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