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 static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
  18 {
  19         int rc;
  20         struct lcd_device *ld = to_lcd_device(cdev);
  21
  22         down(&ld->sem);
  23         if (likely(ld->props && ld->props->get_power))
  24                 rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
  25         else
  26                 rc = -ENXIO;
  27         up(&ld->sem);
  28
  29         return rc;
  30 }
  31
  32 static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
  33 {
  34         int rc = -ENXIO;
  35         char *endp;
  36         struct lcd_device *ld = to_lcd_device(cdev);
  37         int power = simple_strtoul(buf, &endp, 0);
  38         size_t size = endp - buf;
  39
  40         if (*endp && isspace(*endp))
  41                 size++;
  42         if (size != count)
  43                 return -EINVAL;
  44
  45         down(&ld->sem);
  46         if (likely(ld->props && ld->props->set_power)) {
  47                 pr_debug("lcd: set power to %d\n", power);
  48                 ld->props->set_power(ld, power);
  49                 rc = count;
  50         }
  51         up(&ld->sem);
  52
  53         return rc;
  54 }
  55
  56 static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
  57 {
  58         int rc = -ENXIO;
  59         struct lcd_device *ld = to_lcd_device(cdev);
  60
  61         down(&ld->sem);
  62         if (likely(ld->props && ld->props->get_contrast))
  63                 rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
  64         up(&ld->sem);
  65
  66         return rc;
  67 }
  68
  69 static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
  70 {
  71         int rc = -ENXIO;
  72         char *endp;
  73         struct lcd_device *ld = to_lcd_device(cdev);
  74         int contrast = simple_strtoul(buf, &endp, 0);
  75         size_t size = endp - buf;
  76
  77         if (*endp && isspace(*endp))
  78                 size++;
  79         if (size != count)
  80                 return -EINVAL;
  81
  82         down(&ld->sem);
  83         if (likely(ld->props && ld->props->set_contrast)) {
  84                 pr_debug("lcd: set contrast to %d\n", contrast);
  85                 ld->props->set_contrast(ld, contrast);
  86                 rc = count;
  87         }
  88         up(&ld->sem);
  89
  90         return rc;
  91 }
  92
  93 static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
  94 {
  95         int rc = -ENXIO;
  96         struct lcd_device *ld = to_lcd_device(cdev);
  97
  98         down(&ld->sem);
  99         if (likely(ld->props))
 100                 rc = sprintf(buf, "%d\n", ld->props->max_contrast);
 101         up(&ld->sem);
 102
 103         return rc;
 104 }
 105
 106 static void lcd_class_release(struct class_device *dev)
 107 {
 108         struct lcd_device *ld = to_lcd_device(dev);
 109         kfree(ld);
 110 }
 111
 112 static struct class lcd_class = {
 113         .name = "lcd",
 114         .release = lcd_class_release,
 115 };
 116
 117 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 118 {                                                               \
 119         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 120         .show   = _show,                                        \
 121         .store  = _store,                                       \
 122 }
 123
 124 static struct class_device_attribute lcd_class_device_attributes[] = {
 125         DECLARE_ATTR(power, 0644, lcd_show_power, lcd_store_power),
 126         DECLARE_ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 127         DECLARE_ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
 128 };
 129
 130 /* This callback gets called when something important happens inside a
 131  * framebuffer driver. We're looking if that important event is blanking,
 132  * and if it is, we're switching lcd power as well ...
 133  */
 134 static int fb_notifier_callback(struct notifier_block *self,
 135                                  unsigned long event, void *data)
 136 {
 137         struct lcd_device *ld;
 138         struct fb_event *evdata =(struct fb_event *)data;
 139
 140         /* If we aren't interested in this event, skip it immediately ... */
 141         if (event != FB_EVENT_BLANK)
 142                 return 0;
 143
 144         ld = container_of(self, struct lcd_device, fb_notif);
 145         down(&ld->sem);
 146         if (ld->props)
 147                 if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
 148                         ld->props->set_power(ld, *(int *)evdata->data);
 149         up(&ld->sem);
 150         return 0;
 151 }
 152
 153 /**
 154  * lcd_device_register - register a new object of lcd_device class.
 155  * @name: the name of the new object(must be the same as the name of the
 156  *   respective framebuffer device).
 157  * @devdata: an optional pointer to be stored in the class_device. The
 158  *   methods may retrieve it by using class_get_devdata(ld->class_dev).
 159  * @lp: the lcd properties structure.
 160  *
 161  * Creates and registers a new lcd class_device. Returns either an ERR_PTR()
 162  * or a pointer to the newly allocated device.
 163  */
 164 struct lcd_device *lcd_device_register(const char *name, void *devdata,
 165                                        struct lcd_properties *lp)
 166 {
 167         int i, rc;
 168         struct lcd_device *new_ld;
 169
 170         pr_debug("lcd_device_register: name=%s\n", name);
 171
 172         new_ld = kmalloc(sizeof(struct lcd_device), GFP_KERNEL);
 173         if (unlikely(!new_ld))
 174                 return ERR_PTR(-ENOMEM);
 175
 176         init_MUTEX(&new_ld->sem);
 177         new_ld->props = lp;
 178         memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev));
 179         new_ld->class_dev.class = &lcd_class;
 180         strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
 181         class_set_devdata(&new_ld->class_dev, devdata);
 182
 183         rc = class_device_register(&new_ld->class_dev);
 184         if (unlikely(rc)) {
 185 error:          kfree(new_ld);
 186                 return ERR_PTR(rc);
 187         }
 188
 189         memset(&new_ld->fb_notif, 0, sizeof(new_ld->fb_notif));
 190         new_ld->fb_notif.notifier_call = fb_notifier_callback;
 191
 192         rc = fb_register_client(&new_ld->fb_notif);
 193         if (unlikely(rc))
 194                 goto error;
 195
 196         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++) {
 197                 rc = class_device_create_file(&new_ld->class_dev,
 198                                               &lcd_class_device_attributes[i]);
 199                 if (unlikely(rc)) {
 200                         while (--i >= 0)
 201                                 class_device_remove_file(&new_ld->class_dev,
 202                                                          &lcd_class_device_attributes[i]);
 203                         class_device_unregister(&new_ld->class_dev);
 204                         /* No need to kfree(new_ld) since release() method was called */
 205                         return ERR_PTR(rc);
 206                 }
 207         }
 208
 209         return new_ld;
 210 }
 211 EXPORT_SYMBOL(lcd_device_register);
 212
 213 /**
 214  * lcd_device_unregister - unregisters a object of lcd_device class.
 215  * @ld: the lcd device object to be unregistered and freed.
 216  *
 217  * Unregisters a previously registered via lcd_device_register object.
 218  */
 219 void lcd_device_unregister(struct lcd_device *ld)
 220 {
 221         int i;
 222
 223         if (!ld)
 224                 return;
 225
 226         pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);
 227
 228         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++)
 229                 class_device_remove_file(&ld->class_dev,
 230                                          &lcd_class_device_attributes[i]);
 231
 232         down(&ld->sem);
 233         ld->props = NULL;
 234         up(&ld->sem);
 235
 236         fb_unregister_client(&ld->fb_notif);
 237
 238         class_device_unregister(&ld->class_dev);
 239 }
 240 EXPORT_SYMBOL(lcd_device_unregister);
 241
 242 static void __exit lcd_class_exit(void)
 243 {
 244         class_unregister(&lcd_class);
 245 }
 246
 247 static int __init lcd_class_init(void)
 248 {
 249         return class_register(&lcd_class);
 250 }
 251
 252 /*
 253  * if this is compiled into the kernel, we need to ensure that the
 254  * class is registered before users of the class try to register lcd's
 255  */
 256 postcore_initcall(lcd_class_init);
 257 module_exit(lcd_class_exit);
 258
 259 MODULE_LICENSE("GPL");
 260 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 261 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");