drivers/rtc/rtc_mc146818.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2023 Intel Corporation.
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #define DT_DRV_COMPAT motorola_mc146818

 #include <errno.h>
 #include <zephyr/device.h>
 #include <zephyr/kernel.h>
 #include <zephyr/init.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/spinlock.h>
 #include <zephyr/devicetree.h>
 #include <zephyr/drivers/rtc.h>
 #include <zephyr/sys/sys_io.h>

 #define RTC_STD_INDEX (DT_INST_REG_ADDR_BY_IDX(0, 0))
 #define RTC_STD_TARGET (DT_INST_REG_ADDR_BY_IDX(0, 1))

 /* Time indices in RTC RAM */
 #define RTC_SEC		0x00
 #define RTC_MIN		0x02
 #define RTC_HOUR	0x04

 /* Day of week index in RTC RAM */
 #define RTC_WDAY	0x06

 /* Day of month index in RTC RAM */
 #define RTC_MDAY	0x07

 /* Month and year index in RTC RAM */
 #define RTC_MONTH	0x08
 #define RTC_YEAR	0x09

 /* Y2K Bugfix */
 #define RTC_CENTURY	0x32

 /* Alarm time indices in RTC RAM */
 #define RTC_ALARM_SEC	0x01
 #define RTC_ALARM_MIN	0x03
 #define RTC_ALARM_HOUR	0x05

 /* Registers A-D indeces in RTC RAM */
 #define RTC_REG_A	0x0A
 #define RTC_REG_B	0x0B
 #define RTC_REG_C	0x0C
 #define RTC_REG_D	0x0D

 #define RTC_UIP		RTC_REG_A
 #define RTC_DATA	RTC_REG_B
 #define RTC_FLAG	RTC_REG_C

 /* Alarm don't case state */
 #define RTC_ALARM_DC	0xFF

 /* Update In Progress bit in REG_A */
 #define RTC_UIP_BIT	BIT(7)

 /* Update Cycle Inhibit bit in REG_B */
 #define RTC_UCI_BIT	BIT(7)

 /* Periodic Interrupt Enable bit in REG_B */
 #define RTC_PIE_BIT	BIT(6)

 /* Alarm Interrupt Enable bit in REG_B */
 #define RTC_AIE_BIT	BIT(5)

 /* Update-ended Interrupt Enable bit in REG_B */
 #define RTC_UIE_BIT	BIT(4)

 /* Data mode bit in  REG_B */
 #define RTC_DMODE_BIT	BIT(2)

 /* Hour Format bit in REG_B */
 #define RTC_HFORMAT_BIT	BIT(1)

 /* Daylight Savings Enable Format bit in REG_B */
 #define RTC_DSE_BIT	BIT(0)

 /* Interrupt Request Flag bit in REG_C */
 #define RTC_IRF_BIT	BIT(7)

 /* Periodic Flag bit in REG_C */
 #define RTC_PF_BIT	BIT(6)

 /* Alarm Flag bit in REG_C */
 #define RTC_AF_BIT	BIT(5)

 /* Update-end Flag bit in REG_C */
 #define RTC_UEF_BIT	BIT(4)

 /* VRT bit in REG_D */
 #define RTC_VRT_BIT	BIT(7)

 /* Month day Alarm bits in REG_D */
 #define RTC_MDAY_ALARM	BIT_MASK(5)

 /* Maximum and Minimum values of time */
 #define MIN_SEC		0
 #define MAX_SEC		59
 #define MIN_MIN		0
 #define MAX_MIN		59
 #define MIN_HOUR	0
 #define MAX_HOUR	23
 #define MAX_WDAY	7
 #define MIN_WDAY	1
 #define MAX_MDAY	31
 #define MIN_MDAY	1
 #define MAX_MON		12
 #define MIN_MON		1
 #define MIN_YEAR_DIFF	0 /* YEAR - 1900 */
 #define MAX_YEAR_DIFF	99 /* YEAR - 1999 */

 /* Input clock frequency mapped to divider bits */
 #define RTC_IN_CLK_DIV_BITS_4194304 (0)
 #define RTC_IN_CLK_DIV_BITS_1048576 (1 << 4)
 #define RTC_IN_CLK_DIV_BITS_32768   (2 << 4)

 struct rtc_mc146818_data {
 	struct k_spinlock lock;
 	bool alarm_pending;
 	rtc_alarm_callback cb;
 	void *cb_data;
 	rtc_update_callback update_cb;
 	void *update_cb_data;
 };

 static uint8_t rtc_read(int reg)
 {
 	uint8_t value;

 	sys_out8(reg, RTC_STD_INDEX);
 	value = sys_in8(RTC_STD_TARGET);

 	return value;
 }

 static void rtc_write(int reg, uint8_t value)
 {
 	sys_out8(reg, RTC_STD_INDEX);
 	sys_out8(value, RTC_STD_TARGET);
 }

 static bool rtc_mc146818_validate_time(const struct rtc_time *timeptr)
 {
 	if (timeptr->tm_sec < MIN_SEC || timeptr->tm_sec > MAX_SEC) {
 		return false;
 	}
 	if (timeptr->tm_min < MIN_MIN || timeptr->tm_min > MAX_MIN) {
 		return false;
 	}
 	if (timeptr->tm_hour < MIN_HOUR || timeptr->tm_hour > MAX_HOUR) {
 		return false;
 	}
 	if (timeptr->tm_wday + 1 < MIN_WDAY || timeptr->tm_wday + 1 > MAX_WDAY) {
 		return false;
 	}
 	if (timeptr->tm_mday < MIN_MDAY || timeptr->tm_mday > MAX_MDAY) {
 		return false;
 	}
 	if (timeptr->tm_mon + 1 < MIN_MON || timeptr->tm_mon + 1 > MAX_MON) {
 		return false;
 	}
 	if (timeptr->tm_year - 70 < MIN_YEAR_DIFF || timeptr->tm_year - 70 > MAX_YEAR_DIFF) {
 		return false;
 	}
 	return true;
 }

 static int rtc_mc146818_set_time(const struct device *dev, const struct rtc_time *timeptr)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	uint8_t value;
 	int year;
 	int cent;
 	int ret;

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	if (timeptr == NULL) {
 		ret = -EINVAL;
 		goto out;
 	}

 	/* Check time valid */
 	if (!rtc_mc146818_validate_time(timeptr)) {
 		ret = -EINVAL;
 		goto out;
 	}

 	value = rtc_read(RTC_DATA);
 	rtc_write(RTC_DATA, value | RTC_UCI_BIT);

 	year = (1900 + timeptr->tm_year) % 100;
 	cent = (1900 + timeptr->tm_year) / 100;

 	rtc_write(RTC_SEC, (uint8_t)timeptr->tm_sec);
 	rtc_write(RTC_MIN, (uint8_t)timeptr->tm_min);
 	rtc_write(RTC_HOUR, (uint8_t)timeptr->tm_hour);
 	rtc_write(RTC_WDAY, (uint8_t)timeptr->tm_wday);
 	rtc_write(RTC_MDAY, (uint8_t)timeptr->tm_mday);
 	rtc_write(RTC_MONTH, (uint8_t)timeptr->tm_mon + 1);
 	rtc_write(RTC_YEAR, year);
 	rtc_write(RTC_CENTURY, cent);

 	value &= (~RTC_UCI_BIT);
 	rtc_write(RTC_DATA, value);
 	ret = 0;
 out:
 	k_spin_unlock(&dev_data->lock, key);
 	return ret;
 }

 static int rtc_mc146818_get_time(const struct device *dev, struct rtc_time  *timeptr)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	int ret;
 	uint8_t cent;
 	uint8_t year;
 	uint8_t value;

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	/* Validate arguments */
 	if (timeptr == NULL) {
 		ret = -EINVAL;
 		goto out;
 	}

 	if (!(rtc_read(RTC_REG_D) & RTC_VRT_BIT)) {
 		ret = -ENODATA;
 		goto out;
 	}

 	while (rtc_read(RTC_UIP) & RTC_UIP_BIT) {
 		continue;
 	}

 	cent = rtc_read(RTC_CENTURY);
 	year = rtc_read(RTC_YEAR);
 	timeptr->tm_mon = rtc_read(RTC_MONTH) - 1;
 	timeptr->tm_mday = rtc_read(RTC_MDAY);
 	timeptr->tm_wday = rtc_read(RTC_WDAY) - 1;
 	timeptr->tm_hour = rtc_read(RTC_HOUR);
 	timeptr->tm_min = rtc_read(RTC_MIN);
 	timeptr->tm_sec = rtc_read(RTC_SEC);

 	timeptr->tm_year = 100 * (int)cent + year - 1900;

 	timeptr->tm_nsec = 0;
 	timeptr->tm_yday = 0;
 	value = rtc_read(RTC_DATA);

 	/* Check time valid */
 	if (!rtc_mc146818_validate_time(timeptr)) {
 		ret = -ENODATA;
 		goto out;
 	}
 	ret = 0;
 out:
 	k_spin_unlock(&dev_data->lock, key);
 	return ret;
 }

 #if defined(CONFIG_RTC_ALARM)
 static bool rtc_mc146818_validate_alarm(const struct rtc_time *timeptr, uint32_t mask)
 {
 	if ((mask & RTC_ALARM_TIME_MASK_SECOND) &&
 	    (timeptr->tm_sec < MIN_SEC || timeptr->tm_sec > MAX_SEC)) {
 		return false;
 	}

 	if ((mask & RTC_ALARM_TIME_MASK_MINUTE) &&
 	    (timeptr->tm_min < MIN_MIN || timeptr->tm_min > MAX_MIN)) {
 		return false;
 	}

 	if ((mask & RTC_ALARM_TIME_MASK_HOUR) &&
 	    (timeptr->tm_hour < MIN_HOUR || timeptr->tm_hour > MAX_HOUR)) {
 		return false;
 	}

 	return true;
 }

 static int rtc_mc146818_alarm_get_supported_fields(const struct device *dev, uint16_t id,
 						   uint16_t *mask)
 {
 	ARG_UNUSED(dev);

 	if (id != 0) {
 		return -EINVAL;
 	}

 	(*mask) = (RTC_ALARM_TIME_MASK_SECOND
 		   | RTC_ALARM_TIME_MASK_MINUTE
 		   | RTC_ALARM_TIME_MASK_HOUR);

 	return 0;
 }

 static int rtc_mc146818_alarm_set_time(const struct device *dev, uint16_t id, uint16_t mask,
 				       const struct rtc_time *timeptr)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	int ret;

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	if (id != 0) {
 		ret = -EINVAL;
 		goto out;
 	}

 	if ((mask > 0) && (timeptr == NULL)) {
 		ret = -EINVAL;
 		goto out;
 	}

 	/* Check time valid */
 	if (!rtc_mc146818_validate_alarm(timeptr, mask)) {
 		ret = -EINVAL;
 		goto out;
 	}

 	if (mask & RTC_ALARM_TIME_MASK_SECOND) {
 		rtc_write(RTC_ALARM_SEC, timeptr->tm_sec);
 	} else {
 		rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
 	}

 	if (mask & RTC_ALARM_TIME_MASK_MINUTE) {
 		rtc_write(RTC_ALARM_MIN, timeptr->tm_min);
 	} else {
 		rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
 	}
 	if (mask & RTC_ALARM_TIME_MASK_HOUR) {
 		rtc_write(RTC_ALARM_HOUR, timeptr->tm_hour);
 	} else {
 		rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
 	}

 	rtc_write(RTC_DATA, rtc_read(RTC_DATA) | RTC_AIE_BIT);
 	ret = 0;
 out:
 	k_spin_unlock(&dev_data->lock, key);
 	return ret;
 }

 static int rtc_mc146818_alarm_get_time(const struct device *dev, uint16_t id, uint16_t *mask,
 				   struct rtc_time *timeptr)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	uint8_t value;
 	int ret;

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	if (id != 0) {
 		ret = -EINVAL;
 		goto out;
 	}

 	if (timeptr == NULL) {
 		ret = -EINVAL;
 		goto out;
 	}

 	(*mask) = 0;

 	value = rtc_read(RTC_ALARM_SEC);
 	if (value <= MAX_SEC) {
 		timeptr->tm_sec = value;
 		(*mask) |= RTC_ALARM_TIME_MASK_SECOND;
 	}

 	value = rtc_read(RTC_ALARM_MIN);
 	if (value <= MAX_SEC) {
 		timeptr->tm_min = value;
 		(*mask) |= RTC_ALARM_TIME_MASK_MINUTE;
 	}

 	value = rtc_read(RTC_ALARM_HOUR);
 	if (value <= MAX_SEC) {
 		timeptr->tm_hour = value;
 		(*mask) |= RTC_ALARM_TIME_MASK_HOUR;
 	}

 	ret = 0;
 out:
 	k_spin_unlock(&dev_data->lock, key);
 	return ret;
 }

 static int rtc_mc146818_alarm_set_callback(const struct device *dev, uint16_t id,
 				       rtc_alarm_callback callback, void *user_data)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;

 	if (id != 0) {
 		return -EINVAL;
 	}

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	dev_data->cb = callback;
 	dev_data->cb_data = user_data;

 	if (callback != NULL) {
 		/* Enable Alarm callback */
 		rtc_write(RTC_DATA, (rtc_read(RTC_DATA) | RTC_AIE_BIT));
 	} else {
 		/* Disable Alarm callback */
 		rtc_write(RTC_DATA, (rtc_read(RTC_DATA) & (~RTC_AIE_BIT)));
 	}

 	k_spin_unlock(&dev_data->lock, key);
 	return 0;
 }

 static int rtc_mc146818_alarm_is_pending(const struct device *dev, uint16_t id)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	int ret;

 	if (id != 0) {
 		return -EINVAL;
 	}

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	ret = dev_data->alarm_pending ? 1 : 0;
 	dev_data->alarm_pending = false;

 	k_spin_unlock(&dev_data->lock, key);
 	return ret;
 }
 #endif /* CONFIG_RTC_ALARM */

 #if defined(CONFIG_RTC_UPDATE)
 static int rtc_mc146818_update_set_callback(const struct device *dev,
 					rtc_update_callback callback, void *user_data)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;

 	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

 	dev_data->update_cb = callback;
 	dev_data->update_cb_data = user_data;

 	if (callback != NULL) {
 		/* Enable update callback */
 		rtc_write(RTC_DATA, (rtc_read(RTC_DATA) | RTC_UIE_BIT));
 	} else {
 		/* Disable update callback */
 		rtc_write(RTC_DATA, (rtc_read(RTC_DATA) & (~RTC_UIE_BIT)));
 	}


 	k_spin_unlock(&dev_data->lock, key);
 	return 0;
 }

 #endif /* CONFIG_RTC_UPDATE */

 static void rtc_mc146818_isr(const struct device *dev)
 {
 	struct rtc_mc146818_data * const dev_data = dev->data;
 	uint8_t regc;

 	ARG_UNUSED(dev_data);

 	/* Read register, which clears the register */
 	regc = rtc_read(RTC_FLAG);

 #if defined(CONFIG_RTC_ALARM)
 	if (regc & RTC_AF_BIT) {
 		if (dev_data->cb) {
 			dev_data->cb(dev, 0, dev_data->cb_data);
 			dev_data->alarm_pending = false;
 		} else {
 			dev_data->alarm_pending = true;
 		}
 	}
 #endif

 #if defined(CONFIG_RTC_UPDATE)
 	if (regc & RTC_UEF_BIT) {
 		if (dev_data->update_cb) {
 			dev_data->update_cb(dev, dev_data->update_cb_data);
 		}
 	}
 #endif
 }

 static const struct rtc_driver_api rtc_mc146818_driver_api = {
 	.set_time = rtc_mc146818_set_time,
 	.get_time = rtc_mc146818_get_time,
 #if defined(CONFIG_RTC_ALARM)
 	.alarm_get_supported_fields = rtc_mc146818_alarm_get_supported_fields,
 	.alarm_set_time = rtc_mc146818_alarm_set_time,
 	.alarm_get_time = rtc_mc146818_alarm_get_time,
 	.alarm_is_pending = rtc_mc146818_alarm_is_pending,
 	.alarm_set_callback = rtc_mc146818_alarm_set_callback,
 #endif /* CONFIG_RTC_ALARM */

 #if defined(CONFIG_RTC_UPDATE)
 	.update_set_callback = rtc_mc146818_update_set_callback,
 #endif /* CONFIG_RTC_UPDATE */
 };

 #define RTC_MC146818_INIT_FN_DEFINE(n)						\
 	static int rtc_mc146818_init##n(const struct device *dev)		\
 	{									\
 		rtc_write(RTC_REG_A,						\
 			  _CONCAT(RTC_IN_CLK_DIV_BITS_,				\
 				  DT_INST_PROP(n, clock_frequency)));		\
 										\
 		rtc_write(RTC_REG_B, RTC_DMODE_BIT | RTC_HFORMAT_BIT);		\
 										\
 		IRQ_CONNECT(DT_INST_IRQN(0),					\
 				DT_INST_IRQ(0, priority),			\
 				rtc_mc146818_isr, DEVICE_DT_INST_GET(n),	\
 				DT_INST_IRQ(0, sense));				\
 										\
 		irq_enable(DT_INST_IRQN(0));					\
 										\
 		return 0;							\
 	}

 #define RTC_MC146818_DEV_CFG(inst)						\
 	struct rtc_mc146818_data rtc_mc146818_data##inst;			\
 										\
 	RTC_MC146818_INIT_FN_DEFINE(inst)					\
 										\
 	DEVICE_DT_INST_DEFINE(inst, &rtc_mc146818_init##inst, NULL,		\
 			      &rtc_mc146818_data##inst, NULL, POST_KERNEL,	\
 			      CONFIG_RTC_INIT_PRIORITY,				\
 			      &rtc_mc146818_driver_api);			\

 DT_INST_FOREACH_STATUS_OKAY(RTC_MC146818_DEV_CFG)
	/*
	* Copyright (c) 2023 Intel Corporation.
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#define DT_DRV_COMPAT motorola_mc146818

	#include <errno.h>
	#include <zephyr/device.h>
	#include <zephyr/kernel.h>
	#include <zephyr/init.h>
	#include <zephyr/sys/util.h>
	#include <zephyr/spinlock.h>
	#include <zephyr/devicetree.h>
	#include <zephyr/drivers/rtc.h>
	#include <zephyr/sys/sys_io.h>

	#define RTC_STD_INDEX (DT_INST_REG_ADDR_BY_IDX(0, 0))
	#define RTC_STD_TARGET (DT_INST_REG_ADDR_BY_IDX(0, 1))

	/* Time indices in RTC RAM */
	#define RTC_SEC 0x00
	#define RTC_MIN 0x02
	#define RTC_HOUR 0x04

	/* Day of week index in RTC RAM */
	#define RTC_WDAY 0x06

	/* Day of month index in RTC RAM */
	#define RTC_MDAY 0x07

	/* Month and year index in RTC RAM */
	#define RTC_MONTH 0x08
	#define RTC_YEAR 0x09

	/* Y2K Bugfix */
	#define RTC_CENTURY 0x32

	/* Alarm time indices in RTC RAM */
	#define RTC_ALARM_SEC 0x01
	#define RTC_ALARM_MIN 0x03
	#define RTC_ALARM_HOUR 0x05

	/* Registers A-D indeces in RTC RAM */
	#define RTC_REG_A 0x0A
	#define RTC_REG_B 0x0B
	#define RTC_REG_C 0x0C
	#define RTC_REG_D 0x0D

	#define RTC_UIP RTC_REG_A
	#define RTC_DATA RTC_REG_B
	#define RTC_FLAG RTC_REG_C

	/* Alarm don't case state */
	#define RTC_ALARM_DC 0xFF

	/* Update In Progress bit in REG_A */
	#define RTC_UIP_BIT BIT(7)

	/* Update Cycle Inhibit bit in REG_B */
	#define RTC_UCI_BIT BIT(7)

	/* Periodic Interrupt Enable bit in REG_B */
	#define RTC_PIE_BIT BIT(6)

	/* Alarm Interrupt Enable bit in REG_B */
	#define RTC_AIE_BIT BIT(5)

	/* Update-ended Interrupt Enable bit in REG_B */
	#define RTC_UIE_BIT BIT(4)

	/* Data mode bit in REG_B */
	#define RTC_DMODE_BIT BIT(2)

	/* Hour Format bit in REG_B */
	#define RTC_HFORMAT_BIT BIT(1)

	/* Daylight Savings Enable Format bit in REG_B */
	#define RTC_DSE_BIT BIT(0)

	/* Interrupt Request Flag bit in REG_C */
	#define RTC_IRF_BIT BIT(7)

	/* Periodic Flag bit in REG_C */
	#define RTC_PF_BIT BIT(6)

	/* Alarm Flag bit in REG_C */
	#define RTC_AF_BIT BIT(5)

	/* Update-end Flag bit in REG_C */
	#define RTC_UEF_BIT BIT(4)

	/* VRT bit in REG_D */
	#define RTC_VRT_BIT BIT(7)

	/* Month day Alarm bits in REG_D */
	#define RTC_MDAY_ALARM BIT_MASK(5)

	/* Maximum and Minimum values of time */
	#define MIN_SEC 0
	#define MAX_SEC 59
	#define MIN_MIN 0
	#define MAX_MIN 59
	#define MIN_HOUR 0
	#define MAX_HOUR 23
	#define MAX_WDAY 7
	#define MIN_WDAY 1
	#define MAX_MDAY 31
	#define MIN_MDAY 1
	#define MAX_MON 12
	#define MIN_MON 1
	#define MIN_YEAR_DIFF 0 /* YEAR - 1900 */
	#define MAX_YEAR_DIFF 99 /* YEAR - 1999 */

	/* Input clock frequency mapped to divider bits */
	#define RTC_IN_CLK_DIV_BITS_4194304 (0)
	#define RTC_IN_CLK_DIV_BITS_1048576 (1 << 4)
	#define RTC_IN_CLK_DIV_BITS_32768 (2 << 4)

	struct rtc_mc146818_data {
	struct k_spinlock lock;
	bool alarm_pending;
	rtc_alarm_callback cb;
	void *cb_data;
	rtc_update_callback update_cb;
	void *update_cb_data;
	};

	static uint8_t rtc_read(int reg)
	{
	uint8_t value;

	sys_out8(reg, RTC_STD_INDEX);
	value = sys_in8(RTC_STD_TARGET);

	return value;
	}

	static void rtc_write(int reg, uint8_t value)
	{
	sys_out8(reg, RTC_STD_INDEX);
	sys_out8(value, RTC_STD_TARGET);
	}

	static bool rtc_mc146818_validate_time(const struct rtc_time *timeptr)
	{
	if (timeptr->tm_sec < MIN_SEC \|\| timeptr->tm_sec > MAX_SEC) {
	return false;
	}
	if (timeptr->tm_min < MIN_MIN \|\| timeptr->tm_min > MAX_MIN) {
	return false;
	}
	if (timeptr->tm_hour < MIN_HOUR \|\| timeptr->tm_hour > MAX_HOUR) {
	return false;
	}
	if (timeptr->tm_wday + 1 < MIN_WDAY \|\| timeptr->tm_wday + 1 > MAX_WDAY) {
	return false;
	}
	if (timeptr->tm_mday < MIN_MDAY \|\| timeptr->tm_mday > MAX_MDAY) {
	return false;
	}
	if (timeptr->tm_mon + 1 < MIN_MON \|\| timeptr->tm_mon + 1 > MAX_MON) {
	return false;
	}
	if (timeptr->tm_year - 70 < MIN_YEAR_DIFF \|\| timeptr->tm_year - 70 > MAX_YEAR_DIFF) {
	return false;
	}
	return true;
	}

	static int rtc_mc146818_set_time(const struct device dev, const struct rtc_time timeptr)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	uint8_t value;
	int year;
	int cent;
	int ret;

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	if (timeptr == NULL) {
	ret = -EINVAL;
	goto out;
	}

	/* Check time valid */
	if (!rtc_mc146818_validate_time(timeptr)) {
	ret = -EINVAL;
	goto out;
	}

	value = rtc_read(RTC_DATA);
	rtc_write(RTC_DATA, value \| RTC_UCI_BIT);

	year = (1900 + timeptr->tm_year) % 100;
	cent = (1900 + timeptr->tm_year) / 100;

	rtc_write(RTC_SEC, (uint8_t)timeptr->tm_sec);
	rtc_write(RTC_MIN, (uint8_t)timeptr->tm_min);
	rtc_write(RTC_HOUR, (uint8_t)timeptr->tm_hour);
	rtc_write(RTC_WDAY, (uint8_t)timeptr->tm_wday);
	rtc_write(RTC_MDAY, (uint8_t)timeptr->tm_mday);
	rtc_write(RTC_MONTH, (uint8_t)timeptr->tm_mon + 1);
	rtc_write(RTC_YEAR, year);
	rtc_write(RTC_CENTURY, cent);

	value &= (~RTC_UCI_BIT);
	rtc_write(RTC_DATA, value);
	ret = 0;
	out:
	k_spin_unlock(&dev_data->lock, key);
	return ret;
	}

	static int rtc_mc146818_get_time(const struct device dev, struct rtc_time timeptr)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	int ret;
	uint8_t cent;
	uint8_t year;
	uint8_t value;

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	/* Validate arguments */
	if (timeptr == NULL) {
	ret = -EINVAL;
	goto out;
	}

	if (!(rtc_read(RTC_REG_D) & RTC_VRT_BIT)) {
	ret = -ENODATA;
	goto out;
	}

	while (rtc_read(RTC_UIP) & RTC_UIP_BIT) {
	continue;
	}

	cent = rtc_read(RTC_CENTURY);
	year = rtc_read(RTC_YEAR);
	timeptr->tm_mon = rtc_read(RTC_MONTH) - 1;
	timeptr->tm_mday = rtc_read(RTC_MDAY);
	timeptr->tm_wday = rtc_read(RTC_WDAY) - 1;
	timeptr->tm_hour = rtc_read(RTC_HOUR);
	timeptr->tm_min = rtc_read(RTC_MIN);
	timeptr->tm_sec = rtc_read(RTC_SEC);

	timeptr->tm_year = 100 * (int)cent + year - 1900;

	timeptr->tm_nsec = 0;
	timeptr->tm_yday = 0;
	value = rtc_read(RTC_DATA);

	/* Check time valid */
	if (!rtc_mc146818_validate_time(timeptr)) {
	ret = -ENODATA;
	goto out;
	}
	ret = 0;
	out:
	k_spin_unlock(&dev_data->lock, key);
	return ret;
	}

	#if defined(CONFIG_RTC_ALARM)
	static bool rtc_mc146818_validate_alarm(const struct rtc_time *timeptr, uint32_t mask)
	{
	if ((mask & RTC_ALARM_TIME_MASK_SECOND) &&
	(timeptr->tm_sec < MIN_SEC \|\| timeptr->tm_sec > MAX_SEC)) {
	return false;
	}

	if ((mask & RTC_ALARM_TIME_MASK_MINUTE) &&
	(timeptr->tm_min < MIN_MIN \|\| timeptr->tm_min > MAX_MIN)) {
	return false;
	}

	if ((mask & RTC_ALARM_TIME_MASK_HOUR) &&
	(timeptr->tm_hour < MIN_HOUR \|\| timeptr->tm_hour > MAX_HOUR)) {
	return false;
	}

	return true;
	}

	static int rtc_mc146818_alarm_get_supported_fields(const struct device *dev, uint16_t id,
	uint16_t *mask)
	{
	ARG_UNUSED(dev);

	if (id != 0) {
	return -EINVAL;
	}

	(*mask) = (RTC_ALARM_TIME_MASK_SECOND
	\| RTC_ALARM_TIME_MASK_MINUTE
	\| RTC_ALARM_TIME_MASK_HOUR);

	return 0;
	}

	static int rtc_mc146818_alarm_set_time(const struct device *dev, uint16_t id, uint16_t mask,
	const struct rtc_time *timeptr)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	int ret;

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	if (id != 0) {
	ret = -EINVAL;
	goto out;
	}

	if ((mask > 0) && (timeptr == NULL)) {
	ret = -EINVAL;
	goto out;
	}

	/* Check time valid */
	if (!rtc_mc146818_validate_alarm(timeptr, mask)) {
	ret = -EINVAL;
	goto out;
	}

	if (mask & RTC_ALARM_TIME_MASK_SECOND) {
	rtc_write(RTC_ALARM_SEC, timeptr->tm_sec);
	} else {
	rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
	}

	if (mask & RTC_ALARM_TIME_MASK_MINUTE) {
	rtc_write(RTC_ALARM_MIN, timeptr->tm_min);
	} else {
	rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
	}
	if (mask & RTC_ALARM_TIME_MASK_HOUR) {
	rtc_write(RTC_ALARM_HOUR, timeptr->tm_hour);
	} else {
	rtc_write(RTC_ALARM_SEC, RTC_ALARM_DC);
	}

	rtc_write(RTC_DATA, rtc_read(RTC_DATA) \| RTC_AIE_BIT);
	ret = 0;
	out:
	k_spin_unlock(&dev_data->lock, key);
	return ret;
	}

	static int rtc_mc146818_alarm_get_time(const struct device dev, uint16_t id, uint16_t mask,
	struct rtc_time *timeptr)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	uint8_t value;
	int ret;

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	if (id != 0) {
	ret = -EINVAL;
	goto out;
	}

	if (timeptr == NULL) {
	ret = -EINVAL;
	goto out;
	}

	(*mask) = 0;

	value = rtc_read(RTC_ALARM_SEC);
	if (value <= MAX_SEC) {
	timeptr->tm_sec = value;
	(*mask) \|= RTC_ALARM_TIME_MASK_SECOND;
	}

	value = rtc_read(RTC_ALARM_MIN);
	if (value <= MAX_SEC) {
	timeptr->tm_min = value;
	(*mask) \|= RTC_ALARM_TIME_MASK_MINUTE;
	}

	value = rtc_read(RTC_ALARM_HOUR);
	if (value <= MAX_SEC) {
	timeptr->tm_hour = value;
	(*mask) \|= RTC_ALARM_TIME_MASK_HOUR;
	}

	ret = 0;
	out:
	k_spin_unlock(&dev_data->lock, key);
	return ret;
	}

	static int rtc_mc146818_alarm_set_callback(const struct device *dev, uint16_t id,
	rtc_alarm_callback callback, void *user_data)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;

	if (id != 0) {
	return -EINVAL;
	}

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	dev_data->cb = callback;
	dev_data->cb_data = user_data;

	if (callback != NULL) {
	/* Enable Alarm callback */
	rtc_write(RTC_DATA, (rtc_read(RTC_DATA) \| RTC_AIE_BIT));
	} else {
	/* Disable Alarm callback */
	rtc_write(RTC_DATA, (rtc_read(RTC_DATA) & (~RTC_AIE_BIT)));
	}

	k_spin_unlock(&dev_data->lock, key);
	return 0;
	}

	static int rtc_mc146818_alarm_is_pending(const struct device *dev, uint16_t id)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	int ret;

	if (id != 0) {
	return -EINVAL;
	}

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	ret = dev_data->alarm_pending ? 1 : 0;
	dev_data->alarm_pending = false;

	k_spin_unlock(&dev_data->lock, key);
	return ret;
	}
	#endif /* CONFIG_RTC_ALARM */

	#if defined(CONFIG_RTC_UPDATE)
	static int rtc_mc146818_update_set_callback(const struct device *dev,
	rtc_update_callback callback, void *user_data)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;

	k_spinlock_key_t key = k_spin_lock(&dev_data->lock);

	dev_data->update_cb = callback;
	dev_data->update_cb_data = user_data;

	if (callback != NULL) {
	/* Enable update callback */
	rtc_write(RTC_DATA, (rtc_read(RTC_DATA) \| RTC_UIE_BIT));
	} else {
	/* Disable update callback */
	rtc_write(RTC_DATA, (rtc_read(RTC_DATA) & (~RTC_UIE_BIT)));
	}


	k_spin_unlock(&dev_data->lock, key);
	return 0;
	}

	#endif /* CONFIG_RTC_UPDATE */

	static void rtc_mc146818_isr(const struct device *dev)
	{
	struct rtc_mc146818_data * const dev_data = dev->data;
	uint8_t regc;

	ARG_UNUSED(dev_data);

	/* Read register, which clears the register */
	regc = rtc_read(RTC_FLAG);

	#if defined(CONFIG_RTC_ALARM)
	if (regc & RTC_AF_BIT) {
	if (dev_data->cb) {
	dev_data->cb(dev, 0, dev_data->cb_data);
	dev_data->alarm_pending = false;
	} else {
	dev_data->alarm_pending = true;
	}
	}
	#endif

	#if defined(CONFIG_RTC_UPDATE)
	if (regc & RTC_UEF_BIT) {
	if (dev_data->update_cb) {
	dev_data->update_cb(dev, dev_data->update_cb_data);
	}
	}
	#endif
	}

	static const struct rtc_driver_api rtc_mc146818_driver_api = {
	.set_time = rtc_mc146818_set_time,
	.get_time = rtc_mc146818_get_time,
	#if defined(CONFIG_RTC_ALARM)
	.alarm_get_supported_fields = rtc_mc146818_alarm_get_supported_fields,
	.alarm_set_time = rtc_mc146818_alarm_set_time,
	.alarm_get_time = rtc_mc146818_alarm_get_time,
	.alarm_is_pending = rtc_mc146818_alarm_is_pending,
	.alarm_set_callback = rtc_mc146818_alarm_set_callback,
	#endif /* CONFIG_RTC_ALARM */

	#if defined(CONFIG_RTC_UPDATE)
	.update_set_callback = rtc_mc146818_update_set_callback,
	#endif /* CONFIG_RTC_UPDATE */
	};

	#define RTC_MC146818_INIT_FN_DEFINE(n) \
	static int rtc_mc146818_init##n(const struct device *dev) \
	{ \
	rtc_write(RTC_REG_A, \
	_CONCAT(RTC_IN_CLK_DIV_BITS_, \
	DT_INST_PROP(n, clock_frequency))); \
	\
	rtc_write(RTC_REG_B, RTC_DMODE_BIT \| RTC_HFORMAT_BIT); \
	\
	IRQ_CONNECT(DT_INST_IRQN(0), \
	DT_INST_IRQ(0, priority), \
	rtc_mc146818_isr, DEVICE_DT_INST_GET(n), \
	DT_INST_IRQ(0, sense)); \
	\
	irq_enable(DT_INST_IRQN(0)); \
	\
	return 0; \
	}

	#define RTC_MC146818_DEV_CFG(inst) \
	struct rtc_mc146818_data rtc_mc146818_data##inst; \
	\
	RTC_MC146818_INIT_FN_DEFINE(inst) \
	\
	DEVICE_DT_INST_DEFINE(inst, &rtc_mc146818_init##inst, NULL, \
	&rtc_mc146818_data##inst, NULL, POST_KERNEL, \
	CONFIG_RTC_INIT_PRIORITY, \
	&rtc_mc146818_driver_api); \

	DT_INST_FOREACH_STATUS_OKAY(RTC_MC146818_DEV_CFG)