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 rtc->id = id; 199 rtc->ops = ops; 200 rtc->owner = owner; 201 rtc->irq_freq = 1; 202 rtc->max_user_freq = 64; 203 rtc->dev.parent = dev; 204 rtc->dev.class = rtc_class; 205 rtc->dev.release = rtc_device_release; 206 207 mutex_init(&rtc->ops_lock); 208 spin_lock_init(&rtc->irq_lock); 209 spin_lock_init(&rtc->irq_task_lock); 210 init_waitqueue_head(&rtc->irq_queue); 211 212 /* Init timerqueue */ 213 timerqueue_init_head(&rtc->timerqueue); 214 INIT_WORK(&rtc->irqwork, rtc_timer_do_work); 215 /* Init aie timer */ 216 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc); 217 /* Init uie timer */ 218 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc); 219 /* Init pie timer */ 220 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 221 rtc->pie_timer.function = rtc_pie_update_irq; 222 rtc->pie_enabled = 0; 223 224 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 225 dev_set_name(&rtc->dev, "rtc%d", id); 226 227 /* Check to see if there is an ALARM already set in hw */ 228 err = __rtc_read_alarm(rtc, &alrm); 229 230 if (!err && !rtc_valid_tm(&alrm.time)) 231 rtc_initialize_alarm(rtc, &alrm); 232 233 rtc_dev_prepare(rtc); 234 235 err = device_register(&rtc->dev); 236 if (err) { 237 put_device(&rtc->dev); 238 goto exit_kfree; 239 } 240 241 rtc_dev_add_device(rtc); 242 rtc_sysfs_add_device(rtc); 243 rtc_proc_add_device(rtc); 244 245 dev_info(dev, "rtc core: registered %s as %s\n", 246 rtc->name, dev_name(&rtc->dev)); 247 248 return rtc; 249 250 exit_kfree: 251 kfree(rtc); 252 253 exit_ida: 254 ida_simple_remove(&rtc_ida, id); 255 256 exit: 257 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 258 name, err); 259 return ERR_PTR(err); 260 } 261 EXPORT_SYMBOL_GPL(rtc_device_register); 262 263 264 /** 265 * rtc_device_unregister - removes the previously registered RTC class device 266 * 267 * @rtc: the RTC class device to destroy 268 */ 269 void rtc_device_unregister(struct rtc_device *rtc) 270 { 271 if (get_device(&rtc->dev) != NULL) { 272 mutex_lock(&rtc->ops_lock); 273 /* remove innards of this RTC, then disable it, before 274 * letting any rtc_class_open() users access it again 275 */ 276 rtc_sysfs_del_device(rtc); 277 rtc_dev_del_device(rtc); 278 rtc_proc_del_device(rtc); 279 device_unregister(&rtc->dev); 280 rtc->ops = NULL; 281 mutex_unlock(&rtc->ops_lock); 282 put_device(&rtc->dev); 283 } 284 } 285 EXPORT_SYMBOL_GPL(rtc_device_unregister); 286 287 static void devm_rtc_device_release(struct device *dev, void *res) 288 { 289 struct rtc_device *rtc = *(struct rtc_device **)res; 290 291 rtc_device_unregister(rtc); 292 } 293 294 static int devm_rtc_device_match(struct device *dev, void *res, void *data) 295 { 296 struct rtc **r = res; 297 298 return *r == data; 299 } 300 301 /** 302 * devm_rtc_device_register - resource managed rtc_device_register() 303 * @dev: the device to register 304 * @name: the name of the device 305 * @ops: the rtc operations structure 306 * @owner: the module owner 307 * 308 * @return a struct rtc on success, or an ERR_PTR on error 309 * 310 * Managed rtc_device_register(). The rtc_device returned from this function 311 * are automatically freed on driver detach. See rtc_device_register() 312 * for more information. 313 */ 314 315 struct rtc_device *devm_rtc_device_register(struct device *dev, 316 const char *name, 317 const struct rtc_class_ops *ops, 318 struct module *owner) 319 { 320 struct rtc_device **ptr, *rtc; 321 322 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL); 323 if (!ptr) 324 return ERR_PTR(-ENOMEM); 325 326 rtc = rtc_device_register(name, dev, ops, owner); 327 if (!IS_ERR(rtc)) { 328 *ptr = rtc; 329 devres_add(dev, ptr); 330 } else { 331 devres_free(ptr); 332 } 333 334 return rtc; 335 } 336 EXPORT_SYMBOL_GPL(devm_rtc_device_register); 337 338 /** 339 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister() 340 * @dev: the device to unregister 341 * @rtc: the RTC class device to unregister 342 * 343 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this 344 * function will not need to be called and the resource management code will 345 * ensure that the resource is freed. 346 */ 347 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc) 348 { 349 int rc; 350 351 rc = devres_release(dev, devm_rtc_device_release, 352 devm_rtc_device_match, rtc); 353 WARN_ON(rc); 354 } 355 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister); 356 357 static int __init rtc_init(void) 358 { 359 rtc_class = class_create(THIS_MODULE, "rtc"); 360 if (IS_ERR(rtc_class)) { 361 pr_err("couldn't create class\n"); 362 return PTR_ERR(rtc_class); 363 } 364 rtc_class->pm = RTC_CLASS_DEV_PM_OPS; 365 rtc_dev_init(); 366 rtc_sysfs_init(rtc_class); 367 return 0; 368 } 369 370 static void __exit rtc_exit(void) 371 { 372 rtc_dev_exit(); 373 class_destroy(rtc_class); 374 ida_destroy(&rtc_ida); 375 } 376 377 subsys_initcall(rtc_init); 378 module_exit(rtc_exit); 379 380 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 381 MODULE_DESCRIPTION("RTC class support"); 382 MODULE_LICENSE("GPL"); 383