @return a struct lcd on success, or an ERR_PTR on error
292 * Managed lcd_device_register(). The lcd_device returned from this function
293 * are automatically freed on driver detach. See lcd_device_register()
294 * for more information.
296 struct lcd_device *devm_lcd_device_register(struct device *dev,
297 const char *name, struct device *parent,
298 void *devdata, struct lcd_ops *ops)
300 struct lcd_device **ptr, *lcd;
302 ptr = devres_alloc(devm_lcd_device_release, sizeof(*ptr), GFP_KERNEL);
304 return ERR_PTR(-ENOMEM);
306 lcd = lcd_device_register(name, parent, devdata, ops);
309 devres_add(dev, ptr);
316 EXPORT_SYMBOL(devm_lcd_device_register);
319 * devm_lcd_device_unregister - resource managed lcd_device_unregister()
320 * @dev: the device to unregister
321 * @ld: the lcd device to unregister
323 * Deallocated a lcd allocated with devm_lcd_device_register(). Normally
324 * this function will not need to be called and the resource management
325 * code will ensure that the resource is freed.
327 void devm_lcd_device_unregister(struct device *dev, struct lcd_device *ld)
331 rc = devres_release(dev, devm_lcd_device_release,
332 devm_lcd_device_match, ld);
335 EXPORT_SYMBOL(devm_lcd_device_unregister);
338 static void __exit lcd_class_exit(void)
340 class_destroy(lcd_class);
343 static int __init lcd_class_init(void)
345 lcd_class = class_create(THIS_MODULE, "lcd");
346 if (IS_ERR(lcd_class)) {
347 pr_warn("Unable to create backlight class; errno = %ld\n",
349 return PTR_ERR(lcd_class);
352 lcd_class->dev_groups = lcd_device_groups;
357 * if this is compiled into the kernel, we need to ensure that the
358 * class is registered before users of the class try to register lcd's
360 postcore_initcall(lcd_class_init);
361 module_exit(lcd_class_exit);
363 MODULE_LICENSE("GPL");
364 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
365 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");