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         struct lcd_device *ld = to_lcd_device(dev);
 101         unsigned long power;
 102
 103         rc = kstrtoul(buf, 0, &power);
 104         if (rc)
 105                 return rc;
 106
 107         mutex_lock(&ld->ops_lock);
 108         if (ld->ops && ld->ops->set_power) {
 109                 pr_debug("lcd: set power to %lu\n", power);
 110                 ld->ops->set_power(ld, power);
 111                 rc = count;
 112         }
 113         mutex_unlock(&ld->ops_lock);
 114
 115         return rc;
 116 }
 117
 118 static ssize_t lcd_show_contrast(struct device *dev,
 119                 struct device_attribute *attr, char *buf)
 120 {
 121         int rc = -ENXIO;
 122         struct lcd_device *ld = to_lcd_device(dev);
 123
 124         mutex_lock(&ld->ops_lock);
 125         if (ld->ops && ld->ops->get_contrast)
 126                 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
 127         mutex_unlock(&ld->ops_lock);
 128
 129         return rc;
 130 }
 131
 132 static ssize_t lcd_store_contrast(struct device *dev,
 133                 struct device_attribute *attr, const char *buf, size_t count)
 134 {
 135         int rc = -ENXIO;
 136         struct lcd_device *ld = to_lcd_device(dev);
 137         unsigned long contrast;
 138
 139         rc = kstrtoul(buf, 0, &contrast);
 140         if (rc)
 141                 return rc;
 142
 143         mutex_lock(&ld->ops_lock);
 144         if (ld->ops && ld->ops->set_contrast) {
 145                 pr_debug("lcd: set contrast to %lu\n", contrast);
 146                 ld->ops->set_contrast(ld, contrast);
 147                 rc = count;
 148         }
 149         mutex_unlock(&ld->ops_lock);
 150
 151         return rc;
 152 }
 153
 154 static ssize_t lcd_show_max_contrast(struct device *dev,
 155                 struct device_attribute *attr, char *buf)
 156 {
 157         struct lcd_device *ld = to_lcd_device(dev);
 158
 159         return sprintf(buf, "%d\n", ld->props.max_contrast);
 160 }
 161
 162 static struct class *lcd_class;
 163
 164 static void lcd_device_release(struct device *dev)
 165 {
 166         struct lcd_device *ld = to_lcd_device(dev);
 167         kfree(ld);
 168 }
 169
 170 static struct device_attribute lcd_device_attributes[] = {
 171         __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
 172         __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 173         __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
 174         __ATTR_NULL,
 175 };
 176
 177 /**
 178  * lcd_device_register - register a new object of lcd_device class.
 179  * @name: the name of the new object(must be the same as the name of the
 180  *   respective framebuffer device).
 181  * @devdata: an optional pointer to be stored in the device. The
 182  *   methods may retrieve it by using lcd_get_data(ld).
 183  * @ops: the lcd operations structure.
 184  *
 185  * Creates and registers a new lcd device. Returns either an ERR_PTR()
 186  * or a pointer to the newly allocated device.
 187  */
 188 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
 189                 void *devdata, struct lcd_ops *ops)
 190 {
 191         struct lcd_device *new_ld;
 192         int rc;
 193
 194         pr_debug("lcd_device_register: name=%s\n", name);
 195
 196         new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
 197         if (!new_ld)
 198                 return ERR_PTR(-ENOMEM);
 199
 200         mutex_init(&new_ld->ops_lock);
 201         mutex_init(&new_ld->update_lock);
 202
 203         new_ld->dev.class = lcd_class;
 204         new_ld->dev.parent = parent;
 205         new_ld->dev.release = lcd_device_release;
 206         dev_set_name(&new_ld->dev, name);
 207         dev_set_drvdata(&new_ld->dev, devdata);
 208
 209         rc = device_register(&new_ld->dev);
 210         if (rc) {
 211                 kfree(new_ld);
 212                 return ERR_PTR(rc);
 213         }
 214
 215         rc = lcd_register_fb(new_ld);
 216         if (rc) {
 217                 device_unregister(&new_ld->dev);
 218                 return ERR_PTR(rc);
 219         }
 220
 221         new_ld->ops = ops;
 222
 223         return new_ld;
 224 }
 225 EXPORT_SYMBOL(lcd_device_register);
 226
 227 /**
 228  * lcd_device_unregister - unregisters a object of lcd_device class.
 229  * @ld: the lcd device object to be unregistered and freed.
 230  *
 231  * Unregisters a previously registered via lcd_device_register object.
 232  */
 233 void lcd_device_unregister(struct lcd_device *ld)
 234 {
 235         if (!ld)
 236                 return;
 237
 238         mutex_lock(&ld->ops_lock);
 239         ld->ops = NULL;
 240         mutex_unlock(&ld->ops_lock);
 241         lcd_unregister_fb(ld);
 242
 243         device_unregister(&ld->dev);
 244 }
 245 EXPORT_SYMBOL(lcd_device_unregister);
 246
 247 static void __exit lcd_class_exit(void)
 248 {
 249         class_destroy(lcd_class);
 250 }
 251
 252 static int __init lcd_class_init(void)
 253 {
 254         lcd_class = class_create(THIS_MODULE, "lcd");
 255         if (IS_ERR(lcd_class)) {
 256                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 257                                 PTR_ERR(lcd_class));
 258                 return PTR_ERR(lcd_class);
 259         }
 260
 261         lcd_class->dev_attrs = lcd_device_attributes;
 262         return 0;
 263 }
 264
 265 /*
 266  * if this is compiled into the kernel, we need to ensure that the
 267  * class is registered before users of the class try to register lcd's
 268  */
 269 postcore_initcall(lcd_class_init);
 270 module_exit(lcd_class_exit);
 271
 272 MODULE_LICENSE("GPL");
 273 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 274 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");