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