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 (has_persistent_clock()) 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 (has_persistent_clock()) 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 if (rtc_valid_tm(&tm) != 0) { 121 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev)); 122 return 0; 123 } 124 new_rtc.tv_sec = rtc_tm_to_time64(&tm); 125 new_rtc.tv_nsec = 0; 126 127 if (new_rtc.tv_sec < old_rtc.tv_sec) { 128 pr_debug("%s: time travel!\n", dev_name(&rtc->dev)); 129 return 0; 130 } 131 132 /* calculate the RTC time delta (sleep time)*/ 133 sleep_time = timespec64_sub(new_rtc, old_rtc); 134 135 /* 136 * Since these RTC suspend/resume handlers are not called 137 * at the very end of suspend or the start of resume, 138 * some run-time may pass on either sides of the sleep time 139 * so subtract kernel run-time between rtc_suspend to rtc_resume 140 * to keep things accurate. 141 */ 142 sleep_time = timespec64_sub(sleep_time, 143 timespec64_sub(new_system, old_system)); 144 145 if (sleep_time.tv_sec >= 0) 146 timekeeping_inject_sleeptime64(&sleep_time); 147 rtc_hctosys_ret = 0; 148 return 0; 149 } 150 151 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume); 152 #define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops) 153 #else 154 #define RTC_CLASS_DEV_PM_OPS NULL 155 #endif 156 157 158 /** 159 * rtc_device_register - register w/ RTC class 160 * @dev: the device to register 161 * 162 * rtc_device_unregister() must be called when the class device is no 163 * longer needed. 164 * 165 * Returns the pointer to the new struct class device. 166 */ 167 struct rtc_device *rtc_device_register(const char *name, struct device *dev, 168 const struct rtc_class_ops *ops, 169 struct module *owner) 170 { 171 struct rtc_device *rtc; 172 struct rtc_wkalrm alrm; 173 int of_id = -1, id = -1, err; 174 175 if (dev->of_node) 176 of_id = of_alias_get_id(dev->of_node, "rtc"); 177 else if (dev->parent && dev->parent->of_node) 178 of_id = of_alias_get_id(dev->parent->of_node, "rtc"); 179 180 if (of_id >= 0) { 181 id = ida_simple_get(&rtc_ida, of_id, of_id + 1, 182 GFP_KERNEL); 183 if (id < 0) 184 dev_warn(dev, "/aliases ID %d not available\n", 185 of_id); 186 } 187 188 if (id < 0) { 189 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL); 190 if (id < 0) { 191 err = id; 192 goto exit; 193 } 194 } 195 196 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL); 197 if (rtc == NULL) { 198 err = -ENOMEM; 199 goto exit_ida; 200 } 201 202 rtc->id = id; 203 rtc->ops = ops; 204 rtc->owner = owner; 205 rtc->irq_freq = 1; 206 rtc->max_user_freq = 64; 207 rtc->dev.parent = dev; 208 rtc->dev.class = rtc_class; 209 rtc->dev.release = rtc_device_release; 210 211 mutex_init(&rtc->ops_lock); 212 spin_lock_init(&rtc->irq_lock); 213 spin_lock_init(&rtc->irq_task_lock); 214 init_waitqueue_head(&rtc->irq_queue); 215 216 /* Init timerqueue */ 217 timerqueue_init_head(&rtc->timerqueue); 218 INIT_WORK(&rtc->irqwork, rtc_timer_do_work); 219 /* Init aie timer */ 220 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc); 221 /* Init uie timer */ 222 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc); 223 /* Init pie timer */ 224 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 225 rtc->pie_timer.function = rtc_pie_update_irq; 226 rtc->pie_enabled = 0; 227 228 /* Check to see if there is an ALARM already set in hw */ 229 err = __rtc_read_alarm(rtc, &alrm); 230 231 if (!err && !rtc_valid_tm(&alrm.time)) 232 rtc_initialize_alarm(rtc, &alrm); 233 234 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 235 dev_set_name(&rtc->dev, "rtc%d", id); 236 237 rtc_dev_prepare(rtc); 238 239 err = device_register(&rtc->dev); 240 if (err) { 241 put_device(&rtc->dev); 242 goto exit_kfree; 243 } 244 245 rtc_dev_add_device(rtc); 246 rtc_sysfs_add_device(rtc); 247 rtc_proc_add_device(rtc); 248 249 dev_info(dev, "rtc core: registered %s as %s\n", 250 rtc->name, dev_name(&rtc->dev)); 251 252 return rtc; 253 254 exit_kfree: 255 kfree(rtc); 256 257 exit_ida: 258 ida_simple_remove(&rtc_ida, id); 259 260 exit: 261 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 262 name, err); 263 return ERR_PTR(err); 264 } 265 EXPORT_SYMBOL_GPL(rtc_device_register); 266 267 268 /** 269 * rtc_device_unregister - removes the previously registered RTC class device 270 * 271 * @rtc: the RTC class device to destroy 272 */ 273 void rtc_device_unregister(struct rtc_device *rtc) 274 { 275 if (get_device(&rtc->dev) != NULL) { 276 mutex_lock(&rtc->ops_lock); 277 /* remove innards of this RTC, then disable it, before 278 * letting any rtc_class_open() users access it again 279 */ 280 rtc_sysfs_del_device(rtc); 281 rtc_dev_del_device(rtc); 282 rtc_proc_del_device(rtc); 283 device_unregister(&rtc->dev); 284 rtc->ops = NULL; 285 mutex_unlock(&rtc->ops_lock); 286 put_device(&rtc->dev); 287 } 288 } 289 EXPORT_SYMBOL_GPL(rtc_device_unregister); 290 291 static void devm_rtc_device_release(struct device *dev, void *res) 292 { 293 struct rtc_device *rtc = *(struct rtc_device **)res; 294 295 rtc_device_unregister(rtc); 296 } 297 298 static int devm_rtc_device_match(struct device *dev, void *res, void *data) 299 { 300 struct rtc **r = res; 301 302 return *r == data; 303 } 304 305 /** 306 * devm_rtc_device_register - resource managed rtc_device_register() 307 * @dev: the device to register 308 * @name: the name of the device 309 * @ops: the rtc operations structure 310 * @owner: the module owner 311 * 312 * @return a struct rtc on success, or an ERR_PTR on error 313 * 314 * Managed rtc_device_register(). The rtc_device returned from this function 315 * are automatically freed on driver detach. See rtc_device_register() 316 * for more information. 317 */ 318 319 struct rtc_device *devm_rtc_device_register(struct device *dev, 320 const char *name, 321 const struct rtc_class_ops *ops, 322 struct module *owner) 323 { 324 struct rtc_device **ptr, *rtc; 325 326 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL); 327 if (!ptr) 328 return ERR_PTR(-ENOMEM); 329 330 rtc = rtc_device_register(name, dev, ops, owner); 331 if (!IS_ERR(rtc)) { 332 *ptr = rtc; 333 devres_add(dev, ptr); 334 } else { 335 devres_free(ptr); 336 } 337 338 return rtc; 339 } 340 EXPORT_SYMBOL_GPL(devm_rtc_device_register); 341 342 /** 343 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister() 344 * @dev: the device to unregister 345 * @rtc: the RTC class device to unregister 346 * 347 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this 348 * function will not need to be called and the resource management code will 349 * ensure that the resource is freed. 350 */ 351 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc) 352 { 353 int rc; 354 355 rc = devres_release(dev, devm_rtc_device_release, 356 devm_rtc_device_match, rtc); 357 WARN_ON(rc); 358 } 359 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister); 360 361 static int __init rtc_init(void) 362 { 363 rtc_class = class_create(THIS_MODULE, "rtc"); 364 if (IS_ERR(rtc_class)) { 365 pr_err("couldn't create class\n"); 366 return PTR_ERR(rtc_class); 367 } 368 rtc_class->pm = RTC_CLASS_DEV_PM_OPS; 369 rtc_dev_init(); 370 rtc_sysfs_init(rtc_class); 371 return 0; 372 } 373 374 static void __exit rtc_exit(void) 375 { 376 rtc_dev_exit(); 377 class_destroy(rtc_class); 378 ida_destroy(&rtc_ida); 379 } 380 381 subsys_initcall(rtc_init); 382 module_exit(rtc_exit); 383 384 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 385 MODULE_DESCRIPTION("RTC class support"); 386 MODULE_LICENSE("GPL"); 387