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