drivers/video/backlight/lcd.c

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