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