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/*

 *  Driver for NEC VR4100 series Real Time Clock unit.

 *

 *  Copyright (C) 2003-2006  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <linux/err.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/ioport.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/rtc.h>

#include <linux/spinlock.h>

#include <linux/types.h>

#include <asm/div64.h>

#include <asm/io.h>

#include <asm/uaccess.h>

MODULE_AUTHOR("Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>");

MODULE_DESCRIPTION("NEC VR4100 series RTC driver");

MODULE_LICENSE("GPL");

/* RTC 1 registers */

#define ETIMELREG               0x00

#define ETIMEMREG               0x02

#define ETIMEHREG               0x04

/* RFU */

#define ECMPLREG                0x08

#define ECMPMREG                0x0a

#define ECMPHREG                0x0c

/* RFU */

#define RTCL1LREG               0x10

#define RTCL1HREG               0x12

#define RTCL1CNTLREG            0x14

#define RTCL1CNTHREG            0x16

#define RTCL2LREG               0x18

#define RTCL2HREG               0x1a

#define RTCL2CNTLREG            0x1c

#define RTCL2CNTHREG            0x1e

/* RTC 2 registers */

#define TCLKLREG                0x00

#define TCLKHREG                0x02

#define TCLKCNTLREG             0x04

#define TCLKCNTHREG             0x06

/* RFU */

#define RTCINTREG               0x1e

 #define TCLOCK_INT             0x08

 #define RTCLONG2_INT           0x04

 #define RTCLONG1_INT           0x02

 #define ELAPSEDTIME_INT        0x01

#define RTC_FREQUENCY           32768

#define MAX_PERIODIC_RATE       6553

static void __iomem *rtc1_base;

static void __iomem *rtc2_base;

#define rtc1_read(offset)               readw(rtc1_base + (offset))

#define rtc1_write(offset, value)       writew((value), rtc1_base + (offset))

#define rtc2_read(offset)               readw(rtc2_base + (offset))

#define rtc2_write(offset, value)       writew((value), rtc2_base + (offset))

static unsigned long epoch = 1970;      /* Jan 1 1970 00:00:00 */

static DEFINE_SPINLOCK(rtc_lock);

static char rtc_name[] = "RTC";

static unsigned long periodic_frequency;

static unsigned long periodic_count;

static unsigned int alarm_enabled;

static int aie_irq = -1;

static int pie_irq = -1;

static inline unsigned long read_elapsed_second(void)

{

        unsigned long first_low, first_mid, first_high;

        unsigned long second_low, second_mid, second_high;

        do {

                first_low = rtc1_read(ETIMELREG);

                first_mid = rtc1_read(ETIMEMREG);

                first_high = rtc1_read(ETIMEHREG);

                second_low = rtc1_read(ETIMELREG);

                second_mid = rtc1_read(ETIMEMREG);

                second_high = rtc1_read(ETIMEHREG);

        } while (first_low != second_low || first_mid != second_mid ||

                 first_high != second_high);

        return (first_high << 17) | (first_mid << 1) | (first_low >> 15);

}

static inline void write_elapsed_second(unsigned long sec)

{

        spin_lock_irq(&rtc_lock);

        rtc1_write(ETIMELREG, (uint16_t)(sec << 15));

        rtc1_write(ETIMEMREG, (uint16_t)(sec >> 1));

        rtc1_write(ETIMEHREG, (uint16_t)(sec >> 17));

        spin_unlock_irq(&rtc_lock);

}

static void vr41xx_rtc_release(struct device *dev)

{

        spin_lock_irq(&rtc_lock);

        rtc1_write(ECMPLREG, 0);

        rtc1_write(ECMPMREG, 0);

        rtc1_write(ECMPHREG, 0);

        rtc1_write(RTCL1LREG, 0);

        rtc1_write(RTCL1HREG, 0);

        spin_unlock_irq(&rtc_lock);

        disable_irq(aie_irq);

        disable_irq(pie_irq);

}

static int vr41xx_rtc_read_time(struct device *dev, struct rtc_time *time)

{

        unsigned long epoch_sec, elapsed_sec;

        epoch_sec = mktime(epoch, 1, 1, 0, 0, 0);

        elapsed_sec = read_elapsed_second();

        rtc_time_to_tm(epoch_sec + elapsed_sec, time);

        return 0;

}

static int vr41xx_rtc_set_time(struct device *dev, struct rtc_time *time)

{

        unsigned long epoch_sec, current_sec;

        epoch_sec = mktime(epoch, 1, 1, 0, 0, 0);

        current_sec = mktime(time->tm_year + 1900, time->tm_mon + 1, time->tm_mday,

                             time->tm_hour, time->tm_min, time->tm_sec);

        write_elapsed_second(current_sec - epoch_sec);

        return 0;

}

static int vr41xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)

{

        unsigned long low, mid, high;

        struct rtc_time *time = &wkalrm->time;

        spin_lock_irq(&rtc_lock);

        low = rtc1_read(ECMPLREG);

        mid = rtc1_read(ECMPMREG);

        high = rtc1_read(ECMPHREG);

        wkalrm->enabled = alarm_enabled;

        spin_unlock_irq(&rtc_lock);

        rtc_time_to_tm((high << 17) | (mid << 1) | (low >> 15), time);

        return 0;

}

static int vr41xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)

{

        unsigned long alarm_sec;

        struct rtc_time *time = &wkalrm->time;

        alarm_sec = mktime(time->tm_year + 1900, time->tm_mon + 1, time->tm_mday,

                           time->tm_hour, time->tm_min, time->tm_sec);

        spin_lock_irq(&rtc_lock);

        if (alarm_enabled)

                disable_irq(aie_irq);

        rtc1_write(ECMPLREG, (uint16_t)(alarm_sec << 15));

        rtc1_write(ECMPMREG, (uint16_t)(alarm_sec >> 1));

        rtc1_write(ECMPHREG, (uint16_t)(alarm_sec >> 17));

        if (wkalrm->enabled)

                enable_irq(aie_irq);

        alarm_enabled = wkalrm->enabled;

        spin_unlock_irq(&rtc_lock);

        return 0;

}

static int vr41xx_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)

{

        unsigned long count;

        switch (cmd) {

        case RTC_AIE_ON:

                spin_lock_irq(&rtc_lock);

                if (!alarm_enabled) {

                        enable_irq(aie_irq);

                        alarm_enabled = 1;

                }

                spin_unlock_irq(&rtc_lock);

                break;

        case RTC_AIE_OFF:

                spin_lock_irq(&rtc_lock);

                if (alarm_enabled) {

                        disable_irq(aie_irq);

                        alarm_enabled = 0;

                }

                spin_unlock_irq(&rtc_lock);

                break;

        case RTC_PIE_ON:

                enable_irq(pie_irq);

                break;

        case RTC_PIE_OFF:

                disable_irq(pie_irq);

                break;

        case RTC_IRQP_READ:

                return put_user(periodic_frequency, (unsigned long __user *)arg);

                break;

        case RTC_IRQP_SET:

                if (arg > MAX_PERIODIC_RATE)

                        return -EINVAL;

                periodic_frequency = arg;

                count = RTC_FREQUENCY;

                do_div(count, arg);

                periodic_count = count;

                spin_lock_irq(&rtc_lock);

                rtc1_write(RTCL1LREG, count);

                rtc1_write(RTCL1HREG, count >> 16);

                spin_unlock_irq(&rtc_lock);

                break;

        case RTC_EPOCH_READ:

                return put_user(epoch, (unsigned long __user *)arg);

        case RTC_EPOCH_SET:

                /* Doesn't support before 1900 */

                if (arg < 1900)

                        return -EINVAL;

                epoch = arg;

                break;

        default:

                return -ENOIOCTLCMD;

        }

        return 0;

}

static irqreturn_t elapsedtime_interrupt(int irq, void *dev_id)

{

        struct platform_device *pdev = (struct platform_device *)dev_id;

        struct rtc_device *rtc = platform_get_drvdata(pdev);

        rtc2_write(RTCINTREG, ELAPSEDTIME_INT);

        rtc_update_irq(rtc, 1, RTC_AF);

        return IRQ_HANDLED;

}

static irqreturn_t rtclong1_interrupt(int irq, void *dev_id)

{

        struct platform_device *pdev = (struct platform_device *)dev_id;

        struct rtc_device *rtc = platform_get_drvdata(pdev);

        unsigned long count = periodic_count;

        rtc2_write(RTCINTREG, RTCLONG1_INT);

        rtc1_write(RTCL1LREG, count);

        rtc1_write(RTCL1HREG, count >> 16);

        rtc_update_irq(rtc, 1, RTC_PF);

        return IRQ_HANDLED;

}

static const struct rtc_class_ops vr41xx_rtc_ops = {

        .release        = vr41xx_rtc_release,

        .ioctl          = vr41xx_rtc_ioctl,

        .read_time      = vr41xx_rtc_read_time,

        .set_time       = vr41xx_rtc_set_time,

        .read_alarm     = vr41xx_rtc_read_alarm,

        .set_alarm      = vr41xx_rtc_set_alarm,

};

static int __devinit rtc_probe(struct platform_device *pdev)

{

        struct resource *res;

        struct rtc_device *rtc;

        int retval;

        if (pdev->num_resources != 4)

                return -EBUSY;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        if (!res)

                return -EBUSY;

        rtc1_base = ioremap(res->start, res->end - res->start + 1);

        if (!rtc1_base)

                return -EBUSY;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);

        if (!res) {

                retval = -EBUSY;

                goto err_rtc1_iounmap;

        }

        rtc2_base = ioremap(res->start, res->end - res->start + 1);

        if (!rtc2_base) {

                retval = -EBUSY;

                goto err_rtc1_iounmap;

        }

        rtc = rtc_device_register(rtc_name, &pdev->dev, &vr41xx_rtc_ops, THIS_MODULE);

        if (IS_ERR(rtc)) {

                retval = PTR_ERR(rtc);

                goto err_iounmap_all;

        }

        spin_lock_irq(&rtc_lock);

        rtc1_write(ECMPLREG, 0);

        rtc1_write(ECMPMREG, 0);

        rtc1_write(ECMPHREG, 0);

        rtc1_write(RTCL1LREG, 0);

        rtc1_write(RTCL1HREG, 0);

        spin_unlock_irq(&rtc_lock);

        aie_irq = platform_get_irq(pdev, 0);

        if (aie_irq < 0 || aie_irq >= NR_IRQS) {

                retval = -EBUSY;

                goto err_device_unregister;

        }

        retval = request_irq(aie_irq, elapsedtime_interrupt, IRQF_DISABLED,

                             "elapsed_time", pdev);

        if (retval < 0)

                goto err_device_unregister;

        pie_irq = platform_get_irq(pdev, 1);

        if (pie_irq < 0 || pie_irq >= NR_IRQS)

                goto err_free_irq;

        retval = request_irq(pie_irq, rtclong1_interrupt, IRQF_DISABLED,

                             "rtclong1", pdev);

        if (retval < 0)

                goto err_free_irq;

        platform_set_drvdata(pdev, rtc);

        disable_irq(aie_irq);

        disable_irq(pie_irq);

        printk(KERN_INFO "rtc: Real Time Clock of NEC VR4100 series\n");

        return 0;

err_free_irq:

        free_irq(aie_irq, pdev);

err_device_unregister:

        rtc_device_unregister(rtc);

err_iounmap_all:

        iounmap(rtc2_base);

        rtc2_base = NULL;

err_rtc1_iounmap:

        iounmap(rtc1_base);

        rtc1_base = NULL;

        return retval;

}

static int __devexit rtc_remove(struct platform_device *pdev)

{

        struct rtc_device *rtc;

        rtc = platform_get_drvdata(pdev);

        if (rtc)

                rtc_device_unregister(rtc);

        platform_set_drvdata(pdev, NULL);

        free_irq(aie_irq, pdev);

        free_irq(pie_irq, pdev);

        if (rtc1_base)

                iounmap(rtc1_base);

        if (rtc2_base)

                iounmap(rtc2_base);

        return 0;

}

static struct platform_driver rtc_platform_driver = {

        .probe          = rtc_probe,

        .remove         = __devexit_p(rtc_remove),

        .driver         = {

                .name   = rtc_name,

                .owner  = THIS_MODULE,

        },

};

static int __init vr41xx_rtc_init(void)

{

        return platform_driver_register(&rtc_platform_driver);

}

static void __exit vr41xx_rtc_exit(void)

{

        platform_driver_unregister(&rtc_platform_driver);

}

module_init(vr41xx_rtc_init);

module_exit(vr41xx_rtc_exit);