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 timespec 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 timespec delta, delta_delta; 56 57 if (has_persistent_clock()) 58 return 0; 59 60 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 61 return 0; 62 63 /* snapshot the current RTC and system time at suspend*/ 64 rtc_read_time(rtc, &tm); 65 getnstimeofday(&old_system); 66 rtc_tm_to_time(&tm, &old_rtc.tv_sec); 67 68 69 /* 70 * To avoid drift caused by repeated suspend/resumes, 71 * which each can add ~1 second drift error, 72 * try to compensate so the difference in system time 73 * and rtc time stays close to constant. 74 */ 75 delta = timespec_sub(old_system, old_rtc); 76 delta_delta = timespec_sub(delta, old_delta); 77 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) { 78 /* 79 * if delta_delta is too large, assume time correction 80 * has occured and set old_delta to the current delta. 81 */ 82 old_delta = delta; 83 } else { 84 /* Otherwise try to adjust old_system to compensate */ 85 old_system = timespec_sub(old_system, delta_delta); 86 } 87 88 return 0; 89 } 90 91 static int rtc_resume(struct device *dev) 92 { 93 struct rtc_device *rtc = to_rtc_device(dev); 94 struct rtc_time tm; 95 struct timespec new_system, new_rtc; 96 struct timespec sleep_time; 97 98 if (has_persistent_clock()) 99 return 0; 100 101 rtc_hctosys_ret = -ENODEV; 102 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 103 return 0; 104 105 /* snapshot the current rtc and system time at resume */ 106 getnstimeofday(&new_system); 107 rtc_read_time(rtc, &tm); 108 if (rtc_valid_tm(&tm) != 0) { 109 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev)); 110 return 0; 111 } 112 rtc_tm_to_time(&tm, &new_rtc.tv_sec); 113 new_rtc.tv_nsec = 0; 114 115 if (new_rtc.tv_sec < old_rtc.tv_sec) { 116 pr_debug("%s: time travel!\n", dev_name(&rtc->dev)); 117 return 0; 118 } 119 120 /* calculate the RTC time delta (sleep time)*/ 121 sleep_time = timespec_sub(new_rtc, old_rtc); 122 123 /* 124 * Since these RTC suspend/resume handlers are not called 125 * at the very end of suspend or the start of resume, 126 * some run-time may pass on either sides of the sleep time 127 * so subtract kernel run-time between rtc_suspend to rtc_resume 128 * to keep things accurate. 129 */ 130 sleep_time = timespec_sub(sleep_time, 131 timespec_sub(new_system, old_system)); 132 133 if (sleep_time.tv_sec >= 0) 134 timekeeping_inject_sleeptime(&sleep_time); 135 rtc_hctosys_ret = 0; 136 return 0; 137 } 138 139 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume); 140 #define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops) 141 #else 142 #define RTC_CLASS_DEV_PM_OPS NULL 143 #endif 144 145 146 /** 147 * rtc_device_register - register w/ RTC class 148 * @dev: the device to register 149 * 150 * rtc_device_unregister() must be called when the class device is no 151 * longer needed. 152 * 153 * Returns the pointer to the new struct class device. 154 */ 155 struct rtc_device *rtc_device_register(const char *name, struct device *dev, 156 const struct rtc_class_ops *ops, 157 struct module *owner) 158 { 159 struct rtc_device *rtc; 160 struct rtc_wkalrm alrm; 161 int of_id = -1, id = -1, err; 162 163 if (dev->of_node) 164 of_id = of_alias_get_id(dev->of_node, "rtc"); 165 else if (dev->parent && dev->parent->of_node) 166 of_id = of_alias_get_id(dev->parent->of_node, "rtc"); 167 168 if (of_id >= 0) { 169 id = ida_simple_get(&rtc_ida, of_id, of_id + 1, 170 GFP_KERNEL); 171 if (id < 0) 172 dev_warn(dev, "/aliases ID %d not available\n", 173 of_id); 174 } 175 176 if (id < 0) { 177 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL); 178 if (id < 0) { 179 err = id; 180 goto exit; 181 } 182 } 183 184 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL); 185 if (rtc == NULL) { 186 err = -ENOMEM; 187 goto exit_ida; 188 } 189 190 rtc->id = id; 191 rtc->ops = ops; 192 rtc->owner = owner; 193 rtc->irq_freq = 1; 194 rtc->max_user_freq = 64; 195 rtc->dev.parent = dev; 196 rtc->dev.class = rtc_class; 197 rtc->dev.release = rtc_device_release; 198 199 mutex_init(&rtc->ops_lock); 200 spin_lock_init(&rtc->irq_lock); 201 spin_lock_init(&rtc->irq_task_lock); 202 init_waitqueue_head(&rtc->irq_queue); 203 204 /* Init timerqueue */ 205 timerqueue_init_head(&rtc->timerqueue); 206 INIT_WORK(&rtc->irqwork, rtc_timer_do_work); 207 /* Init aie timer */ 208 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc); 209 /* Init uie timer */ 210 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc); 211 /* Init pie timer */ 212 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 213 rtc->pie_timer.function = rtc_pie_update_irq; 214 rtc->pie_enabled = 0; 215 216 /* Check to see if there is an ALARM already set in hw */ 217 err = __rtc_read_alarm(rtc, &alrm); 218 219 if (!err && !rtc_valid_tm(&alrm.time)) 220 rtc_initialize_alarm(rtc, &alrm); 221 222 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 223 dev_set_name(&rtc->dev, "rtc%d", id); 224 225 rtc_dev_prepare(rtc); 226 227 err = device_register(&rtc->dev); 228 if (err) { 229 put_device(&rtc->dev); 230 goto exit_kfree; 231 } 232 233 rtc_dev_add_device(rtc); 234 rtc_sysfs_add_device(rtc); 235 rtc_proc_add_device(rtc); 236 237 dev_info(dev, "rtc core: registered %s as %s\n", 238 rtc->name, dev_name(&rtc->dev)); 239 240 return rtc; 241 242 exit_kfree: 243 kfree(rtc); 244 245 exit_ida: 246 ida_simple_remove(&rtc_ida, id); 247 248 exit: 249 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 250 name, err); 251 return ERR_PTR(err); 252 } 253 EXPORT_SYMBOL_GPL(rtc_device_register); 254 255 256 /** 257 * rtc_device_unregister - removes the previously registered RTC class device 258 * 259 * @rtc: the RTC class device to destroy 260 */ 261 void rtc_device_unregister(struct rtc_device *rtc) 262 { 263 if (get_device(&rtc->dev) != NULL) { 264 mutex_lock(&rtc->ops_lock); 265 /* remove innards of this RTC, then disable it, before 266 * letting any rtc_class_open() users access it again 267 */ 268 rtc_sysfs_del_device(rtc); 269 rtc_dev_del_device(rtc); 270 rtc_proc_del_device(rtc); 271 device_unregister(&rtc->dev); 272 rtc->ops = NULL; 273 mutex_unlock(&rtc->ops_lock); 274 put_device(&rtc->dev); 275 } 276 } 277 EXPORT_SYMBOL_GPL(rtc_device_unregister); 278 279 static void devm_rtc_device_release(struct device *dev, void *res) 280 { 281 struct rtc_device *rtc = *(struct rtc_device **)res; 282 283 rtc_device_unregister(rtc); 284 } 285 286 static int devm_rtc_device_match(struct device *dev, void *res, void *data) 287 { 288 struct rtc **r = res; 289 290 return *r == data; 291 } 292 293 /** 294 * devm_rtc_device_register - resource managed rtc_device_register() 295 * @dev: the device to register 296 * @name: the name of the device 297 * @ops: the rtc operations structure 298 * @owner: the module owner 299 * 300 * @return a struct rtc on success, or an ERR_PTR on error 301 * 302 * Managed rtc_device_register(). The rtc_device returned from this function 303 * are automatically freed on driver detach. See rtc_device_register() 304 * for more information. 305 */ 306 307 struct rtc_device *devm_rtc_device_register(struct device *dev, 308 const char *name, 309 const struct rtc_class_ops *ops, 310 struct module *owner) 311 { 312 struct rtc_device **ptr, *rtc; 313 314 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL); 315 if (!ptr) 316 return ERR_PTR(-ENOMEM); 317 318 rtc = rtc_device_register(name, dev, ops, owner); 319 if (!IS_ERR(rtc)) { 320 *ptr = rtc; 321 devres_add(dev, ptr); 322 } else { 323 devres_free(ptr); 324 } 325 326 return rtc; 327 } 328 EXPORT_SYMBOL_GPL(devm_rtc_device_register); 329 330 /** 331 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister() 332 * @dev: the device to unregister 333 * @rtc: the RTC class device to unregister 334 * 335 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this 336 * function will not need to be called and the resource management code will 337 * ensure that the resource is freed. 338 */ 339 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc) 340 { 341 int rc; 342 343 rc = devres_release(dev, devm_rtc_device_release, 344 devm_rtc_device_match, rtc); 345 WARN_ON(rc); 346 } 347 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister); 348 349 static int __init rtc_init(void) 350 { 351 rtc_class = class_create(THIS_MODULE, "rtc"); 352 if (IS_ERR(rtc_class)) { 353 pr_err("couldn't create class\n"); 354 return PTR_ERR(rtc_class); 355 } 356 rtc_class->pm = RTC_CLASS_DEV_PM_OPS; 357 rtc_dev_init(); 358 rtc_sysfs_init(rtc_class); 359 return 0; 360 } 361 362 static void __exit rtc_exit(void) 363 { 364 rtc_dev_exit(); 365 class_destroy(rtc_class); 366 ida_destroy(&rtc_ida); 367 } 368 369 subsys_initcall(rtc_init); 370 module_exit(rtc_exit); 371 372 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 373 MODULE_DESCRIPTION("RTC class support"); 374 MODULE_LICENSE("GPL"); 375