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