drivers/video/backlight/lcd.c

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