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         mutex_lock(&ld->ops_lock);
  44         if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
  45                 if (event == FB_EVENT_BLANK)
  46                         ld->ops->set_power(ld, *(int *)evdata->data);
  47                 else
  48                         ld->ops->set_mode(ld, evdata->data);
  49         }
  50         mutex_unlock(&ld->ops_lock);
  51         return 0;
  52 }
  53
  54 static int lcd_register_fb(struct lcd_device *ld)
  55 {
  56         memset(&ld->fb_notif, 0, sizeof(&ld->fb_notif));
  57         ld->fb_notif.notifier_call = fb_notifier_callback;
  58         return fb_register_client(&ld->fb_notif);
  59 }
  60
  61 static void lcd_unregister_fb(struct lcd_device *ld)
  62 {
  63         fb_unregister_client(&ld->fb_notif);
  64 }
  65 #else
  66 static int lcd_register_fb(struct lcd_device *ld)
  67 {
  68         return 0;
  69 }
  70
  71 static inline void lcd_unregister_fb(struct lcd_device *ld)
  72 {
  73 }
  74 #endif /* CONFIG_FB */
  75
  76 static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
  77                 char *buf)
  78 {
  79         int rc;
  80         struct lcd_device *ld = to_lcd_device(dev);
  81
  82         mutex_lock(&ld->ops_lock);
  83         if (ld->ops && ld->ops->get_power)
  84                 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
  85         else
  86                 rc = -ENXIO;
  87         mutex_unlock(&ld->ops_lock);
  88
  89         return rc;
  90 }
  91
  92 static ssize_t lcd_store_power(struct device *dev,
  93                 struct device_attribute *attr, const char *buf, size_t count)
  94 {
  95         int rc = -ENXIO;
  96         char *endp;
  97         struct lcd_device *ld = to_lcd_device(dev);
  98         int power = simple_strtoul(buf, &endp, 0);
  99         size_t size = endp - buf;
 100
 101         if (*endp && isspace(*endp))
 102                 size++;
 103         if (size != count)
 104                 return -EINVAL;
 105
 106         mutex_lock(&ld->ops_lock);
 107         if (ld->ops && ld->ops->set_power) {
 108                 pr_debug("lcd: set power to %d\n", power);
 109                 ld->ops->set_power(ld, power);
 110                 rc = count;
 111         }
 112         mutex_unlock(&ld->ops_lock);
 113
 114         return rc;
 115 }
 116
 117 static ssize_t lcd_show_contrast(struct device *dev,
 118                 struct device_attribute *attr, char *buf)
 119 {
 120         int rc = -ENXIO;
 121         struct lcd_device *ld = to_lcd_device(dev);
 122
 123         mutex_lock(&ld->ops_lock);
 124         if (ld->ops && ld->ops->get_contrast)
 125                 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
 126         mutex_unlock(&ld->ops_lock);
 127
 128         return rc;
 129 }
 130
 131 static ssize_t lcd_store_contrast(struct device *dev,
 132                 struct device_attribute *attr, const char *buf, size_t count)
 133 {
 134         int rc = -ENXIO;
 135         char *endp;
 136         struct lcd_device *ld = to_lcd_device(dev);
 137         int contrast = simple_strtoul(buf, &endp, 0);
 138         size_t size = endp - buf;
 139
 140         if (*endp && isspace(*endp))
 141                 size++;
 142         if (size != count)
 143                 return -EINVAL;
 144
 145         mutex_lock(&ld->ops_lock);
 146         if (ld->ops && ld->ops->set_contrast) {
 147                 pr_debug("lcd: set contrast to %d\n", contrast);
 148                 ld->ops->set_contrast(ld, contrast);
 149                 rc = count;
 150         }
 151         mutex_unlock(&ld->ops_lock);
 152
 153         return rc;
 154 }
 155
 156 static ssize_t lcd_show_max_contrast(struct device *dev,
 157                 struct device_attribute *attr, char *buf)
 158 {
 159         struct lcd_device *ld = to_lcd_device(dev);
 160
 161         return sprintf(buf, "%d\n", ld->props.max_contrast);
 162 }
 163
 164 static struct class *lcd_class;
 165
 166 static void lcd_device_release(struct device *dev)
 167 {
 168         struct lcd_device *ld = to_lcd_device(dev);
 169         kfree(ld);
 170 }
 171
 172 static struct device_attribute lcd_device_attributes[] = {
 173         __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
 174         __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 175         __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
 176         __ATTR_NULL,
 177 };
 178
 179 /**
 180  * lcd_device_register - register a new object of lcd_device class.
 181  * @name: the name of the new object(must be the same as the name of the
 182  *   respective framebuffer 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  */
 190 struct 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         strlcpy(new_ld->dev.bus_id, name, BUS_ID_SIZE);
 209         dev_set_drvdata(&new_ld->dev, devdata);
 210
 211         rc = device_register(&new_ld->dev);
 212         if (rc) {
 213                 kfree(new_ld);
 214                 return ERR_PTR(rc);
 215         }
 216
 217         rc = lcd_register_fb(new_ld);
 218         if (rc) {
 219                 device_unregister(&new_ld->dev);
 220                 return ERR_PTR(rc);
 221         }
 222
 223         new_ld->ops = ops;
 224
 225         return new_ld;
 226 }
 227 EXPORT_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  */
 235 void 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 }
 247 EXPORT_SYMBOL(lcd_device_unregister);
 248
 249 static void __exit lcd_class_exit(void)
 250 {
 251         class_destroy(lcd_class);
 252 }
 253
 254 static int __init lcd_class_init(void)
 255 {
 256         lcd_class = class_create(THIS_MODULE, "lcd");
 257         if (IS_ERR(lcd_class)) {
 258                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 259                                 PTR_ERR(lcd_class));
 260                 return PTR_ERR(lcd_class);
 261         }
 262
 263         lcd_class->dev_attrs = lcd_device_attributes;
 264         return 0;
 265 }
 266
 267 /*
 268  * if this is compiled into the kernel, we need to ensure that the
 269  * class is registered before users of the class try to register lcd's
 270  */
 271 postcore_initcall(lcd_class_init);
 272 module_exit(lcd_class_exit);
 273
 274 MODULE_LICENSE("GPL");
 275 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 276 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");