drivers/rtc/rtc-vt8500.c - linux - Git at Google

 /*
  * drivers/rtc/rtc-vt8500.c
  *
  *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
  *
  * Based on rtc-pxa.c
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * 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.
  */

 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/bcd.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/of.h>

 /*
  * Register definitions
  */
 #define VT8500_RTC_TS		0x00	/* Time set */
 #define VT8500_RTC_DS		0x04	/* Date set */
 #define VT8500_RTC_AS		0x08	/* Alarm set */
 #define VT8500_RTC_CR		0x0c	/* Control */
 #define VT8500_RTC_TR		0x10	/* Time read */
 #define VT8500_RTC_DR		0x14	/* Date read */
 #define VT8500_RTC_WS		0x18	/* Write status */
 #define VT8500_RTC_CL		0x20	/* Calibration */
 #define VT8500_RTC_IS		0x24	/* Interrupt status */
 #define VT8500_RTC_ST		0x28	/* Status */

 #define INVALID_TIME_BIT	(1 << 31)

 #define DATE_CENTURY_S		19
 #define DATE_YEAR_S		11
 #define DATE_YEAR_MASK		(0xff << DATE_YEAR_S)
 #define DATE_MONTH_S		6
 #define DATE_MONTH_MASK		(0x1f << DATE_MONTH_S)
 #define DATE_DAY_MASK		0x3f

 #define TIME_DOW_S		20
 #define TIME_DOW_MASK		(0x07 << TIME_DOW_S)
 #define TIME_HOUR_S		14
 #define TIME_HOUR_MASK		(0x3f << TIME_HOUR_S)
 #define TIME_MIN_S		7
 #define TIME_MIN_MASK		(0x7f << TIME_MIN_S)
 #define TIME_SEC_MASK		0x7f

 #define ALARM_DAY_S		20
 #define ALARM_DAY_MASK		(0x3f << ALARM_DAY_S)

 #define ALARM_DAY_BIT		(1 << 29)
 #define ALARM_HOUR_BIT		(1 << 28)
 #define ALARM_MIN_BIT		(1 << 27)
 #define ALARM_SEC_BIT		(1 << 26)

 #define ALARM_ENABLE_MASK	(ALARM_DAY_BIT \
 				| ALARM_HOUR_BIT \
 				| ALARM_MIN_BIT \
 				| ALARM_SEC_BIT)

 #define VT8500_RTC_CR_ENABLE	(1 << 0)	/* Enable RTC */
 #define VT8500_RTC_CR_24H	(1 << 1)	/* 24h time format */
 #define VT8500_RTC_CR_SM_ENABLE	(1 << 2)	/* Enable periodic irqs */
 #define VT8500_RTC_CR_SM_SEC	(1 << 3)	/* 0: 1Hz/60, 1: 1Hz */
 #define VT8500_RTC_CR_CALIB	(1 << 4)	/* Enable calibration */

 #define VT8500_RTC_IS_ALARM	(1 << 0)	/* Alarm interrupt status */

 struct vt8500_rtc {
 	void __iomem		*regbase;
 	struct resource		*res;
 	int			irq_alarm;
 	struct rtc_device	*rtc;
 	spinlock_t		lock;		/* Protects this structure */
 };

 static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_id;
 	u32 isr;
 	unsigned long events = 0;

 	spin_lock(&vt8500_rtc->lock);

 	/* clear interrupt sources */
 	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
 	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);

 	spin_unlock(&vt8500_rtc->lock);

 	if (isr & VT8500_RTC_IS_ALARM)
 		events |= RTC_AF | RTC_IRQF;

 	rtc_update_irq(vt8500_rtc->rtc, 1, events);

 	return IRQ_HANDLED;
 }

 static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
 	u32 date, time;

 	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
 	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);

 	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
 	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
 	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
 	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
 	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
 	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
 			+ ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
 	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;

 	return 0;
 }

 static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

 	if (tm->tm_year < 100) {
 		dev_warn(dev, "Only years 2000-2199 are supported by the "
 			      "hardware!\n");
 		return -EINVAL;
 	}

 	writel((bin2bcd(tm->tm_year - 100) << DATE_YEAR_S)
 		| (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
 		| (bin2bcd(tm->tm_mday)),
 		vt8500_rtc->regbase + VT8500_RTC_DS);
 	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
 		| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
 		| (bin2bcd(tm->tm_min) << TIME_MIN_S)
 		| (bin2bcd(tm->tm_sec)),
 		vt8500_rtc->regbase + VT8500_RTC_TS);

 	return 0;
 }

 static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
 	u32 isr, alarm;

 	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
 	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);

 	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
 	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
 	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
 	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));

 	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
 	alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;

 	return rtc_valid_tm(&alrm->time);
 }

 static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

 	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
 		| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
 		| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
 		| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
 		| (bin2bcd(alrm->time.tm_sec)),
 		vt8500_rtc->regbase + VT8500_RTC_AS);

 	return 0;
 }

 static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
 	unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);

 	if (enabled)
 		tmp |= ALARM_ENABLE_MASK;
 	else
 		tmp &= ~ALARM_ENABLE_MASK;

 	writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
 	return 0;
 }

 static const struct rtc_class_ops vt8500_rtc_ops = {
 	.read_time = vt8500_rtc_read_time,
 	.set_time = vt8500_rtc_set_time,
 	.read_alarm = vt8500_rtc_read_alarm,
 	.set_alarm = vt8500_rtc_set_alarm,
 	.alarm_irq_enable = vt8500_alarm_irq_enable,
 };

 static int vt8500_rtc_probe(struct platform_device *pdev)
 {
 	struct vt8500_rtc *vt8500_rtc;
 	int ret;

 	vt8500_rtc = devm_kzalloc(&pdev->dev,
 			   sizeof(struct vt8500_rtc), GFP_KERNEL);
 	if (!vt8500_rtc)
 		return -ENOMEM;

 	spin_lock_init(&vt8500_rtc->lock);
 	platform_set_drvdata(pdev, vt8500_rtc);

 	vt8500_rtc->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!vt8500_rtc->res) {
 		dev_err(&pdev->dev, "No I/O memory resource defined\n");
 		return -ENXIO;
 	}

 	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
 	if (vt8500_rtc->irq_alarm < 0) {
 		dev_err(&pdev->dev, "No alarm IRQ resource defined\n");
 		return -ENXIO;
 	}

 	vt8500_rtc->res = request_mem_region(vt8500_rtc->res->start,
 					     resource_size(vt8500_rtc->res),
 					     "vt8500-rtc");
 	if (vt8500_rtc->res == NULL) {
 		dev_err(&pdev->dev, "failed to request I/O memory\n");
 		return -EBUSY;
 	}

 	vt8500_rtc->regbase = ioremap(vt8500_rtc->res->start,
 				      resource_size(vt8500_rtc->res));
 	if (!vt8500_rtc->regbase) {
 		dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
 		ret = -EBUSY;
 		goto err_release;
 	}

 	/* Enable RTC and set it to 24-hour mode */
 	writel(VT8500_RTC_CR_ENABLE | VT8500_RTC_CR_24H,
 	       vt8500_rtc->regbase + VT8500_RTC_CR);

 	vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
 					      &vt8500_rtc_ops, THIS_MODULE);
 	if (IS_ERR(vt8500_rtc->rtc)) {
 		ret = PTR_ERR(vt8500_rtc->rtc);
 		dev_err(&pdev->dev,
 			"Failed to register RTC device -> %d\n", ret);
 		goto err_unmap;
 	}

 	ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, 0,
 			  "rtc alarm", vt8500_rtc);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "can't get irq %i, err %d\n",
 			vt8500_rtc->irq_alarm, ret);
 		goto err_unreg;
 	}

 	return 0;

 err_unreg:
 	rtc_device_unregister(vt8500_rtc->rtc);
 err_unmap:
 	iounmap(vt8500_rtc->regbase);
 err_release:
 	release_mem_region(vt8500_rtc->res->start,
 			   resource_size(vt8500_rtc->res));
 	return ret;
 }

 static int vt8500_rtc_remove(struct platform_device *pdev)
 {
 	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);

 	free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);

 	rtc_device_unregister(vt8500_rtc->rtc);

 	/* Disable alarm matching */
 	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
 	iounmap(vt8500_rtc->regbase);
 	release_mem_region(vt8500_rtc->res->start,
 			   resource_size(vt8500_rtc->res));

 	platform_set_drvdata(pdev, NULL);

 	return 0;
 }

 static const struct of_device_id wmt_dt_ids[] = {
 	{ .compatible = "via,vt8500-rtc", },
 	{}
 };

 static struct platform_driver vt8500_rtc_driver = {
 	.probe		= vt8500_rtc_probe,
 	.remove		= vt8500_rtc_remove,
 	.driver		= {
 		.name	= "vt8500-rtc",
 		.owner	= THIS_MODULE,
 		.of_match_table = of_match_ptr(wmt_dt_ids),
 	},
 };

 module_platform_driver(vt8500_rtc_driver);

 MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
 MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:vt8500-rtc");
	/*
	* drivers/rtc/rtc-vt8500.c
	*
	* Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
	*
	* Based on rtc-pxa.c
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* 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.
	*/

	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/bcd.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/of.h>

	/*
	* Register definitions
	*/
	#define VT8500_RTC_TS 0x00 /* Time set */
	#define VT8500_RTC_DS 0x04 /* Date set */
	#define VT8500_RTC_AS 0x08 /* Alarm set */
	#define VT8500_RTC_CR 0x0c /* Control */
	#define VT8500_RTC_TR 0x10 /* Time read */
	#define VT8500_RTC_DR 0x14 /* Date read */
	#define VT8500_RTC_WS 0x18 /* Write status */
	#define VT8500_RTC_CL 0x20 /* Calibration */
	#define VT8500_RTC_IS 0x24 /* Interrupt status */
	#define VT8500_RTC_ST 0x28 /* Status */

	#define INVALID_TIME_BIT (1 << 31)

	#define DATE_CENTURY_S 19
	#define DATE_YEAR_S 11
	#define DATE_YEAR_MASK (0xff << DATE_YEAR_S)
	#define DATE_MONTH_S 6
	#define DATE_MONTH_MASK (0x1f << DATE_MONTH_S)
	#define DATE_DAY_MASK 0x3f

	#define TIME_DOW_S 20
	#define TIME_DOW_MASK (0x07 << TIME_DOW_S)
	#define TIME_HOUR_S 14
	#define TIME_HOUR_MASK (0x3f << TIME_HOUR_S)
	#define TIME_MIN_S 7
	#define TIME_MIN_MASK (0x7f << TIME_MIN_S)
	#define TIME_SEC_MASK 0x7f

	#define ALARM_DAY_S 20
	#define ALARM_DAY_MASK (0x3f << ALARM_DAY_S)

	#define ALARM_DAY_BIT (1 << 29)
	#define ALARM_HOUR_BIT (1 << 28)
	#define ALARM_MIN_BIT (1 << 27)
	#define ALARM_SEC_BIT (1 << 26)

	#define ALARM_ENABLE_MASK (ALARM_DAY_BIT \
	\| ALARM_HOUR_BIT \
	\| ALARM_MIN_BIT \
	\| ALARM_SEC_BIT)

	#define VT8500_RTC_CR_ENABLE (1 << 0) /* Enable RTC */
	#define VT8500_RTC_CR_24H (1 << 1) /* 24h time format */
	#define VT8500_RTC_CR_SM_ENABLE (1 << 2) /* Enable periodic irqs */
	#define VT8500_RTC_CR_SM_SEC (1 << 3) /* 0: 1Hz/60, 1: 1Hz */
	#define VT8500_RTC_CR_CALIB (1 << 4) /* Enable calibration */

	#define VT8500_RTC_IS_ALARM (1 << 0) /* Alarm interrupt status */

	struct vt8500_rtc {
	void __iomem *regbase;
	struct resource *res;
	int irq_alarm;
	struct rtc_device *rtc;
	spinlock_t lock; /* Protects this structure */
	};

	static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
	{
	struct vt8500_rtc *vt8500_rtc = dev_id;
	u32 isr;
	unsigned long events = 0;

	spin_lock(&vt8500_rtc->lock);

	/* clear interrupt sources */
	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);

	spin_unlock(&vt8500_rtc->lock);

	if (isr & VT8500_RTC_IS_ALARM)
	events \|= RTC_AF \| RTC_IRQF;

	rtc_update_irq(vt8500_rtc->rtc, 1, events);

	return IRQ_HANDLED;
	}

	static int vt8500_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
	u32 date, time;

	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);

	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
	+ ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;

	return 0;
	}

	static int vt8500_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

	if (tm->tm_year < 100) {
	dev_warn(dev, "Only years 2000-2199 are supported by the "
	"hardware!\n");
	return -EINVAL;
	}

	writel((bin2bcd(tm->tm_year - 100) << DATE_YEAR_S)
	\| (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
	\| (bin2bcd(tm->tm_mday)),
	vt8500_rtc->regbase + VT8500_RTC_DS);
	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
	\| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
	\| (bin2bcd(tm->tm_min) << TIME_MIN_S)
	\| (bin2bcd(tm->tm_sec)),
	vt8500_rtc->regbase + VT8500_RTC_TS);

	return 0;
	}

	static int vt8500_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
	u32 isr, alarm;

	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);

	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));

	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
	alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;

	return rtc_valid_tm(&alrm->time);
	}

	static int vt8500_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
	\| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
	\| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
	\| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
	\| (bin2bcd(alrm->time.tm_sec)),
	vt8500_rtc->regbase + VT8500_RTC_AS);

	return 0;
	}

	static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
	unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);

	if (enabled)
	tmp \|= ALARM_ENABLE_MASK;
	else
	tmp &= ~ALARM_ENABLE_MASK;

	writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
	return 0;
	}

	static const struct rtc_class_ops vt8500_rtc_ops = {
	.read_time = vt8500_rtc_read_time,
	.set_time = vt8500_rtc_set_time,
	.read_alarm = vt8500_rtc_read_alarm,
	.set_alarm = vt8500_rtc_set_alarm,
	.alarm_irq_enable = vt8500_alarm_irq_enable,
	};

	static int vt8500_rtc_probe(struct platform_device *pdev)
	{
	struct vt8500_rtc *vt8500_rtc;
	int ret;

	vt8500_rtc = devm_kzalloc(&pdev->dev,
	sizeof(struct vt8500_rtc), GFP_KERNEL);
	if (!vt8500_rtc)
	return -ENOMEM;

	spin_lock_init(&vt8500_rtc->lock);
	platform_set_drvdata(pdev, vt8500_rtc);

	vt8500_rtc->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!vt8500_rtc->res) {
	dev_err(&pdev->dev, "No I/O memory resource defined\n");
	return -ENXIO;
	}

	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
	if (vt8500_rtc->irq_alarm < 0) {
	dev_err(&pdev->dev, "No alarm IRQ resource defined\n");
	return -ENXIO;
	}

	vt8500_rtc->res = request_mem_region(vt8500_rtc->res->start,
	resource_size(vt8500_rtc->res),
	"vt8500-rtc");
	if (vt8500_rtc->res == NULL) {
	dev_err(&pdev->dev, "failed to request I/O memory\n");
	return -EBUSY;
	}

	vt8500_rtc->regbase = ioremap(vt8500_rtc->res->start,
	resource_size(vt8500_rtc->res));
	if (!vt8500_rtc->regbase) {
	dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
	ret = -EBUSY;
	goto err_release;
	}

	/* Enable RTC and set it to 24-hour mode */
	writel(VT8500_RTC_CR_ENABLE \| VT8500_RTC_CR_24H,
	vt8500_rtc->regbase + VT8500_RTC_CR);

	vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
	&vt8500_rtc_ops, THIS_MODULE);
	if (IS_ERR(vt8500_rtc->rtc)) {
	ret = PTR_ERR(vt8500_rtc->rtc);
	dev_err(&pdev->dev,
	"Failed to register RTC device -> %d\n", ret);
	goto err_unmap;
	}

	ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, 0,
	"rtc alarm", vt8500_rtc);
	if (ret < 0) {
	dev_err(&pdev->dev, "can't get irq %i, err %d\n",
	vt8500_rtc->irq_alarm, ret);
	goto err_unreg;
	}

	return 0;

	err_unreg:
	rtc_device_unregister(vt8500_rtc->rtc);
	err_unmap:
	iounmap(vt8500_rtc->regbase);
	err_release:
	release_mem_region(vt8500_rtc->res->start,
	resource_size(vt8500_rtc->res));
	return ret;
	}

	static int vt8500_rtc_remove(struct platform_device *pdev)
	{
	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);

	free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);

	rtc_device_unregister(vt8500_rtc->rtc);

	/* Disable alarm matching */
	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
	iounmap(vt8500_rtc->regbase);
	release_mem_region(vt8500_rtc->res->start,
	resource_size(vt8500_rtc->res));

	platform_set_drvdata(pdev, NULL);

	return 0;
	}

	static const struct of_device_id wmt_dt_ids[] = {
	{ .compatible = "via,vt8500-rtc", },
	{}
	};

	static struct platform_driver vt8500_rtc_driver = {
	.probe = vt8500_rtc_probe,
	.remove = vt8500_rtc_remove,
	.driver = {
	.name = "vt8500-rtc",
	.owner = THIS_MODULE,
	.of_match_table = of_match_ptr(wmt_dt_ids),
	},
	};

	module_platform_driver(vt8500_rtc_driver);

	MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
	MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:vt8500-rtc");