Linux Kernel  3.7.1
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lcd.c
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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:
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 {
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 = -ENXIO;
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  mutex_lock(&ld->ops_lock);
120  if (ld->ops && ld->ops->set_power) {
121  pr_debug("set power to %lu\n", power);
122  ld->ops->set_power(ld, power);
123  rc = count;
124  }
125  mutex_unlock(&ld->ops_lock);
126 
127  return rc;
128 }
129 
130 static ssize_t lcd_show_contrast(struct device *dev,
131  struct device_attribute *attr, char *buf)
132 {
133  int rc = -ENXIO;
134  struct lcd_device *ld = to_lcd_device(dev);
135 
136  mutex_lock(&ld->ops_lock);
137  if (ld->ops && ld->ops->get_contrast)
138  rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
139  mutex_unlock(&ld->ops_lock);
140 
141  return rc;
142 }
143 
144 static ssize_t lcd_store_contrast(struct device *dev,
145  struct device_attribute *attr, const char *buf, size_t count)
146 {
147  int rc = -ENXIO;
148  struct lcd_device *ld = to_lcd_device(dev);
149  unsigned long contrast;
150 
151  rc = kstrtoul(buf, 0, &contrast);
152  if (rc)
153  return rc;
154 
155  mutex_lock(&ld->ops_lock);
156  if (ld->ops && ld->ops->set_contrast) {
157  pr_debug("set contrast to %lu\n", contrast);
158  ld->ops->set_contrast(ld, contrast);
159  rc = count;
160  }
161  mutex_unlock(&ld->ops_lock);
162 
163  return rc;
164 }
165 
166 static ssize_t lcd_show_max_contrast(struct device *dev,
167  struct device_attribute *attr, char *buf)
168 {
169  struct lcd_device *ld = to_lcd_device(dev);
170 
171  return sprintf(buf, "%d\n", ld->props.max_contrast);
172 }
173 
174 static struct class *lcd_class;
175 
176 static void lcd_device_release(struct device *dev)
177 {
178  struct lcd_device *ld = to_lcd_device(dev);
179  kfree(ld);
180 }
181 
182 static struct device_attribute lcd_device_attributes[] = {
183  __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
184  __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
185  __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
186  __ATTR_NULL,
187 };
188 
200 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
201  void *devdata, struct lcd_ops *ops)
202 {
203  struct lcd_device *new_ld;
204  int rc;
205 
206  pr_debug("lcd_device_register: name=%s\n", name);
207 
208  new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
209  if (!new_ld)
210  return ERR_PTR(-ENOMEM);
211 
212  mutex_init(&new_ld->ops_lock);
213  mutex_init(&new_ld->update_lock);
214 
215  new_ld->dev.class = lcd_class;
216  new_ld->dev.parent = parent;
217  new_ld->dev.release = lcd_device_release;
218  dev_set_name(&new_ld->dev, name);
219  dev_set_drvdata(&new_ld->dev, devdata);
220 
221  rc = device_register(&new_ld->dev);
222  if (rc) {
223  kfree(new_ld);
224  return ERR_PTR(rc);
225  }
226 
227  rc = lcd_register_fb(new_ld);
228  if (rc) {
229  device_unregister(&new_ld->dev);
230  return ERR_PTR(rc);
231  }
232 
233  new_ld->ops = ops;
234 
235  return new_ld;
236 }
238 
246 {
247  if (!ld)
248  return;
249 
250  mutex_lock(&ld->ops_lock);
251  ld->ops = NULL;
252  mutex_unlock(&ld->ops_lock);
253  lcd_unregister_fb(ld);
254 
255  device_unregister(&ld->dev);
256 }
258 
259 static void __exit lcd_class_exit(void)
260 {
261  class_destroy(lcd_class);
262 }
263 
264 static int __init lcd_class_init(void)
265 {
266  lcd_class = class_create(THIS_MODULE, "lcd");
267  if (IS_ERR(lcd_class)) {
268  pr_warn("Unable to create backlight class; errno = %ld\n",
269  PTR_ERR(lcd_class));
270  return PTR_ERR(lcd_class);
271  }
272 
273  lcd_class->dev_attrs = lcd_device_attributes;
274  return 0;
275 }
276 
277 /*
278  * if this is compiled into the kernel, we need to ensure that the
279  * class is registered before users of the class try to register lcd's
280  */
281 postcore_initcall(lcd_class_init);
282 module_exit(lcd_class_exit);
283 
284 MODULE_LICENSE("GPL");
285 MODULE_AUTHOR("Jamey Hicks <[email protected]>, Andrew Zabolotny <[email protected]>");
286 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");