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         if (event != FB_EVENT_BLANK)
  31                 return 0;
  32
  33         ld = container_of(self, struct lcd_device, fb_notif);
  34         down(&ld->sem);
  35         if (ld->props)
  36                 if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
  37                         ld->props->set_power(ld, *(int *)evdata->data);
  38         up(&ld->sem);
  39         return 0;
  40 }
  41
  42 static int lcd_register_fb(struct lcd_device *ld)
  43 {
  44         memset(&ld->fb_notif, 0, sizeof(&ld->fb_notif));
  45         ld->fb_notif.notifier_call = fb_notifier_callback;
  46         return fb_register_client(&ld->fb_notif);
  47 }
  48
  49 static void lcd_unregister_fb(struct lcd_device *ld)
  50 {
  51         fb_unregister_client(&ld->fb_notif);
  52 }
  53 #else
  54 static int lcd_register_fb(struct lcd_device *ld)
  55 {
  56         return 0;
  57 }
  58
  59 static inline void lcd_unregister_fb(struct lcd_device *ld)
  60 {
  61 }
  62 #endif /* CONFIG_FB */
  63
  64 static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
  65 {
  66         int rc;
  67         struct lcd_device *ld = to_lcd_device(cdev);
  68
  69         down(&ld->sem);
  70         if (ld->props && ld->props->get_power)
  71                 rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
  72         else
  73                 rc = -ENXIO;
  74         up(&ld->sem);
  75
  76         return rc;
  77 }
  78
  79 static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
  80 {
  81         int rc = -ENXIO;
  82         char *endp;
  83         struct lcd_device *ld = to_lcd_device(cdev);
  84         int power = simple_strtoul(buf, &endp, 0);
  85         size_t size = endp - buf;
  86
  87         if (*endp && isspace(*endp))
  88                 size++;
  89         if (size != count)
  90                 return -EINVAL;
  91
  92         down(&ld->sem);
  93         if (ld->props && ld->props->set_power) {
  94                 pr_debug("lcd: set power to %d\n", power);
  95                 ld->props->set_power(ld, power);
  96                 rc = count;
  97         }
  98         up(&ld->sem);
  99
 100         return rc;
 101 }
 102
 103 static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
 104 {
 105         int rc = -ENXIO;
 106         struct lcd_device *ld = to_lcd_device(cdev);
 107
 108         down(&ld->sem);
 109         if (ld->props && ld->props->get_contrast)
 110                 rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
 111         up(&ld->sem);
 112
 113         return rc;
 114 }
 115
 116 static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
 117 {
 118         int rc = -ENXIO;
 119         char *endp;
 120         struct lcd_device *ld = to_lcd_device(cdev);
 121         int contrast = simple_strtoul(buf, &endp, 0);
 122         size_t size = endp - buf;
 123
 124         if (*endp && isspace(*endp))
 125                 size++;
 126         if (size != count)
 127                 return -EINVAL;
 128
 129         down(&ld->sem);
 130         if (ld->props && ld->props->set_contrast) {
 131                 pr_debug("lcd: set contrast to %d\n", contrast);
 132                 ld->props->set_contrast(ld, contrast);
 133                 rc = count;
 134         }
 135         up(&ld->sem);
 136
 137         return rc;
 138 }
 139
 140 static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
 141 {
 142         int rc = -ENXIO;
 143         struct lcd_device *ld = to_lcd_device(cdev);
 144
 145         down(&ld->sem);
 146         if (ld->props)
 147                 rc = sprintf(buf, "%d\n", ld->props->max_contrast);
 148         up(&ld->sem);
 149
 150         return rc;
 151 }
 152
 153 static void lcd_class_release(struct class_device *dev)
 154 {
 155         struct lcd_device *ld = to_lcd_device(dev);
 156         kfree(ld);
 157 }
 158
 159 static struct class lcd_class = {
 160         .name = "lcd",
 161         .release = lcd_class_release,
 162 };
 163
 164 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 165 {                                                               \
 166         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 167         .show   = _show,                                        \
 168         .store  = _store,                                       \
 169 }
 170
 171 static const struct class_device_attribute lcd_class_device_attributes[] = {
 172         DECLARE_ATTR(power, 0644, lcd_show_power, lcd_store_power),
 173         DECLARE_ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 174         DECLARE_ATTR(max_contrast, 0444, lcd_show_max_contrast, 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 class_device. The
 182  *   methods may retrieve it by using class_get_devdata(ld->class_dev).
 183  * @lp: the lcd properties structure.
 184  *
 185  * Creates and registers a new lcd class_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, void *devdata,
 189                                        struct lcd_properties *lp)
 190 {
 191         int i, rc;
 192         struct lcd_device *new_ld;
 193
 194         pr_debug("lcd_device_register: name=%s\n", name);
 195
 196         new_ld = kmalloc(sizeof(struct lcd_device), GFP_KERNEL);
 197         if (!new_ld)
 198                 return ERR_PTR(-ENOMEM);
 199
 200         init_MUTEX(&new_ld->sem);
 201         new_ld->props = lp;
 202         memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev));
 203         new_ld->class_dev.class = &lcd_class;
 204         strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
 205         class_set_devdata(&new_ld->class_dev, devdata);
 206
 207         rc = class_device_register(&new_ld->class_dev);
 208         if (rc) {
 209                 kfree(new_ld);
 210                 return ERR_PTR(rc);
 211         }
 212
 213         rc = lcd_register_fb(new_ld);
 214         if (rc) {
 215                 class_device_unregister(&new_ld->class_dev);
 216                 return ERR_PTR(rc);
 217         }
 218
 219         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++) {
 220                 rc = class_device_create_file(&new_ld->class_dev,
 221                                               &lcd_class_device_attributes[i]);
 222                 if (rc) {
 223                         while (--i >= 0)
 224                                 class_device_remove_file(&new_ld->class_dev,
 225                                                          &lcd_class_device_attributes[i]);
 226                         class_device_unregister(&new_ld->class_dev);
 227                         /* No need to kfree(new_ld) since release() method was called */
 228                         return ERR_PTR(rc);
 229                 }
 230         }
 231
 232         return new_ld;
 233 }
 234 EXPORT_SYMBOL(lcd_device_register);
 235
 236 /**
 237  * lcd_device_unregister - unregisters a object of lcd_device class.
 238  * @ld: the lcd device object to be unregistered and freed.
 239  *
 240  * Unregisters a previously registered via lcd_device_register object.
 241  */
 242 void lcd_device_unregister(struct lcd_device *ld)
 243 {
 244         int i;
 245
 246         if (!ld)
 247                 return;
 248
 249         pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);
 250
 251         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++)
 252                 class_device_remove_file(&ld->class_dev,
 253                                          &lcd_class_device_attributes[i]);
 254
 255         down(&ld->sem);
 256         ld->props = NULL;
 257         up(&ld->sem);
 258         lcd_unregister_fb(ld);
 259         class_device_unregister(&ld->class_dev);
 260 }
 261 EXPORT_SYMBOL(lcd_device_unregister);
 262
 263 static void __exit lcd_class_exit(void)
 264 {
 265         class_unregister(&lcd_class);
 266 }
 267
 268 static int __init lcd_class_init(void)
 269 {
 270         return class_register(&lcd_class);
 271 }
 272
 273 /*
 274  * if this is compiled into the kernel, we need to ensure that the
 275  * class is registered before users of the class try to register lcd's
 276  */
 277 postcore_initcall(lcd_class_init);
 278 module_exit(lcd_class_exit);
 279
 280 MODULE_LICENSE("GPL");
 281 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 282 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");