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(&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(&ld->fb_notif);
56}
57
58static void lcd_unregister_fb(struct lcd_device *ld)
59{
60	fb_unregister_client(&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, "%d\n", ld->ops->get_power(ld));
82	else
83		rc = -ENXIO;
84	mutex_unlock(&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(buf, 0, &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(&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, "%d\n", ld->ops->get_contrast(ld));
123	mutex_unlock(&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(buf, 0, &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(&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, "%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(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(sizeof(struct lcd_device), GFP_KERNEL);
199	if (!new_ld)
200		return ERR_PTR(-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(&new_ld->dev, "%s", name);
209	dev_set_drvdata(&new_ld->dev, devdata);
210
211	new_ld->ops = ops;
212
213	rc = device_register(&new_ld->dev);
214	if (rc) {
215		put_device(&new_ld->dev);
216		return ERR_PTR(rc);
217	}
218
219	rc = lcd_register_fb(new_ld);
220	if (rc) {
221		device_unregister(&new_ld->dev);
222		return ERR_PTR(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(&ld->ops_lock);
243	lcd_unregister_fb(ld);
244
245	device_unregister(&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(-ENOMEM);
286
287	lcd = lcd_device_register(name, parent, devdata, ops);
288	if (!IS_ERR(lcd)) {
289		*ptr = lcd;
290		devres_add(dev, ptr);
291	} else {
292		devres_free(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, devm_lcd_device_release,
313				devm_lcd_device_match, 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(lcd_class);
322}
323
324static int __init lcd_class_init(void)
325{
326	lcd_class = class_create("lcd");
327	if (IS_ERR(lcd_class)) {
328		pr_warn("Unable to create backlight class; errno = %ld\n",
329			PTR_ERR(lcd_class));
330		return PTR_ERR(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