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 struct timespec ts = current_kernel_time(); 50 51 if (strncmp(rtc->dev.bus_id, 52 CONFIG_RTC_HCTOSYS_DEVICE, 53 BUS_ID_SIZE) != 0) 54 return 0; 55 56 rtc_read_time(rtc, &tm); 57 rtc_tm_to_time(&tm, &oldtime); 58 59 /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */ 60 set_normalized_timespec(&delta, 61 ts.tv_sec - oldtime, 62 ts.tv_nsec - (NSEC_PER_SEC >> 1)); 63 64 return 0; 65 } 66 67 static int rtc_resume(struct device *dev) 68 { 69 struct rtc_device *rtc = to_rtc_device(dev); 70 struct rtc_time tm; 71 time_t newtime; 72 struct timespec time; 73 74 if (strncmp(rtc->dev.bus_id, 75 CONFIG_RTC_HCTOSYS_DEVICE, 76 BUS_ID_SIZE) != 0) 77 return 0; 78 79 rtc_read_time(rtc, &tm); 80 if (rtc_valid_tm(&tm) != 0) { 81 pr_debug("%s: bogus resume time\n", rtc->dev.bus_id); 82 return 0; 83 } 84 rtc_tm_to_time(&tm, &newtime); 85 if (newtime <= oldtime) { 86 if (newtime < oldtime) 87 pr_debug("%s: time travel!\n", rtc->dev.bus_id); 88 return 0; 89 } 90 91 /* restore wall clock using delta against this RTC; 92 * adjust again for avg 1/2 second RTC sampling error 93 */ 94 set_normalized_timespec(&time, 95 newtime + delta.tv_sec, 96 (NSEC_PER_SEC >> 1) + delta.tv_nsec); 97 do_settimeofday(&time); 98 99 return 0; 100 } 101 102 #else 103 #define rtc_suspend NULL 104 #define rtc_resume NULL 105 #endif 106 107 108 /** 109 * rtc_device_register - register w/ RTC class 110 * @dev: the device to register 111 * 112 * rtc_device_unregister() must be called when the class device is no 113 * longer needed. 114 * 115 * Returns the pointer to the new struct class device. 116 */ 117 struct rtc_device *rtc_device_register(const char *name, struct device *dev, 118 const struct rtc_class_ops *ops, 119 struct module *owner) 120 { 121 struct rtc_device *rtc; 122 int id, err; 123 124 if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) { 125 err = -ENOMEM; 126 goto exit; 127 } 128 129 130 mutex_lock(&idr_lock); 131 err = idr_get_new(&rtc_idr, NULL, &id); 132 mutex_unlock(&idr_lock); 133 134 if (err < 0) 135 goto exit; 136 137 id = id & MAX_ID_MASK; 138 139 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL); 140 if (rtc == NULL) { 141 err = -ENOMEM; 142 goto exit_idr; 143 } 144 145 rtc->id = id; 146 rtc->ops = ops; 147 rtc->owner = owner; 148 rtc->max_user_freq = 64; 149 rtc->dev.parent = dev; 150 rtc->dev.class = rtc_class; 151 rtc->dev.release = rtc_device_release; 152 153 mutex_init(&rtc->ops_lock); 154 spin_lock_init(&rtc->irq_lock); 155 spin_lock_init(&rtc->irq_task_lock); 156 157 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE); 158 snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id); 159 160 rtc_dev_prepare(rtc); 161 162 err = device_register(&rtc->dev); 163 if (err) 164 goto exit_kfree; 165 166 rtc_dev_add_device(rtc); 167 rtc_sysfs_add_device(rtc); 168 rtc_proc_add_device(rtc); 169 170 dev_info(dev, "rtc core: registered %s as %s\n", 171 rtc->name, rtc->dev.bus_id); 172 173 return rtc; 174 175 exit_kfree: 176 kfree(rtc); 177 178 exit_idr: 179 mutex_lock(&idr_lock); 180 idr_remove(&rtc_idr, id); 181 mutex_unlock(&idr_lock); 182 183 exit: 184 dev_err(dev, "rtc core: unable to register %s, err = %d\n", 185 name, err); 186 return ERR_PTR(err); 187 } 188 EXPORT_SYMBOL_GPL(rtc_device_register); 189 190 191 /** 192 * rtc_device_unregister - removes the previously registered RTC class device 193 * 194 * @rtc: the RTC class device to destroy 195 */ 196 void rtc_device_unregister(struct rtc_device *rtc) 197 { 198 if (get_device(&rtc->dev) != NULL) { 199 mutex_lock(&rtc->ops_lock); 200 /* remove innards of this RTC, then disable it, before 201 * letting any rtc_class_open() users access it again 202 */ 203 rtc_sysfs_del_device(rtc); 204 rtc_dev_del_device(rtc); 205 rtc_proc_del_device(rtc); 206 device_unregister(&rtc->dev); 207 rtc->ops = NULL; 208 mutex_unlock(&rtc->ops_lock); 209 put_device(&rtc->dev); 210 } 211 } 212 EXPORT_SYMBOL_GPL(rtc_device_unregister); 213 214 static int __init rtc_init(void) 215 { 216 rtc_class = class_create(THIS_MODULE, "rtc"); 217 if (IS_ERR(rtc_class)) { 218 printk(KERN_ERR "%s: couldn't create class\n", __FILE__); 219 return PTR_ERR(rtc_class); 220 } 221 rtc_class->suspend = rtc_suspend; 222 rtc_class->resume = rtc_resume; 223 rtc_dev_init(); 224 rtc_sysfs_init(rtc_class); 225 return 0; 226 } 227 228 static void __exit rtc_exit(void) 229 { 230 rtc_dev_exit(); 231 class_destroy(rtc_class); 232 } 233 234 subsys_initcall(rtc_init); 235 module_exit(rtc_exit); 236 237 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); 238 MODULE_DESCRIPTION("RTC class support"); 239 MODULE_LICENSE("GPL"); 240