1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * LCD Lowlevel Control Abstraction 4 * 5 * Copyright (C) 2003,2004 Hewlett-Packard Company 6 * 7 */ 8 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 11 #include <linux/module.h> 12 #include <linux/init.h> 13 #include <linux/device.h> 14 #include <linux/lcd.h> 15 #include <linux/notifier.h> 16 #include <linux/ctype.h> 17 #include <linux/err.h> 18 #include <linux/fb.h> 19 #include <linux/slab.h> 20 21 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \ 22 defined(CONFIG_LCD_CLASS_DEVICE_MODULE)) 23 static int to_lcd_power(int fb_blank) 24 { 25 switch (fb_blank) { 26 case FB_BLANK_UNBLANK: 27 return LCD_POWER_ON; 28 /* deprecated; TODO: should become 'off' */ 29 case FB_BLANK_NORMAL: 30 return LCD_POWER_REDUCED; 31 case FB_BLANK_VSYNC_SUSPEND: 32 return LCD_POWER_REDUCED_VSYNC_SUSPEND; 33 /* 'off' */ 34 case FB_BLANK_HSYNC_SUSPEND: 35 case FB_BLANK_POWERDOWN: 36 default: 37 return LCD_POWER_OFF; 38 } 39 } 40 41 /* This callback gets called when something important happens inside a 42 * framebuffer driver. We're looking if that important event is blanking, 43 * and if it is, we're switching lcd power as well ... 44 */ 45 static int fb_notifier_callback(struct notifier_block *self, 46 unsigned long event, void *data) 47 { 48 struct lcd_device *ld = container_of(self, struct lcd_device, fb_notif); 49 struct fb_event *evdata = data; 50 struct fb_info *info = evdata->info; 51 struct lcd_device *fb_lcd = fb_lcd_device(info); 52 53 guard(mutex)(&ld->ops_lock); 54 55 if (!ld->ops) 56 return 0; 57 if (ld->ops->controls_device && !ld->ops->controls_device(ld, info->device)) 58 return 0; 59 if (fb_lcd && fb_lcd != ld) 60 return 0; 61 62 if (event == FB_EVENT_BLANK) { 63 int power = to_lcd_power(*(int *)evdata->data); 64 65 if (ld->ops->set_power) 66 ld->ops->set_power(ld, power); 67 } else { 68 const struct fb_videomode *videomode = evdata->data; 69 70 if (ld->ops->set_mode) 71 ld->ops->set_mode(ld, videomode->xres, videomode->yres); 72 } 73 74 return 0; 75 } 76 77 static int lcd_register_fb(struct lcd_device *ld) 78 { 79 memset(&ld->fb_notif, 0, sizeof(ld->fb_notif)); 80 ld->fb_notif.notifier_call = fb_notifier_callback; 81 return fb_register_client(&ld->fb_notif); 82 } 83 84 static void lcd_unregister_fb(struct lcd_device *ld) 85 { 86 fb_unregister_client(&ld->fb_notif); 87 } 88 #else 89 static int lcd_register_fb(struct lcd_device *ld) 90 { 91 return 0; 92 } 93 94 static inline void lcd_unregister_fb(struct lcd_device *ld) 95 { 96 } 97 #endif /* CONFIG_FB */ 98 99 static ssize_t lcd_power_show(struct device *dev, struct device_attribute *attr, 100 char *buf) 101 { 102 int rc; 103 struct lcd_device *ld = to_lcd_device(dev); 104 105 mutex_lock(&ld->ops_lock); 106 if (ld->ops && ld->ops->get_power) 107 rc = sprintf(buf, "%d\n", ld->ops->get_power(ld)); 108 else 109 rc = -ENXIO; 110 mutex_unlock(&ld->ops_lock); 111 112 return rc; 113 } 114 115 static ssize_t lcd_power_store(struct device *dev, 116 struct device_attribute *attr, const char *buf, size_t count) 117 { 118 int rc; 119 struct lcd_device *ld = to_lcd_device(dev); 120 unsigned long power; 121 122 rc = kstrtoul(buf, 0, &power); 123 if (rc) 124 return rc; 125 126 rc = -ENXIO; 127 128 mutex_lock(&ld->ops_lock); 129 if (ld->ops && ld->ops->set_power) { 130 pr_debug("set power to %lu\n", power); 131 ld->ops->set_power(ld, power); 132 rc = count; 133 } 134 mutex_unlock(&ld->ops_lock); 135 136 return rc; 137 } 138 static DEVICE_ATTR_RW(lcd_power); 139 140 static ssize_t contrast_show(struct device *dev, 141 struct device_attribute *attr, char *buf) 142 { 143 int rc = -ENXIO; 144 struct lcd_device *ld = to_lcd_device(dev); 145 146 mutex_lock(&ld->ops_lock); 147 if (ld->ops && ld->ops->get_contrast) 148 rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld)); 149 mutex_unlock(&ld->ops_lock); 150 151 return rc; 152 } 153 154 static ssize_t contrast_store(struct device *dev, 155 struct device_attribute *attr, const char *buf, size_t count) 156 { 157 int rc; 158 struct lcd_device *ld = to_lcd_device(dev); 159 unsigned long contrast; 160 161 rc = kstrtoul(buf, 0, &contrast); 162 if (rc) 163 return rc; 164 165 rc = -ENXIO; 166 167 mutex_lock(&ld->ops_lock); 168 if (ld->ops && ld->ops->set_contrast) { 169 pr_debug("set contrast to %lu\n", contrast); 170 ld->ops->set_contrast(ld, contrast); 171 rc = count; 172 } 173 mutex_unlock(&ld->ops_lock); 174 175 return rc; 176 } 177 static DEVICE_ATTR_RW(contrast); 178 179 static ssize_t max_contrast_show(struct device *dev, 180 struct device_attribute *attr, char *buf) 181 { 182 struct lcd_device *ld = to_lcd_device(dev); 183 184 return sprintf(buf, "%d\n", ld->props.max_contrast); 185 } 186 static DEVICE_ATTR_RO(max_contrast); 187 188 static void lcd_device_release(struct device *dev) 189 { 190 struct lcd_device *ld = to_lcd_device(dev); 191 kfree(ld); 192 } 193 194 static struct attribute *lcd_device_attrs[] = { 195 &dev_attr_lcd_power.attr, 196 &dev_attr_contrast.attr, 197 &dev_attr_max_contrast.attr, 198 NULL, 199 }; 200 ATTRIBUTE_GROUPS(lcd_device); 201 202 static const struct class lcd_class = { 203 .name = "lcd", 204 .dev_groups = lcd_device_groups, 205 }; 206 207 /** 208 * lcd_device_register - register a new object of lcd_device class. 209 * @name: the name of the new object(must be the same as the name of the 210 * respective framebuffer device). 211 * @parent: pointer to the parent's struct device . 212 * @devdata: an optional pointer to be stored in the device. The 213 * methods may retrieve it by using lcd_get_data(ld). 214 * @ops: the lcd operations structure. 215 * 216 * Creates and registers a new lcd device. Returns either an ERR_PTR() 217 * or a pointer to the newly allocated device. 218 */ 219 struct lcd_device *lcd_device_register(const char *name, struct device *parent, 220 void *devdata, const struct lcd_ops *ops) 221 { 222 struct lcd_device *new_ld; 223 int rc; 224 225 pr_debug("lcd_device_register: name=%s\n", name); 226 227 new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL); 228 if (!new_ld) 229 return ERR_PTR(-ENOMEM); 230 231 mutex_init(&new_ld->ops_lock); 232 mutex_init(&new_ld->update_lock); 233 234 new_ld->dev.class = &lcd_class; 235 new_ld->dev.parent = parent; 236 new_ld->dev.release = lcd_device_release; 237 dev_set_name(&new_ld->dev, "%s", name); 238 dev_set_drvdata(&new_ld->dev, devdata); 239 240 new_ld->ops = ops; 241 242 rc = device_register(&new_ld->dev); 243 if (rc) { 244 put_device(&new_ld->dev); 245 return ERR_PTR(rc); 246 } 247 248 rc = lcd_register_fb(new_ld); 249 if (rc) { 250 device_unregister(&new_ld->dev); 251 return ERR_PTR(rc); 252 } 253 254 return new_ld; 255 } 256 EXPORT_SYMBOL(lcd_device_register); 257 258 /** 259 * lcd_device_unregister - unregisters a object of lcd_device class. 260 * @ld: the lcd device object to be unregistered and freed. 261 * 262 * Unregisters a previously registered via lcd_device_register object. 263 */ 264 void lcd_device_unregister(struct lcd_device *ld) 265 { 266 if (!ld) 267 return; 268 269 mutex_lock(&ld->ops_lock); 270 ld->ops = NULL; 271 mutex_unlock(&ld->ops_lock); 272 lcd_unregister_fb(ld); 273 274 device_unregister(&ld->dev); 275 } 276 EXPORT_SYMBOL(lcd_device_unregister); 277 278 static void devm_lcd_device_release(struct device *dev, void *res) 279 { 280 struct lcd_device *lcd = *(struct lcd_device **)res; 281 282 lcd_device_unregister(lcd); 283 } 284 285 static int devm_lcd_device_match(struct device *dev, void *res, void *data) 286 { 287 struct lcd_device **r = res; 288 289 return *r == data; 290 } 291 292 /** 293 * devm_lcd_device_register - resource managed lcd_device_register() 294 * @dev: the device to register 295 * @name: the name of the device 296 * @parent: a pointer to the parent device 297 * @devdata: an optional pointer to be stored for private driver use 298 * @ops: the lcd operations structure 299 * 300 * @return a struct lcd on success, or an ERR_PTR on error 301 * 302 * Managed lcd_device_register(). The lcd_device returned from this function 303 * are automatically freed on driver detach. See lcd_device_register() 304 * for more information. 305 */ 306 struct lcd_device *devm_lcd_device_register(struct device *dev, 307 const char *name, struct device *parent, 308 void *devdata, const struct lcd_ops *ops) 309 { 310 struct lcd_device **ptr, *lcd; 311 312 ptr = devres_alloc(devm_lcd_device_release, sizeof(*ptr), GFP_KERNEL); 313 if (!ptr) 314 return ERR_PTR(-ENOMEM); 315 316 lcd = lcd_device_register(name, parent, devdata, ops); 317 if (!IS_ERR(lcd)) { 318 *ptr = lcd; 319 devres_add(dev, ptr); 320 } else { 321 devres_free(ptr); 322 } 323 324 return lcd; 325 } 326 EXPORT_SYMBOL(devm_lcd_device_register); 327 328 /** 329 * devm_lcd_device_unregister - resource managed lcd_device_unregister() 330 * @dev: the device to unregister 331 * @ld: the lcd device to unregister 332 * 333 * Deallocated a lcd allocated with devm_lcd_device_register(). Normally 334 * this function will not need to be called and the resource management 335 * code will ensure that the resource is freed. 336 */ 337 void devm_lcd_device_unregister(struct device *dev, struct lcd_device *ld) 338 { 339 int rc; 340 341 rc = devres_release(dev, devm_lcd_device_release, 342 devm_lcd_device_match, ld); 343 WARN_ON(rc); 344 } 345 EXPORT_SYMBOL(devm_lcd_device_unregister); 346 347 348 static void __exit lcd_class_exit(void) 349 { 350 class_unregister(&lcd_class); 351 } 352 353 static int __init lcd_class_init(void) 354 { 355 int ret; 356 357 ret = class_register(&lcd_class); 358 if (ret) { 359 pr_warn("Unable to create backlight class; errno = %d\n", ret); 360 return ret; 361 } 362 363 return 0; 364 } 365 366 /* 367 * if this is compiled into the kernel, we need to ensure that the 368 * class is registered before users of the class try to register lcd's 369 */ 370 postcore_initcall(lcd_class_init); 371 module_exit(lcd_class_exit); 372 373 MODULE_LICENSE("GPL"); 374 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>"); 375 MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction"); 376