drivers/rtc/rtc-pcf8523.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2012 Avionic Design GmbH
  */

 #include <linux/bcd.h>
 #include <linux/bitfield.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 #include <linux/rtc.h>
 #include <linux/of.h>
 #include <linux/pm_wakeirq.h>

 #define PCF8523_REG_CONTROL1 0x00
 #define PCF8523_CONTROL1_CAP_SEL BIT(7)
 #define PCF8523_CONTROL1_STOP    BIT(5)
 #define PCF8523_CONTROL1_AIE    BIT(1)

 #define PCF8523_REG_CONTROL2 0x01
 #define PCF8523_CONTROL2_AF BIT(3)

 #define PCF8523_REG_CONTROL3 0x02
 #define PCF8523_CONTROL3_PM  GENMASK(7,5)
 #define PCF8523_PM_STANDBY   0x7
 #define PCF8523_CONTROL3_BLF BIT(2) /* battery low bit, read-only */
 #define PCF8523_CONTROL3_BSF BIT(3)

 #define PCF8523_REG_SECONDS  0x03
 #define PCF8523_SECONDS_OS BIT(7)

 #define PCF8523_REG_MINUTES  0x04
 #define PCF8523_REG_HOURS    0x05
 #define PCF8523_REG_DAYS     0x06
 #define PCF8523_REG_WEEKDAYS 0x07
 #define PCF8523_REG_MONTHS   0x08
 #define PCF8523_REG_YEARS    0x09

 #define PCF8523_REG_MINUTE_ALARM	0x0a
 #define PCF8523_REG_HOUR_ALARM		0x0b
 #define PCF8523_REG_DAY_ALARM		0x0c
 #define PCF8523_REG_WEEKDAY_ALARM	0x0d
 #define ALARM_DIS BIT(7)

 #define PCF8523_REG_OFFSET   0x0e
 #define PCF8523_OFFSET_MODE BIT(7)

 #define PCF8523_TMR_CLKOUT_CTRL 0x0f

 struct pcf8523 {
 	struct rtc_device *rtc;
 	struct regmap *regmap;
 };

 static int pcf8523_load_capacitance(struct pcf8523 *pcf8523, struct device_node *node)
 {
 	u32 load, value = 0;

 	load = 12500;
 	of_property_read_u32(node, "quartz-load-femtofarads", &load);

 	switch (load) {
 	default:
 		dev_warn(&pcf8523->rtc->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
 			 load);
 		fallthrough;
 	case 12500:
 		value |= PCF8523_CONTROL1_CAP_SEL;
 		break;
 	case 7000:
 		break;
 	}

 	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
 				  PCF8523_CONTROL1_CAP_SEL, value);
 }

 static irqreturn_t pcf8523_irq(int irq, void *dev_id)
 {
 	struct pcf8523 *pcf8523 = dev_id;
 	u32 value;
 	int err;

 	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL2, &value);
 	if (err < 0)
 		return IRQ_HANDLED;

 	if (value & PCF8523_CONTROL2_AF) {
 		value &= ~PCF8523_CONTROL2_AF;
 		regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL2, value);
 		rtc_update_irq(pcf8523->rtc, 1, RTC_IRQF | RTC_AF);

 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	u8 regs[10];
 	int err;

 	err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_CONTROL1, regs,
 			       sizeof(regs));
 	if (err < 0)
 		return err;

 	if ((regs[0] & PCF8523_CONTROL1_STOP) || (regs[3] & PCF8523_SECONDS_OS))
 		return -EINVAL;

 	tm->tm_sec = bcd2bin(regs[3] & 0x7f);
 	tm->tm_min = bcd2bin(regs[4] & 0x7f);
 	tm->tm_hour = bcd2bin(regs[5] & 0x3f);
 	tm->tm_mday = bcd2bin(regs[6] & 0x3f);
 	tm->tm_wday = regs[7] & 0x7;
 	tm->tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
 	tm->tm_year = bcd2bin(regs[9]) + 100;

 	return 0;
 }

 static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	u8 regs[7];
 	int err;

 	err = regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
 				 PCF8523_CONTROL1_STOP, PCF8523_CONTROL1_STOP);
 	if (err < 0)
 		return err;

 	/* This will purposely overwrite PCF8523_SECONDS_OS */
 	regs[0] = bin2bcd(tm->tm_sec);
 	regs[1] = bin2bcd(tm->tm_min);
 	regs[2] = bin2bcd(tm->tm_hour);
 	regs[3] = bin2bcd(tm->tm_mday);
 	regs[4] = tm->tm_wday;
 	regs[5] = bin2bcd(tm->tm_mon + 1);
 	regs[6] = bin2bcd(tm->tm_year - 100);

 	err = regmap_bulk_write(pcf8523->regmap, PCF8523_REG_SECONDS, regs,
 				sizeof(regs));
 	if (err < 0) {
 		/*
 		 * If the time cannot be set, restart the RTC anyway. Note
 		 * that errors are ignored if the RTC cannot be started so
 		 * that we have a chance to propagate the original error.
 		 */
 		regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
 				   PCF8523_CONTROL1_STOP, 0);
 		return err;
 	}

 	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
 				 PCF8523_CONTROL1_STOP, 0);
 }

 static int pcf8523_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	u8 regs[4];
 	u32 value;
 	int err;

 	err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_MINUTE_ALARM, regs,
 			       sizeof(regs));
 	if (err < 0)
 		return err;

 	tm->time.tm_sec = 0;
 	tm->time.tm_min = bcd2bin(regs[0] & 0x7F);
 	tm->time.tm_hour = bcd2bin(regs[1] & 0x3F);
 	tm->time.tm_mday = bcd2bin(regs[2] & 0x3F);
 	tm->time.tm_wday = bcd2bin(regs[3] & 0x7);

 	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL1, &value);
 	if (err < 0)
 		return err;
 	tm->enabled = !!(value & PCF8523_CONTROL1_AIE);

 	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL2, &value);
 	if (err < 0)
 		return err;
 	tm->pending = !!(value & PCF8523_CONTROL2_AF);

 	return 0;
 }

 static int pcf8523_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);

 	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
 				  PCF8523_CONTROL1_AIE, enabled ?
 				  PCF8523_CONTROL1_AIE : 0);
 }

 static int pcf8523_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	u8 regs[5];
 	int err;

 	err = pcf8523_irq_enable(dev, 0);
 	if (err)
 		return err;

 	err = regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL2, 0);
 	if (err < 0)
 		return err;

 	regs[0] = bin2bcd(tm->time.tm_min);
 	regs[1] = bin2bcd(tm->time.tm_hour);
 	regs[2] = bin2bcd(tm->time.tm_mday);
 	regs[3] = ALARM_DIS;

 	err = regmap_bulk_write(pcf8523->regmap, PCF8523_REG_MINUTE_ALARM, regs,
 				sizeof(regs));
 	if (err < 0)
 		return err;

 	if (tm->enabled)
 		return pcf8523_irq_enable(dev, tm->enabled);

 	return 0;
 }

 static int pcf8523_param_get(struct device *dev, struct rtc_param *param)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	int ret;
 	u32 value;

 	switch(param->param) {

 	case RTC_PARAM_BACKUP_SWITCH_MODE:
 		ret = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
 		if (ret < 0)
 			return ret;

 		value = FIELD_GET(PCF8523_CONTROL3_PM, value);

 		switch(value) {
 		case 0x0:
 		case 0x4:
 			param->uvalue = RTC_BSM_LEVEL;
 			break;
 		case 0x1:
 		case 0x5:
 			param->uvalue = RTC_BSM_DIRECT;
 			break;
 		case PCF8523_PM_STANDBY:
 			param->uvalue = RTC_BSM_STANDBY;
 			break;
 		default:
 			param->uvalue = RTC_BSM_DISABLED;
 		}

 		break;

 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int pcf8523_param_set(struct device *dev, struct rtc_param *param)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	u8 mode;

 	switch(param->param) {
 	case RTC_PARAM_BACKUP_SWITCH_MODE:
 		switch (param->uvalue) {
 		case RTC_BSM_DISABLED:
 			mode = 0x2;
 			break;
 		case RTC_BSM_DIRECT:
 			mode = 0x1;
 			break;
 		case RTC_BSM_LEVEL:
 			mode = 0x0;
 			break;
 		case RTC_BSM_STANDBY:
 			mode = PCF8523_PM_STANDBY;
 			break;
 		default:
 			return -EINVAL;
 		}

 		return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL3,
 					  PCF8523_CONTROL3_PM,
 					  FIELD_PREP(PCF8523_CONTROL3_PM, mode));

 		break;

 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
 			     unsigned long arg)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	unsigned int flags = 0;
 	u32 value;
 	int ret;

 	switch (cmd) {
 	case RTC_VL_READ:
 		ret = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
 		if (ret < 0)
 			return ret;

 		if (value & PCF8523_CONTROL3_BLF)
 			flags |= RTC_VL_BACKUP_LOW;

 		ret = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS, &value);
 		if (ret < 0)
 			return ret;

 		if (value & PCF8523_SECONDS_OS)
 			flags |= RTC_VL_DATA_INVALID;

 		return put_user(flags, (unsigned int __user *)arg);

 	default:
 		return -ENOIOCTLCMD;
 	}
 }

 static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	int err;
 	u32 value;
 	s8 val;

 	err = regmap_read(pcf8523->regmap, PCF8523_REG_OFFSET, &value);
 	if (err < 0)
 		return err;

 	/* sign extend the 7-bit offset value */
 	val = value << 1;
 	*offset = (value & PCF8523_OFFSET_MODE ? 4069 : 4340) * (val >> 1);

 	return 0;
 }

 static int pcf8523_rtc_set_offset(struct device *dev, long offset)
 {
 	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
 	long reg_m0, reg_m1;
 	u32 value;

 	reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
 	reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);

 	if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
 		value = reg_m0 & 0x7f;
 	else
 		value = (reg_m1 & 0x7f) | PCF8523_OFFSET_MODE;

 	return regmap_write(pcf8523->regmap, PCF8523_REG_OFFSET, value);
 }

 static const struct rtc_class_ops pcf8523_rtc_ops = {
 	.read_time = pcf8523_rtc_read_time,
 	.set_time = pcf8523_rtc_set_time,
 	.read_alarm = pcf8523_rtc_read_alarm,
 	.set_alarm = pcf8523_rtc_set_alarm,
 	.alarm_irq_enable = pcf8523_irq_enable,
 	.ioctl = pcf8523_rtc_ioctl,
 	.read_offset = pcf8523_rtc_read_offset,
 	.set_offset = pcf8523_rtc_set_offset,
 	.param_get = pcf8523_param_get,
 	.param_set = pcf8523_param_set,
 };

 static const struct regmap_config regmap_config = {
         .reg_bits = 8,
         .val_bits = 8,
         .max_register = 0x13,
 };

 static int pcf8523_probe(struct i2c_client *client)
 {
 	struct pcf8523 *pcf8523;
 	struct rtc_device *rtc;
 	bool wakeup_source = false;
 	u32 value;
 	int err;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;

 	pcf8523 = devm_kzalloc(&client->dev, sizeof(struct pcf8523), GFP_KERNEL);
 	if (!pcf8523)
 		return -ENOMEM;

 	pcf8523->regmap = devm_regmap_init_i2c(client, &regmap_config);
 	if (IS_ERR(pcf8523->regmap))
 		return PTR_ERR(pcf8523->regmap);

 	i2c_set_clientdata(client, pcf8523);

 	rtc = devm_rtc_allocate_device(&client->dev);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 	pcf8523->rtc = rtc;

 	err = pcf8523_load_capacitance(pcf8523, client->dev.of_node);
 	if (err < 0)
 		dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
 			 err);

 	err = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS, &value);
 	if (err < 0)
 		return err;

 	if (value & PCF8523_SECONDS_OS) {
 		err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
 		if (err < 0)
 			return err;

 		if (FIELD_GET(PCF8523_CONTROL3_PM, value) == PCF8523_PM_STANDBY) {
 			err = regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL3,
 					   value & ~PCF8523_CONTROL3_PM);
 			if (err < 0)
 				return err;
 		}
 	}

 	rtc->ops = &pcf8523_rtc_ops;
 	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	rtc->range_max = RTC_TIMESTAMP_END_2099;
 	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features);
 	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);

 	if (client->irq > 0) {
 		unsigned long irqflags = IRQF_TRIGGER_LOW;

 		if (dev_fwnode(&client->dev))
 			irqflags = 0;

 		err = regmap_write(pcf8523->regmap, PCF8523_TMR_CLKOUT_CTRL, 0x38);
 		if (err < 0)
 			return err;

 		err = devm_request_threaded_irq(&client->dev, client->irq,
 						NULL, pcf8523_irq,
 						IRQF_SHARED | IRQF_ONESHOT | irqflags,
 						dev_name(&rtc->dev), pcf8523);
 		if (err)
 			return err;

 		dev_pm_set_wake_irq(&client->dev, client->irq);
 	}

 	wakeup_source = of_property_read_bool(client->dev.of_node, "wakeup-source");
 	if (client->irq > 0 || wakeup_source)
 		device_init_wakeup(&client->dev, true);

 	return devm_rtc_register_device(rtc);
 }

 static const struct i2c_device_id pcf8523_id[] = {
 	{ "pcf8523", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, pcf8523_id);

 static const struct of_device_id pcf8523_of_match[] = {
 	{ .compatible = "nxp,pcf8523" },
 	{ .compatible = "microcrystal,rv8523" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, pcf8523_of_match);

 static struct i2c_driver pcf8523_driver = {
 	.driver = {
 		.name = "rtc-pcf8523",
 		.of_match_table = pcf8523_of_match,
 	},
 	.probe_new = pcf8523_probe,
 	.id_table = pcf8523_id,
 };
 module_i2c_driver(pcf8523_driver);

 MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
 MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2012 Avionic Design GmbH
	*/

	#include <linux/bcd.h>
	#include <linux/bitfield.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/regmap.h>
	#include <linux/rtc.h>
	#include <linux/of.h>
	#include <linux/pm_wakeirq.h>

	#define PCF8523_REG_CONTROL1 0x00
	#define PCF8523_CONTROL1_CAP_SEL BIT(7)
	#define PCF8523_CONTROL1_STOP BIT(5)
	#define PCF8523_CONTROL1_AIE BIT(1)

	#define PCF8523_REG_CONTROL2 0x01
	#define PCF8523_CONTROL2_AF BIT(3)

	#define PCF8523_REG_CONTROL3 0x02
	#define PCF8523_CONTROL3_PM GENMASK(7,5)
	#define PCF8523_PM_STANDBY 0x7
	#define PCF8523_CONTROL3_BLF BIT(2) /* battery low bit, read-only */
	#define PCF8523_CONTROL3_BSF BIT(3)

	#define PCF8523_REG_SECONDS 0x03
	#define PCF8523_SECONDS_OS BIT(7)

	#define PCF8523_REG_MINUTES 0x04
	#define PCF8523_REG_HOURS 0x05
	#define PCF8523_REG_DAYS 0x06
	#define PCF8523_REG_WEEKDAYS 0x07
	#define PCF8523_REG_MONTHS 0x08
	#define PCF8523_REG_YEARS 0x09

	#define PCF8523_REG_MINUTE_ALARM 0x0a
	#define PCF8523_REG_HOUR_ALARM 0x0b
	#define PCF8523_REG_DAY_ALARM 0x0c
	#define PCF8523_REG_WEEKDAY_ALARM 0x0d
	#define ALARM_DIS BIT(7)

	#define PCF8523_REG_OFFSET 0x0e
	#define PCF8523_OFFSET_MODE BIT(7)

	#define PCF8523_TMR_CLKOUT_CTRL 0x0f

	struct pcf8523 {
	struct rtc_device *rtc;
	struct regmap *regmap;
	};

	static int pcf8523_load_capacitance(struct pcf8523 pcf8523, struct device_node node)
	{
	u32 load, value = 0;

	load = 12500;
	of_property_read_u32(node, "quartz-load-femtofarads", &load);

	switch (load) {
	default:
	dev_warn(&pcf8523->rtc->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
	load);
	fallthrough;
	case 12500:
	value \|= PCF8523_CONTROL1_CAP_SEL;
	break;
	case 7000:
	break;
	}

	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
	PCF8523_CONTROL1_CAP_SEL, value);
	}

	static irqreturn_t pcf8523_irq(int irq, void *dev_id)
	{
	struct pcf8523 *pcf8523 = dev_id;
	u32 value;
	int err;

	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL2, &value);
	if (err < 0)
	return IRQ_HANDLED;

	if (value & PCF8523_CONTROL2_AF) {
	value &= ~PCF8523_CONTROL2_AF;
	regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL2, value);
	rtc_update_irq(pcf8523->rtc, 1, RTC_IRQF \| RTC_AF);

	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static int pcf8523_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	u8 regs[10];
	int err;

	err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_CONTROL1, regs,
	sizeof(regs));
	if (err < 0)
	return err;

	if ((regs[0] & PCF8523_CONTROL1_STOP) \|\| (regs[3] & PCF8523_SECONDS_OS))
	return -EINVAL;

	tm->tm_sec = bcd2bin(regs[3] & 0x7f);
	tm->tm_min = bcd2bin(regs[4] & 0x7f);
	tm->tm_hour = bcd2bin(regs[5] & 0x3f);
	tm->tm_mday = bcd2bin(regs[6] & 0x3f);
	tm->tm_wday = regs[7] & 0x7;
	tm->tm_mon = bcd2bin(regs[8] & 0x1f) - 1;
	tm->tm_year = bcd2bin(regs[9]) + 100;

	return 0;
	}

	static int pcf8523_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	u8 regs[7];
	int err;

	err = regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
	PCF8523_CONTROL1_STOP, PCF8523_CONTROL1_STOP);
	if (err < 0)
	return err;

	/* This will purposely overwrite PCF8523_SECONDS_OS */
	regs[0] = bin2bcd(tm->tm_sec);
	regs[1] = bin2bcd(tm->tm_min);
	regs[2] = bin2bcd(tm->tm_hour);
	regs[3] = bin2bcd(tm->tm_mday);
	regs[4] = tm->tm_wday;
	regs[5] = bin2bcd(tm->tm_mon + 1);
	regs[6] = bin2bcd(tm->tm_year - 100);

	err = regmap_bulk_write(pcf8523->regmap, PCF8523_REG_SECONDS, regs,
	sizeof(regs));
	if (err < 0) {
	/*
	* If the time cannot be set, restart the RTC anyway. Note
	* that errors are ignored if the RTC cannot be started so
	* that we have a chance to propagate the original error.
	*/
	regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
	PCF8523_CONTROL1_STOP, 0);
	return err;
	}

	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
	PCF8523_CONTROL1_STOP, 0);
	}

	static int pcf8523_rtc_read_alarm(struct device dev, struct rtc_wkalrm tm)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	u8 regs[4];
	u32 value;
	int err;

	err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_MINUTE_ALARM, regs,
	sizeof(regs));
	if (err < 0)
	return err;

	tm->time.tm_sec = 0;
	tm->time.tm_min = bcd2bin(regs[0] & 0x7F);
	tm->time.tm_hour = bcd2bin(regs[1] & 0x3F);
	tm->time.tm_mday = bcd2bin(regs[2] & 0x3F);
	tm->time.tm_wday = bcd2bin(regs[3] & 0x7);

	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL1, &value);
	if (err < 0)
	return err;
	tm->enabled = !!(value & PCF8523_CONTROL1_AIE);

	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL2, &value);
	if (err < 0)
	return err;
	tm->pending = !!(value & PCF8523_CONTROL2_AF);

	return 0;
	}

	static int pcf8523_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);

	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL1,
	PCF8523_CONTROL1_AIE, enabled ?
	PCF8523_CONTROL1_AIE : 0);
	}

	static int pcf8523_rtc_set_alarm(struct device dev, struct rtc_wkalrm tm)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	u8 regs[5];
	int err;

	err = pcf8523_irq_enable(dev, 0);
	if (err)
	return err;

	err = regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL2, 0);
	if (err < 0)
	return err;

	regs[0] = bin2bcd(tm->time.tm_min);
	regs[1] = bin2bcd(tm->time.tm_hour);
	regs[2] = bin2bcd(tm->time.tm_mday);
	regs[3] = ALARM_DIS;

	err = regmap_bulk_write(pcf8523->regmap, PCF8523_REG_MINUTE_ALARM, regs,
	sizeof(regs));
	if (err < 0)
	return err;

	if (tm->enabled)
	return pcf8523_irq_enable(dev, tm->enabled);

	return 0;
	}

	static int pcf8523_param_get(struct device dev, struct rtc_param param)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	int ret;
	u32 value;

	switch(param->param) {

	case RTC_PARAM_BACKUP_SWITCH_MODE:
	ret = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
	if (ret < 0)
	return ret;

	value = FIELD_GET(PCF8523_CONTROL3_PM, value);

	switch(value) {
	case 0x0:
	case 0x4:
	param->uvalue = RTC_BSM_LEVEL;
	break;
	case 0x1:
	case 0x5:
	param->uvalue = RTC_BSM_DIRECT;
	break;
	case PCF8523_PM_STANDBY:
	param->uvalue = RTC_BSM_STANDBY;
	break;
	default:
	param->uvalue = RTC_BSM_DISABLED;
	}

	break;

	default:
	return -EINVAL;
	}

	return 0;
	}

	static int pcf8523_param_set(struct device dev, struct rtc_param param)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	u8 mode;

	switch(param->param) {
	case RTC_PARAM_BACKUP_SWITCH_MODE:
	switch (param->uvalue) {
	case RTC_BSM_DISABLED:
	mode = 0x2;
	break;
	case RTC_BSM_DIRECT:
	mode = 0x1;
	break;
	case RTC_BSM_LEVEL:
	mode = 0x0;
	break;
	case RTC_BSM_STANDBY:
	mode = PCF8523_PM_STANDBY;
	break;
	default:
	return -EINVAL;
	}

	return regmap_update_bits(pcf8523->regmap, PCF8523_REG_CONTROL3,
	PCF8523_CONTROL3_PM,
	FIELD_PREP(PCF8523_CONTROL3_PM, mode));

	break;

	default:
	return -EINVAL;
	}

	return 0;
	}

	static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	unsigned int flags = 0;
	u32 value;
	int ret;

	switch (cmd) {
	case RTC_VL_READ:
	ret = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
	if (ret < 0)
	return ret;

	if (value & PCF8523_CONTROL3_BLF)
	flags \|= RTC_VL_BACKUP_LOW;

	ret = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS, &value);
	if (ret < 0)
	return ret;

	if (value & PCF8523_SECONDS_OS)
	flags \|= RTC_VL_DATA_INVALID;

	return put_user(flags, (unsigned int __user *)arg);

	default:
	return -ENOIOCTLCMD;
	}
	}

	static int pcf8523_rtc_read_offset(struct device dev, long offset)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	int err;
	u32 value;
	s8 val;

	err = regmap_read(pcf8523->regmap, PCF8523_REG_OFFSET, &value);
	if (err < 0)
	return err;

	/* sign extend the 7-bit offset value */
	val = value << 1;
	offset = (value & PCF8523_OFFSET_MODE ? 4069 : 4340) (val >> 1);

	return 0;
	}

	static int pcf8523_rtc_set_offset(struct device *dev, long offset)
	{
	struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
	long reg_m0, reg_m1;
	u32 value;

	reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
	reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);

	if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
	value = reg_m0 & 0x7f;
	else
	value = (reg_m1 & 0x7f) \| PCF8523_OFFSET_MODE;

	return regmap_write(pcf8523->regmap, PCF8523_REG_OFFSET, value);
	}

	static const struct rtc_class_ops pcf8523_rtc_ops = {
	.read_time = pcf8523_rtc_read_time,
	.set_time = pcf8523_rtc_set_time,
	.read_alarm = pcf8523_rtc_read_alarm,
	.set_alarm = pcf8523_rtc_set_alarm,
	.alarm_irq_enable = pcf8523_irq_enable,
	.ioctl = pcf8523_rtc_ioctl,
	.read_offset = pcf8523_rtc_read_offset,
	.set_offset = pcf8523_rtc_set_offset,
	.param_get = pcf8523_param_get,
	.param_set = pcf8523_param_set,
	};

	static const struct regmap_config regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = 0x13,
	};

	static int pcf8523_probe(struct i2c_client *client)
	{
	struct pcf8523 *pcf8523;
	struct rtc_device *rtc;
	bool wakeup_source = false;
	u32 value;
	int err;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -ENODEV;

	pcf8523 = devm_kzalloc(&client->dev, sizeof(struct pcf8523), GFP_KERNEL);
	if (!pcf8523)
	return -ENOMEM;

	pcf8523->regmap = devm_regmap_init_i2c(client, &regmap_config);
	if (IS_ERR(pcf8523->regmap))
	return PTR_ERR(pcf8523->regmap);

	i2c_set_clientdata(client, pcf8523);

	rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);
	pcf8523->rtc = rtc;

	err = pcf8523_load_capacitance(pcf8523, client->dev.of_node);
	if (err < 0)
	dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
	err);

	err = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS, &value);
	if (err < 0)
	return err;

	if (value & PCF8523_SECONDS_OS) {
	err = regmap_read(pcf8523->regmap, PCF8523_REG_CONTROL3, &value);
	if (err < 0)
	return err;

	if (FIELD_GET(PCF8523_CONTROL3_PM, value) == PCF8523_PM_STANDBY) {
	err = regmap_write(pcf8523->regmap, PCF8523_REG_CONTROL3,
	value & ~PCF8523_CONTROL3_PM);
	if (err < 0)
	return err;
	}
	}

	rtc->ops = &pcf8523_rtc_ops;
	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
	rtc->range_max = RTC_TIMESTAMP_END_2099;
	set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features);
	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);

	if (client->irq > 0) {
	unsigned long irqflags = IRQF_TRIGGER_LOW;

	if (dev_fwnode(&client->dev))
	irqflags = 0;

	err = regmap_write(pcf8523->regmap, PCF8523_TMR_CLKOUT_CTRL, 0x38);
	if (err < 0)
	return err;

	err = devm_request_threaded_irq(&client->dev, client->irq,
	NULL, pcf8523_irq,
	IRQF_SHARED \| IRQF_ONESHOT \| irqflags,
	dev_name(&rtc->dev), pcf8523);
	if (err)
	return err;

	dev_pm_set_wake_irq(&client->dev, client->irq);
	}

	wakeup_source = of_property_read_bool(client->dev.of_node, "wakeup-source");
	if (client->irq > 0 \|\| wakeup_source)
	device_init_wakeup(&client->dev, true);

	return devm_rtc_register_device(rtc);
	}

	static const struct i2c_device_id pcf8523_id[] = {
	{ "pcf8523", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, pcf8523_id);

	static const struct of_device_id pcf8523_of_match[] = {
	{ .compatible = "nxp,pcf8523" },
	{ .compatible = "microcrystal,rv8523" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, pcf8523_of_match);

	static struct i2c_driver pcf8523_driver = {
	.driver = {
	.name = "rtc-pcf8523",
	.of_match_table = pcf8523_of_match,
	},
	.probe_new = pcf8523_probe,
	.id_table = pcf8523_id,
	};
	module_i2c_driver(pcf8523_driver);

	MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
	MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
	MODULE_LICENSE("GPL v2");