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

 // SPDX-License-Identifier: GPL-2.0+
 //
 // Copyright 2004-2008 Freescale Semiconductor, Inc. All Rights Reserved.

 #include <linux/io.h>
 #include <linux/rtc.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/pm_wakeirq.h>
 #include <linux/clk.h>
 #include <linux/of.h>
 #include <linux/of_device.h>

 #define RTC_INPUT_CLK_32768HZ	(0x00 << 5)
 #define RTC_INPUT_CLK_32000HZ	(0x01 << 5)
 #define RTC_INPUT_CLK_38400HZ	(0x02 << 5)

 #define RTC_SW_BIT      (1 << 0)
 #define RTC_ALM_BIT     (1 << 2)
 #define RTC_1HZ_BIT     (1 << 4)
 #define RTC_2HZ_BIT     (1 << 7)
 #define RTC_SAM0_BIT    (1 << 8)
 #define RTC_SAM1_BIT    (1 << 9)
 #define RTC_SAM2_BIT    (1 << 10)
 #define RTC_SAM3_BIT    (1 << 11)
 #define RTC_SAM4_BIT    (1 << 12)
 #define RTC_SAM5_BIT    (1 << 13)
 #define RTC_SAM6_BIT    (1 << 14)
 #define RTC_SAM7_BIT    (1 << 15)
 #define PIT_ALL_ON      (RTC_2HZ_BIT | RTC_SAM0_BIT | RTC_SAM1_BIT | \
 			 RTC_SAM2_BIT | RTC_SAM3_BIT | RTC_SAM4_BIT | \
 			 RTC_SAM5_BIT | RTC_SAM6_BIT | RTC_SAM7_BIT)

 #define RTC_ENABLE_BIT  (1 << 7)

 #define MAX_PIE_NUM     9
 #define MAX_PIE_FREQ    512

 #define MXC_RTC_TIME	0
 #define MXC_RTC_ALARM	1

 #define RTC_HOURMIN	0x00	/*  32bit rtc hour/min counter reg */
 #define RTC_SECOND	0x04	/*  32bit rtc seconds counter reg */
 #define RTC_ALRM_HM	0x08	/*  32bit rtc alarm hour/min reg */
 #define RTC_ALRM_SEC	0x0C	/*  32bit rtc alarm seconds reg */
 #define RTC_RTCCTL	0x10	/*  32bit rtc control reg */
 #define RTC_RTCISR	0x14	/*  32bit rtc interrupt status reg */
 #define RTC_RTCIENR	0x18	/*  32bit rtc interrupt enable reg */
 #define RTC_STPWCH	0x1C	/*  32bit rtc stopwatch min reg */
 #define RTC_DAYR	0x20	/*  32bit rtc days counter reg */
 #define RTC_DAYALARM	0x24	/*  32bit rtc day alarm reg */
 #define RTC_TEST1	0x28	/*  32bit rtc test reg 1 */
 #define RTC_TEST2	0x2C	/*  32bit rtc test reg 2 */
 #define RTC_TEST3	0x30	/*  32bit rtc test reg 3 */

 enum imx_rtc_type {
 	IMX1_RTC,
 	IMX21_RTC,
 };

 struct rtc_plat_data {
 	struct rtc_device *rtc;
 	void __iomem *ioaddr;
 	int irq;
 	struct clk *clk_ref;
 	struct clk *clk_ipg;
 	struct rtc_time g_rtc_alarm;
 	enum imx_rtc_type devtype;
 };

 static const struct platform_device_id imx_rtc_devtype[] = {
 	{
 		.name = "imx1-rtc",
 		.driver_data = IMX1_RTC,
 	}, {
 		.name = "imx21-rtc",
 		.driver_data = IMX21_RTC,
 	}, {
 		/* sentinel */
 	}
 };
 MODULE_DEVICE_TABLE(platform, imx_rtc_devtype);

 #ifdef CONFIG_OF
 static const struct of_device_id imx_rtc_dt_ids[] = {
 	{ .compatible = "fsl,imx1-rtc", .data = (const void *)IMX1_RTC },
 	{ .compatible = "fsl,imx21-rtc", .data = (const void *)IMX21_RTC },
 	{}
 };
 MODULE_DEVICE_TABLE(of, imx_rtc_dt_ids);
 #endif

 static inline int is_imx1_rtc(struct rtc_plat_data *data)
 {
 	return data->devtype == IMX1_RTC;
 }

 /*
  * This function is used to obtain the RTC time or the alarm value in
  * second.
  */
 static time64_t get_alarm_or_time(struct device *dev, int time_alarm)
 {
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	u32 day = 0, hr = 0, min = 0, sec = 0, hr_min = 0;

 	switch (time_alarm) {
 	case MXC_RTC_TIME:
 		day = readw(ioaddr + RTC_DAYR);
 		hr_min = readw(ioaddr + RTC_HOURMIN);
 		sec = readw(ioaddr + RTC_SECOND);
 		break;
 	case MXC_RTC_ALARM:
 		day = readw(ioaddr + RTC_DAYALARM);
 		hr_min = readw(ioaddr + RTC_ALRM_HM) & 0xffff;
 		sec = readw(ioaddr + RTC_ALRM_SEC);
 		break;
 	}

 	hr = hr_min >> 8;
 	min = hr_min & 0xff;

 	return ((((time64_t)day * 24 + hr) * 60) + min) * 60 + sec;
 }

 /*
  * This function sets the RTC alarm value or the time value.
  */
 static void set_alarm_or_time(struct device *dev, int time_alarm, time64_t time)
 {
 	u32 tod, day, hr, min, sec, temp;
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 	void __iomem *ioaddr = pdata->ioaddr;

 	day = div_s64_rem(time, 86400, &tod);

 	/* time is within a day now */
 	hr = tod / 3600;
 	tod -= hr * 3600;

 	/* time is within an hour now */
 	min = tod / 60;
 	sec = tod - min * 60;

 	temp = (hr << 8) + min;

 	switch (time_alarm) {
 	case MXC_RTC_TIME:
 		writew(day, ioaddr + RTC_DAYR);
 		writew(sec, ioaddr + RTC_SECOND);
 		writew(temp, ioaddr + RTC_HOURMIN);
 		break;
 	case MXC_RTC_ALARM:
 		writew(day, ioaddr + RTC_DAYALARM);
 		writew(sec, ioaddr + RTC_ALRM_SEC);
 		writew(temp, ioaddr + RTC_ALRM_HM);
 		break;
 	}
 }

 /*
  * This function updates the RTC alarm registers and then clears all the
  * interrupt status bits.
  */
 static void rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
 {
 	time64_t time;
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 	void __iomem *ioaddr = pdata->ioaddr;

 	time = rtc_tm_to_time64(alrm);

 	/* clear all the interrupt status bits */
 	writew(readw(ioaddr + RTC_RTCISR), ioaddr + RTC_RTCISR);
 	set_alarm_or_time(dev, MXC_RTC_ALARM, time);
 }

 static void mxc_rtc_irq_enable(struct device *dev, unsigned int bit,
 				unsigned int enabled)
 {
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 	void __iomem *ioaddr = pdata->ioaddr;
 	u32 reg;
 	unsigned long flags;

 	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
 	reg = readw(ioaddr + RTC_RTCIENR);

 	if (enabled)
 		reg |= bit;
 	else
 		reg &= ~bit;

 	writew(reg, ioaddr + RTC_RTCIENR);
 	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
 }

 /* This function is the RTC interrupt service routine. */
 static irqreturn_t mxc_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 flags;
 	u32 status;
 	u32 events = 0;

 	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
 	status = readw(ioaddr + RTC_RTCISR) & readw(ioaddr + RTC_RTCIENR);
 	/* clear interrupt sources */
 	writew(status, ioaddr + RTC_RTCISR);

 	/* update irq data & counter */
 	if (status & RTC_ALM_BIT) {
 		events |= (RTC_AF | RTC_IRQF);
 		/* RTC alarm should be one-shot */
 		mxc_rtc_irq_enable(&pdev->dev, RTC_ALM_BIT, 0);
 	}

 	if (status & PIT_ALL_ON)
 		events |= (RTC_PF | RTC_IRQF);

 	rtc_update_irq(pdata->rtc, 1, events);
 	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);

 	return IRQ_HANDLED;
 }

 static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	mxc_rtc_irq_enable(dev, RTC_ALM_BIT, enabled);
 	return 0;
 }

 /*
  * This function reads the current RTC time into tm in Gregorian date.
  */
 static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	time64_t val;

 	/* Avoid roll-over from reading the different registers */
 	do {
 		val = get_alarm_or_time(dev, MXC_RTC_TIME);
 	} while (val != get_alarm_or_time(dev, MXC_RTC_TIME));

 	rtc_time64_to_tm(val, tm);

 	return 0;
 }

 /*
  * This function sets the internal RTC time based on tm in Gregorian date.
  */
 static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	time64_t time = rtc_tm_to_time64(tm);

 	/* Avoid roll-over from reading the different registers */
 	do {
 		set_alarm_or_time(dev, MXC_RTC_TIME, time);
 	} while (time != get_alarm_or_time(dev, MXC_RTC_TIME));

 	return 0;
 }

 /*
  * This function reads the current alarm value into the passed in 'alrm'
  * argument. It updates the alrm's pending field value based on the whether
  * an alarm interrupt occurs or not.
  */
 static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 	void __iomem *ioaddr = pdata->ioaddr;

 	rtc_time64_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
 	alrm->pending = ((readw(ioaddr + RTC_RTCISR) & RTC_ALM_BIT)) ? 1 : 0;

 	return 0;
 }

 /*
  * This function sets the RTC alarm based on passed in alrm.
  */
 static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);

 	rtc_update_alarm(dev, &alrm->time);

 	memcpy(&pdata->g_rtc_alarm, &alrm->time, sizeof(struct rtc_time));
 	mxc_rtc_irq_enable(dev, RTC_ALM_BIT, alrm->enabled);

 	return 0;
 }

 /* RTC layer */
 static const struct rtc_class_ops mxc_rtc_ops = {
 	.read_time		= mxc_rtc_read_time,
 	.set_time		= mxc_rtc_set_time,
 	.read_alarm		= mxc_rtc_read_alarm,
 	.set_alarm		= mxc_rtc_set_alarm,
 	.alarm_irq_enable	= mxc_rtc_alarm_irq_enable,
 };

 static int mxc_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 	struct rtc_plat_data *pdata = NULL;
 	u32 reg;
 	unsigned long rate;
 	int ret;
 	const struct of_device_id *of_id;

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

 	of_id = of_match_device(imx_rtc_dt_ids, &pdev->dev);
 	if (of_id)
 		pdata->devtype = (enum imx_rtc_type)of_id->data;
 	else
 		pdata->devtype = pdev->id_entry->driver_data;

 	pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(pdata->ioaddr))
 		return PTR_ERR(pdata->ioaddr);

 	rtc = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	pdata->rtc = rtc;
 	rtc->ops = &mxc_rtc_ops;
 	if (is_imx1_rtc(pdata)) {
 		struct rtc_time tm;

 		/* 9bit days + hours minutes seconds */
 		rtc->range_max = (1 << 9) * 86400 - 1;

 		/*
 		 * Set the start date as beginning of the current year. This can
 		 * be overridden using device tree.
 		 */
 		rtc_time64_to_tm(ktime_get_real_seconds(), &tm);
 		rtc->start_secs =  mktime64(tm.tm_year, 1, 1, 0, 0, 0);
 		rtc->set_start_time = true;
 	} else {
 		/* 16bit days + hours minutes seconds */
 		rtc->range_max = (1 << 16) * 86400ULL - 1;
 	}

 	pdata->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(pdata->clk_ipg)) {
 		dev_err(&pdev->dev, "unable to get ipg clock!\n");
 		return PTR_ERR(pdata->clk_ipg);
 	}

 	ret = clk_prepare_enable(pdata->clk_ipg);
 	if (ret)
 		return ret;

 	pdata->clk_ref = devm_clk_get(&pdev->dev, "ref");
 	if (IS_ERR(pdata->clk_ref)) {
 		dev_err(&pdev->dev, "unable to get ref clock!\n");
 		ret = PTR_ERR(pdata->clk_ref);
 		goto exit_put_clk_ipg;
 	}

 	ret = clk_prepare_enable(pdata->clk_ref);
 	if (ret)
 		goto exit_put_clk_ipg;

 	rate = clk_get_rate(pdata->clk_ref);

 	if (rate == 32768)
 		reg = RTC_INPUT_CLK_32768HZ;
 	else if (rate == 32000)
 		reg = RTC_INPUT_CLK_32000HZ;
 	else if (rate == 38400)
 		reg = RTC_INPUT_CLK_38400HZ;
 	else {
 		dev_err(&pdev->dev, "rtc clock is not valid (%lu)\n", rate);
 		ret = -EINVAL;
 		goto exit_put_clk_ref;
 	}

 	reg |= RTC_ENABLE_BIT;
 	writew(reg, (pdata->ioaddr + RTC_RTCCTL));
 	if (((readw(pdata->ioaddr + RTC_RTCCTL)) & RTC_ENABLE_BIT) == 0) {
 		dev_err(&pdev->dev, "hardware module can't be enabled!\n");
 		ret = -EIO;
 		goto exit_put_clk_ref;
 	}

 	platform_set_drvdata(pdev, pdata);

 	/* Configure and enable the RTC */
 	pdata->irq = platform_get_irq(pdev, 0);

 	if (pdata->irq >= 0 &&
 	    devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt,
 			     IRQF_SHARED, pdev->name, pdev) < 0) {
 		dev_warn(&pdev->dev, "interrupt not available.\n");
 		pdata->irq = -1;
 	}

 	if (pdata->irq >= 0) {
 		device_init_wakeup(&pdev->dev, 1);
 		ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq);
 		if (ret)
 			dev_err(&pdev->dev, "failed to enable irq wake\n");
 	}

 	ret = rtc_register_device(rtc);
 	if (ret)
 		goto exit_put_clk_ref;

 	return 0;

 exit_put_clk_ref:
 	clk_disable_unprepare(pdata->clk_ref);
 exit_put_clk_ipg:
 	clk_disable_unprepare(pdata->clk_ipg);

 	return ret;
 }

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

 	clk_disable_unprepare(pdata->clk_ref);
 	clk_disable_unprepare(pdata->clk_ipg);

 	return 0;
 }

 static struct platform_driver mxc_rtc_driver = {
 	.driver = {
 		   .name	= "mxc_rtc",
 		   .of_match_table = of_match_ptr(imx_rtc_dt_ids),
 	},
 	.id_table = imx_rtc_devtype,
 	.probe = mxc_rtc_probe,
 	.remove = mxc_rtc_remove,
 };

 module_platform_driver(mxc_rtc_driver)

 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 MODULE_DESCRIPTION("RTC driver for Freescale MXC");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	//
	// Copyright 2004-2008 Freescale Semiconductor, Inc. All Rights Reserved.

	#include <linux/io.h>
	#include <linux/rtc.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/pm_wakeirq.h>
	#include <linux/clk.h>
	#include <linux/of.h>
	#include <linux/of_device.h>

	#define RTC_INPUT_CLK_32768HZ (0x00 << 5)
	#define RTC_INPUT_CLK_32000HZ (0x01 << 5)
	#define RTC_INPUT_CLK_38400HZ (0x02 << 5)

	#define RTC_SW_BIT (1 << 0)
	#define RTC_ALM_BIT (1 << 2)
	#define RTC_1HZ_BIT (1 << 4)
	#define RTC_2HZ_BIT (1 << 7)
	#define RTC_SAM0_BIT (1 << 8)
	#define RTC_SAM1_BIT (1 << 9)
	#define RTC_SAM2_BIT (1 << 10)
	#define RTC_SAM3_BIT (1 << 11)
	#define RTC_SAM4_BIT (1 << 12)
	#define RTC_SAM5_BIT (1 << 13)
	#define RTC_SAM6_BIT (1 << 14)
	#define RTC_SAM7_BIT (1 << 15)
	#define PIT_ALL_ON (RTC_2HZ_BIT \| RTC_SAM0_BIT \| RTC_SAM1_BIT \| \
	RTC_SAM2_BIT \| RTC_SAM3_BIT \| RTC_SAM4_BIT \| \
	RTC_SAM5_BIT \| RTC_SAM6_BIT \| RTC_SAM7_BIT)

	#define RTC_ENABLE_BIT (1 << 7)

	#define MAX_PIE_NUM 9
	#define MAX_PIE_FREQ 512

	#define MXC_RTC_TIME 0
	#define MXC_RTC_ALARM 1

	#define RTC_HOURMIN 0x00 /* 32bit rtc hour/min counter reg */
	#define RTC_SECOND 0x04 /* 32bit rtc seconds counter reg */
	#define RTC_ALRM_HM 0x08 /* 32bit rtc alarm hour/min reg */
	#define RTC_ALRM_SEC 0x0C /* 32bit rtc alarm seconds reg */
	#define RTC_RTCCTL 0x10 /* 32bit rtc control reg */
	#define RTC_RTCISR 0x14 /* 32bit rtc interrupt status reg */
	#define RTC_RTCIENR 0x18 /* 32bit rtc interrupt enable reg */
	#define RTC_STPWCH 0x1C /* 32bit rtc stopwatch min reg */
	#define RTC_DAYR 0x20 /* 32bit rtc days counter reg */
	#define RTC_DAYALARM 0x24 /* 32bit rtc day alarm reg */
	#define RTC_TEST1 0x28 /* 32bit rtc test reg 1 */
	#define RTC_TEST2 0x2C /* 32bit rtc test reg 2 */
	#define RTC_TEST3 0x30 /* 32bit rtc test reg 3 */

	enum imx_rtc_type {
	IMX1_RTC,
	IMX21_RTC,
	};

	struct rtc_plat_data {
	struct rtc_device *rtc;
	void __iomem *ioaddr;
	int irq;
	struct clk *clk_ref;
	struct clk *clk_ipg;
	struct rtc_time g_rtc_alarm;
	enum imx_rtc_type devtype;
	};

	static const struct platform_device_id imx_rtc_devtype[] = {
	{
	.name = "imx1-rtc",
	.driver_data = IMX1_RTC,
	}, {
	.name = "imx21-rtc",
	.driver_data = IMX21_RTC,
	}, {
	/* sentinel */
	}
	};
	MODULE_DEVICE_TABLE(platform, imx_rtc_devtype);

	#ifdef CONFIG_OF
	static const struct of_device_id imx_rtc_dt_ids[] = {
	{ .compatible = "fsl,imx1-rtc", .data = (const void *)IMX1_RTC },
	{ .compatible = "fsl,imx21-rtc", .data = (const void *)IMX21_RTC },
	{}
	};
	MODULE_DEVICE_TABLE(of, imx_rtc_dt_ids);
	#endif

	static inline int is_imx1_rtc(struct rtc_plat_data *data)
	{
	return data->devtype == IMX1_RTC;
	}

	/*
	* This function is used to obtain the RTC time or the alarm value in
	* second.
	*/
	static time64_t get_alarm_or_time(struct device *dev, int time_alarm)
	{
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
	void __iomem *ioaddr = pdata->ioaddr;
	u32 day = 0, hr = 0, min = 0, sec = 0, hr_min = 0;

	switch (time_alarm) {
	case MXC_RTC_TIME:
	day = readw(ioaddr + RTC_DAYR);
	hr_min = readw(ioaddr + RTC_HOURMIN);
	sec = readw(ioaddr + RTC_SECOND);
	break;
	case MXC_RTC_ALARM:
	day = readw(ioaddr + RTC_DAYALARM);
	hr_min = readw(ioaddr + RTC_ALRM_HM) & 0xffff;
	sec = readw(ioaddr + RTC_ALRM_SEC);
	break;
	}

	hr = hr_min >> 8;
	min = hr_min & 0xff;

	return ((((time64_t)day * 24 + hr) * 60) + min) * 60 + sec;
	}

	/*
	* This function sets the RTC alarm value or the time value.
	*/
	static void set_alarm_or_time(struct device *dev, int time_alarm, time64_t time)
	{
	u32 tod, day, hr, min, sec, temp;
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
	void __iomem *ioaddr = pdata->ioaddr;

	day = div_s64_rem(time, 86400, &tod);

	/* time is within a day now */
	hr = tod / 3600;
	tod -= hr * 3600;

	/* time is within an hour now */
	min = tod / 60;
	sec = tod - min * 60;

	temp = (hr << 8) + min;

	switch (time_alarm) {
	case MXC_RTC_TIME:
	writew(day, ioaddr + RTC_DAYR);
	writew(sec, ioaddr + RTC_SECOND);
	writew(temp, ioaddr + RTC_HOURMIN);
	break;
	case MXC_RTC_ALARM:
	writew(day, ioaddr + RTC_DAYALARM);
	writew(sec, ioaddr + RTC_ALRM_SEC);
	writew(temp, ioaddr + RTC_ALRM_HM);
	break;
	}
	}

	/*
	* This function updates the RTC alarm registers and then clears all the
	* interrupt status bits.
	*/
	static void rtc_update_alarm(struct device dev, struct rtc_time alrm)
	{
	time64_t time;
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
	void __iomem *ioaddr = pdata->ioaddr;

	time = rtc_tm_to_time64(alrm);

	/* clear all the interrupt status bits */
	writew(readw(ioaddr + RTC_RTCISR), ioaddr + RTC_RTCISR);
	set_alarm_or_time(dev, MXC_RTC_ALARM, time);
	}

	static void mxc_rtc_irq_enable(struct device *dev, unsigned int bit,
	unsigned int enabled)
	{
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
	void __iomem *ioaddr = pdata->ioaddr;
	u32 reg;
	unsigned long flags;

	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
	reg = readw(ioaddr + RTC_RTCIENR);

	if (enabled)
	reg \|= bit;
	else
	reg &= ~bit;

	writew(reg, ioaddr + RTC_RTCIENR);
	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
	}

	/* This function is the RTC interrupt service routine. */
	static irqreturn_t mxc_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 flags;
	u32 status;
	u32 events = 0;

	spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
	status = readw(ioaddr + RTC_RTCISR) & readw(ioaddr + RTC_RTCIENR);
	/* clear interrupt sources */
	writew(status, ioaddr + RTC_RTCISR);

	/* update irq data & counter */
	if (status & RTC_ALM_BIT) {
	events \|= (RTC_AF \| RTC_IRQF);
	/* RTC alarm should be one-shot */
	mxc_rtc_irq_enable(&pdev->dev, RTC_ALM_BIT, 0);
	}

	if (status & PIT_ALL_ON)
	events \|= (RTC_PF \| RTC_IRQF);

	rtc_update_irq(pdata->rtc, 1, events);
	spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);

	return IRQ_HANDLED;
	}

	static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	mxc_rtc_irq_enable(dev, RTC_ALM_BIT, enabled);
	return 0;
	}

	/*
	* This function reads the current RTC time into tm in Gregorian date.
	*/
	static int mxc_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	time64_t val;

	/* Avoid roll-over from reading the different registers */
	do {
	val = get_alarm_or_time(dev, MXC_RTC_TIME);
	} while (val != get_alarm_or_time(dev, MXC_RTC_TIME));

	rtc_time64_to_tm(val, tm);

	return 0;
	}

	/*
	* This function sets the internal RTC time based on tm in Gregorian date.
	*/
	static int mxc_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	time64_t time = rtc_tm_to_time64(tm);

	/* Avoid roll-over from reading the different registers */
	do {
	set_alarm_or_time(dev, MXC_RTC_TIME, time);
	} while (time != get_alarm_or_time(dev, MXC_RTC_TIME));

	return 0;
	}

	/*
	* This function reads the current alarm value into the passed in 'alrm'
	* argument. It updates the alrm's pending field value based on the whether
	* an alarm interrupt occurs or not.
	*/
	static int mxc_rtc_read_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
	void __iomem *ioaddr = pdata->ioaddr;

	rtc_time64_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
	alrm->pending = ((readw(ioaddr + RTC_RTCISR) & RTC_ALM_BIT)) ? 1 : 0;

	return 0;
	}

	/*
	* This function sets the RTC alarm based on passed in alrm.
	*/
	static int mxc_rtc_set_alarm(struct device dev, struct rtc_wkalrm alrm)
	{
	struct rtc_plat_data *pdata = dev_get_drvdata(dev);

	rtc_update_alarm(dev, &alrm->time);

	memcpy(&pdata->g_rtc_alarm, &alrm->time, sizeof(struct rtc_time));
	mxc_rtc_irq_enable(dev, RTC_ALM_BIT, alrm->enabled);

	return 0;
	}

	/* RTC layer */
	static const struct rtc_class_ops mxc_rtc_ops = {
	.read_time = mxc_rtc_read_time,
	.set_time = mxc_rtc_set_time,
	.read_alarm = mxc_rtc_read_alarm,
	.set_alarm = mxc_rtc_set_alarm,
	.alarm_irq_enable = mxc_rtc_alarm_irq_enable,
	};

	static int mxc_rtc_probe(struct platform_device *pdev)
	{
	struct rtc_device *rtc;
	struct rtc_plat_data *pdata = NULL;
	u32 reg;
	unsigned long rate;
	int ret;
	const struct of_device_id *of_id;

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

	of_id = of_match_device(imx_rtc_dt_ids, &pdev->dev);
	if (of_id)
	pdata->devtype = (enum imx_rtc_type)of_id->data;
	else
	pdata->devtype = pdev->id_entry->driver_data;

	pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(pdata->ioaddr))
	return PTR_ERR(pdata->ioaddr);

	rtc = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	pdata->rtc = rtc;
	rtc->ops = &mxc_rtc_ops;
	if (is_imx1_rtc(pdata)) {
	struct rtc_time tm;

	/* 9bit days + hours minutes seconds */
	rtc->range_max = (1 << 9) * 86400 - 1;

	/*
	* Set the start date as beginning of the current year. This can
	* be overridden using device tree.
	*/
	rtc_time64_to_tm(ktime_get_real_seconds(), &tm);
	rtc->start_secs = mktime64(tm.tm_year, 1, 1, 0, 0, 0);
	rtc->set_start_time = true;
	} else {
	/* 16bit days + hours minutes seconds */
	rtc->range_max = (1 << 16) * 86400ULL - 1;
	}

	pdata->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
	if (IS_ERR(pdata->clk_ipg)) {
	dev_err(&pdev->dev, "unable to get ipg clock!\n");
	return PTR_ERR(pdata->clk_ipg);
	}

	ret = clk_prepare_enable(pdata->clk_ipg);
	if (ret)
	return ret;

	pdata->clk_ref = devm_clk_get(&pdev->dev, "ref");
	if (IS_ERR(pdata->clk_ref)) {
	dev_err(&pdev->dev, "unable to get ref clock!\n");
	ret = PTR_ERR(pdata->clk_ref);
	goto exit_put_clk_ipg;
	}

	ret = clk_prepare_enable(pdata->clk_ref);
	if (ret)
	goto exit_put_clk_ipg;

	rate = clk_get_rate(pdata->clk_ref);

	if (rate == 32768)
	reg = RTC_INPUT_CLK_32768HZ;
	else if (rate == 32000)
	reg = RTC_INPUT_CLK_32000HZ;
	else if (rate == 38400)
	reg = RTC_INPUT_CLK_38400HZ;
	else {
	dev_err(&pdev->dev, "rtc clock is not valid (%lu)\n", rate);
	ret = -EINVAL;
	goto exit_put_clk_ref;
	}

	reg \|= RTC_ENABLE_BIT;
	writew(reg, (pdata->ioaddr + RTC_RTCCTL));
	if (((readw(pdata->ioaddr + RTC_RTCCTL)) & RTC_ENABLE_BIT) == 0) {
	dev_err(&pdev->dev, "hardware module can't be enabled!\n");
	ret = -EIO;
	goto exit_put_clk_ref;
	}

	platform_set_drvdata(pdev, pdata);

	/* Configure and enable the RTC */
	pdata->irq = platform_get_irq(pdev, 0);

	if (pdata->irq >= 0 &&
	devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt,
	IRQF_SHARED, pdev->name, pdev) < 0) {
	dev_warn(&pdev->dev, "interrupt not available.\n");
	pdata->irq = -1;
	}

	if (pdata->irq >= 0) {
	device_init_wakeup(&pdev->dev, 1);
	ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq);
	if (ret)
	dev_err(&pdev->dev, "failed to enable irq wake\n");
	}

	ret = rtc_register_device(rtc);
	if (ret)
	goto exit_put_clk_ref;

	return 0;

	exit_put_clk_ref:
	clk_disable_unprepare(pdata->clk_ref);
	exit_put_clk_ipg:
	clk_disable_unprepare(pdata->clk_ipg);

	return ret;
	}

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

	clk_disable_unprepare(pdata->clk_ref);
	clk_disable_unprepare(pdata->clk_ipg);

	return 0;
	}

	static struct platform_driver mxc_rtc_driver = {
	.driver = {
	.name = "mxc_rtc",
	.of_match_table = of_match_ptr(imx_rtc_dt_ids),
	},
	.id_table = imx_rtc_devtype,
	.probe = mxc_rtc_probe,
	.remove = mxc_rtc_remove,
	};

	module_platform_driver(mxc_rtc_driver)

	MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
	MODULE_DESCRIPTION("RTC driver for Freescale MXC");
	MODULE_LICENSE("GPL");