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/*

 * RTC subsystem, base class

 *

 * Copyright (C) 2005 Tower Technologies

 * Author: Alessandro Zummo <a.zummo@towertech.it>

 *

 * class skeleton from drivers/hwmon/hwmon.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/kdev_t.h>

#include <linux/idr.h>

#include "rtc-core.h"

static DEFINE_IDR(rtc_idr);

static DEFINE_MUTEX(idr_lock);

struct class *rtc_class;

static void rtc_device_release(struct device *dev)

{

        struct rtc_device *rtc = to_rtc_device(dev);

        mutex_lock(&idr_lock);

        idr_remove(&rtc_idr, rtc->id);

        mutex_unlock(&idr_lock);

        kfree(rtc);

}

#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)

/*

 * On suspend(), measure the delta between one RTC and the

 * system's wall clock; restore it on resume().

 */

static struct timespec  delta;

static time_t           oldtime;

static int rtc_suspend(struct device *dev, pm_message_t mesg)

{

        struct rtc_device       *rtc = to_rtc_device(dev);

        struct rtc_time         tm;

        struct timespec         ts = current_kernel_time();

        if (strncmp(rtc->dev.bus_id,

                                CONFIG_RTC_HCTOSYS_DEVICE,

                                BUS_ID_SIZE) != 0)

                return 0;

        rtc_read_time(rtc, &tm);

        rtc_tm_to_time(&tm, &oldtime);

        /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */

        set_normalized_timespec(&delta,

                                ts.tv_sec - oldtime,

                                ts.tv_nsec - (NSEC_PER_SEC >> 1));

        return 0;

}

static int rtc_resume(struct device *dev)

{

        struct rtc_device       *rtc = to_rtc_device(dev);

        struct rtc_time         tm;

        time_t                  newtime;

        struct timespec         time;

        if (strncmp(rtc->dev.bus_id,

                                CONFIG_RTC_HCTOSYS_DEVICE,

                                BUS_ID_SIZE) != 0)

                return 0;

        rtc_read_time(rtc, &tm);

        if (rtc_valid_tm(&tm) != 0) {

                pr_debug("%s:  bogus resume time\n", rtc->dev.bus_id);

                return 0;

        }

        rtc_tm_to_time(&tm, &newtime);

        if (newtime <= oldtime) {

                if (newtime < oldtime)

                        pr_debug("%s:  time travel!\n", rtc->dev.bus_id);

                return 0;

        }

        /* restore wall clock using delta against this RTC;

         * adjust again for avg 1/2 second RTC sampling error

         */

        set_normalized_timespec(&time,

                                newtime + delta.tv_sec,

                                (NSEC_PER_SEC >> 1) + delta.tv_nsec);

        do_settimeofday(&time);

        return 0;

}

#else

#define rtc_suspend     NULL

#define rtc_resume      NULL

#endif

/**

 * rtc_device_register - register w/ RTC class

 * @dev: the device to register

 *

 * rtc_device_unregister() must be called when the class device is no

 * longer needed.

 *

 * Returns the pointer to the new struct class device.

 */

struct rtc_device *rtc_device_register(const char *name, struct device *dev,

                                        const struct rtc_class_ops *ops,

                                        struct module *owner)

{

        struct rtc_device *rtc;

        int id, err;

        if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {

                err = -ENOMEM;

                goto exit;

        }

        mutex_lock(&idr_lock);

        err = idr_get_new(&rtc_idr, NULL, &id);

        mutex_unlock(&idr_lock);

        if (err < 0)

                goto exit;

        id = id & MAX_ID_MASK;

        rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);

        if (rtc == NULL) {

                err = -ENOMEM;

                goto exit_idr;

        }

        rtc->id = id;

        rtc->ops = ops;

        rtc->owner = owner;

        rtc->max_user_freq = 64;

        rtc->dev.parent = dev;

        rtc->dev.class = rtc_class;

        rtc->dev.release = rtc_device_release;

        mutex_init(&rtc->ops_lock);

        spin_lock_init(&rtc->irq_lock);

        spin_lock_init(&rtc->irq_task_lock);

        init_waitqueue_head(&rtc->irq_queue);

        strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);

        snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);

        rtc_dev_prepare(rtc);

        err = device_register(&rtc->dev);

        if (err)

                goto exit_kfree;

        rtc_dev_add_device(rtc);

        rtc_sysfs_add_device(rtc);

        rtc_proc_add_device(rtc);

        dev_info(dev, "rtc core: registered %s as %s\n",

                        rtc->name, rtc->dev.bus_id);

        return rtc;

exit_kfree:

        kfree(rtc);

exit_idr:

        mutex_lock(&idr_lock);

        idr_remove(&rtc_idr, id);

        mutex_unlock(&idr_lock);

exit:

        dev_err(dev, "rtc core: unable to register %s, err = %d\n",

                        name, err);

        return ERR_PTR(err);

}

EXPORT_SYMBOL_GPL(rtc_device_register);

/**

 * rtc_device_unregister - removes the previously registered RTC class device

 *

 * @rtc: the RTC class device to destroy

 */

void rtc_device_unregister(struct rtc_device *rtc)

{

        if (get_device(&rtc->dev) != NULL) {

                mutex_lock(&rtc->ops_lock);

                /* remove innards of this RTC, then disable it, before

                 * letting any rtc_class_open() users access it again

                 */

                rtc_sysfs_del_device(rtc);

                rtc_dev_del_device(rtc);

                rtc_proc_del_device(rtc);

                device_unregister(&rtc->dev);

                rtc->ops = NULL;

                mutex_unlock(&rtc->ops_lock);

                put_device(&rtc->dev);

        }

}

EXPORT_SYMBOL_GPL(rtc_device_unregister);

static int __init rtc_init(void)

{

        rtc_class = class_create(THIS_MODULE, "rtc");

        if (IS_ERR(rtc_class)) {

                printk(KERN_ERR "%s: couldn't create class\n", __FILE__);

                return PTR_ERR(rtc_class);

        }

        rtc_class->suspend = rtc_suspend;

        rtc_class->resume = rtc_resume;

        rtc_dev_init();

        rtc_sysfs_init(rtc_class);

        return 0;

}

static void __exit rtc_exit(void)

{

        rtc_dev_exit();

        class_destroy(rtc_class);

}

subsys_initcall(rtc_init);

module_exit(rtc_exit);

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");

MODULE_DESCRIPTION("RTC class support");

MODULE_LICENSE("GPL");