1 /* 2 * Backlight 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/backlight.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 backlight_show_power(struct class_device *cdev, char *buf) 18 { 19 int rc; 20 struct backlight_device *bd = to_backlight_device(cdev); 21 22 down(&bd->sem); 23 if (likely(bd->props && bd->props->get_power)) 24 rc = sprintf(buf, "%d\n", bd->props->get_power(bd)); 25 else 26 rc = -ENXIO; 27 up(&bd->sem); 28 29 return rc; 30 } 31 32 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count) 33 { 34 int rc, power; 35 char *endp; 36 struct backlight_device *bd = to_backlight_device(cdev); 37 38 power = simple_strtoul(buf, &endp, 0); 39 if (*endp && !isspace(*endp)) 40 return -EINVAL; 41 42 down(&bd->sem); 43 if (likely(bd->props && bd->props->set_power)) { 44 pr_debug("backlight: set power to %d\n", power); 45 bd->props->set_power(bd, power); 46 rc = count; 47 } else 48 rc = -ENXIO; 49 up(&bd->sem); 50 51 return rc; 52 } 53 54 static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf) 55 { 56 int rc; 57 struct backlight_device *bd = to_backlight_device(cdev); 58 59 down(&bd->sem); 60 if (likely(bd->props && bd->props->get_brightness)) 61 rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd)); 62 else 63 rc = -ENXIO; 64 up(&bd->sem); 65 66 return rc; 67 } 68 69 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count) 70 { 71 int rc, brightness; 72 char *endp; 73 struct backlight_device *bd = to_backlight_device(cdev); 74 75 brightness = simple_strtoul(buf, &endp, 0); 76 if (*endp && !isspace(*endp)) 77 return -EINVAL; 78 79 down(&bd->sem); 80 if (likely(bd->props && bd->props->set_brightness)) { 81 pr_debug("backlight: set brightness to %d\n", brightness); 82 bd->props->set_brightness(bd, brightness); 83 rc = count; 84 } else 85 rc = -ENXIO; 86 up(&bd->sem); 87 88 return rc; 89 } 90 91 static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf) 92 { 93 int rc; 94 struct backlight_device *bd = to_backlight_device(cdev); 95 96 down(&bd->sem); 97 if (likely(bd->props)) 98 rc = sprintf(buf, "%d\n", bd->props->max_brightness); 99 else 100 rc = -ENXIO; 101 up(&bd->sem); 102 103 return rc; 104 } 105 106 static void backlight_class_release(struct class_device *dev) 107 { 108 struct backlight_device *bd = to_backlight_device(dev); 109 kfree(bd); 110 } 111 112 static struct class backlight_class = { 113 .name = "backlight", 114 .release = backlight_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 bl_class_device_attributes[] = { 125 DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power), 126 DECLARE_ATTR(brightness, 0644, backlight_show_brightness, backlight_store_brightness), 127 DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, 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 backlight power as well ... 133 */ 134 static int fb_notifier_callback(struct notifier_block *self, 135 unsigned long event, void *data) 136 { 137 struct backlight_device *bd; 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 bd = container_of(self, struct backlight_device, fb_notif); 145 down(&bd->sem); 146 if (bd->props) 147 if (!bd->props->check_fb || bd->props->check_fb(evdata->info)) 148 bd->props->set_power(bd, *(int *)evdata->data); 149 up(&bd->sem); 150 return 0; 151 } 152 153 /** 154 * backlight_device_register - create and register a new object of 155 * backlight_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(&bd->class_dev). 160 * @bp: the backlight properties structure. 161 * 162 * Creates and registers new backlight class_device. Returns either an 163 * ERR_PTR() or a pointer to the newly allocated device. 164 */ 165 struct backlight_device *backlight_device_register(const char *name, void *devdata, 166 struct backlight_properties *bp) 167 { 168 int i, rc; 169 struct backlight_device *new_bd; 170 171 pr_debug("backlight_device_alloc: name=%s\n", name); 172 173 new_bd = kmalloc(sizeof(struct backlight_device), GFP_KERNEL); 174 if (unlikely(!new_bd)) 175 return ERR_PTR(-ENOMEM); 176 177 init_MUTEX(&new_bd->sem); 178 new_bd->props = bp; 179 memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev)); 180 new_bd->class_dev.class = &backlight_class; 181 strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN); 182 class_set_devdata(&new_bd->class_dev, devdata); 183 184 rc = class_device_register(&new_bd->class_dev); 185 if (unlikely(rc)) { 186 error: kfree(new_bd); 187 return ERR_PTR(rc); 188 } 189 190 memset(&new_bd->fb_notif, 0, sizeof(new_bd->fb_notif)); 191 new_bd->fb_notif.notifier_call = fb_notifier_callback; 192 193 rc = fb_register_client(&new_bd->fb_notif); 194 if (unlikely(rc)) 195 goto error; 196 197 for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) { 198 rc = class_device_create_file(&new_bd->class_dev, 199 &bl_class_device_attributes[i]); 200 if (unlikely(rc)) { 201 while (--i >= 0) 202 class_device_remove_file(&new_bd->class_dev, 203 &bl_class_device_attributes[i]); 204 class_device_unregister(&new_bd->class_dev); 205 /* No need to kfree(new_bd) since release() method was called */ 206 return ERR_PTR(rc); 207 } 208 } 209 210 return new_bd; 211 } 212 EXPORT_SYMBOL(backlight_device_register); 213 214 /** 215 * backlight_device_unregister - unregisters a backlight device object. 216 * @bd: the backlight device object to be unregistered and freed. 217 * 218 * Unregisters a previously registered via backlight_device_register object. 219 */ 220 void backlight_device_unregister(struct backlight_device *bd) 221 { 222 int i; 223 224 if (!bd) 225 return; 226 227 pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id); 228 229 for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) 230 class_device_remove_file(&bd->class_dev, 231 &bl_class_device_attributes[i]); 232 233 down(&bd->sem); 234 bd->props = NULL; 235 up(&bd->sem); 236 237 fb_unregister_client(&bd->fb_notif); 238 239 class_device_unregister(&bd->class_dev); 240 } 241 EXPORT_SYMBOL(backlight_device_unregister); 242 243 static void __exit backlight_class_exit(void) 244 { 245 class_unregister(&backlight_class); 246 } 247 248 static int __init backlight_class_init(void) 249 { 250 return class_register(&backlight_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(backlight_class_init); 258 module_exit(backlight_class_exit); 259 260 MODULE_LICENSE("GPL"); 261 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>"); 262 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction"); 263