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 19 #include "rtc-core.h" 20 21 22 static DEFINE_IDR(rtc_idr); 23 static DEFINE_MUTEX(idr_lock); 24 struct class *rtc_class; 25 26 static void rtc_device_release(struct device *dev) 27 { 28 struct rtc_device *rtc = to_rtc_device(dev); 29 mutex_lock(&idr_lock); 30 idr_remove(&rtc_idr, rtc->id); 31 mutex_unlock(&idr_lock); 32 kfree(rtc); 33 } 34 35 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE) 36 37 /* 38 * On suspend(), measure the delta between one RTC and the 39 * system's wall clock; restore it on resume(). 40 */ 41 42 static struct timespec delta; 43 static time_t oldtime; 44 45 static int rtc_suspend(struct device *dev, pm_message_t mesg) 46 { 47 struct rtc_device *rtc = to_rtc_device(dev); 48 struct rtc_time tm; 49 50 if (strncmp(rtc->dev.bus_id, 51 CONFIG_RTC_HCTOSYS_DEVICE, 52 BUS_ID_SIZE) != 0) 53 return 0; 54 55 rtc_read_time(rtc, &tm); 56 rtc_tm_to_time(&tm, &oldtime); 57 58 /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */ 59 set_normalized_timespec(&delta, 60 xtime.tv_sec - oldtime, 61 xtime.tv_nsec - (NSEC_PER_SEC >> 1)); 62 63 return 0; 64 } 65 66 static int rtc_resume(struct device *dev) 67 { 68 struct rtc_device *rtc = to_rtc_device(dev); 69 struct rtc_time tm; 70 time_t newtime; 71 struct timespec time; 72 73 if (strncmp(rtc->dev.bus_id, 74 CONFIG_RTC_HCTOSYS_DEVICE, 75 BUS_ID_SIZE) != 0) 76 return 0; 77 78 rtc_read_time(rtc, &tm); 79 if (rtc_valid_tm(&tm) != 0) { 80 pr_debug("%s: bogus resume time\n", rtc->dev.bus_id); 81 return 0; 82 } 83 rtc_tm_to_time(&tm, &newtime); 84 if (newtime <= oldtime) { 85 if (newtime < oldtime) 86 pr_debug("%s: time travel!\n", rtc->dev.bus_id); 87 return 0; 88 } 89 90 /* restore wall clock using delta against this RTC; 91 * adjust again for avg 1/2 second RTC sampling error 92 */ 93 set_normalized_timespec(&time, 94 newtime + delta.tv_sec, 95 (NSEC_PER_SEC >> 1) + delta.tv_nsec); 96 do_settimeofday(&time); 97 98 return 0; 99 } 100 101 #else 102 #define rtc_suspend NULL 103 #define rtc_resume NULL 104 #endif 105 106 107 /** 108 * rtc_device_register - register w/ RTC class 109 * @dev: the device to register 110 * 111 * rtc_device_unregister() must be called when the class device is no 112 * longer needed. 113 * 114 * Returns the pointer to the new struct class device. 115 */ 116 struct rtc_device *rtc_device_register(const char *name, struct device *dev, 117 const struct rtc_class_ops *ops, 118 struct module *owner) 119 { 120 struct rtc_device *rtc; 121 int id, err; 122 123 if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) { 124 err = -ENOMEM; 125 goto exit; 126 } 127 128 129 mutex_lock(&idr_lock); 130 err = idr_get_new(&rtc_idr, NULL, &id); 131 mutex_unlock(&idr_lock); 132 133 if (err < 0) 134 goto exit; 135 136 id = id & MAX_ID_MASK; 137 138 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL); 139 if (rtc == NULL) { 140 err = -ENOMEM; 141 goto exit_idr; 142 } 143 144 rtc->id = id; 145 rtc->ops = ops; 146 rtc->owner = owner; 147 rtc->max_user_freq = 64; 148 rtc->dev.parent = dev; 149 rtc->dev.class = rtc_class; 150 rtc->dev.release = rtc_device_release; 151 152 mutex_init(&rtc->ops_lock); 153 spin_lock_init(&rtc->irq_lock); 154 spin_lock_init(&rtc->irq_task_lock); 155 156 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 157 snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id); 158 159 rtc_dev_prepare(rtc); 160 161 err = device_register(&rtc->dev); 162 if (err) 163 goto exit_kfree; 164 165 rtc_dev_add_device(rtc); 166 rtc_sysfs_add_device(rtc); 167 rtc_proc_add_device(rtc); 168 169 dev_info(dev, "rtc core: registered %s as %s\n", 170 rtc->name, rtc->dev.bus_id); 171 172 return rtc; 173 174 exit_kfree: 175 kfree(rtc); 176 177 exit_idr: 178 mutex_lock(&idr_lock); 179 idr_remove(&rtc_idr, id); 180 mutex_unlock(&idr_lock); 181 182 exit: 183 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 184 name, err); 185 return ERR_PTR(err); 186 } 187 EXPORT_SYMBOL_GPL(rtc_device_register); 188 189 190 /** 191 * rtc_device_unregister - removes the previously registered RTC class device 192 * 193 * @rtc: the RTC class device to destroy 194 */ 195 void rtc_device_unregister(struct rtc_device *rtc) 196 { 197 if (get_device(&rtc->dev) != NULL) { 198 mutex_lock(&rtc->ops_lock); 199 /* remove innards of this RTC, then disable it, before 200 * letting any rtc_class_open() users access it again 201 */ 202 rtc_sysfs_del_device(rtc); 203 rtc_dev_del_device(rtc); 204 rtc_proc_del_device(rtc); 205 device_unregister(&rtc->dev); 206 rtc->ops = NULL; 207 mutex_unlock(&rtc->ops_lock); 208 put_device(&rtc->dev); 209 } 210 } 211 EXPORT_SYMBOL_GPL(rtc_device_unregister); 212 213 static int __init rtc_init(void) 214 { 215 rtc_class = class_create(THIS_MODULE, "rtc"); 216 if (IS_ERR(rtc_class)) { 217 printk(KERN_ERR "%s: couldn't create class\n", __FILE__); 218 return PTR_ERR(rtc_class); 219 } 220 rtc_class->suspend = rtc_suspend; 221 rtc_class->resume = rtc_resume; 222 rtc_dev_init(); 223 rtc_sysfs_init(rtc_class); 224 return 0; 225 } 226 227 static void __exit rtc_exit(void) 228 { 229 rtc_dev_exit(); 230 class_destroy(rtc_class); 231 } 232 233 subsys_initcall(rtc_init); 234 module_exit(rtc_exit); 235 236 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 237 MODULE_DESCRIPTION("RTC class support"); 238 MODULE_LICENSE("GPL"); 239