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