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                         if (ld->ops->set_power)
  47                                 ld->ops->set_power(ld, *(int *)evdata->data);
  48                 } else {
  49                         if (ld->ops->set_mode)
  50                                 ld->ops->set_mode(ld, evdata->data);
  51                 }
  52         }
  53         mutex_unlock(&ld->ops_lock);
  54         return 0;
  55 }
  56
  57 static int lcd_register_fb(struct lcd_device *ld)
  58 {
  59         memset(&ld->fb_notif, 0, sizeof(ld->fb_notif));
  60         ld->fb_notif.notifier_call = fb_notifier_callback;
  61         return fb_register_client(&ld->fb_notif);
  62 }
  63
  64 static void lcd_unregister_fb(struct lcd_device *ld)
  65 {
  66         fb_unregister_client(&ld->fb_notif);
  67 }
  68 #else
  69 static int lcd_register_fb(struct lcd_device *ld)
  70 {
  71         return 0;
  72 }
  73
  74 static inline void lcd_unregister_fb(struct lcd_device *ld)
  75 {
  76 }
  77 #endif /* CONFIG_FB */
  78
  79 static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
  80                 char *buf)
  81 {
  82         int rc;
  83         struct lcd_device *ld = to_lcd_device(dev);
  84
  85         mutex_lock(&ld->ops_lock);
  86         if (ld->ops && ld->ops->get_power)
  87                 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
  88         else
  89                 rc = -ENXIO;
  90         mutex_unlock(&ld->ops_lock);
  91
  92         return rc;
  93 }
  94
  95 static ssize_t lcd_store_power(struct device *dev,
  96                 struct device_attribute *attr, const char *buf, size_t count)
  97 {
  98         int rc = -ENXIO;
  99         char *endp;
 100         struct lcd_device *ld = to_lcd_device(dev);
 101         int power = simple_strtoul(buf, &endp, 0);
 102         size_t size = endp - buf;
 103
 104         if (isspace(*endp))
 105                 size++;
 106         if (size != count)
 107                 return -EINVAL;
 108
 109         mutex_lock(&ld->ops_lock);
 110         if (ld->ops && ld->ops->set_power) {
 111                 pr_debug("lcd: set power to %d\n", power);
 112                 ld->ops->set_power(ld, power);
 113                 rc = count;
 114         }
 115         mutex_unlock(&ld->ops_lock);
 116
 117         return rc;
 118 }
 119
 120 static ssize_t lcd_show_contrast(struct device *dev,
 121                 struct device_attribute *attr, char *buf)
 122 {
 123         int rc = -ENXIO;
 124         struct lcd_device *ld = to_lcd_device(dev);
 125
 126         mutex_lock(&ld->ops_lock);
 127         if (ld->ops && ld->ops->get_contrast)
 128                 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
 129         mutex_unlock(&ld->ops_lock);
 130
 131         return rc;
 132 }
 133
 134 static ssize_t lcd_store_contrast(struct device *dev,
 135                 struct device_attribute *attr, const char *buf, size_t count)
 136 {
 137         int rc = -ENXIO;
 138         char *endp;
 139         struct lcd_device *ld = to_lcd_device(dev);
 140         int contrast = simple_strtoul(buf, &endp, 0);
 141         size_t size = endp - buf;
 142
 143         if (isspace(*endp))
 144                 size++;
 145         if (size != count)
 146                 return -EINVAL;
 147
 148         mutex_lock(&ld->ops_lock);
 149         if (ld->ops && ld->ops->set_contrast) {
 150                 pr_debug("lcd: set contrast to %d\n", contrast);
 151                 ld->ops->set_contrast(ld, contrast);
 152                 rc = count;
 153         }
 154         mutex_unlock(&ld->ops_lock);
 155
 156         return rc;
 157 }
 158
 159 static ssize_t lcd_show_max_contrast(struct device *dev,
 160                 struct device_attribute *attr, char *buf)
 161 {
 162         struct lcd_device *ld = to_lcd_device(dev);
 163
 164         return sprintf(buf, "%d\n", ld->props.max_contrast);
 165 }
 166
 167 static struct class *lcd_class;
 168
 169 static void lcd_device_release(struct device *dev)
 170 {
 171         struct lcd_device *ld = to_lcd_device(dev);
 172         kfree(ld);
 173 }
 174
 175 static struct device_attribute lcd_device_attributes[] = {
 176         __ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
 177         __ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 178         __ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
 179         __ATTR_NULL,
 180 };
 181
 182 /**
 183  * lcd_device_register - register a new object of lcd_device class.
 184  * @name: the name of the new object(must be the same as the name of the
 185  *   respective framebuffer device).
 186  * @devdata: an optional pointer to be stored in the device. The
 187  *   methods may retrieve it by using lcd_get_data(ld).
 188  * @ops: the lcd operations structure.
 189  *
 190  * Creates and registers a new lcd device. Returns either an ERR_PTR()
 191  * or a pointer to the newly allocated device.
 192  */
 193 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
 194                 void *devdata, struct lcd_ops *ops)
 195 {
 196         struct lcd_device *new_ld;
 197         int rc;
 198
 199         pr_debug("lcd_device_register: name=%s\n", name);
 200
 201         new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
 202         if (!new_ld)
 203                 return ERR_PTR(-ENOMEM);
 204
 205         mutex_init(&new_ld->ops_lock);
 206         mutex_init(&new_ld->update_lock);
 207
 208         new_ld->dev.class = lcd_class;
 209         new_ld->dev.parent = parent;
 210         new_ld->dev.release = lcd_device_release;
 211         dev_set_name(&new_ld->dev, name);
 212         dev_set_drvdata(&new_ld->dev, devdata);
 213
 214         rc = device_register(&new_ld->dev);
 215         if (rc) {
 216                 kfree(new_ld);
 217                 return ERR_PTR(rc);
 218         }
 219
 220         rc = lcd_register_fb(new_ld);
 221         if (rc) {
 222                 device_unregister(&new_ld->dev);
 223                 return ERR_PTR(rc);
 224         }
 225
 226         new_ld->ops = ops;
 227
 228         return new_ld;
 229 }
 230 EXPORT_SYMBOL(lcd_device_register);
 231
 232 /**
 233  * lcd_device_unregister - unregisters a object of lcd_device class.
 234  * @ld: the lcd device object to be unregistered and freed.
 235  *
 236  * Unregisters a previously registered via lcd_device_register object.
 237  */
 238 void lcd_device_unregister(struct lcd_device *ld)
 239 {
 240         if (!ld)
 241                 return;
 242
 243         mutex_lock(&ld->ops_lock);
 244         ld->ops = NULL;
 245         mutex_unlock(&ld->ops_lock);
 246         lcd_unregister_fb(ld);
 247
 248         device_unregister(&ld->dev);
 249 }
 250 EXPORT_SYMBOL(lcd_device_unregister);
 251
 252 static void __exit lcd_class_exit(void)
 253 {
 254         class_destroy(lcd_class);
 255 }
 256
 257 static int __init lcd_class_init(void)
 258 {
 259         lcd_class = class_create(THIS_MODULE, "lcd");
 260         if (IS_ERR(lcd_class)) {
 261                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 262                                 PTR_ERR(lcd_class));
 263                 return PTR_ERR(lcd_class);
 264         }
 265
 266         lcd_class->dev_attrs = lcd_device_attributes;
 267         return 0;
 268 }
 269
 270 /*
 271  * if this is compiled into the kernel, we need to ensure that the
 272  * class is registered before users of the class try to register lcd's
 273  */
 274 postcore_initcall(lcd_class_init);
 275 module_exit(lcd_class_exit);
 276
 277 MODULE_LICENSE("GPL");
 278 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 279 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");