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