rtc-dev.c

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/*
 * RTC subsystem, dev interface
 *
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <[email protected]>
 *
 * based on arch/arm/common/rtctime.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/sched.h>
#include "rtc-core.h"

static dev_t rtc_devt;

#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */

static int rtc_dev_open(struct inode *inode, struct file *file)
{
    int err;
    struct rtc_device *rtc = container_of(inode->i_cdev,
                    struct rtc_device, char_dev);
    const struct rtc_class_ops *ops = rtc->ops;

    if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
        return -EBUSY;

    file->private_data = rtc;

    err = ops->open ? ops->open(rtc->dev.parent) : 0;
    if (err == 0) {
        spin_lock_irq(&rtc->irq_lock);
        rtc->irq_data = 0;
        spin_unlock_irq(&rtc->irq_lock);

        return 0;
    }

    /* something has gone wrong */
    clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
    return err;
}

#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
/*
 * Routine to poll RTC seconds field for change as often as possible,
 * after first RTC_UIE use timer to reduce polling
 */
static void rtc_uie_task(struct work_struct *work)
{
    struct rtc_device *rtc =
        container_of(work, struct rtc_device, uie_task);
    struct rtc_time tm;
    int num = 0;
    int err;

    err = rtc_read_time(rtc, &tm);

    spin_lock_irq(&rtc->irq_lock);
    if (rtc->stop_uie_polling || err) {
        rtc->uie_task_active = 0;
    } else if (rtc->oldsecs != tm.tm_sec) {
        num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
        rtc->oldsecs = tm.tm_sec;
        rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
        rtc->uie_timer_active = 1;
        rtc->uie_task_active = 0;
        add_timer(&rtc->uie_timer);
    } else if (schedule_work(&rtc->uie_task) == 0) {
        rtc->uie_task_active = 0;
    }
    spin_unlock_irq(&rtc->irq_lock);
    if (num)
        rtc_handle_legacy_irq(rtc, num, RTC_UF);
}
static void rtc_uie_timer(unsigned long data)
{
    struct rtc_device *rtc = (struct rtc_device *)data;
    unsigned long flags;

    spin_lock_irqsave(&rtc->irq_lock, flags);
    rtc->uie_timer_active = 0;
    rtc->uie_task_active = 1;
    if ((schedule_work(&rtc->uie_task) == 0))
        rtc->uie_task_active = 0;
    spin_unlock_irqrestore(&rtc->irq_lock, flags);
}

static int clear_uie(struct rtc_device *rtc)
{
    spin_lock_irq(&rtc->irq_lock);
    if (rtc->uie_irq_active) {
        rtc->stop_uie_polling = 1;
        if (rtc->uie_timer_active) {
            spin_unlock_irq(&rtc->irq_lock);
            del_timer_sync(&rtc->uie_timer);
            spin_lock_irq(&rtc->irq_lock);
            rtc->uie_timer_active = 0;
        }
        if (rtc->uie_task_active) {
            spin_unlock_irq(&rtc->irq_lock);
            flush_scheduled_work();
            spin_lock_irq(&rtc->irq_lock);
        }
        rtc->uie_irq_active = 0;
    }
    spin_unlock_irq(&rtc->irq_lock);
    return 0;
}

static int set_uie(struct rtc_device *rtc)
{
    struct rtc_time tm;
    int err;

    err = rtc_read_time(rtc, &tm);
    if (err)
        return err;
    spin_lock_irq(&rtc->irq_lock);
    if (!rtc->uie_irq_active) {
        rtc->uie_irq_active = 1;
        rtc->stop_uie_polling = 0;
        rtc->oldsecs = tm.tm_sec;
        rtc->uie_task_active = 1;
        if (schedule_work(&rtc->uie_task) == 0)
            rtc->uie_task_active = 0;
    }
    rtc->irq_data = 0;
    spin_unlock_irq(&rtc->irq_lock);
    return 0;
}

int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled)
{
    if (enabled)
        return set_uie(rtc);
    else
        return clear_uie(rtc);
}
EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul);

#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */

static ssize_t
rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
    struct rtc_device *rtc = file->private_data;

    DECLARE_WAITQUEUE(wait, current);
    unsigned long data;
    ssize_t ret;

    if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
        return -EINVAL;

    add_wait_queue(&rtc->irq_queue, &wait);
    do {
        __set_current_state(TASK_INTERRUPTIBLE);

        spin_lock_irq(&rtc->irq_lock);
        data = rtc->irq_data;
        rtc->irq_data = 0;
        spin_unlock_irq(&rtc->irq_lock);

        if (data != 0) {
            ret = 0;
            break;
        }
        if (file->f_flags & O_NONBLOCK) {
            ret = -EAGAIN;
            break;
        }
        if (signal_pending(current)) {
            ret = -ERESTARTSYS;
            break;
        }
        schedule();
    } while (1);
    set_current_state(TASK_RUNNING);
    remove_wait_queue(&rtc->irq_queue, &wait);

    if (ret == 0) {
        /* Check for any data updates */
        if (rtc->ops->read_callback)
            data = rtc->ops->read_callback(rtc->dev.parent,
                               data);

        if (sizeof(int) != sizeof(long) &&
            count == sizeof(unsigned int))
            ret = put_user(data, (unsigned int __user *)buf) ?:
                sizeof(unsigned int);
        else
            ret = put_user(data, (unsigned long __user *)buf) ?:
                sizeof(unsigned long);
    }
    return ret;
}

static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
{
    struct rtc_device *rtc = file->private_data;
    unsigned long data;

    poll_wait(file, &rtc->irq_queue, wait);

    data = rtc->irq_data;

    return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
}

static long rtc_dev_ioctl(struct file *file,
        unsigned int cmd, unsigned long arg)
{
    int err = 0;
    struct rtc_device *rtc = file->private_data;
    const struct rtc_class_ops *ops = rtc->ops;
    struct rtc_time tm;
    struct rtc_wkalrm alarm;
    void __user *uarg = (void __user *) arg;

    err = mutex_lock_interruptible(&rtc->ops_lock);
    if (err)
        return err;

    /* check that the calling task has appropriate permissions
     * for certain ioctls. doing this check here is useful
     * to avoid duplicate code in each driver.
     */
    switch (cmd) {
    case RTC_EPOCH_SET:
    case RTC_SET_TIME:
        if (!capable(CAP_SYS_TIME))
            err = -EACCES;
        break;

    case RTC_IRQP_SET:
        if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
            err = -EACCES;
        break;

    case RTC_PIE_ON:
        if (rtc->irq_freq > rtc->max_user_freq &&
                !capable(CAP_SYS_RESOURCE))
            err = -EACCES;
        break;
    }

    if (err)
        goto done;

    /*
     * Drivers *SHOULD NOT* provide ioctl implementations
     * for these requests.  Instead, provide methods to
     * support the following code, so that the RTC's main
     * features are accessible without using ioctls.
     *
     * RTC and alarm times will be in UTC, by preference,
     * but dual-booting with MS-Windows implies RTCs must
     * use the local wall clock time.
     */

    switch (cmd) {
    case RTC_ALM_READ:
        mutex_unlock(&rtc->ops_lock);

        err = rtc_read_alarm(rtc, &alarm);
        if (err < 0)
            return err;

        if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
            err = -EFAULT;
        return err;

    case RTC_ALM_SET:
        mutex_unlock(&rtc->ops_lock);

        if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
            return -EFAULT;

        alarm.enabled = 0;
        alarm.pending = 0;
        alarm.time.tm_wday = -1;
        alarm.time.tm_yday = -1;
        alarm.time.tm_isdst = -1;

        /* RTC_ALM_SET alarms may be up to 24 hours in the future.
         * Rather than expecting every RTC to implement "don't care"
         * for day/month/year fields, just force the alarm to have
         * the right values for those fields.
         *
         * RTC_WKALM_SET should be used instead.  Not only does it
         * eliminate the need for a separate RTC_AIE_ON call, it
         * doesn't have the "alarm 23:59:59 in the future" race.
         *
         * NOTE:  some legacy code may have used invalid fields as
         * wildcards, exposing hardware "periodic alarm" capabilities.
         * Not supported here.
         */
        {
            unsigned long now, then;

            err = rtc_read_time(rtc, &tm);
            if (err < 0)
                return err;
            rtc_tm_to_time(&tm, &now);

            alarm.time.tm_mday = tm.tm_mday;
            alarm.time.tm_mon = tm.tm_mon;
            alarm.time.tm_year = tm.tm_year;
            err  = rtc_valid_tm(&alarm.time);
            if (err < 0)
                return err;
            rtc_tm_to_time(&alarm.time, &then);

            /* alarm may need to wrap into tomorrow */
            if (then < now) {
                rtc_time_to_tm(now + 24 * 60 * 60, &tm);
                alarm.time.tm_mday = tm.tm_mday;
                alarm.time.tm_mon = tm.tm_mon;
                alarm.time.tm_year = tm.tm_year;
            }
        }

        return rtc_set_alarm(rtc, &alarm);

    case RTC_RD_TIME:
        mutex_unlock(&rtc->ops_lock);

        err = rtc_read_time(rtc, &tm);
        if (err < 0)
            return err;

        if (copy_to_user(uarg, &tm, sizeof(tm)))
            err = -EFAULT;
        return err;

    case RTC_SET_TIME:
        mutex_unlock(&rtc->ops_lock);

        if (copy_from_user(&tm, uarg, sizeof(tm)))
            return -EFAULT;

        return rtc_set_time(rtc, &tm);

    case RTC_PIE_ON:
        err = rtc_irq_set_state(rtc, NULL, 1);
        break;

    case RTC_PIE_OFF:
        err = rtc_irq_set_state(rtc, NULL, 0);
        break;

    case RTC_AIE_ON:
        mutex_unlock(&rtc->ops_lock);
        return rtc_alarm_irq_enable(rtc, 1);

    case RTC_AIE_OFF:
        mutex_unlock(&rtc->ops_lock);
        return rtc_alarm_irq_enable(rtc, 0);

    case RTC_UIE_ON:
        mutex_unlock(&rtc->ops_lock);
        return rtc_update_irq_enable(rtc, 1);

    case RTC_UIE_OFF:
        mutex_unlock(&rtc->ops_lock);
        return rtc_update_irq_enable(rtc, 0);

    case RTC_IRQP_SET:
        err = rtc_irq_set_freq(rtc, NULL, arg);
        break;

    case RTC_IRQP_READ:
        err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
        break;

#if 0
    case RTC_EPOCH_SET:
#ifndef rtc_epoch
        /*
         * There were no RTC clocks before 1900.
         */
        if (arg < 1900) {
            err = -EINVAL;
            break;
        }
        rtc_epoch = arg;
        err = 0;
#endif
        break;

    case RTC_EPOCH_READ:
        err = put_user(rtc_epoch, (unsigned long __user *)uarg);
        break;
#endif
    case RTC_WKALM_SET:
        mutex_unlock(&rtc->ops_lock);
        if (copy_from_user(&alarm, uarg, sizeof(alarm)))
            return -EFAULT;

        return rtc_set_alarm(rtc, &alarm);

    case RTC_WKALM_RD:
        mutex_unlock(&rtc->ops_lock);
        err = rtc_read_alarm(rtc, &alarm);
        if (err < 0)
            return err;

        if (copy_to_user(uarg, &alarm, sizeof(alarm)))
            err = -EFAULT;
        return err;

    default:
        /* Finally try the driver's ioctl interface */
        if (ops->ioctl) {
            err = ops->ioctl(rtc->dev.parent, cmd, arg);
            if (err == -ENOIOCTLCMD)
                err = -ENOTTY;
        } else
            err = -ENOTTY;
        break;
    }

done:
    mutex_unlock(&rtc->ops_lock);
    return err;
}

static int rtc_dev_fasync(int fd, struct file *file, int on)
{
    struct rtc_device *rtc = file->private_data;
    return fasync_helper(fd, file, on, &rtc->async_queue);
}

static int rtc_dev_release(struct inode *inode, struct file *file)
{
    struct rtc_device *rtc = file->private_data;

    /* We shut down the repeating IRQs that userspace enabled,
     * since nothing is listening to them.
     *  - Update (UIE) ... currently only managed through ioctls
     *  - Periodic (PIE) ... also used through rtc_*() interface calls
     *
     * Leave the alarm alone; it may be set to trigger a system wakeup
     * later, or be used by kernel code, and is a one-shot event anyway.
     */

    /* Keep ioctl until all drivers are converted */
    rtc_dev_ioctl(file, RTC_UIE_OFF, 0);
    rtc_update_irq_enable(rtc, 0);
    rtc_irq_set_state(rtc, NULL, 0);

    if (rtc->ops->release)
        rtc->ops->release(rtc->dev.parent);

    clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
    return 0;
}

static const struct file_operations rtc_dev_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .read       = rtc_dev_read,
    .poll       = rtc_dev_poll,
    .unlocked_ioctl = rtc_dev_ioctl,
    .open       = rtc_dev_open,
    .release    = rtc_dev_release,
    .fasync     = rtc_dev_fasync,
};

/* insertion/removal hooks */

void rtc_dev_prepare(struct rtc_device *rtc)
{
    if (!rtc_devt)
        return;

    if (rtc->id >= RTC_DEV_MAX) {
        pr_debug("%s: too many RTC devices\n", rtc->name);
        return;
    }

    rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);

#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
    INIT_WORK(&rtc->uie_task, rtc_uie_task);
    setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
#endif

    cdev_init(&rtc->char_dev, &rtc_dev_fops);
    rtc->char_dev.owner = rtc->owner;
}

void rtc_dev_add_device(struct rtc_device *rtc)
{
    if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
        printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
            rtc->name, MAJOR(rtc_devt), rtc->id);
    else
        pr_debug("%s: dev (%d:%d)\n", rtc->name,
            MAJOR(rtc_devt), rtc->id);
}

void rtc_dev_del_device(struct rtc_device *rtc)
{
    if (rtc->dev.devt)
        cdev_del(&rtc->char_dev);
}

void __init rtc_dev_init(void)
{
    int err;

    err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
    if (err < 0)
        printk(KERN_ERR "%s: failed to allocate char dev region\n",
            __FILE__);
}

void __exit rtc_dev_exit(void)
{
    if (rtc_devt)
        unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
}