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