drivers/rtc/rtc-ds1553.c - maze/linux - Git at Google

 /*
  * An rtc driver for the Dallas DS1553
  *
  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
  *
  * 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/bcd.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/jiffies.h>
 #include <linux/interrupt.h>
 #include <linux/rtc.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>

 #define DRV_VERSION "0.2"

 #define RTC_REG_SIZE		0x2000
 #define RTC_OFFSET		0x1ff0

 #define RTC_FLAGS		(RTC_OFFSET + 0)
 #define RTC_SECONDS_ALARM	(RTC_OFFSET + 2)
 #define RTC_MINUTES_ALARM	(RTC_OFFSET + 3)
 #define RTC_HOURS_ALARM		(RTC_OFFSET + 4)
 #define RTC_DATE_ALARM		(RTC_OFFSET + 5)
 #define RTC_INTERRUPTS		(RTC_OFFSET + 6)
 #define RTC_WATCHDOG		(RTC_OFFSET + 7)
 #define RTC_CONTROL		(RTC_OFFSET + 8)
 #define RTC_CENTURY		(RTC_OFFSET + 8)
 #define RTC_SECONDS		(RTC_OFFSET + 9)
 #define RTC_MINUTES		(RTC_OFFSET + 10)
 #define RTC_HOURS		(RTC_OFFSET + 11)
 #define RTC_DAY			(RTC_OFFSET + 12)
 #define RTC_DATE		(RTC_OFFSET + 13)
 #define RTC_MONTH		(RTC_OFFSET + 14)
 #define RTC_YEAR		(RTC_OFFSET + 15)

 #define RTC_CENTURY_MASK	0x3f
 #define RTC_SECONDS_MASK	0x7f
 #define RTC_DAY_MASK		0x07

 /* Bits in the Control/Century register */
 #define RTC_WRITE		0x80
 #define RTC_READ		0x40

 /* Bits in the Seconds register */
 #define RTC_STOP		0x80

 /* Bits in the Flags register */
 #define RTC_FLAGS_AF		0x40
 #define RTC_FLAGS_BLF		0x10

 /* Bits in the Interrupts register */
 #define RTC_INTS_AE		0x80

 struct rtc_plat_data {
 	struct rtc_device *rtc;
 	void __iomem *ioaddr;
 	unsigned long baseaddr;
 	unsigned long last_jiffies;
 	int irq;
 	unsigned int irqen;
 	int alrm_sec;
 	int alrm_min;
 	int alrm_hour;
 	int alrm_mday;
 };

 static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	u8 century;

 	century = BIN2BCD((tm->tm_year + 1900) / 100);

 	writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);

 	writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR);
 	writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH);
 	writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
 	writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE);
 	writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS);
 	writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES);
 	writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);

 	/* RTC_CENTURY and RTC_CONTROL share same register */
 	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
 	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 	return 0;
 }

 static int ds1553_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	unsigned int year, month, day, hour, minute, second, week;
 	unsigned int century;

 	/* give enough time to update RTC in case of continuous read */
 	if (pdata->last_jiffies == jiffies)
 		msleep(1);
 	pdata->last_jiffies = jiffies;
 	writeb(RTC_READ, ioaddr + RTC_CONTROL);
 	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 	minute = readb(ioaddr + RTC_MINUTES);
 	hour = readb(ioaddr + RTC_HOURS);
 	day = readb(ioaddr + RTC_DATE);
 	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 	month = readb(ioaddr + RTC_MONTH);
 	year = readb(ioaddr + RTC_YEAR);
 	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 	writeb(0, ioaddr + RTC_CONTROL);
 	tm->tm_sec = BCD2BIN(second);
 	tm->tm_min = BCD2BIN(minute);
 	tm->tm_hour = BCD2BIN(hour);
 	tm->tm_mday = BCD2BIN(day);
 	tm->tm_wday = BCD2BIN(week);
 	tm->tm_mon = BCD2BIN(month) - 1;
 	/* year is 1900 + tm->tm_year */
 	tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900;

 	if (rtc_valid_tm(tm) < 0) {
 		dev_err(dev, "retrieved date/time is not valid.\n");
 		rtc_time_to_tm(0, tm);
 	}
 	return 0;
 }

 static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
 {
 	void __iomem *ioaddr = pdata->ioaddr;
 	unsigned long flags;

 	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
 	writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
 	       0x80 : BIN2BCD(pdata->alrm_mday),
 	       ioaddr + RTC_DATE_ALARM);
 	writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
 	       0x80 : BIN2BCD(pdata->alrm_hour),
 	       ioaddr + RTC_HOURS_ALARM);
 	writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
 	       0x80 : BIN2BCD(pdata->alrm_min),
 	       ioaddr + RTC_MINUTES_ALARM);
 	writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
 	       0x80 : BIN2BCD(pdata->alrm_sec),
 	       ioaddr + RTC_SECONDS_ALARM);
 	writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
 	readb(ioaddr + RTC_FLAGS);	/* clear interrupts */
 	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
 }

 static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

 	if (pdata->irq < 0)
 		return -EINVAL;
 	pdata->alrm_mday = alrm->time.tm_mday;
 	pdata->alrm_hour = alrm->time.tm_hour;
 	pdata->alrm_min = alrm->time.tm_min;
 	pdata->alrm_sec = alrm->time.tm_sec;
 	if (alrm->enabled)
 		pdata->irqen |= RTC_AF;
 	ds1553_rtc_update_alarm(pdata);
 	return 0;
 }

 static int ds1553_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

 	if (pdata->irq < 0)
 		return -EINVAL;
 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
 	return 0;
 }

 static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
 {
 	struct platform_device *pdev = dev_id;
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	unsigned long events = RTC_IRQF;

 	/* read and clear interrupt */
 	if (!(readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF))
 		return IRQ_NONE;
 	if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
 		events |= RTC_UF;
 	else
 		events |= RTC_AF;
 	rtc_update_irq(&pdata->rtc->class_dev, 1, events);
 	return IRQ_HANDLED;
 }

 static void ds1553_rtc_release(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

 	if (pdata->irq >= 0) {
 		pdata->irqen = 0;
 		ds1553_rtc_update_alarm(pdata);
 	}
 }

 static int ds1553_rtc_ioctl(struct device *dev, unsigned int cmd,
 			    unsigned long arg)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

 	if (pdata->irq < 0)
 		return -ENOIOCTLCMD; /* fall back into rtc-dev's emulation */
 	switch (cmd) {
 	case RTC_AIE_OFF:
 		pdata->irqen &= ~RTC_AF;
 		ds1553_rtc_update_alarm(pdata);
 		break;
 	case RTC_AIE_ON:
 		pdata->irqen |= RTC_AF;
 		ds1553_rtc_update_alarm(pdata);
 		break;
 	case RTC_UIE_OFF:
 		pdata->irqen &= ~RTC_UF;
 		ds1553_rtc_update_alarm(pdata);
 		break;
 	case RTC_UIE_ON:
 		pdata->irqen |= RTC_UF;
 		ds1553_rtc_update_alarm(pdata);
 		break;
 	default:
 		return -ENOIOCTLCMD;
 	}
 	return 0;
 }

 static const struct rtc_class_ops ds1553_rtc_ops = {
 	.read_time	= ds1553_rtc_read_time,
 	.set_time	= ds1553_rtc_set_time,
 	.read_alarm	= ds1553_rtc_read_alarm,
 	.set_alarm	= ds1553_rtc_set_alarm,
 	.release	= ds1553_rtc_release,
 	.ioctl		= ds1553_rtc_ioctl,
 };

 static ssize_t ds1553_nvram_read(struct kobject *kobj, char *buf,
 				 loff_t pos, size_t size)
 {
 	struct platform_device *pdev =
 		to_platform_device(container_of(kobj, struct device, kobj));
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	ssize_t count;

 	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
 		*buf++ = readb(ioaddr + pos++);
 	return count;
 }

 static ssize_t ds1553_nvram_write(struct kobject *kobj, char *buf,
 				  loff_t pos, size_t size)
 {
 	struct platform_device *pdev =
 		to_platform_device(container_of(kobj, struct device, kobj));
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	ssize_t count;

 	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
 		writeb(*buf++, ioaddr + pos++);
 	return count;
 }

 static struct bin_attribute ds1553_nvram_attr = {
 	.attr = {
 		.name = "nvram",
 		.mode = S_IRUGO | S_IWUGO,
 		.owner = THIS_MODULE,
 	},
 	.size = RTC_OFFSET,
 	.read = ds1553_nvram_read,
 	.write = ds1553_nvram_write,
 };

 static int __init ds1553_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 	struct resource *res;
 	unsigned int cen, sec;
 	struct rtc_plat_data *pdata = NULL;
 	void __iomem *ioaddr = NULL;
 	int ret = 0;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)
 		return -ENODEV;
 	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return -ENOMEM;
 	pdata->irq = -1;
 	if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
 		ret = -EBUSY;
 		goto out;
 	}
 	pdata->baseaddr = res->start;
 	ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
 	if (!ioaddr) {
 		ret = -ENOMEM;
 		goto out;
 	}
 	pdata->ioaddr = ioaddr;
 	pdata->irq = platform_get_irq(pdev, 0);

 	/* turn RTC on if it was not on */
 	sec = readb(ioaddr + RTC_SECONDS);
 	if (sec & RTC_STOP) {
 		sec &= RTC_SECONDS_MASK;
 		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 		writeb(sec, ioaddr + RTC_SECONDS);
 		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 	}
 	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
 		dev_warn(&pdev->dev, "voltage-low detected.\n");

 	if (pdata->irq >= 0) {
 		writeb(0, ioaddr + RTC_INTERRUPTS);
 		if (request_irq(pdata->irq, ds1553_rtc_interrupt,
 				IRQF_DISABLED | IRQF_SHARED,
 				pdev->name, pdev) < 0) {
 			dev_warn(&pdev->dev, "interrupt not available.\n");
 			pdata->irq = -1;
 		}
 	}

 	rtc = rtc_device_register(pdev->name, &pdev->dev,
 				  &ds1553_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc)) {
 		ret = PTR_ERR(rtc);
 		goto out;
 	}
 	pdata->rtc = rtc;
 	pdata->last_jiffies = jiffies;
 	platform_set_drvdata(pdev, pdata);
 	ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
 	if (ret)
 		goto out;
 	return 0;
  out:
 	if (pdata->rtc)
 		rtc_device_unregister(pdata->rtc);
 	if (pdata->irq >= 0)
 		free_irq(pdata->irq, pdev);
 	if (ioaddr)
 		iounmap(ioaddr);
 	if (pdata->baseaddr)
 		release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
 	kfree(pdata);
 	return ret;
 }

 static int __devexit ds1553_rtc_remove(struct platform_device *pdev)
 {
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

 	sysfs_remove_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
 	rtc_device_unregister(pdata->rtc);
 	if (pdata->irq >= 0) {
 		writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
 		free_irq(pdata->irq, pdev);
 	}
 	iounmap(pdata->ioaddr);
 	release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
 	kfree(pdata);
 	return 0;
 }

 static struct platform_driver ds1553_rtc_driver = {
 	.probe		= ds1553_rtc_probe,
 	.remove		= __devexit_p(ds1553_rtc_remove),
 	.driver		= {
 		.name	= "ds1553",
 		.owner	= THIS_MODULE,
 	},
 };

 static __init int ds1553_init(void)
 {
 	return platform_driver_register(&ds1553_rtc_driver);
 }

 static __exit void ds1553_exit(void)
 {
 	return platform_driver_unregister(&ds1553_rtc_driver);
 }

 module_init(ds1553_init);
 module_exit(ds1553_exit);

 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);
	/*
	* An rtc driver for the Dallas DS1553
	*
	* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
	*
	* 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/bcd.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/delay.h>
	#include <linux/jiffies.h>
	#include <linux/interrupt.h>
	#include <linux/rtc.h>
	#include <linux/platform_device.h>
	#include <linux/io.h>

	#define DRV_VERSION "0.2"

	#define RTC_REG_SIZE 0x2000
	#define RTC_OFFSET 0x1ff0

	#define RTC_FLAGS (RTC_OFFSET + 0)
	#define RTC_SECONDS_ALARM (RTC_OFFSET + 2)
	#define RTC_MINUTES_ALARM (RTC_OFFSET + 3)
	#define RTC_HOURS_ALARM (RTC_OFFSET + 4)
	#define RTC_DATE_ALARM (RTC_OFFSET + 5)
	#define RTC_INTERRUPTS (RTC_OFFSET + 6)
	#define RTC_WATCHDOG (RTC_OFFSET + 7)
	#define RTC_CONTROL (RTC_OFFSET + 8)
	#define RTC_CENTURY (RTC_OFFSET + 8)
	#define RTC_SECONDS (RTC_OFFSET + 9)
	#define RTC_MINUTES (RTC_OFFSET + 10)
	#define RTC_HOURS (RTC_OFFSET + 11)
	#define RTC_DAY (RTC_OFFSET + 12)
	#define RTC_DATE (RTC_OFFSET + 13)
	#define RTC_MONTH (RTC_OFFSET + 14)
	#define RTC_YEAR (RTC_OFFSET + 15)

	#define RTC_CENTURY_MASK 0x3f
	#define RTC_SECONDS_MASK 0x7f
	#define RTC_DAY_MASK 0x07

	/* Bits in the Control/Century register */
	#define RTC_WRITE 0x80
	#define RTC_READ 0x40

	/* Bits in the Seconds register */
	#define RTC_STOP 0x80

	/* Bits in the Flags register */
	#define RTC_FLAGS_AF 0x40
	#define RTC_FLAGS_BLF 0x10

	/* Bits in the Interrupts register */
	#define RTC_INTS_AE 0x80

	struct rtc_plat_data {
	struct rtc_device *rtc;
	void __iomem *ioaddr;
	unsigned long baseaddr;
	unsigned long last_jiffies;
	int irq;
	unsigned int irqen;
	int alrm_sec;
	int alrm_min;
	int alrm_hour;
	int alrm_mday;
	};

	static int ds1553_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
	void __iomem *ioaddr = pdata->ioaddr;
	u8 century;

	century = BIN2BCD((tm->tm_year + 1900) / 100);

	writeb(RTC_WRITE, pdata->ioaddr + RTC_CONTROL);

	writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR);
	writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH);
	writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
	writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE);
	writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS);
	writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES);
	writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);

	/* RTC_CENTURY and RTC_CONTROL share same register */
	writeb(RTC_WRITE \| (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
	return 0;
	}

	static int ds1553_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
	void __iomem *ioaddr = pdata->ioaddr;
	unsigned int year, month, day, hour, minute, second, week;
	unsigned int century;

	/* give enough time to update RTC in case of continuous read */
	if (pdata->last_jiffies == jiffies)
	msleep(1);
	pdata->last_jiffies = jiffies;
	writeb(RTC_READ, ioaddr + RTC_CONTROL);
	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
	minute = readb(ioaddr + RTC_MINUTES);
	hour = readb(ioaddr + RTC_HOURS);
	day = readb(ioaddr + RTC_DATE);
	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
	month = readb(ioaddr + RTC_MONTH);
	year = readb(ioaddr + RTC_YEAR);
	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
	writeb(0, ioaddr + RTC_CONTROL);
	tm->tm_sec = BCD2BIN(second);
	tm->tm_min = BCD2BIN(minute);
	tm->tm_hour = BCD2BIN(hour);
	tm->tm_mday = BCD2BIN(day);
	tm->tm_wday = BCD2BIN(week);
	tm->tm_mon = BCD2BIN(month) - 1;
	/* year is 1900 + tm->tm_year */
	tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900;

	if (rtc_valid_tm(tm) < 0) {
	dev_err(dev, "retrieved date/time is not valid.\n");
	rtc_time_to_tm(0, tm);
	}
	return 0;
	}

	static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
	{
	void __iomem *ioaddr = pdata->ioaddr;
	unsigned long flags;

	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
	writeb(pdata->alrm_mday < 0 \|\| (pdata->irqen & RTC_UF) ?
	0x80 : BIN2BCD(pdata->alrm_mday),
	ioaddr + RTC_DATE_ALARM);
	writeb(pdata->alrm_hour < 0 \|\| (pdata->irqen & RTC_UF) ?
	0x80 : BIN2BCD(pdata->alrm_hour),
	ioaddr + RTC_HOURS_ALARM);
	writeb(pdata->alrm_min < 0 \|\| (pdata->irqen & RTC_UF) ?
	0x80 : BIN2BCD(pdata->alrm_min),
	ioaddr + RTC_MINUTES_ALARM);
	writeb(pdata->alrm_sec < 0 \|\| (pdata->irqen & RTC_UF) ?
	0x80 : BIN2BCD(pdata->alrm_sec),
	ioaddr + RTC_SECONDS_ALARM);
	writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
	readb(ioaddr + RTC_FLAGS); /* clear interrupts */
	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
	}

	static int ds1553_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

	if (pdata->irq < 0)
	return -EINVAL;
	pdata->alrm_mday = alrm->time.tm_mday;
	pdata->alrm_hour = alrm->time.tm_hour;
	pdata->alrm_min = alrm->time.tm_min;
	pdata->alrm_sec = alrm->time.tm_sec;
	if (alrm->enabled)
	pdata->irqen \|= RTC_AF;
	ds1553_rtc_update_alarm(pdata);
	return 0;
	}

	static int ds1553_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

	if (pdata->irq < 0)
	return -EINVAL;
	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
	return 0;
	}

	static irqreturn_t ds1553_rtc_interrupt(int irq, void *dev_id)
	{
	struct platform_device *pdev = dev_id;
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
	void __iomem *ioaddr = pdata->ioaddr;
	unsigned long events = RTC_IRQF;

	/* read and clear interrupt */
	if (!(readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF))
	return IRQ_NONE;
	if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
	events \|= RTC_UF;
	else
	events \|= RTC_AF;
	rtc_update_irq(&pdata->rtc->class_dev, 1, events);
	return IRQ_HANDLED;
	}

	static void ds1553_rtc_release(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

	if (pdata->irq >= 0) {
	pdata->irqen = 0;
	ds1553_rtc_update_alarm(pdata);
	}
	}

	static int ds1553_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

	if (pdata->irq < 0)
	return -ENOIOCTLCMD; /* fall back into rtc-dev's emulation */
	switch (cmd) {
	case RTC_AIE_OFF:
	pdata->irqen &= ~RTC_AF;
	ds1553_rtc_update_alarm(pdata);
	break;
	case RTC_AIE_ON:
	pdata->irqen \|= RTC_AF;
	ds1553_rtc_update_alarm(pdata);
	break;
	case RTC_UIE_OFF:
	pdata->irqen &= ~RTC_UF;
	ds1553_rtc_update_alarm(pdata);
	break;
	case RTC_UIE_ON:
	pdata->irqen \|= RTC_UF;
	ds1553_rtc_update_alarm(pdata);
	break;
	default:
	return -ENOIOCTLCMD;
	}
	return 0;
	}

	static const struct rtc_class_ops ds1553_rtc_ops = {
	.read_time = ds1553_rtc_read_time,
	.set_time = ds1553_rtc_set_time,
	.read_alarm = ds1553_rtc_read_alarm,
	.set_alarm = ds1553_rtc_set_alarm,
	.release = ds1553_rtc_release,
	.ioctl = ds1553_rtc_ioctl,
	};

	static ssize_t ds1553_nvram_read(struct kobject kobj, char buf,
	loff_t pos, size_t size)
	{
	struct platform_device *pdev =
	to_platform_device(container_of(kobj, struct device, kobj));
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
	void __iomem *ioaddr = pdata->ioaddr;
	ssize_t count;

	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
	*buf++ = readb(ioaddr + pos++);
	return count;
	}

	static ssize_t ds1553_nvram_write(struct kobject kobj, char buf,
	loff_t pos, size_t size)
	{
	struct platform_device *pdev =
	to_platform_device(container_of(kobj, struct device, kobj));
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
	void __iomem *ioaddr = pdata->ioaddr;
	ssize_t count;

	for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
	writeb(*buf++, ioaddr + pos++);
	return count;
	}

	static struct bin_attribute ds1553_nvram_attr = {
	.attr = {
	.name = "nvram",
	.mode = S_IRUGO \| S_IWUGO,
	.owner = THIS_MODULE,
	},
	.size = RTC_OFFSET,
	.read = ds1553_nvram_read,
	.write = ds1553_nvram_write,
	};

	static int __init ds1553_rtc_probe(struct platform_device *pdev)
	{
	struct rtc_device *rtc;
	struct resource *res;
	unsigned int cen, sec;
	struct rtc_plat_data *pdata = NULL;
	void __iomem *ioaddr = NULL;
	int ret = 0;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
	return -ENODEV;
	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
	return -ENOMEM;
	pdata->irq = -1;
	if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
	ret = -EBUSY;
	goto out;
	}
	pdata->baseaddr = res->start;
	ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
	if (!ioaddr) {
	ret = -ENOMEM;
	goto out;
	}
	pdata->ioaddr = ioaddr;
	pdata->irq = platform_get_irq(pdev, 0);

	/* turn RTC on if it was not on */
	sec = readb(ioaddr + RTC_SECONDS);
	if (sec & RTC_STOP) {
	sec &= RTC_SECONDS_MASK;
	cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
	writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
	writeb(sec, ioaddr + RTC_SECONDS);
	writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
	}
	if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
	dev_warn(&pdev->dev, "voltage-low detected.\n");

	if (pdata->irq >= 0) {
	writeb(0, ioaddr + RTC_INTERRUPTS);
	if (request_irq(pdata->irq, ds1553_rtc_interrupt,
	IRQF_DISABLED \| IRQF_SHARED,
	pdev->name, pdev) < 0) {
	dev_warn(&pdev->dev, "interrupt not available.\n");
	pdata->irq = -1;
	}
	}

	rtc = rtc_device_register(pdev->name, &pdev->dev,
	&ds1553_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc)) {
	ret = PTR_ERR(rtc);
	goto out;
	}
	pdata->rtc = rtc;
	pdata->last_jiffies = jiffies;
	platform_set_drvdata(pdev, pdata);
	ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
	if (ret)
	goto out;
	return 0;
	out:
	if (pdata->rtc)
	rtc_device_unregister(pdata->rtc);
	if (pdata->irq >= 0)
	free_irq(pdata->irq, pdev);
	if (ioaddr)
	iounmap(ioaddr);
	if (pdata->baseaddr)
	release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
	kfree(pdata);
	return ret;
	}

	static int __devexit ds1553_rtc_remove(struct platform_device *pdev)
	{
	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

	sysfs_remove_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
	rtc_device_unregister(pdata->rtc);
	if (pdata->irq >= 0) {
	writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
	free_irq(pdata->irq, pdev);
	}
	iounmap(pdata->ioaddr);
	release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
	kfree(pdata);
	return 0;
	}

	static struct platform_driver ds1553_rtc_driver = {
	.probe = ds1553_rtc_probe,
	.remove = __devexit_p(ds1553_rtc_remove),
	.driver = {
	.name = "ds1553",
	.owner = THIS_MODULE,
	},
	};

	static __init int ds1553_init(void)
	{
	return platform_driver_register(&ds1553_rtc_driver);
	}

	static __exit void ds1553_exit(void)
	{
	return platform_driver_unregister(&ds1553_rtc_driver);
	}

	module_init(ds1553_init);
	module_exit(ds1553_exit);

	MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
	MODULE_DESCRIPTION("Dallas DS1553 RTC driver");
	MODULE_LICENSE("GPL");
	MODULE_VERSION(DRV_VERSION);