drivers/rtc/rtc-rv3029c2.c - linux - Git at Google

 /*
  * Micro Crystal RV-3029C2 rtc class driver
  *
  * Author: Gregory Hermant <gregory.hermant@calao-systems.com>
  *
  * 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.
  *
  * NOTE: Currently this driver only supports the bare minimum for read
  * and write the RTC and alarms. The extra features provided by this chip
  * (trickle charger, eeprom, T° compensation) are unavailable.
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/bcd.h>
 #include <linux/rtc.h>

 /* Register map */
 /* control section */
 #define RV3029C2_ONOFF_CTRL		0x00
 #define RV3029C2_IRQ_CTRL		0x01
 #define RV3029C2_IRQ_CTRL_AIE		(1 << 0)
 #define RV3029C2_IRQ_FLAGS		0x02
 #define RV3029C2_IRQ_FLAGS_AF		(1 << 0)
 #define RV3029C2_STATUS			0x03
 #define RV3029C2_STATUS_VLOW1		(1 << 2)
 #define RV3029C2_STATUS_VLOW2		(1 << 3)
 #define RV3029C2_STATUS_SR		(1 << 4)
 #define RV3029C2_STATUS_PON		(1 << 5)
 #define RV3029C2_STATUS_EEBUSY		(1 << 7)
 #define RV3029C2_RST_CTRL		0x04
 #define RV3029C2_CONTROL_SECTION_LEN	0x05

 /* watch section */
 #define RV3029C2_W_SEC			0x08
 #define RV3029C2_W_MINUTES		0x09
 #define RV3029C2_W_HOURS		0x0A
 #define RV3029C2_REG_HR_12_24		(1<<6)  /* 24h/12h mode */
 #define RV3029C2_REG_HR_PM		(1<<5)  /* PM/AM bit in 12h mode */
 #define RV3029C2_W_DATE			0x0B
 #define RV3029C2_W_DAYS			0x0C
 #define RV3029C2_W_MONTHS		0x0D
 #define RV3029C2_W_YEARS		0x0E
 #define RV3029C2_WATCH_SECTION_LEN	0x07

 /* alarm section */
 #define RV3029C2_A_SC			0x10
 #define RV3029C2_A_MN			0x11
 #define RV3029C2_A_HR			0x12
 #define RV3029C2_A_DT			0x13
 #define RV3029C2_A_DW			0x14
 #define RV3029C2_A_MO			0x15
 #define RV3029C2_A_YR			0x16
 #define RV3029C2_ALARM_SECTION_LEN	0x07

 /* timer section */
 #define RV3029C2_TIMER_LOW		0x18
 #define RV3029C2_TIMER_HIGH		0x19

 /* temperature section */
 #define RV3029C2_TEMP_PAGE		0x20

 /* eeprom data section */
 #define RV3029C2_E2P_EEDATA1		0x28
 #define RV3029C2_E2P_EEDATA2		0x29

 /* eeprom control section */
 #define RV3029C2_CONTROL_E2P_EECTRL	0x30
 #define RV3029C2_TRICKLE_1K		(1<<0)  /*  1K resistance */
 #define RV3029C2_TRICKLE_5K		(1<<1)  /*  5K resistance */
 #define RV3029C2_TRICKLE_20K		(1<<2)  /* 20K resistance */
 #define RV3029C2_TRICKLE_80K		(1<<3)  /* 80K resistance */
 #define RV3029C2_CONTROL_E2P_XTALOFFSET	0x31
 #define RV3029C2_CONTROL_E2P_QCOEF	0x32
 #define RV3029C2_CONTROL_E2P_TURNOVER	0x33

 /* user ram section */
 #define RV3029C2_USR1_RAM_PAGE		0x38
 #define RV3029C2_USR1_SECTION_LEN	0x04
 #define RV3029C2_USR2_RAM_PAGE		0x3C
 #define RV3029C2_USR2_SECTION_LEN	0x04

 static int
 rv3029c2_i2c_read_regs(struct i2c_client *client, u8 reg, u8 *buf,
 	unsigned len)
 {
 	int ret;

 	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) ||
 		(reg + len > RV3029C2_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
 rv3029c2_i2c_write_regs(struct i2c_client *client, u8 reg, u8 const buf[],
 			unsigned len)
 {
 	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) ||
 		(reg + len > RV3029C2_USR1_RAM_PAGE + 8))
 		return -EINVAL;

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

 static int
 rv3029c2_i2c_get_sr(struct i2c_client *client, u8 *buf)
 {
 	int ret = rv3029c2_i2c_read_regs(client, RV3029C2_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
 rv3029c2_i2c_set_sr(struct i2c_client *client, u8 val)
 {
 	u8 buf[1];
 	int sr;

 	buf[0] = val;
 	sr = rv3029c2_i2c_write_regs(client, RV3029C2_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
 rv3029c2_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
 {
 	u8 buf[1];
 	int ret;
 	u8 regs[RV3029C2_WATCH_SECTION_LEN] = { 0, };

 	ret = rv3029c2_i2c_get_sr(client, buf);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}

 	ret = rv3029c2_i2c_read_regs(client, RV3029C2_W_SEC , regs,
 					RV3029C2_WATCH_SECTION_LEN);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading RTC section failed\n",
 			__func__);
 		return ret;
 	}

 	tm->tm_sec = bcd2bin(regs[RV3029C2_W_SEC-RV3029C2_W_SEC]);
 	tm->tm_min = bcd2bin(regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC]);

 	/* HR field has a more complex interpretation */
 	{
 		const u8 _hr = regs[RV3029C2_W_HOURS-RV3029C2_W_SEC];
 		if (_hr & RV3029C2_REG_HR_12_24) {
 			/* 12h format */
 			tm->tm_hour = bcd2bin(_hr & 0x1f);
 			if (_hr & RV3029C2_REG_HR_PM)	/* PM flag set */
 				tm->tm_hour += 12;
 		} else /* 24h format */
 			tm->tm_hour = bcd2bin(_hr & 0x3f);
 	}

 	tm->tm_mday = bcd2bin(regs[RV3029C2_W_DATE-RV3029C2_W_SEC]);
 	tm->tm_mon = bcd2bin(regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC]) - 1;
 	tm->tm_year = bcd2bin(regs[RV3029C2_W_YEARS-RV3029C2_W_SEC]) + 100;
 	tm->tm_wday = bcd2bin(regs[RV3029C2_W_DAYS-RV3029C2_W_SEC]) - 1;

 	return 0;
 }

 static int rv3029c2_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	return rv3029c2_i2c_read_time(to_i2c_client(dev), tm);
 }

 static int
 rv3029c2_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
 {
 	struct rtc_time *const tm = &alarm->time;
 	int ret;
 	u8 regs[8];

 	ret = rv3029c2_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}

 	ret = rv3029c2_i2c_read_regs(client, RV3029C2_A_SC, regs,
 					RV3029C2_ALARM_SECTION_LEN);

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

 	tm->tm_sec = bcd2bin(regs[RV3029C2_A_SC-RV3029C2_A_SC] & 0x7f);
 	tm->tm_min = bcd2bin(regs[RV3029C2_A_MN-RV3029C2_A_SC] & 0x7f);
 	tm->tm_hour = bcd2bin(regs[RV3029C2_A_HR-RV3029C2_A_SC] & 0x3f);
 	tm->tm_mday = bcd2bin(regs[RV3029C2_A_DT-RV3029C2_A_SC] & 0x3f);
 	tm->tm_mon = bcd2bin(regs[RV3029C2_A_MO-RV3029C2_A_SC] & 0x1f) - 1;
 	tm->tm_year = bcd2bin(regs[RV3029C2_A_YR-RV3029C2_A_SC] & 0x7f) + 100;
 	tm->tm_wday = bcd2bin(regs[RV3029C2_A_DW-RV3029C2_A_SC] & 0x07) - 1;

 	return 0;
 }

 static int
 rv3029c2_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	return rv3029c2_i2c_read_alarm(to_i2c_client(dev), alarm);
 }

 static int rv3029c2_rtc_i2c_alarm_set_irq(struct i2c_client *client,
 					int enable)
 {
 	int ret;
 	u8 buf[1];

 	/* enable AIE irq */
 	ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_CTRL,	buf, 1);
 	if (ret < 0) {
 		dev_err(&client->dev, "can't read INT reg\n");
 		return ret;
 	}
 	if (enable)
 		buf[0] |= RV3029C2_IRQ_CTRL_AIE;
 	else
 		buf[0] &= ~RV3029C2_IRQ_CTRL_AIE;

 	ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_CTRL, buf, 1);
 	if (ret < 0) {
 		dev_err(&client->dev, "can't set INT reg\n");
 		return ret;
 	}

 	return 0;
 }

 static int rv3029c2_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 = rv3029c2_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return -EIO;
 	}
 	regs[RV3029C2_A_SC-RV3029C2_A_SC] = bin2bcd(tm->tm_sec & 0x7f);
 	regs[RV3029C2_A_MN-RV3029C2_A_SC] = bin2bcd(tm->tm_min & 0x7f);
 	regs[RV3029C2_A_HR-RV3029C2_A_SC] = bin2bcd(tm->tm_hour & 0x3f);
 	regs[RV3029C2_A_DT-RV3029C2_A_SC] = bin2bcd(tm->tm_mday & 0x3f);
 	regs[RV3029C2_A_MO-RV3029C2_A_SC] = bin2bcd((tm->tm_mon & 0x1f) - 1);
 	regs[RV3029C2_A_DW-RV3029C2_A_SC] = bin2bcd((tm->tm_wday & 7) - 1);
 	regs[RV3029C2_A_YR-RV3029C2_A_SC] = bin2bcd((tm->tm_year & 0x7f) - 100);

 	ret = rv3029c2_i2c_write_regs(client, RV3029C2_A_SC, regs,
 					RV3029C2_ALARM_SECTION_LEN);
 	if (ret < 0)
 		return ret;

 	if (alarm->enabled) {
 		u8 buf[1];

 		/* clear AF flag */
 		ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_FLAGS,
 						buf, 1);
 		if (ret < 0) {
 			dev_err(&client->dev, "can't read alarm flag\n");
 			return ret;
 		}
 		buf[0] &= ~RV3029C2_IRQ_FLAGS_AF;
 		ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_FLAGS,
 						buf, 1);
 		if (ret < 0) {
 			dev_err(&client->dev, "can't set alarm flag\n");
 			return ret;
 		}
 		/* enable AIE irq */
 		ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 1);
 		if (ret)
 			return ret;

 		dev_dbg(&client->dev, "alarm IRQ armed\n");
 	} else {
 		/* disable AIE irq */
 		ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 0);
 		if (ret)
 			return ret;

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

 	return 0;
 }

 static int rv3029c2_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	return rv3029c2_rtc_i2c_set_alarm(to_i2c_client(dev), alarm);
 }

 static int
 rv3029c2_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[RV3029C2_W_SEC-RV3029C2_W_SEC] = bin2bcd(tm->tm_sec);
 	regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC] = bin2bcd(tm->tm_min);
 	regs[RV3029C2_W_HOURS-RV3029C2_W_SEC] = bin2bcd(tm->tm_hour);
 	regs[RV3029C2_W_DATE-RV3029C2_W_SEC] = bin2bcd(tm->tm_mday);
 	regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC] = bin2bcd(tm->tm_mon+1);
 	regs[RV3029C2_W_DAYS-RV3029C2_W_SEC] = bin2bcd((tm->tm_wday & 7)+1);
 	regs[RV3029C2_W_YEARS-RV3029C2_W_SEC] = bin2bcd(tm->tm_year - 100);

 	ret = rv3029c2_i2c_write_regs(client, RV3029C2_W_SEC, regs,
 					RV3029C2_WATCH_SECTION_LEN);
 	if (ret < 0)
 		return ret;

 	ret = rv3029c2_i2c_get_sr(client, regs);
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return ret;
 	}
 	/* clear PON bit */
 	ret = rv3029c2_i2c_set_sr(client, (regs[0] & ~RV3029C2_STATUS_PON));
 	if (ret < 0) {
 		dev_err(&client->dev, "%s: reading SR failed\n", __func__);
 		return ret;
 	}

 	return 0;
 }

 static int rv3029c2_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	return rv3029c2_i2c_set_time(to_i2c_client(dev), tm);
 }

 static const struct rtc_class_ops rv3029c2_rtc_ops = {
 	.read_time	= rv3029c2_rtc_read_time,
 	.set_time	= rv3029c2_rtc_set_time,
 	.read_alarm	= rv3029c2_rtc_read_alarm,
 	.set_alarm	= rv3029c2_rtc_set_alarm,
 };

 static struct i2c_device_id rv3029c2_id[] = {
 	{ "rv3029c2", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, rv3029c2_id);

 static int rv3029c2_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;

 	rtc = devm_rtc_device_register(&client->dev, client->name,
 					&rv3029c2_rtc_ops, THIS_MODULE);

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

 	i2c_set_clientdata(client, rtc);

 	rc = rv3029c2_i2c_get_sr(client, buf);
 	if (rc < 0) {
 		dev_err(&client->dev, "reading status failed\n");
 		return rc;
 	}

 	return 0;
 }

 static struct i2c_driver rv3029c2_driver = {
 	.driver = {
 		.name = "rtc-rv3029c2",
 	},
 	.probe = rv3029c2_probe,
 	.id_table = rv3029c2_id,
 };

 module_i2c_driver(rv3029c2_driver);

 MODULE_AUTHOR("Gregory Hermant <gregory.hermant@calao-systems.com>");
 MODULE_DESCRIPTION("Micro Crystal RV3029C2 RTC driver");
 MODULE_LICENSE("GPL");
	/*
	* Micro Crystal RV-3029C2 rtc class driver
	*
	* Author: Gregory Hermant <gregory.hermant@calao-systems.com>
	*
	* 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.
	*
	* NOTE: Currently this driver only supports the bare minimum for read
	* and write the RTC and alarms. The extra features provided by this chip
	* (trickle charger, eeprom, T° compensation) are unavailable.
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/bcd.h>
	#include <linux/rtc.h>

	/* Register map */
	/* control section */
	#define RV3029C2_ONOFF_CTRL 0x00
	#define RV3029C2_IRQ_CTRL 0x01
	#define RV3029C2_IRQ_CTRL_AIE (1 << 0)
	#define RV3029C2_IRQ_FLAGS 0x02
	#define RV3029C2_IRQ_FLAGS_AF (1 << 0)
	#define RV3029C2_STATUS 0x03
	#define RV3029C2_STATUS_VLOW1 (1 << 2)
	#define RV3029C2_STATUS_VLOW2 (1 << 3)
	#define RV3029C2_STATUS_SR (1 << 4)
	#define RV3029C2_STATUS_PON (1 << 5)
	#define RV3029C2_STATUS_EEBUSY (1 << 7)
	#define RV3029C2_RST_CTRL 0x04
	#define RV3029C2_CONTROL_SECTION_LEN 0x05

	/* watch section */
	#define RV3029C2_W_SEC 0x08
	#define RV3029C2_W_MINUTES 0x09
	#define RV3029C2_W_HOURS 0x0A
	#define RV3029C2_REG_HR_12_24 (1<<6) /* 24h/12h mode */
	#define RV3029C2_REG_HR_PM (1<<5) /* PM/AM bit in 12h mode */
	#define RV3029C2_W_DATE 0x0B
	#define RV3029C2_W_DAYS 0x0C
	#define RV3029C2_W_MONTHS 0x0D
	#define RV3029C2_W_YEARS 0x0E
	#define RV3029C2_WATCH_SECTION_LEN 0x07

	/* alarm section */
	#define RV3029C2_A_SC 0x10
	#define RV3029C2_A_MN 0x11
	#define RV3029C2_A_HR 0x12
	#define RV3029C2_A_DT 0x13
	#define RV3029C2_A_DW 0x14
	#define RV3029C2_A_MO 0x15
	#define RV3029C2_A_YR 0x16
	#define RV3029C2_ALARM_SECTION_LEN 0x07

	/* timer section */
	#define RV3029C2_TIMER_LOW 0x18
	#define RV3029C2_TIMER_HIGH 0x19

	/* temperature section */
	#define RV3029C2_TEMP_PAGE 0x20

	/* eeprom data section */
	#define RV3029C2_E2P_EEDATA1 0x28
	#define RV3029C2_E2P_EEDATA2 0x29

	/* eeprom control section */
	#define RV3029C2_CONTROL_E2P_EECTRL 0x30
	#define RV3029C2_TRICKLE_1K (1<<0) /* 1K resistance */
	#define RV3029C2_TRICKLE_5K (1<<1) /* 5K resistance */
	#define RV3029C2_TRICKLE_20K (1<<2) /* 20K resistance */
	#define RV3029C2_TRICKLE_80K (1<<3) /* 80K resistance */
	#define RV3029C2_CONTROL_E2P_XTALOFFSET 0x31
	#define RV3029C2_CONTROL_E2P_QCOEF 0x32
	#define RV3029C2_CONTROL_E2P_TURNOVER 0x33

	/* user ram section */
	#define RV3029C2_USR1_RAM_PAGE 0x38
	#define RV3029C2_USR1_SECTION_LEN 0x04
	#define RV3029C2_USR2_RAM_PAGE 0x3C
	#define RV3029C2_USR2_SECTION_LEN 0x04

	static int
	rv3029c2_i2c_read_regs(struct i2c_client client, u8 reg, u8 buf,
	unsigned len)
	{
	int ret;

	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) \|\|
	(reg + len > RV3029C2_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
	rv3029c2_i2c_write_regs(struct i2c_client *client, u8 reg, u8 const buf[],
	unsigned len)
	{
	if ((reg > RV3029C2_USR1_RAM_PAGE + 7) \|\|
	(reg + len > RV3029C2_USR1_RAM_PAGE + 8))
	return -EINVAL;

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

	static int
	rv3029c2_i2c_get_sr(struct i2c_client client, u8 buf)
	{
	int ret = rv3029c2_i2c_read_regs(client, RV3029C2_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
	rv3029c2_i2c_set_sr(struct i2c_client *client, u8 val)
	{
	u8 buf[1];
	int sr;

	buf[0] = val;
	sr = rv3029c2_i2c_write_regs(client, RV3029C2_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
	rv3029c2_i2c_read_time(struct i2c_client client, struct rtc_time tm)
	{
	u8 buf[1];
	int ret;
	u8 regs[RV3029C2_WATCH_SECTION_LEN] = { 0, };

	ret = rv3029c2_i2c_get_sr(client, buf);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}

	ret = rv3029c2_i2c_read_regs(client, RV3029C2_W_SEC , regs,
	RV3029C2_WATCH_SECTION_LEN);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading RTC section failed\n",
	__func__);
	return ret;
	}

	tm->tm_sec = bcd2bin(regs[RV3029C2_W_SEC-RV3029C2_W_SEC]);
	tm->tm_min = bcd2bin(regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC]);

	/* HR field has a more complex interpretation */
	{
	const u8 _hr = regs[RV3029C2_W_HOURS-RV3029C2_W_SEC];
	if (_hr & RV3029C2_REG_HR_12_24) {
	/* 12h format */
	tm->tm_hour = bcd2bin(_hr & 0x1f);
	if (_hr & RV3029C2_REG_HR_PM) /* PM flag set */
	tm->tm_hour += 12;
	} else /* 24h format */
	tm->tm_hour = bcd2bin(_hr & 0x3f);
	}

	tm->tm_mday = bcd2bin(regs[RV3029C2_W_DATE-RV3029C2_W_SEC]);
	tm->tm_mon = bcd2bin(regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC]) - 1;
	tm->tm_year = bcd2bin(regs[RV3029C2_W_YEARS-RV3029C2_W_SEC]) + 100;
	tm->tm_wday = bcd2bin(regs[RV3029C2_W_DAYS-RV3029C2_W_SEC]) - 1;

	return 0;
	}

	static int rv3029c2_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	return rv3029c2_i2c_read_time(to_i2c_client(dev), tm);
	}

	static int
	rv3029c2_i2c_read_alarm(struct i2c_client client, struct rtc_wkalrm alarm)
	{
	struct rtc_time *const tm = &alarm->time;
	int ret;
	u8 regs[8];

	ret = rv3029c2_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}

	ret = rv3029c2_i2c_read_regs(client, RV3029C2_A_SC, regs,
	RV3029C2_ALARM_SECTION_LEN);

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

	tm->tm_sec = bcd2bin(regs[RV3029C2_A_SC-RV3029C2_A_SC] & 0x7f);
	tm->tm_min = bcd2bin(regs[RV3029C2_A_MN-RV3029C2_A_SC] & 0x7f);
	tm->tm_hour = bcd2bin(regs[RV3029C2_A_HR-RV3029C2_A_SC] & 0x3f);
	tm->tm_mday = bcd2bin(regs[RV3029C2_A_DT-RV3029C2_A_SC] & 0x3f);
	tm->tm_mon = bcd2bin(regs[RV3029C2_A_MO-RV3029C2_A_SC] & 0x1f) - 1;
	tm->tm_year = bcd2bin(regs[RV3029C2_A_YR-RV3029C2_A_SC] & 0x7f) + 100;
	tm->tm_wday = bcd2bin(regs[RV3029C2_A_DW-RV3029C2_A_SC] & 0x07) - 1;

	return 0;
	}

	static int
	rv3029c2_rtc_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	return rv3029c2_i2c_read_alarm(to_i2c_client(dev), alarm);
	}

	static int rv3029c2_rtc_i2c_alarm_set_irq(struct i2c_client *client,
	int enable)
	{
	int ret;
	u8 buf[1];

	/* enable AIE irq */
	ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_CTRL, buf, 1);
	if (ret < 0) {
	dev_err(&client->dev, "can't read INT reg\n");
	return ret;
	}
	if (enable)
	buf[0] \|= RV3029C2_IRQ_CTRL_AIE;
	else
	buf[0] &= ~RV3029C2_IRQ_CTRL_AIE;

	ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_CTRL, buf, 1);
	if (ret < 0) {
	dev_err(&client->dev, "can't set INT reg\n");
	return ret;
	}

	return 0;
	}

	static int rv3029c2_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 = rv3029c2_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return -EIO;
	}
	regs[RV3029C2_A_SC-RV3029C2_A_SC] = bin2bcd(tm->tm_sec & 0x7f);
	regs[RV3029C2_A_MN-RV3029C2_A_SC] = bin2bcd(tm->tm_min & 0x7f);
	regs[RV3029C2_A_HR-RV3029C2_A_SC] = bin2bcd(tm->tm_hour & 0x3f);
	regs[RV3029C2_A_DT-RV3029C2_A_SC] = bin2bcd(tm->tm_mday & 0x3f);
	regs[RV3029C2_A_MO-RV3029C2_A_SC] = bin2bcd((tm->tm_mon & 0x1f) - 1);
	regs[RV3029C2_A_DW-RV3029C2_A_SC] = bin2bcd((tm->tm_wday & 7) - 1);
	regs[RV3029C2_A_YR-RV3029C2_A_SC] = bin2bcd((tm->tm_year & 0x7f) - 100);

	ret = rv3029c2_i2c_write_regs(client, RV3029C2_A_SC, regs,
	RV3029C2_ALARM_SECTION_LEN);
	if (ret < 0)
	return ret;

	if (alarm->enabled) {
	u8 buf[1];

	/* clear AF flag */
	ret = rv3029c2_i2c_read_regs(client, RV3029C2_IRQ_FLAGS,
	buf, 1);
	if (ret < 0) {
	dev_err(&client->dev, "can't read alarm flag\n");
	return ret;
	}
	buf[0] &= ~RV3029C2_IRQ_FLAGS_AF;
	ret = rv3029c2_i2c_write_regs(client, RV3029C2_IRQ_FLAGS,
	buf, 1);
	if (ret < 0) {
	dev_err(&client->dev, "can't set alarm flag\n");
	return ret;
	}
	/* enable AIE irq */
	ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 1);
	if (ret)
	return ret;

	dev_dbg(&client->dev, "alarm IRQ armed\n");
	} else {
	/* disable AIE irq */
	ret = rv3029c2_rtc_i2c_alarm_set_irq(client, 0);
	if (ret)
	return ret;

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

	return 0;
	}

	static int rv3029c2_rtc_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	return rv3029c2_rtc_i2c_set_alarm(to_i2c_client(dev), alarm);
	}

	static int
	rv3029c2_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[RV3029C2_W_SEC-RV3029C2_W_SEC] = bin2bcd(tm->tm_sec);
	regs[RV3029C2_W_MINUTES-RV3029C2_W_SEC] = bin2bcd(tm->tm_min);
	regs[RV3029C2_W_HOURS-RV3029C2_W_SEC] = bin2bcd(tm->tm_hour);
	regs[RV3029C2_W_DATE-RV3029C2_W_SEC] = bin2bcd(tm->tm_mday);
	regs[RV3029C2_W_MONTHS-RV3029C2_W_SEC] = bin2bcd(tm->tm_mon+1);
	regs[RV3029C2_W_DAYS-RV3029C2_W_SEC] = bin2bcd((tm->tm_wday & 7)+1);
	regs[RV3029C2_W_YEARS-RV3029C2_W_SEC] = bin2bcd(tm->tm_year - 100);

	ret = rv3029c2_i2c_write_regs(client, RV3029C2_W_SEC, regs,
	RV3029C2_WATCH_SECTION_LEN);
	if (ret < 0)
	return ret;

	ret = rv3029c2_i2c_get_sr(client, regs);
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return ret;
	}
	/* clear PON bit */
	ret = rv3029c2_i2c_set_sr(client, (regs[0] & ~RV3029C2_STATUS_PON));
	if (ret < 0) {
	dev_err(&client->dev, "%s: reading SR failed\n", __func__);
	return ret;
	}

	return 0;
	}

	static int rv3029c2_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	return rv3029c2_i2c_set_time(to_i2c_client(dev), tm);
	}

	static const struct rtc_class_ops rv3029c2_rtc_ops = {
	.read_time = rv3029c2_rtc_read_time,
	.set_time = rv3029c2_rtc_set_time,
	.read_alarm = rv3029c2_rtc_read_alarm,
	.set_alarm = rv3029c2_rtc_set_alarm,
	};

	static struct i2c_device_id rv3029c2_id[] = {
	{ "rv3029c2", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, rv3029c2_id);

	static int rv3029c2_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;

	rtc = devm_rtc_device_register(&client->dev, client->name,
	&rv3029c2_rtc_ops, THIS_MODULE);

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

	i2c_set_clientdata(client, rtc);

	rc = rv3029c2_i2c_get_sr(client, buf);
	if (rc < 0) {
	dev_err(&client->dev, "reading status failed\n");
	return rc;
	}

	return 0;
	}

	static struct i2c_driver rv3029c2_driver = {
	.driver = {
	.name = "rtc-rv3029c2",
	},
	.probe = rv3029c2_probe,
	.id_table = rv3029c2_id,
	};

	module_i2c_driver(rv3029c2_driver);

	MODULE_AUTHOR("Gregory Hermant <gregory.hermant@calao-systems.com>");
	MODULE_DESCRIPTION("Micro Crystal RV3029C2 RTC driver");
	MODULE_LICENSE("GPL");