linux/drivers/rtc/rtc-dev.c
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   1/*
   2 * RTC subsystem, dev interface
   3 *
   4 * Copyright (C) 2005 Tower Technologies
   5 * Author: Alessandro Zummo <a.zummo@towertech.it>
   6 *
   7 * based on arch/arm/common/rtctime.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/sched.h>
  17#include "rtc-core.h"
  18
  19static dev_t rtc_devt;
  20
  21#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
  22
  23static int rtc_dev_open(struct inode *inode, struct file *file)
  24{
  25        int err;
  26        struct rtc_device *rtc = container_of(inode->i_cdev,
  27                                        struct rtc_device, char_dev);
  28        const struct rtc_class_ops *ops = rtc->ops;
  29
  30        if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
  31                return -EBUSY;
  32
  33        file->private_data = rtc;
  34
  35        err = ops->open ? ops->open(rtc->dev.parent) : 0;
  36        if (err == 0) {
  37                spin_lock_irq(&rtc->irq_lock);
  38                rtc->irq_data = 0;
  39                spin_unlock_irq(&rtc->irq_lock);
  40
  41                return 0;
  42        }
  43
  44        /* something has gone wrong */
  45        clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
  46        return err;
  47}
  48
  49#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
  50/*
  51 * Routine to poll RTC seconds field for change as often as possible,
  52 * after first RTC_UIE use timer to reduce polling
  53 */
  54static void rtc_uie_task(struct work_struct *work)
  55{
  56        struct rtc_device *rtc =
  57                container_of(work, struct rtc_device, uie_task);
  58        struct rtc_time tm;
  59        int num = 0;
  60        int err;
  61
  62        err = rtc_read_time(rtc, &tm);
  63
  64        spin_lock_irq(&rtc->irq_lock);
  65        if (rtc->stop_uie_polling || err) {
  66                rtc->uie_task_active = 0;
  67        } else if (rtc->oldsecs != tm.tm_sec) {
  68                num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
  69                rtc->oldsecs = tm.tm_sec;
  70                rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
  71                rtc->uie_timer_active = 1;
  72                rtc->uie_task_active = 0;
  73                add_timer(&rtc->uie_timer);
  74        } else if (schedule_work(&rtc->uie_task) == 0) {
  75                rtc->uie_task_active = 0;
  76        }
  77        spin_unlock_irq(&rtc->irq_lock);
  78        if (num)
  79                rtc_handle_legacy_irq(rtc, num, RTC_UF);
  80}
  81static void rtc_uie_timer(unsigned long data)
  82{
  83        struct rtc_device *rtc = (struct rtc_device *)data;
  84        unsigned long flags;
  85
  86        spin_lock_irqsave(&rtc->irq_lock, flags);
  87        rtc->uie_timer_active = 0;
  88        rtc->uie_task_active = 1;
  89        if ((schedule_work(&rtc->uie_task) == 0))
  90                rtc->uie_task_active = 0;
  91        spin_unlock_irqrestore(&rtc->irq_lock, flags);
  92}
  93
  94static int clear_uie(struct rtc_device *rtc)
  95{
  96        spin_lock_irq(&rtc->irq_lock);
  97        if (rtc->uie_irq_active) {
  98                rtc->stop_uie_polling = 1;
  99                if (rtc->uie_timer_active) {
 100                        spin_unlock_irq(&rtc->irq_lock);
 101                        del_timer_sync(&rtc->uie_timer);
 102                        spin_lock_irq(&rtc->irq_lock);
 103                        rtc->uie_timer_active = 0;
 104                }
 105                if (rtc->uie_task_active) {
 106                        spin_unlock_irq(&rtc->irq_lock);
 107                        flush_scheduled_work();
 108                        spin_lock_irq(&rtc->irq_lock);
 109                }
 110                rtc->uie_irq_active = 0;
 111        }
 112        spin_unlock_irq(&rtc->irq_lock);
 113        return 0;
 114}
 115
 116static int set_uie(struct rtc_device *rtc)
 117{
 118        struct rtc_time tm;
 119        int err;
 120
 121        err = rtc_read_time(rtc, &tm);
 122        if (err)
 123                return err;
 124        spin_lock_irq(&rtc->irq_lock);
 125        if (!rtc->uie_irq_active) {
 126                rtc->uie_irq_active = 1;
 127                rtc->stop_uie_polling = 0;
 128                rtc->oldsecs = tm.tm_sec;
 129                rtc->uie_task_active = 1;
 130                if (schedule_work(&rtc->uie_task) == 0)
 131                        rtc->uie_task_active = 0;
 132        }
 133        rtc->irq_data = 0;
 134        spin_unlock_irq(&rtc->irq_lock);
 135        return 0;
 136}
 137
 138int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
 139{
 140        if (enabled)
 141                return set_uie(rtc);
 142        else
 143                return clear_uie(rtc);
 144}
 145EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);
 146
 147#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
 148
 149static ssize_t
 150rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 151{
 152        struct rtc_device *rtc = file->private_data;
 153
 154        DECLARE_WAITQUEUE(wait, current);
 155        unsigned long data;
 156        ssize_t ret;
 157
 158        if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
 159                return -EINVAL;
 160
 161        add_wait_queue(&rtc->irq_queue, &wait);
 162        do {
 163                __set_current_state(TASK_INTERRUPTIBLE);
 164
 165                spin_lock_irq(&rtc->irq_lock);
 166                data = rtc->irq_data;
 167                rtc->irq_data = 0;
 168                spin_unlock_irq(&rtc->irq_lock);
 169
 170                if (data != 0) {
 171                        ret = 0;
 172                        break;
 173                }
 174                if (file->f_flags & O_NONBLOCK) {
 175                        ret = -EAGAIN;
 176                        break;
 177                }
 178                if (signal_pending(current)) {
 179                        ret = -ERESTARTSYS;
 180                        break;
 181                }
 182                schedule();
 183        } while (1);
 184        set_current_state(TASK_RUNNING);
 185        remove_wait_queue(&rtc->irq_queue, &wait);
 186
 187        if (ret == 0) {
 188                /* Check for any data updates */
 189                if (rtc->ops->read_callback)
 190                        data = rtc->ops->read_callback(rtc->dev.parent,
 191                                                       data);
 192
 193                if (sizeof(int) != sizeof(long) &&
 194                    count == sizeof(unsigned int))
 195                        ret = put_user(data, (unsigned int __user *)buf) ?:
 196                                sizeof(unsigned int);
 197                else
 198                        ret = put_user(data, (unsigned long __user *)buf) ?:
 199                                sizeof(unsigned long);
 200        }
 201        return ret;
 202}
 203
 204static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
 205{
 206        struct rtc_device *rtc = file->private_data;
 207        unsigned long data;
 208
 209        poll_wait(file, &rtc->irq_queue, wait);
 210
 211        data = rtc->irq_data;
 212
 213        return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
 214}
 215
 216static long rtc_dev_ioctl(struct file *file,
 217                unsigned int cmd, unsigned long arg)
 218{
 219        int err = 0;
 220        struct rtc_device *rtc = file->private_data;
 221        const struct rtc_class_ops *ops = rtc->ops;
 222        struct rtc_time tm;
 223        struct rtc_wkalrm alarm;
 224        void __user *uarg = (void __user *) arg;
 225
 226        err = mutex_lock_interruptible(&rtc->ops_lock);
 227        if (err)
 228                return err;
 229
 230        /* check that the calling task has appropriate permissions
 231         * for certain ioctls. doing this check here is useful
 232         * to avoid duplicate code in each driver.
 233         */
 234        switch (cmd) {
 235        case RTC_EPOCH_SET:
 236        case RTC_SET_TIME:
 237                if (!capable(CAP_SYS_TIME))
 238                        err = -EACCES;
 239                break;
 240
 241        case RTC_IRQP_SET:
 242                if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
 243                        err = -EACCES;
 244                break;
 245
 246        case RTC_PIE_ON:
 247                if (rtc->irq_freq > rtc->max_user_freq &&
 248                                !capable(CAP_SYS_RESOURCE))
 249                        err = -EACCES;
 250                break;
 251        }
 252
 253        if (err)
 254                goto done;
 255
 256        /*
 257         * Drivers *SHOULD NOT* provide ioctl implementations
 258         * for these requests.  Instead, provide methods to
 259         * support the following code, so that the RTC's main
 260         * features are accessible without using ioctls.
 261         *
 262         * RTC and alarm times will be in UTC, by preference,
 263         * but dual-booting with MS-Windows implies RTCs must
 264         * use the local wall clock time.
 265         */
 266
 267        switch (cmd) {
 268        case RTC_ALM_READ:
 269                mutex_unlock(&rtc->ops_lock);
 270
 271                err = rtc_read_alarm(rtc, &alarm);
 272                if (err < 0)
 273                        return err;
 274
 275                if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
 276                        err = -EFAULT;
 277                return err;
 278
 279        case RTC_ALM_SET:
 280                mutex_unlock(&rtc->ops_lock);
 281
 282                if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
 283                        return -EFAULT;
 284
 285                alarm.enabled = 0;
 286                alarm.pending = 0;
 287                alarm.time.tm_wday = -1;
 288                alarm.time.tm_yday = -1;
 289                alarm.time.tm_isdst = -1;
 290
 291                /* RTC_ALM_SET alarms may be up to 24 hours in the future.
 292                 * Rather than expecting every RTC to implement "don't care"
 293                 * for day/month/year fields, just force the alarm to have
 294                 * the right values for those fields.
 295                 *
 296                 * RTC_WKALM_SET should be used instead.  Not only does it
 297                 * eliminate the need for a separate RTC_AIE_ON call, it
 298                 * doesn't have the "alarm 23:59:59 in the future" race.
 299                 *
 300                 * NOTE:  some legacy code may have used invalid fields as
 301                 * wildcards, exposing hardware "periodic alarm" capabilities.
 302                 * Not supported here.
 303                 */
 304                {
 305                        unsigned long now, then;
 306
 307                        err = rtc_read_time(rtc, &tm);
 308                        if (err < 0)
 309                                return err;
 310                        rtc_tm_to_time(&tm, &now);
 311
 312                        alarm.time.tm_mday = tm.tm_mday;
 313                        alarm.time.tm_mon = tm.tm_mon;
 314                        alarm.time.tm_year = tm.tm_year;
 315                        err  = rtc_valid_tm(&alarm.time);
 316                        if (err < 0)
 317                                return err;
 318                        rtc_tm_to_time(&alarm.time, &then);
 319
 320                        /* alarm may need to wrap into tomorrow */
 321                        if (then < now) {
 322                                rtc_time_to_tm(now + 24 * 60 * 60, &tm);
 323                                alarm.time.tm_mday = tm.tm_mday;
 324                                alarm.time.tm_mon = tm.tm_mon;
 325                                alarm.time.tm_year = tm.tm_year;
 326                        }
 327                }
 328
 329                return rtc_set_alarm(rtc, &alarm);
 330
 331        case RTC_RD_TIME:
 332                mutex_unlock(&rtc->ops_lock);
 333
 334                err = rtc_read_time(rtc, &tm);
 335                if (err < 0)
 336                        return err;
 337
 338                if (copy_to_user(uarg, &tm, sizeof(tm)))
 339                        err = -EFAULT;
 340                return err;
 341
 342        case RTC_SET_TIME:
 343                mutex_unlock(&rtc->ops_lock);
 344
 345                if (copy_from_user(&tm, uarg, sizeof(tm)))
 346                        return -EFAULT;
 347
 348                return rtc_set_time(rtc, &tm);
 349
 350        case RTC_PIE_ON:
 351                err = rtc_irq_set_state(rtc, NULL, 1);
 352                break;
 353
 354        case RTC_PIE_OFF:
 355                err = rtc_irq_set_state(rtc, NULL, 0);
 356                break;
 357
 358        case RTC_AIE_ON:
 359                mutex_unlock(&rtc->ops_lock);
 360                return rtc_alarm_irq_enable(rtc, 1);
 361
 362        case RTC_AIE_OFF:
 363                mutex_unlock(&rtc->ops_lock);
 364                return rtc_alarm_irq_enable(rtc, 0);
 365
 366        case RTC_UIE_ON:
 367                mutex_unlock(&rtc->ops_lock);
 368                return rtc_update_irq_enable(rtc, 1);
 369
 370        case RTC_UIE_OFF:
 371                mutex_unlock(&rtc->ops_lock);
 372                return rtc_update_irq_enable(rtc, 0);
 373
 374        case RTC_IRQP_SET:
 375                err = rtc_irq_set_freq(rtc, NULL, arg);
 376                break;
 377
 378        case RTC_IRQP_READ:
 379                err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 380                break;
 381
 382        case RTC_WKALM_SET:
 383                mutex_unlock(&rtc->ops_lock);
 384                if (copy_from_user(&alarm, uarg, sizeof(alarm)))
 385                        return -EFAULT;
 386
 387                return rtc_set_alarm(rtc, &alarm);
 388
 389        case RTC_WKALM_RD:
 390                mutex_unlock(&rtc->ops_lock);
 391                err = rtc_read_alarm(rtc, &alarm);
 392                if (err < 0)
 393                        return err;
 394
 395                if (copy_to_user(uarg, &alarm, sizeof(alarm)))
 396                        err = -EFAULT;
 397                return err;
 398
 399        default:
 400                /* Finally try the driver's ioctl interface */
 401                if (ops->ioctl) {
 402                        err = ops->ioctl(rtc->dev.parent, cmd, arg);
 403                        if (err == -ENOIOCTLCMD)
 404                                err = -ENOTTY;
 405                } else
 406                        err = -ENOTTY;
 407                break;
 408        }
 409
 410done:
 411        mutex_unlock(&rtc->ops_lock);
 412        return err;
 413}
 414
 415static int rtc_dev_fasync(int fd, struct file *file, int on)
 416{
 417        struct rtc_device *rtc = file->private_data;
 418        return fasync_helper(fd, file, on, &rtc->async_queue);
 419}
 420
 421static int rtc_dev_release(struct inode *inode, struct file *file)
 422{
 423        struct rtc_device *rtc = file->private_data;
 424
 425        /* We shut down the repeating IRQs that userspace enabled,
 426         * since nothing is listening to them.
 427         *  - Update (UIE) ... currently only managed through ioctls
 428         *  - Periodic (PIE) ... also used through rtc_*() interface calls
 429         *
 430         * Leave the alarm alone; it may be set to trigger a system wakeup
 431         * later, or be used by kernel code, and is a one-shot event anyway.
 432         */
 433
 434        /* Keep ioctl until all drivers are converted */
 435        rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
 436        rtc_update_irq_enable(rtc, 0);
 437        rtc_irq_set_state(rtc, NULL, 0);
 438
 439        if (rtc->ops->release)
 440                rtc->ops->release(rtc->dev.parent);
 441
 442        clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 443        return 0;
 444}
 445
 446static const struct file_operations rtc_dev_fops = {
 447        .owner          = THIS_MODULE,
 448        .llseek         = no_llseek,
 449        .read           = rtc_dev_read,
 450        .poll           = rtc_dev_poll,
 451        .unlocked_ioctl = rtc_dev_ioctl,
 452        .open           = rtc_dev_open,
 453        .release        = rtc_dev_release,
 454        .fasync         = rtc_dev_fasync,
 455};
 456
 457/* insertion/removal hooks */
 458
 459void rtc_dev_prepare(struct rtc_device *rtc)
 460{
 461        if (!rtc_devt)
 462                return;
 463
 464        if (rtc->id >= RTC_DEV_MAX) {
 465                pr_debug("%s: too many RTC devices\n", rtc->name);
 466                return;
 467        }
 468
 469        rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 470
 471#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 472        INIT_WORK(&rtc->uie_task, rtc_uie_task);
 473        setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
 474#endif
 475
 476        cdev_init(&rtc->char_dev, &rtc_dev_fops);
 477        rtc->char_dev.owner = rtc->owner;
 478}
 479
 480void rtc_dev_add_device(struct rtc_device *rtc)
 481{
 482        if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
 483                printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
 484                        rtc->name, MAJOR(rtc_devt), rtc->id);
 485        else
 486                pr_debug("%s: dev (%d:%d)\n", rtc->name,
 487                        MAJOR(rtc_devt), rtc->id);
 488}
 489
 490void rtc_dev_del_device(struct rtc_device *rtc)
 491{
 492        if (rtc->dev.devt)
 493                cdev_del(&rtc->char_dev);
 494}
 495
 496void __init rtc_dev_init(void)
 497{
 498        int err;
 499
 500        err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
 501        if (err < 0)
 502                printk(KERN_ERR "%s: failed to allocate char dev region\n",
 503                        __FILE__);
 504}
 505
 506void __exit rtc_dev_exit(void)
 507{
 508        if (rtc_devt)
 509                unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
 510}
 511
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