drivers/rtc/rtc-rv3029c2.c - kernel/msm-4.9 - Gitiles

 /*
  * Micro Crystal RV-3029 rtc class driver
  *
  * Author: Gregory Hermant <gregory.hermant@calao-systems.com>
  *         Michael Buesch <m@bues.ch>
  *
  * based on previously existing rtc class drivers
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/bcd.h>
 #include <linux/rtc.h>
 #include <linux/delay.h>
 #include <linux/of.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>


 /* Register map */
 /* 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
 #define RV3029_WATCH_SECTION_LEN	0x07

 /* alarm section */
 #define RV3029_A_SC			0x10
 #define RV3029_A_MN			0x11
 #define RV3029_A_HR			0x12
 #define RV3029_A_DT			0x13
 #define RV3029_A_DW			0x14
 #define RV3029_A_MO			0x15
 #define RV3029_A_YR			0x16
 #define RV3029_ALARM_SECTION_LEN	0x07

 /* timer section */
 #define RV3029_TIMER_LOW		0x18
 #define RV3029_TIMER_HIGH		0x19

 /* temperature section */
 #define RV3029_TEMP_PAGE		0x20

 /* eeprom data section */
 #define RV3029_E2P_EEDATA1		0x28
 #define RV3029_E2P_EEDATA2		0x29
 #define RV3029_E2PDATA_SECTION_LEN	0x02

 /* eeprom control section */
 #define RV3029_CONTROL_E2P_EECTRL	0x30
 #define RV3029_EECTRL_THP		BIT(0) /* temp scan interval */
 #define RV3029_EECTRL_THE		BIT(1) /* thermometer enable */
 #define RV3029_EECTRL_FD0		BIT(2) /* CLKOUT */
 #define RV3029_EECTRL_FD1		BIT(3) /* CLKOUT */
 #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
 #define RV3029_CONTROL_E2P_XOFFS	0x31 /* XTAL offset */
 #define RV3029_CONTROL_E2P_XOFFS_SIGN	BIT(7) /* Sign: 1->pos, 0->neg */
 #define RV3029_CONTROL_E2P_QCOEF	0x32 /* XTAL temp drift coef */
 #define RV3029_CONTROL_E2P_TURNOVER	0x33 /* XTAL turnover temp (in *C) */
 #define RV3029_CONTROL_E2P_TOV_MASK	0x3F /* XTAL turnover temp mask */

 /* user ram section */
 #define RV3029_USR1_RAM_PAGE		0x38
 #define RV3029_USR1_SECTION_LEN		0x04
 #define RV3029_USR2_RAM_PAGE		0x3C
 #define RV3029_USR2_SECTION_LEN		0x04

 static int
 rv3029_i2c_read_regs(struct i2c_client *client, u8 reg, u8 *buf,
 		     unsigned len)
 {
 	int ret;

 	if ((reg > RV3029_USR1_RAM_PAGE + 7) ||
 		(reg + len > RV3029_USR1_RAM_PAGE + 8))
 		return -EINVAL;

 	ret = i2c_smbus_read_i2c_block_data(client, reg, len, buf);
 	if (ret < 0)
 		return ret;
 	if (ret < len)
 		return -EIO;
 	return 0;
 }

 static int
 rv3029_i2c_write_regs(struct i2c_client *client, u8 reg, u8 const buf[],
 		      unsigned len)
 {
 	if ((reg > RV3029_USR1_RAM_PAGE + 7) ||
 		(reg + len > RV3029_USR1_RAM_PAGE + 8))
 		return -EINVAL;

 	return i2c_smbus_write_i2c_block_data(client, reg, len, buf);
 }

 static int
 rv3029_i2c_update_bits(struct i2c_client *client, u8 reg, u8 mask, u8 set)
 {
 	u8 buf;
 	int ret;

 	ret = rv3029_i2c_read_regs(client, reg, &buf, 1);
 	if (ret < 0)
 		return ret;
 	buf &= ~mask;
 	buf |= set & mask;
 	ret = rv3029_i2c_write_regs(client, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	return 0;
 }

 static int
 rv3029_i2c_get_sr(struct i2c_client *client, u8 *buf)
 {
 	int ret = rv3029_i2c_read_regs(client, RV3029_STATUS, buf, 1);

 	if (ret < 0)
 		return -EIO;
 	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
 	return 0;
 }

 static int
 rv3029_i2c_set_sr(struct i2c_client *client, u8 val)
 {
 	u8 buf[1];
 	int sr;

 	buf[0] = val;
 	sr = rv3029_i2c_write_regs(client, RV3029_STATUS, buf, 1);
 	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
 	if (sr < 0)
 		return -EIO;
 	return 0;
 }

 static int rv3029_eeprom_busywait(struct i2c_client *client)
 {
 	int i, ret;
 	u8 sr;

 	for (i = 100; i > 0; i--) {
 		ret = rv3029_i2c_get_sr(client, &sr);
 		if (ret < 0)
 			break;
 		if (!(sr & RV3029_STATUS_EEBUSY))
 			break;
 		usleep_range(1000, 10000);
 	}
 	if (i <= 0) {
 		dev_err(&client->dev, "EEPROM busy wait timeout.\n");
 		return -ETIMEDOUT;
 	}

 	return ret;
 }

 static int rv3029_eeprom_exit(struct i2c_client *client)
 {
 	/* Re-enable eeprom refresh */
 	return rv3029_i2c_update_bits(client, RV3029_ONOFF_CTRL,
 				      RV3029_ONOFF_CTRL_EERE,
 				      RV3029_ONOFF_CTRL_EERE);
 }

 static int rv3029_eeprom_enter(struct i2c_client *client)
 {
 	int ret;
 	u8 sr;

 	/* Check whether we are in the allowed voltage range. */
 	ret = rv3029_i2c_get_sr(client, &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_i2c_set_sr(client, sr);
 		if (ret < 0)
 			return ret;
 		usleep_range(1000, 10000);
 		ret = rv3029_i2c_get_sr(client, &sr);
 		if (ret < 0)
 			return ret;
 		if (sr & (RV3029_STATUS_VLOW1 | RV3029_STATUS_VLOW2)) {
 			dev_err(&client->dev,
 				"Supply voltage is too low to safely access the EEPROM.\n");
 			return -ENODEV;
 		}
 	}

 	/* Disable eeprom refresh. */
 	ret = rv3029_i2c_update_bits(client, 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(client);
 	if (ret < 0)
 		rv3029_eeprom_exit(client);

 	return ret;
 }

 static int rv3029_eeprom_read(struct i2c_client *client, u8 reg,
 			      u8 buf[], size_t len)
 {
 	int ret, err;

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

 	ret = rv3029_i2c_read_regs(client, reg, buf, len);

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

 	return ret;
 }

 static int rv3029_eeprom_write(struct i2c_client *client, u8 reg,
 			       u8 const buf[], size_t len)
 {
 	int ret, err;
 	size_t i;
 	u8 tmp;

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

 	for (i = 0; i < len; i++, reg++) {
 		ret = rv3029_i2c_read_regs(client, reg, &tmp, 1);
 		if (ret < 0)
 			break;
 		if (tmp != buf[i]) {
 			ret = rv3029_i2c_write_regs(client, reg, &buf[i], 1);
 			if (ret < 0)
 				break;
 		}
 		ret = rv3029_eeprom_busywait(client);
 		if (ret < 0)
 			break;
 	}

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

 	return ret;
 }

 static int rv3029_eeprom_update_bits(struct i2c_client *client,
 				     u8 reg, u8 mask, u8 set)
 {
 	u8 buf;
 	int ret;

 	ret = rv3029_eeprom_read(client, reg, &buf, 1);
 	if (ret < 0)
 		return ret;
 	buf &= ~mask;
 	buf |= set & mask;
 	ret = rv3029_eeprom_write(client, reg, &buf, 1);
 	if (ret < 0)
 		return ret;

 	return 0;
 }

 static int
 rv3029_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
 {
 	u8 buf[1];
 	int ret;
 	u8 regs[RV3029_WATCH_SECTION_LEN] = { 0, };

 	ret = rv3029_i2c_get_sr(client, buf);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}

 	ret = rv3029_i2c_read_regs(client, RV3029_W_SEC, regs,
 				   RV3029_WATCH_SECTION_LEN);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading RTC section failed\n",
 			__func__);
 		return ret;
 	}

 	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;
 	tm->tm_year = bcd2bin(regs[RV3029_W_YEARS-RV3029_W_SEC]) + 100;
 	tm->tm_wday = bcd2bin(regs[RV3029_W_DAYS-RV3029_W_SEC]) - 1;

 	return 0;
 }

 static int rv3029_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	return rv3029_i2c_read_time(to_i2c_client(dev), tm);
 }

 static int
 rv3029_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
 {
 	struct rtc_time *const tm = &alarm->time;
 	int ret;
 	u8 regs[8];

 	ret = rv3029_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}

 	ret = rv3029_i2c_read_regs(client, RV3029_A_SC, regs,
 				   RV3029_ALARM_SECTION_LEN);

 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading alarm section failed\n",
 			__func__);
 		return ret;
 	}

 	tm->tm_sec = bcd2bin(regs[RV3029_A_SC-RV3029_A_SC] & 0x7f);
 	tm->tm_min = bcd2bin(regs[RV3029_A_MN-RV3029_A_SC] & 0x7f);
 	tm->tm_hour = bcd2bin(regs[RV3029_A_HR-RV3029_A_SC] & 0x3f);
 	tm->tm_mday = bcd2bin(regs[RV3029_A_DT-RV3029_A_SC] & 0x3f);
 	tm->tm_mon = bcd2bin(regs[RV3029_A_MO-RV3029_A_SC] & 0x1f) - 1;
 	tm->tm_year = bcd2bin(regs[RV3029_A_YR-RV3029_A_SC] & 0x7f) + 100;
 	tm->tm_wday = bcd2bin(regs[RV3029_A_DW-RV3029_A_SC] & 0x07) - 1;

 	return 0;
 }

 static int
 rv3029_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	return rv3029_i2c_read_alarm(to_i2c_client(dev), alarm);
 }

 static int rv3029_rtc_i2c_alarm_set_irq(struct i2c_client *client,
 					int enable)
 {
 	int ret;

 	/* enable/disable AIE irq */
 	ret = rv3029_i2c_update_bits(client, RV3029_IRQ_CTRL,
 				     RV3029_IRQ_CTRL_AIE,
 				     (enable ? RV3029_IRQ_CTRL_AIE : 0));
 	if (ret < 0) {
 		dev_err(&client->dev, "can't update INT reg\n");
 		return ret;
 	}

 	return 0;
 }

 static int rv3029_rtc_i2c_set_alarm(struct i2c_client *client,
 				    struct rtc_wkalrm *alarm)
 {
 	struct rtc_time *const tm = &alarm->time;
 	int ret;
 	u8 regs[8];

 	/*
 	 * The clock has an 8 bit wide bcd-coded register (they never learn)
 	 * for the year. tm_year is an offset from 1900 and we are interested
 	 * in the 2000-2099 range, so any value less than 100 is invalid.
 	*/
 	if (tm->tm_year < 100)
 		return -EINVAL;

 	ret = rv3029_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}
 	regs[RV3029_A_SC-RV3029_A_SC] = bin2bcd(tm->tm_sec & 0x7f);
 	regs[RV3029_A_MN-RV3029_A_SC] = bin2bcd(tm->tm_min & 0x7f);
 	regs[RV3029_A_HR-RV3029_A_SC] = bin2bcd(tm->tm_hour & 0x3f);
 	regs[RV3029_A_DT-RV3029_A_SC] = bin2bcd(tm->tm_mday & 0x3f);
 	regs[RV3029_A_MO-RV3029_A_SC] = bin2bcd((tm->tm_mon & 0x1f) - 1);
 	regs[RV3029_A_DW-RV3029_A_SC] = bin2bcd((tm->tm_wday & 7) - 1);
 	regs[RV3029_A_YR-RV3029_A_SC] = bin2bcd((tm->tm_year & 0x7f) - 100);

 	ret = rv3029_i2c_write_regs(client, RV3029_A_SC, regs,
 				    RV3029_ALARM_SECTION_LEN);
 	if (ret < 0)
 		return ret;

 	if (alarm->enabled) {
 		/* clear AF flag */
 		ret = rv3029_i2c_update_bits(client, RV3029_IRQ_FLAGS,
 					     RV3029_IRQ_FLAGS_AF, 0);
 		if (ret < 0) {
 			dev_err(&client->dev, "can't clear alarm flag\n");
 			return ret;
 		}
 		/* enable AIE irq */
 		ret = rv3029_rtc_i2c_alarm_set_irq(client, 1);
 		if (ret)
 			return ret;

 		dev_dbg(&client->dev, "alarm IRQ armed\n");
 	} else {
 		/* disable AIE irq */
 		ret = rv3029_rtc_i2c_alarm_set_irq(client, 0);
 		if (ret)
 			return ret;

 		dev_dbg(&client->dev, "alarm IRQ disabled\n");
 	}

 	return 0;
 }

 static int rv3029_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	return rv3029_rtc_i2c_set_alarm(to_i2c_client(dev), alarm);
 }

 static int
 rv3029_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)
 {
 	u8 regs[8];
 	int ret;

 	/*
 	 * The clock has an 8 bit wide bcd-coded register (they never learn)
 	 * for the year. tm_year is an offset from 1900 and we are interested
 	 * in the 2000-2099 range, so any value less than 100 is invalid.
 	*/
 	if (tm->tm_year < 100)
 		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 & 7)+1);
 	regs[RV3029_W_YEARS-RV3029_W_SEC] = bin2bcd(tm->tm_year - 100);

 	ret = rv3029_i2c_write_regs(client, RV3029_W_SEC, regs,
 				    RV3029_WATCH_SECTION_LEN);
 	if (ret < 0)
 		return ret;

 	ret = rv3029_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return ret;
 	}
 	/* clear PON bit */
 	ret = rv3029_i2c_set_sr(client, (regs[0] & ~RV3029_STATUS_PON));
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return ret;
 	}

 	return 0;
 }

 static int rv3029_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	return rv3029_i2c_set_time(to_i2c_client(dev), tm);
 }

 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,
 	},
 };

 static void rv3029_trickle_config(struct i2c_client *client)
 {
 	struct device_node *of_node = client->dev.of_node;
 	const struct rv3029_trickle_tab_elem *elem;
 	int i, err;
 	u32 ohms;
 	u8 trickle_set_bits;

 	if (!of_node)
 		return;

 	/* Configure the trickle charger. */
 	err = of_property_read_u32(of_node, "trickle-resistor-ohms", &ohms);
 	if (err) {
 		/* Disable trickle charger. */
 		trickle_set_bits = 0;
 	} else {
 		/* Enable trickle charger. */
 		for (i = 0; i < ARRAY_SIZE(rv3029_trickle_tab); i++) {
 			elem = &rv3029_trickle_tab[i];
 			if (elem->r >= ohms)
 				break;
 		}
 		trickle_set_bits = elem->conf;
 		dev_info(&client->dev,
 			 "Trickle charger enabled at %d ohms resistance.\n",
 			 elem->r);
 	}
 	err = rv3029_eeprom_update_bits(client, RV3029_CONTROL_E2P_EECTRL,
 					RV3029_TRICKLE_MASK,
 					trickle_set_bits);
 	if (err < 0) {
 		dev_err(&client->dev,
 			"Failed to update trickle charger config\n");
 	}
 }

 #ifdef CONFIG_RTC_DRV_RV3029_HWMON

 static int rv3029_read_temp(struct i2c_client *client, int *temp_mC)
 {
 	int ret;
 	u8 temp;

 	ret = rv3029_i2c_read_regs(client, RV3029_TEMP_PAGE, &temp, 1);
 	if (ret < 0)
 		return ret;

 	*temp_mC = ((int)temp - 60) * 1000;

 	return 0;
 }

 static ssize_t rv3029_hwmon_show_temp(struct device *dev,
 				      struct device_attribute *attr,
 				      char *buf)
 {
 	struct i2c_client *client = dev_get_drvdata(dev);
 	int ret, temp_mC;

 	ret = rv3029_read_temp(client, &temp_mC);
 	if (ret < 0)
 		return ret;

 	return sprintf(buf, "%d\n", temp_mC);
 }

 static ssize_t rv3029_hwmon_set_update_interval(struct device *dev,
 						struct device_attribute *attr,
 						const char *buf,
 						size_t count)
 {
 	struct i2c_client *client = dev_get_drvdata(dev);
 	unsigned long interval_ms;
 	int ret;
 	u8 th_set_bits = 0;

 	ret = kstrtoul(buf, 10, &interval_ms);
 	if (ret < 0)
 		return ret;

 	if (interval_ms != 0) {
 		th_set_bits |= RV3029_EECTRL_THE;
 		if (interval_ms >= 16000)
 			th_set_bits |= RV3029_EECTRL_THP;
 	}
 	ret = rv3029_eeprom_update_bits(client, RV3029_CONTROL_E2P_EECTRL,
 					RV3029_EECTRL_THE | RV3029_EECTRL_THP,
 					th_set_bits);
 	if (ret < 0)
 		return ret;

 	return count;
 }

 static ssize_t rv3029_hwmon_show_update_interval(struct device *dev,
 						 struct device_attribute *attr,
 						 char *buf)
 {
 	struct i2c_client *client = dev_get_drvdata(dev);
 	int ret, interval_ms;
 	u8 eectrl;

 	ret = rv3029_eeprom_read(client, RV3029_CONTROL_E2P_EECTRL,
 				 &eectrl, 1);
 	if (ret < 0)
 		return ret;

 	if (eectrl & RV3029_EECTRL_THE) {
 		if (eectrl & RV3029_EECTRL_THP)
 			interval_ms = 16000;
 		else
 			interval_ms = 1000;
 	} else {
 		interval_ms = 0;
 	}

 	return sprintf(buf, "%d\n", interval_ms);
 }

 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, rv3029_hwmon_show_temp,
 			  NULL, 0);
 static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO,
 			  rv3029_hwmon_show_update_interval,
 			  rv3029_hwmon_set_update_interval, 0);

 static struct attribute *rv3029_hwmon_attrs[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_update_interval.dev_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(rv3029_hwmon);

 static void rv3029_hwmon_register(struct i2c_client *client)
 {
 	struct device *hwmon_dev;

 	hwmon_dev = devm_hwmon_device_register_with_groups(
 		&client->dev, client->name, client, rv3029_hwmon_groups);
 	if (IS_ERR(hwmon_dev)) {
 		dev_warn(&client->dev,
 			"unable to register hwmon device %ld\n",
 			PTR_ERR(hwmon_dev));
 	}
 }

 #else /* CONFIG_RTC_DRV_RV3029_HWMON */

 static void rv3029_hwmon_register(struct i2c_client *client)
 {
 }

 #endif /* CONFIG_RTC_DRV_RV3029_HWMON */

 static const struct rtc_class_ops rv3029_rtc_ops = {
 	.read_time	= rv3029_rtc_read_time,
 	.set_time	= rv3029_rtc_set_time,
 	.read_alarm	= rv3029_rtc_read_alarm,
 	.set_alarm	= rv3029_rtc_set_alarm,
 };

 static struct i2c_device_id rv3029_id[] = {
 	{ "rv3029", 0 },
 	{ "rv3029c2", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, rv3029_id);

 static int rv3029_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct rtc_device *rtc;
 	int rc = 0;
 	u8 buf[1];

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL))
 		return -ENODEV;

 	rc = rv3029_i2c_get_sr(client, buf);
 	if (rc < 0) {
 		dev_err(&client->dev, "reading status failed\n");
 		return rc;
 	}

 	rv3029_trickle_config(client);
 	rv3029_hwmon_register(client);

 	rtc = devm_rtc_device_register(&client->dev, client->name,
 				       &rv3029_rtc_ops, THIS_MODULE);

 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	i2c_set_clientdata(client, rtc);

 	return 0;
 }

 static struct i2c_driver rv3029_driver = {
 	.driver = {
 		.name = "rtc-rv3029c2",
 	},
 	.probe		= rv3029_probe,
 	.id_table	= rv3029_id,
 };

 module_i2c_driver(rv3029_driver);

 MODULE_AUTHOR("Gregory Hermant <gregory.hermant@calao-systems.com>");
 MODULE_AUTHOR("Michael Buesch <m@bues.ch>");
 MODULE_DESCRIPTION("Micro Crystal RV3029 RTC driver");
 MODULE_LICENSE("GPL");
	/*
	* Micro Crystal RV-3029 rtc class driver
	*
	* Author: Gregory Hermant <gregory.hermant@calao-systems.com>
	* Michael Buesch <m@bues.ch>
	*
	* based on previously existing rtc class drivers
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/bcd.h>
	#include <linux/rtc.h>
	#include <linux/delay.h>
	#include <linux/of.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>


	/* Register map */
	/* 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
	#define RV3029_WATCH_SECTION_LEN 0x07

	/* alarm section */
	#define RV3029_A_SC 0x10
	#define RV3029_A_MN 0x11
	#define RV3029_A_HR 0x12
	#define RV3029_A_DT 0x13
	#define RV3029_A_DW 0x14
	#define RV3029_A_MO 0x15
	#define RV3029_A_YR 0x16
	#define RV3029_ALARM_SECTION_LEN 0x07

	/* timer section */
	#define RV3029_TIMER_LOW 0x18
	#define RV3029_TIMER_HIGH 0x19

	/* temperature section */
	#define RV3029_TEMP_PAGE 0x20

	/* eeprom data section */
	#define RV3029_E2P_EEDATA1 0x28
	#define RV3029_E2P_EEDATA2 0x29
	#define RV3029_E2PDATA_SECTION_LEN 0x02

	/* eeprom control section */
	#define RV3029_CONTROL_E2P_EECTRL 0x30
	#define RV3029_EECTRL_THP BIT(0) /* temp scan interval */
	#define RV3029_EECTRL_THE BIT(1) /* thermometer enable */
	#define RV3029_EECTRL_FD0 BIT(2) /* CLKOUT */
	#define RV3029_EECTRL_FD1 BIT(3) /* CLKOUT */
	#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
	#define RV3029_CONTROL_E2P_XOFFS 0x31 /* XTAL offset */
	#define RV3029_CONTROL_E2P_XOFFS_SIGN BIT(7) /* Sign: 1->pos, 0->neg */
	#define RV3029_CONTROL_E2P_QCOEF 0x32 /* XTAL temp drift coef */
	#define RV3029_CONTROL_E2P_TURNOVER 0x33 /* XTAL turnover temp (in C) /
	#define RV3029_CONTROL_E2P_TOV_MASK 0x3F /* XTAL turnover temp mask */

	/* user ram section */
	#define RV3029_USR1_RAM_PAGE 0x38
	#define RV3029_USR1_SECTION_LEN 0x04
	#define RV3029_USR2_RAM_PAGE 0x3C
	#define RV3029_USR2_SECTION_LEN 0x04

	static int
	rv3029_i2c_read_regs(struct i2c_client client, u8 reg, u8 buf,
	unsigned len)
	{
	int ret;

	if ((reg > RV3029_USR1_RAM_PAGE + 7) \|\|
	(reg + len > RV3029_USR1_RAM_PAGE + 8))
	return -EINVAL;

	ret = i2c_smbus_read_i2c_block_data(client, reg, len, buf);
	if (ret < 0)
	return ret;
	if (ret < len)
	return -EIO;
	return 0;
	}

	static int
	rv3029_i2c_write_regs(struct i2c_client *client, u8 reg, u8 const buf[],
	unsigned len)
	{
	if ((reg > RV3029_USR1_RAM_PAGE + 7) \|\|
	(reg + len > RV3029_USR1_RAM_PAGE + 8))
	return -EINVAL;

	return i2c_smbus_write_i2c_block_data(client, reg, len, buf);
	}

	static int
	rv3029_i2c_update_bits(struct i2c_client *client, u8 reg, u8 mask, u8 set)
	{
	u8 buf;
	int ret;

	ret = rv3029_i2c_read_regs(client, reg, &buf, 1);
	if (ret < 0)
	return ret;
	buf &= ~mask;
	buf \|= set & mask;
	ret = rv3029_i2c_write_regs(client, reg, &buf, 1);
	if (ret < 0)
	return ret;

	return 0;
	}

	static int
	rv3029_i2c_get_sr(struct i2c_client client, u8 buf)
	{
	int ret = rv3029_i2c_read_regs(client, RV3029_STATUS, buf, 1);

	if (ret < 0)
	return -EIO;
	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
	return 0;
	}

	static int
	rv3029_i2c_set_sr(struct i2c_client *client, u8 val)
	{
	u8 buf[1];
	int sr;

	buf[0] = val;
	sr = rv3029_i2c_write_regs(client, RV3029_STATUS, buf, 1);
	dev_dbg(&client->dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
	if (sr < 0)
	return -EIO;
	return 0;
	}

	static int rv3029_eeprom_busywait(struct i2c_client *client)
	{
	int i, ret;
	u8 sr;

	for (i = 100; i > 0; i--) {
	ret = rv3029_i2c_get_sr(client, &sr);
	if (ret < 0)
	break;
	if (!(sr & RV3029_STATUS_EEBUSY))
	break;
	usleep_range(1000, 10000);
	}
	if (i <= 0) {
	dev_err(&client->dev, "EEPROM busy wait timeout.\n");
	return -ETIMEDOUT;
	}

	return ret;
	}

	static int rv3029_eeprom_exit(struct i2c_client *client)
	{
	/* Re-enable eeprom refresh */
	return rv3029_i2c_update_bits(client, RV3029_ONOFF_CTRL,
	RV3029_ONOFF_CTRL_EERE,
	RV3029_ONOFF_CTRL_EERE);
	}

	static int rv3029_eeprom_enter(struct i2c_client *client)
	{
	int ret;
	u8 sr;

	/* Check whether we are in the allowed voltage range. */
	ret = rv3029_i2c_get_sr(client, &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_i2c_set_sr(client, sr);
	if (ret < 0)
	return ret;
	usleep_range(1000, 10000);
	ret = rv3029_i2c_get_sr(client, &sr);
	if (ret < 0)
	return ret;
	if (sr & (RV3029_STATUS_VLOW1 \| RV3029_STATUS_VLOW2)) {
	dev_err(&client->dev,
	"Supply voltage is too low to safely access the EEPROM.\n");
	return -ENODEV;
	}
	}

	/* Disable eeprom refresh. */
	ret = rv3029_i2c_update_bits(client, 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(client);
	if (ret < 0)
	rv3029_eeprom_exit(client);

	return ret;
	}

	static int rv3029_eeprom_read(struct i2c_client *client, u8 reg,
	u8 buf[], size_t len)
	{
	int ret, err;

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

	ret = rv3029_i2c_read_regs(client, reg, buf, len);

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

	return ret;
	}

	static int rv3029_eeprom_write(struct i2c_client *client, u8 reg,
	u8 const buf[], size_t len)
	{
	int ret, err;
	size_t i;
	u8 tmp;

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

	for (i = 0; i < len; i++, reg++) {
	ret = rv3029_i2c_read_regs(client, reg, &tmp, 1);
	if (ret < 0)
	break;
	if (tmp != buf[i]) {
	ret = rv3029_i2c_write_regs(client, reg, &buf[i], 1);
	if (ret < 0)
	break;
	}
	ret = rv3029_eeprom_busywait(client);
	if (ret < 0)
	break;
	}

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

	return ret;
	}

	static int rv3029_eeprom_update_bits(struct i2c_client *client,
	u8 reg, u8 mask, u8 set)
	{
	u8 buf;
	int ret;

	ret = rv3029_eeprom_read(client, reg, &buf, 1);
	if (ret < 0)
	return ret;
	buf &= ~mask;
	buf \|= set & mask;
	ret = rv3029_eeprom_write(client, reg, &buf, 1);
	if (ret < 0)
	return ret;

	return 0;
	}

	static int
	rv3029_i2c_read_time(struct i2c_client client, struct rtc_time tm)
	{
	u8 buf[1];
	int ret;
	u8 regs[RV3029_WATCH_SECTION_LEN] = { 0, };

	ret = rv3029_i2c_get_sr(client, buf);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}

	ret = rv3029_i2c_read_regs(client, RV3029_W_SEC, regs,
	RV3029_WATCH_SECTION_LEN);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading RTC section failed\n",
	__func__);
	return ret;
	}

	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;
	tm->tm_year = bcd2bin(regs[RV3029_W_YEARS-RV3029_W_SEC]) + 100;
	tm->tm_wday = bcd2bin(regs[RV3029_W_DAYS-RV3029_W_SEC]) - 1;

	return 0;
	}

	static int rv3029_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	return rv3029_i2c_read_time(to_i2c_client(dev), tm);
	}

	static int
	rv3029_i2c_read_alarm(struct i2c_client client, struct rtc_wkalrm alarm)
	{
	struct rtc_time *const tm = &alarm->time;
	int ret;
	u8 regs[8];

	ret = rv3029_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}

	ret = rv3029_i2c_read_regs(client, RV3029_A_SC, regs,
	RV3029_ALARM_SECTION_LEN);

	if (ret < 0) {
	dev_err(&client->dev, "%s: reading alarm section failed\n",
	__func__);
	return ret;
	}

	tm->tm_sec = bcd2bin(regs[RV3029_A_SC-RV3029_A_SC] & 0x7f);
	tm->tm_min = bcd2bin(regs[RV3029_A_MN-RV3029_A_SC] & 0x7f);
	tm->tm_hour = bcd2bin(regs[RV3029_A_HR-RV3029_A_SC] & 0x3f);
	tm->tm_mday = bcd2bin(regs[RV3029_A_DT-RV3029_A_SC] & 0x3f);
	tm->tm_mon = bcd2bin(regs[RV3029_A_MO-RV3029_A_SC] & 0x1f) - 1;
	tm->tm_year = bcd2bin(regs[RV3029_A_YR-RV3029_A_SC] & 0x7f) + 100;
	tm->tm_wday = bcd2bin(regs[RV3029_A_DW-RV3029_A_SC] & 0x07) - 1;

	return 0;
	}

	static int
	rv3029_rtc_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	return rv3029_i2c_read_alarm(to_i2c_client(dev), alarm);
	}

	static int rv3029_rtc_i2c_alarm_set_irq(struct i2c_client *client,
	int enable)
	{
	int ret;

	/* enable/disable AIE irq */
	ret = rv3029_i2c_update_bits(client, RV3029_IRQ_CTRL,
	RV3029_IRQ_CTRL_AIE,
	(enable ? RV3029_IRQ_CTRL_AIE : 0));
	if (ret < 0) {
	dev_err(&client->dev, "can't update INT reg\n");
	return ret;
	}

	return 0;
	}

	static int rv3029_rtc_i2c_set_alarm(struct i2c_client *client,
	struct rtc_wkalrm *alarm)
	{
	struct rtc_time *const tm = &alarm->time;
	int ret;
	u8 regs[8];

	/*
	* The clock has an 8 bit wide bcd-coded register (they never learn)
	* for the year. tm_year is an offset from 1900 and we are interested
	* in the 2000-2099 range, so any value less than 100 is invalid.
	*/
	if (tm->tm_year < 100)
	return -EINVAL;

	ret = rv3029_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}
	regs[RV3029_A_SC-RV3029_A_SC] = bin2bcd(tm->tm_sec & 0x7f);
	regs[RV3029_A_MN-RV3029_A_SC] = bin2bcd(tm->tm_min & 0x7f);
	regs[RV3029_A_HR-RV3029_A_SC] = bin2bcd(tm->tm_hour & 0x3f);
	regs[RV3029_A_DT-RV3029_A_SC] = bin2bcd(tm->tm_mday & 0x3f);
	regs[RV3029_A_MO-RV3029_A_SC] = bin2bcd((tm->tm_mon & 0x1f) - 1);
	regs[RV3029_A_DW-RV3029_A_SC] = bin2bcd((tm->tm_wday & 7) - 1);
	regs[RV3029_A_YR-RV3029_A_SC] = bin2bcd((tm->tm_year & 0x7f) - 100);

	ret = rv3029_i2c_write_regs(client, RV3029_A_SC, regs,
	RV3029_ALARM_SECTION_LEN);
	if (ret < 0)
	return ret;

	if (alarm->enabled) {
	/* clear AF flag */
	ret = rv3029_i2c_update_bits(client, RV3029_IRQ_FLAGS,
	RV3029_IRQ_FLAGS_AF, 0);
	if (ret < 0) {
	dev_err(&client->dev, "can't clear alarm flag\n");
	return ret;
	}
	/* enable AIE irq */
	ret = rv3029_rtc_i2c_alarm_set_irq(client, 1);
	if (ret)
	return ret;

	dev_dbg(&client->dev, "alarm IRQ armed\n");
	} else {
	/* disable AIE irq */
	ret = rv3029_rtc_i2c_alarm_set_irq(client, 0);
	if (ret)
	return ret;

	dev_dbg(&client->dev, "alarm IRQ disabled\n");
	}

	return 0;
	}

	static int rv3029_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	return rv3029_rtc_i2c_set_alarm(to_i2c_client(dev), alarm);
	}

	static int
	rv3029_i2c_set_time(struct i2c_client client, struct rtc_time const tm)
	{
	u8 regs[8];
	int ret;

	/*
	* The clock has an 8 bit wide bcd-coded register (they never learn)
	* for the year. tm_year is an offset from 1900 and we are interested
	* in the 2000-2099 range, so any value less than 100 is invalid.
	*/
	if (tm->tm_year < 100)
	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 & 7)+1);
	regs[RV3029_W_YEARS-RV3029_W_SEC] = bin2bcd(tm->tm_year - 100);

	ret = rv3029_i2c_write_regs(client, RV3029_W_SEC, regs,
	RV3029_WATCH_SECTION_LEN);
	if (ret < 0)
	return ret;

	ret = rv3029_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return ret;
	}
	/* clear PON bit */
	ret = rv3029_i2c_set_sr(client, (regs[0] & ~RV3029_STATUS_PON));
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return ret;
	}

	return 0;
	}

	static int rv3029_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	return rv3029_i2c_set_time(to_i2c_client(dev), tm);
	}

	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,
	},
	};

	static void rv3029_trickle_config(struct i2c_client *client)
	{
	struct device_node *of_node = client->dev.of_node;
	const struct rv3029_trickle_tab_elem *elem;
	int i, err;
	u32 ohms;
	u8 trickle_set_bits;

	if (!of_node)
	return;

	/* Configure the trickle charger. */
	err = of_property_read_u32(of_node, "trickle-resistor-ohms", &ohms);
	if (err) {
	/* Disable trickle charger. */
	trickle_set_bits = 0;
	} else {
	/* Enable trickle charger. */
	for (i = 0; i < ARRAY_SIZE(rv3029_trickle_tab); i++) {
	elem = &rv3029_trickle_tab[i];
	if (elem->r >= ohms)
	break;
	}
	trickle_set_bits = elem->conf;
	dev_info(&client->dev,
	"Trickle charger enabled at %d ohms resistance.\n",
	elem->r);
	}
	err = rv3029_eeprom_update_bits(client, RV3029_CONTROL_E2P_EECTRL,
	RV3029_TRICKLE_MASK,
	trickle_set_bits);
	if (err < 0) {
	dev_err(&client->dev,
	"Failed to update trickle charger config\n");
	}
	}

	#ifdef CONFIG_RTC_DRV_RV3029_HWMON

	static int rv3029_read_temp(struct i2c_client client, int temp_mC)
	{
	int ret;
	u8 temp;

	ret = rv3029_i2c_read_regs(client, RV3029_TEMP_PAGE, &temp, 1);
	if (ret < 0)
	return ret;

	temp_mC = ((int)temp - 60) 1000;

	return 0;
	}

	static ssize_t rv3029_hwmon_show_temp(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct i2c_client *client = dev_get_drvdata(dev);
	int ret, temp_mC;

	ret = rv3029_read_temp(client, &temp_mC);
	if (ret < 0)
	return ret;

	return sprintf(buf, "%d\n", temp_mC);
	}

	static ssize_t rv3029_hwmon_set_update_interval(struct device *dev,
	struct device_attribute *attr,
	const char *buf,
	size_t count)
	{
	struct i2c_client *client = dev_get_drvdata(dev);
	unsigned long interval_ms;
	int ret;
	u8 th_set_bits = 0;

	ret = kstrtoul(buf, 10, &interval_ms);
	if (ret < 0)
	return ret;

	if (interval_ms != 0) {
	th_set_bits \|= RV3029_EECTRL_THE;
	if (interval_ms >= 16000)
	th_set_bits \|= RV3029_EECTRL_THP;
	}
	ret = rv3029_eeprom_update_bits(client, RV3029_CONTROL_E2P_EECTRL,
	RV3029_EECTRL_THE \| RV3029_EECTRL_THP,
	th_set_bits);
	if (ret < 0)
	return ret;

	return count;
	}

	static ssize_t rv3029_hwmon_show_update_interval(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct i2c_client *client = dev_get_drvdata(dev);
	int ret, interval_ms;
	u8 eectrl;

	ret = rv3029_eeprom_read(client, RV3029_CONTROL_E2P_EECTRL,
	&eectrl, 1);
	if (ret < 0)
	return ret;

	if (eectrl & RV3029_EECTRL_THE) {
	if (eectrl & RV3029_EECTRL_THP)
	interval_ms = 16000;
	else
	interval_ms = 1000;
	} else {
	interval_ms = 0;
	}

	return sprintf(buf, "%d\n", interval_ms);
	}

	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, rv3029_hwmon_show_temp,
	NULL, 0);
	static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR \| S_IRUGO,
	rv3029_hwmon_show_update_interval,
	rv3029_hwmon_set_update_interval, 0);

	static struct attribute *rv3029_hwmon_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_update_interval.dev_attr.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(rv3029_hwmon);

	static void rv3029_hwmon_register(struct i2c_client *client)
	{
	struct device *hwmon_dev;

	hwmon_dev = devm_hwmon_device_register_with_groups(
	&client->dev, client->name, client, rv3029_hwmon_groups);
	if (IS_ERR(hwmon_dev)) {
	dev_warn(&client->dev,
	"unable to register hwmon device %ld\n",
	PTR_ERR(hwmon_dev));
	}
	}

	#else /* CONFIG_RTC_DRV_RV3029_HWMON */

	static void rv3029_hwmon_register(struct i2c_client *client)
	{
	}

	#endif /* CONFIG_RTC_DRV_RV3029_HWMON */

	static const struct rtc_class_ops rv3029_rtc_ops = {
	.read_time = rv3029_rtc_read_time,
	.set_time = rv3029_rtc_set_time,
	.read_alarm = rv3029_rtc_read_alarm,
	.set_alarm = rv3029_rtc_set_alarm,
	};

	static struct i2c_device_id rv3029_id[] = {
	{ "rv3029", 0 },
	{ "rv3029c2", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, rv3029_id);

	static int rv3029_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct rtc_device *rtc;
	int rc = 0;
	u8 buf[1];

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL))
	return -ENODEV;

	rc = rv3029_i2c_get_sr(client, buf);
	if (rc < 0) {
	dev_err(&client->dev, "reading status failed\n");
	return rc;
	}

	rv3029_trickle_config(client);
	rv3029_hwmon_register(client);

	rtc = devm_rtc_device_register(&client->dev, client->name,
	&rv3029_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	i2c_set_clientdata(client, rtc);

	return 0;
	}

	static struct i2c_driver rv3029_driver = {
	.driver = {
	.name = "rtc-rv3029c2",
	},
	.probe = rv3029_probe,
	.id_table = rv3029_id,
	};

	module_i2c_driver(rv3029_driver);

	MODULE_AUTHOR("Gregory Hermant <gregory.hermant@calao-systems.com>");
	MODULE_AUTHOR("Michael Buesch <m@bues.ch>");
	MODULE_DESCRIPTION("Micro Crystal RV3029 RTC driver");
	MODULE_LICENSE("GPL");