drivers/rtc/rtc-rx8025.c - linux - Git at Google

 /*
  * Driver for Epson's RTC module RX-8025 SA/NB
  *
  * Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
  *
  * Copyright (C) 2005 by Digi International Inc.
  * All rights reserved.
  *
  * Modified by fengjh at rising.com.cn
  * <lm-sensors@lm-sensors.org>
  * 2006.11
  *
  * Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
  * Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
  * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.com>
  *
  * 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/bcd.h>
 #include <linux/bitops.h>
 #include <linux/i2c.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/rtc.h>

 /* Register definitions */
 #define RX8025_REG_SEC		0x00
 #define RX8025_REG_MIN		0x01
 #define RX8025_REG_HOUR		0x02
 #define RX8025_REG_WDAY		0x03
 #define RX8025_REG_MDAY		0x04
 #define RX8025_REG_MONTH	0x05
 #define RX8025_REG_YEAR		0x06
 #define RX8025_REG_DIGOFF	0x07
 #define RX8025_REG_ALWMIN	0x08
 #define RX8025_REG_ALWHOUR	0x09
 #define RX8025_REG_ALWWDAY	0x0a
 #define RX8025_REG_ALDMIN	0x0b
 #define RX8025_REG_ALDHOUR	0x0c
 /* 0x0d is reserved */
 #define RX8025_REG_CTRL1	0x0e
 #define RX8025_REG_CTRL2	0x0f

 #define RX8025_BIT_CTRL1_CT	(7 << 0)
 /* 1 Hz periodic level irq */
 #define RX8025_BIT_CTRL1_CT_1HZ	4
 #define RX8025_BIT_CTRL1_TEST	BIT(3)
 #define RX8025_BIT_CTRL1_1224	BIT(5)
 #define RX8025_BIT_CTRL1_DALE	BIT(6)
 #define RX8025_BIT_CTRL1_WALE	BIT(7)

 #define RX8025_BIT_CTRL2_DAFG	BIT(0)
 #define RX8025_BIT_CTRL2_WAFG	BIT(1)
 #define RX8025_BIT_CTRL2_CTFG	BIT(2)
 #define RX8025_BIT_CTRL2_PON	BIT(4)
 #define RX8025_BIT_CTRL2_XST	BIT(5)
 #define RX8025_BIT_CTRL2_VDET	BIT(6)

 /* Clock precision adjustment */
 #define RX8025_ADJ_RESOLUTION	3050 /* in ppb */
 #define RX8025_ADJ_DATA_MAX	62
 #define RX8025_ADJ_DATA_MIN	-62

 static const struct i2c_device_id rx8025_id[] = {
 	{ "rx8025", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, rx8025_id);

 struct rx8025_data {
 	struct i2c_client *client;
 	struct rtc_device *rtc;
 	u8 ctrl1;
 };

 static s32 rx8025_read_reg(const struct i2c_client *client, u8 number)
 {
 	return i2c_smbus_read_byte_data(client, number << 4);
 }

 static int rx8025_read_regs(const struct i2c_client *client,
 			    u8 number, u8 length, u8 *values)
 {
 	int ret = i2c_smbus_read_i2c_block_data(client, number << 4, length,
 						values);
 	if (ret != length)
 		return ret < 0 ? ret : -EIO;

 	return 0;
 }

 static s32 rx8025_write_reg(const struct i2c_client *client, u8 number,
 			    u8 value)
 {
 	return i2c_smbus_write_byte_data(client, number << 4, value);
 }

 static s32 rx8025_write_regs(const struct i2c_client *client,
 			     u8 number, u8 length, const u8 *values)
 {
 	return i2c_smbus_write_i2c_block_data(client, number << 4,
 					      length, values);
 }

 static int rx8025_check_validity(struct device *dev)
 {
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	int ctrl2;

 	ctrl2 = rx8025_read_reg(rx8025->client, RX8025_REG_CTRL2);
 	if (ctrl2 < 0)
 		return ctrl2;

 	if (ctrl2 & RX8025_BIT_CTRL2_VDET)
 		dev_warn(dev, "power voltage drop detected\n");

 	if (ctrl2 & RX8025_BIT_CTRL2_PON) {
 		dev_warn(dev, "power-on reset detected, date is invalid\n");
 		return -EINVAL;
 	}

 	if (!(ctrl2 & RX8025_BIT_CTRL2_XST)) {
 		dev_warn(dev, "crystal stopped, date is invalid\n");
 		return -EINVAL;
 	}

 	return 0;
 }

 static int rx8025_reset_validity(struct i2c_client *client)
 {
 	int ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);

 	if (ctrl2 < 0)
 		return ctrl2;

 	ctrl2 &= ~(RX8025_BIT_CTRL2_PON | RX8025_BIT_CTRL2_VDET);

 	return rx8025_write_reg(client, RX8025_REG_CTRL2,
 				ctrl2 | RX8025_BIT_CTRL2_XST);
 }

 static irqreturn_t rx8025_handle_irq(int irq, void *dev_id)
 {
 	struct i2c_client *client = dev_id;
 	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
 	struct mutex *lock = &rx8025->rtc->ops_lock;
 	int status;

 	mutex_lock(lock);
 	status = rx8025_read_reg(client, RX8025_REG_CTRL2);
 	if (status < 0)
 		goto out;

 	if (!(status & RX8025_BIT_CTRL2_XST))
 		dev_warn(&client->dev, "Oscillation stop was detected,"
 			 "you may have to readjust the clock\n");

 	if (status & RX8025_BIT_CTRL2_CTFG) {
 		/* periodic */
 		status &= ~RX8025_BIT_CTRL2_CTFG;
 		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
 	}

 	if (status & RX8025_BIT_CTRL2_DAFG) {
 		/* alarm */
 		status &= RX8025_BIT_CTRL2_DAFG;
 		if (rx8025_write_reg(client, RX8025_REG_CTRL1,
 				     rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
 			goto out;
 		rtc_update_irq(rx8025->rtc, 1, RTC_AF | RTC_IRQF);
 	}

 out:
 	mutex_unlock(lock);

 	return IRQ_HANDLED;
 }

 static int rx8025_get_time(struct device *dev, struct rtc_time *dt)
 {
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	u8 date[7];
 	int err;

 	err = rx8025_check_validity(dev);
 	if (err)
 		return err;

 	err = rx8025_read_regs(rx8025->client, RX8025_REG_SEC, 7, date);
 	if (err)
 		return err;

 	dev_dbg(dev, "%s: read %7ph\n", __func__, date);

 	dt->tm_sec = bcd2bin(date[RX8025_REG_SEC] & 0x7f);
 	dt->tm_min = bcd2bin(date[RX8025_REG_MIN] & 0x7f);
 	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
 		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x3f);
 	else
 		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x1f) % 12
 			+ (date[RX8025_REG_HOUR] & 0x20 ? 12 : 0);

 	dt->tm_mday = bcd2bin(date[RX8025_REG_MDAY] & 0x3f);
 	dt->tm_mon = bcd2bin(date[RX8025_REG_MONTH] & 0x1f) - 1;
 	dt->tm_year = bcd2bin(date[RX8025_REG_YEAR]) + 100;

 	dev_dbg(dev, "%s: date %ptRr\n", __func__, dt);

 	return 0;
 }

 static int rx8025_set_time(struct device *dev, struct rtc_time *dt)
 {
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	u8 date[7];
 	int ret;

 	if ((dt->tm_year < 100) || (dt->tm_year > 199))
 		return -EINVAL;

 	/*
 	 * Here the read-only bits are written as "0".  I'm not sure if that
 	 * is sound.
 	 */
 	date[RX8025_REG_SEC] = bin2bcd(dt->tm_sec);
 	date[RX8025_REG_MIN] = bin2bcd(dt->tm_min);
 	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
 		date[RX8025_REG_HOUR] = bin2bcd(dt->tm_hour);
 	else
 		date[RX8025_REG_HOUR] = (dt->tm_hour >= 12 ? 0x20 : 0)
 			| bin2bcd((dt->tm_hour + 11) % 12 + 1);

 	date[RX8025_REG_WDAY] = bin2bcd(dt->tm_wday);
 	date[RX8025_REG_MDAY] = bin2bcd(dt->tm_mday);
 	date[RX8025_REG_MONTH] = bin2bcd(dt->tm_mon + 1);
 	date[RX8025_REG_YEAR] = bin2bcd(dt->tm_year - 100);

 	dev_dbg(dev, "%s: write %7ph\n", __func__, date);

 	ret = rx8025_write_regs(rx8025->client, RX8025_REG_SEC, 7, date);
 	if (ret < 0)
 		return ret;

 	return rx8025_reset_validity(rx8025->client);
 }

 static int rx8025_init_client(struct i2c_client *client)
 {
 	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
 	u8 ctrl[2], ctrl2;
 	int need_clear = 0;
 	int err;

 	err = rx8025_read_regs(rx8025->client, RX8025_REG_CTRL1, 2, ctrl);
 	if (err)
 		goto out;

 	/* Keep test bit zero ! */
 	rx8025->ctrl1 = ctrl[0] & ~RX8025_BIT_CTRL1_TEST;

 	if (ctrl[1] & (RX8025_BIT_CTRL2_DAFG | RX8025_BIT_CTRL2_WAFG)) {
 		dev_warn(&client->dev, "Alarm was detected\n");
 		need_clear = 1;
 	}

 	if (ctrl[1] & RX8025_BIT_CTRL2_CTFG)
 		need_clear = 1;

 	if (need_clear) {
 		ctrl2 = ctrl[1];
 		ctrl2 &= ~(RX8025_BIT_CTRL2_CTFG | RX8025_BIT_CTRL2_WAFG |
 			   RX8025_BIT_CTRL2_DAFG);

 		err = rx8025_write_reg(client, RX8025_REG_CTRL2, ctrl2);
 	}
 out:
 	return err;
 }

 /* Alarm support */
 static int rx8025_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 {
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	struct i2c_client *client = rx8025->client;
 	u8 ald[2];
 	int ctrl2, err;

 	if (client->irq <= 0)
 		return -EINVAL;

 	err = rx8025_read_regs(client, RX8025_REG_ALDMIN, 2, ald);
 	if (err)
 		return err;

 	ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
 	if (ctrl2 < 0)
 		return ctrl2;

 	dev_dbg(dev, "%s: read alarm 0x%02x 0x%02x ctrl2 %02x\n",
 		__func__, ald[0], ald[1], ctrl2);

 	/* Hardware alarms precision is 1 minute! */
 	t->time.tm_sec = 0;
 	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
 	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
 		t->time.tm_hour = bcd2bin(ald[1] & 0x3f);
 	else
 		t->time.tm_hour = bcd2bin(ald[1] & 0x1f) % 12
 			+ (ald[1] & 0x20 ? 12 : 0);

 	dev_dbg(dev, "%s: date: %ptRr\n", __func__, &t->time);
 	t->enabled = !!(rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE);
 	t->pending = (ctrl2 & RX8025_BIT_CTRL2_DAFG) && t->enabled;

 	return err;
 }

 static int rx8025_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	u8 ald[2];
 	int err;

 	if (client->irq <= 0)
 		return -EINVAL;

 	/*
 	 * Hardware alarm precision is 1 minute!
 	 * round up to nearest minute
 	 */
 	if (t->time.tm_sec) {
 		time64_t alarm_time = rtc_tm_to_time64(&t->time);

 		alarm_time += 60 - t->time.tm_sec;
 		rtc_time64_to_tm(alarm_time, &t->time);
 	}

 	ald[0] = bin2bcd(t->time.tm_min);
 	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
 		ald[1] = bin2bcd(t->time.tm_hour);
 	else
 		ald[1] = (t->time.tm_hour >= 12 ? 0x20 : 0)
 			| bin2bcd((t->time.tm_hour + 11) % 12 + 1);

 	dev_dbg(dev, "%s: write 0x%02x 0x%02x\n", __func__, ald[0], ald[1]);

 	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE) {
 		rx8025->ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
 		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
 				       rx8025->ctrl1);
 		if (err)
 			return err;
 	}
 	err = rx8025_write_regs(rx8025->client, RX8025_REG_ALDMIN, 2, ald);
 	if (err)
 		return err;

 	if (t->enabled) {
 		rx8025->ctrl1 |= RX8025_BIT_CTRL1_DALE;
 		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
 				       rx8025->ctrl1);
 		if (err)
 			return err;
 	}

 	return 0;
 }

 static int rx8025_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
 	u8 ctrl1;
 	int err;

 	ctrl1 = rx8025->ctrl1;
 	if (enabled)
 		ctrl1 |= RX8025_BIT_CTRL1_DALE;
 	else
 		ctrl1 &= ~RX8025_BIT_CTRL1_DALE;

 	if (ctrl1 != rx8025->ctrl1) {
 		rx8025->ctrl1 = ctrl1;
 		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
 				       rx8025->ctrl1);
 		if (err)
 			return err;
 	}
 	return 0;
 }

 static const struct rtc_class_ops rx8025_rtc_ops = {
 	.read_time = rx8025_get_time,
 	.set_time = rx8025_set_time,
 	.read_alarm = rx8025_read_alarm,
 	.set_alarm = rx8025_set_alarm,
 	.alarm_irq_enable = rx8025_alarm_irq_enable,
 };

 /*
  * Clock precision adjustment support
  *
  * According to the RX8025 SA/NB application manual the frequency and
  * temperature characteristics can be approximated using the following
  * equation:
  *
  *   df = a * (ut - t)**2
  *
  *   df: Frequency deviation in any temperature
  *   a : Coefficient = (-35 +-5) * 10**-9
  *   ut: Ultimate temperature in degree = +25 +-5 degree
  *   t : Any temperature in degree
  *
  * Note that the clock adjustment in ppb must be entered (which is
  * the negative value of the deviation).
  */
 static int rx8025_get_clock_adjust(struct device *dev, int *adj)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int digoff;

 	digoff = rx8025_read_reg(client, RX8025_REG_DIGOFF);
 	if (digoff < 0)
 		return digoff;

 	*adj = digoff >= 64 ? digoff - 128 : digoff;
 	if (*adj > 0)
 		(*adj)--;
 	*adj *= -RX8025_ADJ_RESOLUTION;

 	return 0;
 }

 static int rx8025_set_clock_adjust(struct device *dev, int adj)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	u8 digoff;
 	int err;

 	adj /= -RX8025_ADJ_RESOLUTION;
 	if (adj > RX8025_ADJ_DATA_MAX)
 		adj = RX8025_ADJ_DATA_MAX;
 	else if (adj < RX8025_ADJ_DATA_MIN)
 		adj = RX8025_ADJ_DATA_MIN;
 	else if (adj > 0)
 		adj++;
 	else if (adj < 0)
 		adj += 128;
 	digoff = adj;

 	err = rx8025_write_reg(client, RX8025_REG_DIGOFF, digoff);
 	if (err)
 		return err;

 	dev_dbg(dev, "%s: write 0x%02x\n", __func__, digoff);

 	return 0;
 }

 static ssize_t rx8025_sysfs_show_clock_adjust(struct device *dev,
 					      struct device_attribute *attr,
 					      char *buf)
 {
 	int err, adj;

 	err = rx8025_get_clock_adjust(dev, &adj);
 	if (err)
 		return err;

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

 static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
 					       struct device_attribute *attr,
 					       const char *buf, size_t count)
 {
 	int adj, err;

 	if (sscanf(buf, "%i", &adj) != 1)
 		return -EINVAL;

 	err = rx8025_set_clock_adjust(dev, adj);

 	return err ? err : count;
 }

 static DEVICE_ATTR(clock_adjust_ppb, S_IRUGO | S_IWUSR,
 		   rx8025_sysfs_show_clock_adjust,
 		   rx8025_sysfs_store_clock_adjust);

 static int rx8025_sysfs_register(struct device *dev)
 {
 	return device_create_file(dev, &dev_attr_clock_adjust_ppb);
 }

 static void rx8025_sysfs_unregister(struct device *dev)
 {
 	device_remove_file(dev, &dev_attr_clock_adjust_ppb);
 }

 static int rx8025_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
 	struct rx8025_data *rx8025;
 	int err = 0;

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
 				     | I2C_FUNC_SMBUS_I2C_BLOCK)) {
 		dev_err(&adapter->dev,
 			"doesn't support required functionality\n");
 		return -EIO;
 	}

 	rx8025 = devm_kzalloc(&client->dev, sizeof(*rx8025), GFP_KERNEL);
 	if (!rx8025)
 		return -ENOMEM;

 	rx8025->client = client;
 	i2c_set_clientdata(client, rx8025);

 	err = rx8025_init_client(client);
 	if (err)
 		return err;

 	rx8025->rtc = devm_rtc_device_register(&client->dev, client->name,
 					  &rx8025_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rx8025->rtc)) {
 		dev_err(&client->dev, "unable to register the class device\n");
 		return PTR_ERR(rx8025->rtc);
 	}

 	if (client->irq > 0) {
 		dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
 		err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
 						rx8025_handle_irq,
 						IRQF_ONESHOT,
 						"rx8025", client);
 		if (err) {
 			dev_err(&client->dev, "unable to request IRQ, alarms disabled\n");
 			client->irq = 0;
 		}
 	}

 	rx8025->rtc->max_user_freq = 1;

 	/* the rx8025 alarm only supports a minute accuracy */
 	rx8025->rtc->uie_unsupported = 1;

 	err = rx8025_sysfs_register(&client->dev);
 	return err;
 }

 static int rx8025_remove(struct i2c_client *client)
 {
 	rx8025_sysfs_unregister(&client->dev);
 	return 0;
 }

 static struct i2c_driver rx8025_driver = {
 	.driver = {
 		.name = "rtc-rx8025",
 	},
 	.probe		= rx8025_probe,
 	.remove		= rx8025_remove,
 	.id_table	= rx8025_id,
 };

 module_i2c_driver(rx8025_driver);

 MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
 MODULE_DESCRIPTION("RX-8025 SA/NB RTC driver");
 MODULE_LICENSE("GPL");
	/*
	* Driver for Epson's RTC module RX-8025 SA/NB
	*
	* Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
	*
	* Copyright (C) 2005 by Digi International Inc.
	* All rights reserved.
	*
	* Modified by fengjh at rising.com.cn
	* <lm-sensors@lm-sensors.org>
	* 2006.11
	*
	* Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
	* Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
	* Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.com>
	*
	* 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/bcd.h>
	#include <linux/bitops.h>
	#include <linux/i2c.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/rtc.h>

	/* Register definitions */
	#define RX8025_REG_SEC 0x00
	#define RX8025_REG_MIN 0x01
	#define RX8025_REG_HOUR 0x02
	#define RX8025_REG_WDAY 0x03
	#define RX8025_REG_MDAY 0x04
	#define RX8025_REG_MONTH 0x05
	#define RX8025_REG_YEAR 0x06
	#define RX8025_REG_DIGOFF 0x07
	#define RX8025_REG_ALWMIN 0x08
	#define RX8025_REG_ALWHOUR 0x09
	#define RX8025_REG_ALWWDAY 0x0a
	#define RX8025_REG_ALDMIN 0x0b
	#define RX8025_REG_ALDHOUR 0x0c
	/* 0x0d is reserved */
	#define RX8025_REG_CTRL1 0x0e
	#define RX8025_REG_CTRL2 0x0f

	#define RX8025_BIT_CTRL1_CT (7 << 0)
	/* 1 Hz periodic level irq */
	#define RX8025_BIT_CTRL1_CT_1HZ 4
	#define RX8025_BIT_CTRL1_TEST BIT(3)
	#define RX8025_BIT_CTRL1_1224 BIT(5)
	#define RX8025_BIT_CTRL1_DALE BIT(6)
	#define RX8025_BIT_CTRL1_WALE BIT(7)

	#define RX8025_BIT_CTRL2_DAFG BIT(0)
	#define RX8025_BIT_CTRL2_WAFG BIT(1)
	#define RX8025_BIT_CTRL2_CTFG BIT(2)
	#define RX8025_BIT_CTRL2_PON BIT(4)
	#define RX8025_BIT_CTRL2_XST BIT(5)
	#define RX8025_BIT_CTRL2_VDET BIT(6)

	/* Clock precision adjustment */
	#define RX8025_ADJ_RESOLUTION 3050 /* in ppb */
	#define RX8025_ADJ_DATA_MAX 62
	#define RX8025_ADJ_DATA_MIN -62

	static const struct i2c_device_id rx8025_id[] = {
	{ "rx8025", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, rx8025_id);

	struct rx8025_data {
	struct i2c_client *client;
	struct rtc_device *rtc;
	u8 ctrl1;
	};

	static s32 rx8025_read_reg(const struct i2c_client *client, u8 number)
	{
	return i2c_smbus_read_byte_data(client, number << 4);
	}

	static int rx8025_read_regs(const struct i2c_client *client,
	u8 number, u8 length, u8 *values)
	{
	int ret = i2c_smbus_read_i2c_block_data(client, number << 4, length,
	values);
	if (ret != length)
	return ret < 0 ? ret : -EIO;

	return 0;
	}

	static s32 rx8025_write_reg(const struct i2c_client *client, u8 number,
	u8 value)
	{
	return i2c_smbus_write_byte_data(client, number << 4, value);
	}

	static s32 rx8025_write_regs(const struct i2c_client *client,
	u8 number, u8 length, const u8 *values)
	{
	return i2c_smbus_write_i2c_block_data(client, number << 4,
	length, values);
	}

	static int rx8025_check_validity(struct device *dev)
	{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	int ctrl2;

	ctrl2 = rx8025_read_reg(rx8025->client, RX8025_REG_CTRL2);
	if (ctrl2 < 0)
	return ctrl2;

	if (ctrl2 & RX8025_BIT_CTRL2_VDET)
	dev_warn(dev, "power voltage drop detected\n");

	if (ctrl2 & RX8025_BIT_CTRL2_PON) {
	dev_warn(dev, "power-on reset detected, date is invalid\n");
	return -EINVAL;
	}

	if (!(ctrl2 & RX8025_BIT_CTRL2_XST)) {
	dev_warn(dev, "crystal stopped, date is invalid\n");
	return -EINVAL;
	}

	return 0;
	}

	static int rx8025_reset_validity(struct i2c_client *client)
	{
	int ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);

	if (ctrl2 < 0)
	return ctrl2;

	ctrl2 &= ~(RX8025_BIT_CTRL2_PON \| RX8025_BIT_CTRL2_VDET);

	return rx8025_write_reg(client, RX8025_REG_CTRL2,
	ctrl2 \| RX8025_BIT_CTRL2_XST);
	}

	static irqreturn_t rx8025_handle_irq(int irq, void *dev_id)
	{
	struct i2c_client *client = dev_id;
	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
	struct mutex *lock = &rx8025->rtc->ops_lock;
	int status;

	mutex_lock(lock);
	status = rx8025_read_reg(client, RX8025_REG_CTRL2);
	if (status < 0)
	goto out;

	if (!(status & RX8025_BIT_CTRL2_XST))
	dev_warn(&client->dev, "Oscillation stop was detected,"
	"you may have to readjust the clock\n");

	if (status & RX8025_BIT_CTRL2_CTFG) {
	/* periodic */
	status &= ~RX8025_BIT_CTRL2_CTFG;
	rtc_update_irq(rx8025->rtc, 1, RTC_PF \| RTC_IRQF);
	}

	if (status & RX8025_BIT_CTRL2_DAFG) {
	/* alarm */
	status &= RX8025_BIT_CTRL2_DAFG;
	if (rx8025_write_reg(client, RX8025_REG_CTRL1,
	rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
	goto out;
	rtc_update_irq(rx8025->rtc, 1, RTC_AF \| RTC_IRQF);
	}

	out:
	mutex_unlock(lock);

	return IRQ_HANDLED;
	}

	static int rx8025_get_time(struct device dev, struct rtc_time dt)
	{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 date[7];
	int err;

	err = rx8025_check_validity(dev);
	if (err)
	return err;

	err = rx8025_read_regs(rx8025->client, RX8025_REG_SEC, 7, date);
	if (err)
	return err;

	dev_dbg(dev, "%s: read %7ph\n", __func__, date);

	dt->tm_sec = bcd2bin(date[RX8025_REG_SEC] & 0x7f);
	dt->tm_min = bcd2bin(date[RX8025_REG_MIN] & 0x7f);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
	dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x3f);
	else
	dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x1f) % 12
	+ (date[RX8025_REG_HOUR] & 0x20 ? 12 : 0);

	dt->tm_mday = bcd2bin(date[RX8025_REG_MDAY] & 0x3f);
	dt->tm_mon = bcd2bin(date[RX8025_REG_MONTH] & 0x1f) - 1;
	dt->tm_year = bcd2bin(date[RX8025_REG_YEAR]) + 100;

	dev_dbg(dev, "%s: date %ptRr\n", __func__, dt);

	return 0;
	}

	static int rx8025_set_time(struct device dev, struct rtc_time dt)
	{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 date[7];
	int ret;

	if ((dt->tm_year < 100) \|\| (dt->tm_year > 199))
	return -EINVAL;

	/*
	* Here the read-only bits are written as "0". I'm not sure if that
	* is sound.
	*/
	date[RX8025_REG_SEC] = bin2bcd(dt->tm_sec);
	date[RX8025_REG_MIN] = bin2bcd(dt->tm_min);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
	date[RX8025_REG_HOUR] = bin2bcd(dt->tm_hour);
	else
	date[RX8025_REG_HOUR] = (dt->tm_hour >= 12 ? 0x20 : 0)
	\| bin2bcd((dt->tm_hour + 11) % 12 + 1);

	date[RX8025_REG_WDAY] = bin2bcd(dt->tm_wday);
	date[RX8025_REG_MDAY] = bin2bcd(dt->tm_mday);
	date[RX8025_REG_MONTH] = bin2bcd(dt->tm_mon + 1);
	date[RX8025_REG_YEAR] = bin2bcd(dt->tm_year - 100);

	dev_dbg(dev, "%s: write %7ph\n", __func__, date);

	ret = rx8025_write_regs(rx8025->client, RX8025_REG_SEC, 7, date);
	if (ret < 0)
	return ret;

	return rx8025_reset_validity(rx8025->client);
	}

	static int rx8025_init_client(struct i2c_client *client)
	{
	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
	u8 ctrl[2], ctrl2;
	int need_clear = 0;
	int err;

	err = rx8025_read_regs(rx8025->client, RX8025_REG_CTRL1, 2, ctrl);
	if (err)
	goto out;

	/* Keep test bit zero ! */
	rx8025->ctrl1 = ctrl[0] & ~RX8025_BIT_CTRL1_TEST;

	if (ctrl[1] & (RX8025_BIT_CTRL2_DAFG \| RX8025_BIT_CTRL2_WAFG)) {
	dev_warn(&client->dev, "Alarm was detected\n");
	need_clear = 1;
	}

	if (ctrl[1] & RX8025_BIT_CTRL2_CTFG)
	need_clear = 1;

	if (need_clear) {
	ctrl2 = ctrl[1];
	ctrl2 &= ~(RX8025_BIT_CTRL2_CTFG \| RX8025_BIT_CTRL2_WAFG \|
	RX8025_BIT_CTRL2_DAFG);

	err = rx8025_write_reg(client, RX8025_REG_CTRL2, ctrl2);
	}
	out:
	return err;
	}

	/* Alarm support */
	static int rx8025_read_alarm(struct device dev, struct rtc_wkalrm t)
	{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	struct i2c_client *client = rx8025->client;
	u8 ald[2];
	int ctrl2, err;

	if (client->irq <= 0)
	return -EINVAL;

	err = rx8025_read_regs(client, RX8025_REG_ALDMIN, 2, ald);
	if (err)
	return err;

	ctrl2 = rx8025_read_reg(client, RX8025_REG_CTRL2);
	if (ctrl2 < 0)
	return ctrl2;

	dev_dbg(dev, "%s: read alarm 0x%02x 0x%02x ctrl2 %02x\n",
	__func__, ald[0], ald[1], ctrl2);

	/* Hardware alarms precision is 1 minute! */
	t->time.tm_sec = 0;
	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
	t->time.tm_hour = bcd2bin(ald[1] & 0x3f);
	else
	t->time.tm_hour = bcd2bin(ald[1] & 0x1f) % 12
	+ (ald[1] & 0x20 ? 12 : 0);

	dev_dbg(dev, "%s: date: %ptRr\n", __func__, &t->time);
	t->enabled = !!(rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE);
	t->pending = (ctrl2 & RX8025_BIT_CTRL2_DAFG) && t->enabled;

	return err;
	}

	static int rx8025_set_alarm(struct device dev, struct rtc_wkalrm t)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 ald[2];
	int err;

	if (client->irq <= 0)
	return -EINVAL;

	/*
	* Hardware alarm precision is 1 minute!
	* round up to nearest minute
	*/
	if (t->time.tm_sec) {
	time64_t alarm_time = rtc_tm_to_time64(&t->time);

	alarm_time += 60 - t->time.tm_sec;
	rtc_time64_to_tm(alarm_time, &t->time);
	}

	ald[0] = bin2bcd(t->time.tm_min);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
	ald[1] = bin2bcd(t->time.tm_hour);
	else
	ald[1] = (t->time.tm_hour >= 12 ? 0x20 : 0)
	\| bin2bcd((t->time.tm_hour + 11) % 12 + 1);

	dev_dbg(dev, "%s: write 0x%02x 0x%02x\n", __func__, ald[0], ald[1]);

	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE) {
	rx8025->ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
	err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
	rx8025->ctrl1);
	if (err)
	return err;
	}
	err = rx8025_write_regs(rx8025->client, RX8025_REG_ALDMIN, 2, ald);
	if (err)
	return err;

	if (t->enabled) {
	rx8025->ctrl1 \|= RX8025_BIT_CTRL1_DALE;
	err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
	rx8025->ctrl1);
	if (err)
	return err;
	}

	return 0;
	}

	static int rx8025_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 ctrl1;
	int err;

	ctrl1 = rx8025->ctrl1;
	if (enabled)
	ctrl1 \|= RX8025_BIT_CTRL1_DALE;
	else
	ctrl1 &= ~RX8025_BIT_CTRL1_DALE;

	if (ctrl1 != rx8025->ctrl1) {
	rx8025->ctrl1 = ctrl1;
	err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
	rx8025->ctrl1);
	if (err)
	return err;
	}
	return 0;
	}

	static const struct rtc_class_ops rx8025_rtc_ops = {
	.read_time = rx8025_get_time,
	.set_time = rx8025_set_time,
	.read_alarm = rx8025_read_alarm,
	.set_alarm = rx8025_set_alarm,
	.alarm_irq_enable = rx8025_alarm_irq_enable,
	};

	/*
	* Clock precision adjustment support
	*
	* According to the RX8025 SA/NB application manual the frequency and
	* temperature characteristics can be approximated using the following
	* equation:
	*
	* df = a * (ut - t)**2
	*
	* df: Frequency deviation in any temperature
	* a : Coefficient = (-35 +-5) * 10**-9
	* ut: Ultimate temperature in degree = +25 +-5 degree
	* t : Any temperature in degree
	*
	* Note that the clock adjustment in ppb must be entered (which is
	* the negative value of the deviation).
	*/
	static int rx8025_get_clock_adjust(struct device dev, int adj)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int digoff;

	digoff = rx8025_read_reg(client, RX8025_REG_DIGOFF);
	if (digoff < 0)
	return digoff;

	*adj = digoff >= 64 ? digoff - 128 : digoff;
	if (*adj > 0)
	(*adj)--;
	adj = -RX8025_ADJ_RESOLUTION;

	return 0;
	}

	static int rx8025_set_clock_adjust(struct device *dev, int adj)
	{
	struct i2c_client *client = to_i2c_client(dev);
	u8 digoff;
	int err;

	adj /= -RX8025_ADJ_RESOLUTION;
	if (adj > RX8025_ADJ_DATA_MAX)
	adj = RX8025_ADJ_DATA_MAX;
	else if (adj < RX8025_ADJ_DATA_MIN)
	adj = RX8025_ADJ_DATA_MIN;
	else if (adj > 0)
	adj++;
	else if (adj < 0)
	adj += 128;
	digoff = adj;

	err = rx8025_write_reg(client, RX8025_REG_DIGOFF, digoff);
	if (err)
	return err;

	dev_dbg(dev, "%s: write 0x%02x\n", __func__, digoff);

	return 0;
	}

	static ssize_t rx8025_sysfs_show_clock_adjust(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	int err, adj;

	err = rx8025_get_clock_adjust(dev, &adj);
	if (err)
	return err;

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

	static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	int adj, err;

	if (sscanf(buf, "%i", &adj) != 1)
	return -EINVAL;

	err = rx8025_set_clock_adjust(dev, adj);

	return err ? err : count;
	}

	static DEVICE_ATTR(clock_adjust_ppb, S_IRUGO \| S_IWUSR,
	rx8025_sysfs_show_clock_adjust,
	rx8025_sysfs_store_clock_adjust);

	static int rx8025_sysfs_register(struct device *dev)
	{
	return device_create_file(dev, &dev_attr_clock_adjust_ppb);
	}

	static void rx8025_sysfs_unregister(struct device *dev)
	{
	device_remove_file(dev, &dev_attr_clock_adjust_ppb);
	}

	static int rx8025_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
	struct rx8025_data *rx8025;
	int err = 0;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
	\| I2C_FUNC_SMBUS_I2C_BLOCK)) {
	dev_err(&adapter->dev,
	"doesn't support required functionality\n");
	return -EIO;
	}

	rx8025 = devm_kzalloc(&client->dev, sizeof(*rx8025), GFP_KERNEL);
	if (!rx8025)
	return -ENOMEM;

	rx8025->client = client;
	i2c_set_clientdata(client, rx8025);

	err = rx8025_init_client(client);
	if (err)
	return err;

	rx8025->rtc = devm_rtc_device_register(&client->dev, client->name,
	&rx8025_rtc_ops, THIS_MODULE);
	if (IS_ERR(rx8025->rtc)) {
	dev_err(&client->dev, "unable to register the class device\n");
	return PTR_ERR(rx8025->rtc);
	}

	if (client->irq > 0) {
	dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
	rx8025_handle_irq,
	IRQF_ONESHOT,
	"rx8025", client);
	if (err) {
	dev_err(&client->dev, "unable to request IRQ, alarms disabled\n");
	client->irq = 0;
	}
	}

	rx8025->rtc->max_user_freq = 1;

	/* the rx8025 alarm only supports a minute accuracy */
	rx8025->rtc->uie_unsupported = 1;

	err = rx8025_sysfs_register(&client->dev);
	return err;
	}

	static int rx8025_remove(struct i2c_client *client)
	{
	rx8025_sysfs_unregister(&client->dev);
	return 0;
	}

	static struct i2c_driver rx8025_driver = {
	.driver = {
	.name = "rtc-rx8025",
	},
	.probe = rx8025_probe,
	.remove = rx8025_remove,
	.id_table = rx8025_id,
	};

	module_i2c_driver(rx8025_driver);

	MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
	MODULE_DESCRIPTION("RX-8025 SA/NB RTC driver");
	MODULE_LICENSE("GPL");