drivers/rtc/class.c

   1 /*
   2  * RTC subsystem, base class
   3  *
   4  * Copyright (C) 2005 Tower Technologies
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   6  *
   7  * class skeleton from drivers/hwmon/hwmon.c
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12 */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/rtc.h>
  19 #include <linux/kdev_t.h>
  20 #include <linux/idr.h>
  21 #include <linux/slab.h>
  22 #include <linux/workqueue.h>
  23
  24 #include "rtc-core.h"
  25
  26
  27 static DEFINE_IDA(rtc_ida);
  28 struct class *rtc_class;
  29
  30 static void rtc_device_release(struct device *dev)
  31 {
  32         struct rtc_device *rtc = to_rtc_device(dev);
  33         ida_simple_remove(&rtc_ida, rtc->id);
  34         kfree(rtc);
  35 }
  36
  37 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
  38 /* Result of the last RTC to system clock attempt. */
  39 int rtc_hctosys_ret = -ENODEV;
  40 #endif
  41
  42 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
  43 /*
  44  * On suspend(), measure the delta between one RTC and the
  45  * system's wall clock; restore it on resume().
  46  */
  47
  48 static struct timespec64 old_rtc, old_system, old_delta;
  49
  50
  51 static int rtc_suspend(struct device *dev)
  52 {
  53         struct rtc_device       *rtc = to_rtc_device(dev);
  54         struct rtc_time         tm;
  55         struct timespec64       delta, delta_delta;
  56         int err;
  57
  58         if (timekeeping_rtc_skipsuspend())
  59                 return 0;
  60
  61         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  62                 return 0;
  63
  64         /* snapshot the current RTC and system time at suspend*/
  65         err = rtc_read_time(rtc, &tm);
  66         if (err < 0) {
  67                 pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
  68                 return 0;
  69         }
  70
  71         getnstimeofday64(&old_system);
  72         old_rtc.tv_sec = rtc_tm_to_time64(&tm);
  73
  74
  75         /*
  76          * To avoid drift caused by repeated suspend/resumes,
  77          * which each can add ~1 second drift error,
  78          * try to compensate so the difference in system time
  79          * and rtc time stays close to constant.
  80          */
  81         delta = timespec64_sub(old_system, old_rtc);
  82         delta_delta = timespec64_sub(delta, old_delta);
  83         if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
  84                 /*
  85                  * if delta_delta is too large, assume time correction
  86                  * has occured and set old_delta to the current delta.
  87                  */
  88                 old_delta = delta;
  89         } else {
  90                 /* Otherwise try to adjust old_system to compensate */
  91                 old_system = timespec64_sub(old_system, delta_delta);
  92         }
  93
  94         return 0;
  95 }
  96
  97 static int rtc_resume(struct device *dev)
  98 {
  99         struct rtc_device       *rtc = to_rtc_device(dev);
 100         struct rtc_time         tm;
 101         struct timespec64       new_system, new_rtc;
 102         struct timespec64       sleep_time;
 103         int err;
 104
 105         if (timekeeping_rtc_skipresume())
 106                 return 0;
 107
 108         rtc_hctosys_ret = -ENODEV;
 109         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
 110                 return 0;
 111
 112         /* snapshot the current rtc and system time at resume */
 113         getnstimeofday64(&new_system);
 114         err = rtc_read_time(rtc, &tm);
 115         if (err < 0) {
 116                 pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
 117                 return 0;
 118         }
 119
 120         new_rtc.tv_sec = rtc_tm_to_time64(&tm);
 121         new_rtc.tv_nsec = 0;
 122
 123         if (new_rtc.tv_sec < old_rtc.tv_sec) {
 124                 pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 125                 return 0;
 126         }
 127
 128         /* calculate the RTC time delta (sleep time)*/
 129         sleep_time = timespec64_sub(new_rtc, old_rtc);
 130
 131         /*
 132          * Since these RTC suspend/resume handlers are not called
 133          * at the very end of suspend or the start of resume,
 134          * some run-time may pass on either sides of the sleep time
 135          * so subtract kernel run-time between rtc_suspend to rtc_resume
 136          * to keep things accurate.
 137          */
 138         sleep_time = timespec64_sub(sleep_time,
 139                         timespec64_sub(new_system, old_system));
 140
 141         if (sleep_time.tv_sec >= 0)
 142                 timekeeping_inject_sleeptime64(&sleep_time);
 143         rtc_hctosys_ret = 0;
 144         return 0;
 145 }
 146
 147 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
 148 #define RTC_CLASS_DEV_PM_OPS    (&rtc_class_dev_pm_ops)
 149 #else
 150 #define RTC_CLASS_DEV_PM_OPS    NULL
 151 #endif
 152
 153
 154 /**
 155  * rtc_device_register - register w/ RTC class
 156  * @dev: the device to register
 157  *
 158  * rtc_device_unregister() must be called when the class device is no
 159  * longer needed.
 160  *
 161  * Returns the pointer to the new struct class device.
 162  */
 163 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 164                                         const struct rtc_class_ops *ops,
 165                                         struct module *owner)
 166 {
 167         struct rtc_device *rtc;
 168         struct rtc_wkalrm alrm;
 169         int of_id = -1, id = -1, err;
 170
 171         if (dev->of_node)
 172                 of_id = of_alias_get_id(dev->of_node, "rtc");
 173         else if (dev->parent && dev->parent->of_node)
 174                 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
 175
 176         if (of_id >= 0) {
 177                 id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
 178                                     GFP_KERNEL);
 179                 if (id < 0)
 180                         dev_warn(dev, "/aliases ID %d not available\n",
 181                                     of_id);
 182         }
 183
 184         if (id < 0) {
 185                 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 186                 if (id < 0) {
 187                         err = id;
 188                         goto exit;
 189                 }
 190         }
 191
 192         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 193         if (rtc == NULL) {
 194                 err = -ENOMEM;
 195                 goto exit_ida;
 196         }
 197
 198         device_initialize(&rtc->dev);
 199
 200         rtc->id = id;
 201         rtc->ops = ops;
 202         rtc->owner = owner;
 203         rtc->irq_freq = 1;
 204         rtc->max_user_freq = 64;
 205         rtc->dev.parent = dev;
 206         rtc->dev.class = rtc_class;
 207         rtc->dev.groups = rtc_get_dev_attribute_groups();
 208         rtc->dev.release = rtc_device_release;
 209
 210         mutex_init(&rtc->ops_lock);
 211         spin_lock_init(&rtc->irq_lock);
 212         spin_lock_init(&rtc->irq_task_lock);
 213         init_waitqueue_head(&rtc->irq_queue);
 214
 215         /* Init timerqueue */
 216         timerqueue_init_head(&rtc->timerqueue);
 217         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 218         /* Init aie timer */
 219         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 220         /* Init uie timer */
 221         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 222         /* Init pie timer */
 223         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 224         rtc->pie_timer.function = rtc_pie_update_irq;
 225         rtc->pie_enabled = 0;
 226
 227         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 228         dev_set_name(&rtc->dev, "rtc%d", id);
 229
 230         /* Check to see if there is an ALARM already set in hw */
 231         err = __rtc_read_alarm(rtc, &alrm);
 232
 233         if (!err && !rtc_valid_tm(&alrm.time))
 234                 rtc_initialize_alarm(rtc, &alrm);
 235
 236         rtc_dev_prepare(rtc);
 237
 238         err = cdev_device_add(&rtc->char_dev, &rtc->dev);
 239         if (err) {
 240                 dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
 241                          rtc->name, MAJOR(rtc->dev.devt), rtc->id);
 242
 243                 /* This will free both memory and the ID */
 244                 put_device(&rtc->dev);
 245                 goto exit;
 246         } else {
 247                 dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", rtc->name,
 248                         MAJOR(rtc->dev.devt), rtc->id);
 249         }
 250
 251         rtc_proc_add_device(rtc);
 252
 253         dev_info(dev, "rtc core: registered %s as %s\n",
 254                         rtc->name, dev_name(&rtc->dev));
 255
 256         return rtc;
 257
 258 exit_ida:
 259         ida_simple_remove(&rtc_ida, id);
 260
 261 exit:
 262         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 263                         name, err);
 264         return ERR_PTR(err);
 265 }
 266 EXPORT_SYMBOL_GPL(rtc_device_register);
 267
 268
 269 /**
 270  * rtc_device_unregister - removes the previously registered RTC class device
 271  *
 272  * @rtc: the RTC class device to destroy
 273  */
 274 void rtc_device_unregister(struct rtc_device *rtc)
 275 {
 276         mutex_lock(&rtc->ops_lock);
 277         /*
 278          * Remove innards of this RTC, then disable it, before
 279          * letting any rtc_class_open() users access it again
 280          */
 281         rtc_proc_del_device(rtc);
 282         cdev_device_del(&rtc->char_dev, &rtc->dev);
 283         rtc->ops = NULL;
 284         mutex_unlock(&rtc->ops_lock);
 285         put_device(&rtc->dev);
 286 }
 287 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 288
 289 static void devm_rtc_device_release(struct device *dev, void *res)
 290 {
 291         struct rtc_device *rtc = *(struct rtc_device **)res;
 292
 293         rtc_device_unregister(rtc);
 294 }
 295
 296 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
 297 {
 298         struct rtc **r = res;
 299
 300         return *r == data;
 301 }
 302
 303 /**
 304  * devm_rtc_device_register - resource managed rtc_device_register()
 305  * @dev: the device to register
 306  * @name: the name of the device
 307  * @ops: the rtc operations structure
 308  * @owner: the module owner
 309  *
 310  * @return a struct rtc on success, or an ERR_PTR on error
 311  *
 312  * Managed rtc_device_register(). The rtc_device returned from this function
 313  * are automatically freed on driver detach. See rtc_device_register()
 314  * for more information.
 315  */
 316
 317 struct rtc_device *devm_rtc_device_register(struct device *dev,
 318                                         const char *name,
 319                                         const struct rtc_class_ops *ops,
 320                                         struct module *owner)
 321 {
 322         struct rtc_device **ptr, *rtc;
 323
 324         ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
 325         if (!ptr)
 326                 return ERR_PTR(-ENOMEM);
 327
 328         rtc = rtc_device_register(name, dev, ops, owner);
 329         if (!IS_ERR(rtc)) {
 330                 *ptr = rtc;
 331                 devres_add(dev, ptr);
 332         } else {
 333                 devres_free(ptr);
 334         }
 335
 336         return rtc;
 337 }
 338 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 339
 340 /**
 341  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 342  * @dev: the device to unregister
 343  * @rtc: the RTC class device to unregister
 344  *
 345  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 346  * function will not need to be called and the resource management code will
 347  * ensure that the resource is freed.
 348  */
 349 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
 350 {
 351         int rc;
 352
 353         rc = devres_release(dev, devm_rtc_device_release,
 354                                 devm_rtc_device_match, rtc);
 355         WARN_ON(rc);
 356 }
 357 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
 358
 359 static int __init rtc_init(void)
 360 {
 361         rtc_class = class_create(THIS_MODULE, "rtc");
 362         if (IS_ERR(rtc_class)) {
 363                 pr_err("couldn't create class\n");
 364                 return PTR_ERR(rtc_class);
 365         }
 366         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 367         rtc_dev_init();
 368         return 0;
 369 }
 370 subsys_initcall(rtc_init);