drivers/video/backlight/lcd.c: return ENXIO when ops functions cannot be called
[~shefty/rdma-dev.git] / drivers / video / backlight / lcd.c
1 /*
2  * LCD Lowlevel Control Abstraction
3  *
4  * Copyright (C) 2003,2004 Hewlett-Packard Company
5  *
6  */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/device.h>
13 #include <linux/lcd.h>
14 #include <linux/notifier.h>
15 #include <linux/ctype.h>
16 #include <linux/err.h>
17 #include <linux/fb.h>
18 #include <linux/slab.h>
19
20 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
21                            defined(CONFIG_LCD_CLASS_DEVICE_MODULE))
22 /* This callback gets called when something important happens inside a
23  * framebuffer driver. We're looking if that important event is blanking,
24  * and if it is, we're switching lcd power as well ...
25  */
26 static int fb_notifier_callback(struct notifier_block *self,
27                                  unsigned long event, void *data)
28 {
29         struct lcd_device *ld;
30         struct fb_event *evdata = data;
31
32         /* If we aren't interested in this event, skip it immediately ... */
33         switch (event) {
34         case FB_EVENT_BLANK:
35         case FB_EVENT_MODE_CHANGE:
36         case FB_EVENT_MODE_CHANGE_ALL:
37         case FB_EARLY_EVENT_BLANK:
38         case FB_R_EARLY_EVENT_BLANK:
39                 break;
40         default:
41                 return 0;
42         }
43
44         ld = container_of(self, struct lcd_device, fb_notif);
45         if (!ld->ops)
46                 return 0;
47
48         mutex_lock(&ld->ops_lock);
49         if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
50                 if (event == FB_EVENT_BLANK) {
51                         if (ld->ops->set_power)
52                                 ld->ops->set_power(ld, *(int *)evdata->data);
53                 } else if (event == FB_EARLY_EVENT_BLANK) {
54                         if (ld->ops->early_set_power)
55                                 ld->ops->early_set_power(ld,
56                                                 *(int *)evdata->data);
57                 } else if (event == FB_R_EARLY_EVENT_BLANK) {
58                         if (ld->ops->r_early_set_power)
59                                 ld->ops->r_early_set_power(ld,
60                                                 *(int *)evdata->data);
61                 } else {
62                         if (ld->ops->set_mode)
63                                 ld->ops->set_mode(ld, evdata->data);
64                 }
65         }
66         mutex_unlock(&ld->ops_lock);
67         return 0;
68 }
69
70 static int lcd_register_fb(struct lcd_device *ld)
71 {
72         memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
73         ld->fb_notif.notifier_call = fb_notifier_callback;
74         return fb_register_client(&ld->fb_notif);
75 }
76
77 static void lcd_unregister_fb(struct lcd_device *ld)
78 {
79         fb_unregister_client(&ld->fb_notif);
80 }
81 #else
82 static int lcd_register_fb(struct lcd_device *ld)
83 {
84         return 0;
85 }
86
87 static inline void lcd_unregister_fb(struct lcd_device *ld)
88 {
89 }
90 #endif /* CONFIG_FB */
91
92 static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
93                 char *buf)
94 {
95         int rc;
96         struct lcd_device *ld = to_lcd_device(dev);
97
98         mutex_lock(&ld->ops_lock);
99         if (ld->ops && ld->ops->get_power)
100                 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
101         else
102                 rc = -ENXIO;
103         mutex_unlock(&ld->ops_lock);
104
105         return rc;
106 }
107
108 static ssize_t lcd_store_power(struct device *dev,
109                 struct device_attribute *attr, const char *buf, size_t count)
110 {
111         int rc;
112         struct lcd_device *ld = to_lcd_device(dev);
113         unsigned long power;
114
115         rc = kstrtoul(buf, 0, &power);
116         if (rc)
117                 return rc;
118
119         rc = -ENXIO;
120
121         mutex_lock(&ld->ops_lock);
122         if (ld->ops && ld->ops->set_power) {
123                 pr_debug("set power to %lu\n", power);
124                 ld->ops->set_power(ld, power);
125                 rc = count;
126         }
127         mutex_unlock(&ld->ops_lock);
128
129         return rc;
130 }
131
132 static ssize_t lcd_show_contrast(struct device *dev,
133                 struct device_attribute *attr, char *buf)
134 {
135         int rc = -ENXIO;
136         struct lcd_device *ld = to_lcd_device(dev);
137
138         mutex_lock(&ld->ops_lock);
139         if (ld->ops && ld->ops->get_contrast)
140                 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
141         mutex_unlock(&ld->ops_lock);
142
143         return rc;
144 }
145
146 static ssize_t lcd_store_contrast(struct device *dev,
147                 struct device_attribute *attr, const char *buf, size_t count)
148 {
149         int rc;
150         struct lcd_device *ld = to_lcd_device(dev);
151         unsigned long contrast;
152
153         rc = kstrtoul(buf, 0, &contrast);
154         if (rc)
155                 return rc;
156
157         rc = -ENXIO;
158
159         mutex_lock(&ld->ops_lock);
160         if (ld->ops && ld->ops->set_contrast) {
161                 pr_debug("set contrast to %lu\n", contrast);
162                 ld->ops->set_contrast(ld, contrast);
163                 rc = count;
164         }
165         mutex_unlock(&ld->ops_lock);
166
167         return rc;
168 }
169
170 static ssize_t lcd_show_max_contrast(struct device *dev,
171                 struct device_attribute *attr, char *buf)
172 {
173         struct lcd_device *ld = to_lcd_device(dev);
174
175         return sprintf(buf, "%d\n", ld->props.max_contrast);
176 }
177
178 static struct class *lcd_class;
179
180 static void lcd_device_release(struct device *dev)
181 {
182         struct lcd_device *ld = to_lcd_device(dev);
183         kfree(ld);
184 }
185
186 static struct device_attribute lcd_device_attributes[] = {
187         __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
188         __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
189         __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
190         __ATTR_NULL,
191 };
192
193 /**
194  * lcd_device_register - register a new object of lcd_device class.
195  * @name: the name of the new object(must be the same as the name of the
196  *   respective framebuffer device).
197  * @devdata: an optional pointer to be stored in the device. The
198  *   methods may retrieve it by using lcd_get_data(ld).
199  * @ops: the lcd operations structure.
200  *
201  * Creates and registers a new lcd device. Returns either an ERR_PTR()
202  * or a pointer to the newly allocated device.
203  */
204 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
205                 void *devdata, struct lcd_ops *ops)
206 {
207         struct lcd_device *new_ld;
208         int rc;
209
210         pr_debug("lcd_device_register: name=%s\n", name);
211
212         new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
213         if (!new_ld)
214                 return ERR_PTR(-ENOMEM);
215
216         mutex_init(&new_ld->ops_lock);
217         mutex_init(&new_ld->update_lock);
218
219         new_ld->dev.class = lcd_class;
220         new_ld->dev.parent = parent;
221         new_ld->dev.release = lcd_device_release;
222         dev_set_name(&new_ld->dev, name);
223         dev_set_drvdata(&new_ld->dev, devdata);
224
225         rc = device_register(&new_ld->dev);
226         if (rc) {
227                 kfree(new_ld);
228                 return ERR_PTR(rc);
229         }
230
231         rc = lcd_register_fb(new_ld);
232         if (rc) {
233                 device_unregister(&new_ld->dev);
234                 return ERR_PTR(rc);
235         }
236
237         new_ld->ops = ops;
238
239         return new_ld;
240 }
241 EXPORT_SYMBOL(lcd_device_register);
242
243 /**
244  * lcd_device_unregister - unregisters a object of lcd_device class.
245  * @ld: the lcd device object to be unregistered and freed.
246  *
247  * Unregisters a previously registered via lcd_device_register object.
248  */
249 void lcd_device_unregister(struct lcd_device *ld)
250 {
251         if (!ld)
252                 return;
253
254         mutex_lock(&ld->ops_lock);
255         ld->ops = NULL;
256         mutex_unlock(&ld->ops_lock);
257         lcd_unregister_fb(ld);
258
259         device_unregister(&ld->dev);
260 }
261 EXPORT_SYMBOL(lcd_device_unregister);
262
263 static void __exit lcd_class_exit(void)
264 {
265         class_destroy(lcd_class);
266 }
267
268 static int __init lcd_class_init(void)
269 {
270         lcd_class = class_create(THIS_MODULE, "lcd");
271         if (IS_ERR(lcd_class)) {
272                 pr_warn("Unable to create backlight class; errno = %ld\n",
273                         PTR_ERR(lcd_class));
274                 return PTR_ERR(lcd_class);
275         }
276
277         lcd_class->dev_attrs = lcd_device_attributes;
278         return 0;
279 }
280
281 /*
282  * if this is compiled into the kernel, we need to ensure that the
283  * class is registered before users of the class try to register lcd's
284  */
285 postcore_initcall(lcd_class_init);
286 module_exit(lcd_class_exit);
287
288 MODULE_LICENSE("GPL");
289 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
290 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");