drivers/rtc/rtc-lpc24xx.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * RTC driver for NXP LPC178x/18xx/43xx Real-Time Clock (RTC)
  *
  * Copyright (C) 2011 NXP Semiconductors
  * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
  */

 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>

 /* LPC24xx RTC register offsets and bits */
 #define LPC24XX_ILR		0x00
 #define  LPC24XX_RTCCIF		BIT(0)
 #define  LPC24XX_RTCALF		BIT(1)
 #define LPC24XX_CTC		0x04
 #define LPC24XX_CCR		0x08
 #define  LPC24XX_CLKEN		BIT(0)
 #define  LPC178X_CCALEN		BIT(4)
 #define LPC24XX_CIIR		0x0c
 #define LPC24XX_AMR		0x10
 #define  LPC24XX_ALARM_DISABLE	0xff
 #define LPC24XX_CTIME0		0x14
 #define LPC24XX_CTIME1		0x18
 #define LPC24XX_CTIME2		0x1c
 #define LPC24XX_SEC		0x20
 #define LPC24XX_MIN		0x24
 #define LPC24XX_HOUR		0x28
 #define LPC24XX_DOM		0x2c
 #define LPC24XX_DOW		0x30
 #define LPC24XX_DOY		0x34
 #define LPC24XX_MONTH		0x38
 #define LPC24XX_YEAR		0x3c
 #define LPC24XX_ALSEC		0x60
 #define LPC24XX_ALMIN		0x64
 #define LPC24XX_ALHOUR		0x68
 #define LPC24XX_ALDOM		0x6c
 #define LPC24XX_ALDOW		0x70
 #define LPC24XX_ALDOY		0x74
 #define LPC24XX_ALMON		0x78
 #define LPC24XX_ALYEAR		0x7c

 /* Macros to read fields in consolidated time (CT) registers */
 #define CT0_SECS(x)		(((x) >> 0)  & 0x3f)
 #define CT0_MINS(x)		(((x) >> 8)  & 0x3f)
 #define CT0_HOURS(x)		(((x) >> 16) & 0x1f)
 #define CT0_DOW(x)		(((x) >> 24) & 0x07)
 #define CT1_DOM(x)		(((x) >> 0)  & 0x1f)
 #define CT1_MONTH(x)		(((x) >> 8)  & 0x0f)
 #define CT1_YEAR(x)		(((x) >> 16) & 0xfff)
 #define CT2_DOY(x)		(((x) >> 0)  & 0xfff)

 #define rtc_readl(dev, reg)		readl((dev)->rtc_base + (reg))
 #define rtc_writel(dev, reg, val)	writel((val), (dev)->rtc_base + (reg))

 struct lpc24xx_rtc {
 	void __iomem *rtc_base;
 	struct rtc_device *rtc;
 	struct clk *clk_rtc;
 	struct clk *clk_reg;
 };

 static int lpc24xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

 	/* Disable RTC during update */
 	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

 	rtc_writel(rtc, LPC24XX_SEC,	tm->tm_sec);
 	rtc_writel(rtc, LPC24XX_MIN,	tm->tm_min);
 	rtc_writel(rtc, LPC24XX_HOUR,	tm->tm_hour);
 	rtc_writel(rtc, LPC24XX_DOW,	tm->tm_wday);
 	rtc_writel(rtc, LPC24XX_DOM,	tm->tm_mday);
 	rtc_writel(rtc, LPC24XX_DOY,	tm->tm_yday);
 	rtc_writel(rtc, LPC24XX_MONTH,	tm->tm_mon);
 	rtc_writel(rtc, LPC24XX_YEAR,	tm->tm_year);

 	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);

 	return 0;
 }

 static int lpc24xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
 	u32 ct0, ct1, ct2;

 	ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
 	ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
 	ct2 = rtc_readl(rtc, LPC24XX_CTIME2);

 	tm->tm_sec  = CT0_SECS(ct0);
 	tm->tm_min  = CT0_MINS(ct0);
 	tm->tm_hour = CT0_HOURS(ct0);
 	tm->tm_wday = CT0_DOW(ct0);
 	tm->tm_mon  = CT1_MONTH(ct1);
 	tm->tm_mday = CT1_DOM(ct1);
 	tm->tm_year = CT1_YEAR(ct1);
 	tm->tm_yday = CT2_DOY(ct2);

 	return 0;
 }

 static int lpc24xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 {
 	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &wkalrm->time;

 	tm->tm_sec  = rtc_readl(rtc, LPC24XX_ALSEC);
 	tm->tm_min  = rtc_readl(rtc, LPC24XX_ALMIN);
 	tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
 	tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
 	tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
 	tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
 	tm->tm_mon  = rtc_readl(rtc, LPC24XX_ALMON);
 	tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);

 	wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
 	wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);

 	return rtc_valid_tm(&wkalrm->time);
 }

 static int lpc24xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 {
 	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
 	struct rtc_time *tm = &wkalrm->time;

 	/* Disable alarm irq during update */
 	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

 	rtc_writel(rtc, LPC24XX_ALSEC,  tm->tm_sec);
 	rtc_writel(rtc, LPC24XX_ALMIN,  tm->tm_min);
 	rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
 	rtc_writel(rtc, LPC24XX_ALDOM,  tm->tm_mday);
 	rtc_writel(rtc, LPC24XX_ALDOW,  tm->tm_wday);
 	rtc_writel(rtc, LPC24XX_ALDOY,  tm->tm_yday);
 	rtc_writel(rtc, LPC24XX_ALMON,  tm->tm_mon);
 	rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);

 	if (wkalrm->enabled)
 		rtc_writel(rtc, LPC24XX_AMR, 0);

 	return 0;
 }

 static int lpc24xx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 {
 	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

 	if (enable)
 		rtc_writel(rtc, LPC24XX_AMR, 0);
 	else
 		rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

 	return 0;
 }

 static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *data)
 {
 	unsigned long events = RTC_IRQF;
 	struct lpc24xx_rtc *rtc = data;
 	u32 rtc_iir;

 	/* Check interrupt cause */
 	rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
 	if (rtc_iir & LPC24XX_RTCALF) {
 		events |= RTC_AF;
 		rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
 	}

 	/* Clear interrupt status and report event */
 	rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
 	rtc_update_irq(rtc->rtc, 1, events);

 	return IRQ_HANDLED;
 }

 static const struct rtc_class_ops lpc24xx_rtc_ops = {
 	.read_time		= lpc24xx_rtc_read_time,
 	.set_time		= lpc24xx_rtc_set_time,
 	.read_alarm		= lpc24xx_rtc_read_alarm,
 	.set_alarm		= lpc24xx_rtc_set_alarm,
 	.alarm_irq_enable	= lpc24xx_rtc_alarm_irq_enable,
 };

 static int lpc24xx_rtc_probe(struct platform_device *pdev)
 {
 	struct lpc24xx_rtc *rtc;
 	int irq, ret;

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

 	rtc->rtc_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(rtc->rtc_base))
 		return PTR_ERR(rtc->rtc_base);

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_warn(&pdev->dev, "can't get interrupt resource\n");
 		return irq;
 	}

 	rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
 	if (IS_ERR(rtc->clk_rtc)) {
 		dev_err(&pdev->dev, "error getting rtc clock\n");
 		return PTR_ERR(rtc->clk_rtc);
 	}

 	rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
 	if (IS_ERR(rtc->clk_reg)) {
 		dev_err(&pdev->dev, "error getting reg clock\n");
 		return PTR_ERR(rtc->clk_reg);
 	}

 	ret = clk_prepare_enable(rtc->clk_rtc);
 	if (ret) {
 		dev_err(&pdev->dev, "unable to enable rtc clock\n");
 		return ret;
 	}

 	ret = clk_prepare_enable(rtc->clk_reg);
 	if (ret) {
 		dev_err(&pdev->dev, "unable to enable reg clock\n");
 		goto disable_rtc_clk;
 	}

 	platform_set_drvdata(pdev, rtc);

 	/* Clear any pending interrupts */
 	rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF | LPC24XX_RTCALF);

 	/* Enable RTC count */
 	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);

 	ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
 			       pdev->name, rtc);
 	if (ret < 0) {
 		dev_warn(&pdev->dev, "can't request interrupt\n");
 		goto disable_clks;
 	}

 	rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc24xx-rtc",
 					    &lpc24xx_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc->rtc)) {
 		dev_err(&pdev->dev, "can't register rtc device\n");
 		ret = PTR_ERR(rtc->rtc);
 		goto disable_clks;
 	}

 	return 0;

 disable_clks:
 	clk_disable_unprepare(rtc->clk_reg);
 disable_rtc_clk:
 	clk_disable_unprepare(rtc->clk_rtc);
 	return ret;
 }

 static int lpc24xx_rtc_remove(struct platform_device *pdev)
 {
 	struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);

 	/* Ensure all interrupt sources are masked */
 	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
 	rtc_writel(rtc, LPC24XX_CIIR, 0);

 	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

 	clk_disable_unprepare(rtc->clk_rtc);
 	clk_disable_unprepare(rtc->clk_reg);

 	return 0;
 }

 static const struct of_device_id lpc24xx_rtc_match[] = {
 	{ .compatible = "nxp,lpc1788-rtc" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);

 static struct platform_driver lpc24xx_rtc_driver = {
 	.probe	= lpc24xx_rtc_probe,
 	.remove	= lpc24xx_rtc_remove,
 	.driver	= {
 		.name = "lpc24xx-rtc",
 		.of_match_table	= lpc24xx_rtc_match,
 	},
 };
 module_platform_driver(lpc24xx_rtc_driver);

 MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com>");
 MODULE_DESCRIPTION("RTC driver for the LPC178x/18xx/408x/43xx SoCs");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* RTC driver for NXP LPC178x/18xx/43xx Real-Time Clock (RTC)
	*
	* Copyright (C) 2011 NXP Semiconductors
	* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
	*/

	#include <linux/clk.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/rtc.h>

	/* LPC24xx RTC register offsets and bits */
	#define LPC24XX_ILR 0x00
	#define LPC24XX_RTCCIF BIT(0)
	#define LPC24XX_RTCALF BIT(1)
	#define LPC24XX_CTC 0x04
	#define LPC24XX_CCR 0x08
	#define LPC24XX_CLKEN BIT(0)
	#define LPC178X_CCALEN BIT(4)
	#define LPC24XX_CIIR 0x0c
	#define LPC24XX_AMR 0x10
	#define LPC24XX_ALARM_DISABLE 0xff
	#define LPC24XX_CTIME0 0x14
	#define LPC24XX_CTIME1 0x18
	#define LPC24XX_CTIME2 0x1c
	#define LPC24XX_SEC 0x20
	#define LPC24XX_MIN 0x24
	#define LPC24XX_HOUR 0x28
	#define LPC24XX_DOM 0x2c
	#define LPC24XX_DOW 0x30
	#define LPC24XX_DOY 0x34
	#define LPC24XX_MONTH 0x38
	#define LPC24XX_YEAR 0x3c
	#define LPC24XX_ALSEC 0x60
	#define LPC24XX_ALMIN 0x64
	#define LPC24XX_ALHOUR 0x68
	#define LPC24XX_ALDOM 0x6c
	#define LPC24XX_ALDOW 0x70
	#define LPC24XX_ALDOY 0x74
	#define LPC24XX_ALMON 0x78
	#define LPC24XX_ALYEAR 0x7c

	/* Macros to read fields in consolidated time (CT) registers */
	#define CT0_SECS(x) (((x) >> 0) & 0x3f)
	#define CT0_MINS(x) (((x) >> 8) & 0x3f)
	#define CT0_HOURS(x) (((x) >> 16) & 0x1f)
	#define CT0_DOW(x) (((x) >> 24) & 0x07)
	#define CT1_DOM(x) (((x) >> 0) & 0x1f)
	#define CT1_MONTH(x) (((x) >> 8) & 0x0f)
	#define CT1_YEAR(x) (((x) >> 16) & 0xfff)
	#define CT2_DOY(x) (((x) >> 0) & 0xfff)

	#define rtc_readl(dev, reg) readl((dev)->rtc_base + (reg))
	#define rtc_writel(dev, reg, val) writel((val), (dev)->rtc_base + (reg))

	struct lpc24xx_rtc {
	void __iomem *rtc_base;
	struct rtc_device *rtc;
	struct clk *clk_rtc;
	struct clk *clk_reg;
	};

	static int lpc24xx_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

	/* Disable RTC during update */
	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

	rtc_writel(rtc, LPC24XX_SEC, tm->tm_sec);
	rtc_writel(rtc, LPC24XX_MIN, tm->tm_min);
	rtc_writel(rtc, LPC24XX_HOUR, tm->tm_hour);
	rtc_writel(rtc, LPC24XX_DOW, tm->tm_wday);
	rtc_writel(rtc, LPC24XX_DOM, tm->tm_mday);
	rtc_writel(rtc, LPC24XX_DOY, tm->tm_yday);
	rtc_writel(rtc, LPC24XX_MONTH, tm->tm_mon);
	rtc_writel(rtc, LPC24XX_YEAR, tm->tm_year);

	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN \| LPC178X_CCALEN);

	return 0;
	}

	static int lpc24xx_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
	u32 ct0, ct1, ct2;

	ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
	ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
	ct2 = rtc_readl(rtc, LPC24XX_CTIME2);

	tm->tm_sec = CT0_SECS(ct0);
	tm->tm_min = CT0_MINS(ct0);
	tm->tm_hour = CT0_HOURS(ct0);
	tm->tm_wday = CT0_DOW(ct0);
	tm->tm_mon = CT1_MONTH(ct1);
	tm->tm_mday = CT1_DOM(ct1);
	tm->tm_year = CT1_YEAR(ct1);
	tm->tm_yday = CT2_DOY(ct2);

	return 0;
	}

	static int lpc24xx_rtc_read_alarm(struct device dev, struct rtc_wkalrm wkalrm)
	{
	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &wkalrm->time;

	tm->tm_sec = rtc_readl(rtc, LPC24XX_ALSEC);
	tm->tm_min = rtc_readl(rtc, LPC24XX_ALMIN);
	tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
	tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
	tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
	tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
	tm->tm_mon = rtc_readl(rtc, LPC24XX_ALMON);
	tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);

	wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
	wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);

	return rtc_valid_tm(&wkalrm->time);
	}

	static int lpc24xx_rtc_set_alarm(struct device dev, struct rtc_wkalrm wkalrm)
	{
	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
	struct rtc_time *tm = &wkalrm->time;

	/* Disable alarm irq during update */
	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

	rtc_writel(rtc, LPC24XX_ALSEC, tm->tm_sec);
	rtc_writel(rtc, LPC24XX_ALMIN, tm->tm_min);
	rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
	rtc_writel(rtc, LPC24XX_ALDOM, tm->tm_mday);
	rtc_writel(rtc, LPC24XX_ALDOW, tm->tm_wday);
	rtc_writel(rtc, LPC24XX_ALDOY, tm->tm_yday);
	rtc_writel(rtc, LPC24XX_ALMON, tm->tm_mon);
	rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);

	if (wkalrm->enabled)
	rtc_writel(rtc, LPC24XX_AMR, 0);

	return 0;
	}

	static int lpc24xx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
	{
	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

	if (enable)
	rtc_writel(rtc, LPC24XX_AMR, 0);
	else
	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

	return 0;
	}

	static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *data)
	{
	unsigned long events = RTC_IRQF;
	struct lpc24xx_rtc *rtc = data;
	u32 rtc_iir;

	/* Check interrupt cause */
	rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
	if (rtc_iir & LPC24XX_RTCALF) {
	events \|= RTC_AF;
	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
	}

	/* Clear interrupt status and report event */
	rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
	rtc_update_irq(rtc->rtc, 1, events);

	return IRQ_HANDLED;
	}

	static const struct rtc_class_ops lpc24xx_rtc_ops = {
	.read_time = lpc24xx_rtc_read_time,
	.set_time = lpc24xx_rtc_set_time,
	.read_alarm = lpc24xx_rtc_read_alarm,
	.set_alarm = lpc24xx_rtc_set_alarm,
	.alarm_irq_enable = lpc24xx_rtc_alarm_irq_enable,
	};

	static int lpc24xx_rtc_probe(struct platform_device *pdev)
	{
	struct lpc24xx_rtc *rtc;
	int irq, ret;

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

	rtc->rtc_base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(rtc->rtc_base))
	return PTR_ERR(rtc->rtc_base);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_warn(&pdev->dev, "can't get interrupt resource\n");
	return irq;
	}

	rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
	if (IS_ERR(rtc->clk_rtc)) {
	dev_err(&pdev->dev, "error getting rtc clock\n");
	return PTR_ERR(rtc->clk_rtc);
	}

	rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
	if (IS_ERR(rtc->clk_reg)) {
	dev_err(&pdev->dev, "error getting reg clock\n");
	return PTR_ERR(rtc->clk_reg);
	}

	ret = clk_prepare_enable(rtc->clk_rtc);
	if (ret) {
	dev_err(&pdev->dev, "unable to enable rtc clock\n");
	return ret;
	}

	ret = clk_prepare_enable(rtc->clk_reg);
	if (ret) {
	dev_err(&pdev->dev, "unable to enable reg clock\n");
	goto disable_rtc_clk;
	}

	platform_set_drvdata(pdev, rtc);

	/* Clear any pending interrupts */
	rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF \| LPC24XX_RTCALF);

	/* Enable RTC count */
	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN \| LPC178X_CCALEN);

	ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
	pdev->name, rtc);
	if (ret < 0) {
	dev_warn(&pdev->dev, "can't request interrupt\n");
	goto disable_clks;
	}

	rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc24xx-rtc",
	&lpc24xx_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc->rtc)) {
	dev_err(&pdev->dev, "can't register rtc device\n");
	ret = PTR_ERR(rtc->rtc);
	goto disable_clks;
	}

	return 0;

	disable_clks:
	clk_disable_unprepare(rtc->clk_reg);
	disable_rtc_clk:
	clk_disable_unprepare(rtc->clk_rtc);
	return ret;
	}

	static int lpc24xx_rtc_remove(struct platform_device *pdev)
	{
	struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);

	/* Ensure all interrupt sources are masked */
	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
	rtc_writel(rtc, LPC24XX_CIIR, 0);

	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

	clk_disable_unprepare(rtc->clk_rtc);
	clk_disable_unprepare(rtc->clk_reg);

	return 0;
	}

	static const struct of_device_id lpc24xx_rtc_match[] = {
	{ .compatible = "nxp,lpc1788-rtc" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);

	static struct platform_driver lpc24xx_rtc_driver = {
	.probe = lpc24xx_rtc_probe,
	.remove = lpc24xx_rtc_remove,
	.driver = {
	.name = "lpc24xx-rtc",
	.of_match_table = lpc24xx_rtc_match,
	},
	};
	module_platform_driver(lpc24xx_rtc_driver);

	MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com>");
	MODULE_DESCRIPTION("RTC driver for the LPC178x/18xx/408x/43xx SoCs");
	MODULE_LICENSE("GPL");