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 <asm/bug.h>
  17
  18 static ssize_t lcd_show_power(struct class_device *cdev, char *buf)
  19 {
  20         int rc;
  21         struct lcd_device *ld = to_lcd_device(cdev);
  22
  23         down(&ld->sem);
  24         if (likely(ld->props && ld->props->get_power))
  25                 rc = sprintf(buf, "%d\n", ld->props->get_power(ld));
  26         else
  27                 rc = -ENXIO;
  28         up(&ld->sem);
  29
  30         return rc;
  31 }
  32
  33 static ssize_t lcd_store_power(struct class_device *cdev, const char *buf, size_t count)
  34 {
  35         int rc, power;
  36         char *endp;
  37         struct lcd_device *ld = to_lcd_device(cdev);
  38
  39         power = simple_strtoul(buf, &endp, 0);
  40         if (*endp && !isspace(*endp))
  41                 return -EINVAL;
  42
  43         down(&ld->sem);
  44         if (likely(ld->props && ld->props->set_power)) {
  45                 pr_debug("lcd: set power to %d\n", power);
  46                 ld->props->set_power(ld, power);
  47                 rc = count;
  48         } else
  49                 rc = -ENXIO;
  50         up(&ld->sem);
  51
  52         return rc;
  53 }
  54
  55 static ssize_t lcd_show_contrast(struct class_device *cdev, char *buf)
  56 {
  57         int rc;
  58         struct lcd_device *ld = to_lcd_device(cdev);
  59
  60         down(&ld->sem);
  61         if (likely(ld->props && ld->props->get_contrast))
  62                 rc = sprintf(buf, "%d\n", ld->props->get_contrast(ld));
  63         else
  64                 rc = -ENXIO;
  65         up(&ld->sem);
  66
  67         return rc;
  68 }
  69
  70 static ssize_t lcd_store_contrast(struct class_device *cdev, const char *buf, size_t count)
  71 {
  72         int rc, contrast;
  73         char *endp;
  74         struct lcd_device *ld = to_lcd_device(cdev);
  75
  76         contrast = simple_strtoul(buf, &endp, 0);
  77         if (*endp && !isspace(*endp))
  78                 return -EINVAL;
  79
  80         down(&ld->sem);
  81         if (likely(ld->props && ld->props->set_contrast)) {
  82                 pr_debug("lcd: set contrast to %d\n", contrast);
  83                 ld->props->set_contrast(ld, contrast);
  84                 rc = count;
  85         } else
  86                 rc = -ENXIO;
  87         up(&ld->sem);
  88
  89         return rc;
  90 }
  91
  92 static ssize_t lcd_show_max_contrast(struct class_device *cdev, char *buf)
  93 {
  94         int rc;
  95         struct lcd_device *ld = to_lcd_device(cdev);
  96
  97         down(&ld->sem);
  98         if (likely(ld->props))
  99                 rc = sprintf(buf, "%d\n", ld->props->max_contrast);
 100         else
 101                 rc = -ENXIO;
 102         up(&ld->sem);
 103
 104         return rc;
 105 }
 106
 107 static void lcd_class_release(struct class_device *dev)
 108 {
 109         struct lcd_device *ld = to_lcd_device(dev);
 110         kfree(ld);
 111 }
 112
 113 static struct class lcd_class = {
 114         .name = "lcd",
 115         .release = lcd_class_release,
 116 };
 117
 118 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 119 {                                                               \
 120         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 121         .show   = _show,                                        \
 122         .store  = _store,                                       \
 123 }
 124
 125 static struct class_device_attribute lcd_class_device_attributes[] = {
 126         DECLARE_ATTR(power, 0644, lcd_show_power, lcd_store_power),
 127         DECLARE_ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
 128         DECLARE_ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
 129 };
 130
 131 /* This callback gets called when something important happens inside a
 132  * framebuffer driver. We're looking if that important event is blanking,
 133  * and if it is, we're switching lcd power as well ...
 134  */
 135 static int fb_notifier_callback(struct notifier_block *self,
 136                                  unsigned long event, void *data)
 137 {
 138         struct lcd_device *ld;
 139         struct fb_event *evdata =(struct fb_event *)data;
 140
 141         /* If we aren't interested in this event, skip it immediately ... */
 142         if (event != FB_EVENT_BLANK)
 143                 return 0;
 144
 145         ld = container_of(self, struct lcd_device, fb_notif);
 146         down(&ld->sem);
 147         if (ld->props)
 148                 if (!ld->props->check_fb || ld->props->check_fb(evdata->info))
 149                         ld->props->set_power(ld, *(int *)evdata->data);
 150         up(&ld->sem);
 151         return 0;
 152 }
 153
 154 /**
 155  * lcd_device_register - register a new object of lcd_device class.
 156  * @name: the name of the new object(must be the same as the name of the
 157  *   respective framebuffer device).
 158  * @devdata: an optional pointer to be stored in the class_device. The
 159  *   methods may retrieve it by using class_get_devdata(ld->class_dev).
 160  * @lp: the lcd properties structure.
 161  *
 162  * Creates and registers a new lcd class_device. Returns either an ERR_PTR()
 163  * or a pointer to the newly allocated device.
 164  */
 165 struct lcd_device *lcd_device_register(const char *name, void *devdata,
 166                                        struct lcd_properties *lp)
 167 {
 168         int i, rc;
 169         struct lcd_device *new_ld;
 170
 171         pr_debug("lcd_device_register: name=%s\n", name);
 172
 173         new_ld = kmalloc(sizeof(struct lcd_device), GFP_KERNEL);
 174         if (unlikely(!new_ld))
 175                 return ERR_PTR(ENOMEM);
 176
 177         init_MUTEX(&new_ld->sem);
 178         new_ld->props = lp;
 179         memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev));
 180         new_ld->class_dev.class = &lcd_class;
 181         strlcpy(new_ld->class_dev.class_id, name, KOBJ_NAME_LEN);
 182         class_set_devdata(&new_ld->class_dev, devdata);
 183
 184         rc = class_device_register(&new_ld->class_dev);
 185         if (unlikely(rc)) {
 186 error:          kfree(new_ld);
 187                 return ERR_PTR(rc);
 188         }
 189
 190         memset(&new_ld->fb_notif, 0, sizeof(new_ld->fb_notif));
 191         new_ld->fb_notif.notifier_call = fb_notifier_callback;
 192
 193         rc = fb_register_client(&new_ld->fb_notif);
 194         if (unlikely(rc))
 195                 goto error;
 196
 197         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++) {
 198                 rc = class_device_create_file(&new_ld->class_dev,
 199                                               &lcd_class_device_attributes[i]);
 200                 if (unlikely(rc)) {
 201                         while (--i >= 0)
 202                                 class_device_remove_file(&new_ld->class_dev,
 203                                                          &lcd_class_device_attributes[i]);
 204                         class_device_unregister(&new_ld->class_dev);
 205                         /* No need to kfree(new_ld) since release() method was called */
 206                         return ERR_PTR(rc);
 207                 }
 208         }
 209
 210         return new_ld;
 211 }
 212 EXPORT_SYMBOL(lcd_device_register);
 213
 214 /**
 215  * lcd_device_unregister - unregisters a object of lcd_device class.
 216  * @ld: the lcd device object to be unregistered and freed.
 217  *
 218  * Unregisters a previously registered via lcd_device_register object.
 219  */
 220 void lcd_device_unregister(struct lcd_device *ld)
 221 {
 222         int i;
 223
 224         if (!ld)
 225                 return;
 226
 227         pr_debug("lcd_device_unregister: name=%s\n", ld->class_dev.class_id);
 228
 229         for (i = 0; i < ARRAY_SIZE(lcd_class_device_attributes); i++)
 230                 class_device_remove_file(&ld->class_dev,
 231                                          &lcd_class_device_attributes[i]);
 232
 233         down(&ld->sem);
 234         ld->props = NULL;
 235         up(&ld->sem);
 236
 237         fb_unregister_client(&ld->fb_notif);
 238
 239         class_device_unregister(&ld->class_dev);
 240 }
 241 EXPORT_SYMBOL(lcd_device_unregister);
 242
 243 static void __exit lcd_class_exit(void)
 244 {
 245         class_unregister(&lcd_class);
 246 }
 247
 248 static int __init lcd_class_init(void)
 249 {
 250         return class_register(&lcd_class);
 251 }
 252
 253 /*
 254  * if this is compiled into the kernel, we need to ensure that the
 255  * class is registered before users of the class try to register lcd's
 256  */
 257 postcore_initcall(lcd_class_init);
 258 module_exit(lcd_class_exit);
 259
 260 MODULE_LICENSE("GPL");
 261 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 262 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");