drivers/rtc/rv3029.c - manifest_repos/u-boot - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
  *
  * Based on a the Linux rtc-rv3029c2.c driver written by:
  *   Gregory Hermant <gregory.hermant@calao-systems.com>
  *   Michael Buesch <m@bues.ch>
  */

 #include <common.h>
 #include <command.h>
 #include <dm.h>
 #include <i2c.h>
 #include <rtc.h>

 #define RTC_RV3029_PAGE_LEN             7

 /* control section */
 #define RV3029_ONOFF_CTRL		0x00
 #define RV3029_ONOFF_CTRL_WE		BIT(0)
 #define RV3029_ONOFF_CTRL_TE		BIT(1)
 #define RV3029_ONOFF_CTRL_TAR		BIT(2)
 #define RV3029_ONOFF_CTRL_EERE		BIT(3)
 #define RV3029_ONOFF_CTRL_SRON		BIT(4)
 #define RV3029_ONOFF_CTRL_TD0		BIT(5)
 #define RV3029_ONOFF_CTRL_TD1		BIT(6)
 #define RV3029_ONOFF_CTRL_CLKINT	BIT(7)
 #define RV3029_IRQ_CTRL			0x01
 #define RV3029_IRQ_CTRL_AIE		BIT(0)
 #define RV3029_IRQ_CTRL_TIE		BIT(1)
 #define RV3029_IRQ_CTRL_V1IE		BIT(2)
 #define RV3029_IRQ_CTRL_V2IE		BIT(3)
 #define RV3029_IRQ_CTRL_SRIE		BIT(4)
 #define RV3029_IRQ_FLAGS		0x02
 #define RV3029_IRQ_FLAGS_AF		BIT(0)
 #define RV3029_IRQ_FLAGS_TF		BIT(1)
 #define RV3029_IRQ_FLAGS_V1IF		BIT(2)
 #define RV3029_IRQ_FLAGS_V2IF		BIT(3)
 #define RV3029_IRQ_FLAGS_SRF		BIT(4)
 #define RV3029_STATUS			0x03
 #define RV3029_STATUS_VLOW1		BIT(2)
 #define RV3029_STATUS_VLOW2		BIT(3)
 #define RV3029_STATUS_SR		BIT(4)
 #define RV3029_STATUS_PON		BIT(5)
 #define RV3029_STATUS_EEBUSY		BIT(7)
 #define RV3029_RST_CTRL			0x04
 #define RV3029_RST_CTRL_SYSR		BIT(4)
 #define RV3029_CONTROL_SECTION_LEN	0x05

 /* watch section */
 #define RV3029_W_SEC			0x08
 #define RV3029_W_MINUTES		0x09
 #define RV3029_W_HOURS			0x0A
 #define RV3029_REG_HR_12_24		BIT(6) /* 24h/12h mode */
 #define RV3029_REG_HR_PM		BIT(5) /* PM/AM bit in 12h mode */
 #define RV3029_W_DATE			0x0B
 #define RV3029_W_DAYS			0x0C
 #define RV3029_W_MONTHS			0x0D
 #define RV3029_W_YEARS			0x0E

 /* eeprom control section */
 #define RV3029_CONTROL_E2P_EECTRL	0x30
 #define RV3029_TRICKLE_1K		BIT(4) /* 1.5K resistance */
 #define RV3029_TRICKLE_5K		BIT(5) /* 5K   resistance */
 #define RV3029_TRICKLE_20K		BIT(6) /* 20K  resistance */
 #define RV3029_TRICKLE_80K		BIT(7) /* 80K  resistance */
 #define RV3029_TRICKLE_MASK		(RV3029_TRICKLE_1K |\
 					 RV3029_TRICKLE_5K |\
 					 RV3029_TRICKLE_20K |\
 					 RV3029_TRICKLE_80K)
 #define RV3029_TRICKLE_SHIFT		4


 static int rv3029_rtc_get(struct udevice *dev, struct rtc_time *tm)
 {
 	u8 regs[RTC_RV3029_PAGE_LEN];
 	int ret;

 	ret = dm_i2c_read(dev, RV3029_W_SEC, regs, sizeof(regs));
 	if (ret < 0) {
 		printf("%s: error reading RTC: %x\n", __func__, ret);
 		return -EIO;
 	}

 	tm->tm_sec = bcd2bin(regs[RV3029_W_SEC - RV3029_W_SEC]);
 	tm->tm_min = bcd2bin(regs[RV3029_W_MINUTES - RV3029_W_SEC]);

 	/* HR field has a more complex interpretation */
 	{
 		const u8 _hr = regs[RV3029_W_HOURS - RV3029_W_SEC];

 		if (_hr & RV3029_REG_HR_12_24) {
 			/* 12h format */
 			tm->tm_hour = bcd2bin(_hr & 0x1f);
 			if (_hr & RV3029_REG_HR_PM)	/* PM flag set */
 				tm->tm_hour += 12;
 		} else {
 			/* 24h format */
 			tm->tm_hour = bcd2bin(_hr & 0x3f);
 		}
 	}

 	tm->tm_mday = bcd2bin(regs[RV3029_W_DATE - RV3029_W_SEC]);
 	tm->tm_mon = bcd2bin(regs[RV3029_W_MONTHS - RV3029_W_SEC]) - 1;
 	/* RTC supports only years > 1999 */
 	tm->tm_year = bcd2bin(regs[RV3029_W_YEARS - RV3029_W_SEC]) + 2000;
 	tm->tm_wday = bcd2bin(regs[RV3029_W_DAYS - RV3029_W_SEC]) - 1;

 	tm->tm_yday = 0;
 	tm->tm_isdst = 0;

 	debug("%s: %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n",
 	      __func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
 	      tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);

 	return 0;
 }

 static int rv3029_rtc_set(struct udevice *dev, const struct rtc_time *tm)
 {
 	u8 regs[RTC_RV3029_PAGE_LEN];

 	debug("%s: %4d-%02d-%02d (wday=%d( %2d:%02d:%02d\n",
 	      __func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
 	      tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);


 	if (tm->tm_year < 2000) {
 		printf("%s: year %d (before 2000) not supported\n",
 		       __func__, tm->tm_year);
 		return -EINVAL;
 	}

 	regs[RV3029_W_SEC - RV3029_W_SEC] = bin2bcd(tm->tm_sec);
 	regs[RV3029_W_MINUTES - RV3029_W_SEC] = bin2bcd(tm->tm_min);
 	regs[RV3029_W_HOURS - RV3029_W_SEC] = bin2bcd(tm->tm_hour);
 	regs[RV3029_W_DATE - RV3029_W_SEC] = bin2bcd(tm->tm_mday);
 	regs[RV3029_W_MONTHS - RV3029_W_SEC] = bin2bcd(tm->tm_mon + 1);
 	regs[RV3029_W_DAYS - RV3029_W_SEC] = bin2bcd(tm->tm_wday + 1) & 0x7;
 	regs[RV3029_W_YEARS - RV3029_W_SEC] = bin2bcd(tm->tm_year - 2000);

 	return dm_i2c_write(dev, RV3029_W_SEC, regs, sizeof(regs));
 }

 static int rv3029_rtc_reset(struct udevice *dev)
 {
 	u8 ctrl = RV3029_RST_CTRL_SYSR;
 	unsigned long start;
 	const unsigned long timeout_ms = 10000;
 	int ret;

 	/* trigger the system-reset */
 	ret = dm_i2c_write(dev, RV3029_RST_CTRL, &ctrl, 1);
 	if (ret < 0)
 		return -EIO;

 	/* wait for the system-reset to complete */
 	start = get_timer(0);
 	do {
 		if (get_timer(start) > timeout_ms)
 			return -ETIMEDOUT;

 		ret = dm_i2c_read(dev, RV3029_RST_CTRL, &ctrl, 1);
 		if (ret < 0)
 			return -EIO;
 	} while (ctrl & RV3029_RST_CTRL_SYSR);

 	return 0;
 }

 static int rv3029_rtc_read8(struct udevice *dev, unsigned int reg)
 {
 	u8 data;
 	int ret;

 	ret = dm_i2c_read(dev, reg, &data, sizeof(data));
 	return ret < 0 ? ret : data;
 }

 static int rv3029_rtc_write8(struct udevice *dev, unsigned int reg, int val)
 {
 	u8 data = val;

 	return dm_i2c_write(dev, reg, &data, 1);
 }

 #if defined(OF_CONTROL)
 static int rv3029_get_sr(struct udevice *dev, u8 *buf)
 {
 	int ret = dm_i2c_read(dev, RV3029_STATUS, buf, 1);

 	if (ret < 0)
 		return -EIO;

 	dev_dbg(dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
 	return 0;
 }

 static int rv3029_set_sr(struct udevice *dev, u8 val)
 {
 	int ret;

 	ret = dm_i2c_read(dev, RV3029_STATUS, &val, 1);
 	if (ret < 0)
 		return -EIO;

 	dev_dbg(dev, "status = 0x%.2x (%d)\n", val, val);
 	return 0;
 }

 static int rv3029_eeprom_busywait(struct udevice *dev)
 {
 	int i, ret;
 	u8 sr;

 	for (i = 100; i > 0; i--) {
 		ret = rv3029_get_sr(dev, &sr);
 		if (ret < 0)
 			break;
 		if (!(sr & RV3029_STATUS_EEBUSY))
 			break;
 		udelay(10000);
 	}
 	if (i <= 0) {
 		dev_err(dev, "EEPROM busy wait timeout.\n");
 		return -ETIMEDOUT;
 	}

 	return ret;
 }

 static int rv3029_update_bits(struct udevice *dev, u8 reg, u8 mask, u8 set)
 {
 	u8 buf;
 	int ret;

 	ret = dm_i2c_read(dev, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	if ((buf & mask) == (set && mask))
 		return 0;

 	buf = (buf & ~mask) | (set & mask);
 	ret = dm_i2c_read(dev, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	return 0;
 }

 static int rv3029_eeprom_exit(struct udevice *dev)
 {
 	/* Re-enable eeprom refresh */
 	return rv3029_update_bits(dev, RV3029_ONOFF_CTRL,
 				  RV3029_ONOFF_CTRL_EERE,
 				  RV3029_ONOFF_CTRL_EERE);
 }

 static int rv3029_eeprom_enter(struct udevice *dev)
 {
 	int ret;
 	u8 sr;

 	/* Check whether we are in the allowed voltage range. */
 	ret = rv3029_get_sr(dev, &sr);
 	if (ret < 0)
 		return ret;
 	if (sr & (RV3029_STATUS_VLOW1 | RV3029_STATUS_VLOW2)) {
 		/* We clear the bits and retry once just in case
 		 * we had a brown out in early startup.
 		 */
 		sr &= ~RV3029_STATUS_VLOW1;
 		sr &= ~RV3029_STATUS_VLOW2;
 		ret = rv3029_set_sr(dev, sr);
 		if (ret < 0)
 			return ret;
 		udelay(10000);
 		ret = rv3029_get_sr(dev, &sr);
 		if (ret < 0)
 			return ret;
 		if (sr & (RV3029_STATUS_VLOW1 | RV3029_STATUS_VLOW2)) {
 			dev_err(dev, "Supply voltage is too low to safely access the EEPROM.\n");
 			return -ENODEV;
 		}
 	}

 	/* Disable eeprom refresh. */
 	ret = rv3029_update_bits(dev,
 				 RV3029_ONOFF_CTRL, RV3029_ONOFF_CTRL_EERE, 0);
 	if (ret < 0)
 		return ret;

 	/* Wait for any previous eeprom accesses to finish. */
 	ret = rv3029_eeprom_busywait(dev);
 	if (ret < 0)
 		rv3029_eeprom_exit(dev);

 	return ret;
 }

 static int rv3029_eeprom_read(struct udevice *dev, u8 reg,
 			      u8 buf[], size_t len)
 {
 	int ret, err;

 	err = rv3029_eeprom_enter(dev);
 	if (err < 0)
 		return err;

 	ret = dm_i2c_read(dev, reg, buf, len);

 	err = rv3029_eeprom_exit(dev);
 	if (err < 0)
 		return err;

 	return ret;
 }

 static int rv3029_eeprom_write(struct udevice *dev, u8 reg,
 			       u8 const buf[], size_t len)
 {
 	int ret;
 	size_t i;
 	u8 tmp;

 	ret = rv3029_eeprom_enter(dev);
 	if (ret < 0)
 		return ret;

 	for (i = 0; i < len; i++, reg++) {
 		ret = dm_i2c_read(dev, reg, &tmp, 1);
 		if (ret < 0)
 			break;
 		if (tmp != buf[i]) {
 			ret = dm_i2c_write(dev, reg, &buf[i], 1);
 			if (ret < 0)
 				break;
 		}
 		ret = rv3029_eeprom_busywait(dev);
 		if (ret < 0)
 			break;
 	}

 	ret = rv3029_eeprom_exit(dev);
 	if (ret < 0)
 		return ret;

 	return 0;
 }

 static int rv3029_eeprom_update_bits(struct udevice *dev,
 				     u8 reg, u8 mask, u8 set)
 {
 	u8 buf;
 	int ret;

 	ret = rv3029_eeprom_read(dev, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	/*
 	 * If the EEPROM already reads the correct bitpattern, we don't need
 	 * to update it.
 	 */
 	if ((buf & mask) == (set & mask))
 		return 0;

 	buf = (buf & ~mask) | (set & mask);
 	ret = rv3029_eeprom_write(dev, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	return 0;
 }

 static void rv3029_trickle_config(struct udevice *dev)
 {
 	static const struct rv3029_trickle_tab_elem {
 		u32 r;		/* resistance in ohms */
 		u8 conf;	/* trickle config bits */
 	} rv3029_trickle_tab[] = {
 		{
 			.r	= 1076,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_5K |
 				  RV3029_TRICKLE_20K | RV3029_TRICKLE_80K,
 		}, {
 			.r	= 1091,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_5K |
 				  RV3029_TRICKLE_20K,
 		}, {
 			.r	= 1137,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_5K |
 				  RV3029_TRICKLE_80K,
 		}, {
 			.r	= 1154,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_5K,
 		}, {
 			.r	= 1371,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_20K |
 				  RV3029_TRICKLE_80K,
 		}, {
 			.r	= 1395,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_20K,
 		}, {
 			.r	= 1472,
 			.conf	= RV3029_TRICKLE_1K | RV3029_TRICKLE_80K,
 		}, {
 			.r	= 1500,
 			.conf	= RV3029_TRICKLE_1K,
 		}, {
 			.r	= 3810,
 			.conf	= RV3029_TRICKLE_5K | RV3029_TRICKLE_20K |
 				  RV3029_TRICKLE_80K,
 		}, {
 			.r	= 4000,
 			.conf	= RV3029_TRICKLE_5K | RV3029_TRICKLE_20K,
 		}, {
 			.r	= 4706,
 			.conf	= RV3029_TRICKLE_5K | RV3029_TRICKLE_80K,
 		}, {
 			.r	= 5000,
 			.conf	= RV3029_TRICKLE_5K,
 		}, {
 			.r	= 16000,
 			.conf	= RV3029_TRICKLE_20K | RV3029_TRICKLE_80K,
 		}, {
 			.r	= 20000,
 			.conf	= RV3029_TRICKLE_20K,
 		}, {
 			.r	= 80000,
 			.conf	= RV3029_TRICKLE_80K,
 		},
 	};
 	int err;
 	u32 ohms;
 	u8 trickle_set_bits = 0;

 	/* Configure the trickle charger. */
 	err = dev_read_u32(dev, "trickle-resistor-ohms", &ohms);

 	if (!err) {
 		/* Find trickle-charger config */
 		for (int i = 0; i < ARRAY_SIZE(rv3029_trickle_tab); i++)
 			if (rv3029_trickle_tab[i].r >= ohms) {
 				dev_dbg(dev, "trickle charger at %d ohms\n",
 					rv3029_trickle_tab[i].r);
 				trickle_set_bits = rv3029_trickle_tab[i].conf;
 				break;
 			}
 	}

 	dev_dbg(dev, "trickle charger config 0x%x\n", trickle_set_bits);
 	err = rv3029_eeprom_update_bits(dev, RV3029_CONTROL_E2P_EECTRL,
 					RV3029_TRICKLE_MASK,
 					trickle_set_bits);
 	if (err < 0)
 		dev_dbg(dev, "failed to update trickle charger\n");
 }
 #else
 static inline void rv3029_trickle_config(struct udevice *dev)
 {
 }
 #endif

 static int rv3029_probe(struct udevice *dev)
 {
 	i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS |
 				DM_I2C_CHIP_WR_ADDRESS);

 	rv3029_trickle_config(dev);
 	return 0;
 }

 static const struct rtc_ops rv3029_rtc_ops = {
 	.get = rv3029_rtc_get,
 	.set = rv3029_rtc_set,
 	.read8 = rv3029_rtc_read8,
 	.write8 = rv3029_rtc_write8,
 	.reset = rv3029_rtc_reset,
 };

 static const struct udevice_id rv3029_rtc_ids[] = {
 	{ .compatible = "mc,rv3029" },
 	{ .compatible = "mc,rv3029c2" },
 	{ }
 };

 U_BOOT_DRIVER(rtc_rv3029) = {
 	.name	= "rtc-rv3029",
 	.id	= UCLASS_RTC,
 	.probe	= rv3029_probe,
 	.of_match = rv3029_rtc_ids,
 	.ops	= &rv3029_rtc_ops,
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
	*
	* Based on a the Linux rtc-rv3029c2.c driver written by:
	* Gregory Hermant <gregory.hermant@calao-systems.com>
	* Michael Buesch <m@bues.ch>
	*/

	#include <common.h>
	#include <command.h>
	#include <dm.h>
	#include <i2c.h>
	#include <rtc.h>

	#define RTC_RV3029_PAGE_LEN 7

	/* control section */
	#define RV3029_ONOFF_CTRL 0x00
	#define RV3029_ONOFF_CTRL_WE BIT(0)
	#define RV3029_ONOFF_CTRL_TE BIT(1)
	#define RV3029_ONOFF_CTRL_TAR BIT(2)
	#define RV3029_ONOFF_CTRL_EERE BIT(3)
	#define RV3029_ONOFF_CTRL_SRON BIT(4)
	#define RV3029_ONOFF_CTRL_TD0 BIT(5)
	#define RV3029_ONOFF_CTRL_TD1 BIT(6)
	#define RV3029_ONOFF_CTRL_CLKINT BIT(7)
	#define RV3029_IRQ_CTRL 0x01
	#define RV3029_IRQ_CTRL_AIE BIT(0)
	#define RV3029_IRQ_CTRL_TIE BIT(1)
	#define RV3029_IRQ_CTRL_V1IE BIT(2)
	#define RV3029_IRQ_CTRL_V2IE BIT(3)
	#define RV3029_IRQ_CTRL_SRIE BIT(4)
	#define RV3029_IRQ_FLAGS 0x02
	#define RV3029_IRQ_FLAGS_AF BIT(0)
	#define RV3029_IRQ_FLAGS_TF BIT(1)
	#define RV3029_IRQ_FLAGS_V1IF BIT(2)
	#define RV3029_IRQ_FLAGS_V2IF BIT(3)
	#define RV3029_IRQ_FLAGS_SRF BIT(4)
	#define RV3029_STATUS 0x03
	#define RV3029_STATUS_VLOW1 BIT(2)
	#define RV3029_STATUS_VLOW2 BIT(3)
	#define RV3029_STATUS_SR BIT(4)
	#define RV3029_STATUS_PON BIT(5)
	#define RV3029_STATUS_EEBUSY BIT(7)
	#define RV3029_RST_CTRL 0x04
	#define RV3029_RST_CTRL_SYSR BIT(4)
	#define RV3029_CONTROL_SECTION_LEN 0x05

	/* watch section */
	#define RV3029_W_SEC 0x08
	#define RV3029_W_MINUTES 0x09
	#define RV3029_W_HOURS 0x0A
	#define RV3029_REG_HR_12_24 BIT(6) /* 24h/12h mode */
	#define RV3029_REG_HR_PM BIT(5) /* PM/AM bit in 12h mode */
	#define RV3029_W_DATE 0x0B
	#define RV3029_W_DAYS 0x0C
	#define RV3029_W_MONTHS 0x0D
	#define RV3029_W_YEARS 0x0E

	/* eeprom control section */
	#define RV3029_CONTROL_E2P_EECTRL 0x30
	#define RV3029_TRICKLE_1K BIT(4) /* 1.5K resistance */
	#define RV3029_TRICKLE_5K BIT(5) /* 5K resistance */
	#define RV3029_TRICKLE_20K BIT(6) /* 20K resistance */
	#define RV3029_TRICKLE_80K BIT(7) /* 80K resistance */
	#define RV3029_TRICKLE_MASK (RV3029_TRICKLE_1K \|\
	RV3029_TRICKLE_5K \|\
	RV3029_TRICKLE_20K \|\
	RV3029_TRICKLE_80K)
	#define RV3029_TRICKLE_SHIFT 4


	static int rv3029_rtc_get(struct udevice dev, struct rtc_time tm)
	{
	u8 regs[RTC_RV3029_PAGE_LEN];
	int ret;

	ret = dm_i2c_read(dev, RV3029_W_SEC, regs, sizeof(regs));
	if (ret < 0) {
	printf("%s: error reading RTC: %x\n", __func__, ret);
	return -EIO;
	}

	tm->tm_sec = bcd2bin(regs[RV3029_W_SEC - RV3029_W_SEC]);
	tm->tm_min = bcd2bin(regs[RV3029_W_MINUTES - RV3029_W_SEC]);

	/* HR field has a more complex interpretation */
	{
	const u8 _hr = regs[RV3029_W_HOURS - RV3029_W_SEC];

	if (_hr & RV3029_REG_HR_12_24) {
	/* 12h format */
	tm->tm_hour = bcd2bin(_hr & 0x1f);
	if (_hr & RV3029_REG_HR_PM) /* PM flag set */
	tm->tm_hour += 12;
	} else {
	/* 24h format */
	tm->tm_hour = bcd2bin(_hr & 0x3f);
	}
	}

	tm->tm_mday = bcd2bin(regs[RV3029_W_DATE - RV3029_W_SEC]);
	tm->tm_mon = bcd2bin(regs[RV3029_W_MONTHS - RV3029_W_SEC]) - 1;
	/* RTC supports only years > 1999 */
	tm->tm_year = bcd2bin(regs[RV3029_W_YEARS - RV3029_W_SEC]) + 2000;
	tm->tm_wday = bcd2bin(regs[RV3029_W_DAYS - RV3029_W_SEC]) - 1;

	tm->tm_yday = 0;
	tm->tm_isdst = 0;

	debug("%s: %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n",
	__func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
	tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);

	return 0;
	}

	static int rv3029_rtc_set(struct udevice dev, const struct rtc_time tm)
	{
	u8 regs[RTC_RV3029_PAGE_LEN];

	debug("%s: %4d-%02d-%02d (wday=%d( %2d:%02d:%02d\n",
	__func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
	tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);


	if (tm->tm_year < 2000) {
	printf("%s: year %d (before 2000) not supported\n",
	__func__, tm->tm_year);
	return -EINVAL;
	}

	regs[RV3029_W_SEC - RV3029_W_SEC] = bin2bcd(tm->tm_sec);
	regs[RV3029_W_MINUTES - RV3029_W_SEC] = bin2bcd(tm->tm_min);
	regs[RV3029_W_HOURS - RV3029_W_SEC] = bin2bcd(tm->tm_hour);
	regs[RV3029_W_DATE - RV3029_W_SEC] = bin2bcd(tm->tm_mday);
	regs[RV3029_W_MONTHS - RV3029_W_SEC] = bin2bcd(tm->tm_mon + 1);
	regs[RV3029_W_DAYS - RV3029_W_SEC] = bin2bcd(tm->tm_wday + 1) & 0x7;
	regs[RV3029_W_YEARS - RV3029_W_SEC] = bin2bcd(tm->tm_year - 2000);

	return dm_i2c_write(dev, RV3029_W_SEC, regs, sizeof(regs));
	}

	static int rv3029_rtc_reset(struct udevice *dev)
	{
	u8 ctrl = RV3029_RST_CTRL_SYSR;
	unsigned long start;
	const unsigned long timeout_ms = 10000;
	int ret;

	/* trigger the system-reset */
	ret = dm_i2c_write(dev, RV3029_RST_CTRL, &ctrl, 1);
	if (ret < 0)
	return -EIO;

	/* wait for the system-reset to complete */
	start = get_timer(0);
	do {
	if (get_timer(start) > timeout_ms)
	return -ETIMEDOUT;

	ret = dm_i2c_read(dev, RV3029_RST_CTRL, &ctrl, 1);
	if (ret < 0)
	return -EIO;
	} while (ctrl & RV3029_RST_CTRL_SYSR);

	return 0;
	}

	static int rv3029_rtc_read8(struct udevice *dev, unsigned int reg)
	{
	u8 data;
	int ret;

	ret = dm_i2c_read(dev, reg, &data, sizeof(data));
	return ret < 0 ? ret : data;
	}

	static int rv3029_rtc_write8(struct udevice *dev, unsigned int reg, int val)
	{
	u8 data = val;

	return dm_i2c_write(dev, reg, &data, 1);
	}

	#if defined(OF_CONTROL)
	static int rv3029_get_sr(struct udevice dev, u8 buf)
	{
	int ret = dm_i2c_read(dev, RV3029_STATUS, buf, 1);

	if (ret < 0)
	return -EIO;

	dev_dbg(dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
	return 0;
	}

	static int rv3029_set_sr(struct udevice *dev, u8 val)
	{
	int ret;

	ret = dm_i2c_read(dev, RV3029_STATUS, &val, 1);
	if (ret < 0)
	return -EIO;

	dev_dbg(dev, "status = 0x%.2x (%d)\n", val, val);
	return 0;
	}

	static int rv3029_eeprom_busywait(struct udevice *dev)
	{
	int i, ret;
	u8 sr;

	for (i = 100; i > 0; i--) {
	ret = rv3029_get_sr(dev, &sr);
	if (ret < 0)
	break;
	if (!(sr & RV3029_STATUS_EEBUSY))
	break;
	udelay(10000);
	}
	if (i <= 0) {
	dev_err(dev, "EEPROM busy wait timeout.\n");
	return -ETIMEDOUT;
	}

	return ret;
	}

	static int rv3029_update_bits(struct udevice *dev, u8 reg, u8 mask, u8 set)
	{
	u8 buf;
	int ret;

	ret = dm_i2c_read(dev, reg, &buf, 1);
	if (ret < 0)
	return ret;

	if ((buf & mask) == (set && mask))
	return 0;

	buf = (buf & ~mask) \| (set & mask);
	ret = dm_i2c_read(dev, reg, &buf, 1);
	if (ret < 0)
	return ret;

	return 0;
	}

	static int rv3029_eeprom_exit(struct udevice *dev)
	{
	/* Re-enable eeprom refresh */
	return rv3029_update_bits(dev, RV3029_ONOFF_CTRL,
	RV3029_ONOFF_CTRL_EERE,
	RV3029_ONOFF_CTRL_EERE);
	}

	static int rv3029_eeprom_enter(struct udevice *dev)
	{
	int ret;
	u8 sr;

	/* Check whether we are in the allowed voltage range. */
	ret = rv3029_get_sr(dev, &sr);
	if (ret < 0)
	return ret;
	if (sr & (RV3029_STATUS_VLOW1 \| RV3029_STATUS_VLOW2)) {
	/* We clear the bits and retry once just in case
	* we had a brown out in early startup.
	*/
	sr &= ~RV3029_STATUS_VLOW1;
	sr &= ~RV3029_STATUS_VLOW2;
	ret = rv3029_set_sr(dev, sr);
	if (ret < 0)
	return ret;
	udelay(10000);
	ret = rv3029_get_sr(dev, &sr);
	if (ret < 0)
	return ret;
	if (sr & (RV3029_STATUS_VLOW1 \| RV3029_STATUS_VLOW2)) {
	dev_err(dev, "Supply voltage is too low to safely access the EEPROM.\n");
	return -ENODEV;
	}
	}

	/* Disable eeprom refresh. */
	ret = rv3029_update_bits(dev,
	RV3029_ONOFF_CTRL, RV3029_ONOFF_CTRL_EERE, 0);
	if (ret < 0)
	return ret;

	/* Wait for any previous eeprom accesses to finish. */
	ret = rv3029_eeprom_busywait(dev);
	if (ret < 0)
	rv3029_eeprom_exit(dev);

	return ret;
	}

	static int rv3029_eeprom_read(struct udevice *dev, u8 reg,
	u8 buf[], size_t len)
	{
	int ret, err;

	err = rv3029_eeprom_enter(dev);
	if (err < 0)
	return err;

	ret = dm_i2c_read(dev, reg, buf, len);

	err = rv3029_eeprom_exit(dev);
	if (err < 0)
	return err;

	return ret;
	}

	static int rv3029_eeprom_write(struct udevice *dev, u8 reg,
	u8 const buf[], size_t len)
	{
	int ret;
	size_t i;
	u8 tmp;

	ret = rv3029_eeprom_enter(dev);
	if (ret < 0)
	return ret;

	for (i = 0; i < len; i++, reg++) {
	ret = dm_i2c_read(dev, reg, &tmp, 1);
	if (ret < 0)
	break;
	if (tmp != buf[i]) {
	ret = dm_i2c_write(dev, reg, &buf[i], 1);
	if (ret < 0)
	break;
	}
	ret = rv3029_eeprom_busywait(dev);
	if (ret < 0)
	break;
	}

	ret = rv3029_eeprom_exit(dev);
	if (ret < 0)
	return ret;

	return 0;
	}

	static int rv3029_eeprom_update_bits(struct udevice *dev,
	u8 reg, u8 mask, u8 set)
	{
	u8 buf;
	int ret;

	ret = rv3029_eeprom_read(dev, reg, &buf, 1);
	if (ret < 0)
	return ret;

	/*
	* If the EEPROM already reads the correct bitpattern, we don't need
	* to update it.
	*/
	if ((buf & mask) == (set & mask))
	return 0;

	buf = (buf & ~mask) \| (set & mask);
	ret = rv3029_eeprom_write(dev, reg, &buf, 1);
	if (ret < 0)
	return ret;

	return 0;
	}

	static void rv3029_trickle_config(struct udevice *dev)
	{
	static const struct rv3029_trickle_tab_elem {
	u32 r; /* resistance in ohms */
	u8 conf; /* trickle config bits */
	} rv3029_trickle_tab[] = {
	{
	.r = 1076,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_5K \|
	RV3029_TRICKLE_20K \| RV3029_TRICKLE_80K,
	}, {
	.r = 1091,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_5K \|
	RV3029_TRICKLE_20K,
	}, {
	.r = 1137,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_5K \|
	RV3029_TRICKLE_80K,
	}, {
	.r = 1154,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_5K,
	}, {
	.r = 1371,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_20K \|
	RV3029_TRICKLE_80K,
	}, {
	.r = 1395,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_20K,
	}, {
	.r = 1472,
	.conf = RV3029_TRICKLE_1K \| RV3029_TRICKLE_80K,
	}, {
	.r = 1500,
	.conf = RV3029_TRICKLE_1K,
	}, {
	.r = 3810,
	.conf = RV3029_TRICKLE_5K \| RV3029_TRICKLE_20K \|
	RV3029_TRICKLE_80K,
	}, {
	.r = 4000,
	.conf = RV3029_TRICKLE_5K \| RV3029_TRICKLE_20K,
	}, {
	.r = 4706,
	.conf = RV3029_TRICKLE_5K \| RV3029_TRICKLE_80K,
	}, {
	.r = 5000,
	.conf = RV3029_TRICKLE_5K,
	}, {
	.r = 16000,
	.conf = RV3029_TRICKLE_20K \| RV3029_TRICKLE_80K,
	}, {
	.r = 20000,
	.conf = RV3029_TRICKLE_20K,
	}, {
	.r = 80000,
	.conf = RV3029_TRICKLE_80K,
	},
	};
	int err;
	u32 ohms;
	u8 trickle_set_bits = 0;

	/* Configure the trickle charger. */
	err = dev_read_u32(dev, "trickle-resistor-ohms", &ohms);

	if (!err) {
	/* Find trickle-charger config */
	for (int i = 0; i < ARRAY_SIZE(rv3029_trickle_tab); i++)
	if (rv3029_trickle_tab[i].r >= ohms) {
	dev_dbg(dev, "trickle charger at %d ohms\n",
	rv3029_trickle_tab[i].r);
	trickle_set_bits = rv3029_trickle_tab[i].conf;
	break;
	}
	}

	dev_dbg(dev, "trickle charger config 0x%x\n", trickle_set_bits);
	err = rv3029_eeprom_update_bits(dev, RV3029_CONTROL_E2P_EECTRL,
	RV3029_TRICKLE_MASK,
	trickle_set_bits);
	if (err < 0)
	dev_dbg(dev, "failed to update trickle charger\n");
	}
	#else
	static inline void rv3029_trickle_config(struct udevice *dev)
	{
	}
	#endif

	static int rv3029_probe(struct udevice *dev)
	{
	i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS \|
	DM_I2C_CHIP_WR_ADDRESS);

	rv3029_trickle_config(dev);
	return 0;
	}

	static const struct rtc_ops rv3029_rtc_ops = {
	.get = rv3029_rtc_get,
	.set = rv3029_rtc_set,
	.read8 = rv3029_rtc_read8,
	.write8 = rv3029_rtc_write8,
	.reset = rv3029_rtc_reset,
	};

	static const struct udevice_id rv3029_rtc_ids[] = {
	{ .compatible = "mc,rv3029" },
	{ .compatible = "mc,rv3029c2" },
	{ }
	};

	U_BOOT_DRIVER(rtc_rv3029) = {
	.name = "rtc-rv3029",
	.id = UCLASS_RTC,
	.probe = rv3029_probe,
	.of_match = rv3029_rtc_ids,
	.ops = &rv3029_rtc_ops,
	};