1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * LCD Lowlevel Control Abstraction
4 *
5 * Copyright (C) 2003,2004 Hewlett-Packard Company
6 *
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
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>
18#include <linux/fb.h>
19#include <linux/slab.h>
20
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 ...
26 */
27static int fb_notifier_callback(struct notifier_block *self,
28 unsigned long event, void *data)
29{
30 struct lcd_device *ld;
31 struct fb_event *evdata = data;
32
33 ld = container_of(self, struct lcd_device, fb_notif);
34 if (!ld->ops)
35 return 0;
36
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 {
43 if (ld->ops->set_mode)
44 ld->ops->set_mode(ld, evdata->data);
45 }
46 }
47 mutex_unlock(lock: &ld->ops_lock);
48 return 0;
49}
50
51static int lcd_register_fb(struct lcd_device *ld)
52{
53 memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
54 ld->fb_notif.notifier_call = fb_notifier_callback;
55 return fb_register_client(nb: &ld->fb_notif);
56}
57
58static void lcd_unregister_fb(struct lcd_device *ld)
59{
60 fb_unregister_client(nb: &ld->fb_notif);
61}
62#else
63static int lcd_register_fb(struct lcd_device *ld)
64{
65 return 0;
66}
67
68static inline void lcd_unregister_fb(struct lcd_device *ld)
69{
70}
71#endif /* CONFIG_FB */
72
73static ssize_t lcd_power_show(struct device *dev, struct device_attribute *attr,
74 char *buf)
75{
76 int rc;
77 struct lcd_device *ld = to_lcd_device(dev);
78
79 mutex_lock(&ld->ops_lock);
80 if (ld->ops && ld->ops->get_power)
81 rc = sprintf(buf, fmt: "%d\n", ld->ops->get_power(ld));
82 else
83 rc = -ENXIO;
84 mutex_unlock(lock: &ld->ops_lock);
85
86 return rc;
87}
88
89static ssize_t lcd_power_store(struct device *dev,
90 struct device_attribute *attr, const char *buf, size_t count)
91{
92 int rc;
93 struct lcd_device *ld = to_lcd_device(dev);
94 unsigned long power;
95
96 rc = kstrtoul(s: buf, base: 0, res: &power);
97 if (rc)
98 return rc;
99
100 rc = -ENXIO;
101
102 mutex_lock(&ld->ops_lock);
103 if (ld->ops && ld->ops->set_power) {
104 pr_debug("set power to %lu\n", power);
105 ld->ops->set_power(ld, power);
106 rc = count;
107 }
108 mutex_unlock(lock: &ld->ops_lock);
109
110 return rc;
111}
112static DEVICE_ATTR_RW(lcd_power);
113
114static ssize_t contrast_show(struct device *dev,
115 struct device_attribute *attr, char *buf)
116{
117 int rc = -ENXIO;
118 struct lcd_device *ld = to_lcd_device(dev);
119
120 mutex_lock(&ld->ops_lock);
121 if (ld->ops && ld->ops->get_contrast)
122 rc = sprintf(buf, fmt: "%d\n", ld->ops->get_contrast(ld));
123 mutex_unlock(lock: &ld->ops_lock);
124
125 return rc;
126}
127
128static ssize_t contrast_store(struct device *dev,
129 struct device_attribute *attr, const char *buf, size_t count)
130{
131 int rc;
132 struct lcd_device *ld = to_lcd_device(dev);
133 unsigned long contrast;
134
135 rc = kstrtoul(s: buf, base: 0, res: &contrast);
136 if (rc)
137 return rc;
138
139 rc = -ENXIO;
140
141 mutex_lock(&ld->ops_lock);
142 if (ld->ops && ld->ops->set_contrast) {
143 pr_debug("set contrast to %lu\n", contrast);
144 ld->ops->set_contrast(ld, contrast);
145 rc = count;
146 }
147 mutex_unlock(lock: &ld->ops_lock);
148
149 return rc;
150}
151static DEVICE_ATTR_RW(contrast);
152
153static ssize_t max_contrast_show(struct device *dev,
154 struct device_attribute *attr, char *buf)
155{
156 struct lcd_device *ld = to_lcd_device(dev);
157
158 return sprintf(buf, fmt: "%d\n", ld->props.max_contrast);
159}
160static DEVICE_ATTR_RO(max_contrast);
161
162static struct class *lcd_class;
163
164static void lcd_device_release(struct device *dev)
165{
166 struct lcd_device *ld = to_lcd_device(dev);
167 kfree(objp: ld);
168}
169
170static struct attribute *lcd_device_attrs[] = {
171 &dev_attr_lcd_power.attr,
172 &dev_attr_contrast.attr,
173 &dev_attr_max_contrast.attr,
174 NULL,
175};
176ATTRIBUTE_GROUPS(lcd_device);
177
178/**
179 * lcd_device_register - register a new object of lcd_device class.
180 * @name: the name of the new object(must be the same as the name of the
181 * respective framebuffer device).
182 * @parent: pointer to the parent's struct device .
183 * @devdata: an optional pointer to be stored in the device. The
184 * methods may retrieve it by using lcd_get_data(ld).
185 * @ops: the lcd operations structure.
186 *
187 * Creates and registers a new lcd device. Returns either an ERR_PTR()
188 * or a pointer to the newly allocated device.
189 */
190struct lcd_device *lcd_device_register(const char *name, struct device *parent,
191 void *devdata, struct lcd_ops *ops)
192{
193 struct lcd_device *new_ld;
194 int rc;
195
196 pr_debug("lcd_device_register: name=%s\n", name);
197
198 new_ld = kzalloc(size: sizeof(struct lcd_device), GFP_KERNEL);
199 if (!new_ld)
200 return ERR_PTR(error: -ENOMEM);
201
202 mutex_init(&new_ld->ops_lock);
203 mutex_init(&new_ld->update_lock);
204
205 new_ld->dev.class = lcd_class;
206 new_ld->dev.parent = parent;
207 new_ld->dev.release = lcd_device_release;
208 dev_set_name(dev: &new_ld->dev, name: "%s", name);
209 dev_set_drvdata(dev: &new_ld->dev, data: devdata);
210
211 new_ld->ops = ops;
212
213 rc = device_register(dev: &new_ld->dev);
214 if (rc) {
215 put_device(dev: &new_ld->dev);
216 return ERR_PTR(error: rc);
217 }
218
219 rc = lcd_register_fb(ld: new_ld);
220 if (rc) {
221 device_unregister(dev: &new_ld->dev);
222 return ERR_PTR(error: rc);
223 }
224
225 return new_ld;
226}
227EXPORT_SYMBOL(lcd_device_register);
228
229/**
230 * lcd_device_unregister - unregisters a object of lcd_device class.
231 * @ld: the lcd device object to be unregistered and freed.
232 *
233 * Unregisters a previously registered via lcd_device_register object.
234 */
235void lcd_device_unregister(struct lcd_device *ld)
236{
237 if (!ld)
238 return;
239
240 mutex_lock(&ld->ops_lock);
241 ld->ops = NULL;
242 mutex_unlock(lock: &ld->ops_lock);
243 lcd_unregister_fb(ld);
244
245 device_unregister(dev: &ld->dev);
246}
247EXPORT_SYMBOL(lcd_device_unregister);
248
249static void devm_lcd_device_release(struct device *dev, void *res)
250{
251 struct lcd_device *lcd = *(struct lcd_device **)res;
252
253 lcd_device_unregister(lcd);
254}
255
256static int devm_lcd_device_match(struct device *dev, void *res, void *data)
257{
258 struct lcd_device **r = res;
259
260 return *r == data;
261}
262
263/**
264 * devm_lcd_device_register - resource managed lcd_device_register()
265 * @dev: the device to register
266 * @name: the name of the device
267 * @parent: a pointer to the parent device
268 * @devdata: an optional pointer to be stored for private driver use
269 * @ops: the lcd operations structure
270 *
271 * @return a struct lcd on success, or an ERR_PTR on error
272 *
273 * Managed lcd_device_register(). The lcd_device returned from this function
274 * are automatically freed on driver detach. See lcd_device_register()
275 * for more information.
276 */
277struct lcd_device *devm_lcd_device_register(struct device *dev,
278 const char *name, struct device *parent,
279 void *devdata, struct lcd_ops *ops)
280{
281 struct lcd_device **ptr, *lcd;
282
283 ptr = devres_alloc(devm_lcd_device_release, sizeof(*ptr), GFP_KERNEL);
284 if (!ptr)
285 return ERR_PTR(error: -ENOMEM);
286
287 lcd = lcd_device_register(name, parent, devdata, ops);
288 if (!IS_ERR(ptr: lcd)) {
289 *ptr = lcd;
290 devres_add(dev, res: ptr);
291 } else {
292 devres_free(res: ptr);
293 }
294
295 return lcd;
296}
297EXPORT_SYMBOL(devm_lcd_device_register);
298
299/**
300 * devm_lcd_device_unregister - resource managed lcd_device_unregister()
301 * @dev: the device to unregister
302 * @ld: the lcd device to unregister
303 *
304 * Deallocated a lcd allocated with devm_lcd_device_register(). Normally
305 * this function will not need to be called and the resource management
306 * code will ensure that the resource is freed.
307 */
308void devm_lcd_device_unregister(struct device *dev, struct lcd_device *ld)
309{
310 int rc;
311
312 rc = devres_release(dev, release: devm_lcd_device_release,
313 match: devm_lcd_device_match, match_data: ld);
314 WARN_ON(rc);
315}
316EXPORT_SYMBOL(devm_lcd_device_unregister);
317
318
319static void __exit lcd_class_exit(void)
320{
321 class_destroy(cls: lcd_class);
322}
323
324static int __init lcd_class_init(void)
325{
326 lcd_class = class_create(name: "lcd");
327 if (IS_ERR(ptr: lcd_class)) {
328 pr_warn("Unable to create backlight class; errno = %ld\n",
329 PTR_ERR(lcd_class));
330 return PTR_ERR(ptr: lcd_class);
331 }
332
333 lcd_class->dev_groups = lcd_device_groups;
334 return 0;
335}
336
337/*
338 * if this is compiled into the kernel, we need to ensure that the
339 * class is registered before users of the class try to register lcd's
340 */
341postcore_initcall(lcd_class_init);
342module_exit(lcd_class_exit);
343
344MODULE_LICENSE("GPL");
345MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
346MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");
347

source code of linux/drivers/video/backlight/lcd.c