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 = -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
 189 /**
 190  * lcd_device_register - register a new object of lcd_device class.
 191  * @name: the name of the new object(must be the same as the name of the
 192  *   respective framebuffer device).
 193  * @devdata: an optional pointer to be stored in the device. The
 194  *   methods may retrieve it by using lcd_get_data(ld).
 195  * @ops: the lcd operations structure.
 196  *
 197  * Creates and registers a new lcd device. Returns either an ERR_PTR()
 198  * or a pointer to the newly allocated device.
 199  */
 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 }
 237 EXPORT_SYMBOL(lcd_device_register);
 238
 239 /**
 240  * lcd_device_unregister - unregisters a object of lcd_device class.
 241  * @ld: the lcd device object to be unregistered and freed.
 242  *
 243  * Unregisters a previously registered via lcd_device_register object.
 244  */
 245 void lcd_device_unregister(struct lcd_device *ld)
 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 }
 257 EXPORT_SYMBOL(lcd_device_unregister);
 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 <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 286 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");