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 #include <linux/module.h> 15 #include <linux/rtc.h> 16 #include <linux/kdev_t.h> 17 #include <linux/idr.h> 18 #include <linux/slab.h> 19 #include <linux/workqueue.h> 20 21 #include "rtc-core.h" 22 23 24 static DEFINE_IDA(rtc_ida); 25 struct class *rtc_class; 26 27 static void rtc_device_release(struct device *dev) 28 { 29 struct rtc_device *rtc = to_rtc_device(dev); 30 ida_simple_remove(&rtc_ida, rtc->id); 31 kfree(rtc); 32 } 33 34 #ifdef CONFIG_RTC_HCTOSYS_DEVICE 35 /* Result of the last RTC to system clock attempt. */ 36 int rtc_hctosys_ret = -ENODEV; 37 #endif 38 39 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE) 40 /* 41 * On suspend(), measure the delta between one RTC and the 42 * system's wall clock; restore it on resume(). 43 */ 44 45 static struct timespec old_rtc, old_system, old_delta; 46 47 48 static int rtc_suspend(struct device *dev, pm_message_t mesg) 49 { 50 struct rtc_device *rtc = to_rtc_device(dev); 51 struct rtc_time tm; 52 struct timespec delta, delta_delta; 53 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 54 return 0; 55 56 /* snapshot the current RTC and system time at suspend*/ 57 rtc_read_time(rtc, &tm); 58 getnstimeofday(&old_system); 59 rtc_tm_to_time(&tm, &old_rtc.tv_sec); 60 61 62 /* 63 * To avoid drift caused by repeated suspend/resumes, 64 * which each can add ~1 second drift error, 65 * try to compensate so the difference in system time 66 * and rtc time stays close to constant. 67 */ 68 delta = timespec_sub(old_system, old_rtc); 69 delta_delta = timespec_sub(delta, old_delta); 70 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) { 71 /* 72 * if delta_delta is too large, assume time correction 73 * has occured and set old_delta to the current delta. 74 */ 75 old_delta = delta; 76 } else { 77 /* Otherwise try to adjust old_system to compensate */ 78 old_system = timespec_sub(old_system, delta_delta); 79 } 80 81 return 0; 82 } 83 84 static int rtc_resume(struct device *dev) 85 { 86 struct rtc_device *rtc = to_rtc_device(dev); 87 struct rtc_time tm; 88 struct timespec new_system, new_rtc; 89 struct timespec sleep_time; 90 91 rtc_hctosys_ret = -ENODEV; 92 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 93 return 0; 94 95 /* snapshot the current rtc and system time at resume */ 96 getnstimeofday(&new_system); 97 rtc_read_time(rtc, &tm); 98 if (rtc_valid_tm(&tm) != 0) { 99 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev)); 100 return 0; 101 } 102 rtc_tm_to_time(&tm, &new_rtc.tv_sec); 103 new_rtc.tv_nsec = 0; 104 105 if (new_rtc.tv_sec < old_rtc.tv_sec) { 106 pr_debug("%s: time travel!\n", dev_name(&rtc->dev)); 107 return 0; 108 } 109 110 /* calculate the RTC time delta (sleep time)*/ 111 sleep_time = timespec_sub(new_rtc, old_rtc); 112 113 /* 114 * Since these RTC suspend/resume handlers are not called 115 * at the very end of suspend or the start of resume, 116 * some run-time may pass on either sides of the sleep time 117 * so subtract kernel run-time between rtc_suspend to rtc_resume 118 * to keep things accurate. 119 */ 120 sleep_time = timespec_sub(sleep_time, 121 timespec_sub(new_system, old_system)); 122 123 if (sleep_time.tv_sec >= 0) 124 timekeeping_inject_sleeptime(&sleep_time); 125 rtc_hctosys_ret = 0; 126 return 0; 127 } 128 129 #else 130 #define rtc_suspend NULL 131 #define rtc_resume NULL 132 #endif 133 134 135 /** 136 * rtc_device_register - register w/ RTC class 137 * @dev: the device to register 138 * 139 * rtc_device_unregister() must be called when the class device is no 140 * longer needed. 141 * 142 * Returns the pointer to the new struct class device. 143 */ 144 struct rtc_device *rtc_device_register(const char *name, struct device *dev, 145 const struct rtc_class_ops *ops, 146 struct module *owner) 147 { 148 struct rtc_device *rtc; 149 struct rtc_wkalrm alrm; 150 int id, err; 151 152 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL); 153 if (id < 0) { 154 err = id; 155 goto exit; 156 } 157 158 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL); 159 if (rtc == NULL) { 160 err = -ENOMEM; 161 goto exit_ida; 162 } 163 164 rtc->id = id; 165 rtc->ops = ops; 166 rtc->owner = owner; 167 rtc->irq_freq = 1; 168 rtc->max_user_freq = 64; 169 rtc->dev.parent = dev; 170 rtc->dev.class = rtc_class; 171 rtc->dev.release = rtc_device_release; 172 173 mutex_init(&rtc->ops_lock); 174 spin_lock_init(&rtc->irq_lock); 175 spin_lock_init(&rtc->irq_task_lock); 176 init_waitqueue_head(&rtc->irq_queue); 177 178 /* Init timerqueue */ 179 timerqueue_init_head(&rtc->timerqueue); 180 INIT_WORK(&rtc->irqwork, rtc_timer_do_work); 181 /* Init aie timer */ 182 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc); 183 /* Init uie timer */ 184 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc); 185 /* Init pie timer */ 186 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 187 rtc->pie_timer.function = rtc_pie_update_irq; 188 rtc->pie_enabled = 0; 189 190 /* Check to see if there is an ALARM already set in hw */ 191 err = __rtc_read_alarm(rtc, &alrm); 192 193 if (!err && !rtc_valid_tm(&alrm.time)) 194 rtc_initialize_alarm(rtc, &alrm); 195 196 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 197 dev_set_name(&rtc->dev, "rtc%d", id); 198 199 rtc_dev_prepare(rtc); 200 201 err = device_register(&rtc->dev); 202 if (err) { 203 put_device(&rtc->dev); 204 goto exit_kfree; 205 } 206 207 rtc_dev_add_device(rtc); 208 rtc_sysfs_add_device(rtc); 209 rtc_proc_add_device(rtc); 210 211 dev_info(dev, "rtc core: registered %s as %s\n", 212 rtc->name, dev_name(&rtc->dev)); 213 214 return rtc; 215 216 exit_kfree: 217 kfree(rtc); 218 219 exit_ida: 220 ida_simple_remove(&rtc_ida, id); 221 222 exit: 223 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 224 name, err); 225 return ERR_PTR(err); 226 } 227 EXPORT_SYMBOL_GPL(rtc_device_register); 228 229 230 /** 231 * rtc_device_unregister - removes the previously registered RTC class device 232 * 233 * @rtc: the RTC class device to destroy 234 */ 235 void rtc_device_unregister(struct rtc_device *rtc) 236 { 237 if (get_device(&rtc->dev) != NULL) { 238 mutex_lock(&rtc->ops_lock); 239 /* remove innards of this RTC, then disable it, before 240 * letting any rtc_class_open() users access it again 241 */ 242 rtc_sysfs_del_device(rtc); 243 rtc_dev_del_device(rtc); 244 rtc_proc_del_device(rtc); 245 device_unregister(&rtc->dev); 246 rtc->ops = NULL; 247 mutex_unlock(&rtc->ops_lock); 248 put_device(&rtc->dev); 249 } 250 } 251 EXPORT_SYMBOL_GPL(rtc_device_unregister); 252 253 static int __init rtc_init(void) 254 { 255 rtc_class = class_create(THIS_MODULE, "rtc"); 256 if (IS_ERR(rtc_class)) { 257 printk(KERN_ERR "%s: couldn't create class\n", __FILE__); 258 return PTR_ERR(rtc_class); 259 } 260 rtc_class->suspend = rtc_suspend; 261 rtc_class->resume = rtc_resume; 262 rtc_dev_init(); 263 rtc_sysfs_init(rtc_class); 264 return 0; 265 } 266 267 static void __exit rtc_exit(void) 268 { 269 rtc_dev_exit(); 270 class_destroy(rtc_class); 271 ida_destroy(&rtc_ida); 272 } 273 274 subsys_initcall(rtc_init); 275 module_exit(rtc_exit); 276 277 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 278 MODULE_DESCRIPTION("RTC class support"); 279 MODULE_LICENSE("GPL"); 280