drivers/rtc/rtc-ds3232.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * RTC client/driver for the Maxim/Dallas DS3232/DS3234 Real-Time Clock
  *
  * Copyright (C) 2009-2011 Freescale Semiconductor.
  * Author: Jack Lan <jack.lan@freescale.com>
  * Copyright (C) 2008 MIMOMax Wireless Ltd.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/i2c.h>
 #include <linux/spi/spi.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
 #include <linux/slab.h>
 #include <linux/regmap.h>
 #include <linux/hwmon.h>

 #define DS3232_REG_SECONDS      0x00
 #define DS3232_REG_MINUTES      0x01
 #define DS3232_REG_HOURS        0x02
 #define DS3232_REG_AMPM         0x02
 #define DS3232_REG_DAY          0x03
 #define DS3232_REG_DATE         0x04
 #define DS3232_REG_MONTH        0x05
 #define DS3232_REG_CENTURY      0x05
 #define DS3232_REG_YEAR         0x06
 #define DS3232_REG_ALARM1       0x07       /* Alarm 1 BASE */
 #define DS3232_REG_ALARM2       0x0B       /* Alarm 2 BASE */
 #define DS3232_REG_CR           0x0E       /* Control register */
 #       define DS3232_REG_CR_nEOSC   0x80
 #       define DS3232_REG_CR_INTCN   0x04
 #       define DS3232_REG_CR_A2IE    0x02
 #       define DS3232_REG_CR_A1IE    0x01

 #define DS3232_REG_SR           0x0F       /* control/status register */
 #       define DS3232_REG_SR_OSF     0x80
 #       define DS3232_REG_SR_BSY     0x04
 #       define DS3232_REG_SR_A2F     0x02
 #       define DS3232_REG_SR_A1F     0x01

 #define DS3232_REG_TEMPERATURE	0x11
 #define DS3232_REG_SRAM_START   0x14
 #define DS3232_REG_SRAM_END     0xFF

 #define DS3232_REG_SRAM_SIZE    236

 struct ds3232 {
 	struct device *dev;
 	struct regmap *regmap;
 	int irq;
 	struct rtc_device *rtc;

 	bool suspended;
 };

 static int ds3232_check_rtc_status(struct device *dev)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int ret = 0;
 	int control, stat;

 	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
 	if (ret)
 		return ret;

 	if (stat & DS3232_REG_SR_OSF)
 		dev_warn(dev,
 				"oscillator discontinuity flagged, "
 				"time unreliable\n");

 	stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);

 	ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
 	if (ret)
 		return ret;

 	/* If the alarm is pending, clear it before requesting
 	 * the interrupt, so an interrupt event isn't reported
 	 * before everything is initialized.
 	 */

 	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
 	if (ret)
 		return ret;

 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 	control |= DS3232_REG_CR_INTCN;

 	return regmap_write(ds3232->regmap, DS3232_REG_CR, control);
 }

 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int ret;
 	u8 buf[7];
 	unsigned int year, month, day, hour, minute, second;
 	unsigned int week, twelve_hr, am_pm;
 	unsigned int century, add_century = 0;

 	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
 	if (ret)
 		return ret;

 	second = buf[0];
 	minute = buf[1];
 	hour = buf[2];
 	week = buf[3];
 	day = buf[4];
 	month = buf[5];
 	year = buf[6];

 	/* Extract additional information for AM/PM and century */

 	twelve_hr = hour & 0x40;
 	am_pm = hour & 0x20;
 	century = month & 0x80;

 	/* Write to rtc_time structure */

 	time->tm_sec = bcd2bin(second);
 	time->tm_min = bcd2bin(minute);
 	if (twelve_hr) {
 		/* Convert to 24 hr */
 		if (am_pm)
 			time->tm_hour = bcd2bin(hour & 0x1F) + 12;
 		else
 			time->tm_hour = bcd2bin(hour & 0x1F);
 	} else {
 		time->tm_hour = bcd2bin(hour);
 	}

 	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
 	time->tm_wday = bcd2bin(week) - 1;
 	time->tm_mday = bcd2bin(day);
 	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
 	time->tm_mon = bcd2bin(month & 0x7F) - 1;
 	if (century)
 		add_century = 100;

 	time->tm_year = bcd2bin(year) + add_century;

 	return 0;
 }

 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	u8 buf[7];

 	/* Extract time from rtc_time and load into ds3232*/

 	buf[0] = bin2bcd(time->tm_sec);
 	buf[1] = bin2bcd(time->tm_min);
 	buf[2] = bin2bcd(time->tm_hour);
 	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
 	buf[3] = bin2bcd(time->tm_wday + 1);
 	buf[4] = bin2bcd(time->tm_mday); /* Date */
 	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
 	buf[5] = bin2bcd(time->tm_mon + 1);
 	if (time->tm_year >= 100) {
 		buf[5] |= 0x80;
 		buf[6] = bin2bcd(time->tm_year - 100);
 	} else {
 		buf[6] = bin2bcd(time->tm_year);
 	}

 	return regmap_bulk_write(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
 }

 /*
  * DS3232 has two alarm, we only use alarm1
  * According to linux specification, only support one-shot alarm
  * no periodic alarm mode
  */
 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int control, stat;
 	int ret;
 	u8 buf[4];

 	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
 	if (ret)
 		goto out;
 	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
 	if (ret)
 		goto out;
 	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
 	if (ret)
 		goto out;

 	alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
 	alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
 	alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
 	alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);

 	alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
 	alarm->pending = !!(stat & DS3232_REG_SR_A1F);

 	ret = 0;
 out:
 	return ret;
 }

 /*
  * linux rtc-module does not support wday alarm
  * and only 24h time mode supported indeed
  */
 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int control, stat;
 	int ret;
 	u8 buf[4];

 	if (ds3232->irq <= 0)
 		return -EINVAL;

 	buf[0] = bin2bcd(alarm->time.tm_sec);
 	buf[1] = bin2bcd(alarm->time.tm_min);
 	buf[2] = bin2bcd(alarm->time.tm_hour);
 	buf[3] = bin2bcd(alarm->time.tm_mday);

 	/* clear alarm interrupt enable bit */
 	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
 	if (ret)
 		goto out;
 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 	ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
 	if (ret)
 		goto out;

 	/* clear any pending alarm flag */
 	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
 	if (ret)
 		goto out;
 	stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
 	ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
 	if (ret)
 		goto out;

 	ret = regmap_bulk_write(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
 	if (ret)
 		goto out;

 	if (alarm->enabled) {
 		control |= DS3232_REG_CR_A1IE;
 		ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
 	}
 out:
 	return ret;
 }

 static int ds3232_update_alarm(struct device *dev, unsigned int enabled)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int control;
 	int ret;

 	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
 	if (ret)
 		return ret;

 	if (enabled)
 		/* enable alarm1 interrupt */
 		control |= DS3232_REG_CR_A1IE;
 	else
 		/* disable alarm1 interrupt */
 		control &= ~(DS3232_REG_CR_A1IE);
 	ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);

 	return ret;
 }

 /*
  * Temperature sensor support for ds3232/ds3234 devices.
  * A user-initiated temperature conversion is not started by this function,
  * so the temperature is updated once every 64 seconds.
  */
 static int ds3232_hwmon_read_temp(struct device *dev, long int *mC)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	u8 temp_buf[2];
 	s16 temp;
 	int ret;

 	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_TEMPERATURE, temp_buf,
 			       sizeof(temp_buf));
 	if (ret < 0)
 		return ret;

 	/*
 	 * Temperature is represented as a 10-bit code with a resolution of
 	 * 0.25 degree celsius and encoded in two's complement format.
 	 */
 	temp = (temp_buf[0] << 8) | temp_buf[1];
 	temp >>= 6;
 	*mC = temp * 250;

 	return 0;
 }

 static umode_t ds3232_hwmon_is_visible(const void *data,
 				       enum hwmon_sensor_types type,
 				       u32 attr, int channel)
 {
 	if (type != hwmon_temp)
 		return 0;

 	switch (attr) {
 	case hwmon_temp_input:
 		return 0444;
 	default:
 		return 0;
 	}
 }

 static int ds3232_hwmon_read(struct device *dev,
 			     enum hwmon_sensor_types type,
 			     u32 attr, int channel, long *temp)
 {
 	int err;

 	switch (attr) {
 	case hwmon_temp_input:
 		err = ds3232_hwmon_read_temp(dev, temp);
 		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;
 	}

 	return err;
 }

 static u32 ds3232_hwmon_chip_config[] = {
 	HWMON_C_REGISTER_TZ,
 	0
 };

 static const struct hwmon_channel_info ds3232_hwmon_chip = {
 	.type = hwmon_chip,
 	.config = ds3232_hwmon_chip_config,
 };

 static u32 ds3232_hwmon_temp_config[] = {
 	HWMON_T_INPUT,
 	0
 };

 static const struct hwmon_channel_info ds3232_hwmon_temp = {
 	.type = hwmon_temp,
 	.config = ds3232_hwmon_temp_config,
 };

 static const struct hwmon_channel_info *ds3232_hwmon_info[] = {
 	&ds3232_hwmon_chip,
 	&ds3232_hwmon_temp,
 	NULL
 };

 static const struct hwmon_ops ds3232_hwmon_hwmon_ops = {
 	.is_visible = ds3232_hwmon_is_visible,
 	.read = ds3232_hwmon_read,
 };

 static const struct hwmon_chip_info ds3232_hwmon_chip_info = {
 	.ops = &ds3232_hwmon_hwmon_ops,
 	.info = ds3232_hwmon_info,
 };

 static void ds3232_hwmon_register(struct device *dev, const char *name)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	struct device *hwmon_dev;

 	if (!IS_ENABLED(CONFIG_RTC_DRV_DS3232_HWMON))
 		return;

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, name, ds3232,
 							&ds3232_hwmon_chip_info,
 							NULL);
 	if (IS_ERR(hwmon_dev)) {
 		dev_err(dev, "unable to register hwmon device %ld\n",
 			PTR_ERR(hwmon_dev));
 	}
 }

 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);

 	if (ds3232->irq <= 0)
 		return -EINVAL;

 	return ds3232_update_alarm(dev, enabled);
 }

 static irqreturn_t ds3232_irq(int irq, void *dev_id)
 {
 	struct device *dev = dev_id;
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
 	int ret;
 	int stat, control;

 	rtc_lock(ds3232->rtc);

 	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
 	if (ret)
 		goto unlock;

 	if (stat & DS3232_REG_SR_A1F) {
 		ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
 		if (ret) {
 			dev_warn(ds3232->dev,
 				 "Read Control Register error %d\n", ret);
 		} else {
 			/* disable alarm1 interrupt */
 			control &= ~(DS3232_REG_CR_A1IE);
 			ret = regmap_write(ds3232->regmap, DS3232_REG_CR,
 					   control);
 			if (ret) {
 				dev_warn(ds3232->dev,
 					 "Write Control Register error %d\n",
 					 ret);
 				goto unlock;
 			}

 			/* clear the alarm pend flag */
 			stat &= ~DS3232_REG_SR_A1F;
 			ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
 			if (ret) {
 				dev_warn(ds3232->dev,
 					 "Write Status Register error %d\n",
 					 ret);
 				goto unlock;
 			}

 			rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
 		}
 	}

 unlock:
 	rtc_unlock(ds3232->rtc);

 	return IRQ_HANDLED;
 }

 static const struct rtc_class_ops ds3232_rtc_ops = {
 	.read_time = ds3232_read_time,
 	.set_time = ds3232_set_time,
 	.read_alarm = ds3232_read_alarm,
 	.set_alarm = ds3232_set_alarm,
 	.alarm_irq_enable = ds3232_alarm_irq_enable,
 };

 static int ds3232_nvmem_read(void *priv, unsigned int offset, void *val,
 			     size_t bytes)
 {
 	struct regmap *ds3232_regmap = (struct regmap *)priv;

 	return regmap_bulk_read(ds3232_regmap, DS3232_REG_SRAM_START + offset,
 				val, bytes);
 }

 static int ds3232_nvmem_write(void *priv, unsigned int offset, void *val,
 			      size_t bytes)
 {
 	struct regmap *ds3232_regmap = (struct regmap *)priv;

 	return regmap_bulk_write(ds3232_regmap, DS3232_REG_SRAM_START + offset,
 				 val, bytes);
 }

 static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
 			const char *name)
 {
 	struct ds3232 *ds3232;
 	int ret;
 	struct nvmem_config nvmem_cfg = {
 		.name = "ds3232_sram",
 		.stride = 1,
 		.size = DS3232_REG_SRAM_SIZE,
 		.word_size = 1,
 		.reg_read = ds3232_nvmem_read,
 		.reg_write = ds3232_nvmem_write,
 		.priv = regmap,
 		.type = NVMEM_TYPE_BATTERY_BACKED
 	};

 	ds3232 = devm_kzalloc(dev, sizeof(*ds3232), GFP_KERNEL);
 	if (!ds3232)
 		return -ENOMEM;

 	ds3232->regmap = regmap;
 	ds3232->irq = irq;
 	ds3232->dev = dev;
 	dev_set_drvdata(dev, ds3232);

 	ret = ds3232_check_rtc_status(dev);
 	if (ret)
 		return ret;

 	if (ds3232->irq > 0)
 		device_init_wakeup(dev, 1);

 	ds3232_hwmon_register(dev, name);

 	ds3232->rtc = devm_rtc_device_register(dev, name, &ds3232_rtc_ops,
 						THIS_MODULE);
 	if (IS_ERR(ds3232->rtc))
 		return PTR_ERR(ds3232->rtc);

 	ret = devm_rtc_nvmem_register(ds3232->rtc, &nvmem_cfg);
 	if(ret)
 		return ret;

 	if (ds3232->irq > 0) {
 		ret = devm_request_threaded_irq(dev, ds3232->irq, NULL,
 						ds3232_irq,
 						IRQF_SHARED | IRQF_ONESHOT,
 						name, dev);
 		if (ret) {
 			device_set_wakeup_capable(dev, 0);
 			ds3232->irq = 0;
 			dev_err(dev, "unable to request IRQ\n");
 		}
 	}

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int ds3232_suspend(struct device *dev)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev)) {
 		if (enable_irq_wake(ds3232->irq))
 			dev_warn_once(dev, "Cannot set wakeup source\n");
 	}

 	return 0;
 }

 static int ds3232_resume(struct device *dev)
 {
 	struct ds3232 *ds3232 = dev_get_drvdata(dev);

 	if (device_may_wakeup(dev))
 		disable_irq_wake(ds3232->irq);

 	return 0;
 }
 #endif

 static const struct dev_pm_ops ds3232_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
 };

 #if IS_ENABLED(CONFIG_I2C)

 static int ds3232_i2c_probe(struct i2c_client *client)
 {
 	struct regmap *regmap;
 	static const struct regmap_config config = {
 		.reg_bits = 8,
 		.val_bits = 8,
 		.max_register = DS3232_REG_SRAM_END,
 	};

 	regmap = devm_regmap_init_i2c(client, &config);
 	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
 			__func__, PTR_ERR(regmap));
 		return PTR_ERR(regmap);
 	}

 	return ds3232_probe(&client->dev, regmap, client->irq, client->name);
 }

 static const struct i2c_device_id ds3232_id[] = {
 	{ "ds3232", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ds3232_id);

 static const  __maybe_unused struct of_device_id ds3232_of_match[] = {
 	{ .compatible = "dallas,ds3232" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ds3232_of_match);

 static struct i2c_driver ds3232_driver = {
 	.driver = {
 		.name = "rtc-ds3232",
 		.of_match_table = of_match_ptr(ds3232_of_match),
 		.pm	= &ds3232_pm_ops,
 	},
 	.probe_new = ds3232_i2c_probe,
 	.id_table = ds3232_id,
 };

 static int ds3232_register_driver(void)
 {
 	return i2c_add_driver(&ds3232_driver);
 }

 static void ds3232_unregister_driver(void)
 {
 	i2c_del_driver(&ds3232_driver);
 }

 #else

 static int ds3232_register_driver(void)
 {
 	return 0;
 }

 static void ds3232_unregister_driver(void)
 {
 }

 #endif

 #if IS_ENABLED(CONFIG_SPI_MASTER)

 static int ds3234_probe(struct spi_device *spi)
 {
 	int res;
 	unsigned int tmp;
 	static const struct regmap_config config = {
 		.reg_bits = 8,
 		.val_bits = 8,
 		.max_register = DS3232_REG_SRAM_END,
 		.write_flag_mask = 0x80,
 	};
 	struct regmap *regmap;

 	regmap = devm_regmap_init_spi(spi, &config);
 	if (IS_ERR(regmap)) {
 		dev_err(&spi->dev, "%s: regmap allocation failed: %ld\n",
 			__func__, PTR_ERR(regmap));
 		return PTR_ERR(regmap);
 	}

 	spi->mode = SPI_MODE_3;
 	spi->bits_per_word = 8;
 	spi_setup(spi);

 	res = regmap_read(regmap, DS3232_REG_SECONDS, &tmp);
 	if (res)
 		return res;

 	/* Control settings
 	 *
 	 * CONTROL_REG
 	 * BIT 7	6	5	4	3	2	1	0
 	 *     EOSC	BBSQW	CONV	RS2	RS1	INTCN	A2IE	A1IE
 	 *
 	 *     0	0	0	1	1	1	0	0
 	 *
 	 * CONTROL_STAT_REG
 	 * BIT 7	6	5	4	3	2	1	0
 	 *     OSF	BB32kHz	CRATE1	CRATE0	EN32kHz	BSY	A2F	A1F
 	 *
 	 *     1	0	0	0	1	0	0	0
 	 */
 	res = regmap_read(regmap, DS3232_REG_CR, &tmp);
 	if (res)
 		return res;
 	res = regmap_write(regmap, DS3232_REG_CR, tmp & 0x1c);
 	if (res)
 		return res;

 	res = regmap_read(regmap, DS3232_REG_SR, &tmp);
 	if (res)
 		return res;
 	res = regmap_write(regmap, DS3232_REG_SR, tmp & 0x88);
 	if (res)
 		return res;

 	/* Print our settings */
 	res = regmap_read(regmap, DS3232_REG_CR, &tmp);
 	if (res)
 		return res;
 	dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);

 	res = regmap_read(regmap, DS3232_REG_SR, &tmp);
 	if (res)
 		return res;
 	dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);

 	return ds3232_probe(&spi->dev, regmap, spi->irq, "ds3234");
 }

 static struct spi_driver ds3234_driver = {
 	.driver = {
 		.name	 = "ds3234",
 	},
 	.probe	 = ds3234_probe,
 };

 static int ds3234_register_driver(void)
 {
 	return spi_register_driver(&ds3234_driver);
 }

 static void ds3234_unregister_driver(void)
 {
 	spi_unregister_driver(&ds3234_driver);
 }

 #else

 static int ds3234_register_driver(void)
 {
 	return 0;
 }

 static void ds3234_unregister_driver(void)
 {
 }

 #endif

 static int __init ds323x_init(void)
 {
 	int ret;

 	ret = ds3232_register_driver();
 	if (ret) {
 		pr_err("Failed to register ds3232 driver: %d\n", ret);
 		return ret;
 	}

 	ret = ds3234_register_driver();
 	if (ret) {
 		pr_err("Failed to register ds3234 driver: %d\n", ret);
 		ds3232_unregister_driver();
 	}

 	return ret;
 }
 module_init(ds323x_init)

 static void __exit ds323x_exit(void)
 {
 	ds3234_unregister_driver();
 	ds3232_unregister_driver();
 }
 module_exit(ds323x_exit)

 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
 MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
 MODULE_DESCRIPTION("Maxim/Dallas DS3232/DS3234 RTC Driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("spi:ds3234");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* RTC client/driver for the Maxim/Dallas DS3232/DS3234 Real-Time Clock
	*
	* Copyright (C) 2009-2011 Freescale Semiconductor.
	* Author: Jack Lan <jack.lan@freescale.com>
	* Copyright (C) 2008 MIMOMax Wireless Ltd.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/i2c.h>
	#include <linux/spi/spi.h>
	#include <linux/rtc.h>
	#include <linux/bcd.h>
	#include <linux/slab.h>
	#include <linux/regmap.h>
	#include <linux/hwmon.h>

	#define DS3232_REG_SECONDS 0x00
	#define DS3232_REG_MINUTES 0x01
	#define DS3232_REG_HOURS 0x02
	#define DS3232_REG_AMPM 0x02
	#define DS3232_REG_DAY 0x03
	#define DS3232_REG_DATE 0x04
	#define DS3232_REG_MONTH 0x05
	#define DS3232_REG_CENTURY 0x05
	#define DS3232_REG_YEAR 0x06
	#define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */
	#define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */
	#define DS3232_REG_CR 0x0E /* Control register */
	# define DS3232_REG_CR_nEOSC 0x80
	# define DS3232_REG_CR_INTCN 0x04
	# define DS3232_REG_CR_A2IE 0x02
	# define DS3232_REG_CR_A1IE 0x01

	#define DS3232_REG_SR 0x0F /* control/status register */
	# define DS3232_REG_SR_OSF 0x80
	# define DS3232_REG_SR_BSY 0x04
	# define DS3232_REG_SR_A2F 0x02
	# define DS3232_REG_SR_A1F 0x01

	#define DS3232_REG_TEMPERATURE 0x11
	#define DS3232_REG_SRAM_START 0x14
	#define DS3232_REG_SRAM_END 0xFF

	#define DS3232_REG_SRAM_SIZE 236

	struct ds3232 {
	struct device *dev;
	struct regmap *regmap;
	int irq;
	struct rtc_device *rtc;

	bool suspended;
	};

	static int ds3232_check_rtc_status(struct device *dev)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int ret = 0;
	int control, stat;

	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
	if (ret)
	return ret;

	if (stat & DS3232_REG_SR_OSF)
	dev_warn(dev,
	"oscillator discontinuity flagged, "
	"time unreliable\n");

	stat &= ~(DS3232_REG_SR_OSF \| DS3232_REG_SR_A1F \| DS3232_REG_SR_A2F);

	ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
	if (ret)
	return ret;

	/* If the alarm is pending, clear it before requesting
	* the interrupt, so an interrupt event isn't reported
	* before everything is initialized.
	*/

	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
	if (ret)
	return ret;

	control &= ~(DS3232_REG_CR_A1IE \| DS3232_REG_CR_A2IE);
	control \|= DS3232_REG_CR_INTCN;

	return regmap_write(ds3232->regmap, DS3232_REG_CR, control);
	}

	static int ds3232_read_time(struct device dev, struct rtc_time time)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int ret;
	u8 buf[7];
	unsigned int year, month, day, hour, minute, second;
	unsigned int week, twelve_hr, am_pm;
	unsigned int century, add_century = 0;

	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
	if (ret)
	return ret;

	second = buf[0];
	minute = buf[1];
	hour = buf[2];
	week = buf[3];
	day = buf[4];
	month = buf[5];
	year = buf[6];

	/* Extract additional information for AM/PM and century */

	twelve_hr = hour & 0x40;
	am_pm = hour & 0x20;
	century = month & 0x80;

	/* Write to rtc_time structure */

	time->tm_sec = bcd2bin(second);
	time->tm_min = bcd2bin(minute);
	if (twelve_hr) {
	/* Convert to 24 hr */
	if (am_pm)
	time->tm_hour = bcd2bin(hour & 0x1F) + 12;
	else
	time->tm_hour = bcd2bin(hour & 0x1F);
	} else {
	time->tm_hour = bcd2bin(hour);
	}

	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
	time->tm_wday = bcd2bin(week) - 1;
	time->tm_mday = bcd2bin(day);
	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
	time->tm_mon = bcd2bin(month & 0x7F) - 1;
	if (century)
	add_century = 100;

	time->tm_year = bcd2bin(year) + add_century;

	return 0;
	}

	static int ds3232_set_time(struct device dev, struct rtc_time time)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	u8 buf[7];

	/* Extract time from rtc_time and load into ds3232*/

	buf[0] = bin2bcd(time->tm_sec);
	buf[1] = bin2bcd(time->tm_min);
	buf[2] = bin2bcd(time->tm_hour);
	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
	buf[3] = bin2bcd(time->tm_wday + 1);
	buf[4] = bin2bcd(time->tm_mday); /* Date */
	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
	buf[5] = bin2bcd(time->tm_mon + 1);
	if (time->tm_year >= 100) {
	buf[5] \|= 0x80;
	buf[6] = bin2bcd(time->tm_year - 100);
	} else {
	buf[6] = bin2bcd(time->tm_year);
	}

	return regmap_bulk_write(ds3232->regmap, DS3232_REG_SECONDS, buf, 7);
	}

	/*
	* DS3232 has two alarm, we only use alarm1
	* According to linux specification, only support one-shot alarm
	* no periodic alarm mode
	*/
	static int ds3232_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int control, stat;
	int ret;
	u8 buf[4];

	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
	if (ret)
	goto out;
	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
	if (ret)
	goto out;
	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
	if (ret)
	goto out;

	alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
	alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
	alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
	alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);

	alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
	alarm->pending = !!(stat & DS3232_REG_SR_A1F);

	ret = 0;
	out:
	return ret;
	}

	/*
	* linux rtc-module does not support wday alarm
	* and only 24h time mode supported indeed
	*/
	static int ds3232_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int control, stat;
	int ret;
	u8 buf[4];

	if (ds3232->irq <= 0)
	return -EINVAL;

	buf[0] = bin2bcd(alarm->time.tm_sec);
	buf[1] = bin2bcd(alarm->time.tm_min);
	buf[2] = bin2bcd(alarm->time.tm_hour);
	buf[3] = bin2bcd(alarm->time.tm_mday);

	/* clear alarm interrupt enable bit */
	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
	if (ret)
	goto out;
	control &= ~(DS3232_REG_CR_A1IE \| DS3232_REG_CR_A2IE);
	ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
	if (ret)
	goto out;

	/* clear any pending alarm flag */
	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
	if (ret)
	goto out;
	stat &= ~(DS3232_REG_SR_A1F \| DS3232_REG_SR_A2F);
	ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
	if (ret)
	goto out;

	ret = regmap_bulk_write(ds3232->regmap, DS3232_REG_ALARM1, buf, 4);
	if (ret)
	goto out;

	if (alarm->enabled) {
	control \|= DS3232_REG_CR_A1IE;
	ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);
	}
	out:
	return ret;
	}

	static int ds3232_update_alarm(struct device *dev, unsigned int enabled)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int control;
	int ret;

	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
	if (ret)
	return ret;

	if (enabled)
	/* enable alarm1 interrupt */
	control \|= DS3232_REG_CR_A1IE;
	else
	/* disable alarm1 interrupt */
	control &= ~(DS3232_REG_CR_A1IE);
	ret = regmap_write(ds3232->regmap, DS3232_REG_CR, control);

	return ret;
	}

	/*
	* Temperature sensor support for ds3232/ds3234 devices.
	* A user-initiated temperature conversion is not started by this function,
	* so the temperature is updated once every 64 seconds.
	*/
	static int ds3232_hwmon_read_temp(struct device dev, long int mC)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	u8 temp_buf[2];
	s16 temp;
	int ret;

	ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_TEMPERATURE, temp_buf,
	sizeof(temp_buf));
	if (ret < 0)
	return ret;

	/*
	* Temperature is represented as a 10-bit code with a resolution of
	* 0.25 degree celsius and encoded in two's complement format.
	*/
	temp = (temp_buf[0] << 8) \| temp_buf[1];
	temp >>= 6;
	mC = temp 250;

	return 0;
	}

	static umode_t ds3232_hwmon_is_visible(const void *data,
	enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	if (type != hwmon_temp)
	return 0;

	switch (attr) {
	case hwmon_temp_input:
	return 0444;
	default:
	return 0;
	}
	}

	static int ds3232_hwmon_read(struct device *dev,
	enum hwmon_sensor_types type,
	u32 attr, int channel, long *temp)
	{
	int err;

	switch (attr) {
	case hwmon_temp_input:
	err = ds3232_hwmon_read_temp(dev, temp);
	break;
	default:
	err = -EOPNOTSUPP;
	break;
	}

	return err;
	}

	static u32 ds3232_hwmon_chip_config[] = {
	HWMON_C_REGISTER_TZ,
	0
	};

	static const struct hwmon_channel_info ds3232_hwmon_chip = {
	.type = hwmon_chip,
	.config = ds3232_hwmon_chip_config,
	};

	static u32 ds3232_hwmon_temp_config[] = {
	HWMON_T_INPUT,
	0
	};

	static const struct hwmon_channel_info ds3232_hwmon_temp = {
	.type = hwmon_temp,
	.config = ds3232_hwmon_temp_config,
	};

	static const struct hwmon_channel_info *ds3232_hwmon_info[] = {
	&ds3232_hwmon_chip,
	&ds3232_hwmon_temp,
	NULL
	};

	static const struct hwmon_ops ds3232_hwmon_hwmon_ops = {
	.is_visible = ds3232_hwmon_is_visible,
	.read = ds3232_hwmon_read,
	};

	static const struct hwmon_chip_info ds3232_hwmon_chip_info = {
	.ops = &ds3232_hwmon_hwmon_ops,
	.info = ds3232_hwmon_info,
	};

	static void ds3232_hwmon_register(struct device dev, const char name)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	struct device *hwmon_dev;

	if (!IS_ENABLED(CONFIG_RTC_DRV_DS3232_HWMON))
	return;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, name, ds3232,
	&ds3232_hwmon_chip_info,
	NULL);
	if (IS_ERR(hwmon_dev)) {
	dev_err(dev, "unable to register hwmon device %ld\n",
	PTR_ERR(hwmon_dev));
	}
	}

	static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);

	if (ds3232->irq <= 0)
	return -EINVAL;

	return ds3232_update_alarm(dev, enabled);
	}

	static irqreturn_t ds3232_irq(int irq, void *dev_id)
	{
	struct device *dev = dev_id;
	struct ds3232 *ds3232 = dev_get_drvdata(dev);
	int ret;
	int stat, control;

	rtc_lock(ds3232->rtc);

	ret = regmap_read(ds3232->regmap, DS3232_REG_SR, &stat);
	if (ret)
	goto unlock;

	if (stat & DS3232_REG_SR_A1F) {
	ret = regmap_read(ds3232->regmap, DS3232_REG_CR, &control);
	if (ret) {
	dev_warn(ds3232->dev,
	"Read Control Register error %d\n", ret);
	} else {
	/* disable alarm1 interrupt */
	control &= ~(DS3232_REG_CR_A1IE);
	ret = regmap_write(ds3232->regmap, DS3232_REG_CR,
	control);
	if (ret) {
	dev_warn(ds3232->dev,
	"Write Control Register error %d\n",
	ret);
	goto unlock;
	}

	/* clear the alarm pend flag */
	stat &= ~DS3232_REG_SR_A1F;
	ret = regmap_write(ds3232->regmap, DS3232_REG_SR, stat);
	if (ret) {
	dev_warn(ds3232->dev,
	"Write Status Register error %d\n",
	ret);
	goto unlock;
	}

	rtc_update_irq(ds3232->rtc, 1, RTC_AF \| RTC_IRQF);
	}
	}

	unlock:
	rtc_unlock(ds3232->rtc);

	return IRQ_HANDLED;
	}

	static const struct rtc_class_ops ds3232_rtc_ops = {
	.read_time = ds3232_read_time,
	.set_time = ds3232_set_time,
	.read_alarm = ds3232_read_alarm,
	.set_alarm = ds3232_set_alarm,
	.alarm_irq_enable = ds3232_alarm_irq_enable,
	};

	static int ds3232_nvmem_read(void priv, unsigned int offset, void val,
	size_t bytes)
	{
	struct regmap ds3232_regmap = (struct regmap )priv;

	return regmap_bulk_read(ds3232_regmap, DS3232_REG_SRAM_START + offset,
	val, bytes);
	}

	static int ds3232_nvmem_write(void priv, unsigned int offset, void val,
	size_t bytes)
	{
	struct regmap ds3232_regmap = (struct regmap )priv;

	return regmap_bulk_write(ds3232_regmap, DS3232_REG_SRAM_START + offset,
	val, bytes);
	}

	static int ds3232_probe(struct device dev, struct regmap regmap, int irq,
	const char *name)
	{
	struct ds3232 *ds3232;
	int ret;
	struct nvmem_config nvmem_cfg = {
	.name = "ds3232_sram",
	.stride = 1,
	.size = DS3232_REG_SRAM_SIZE,
	.word_size = 1,
	.reg_read = ds3232_nvmem_read,
	.reg_write = ds3232_nvmem_write,
	.priv = regmap,
	.type = NVMEM_TYPE_BATTERY_BACKED
	};

	ds3232 = devm_kzalloc(dev, sizeof(*ds3232), GFP_KERNEL);
	if (!ds3232)
	return -ENOMEM;

	ds3232->regmap = regmap;
	ds3232->irq = irq;
	ds3232->dev = dev;
	dev_set_drvdata(dev, ds3232);

	ret = ds3232_check_rtc_status(dev);
	if (ret)
	return ret;

	if (ds3232->irq > 0)
	device_init_wakeup(dev, 1);

	ds3232_hwmon_register(dev, name);

	ds3232->rtc = devm_rtc_device_register(dev, name, &ds3232_rtc_ops,
	THIS_MODULE);
	if (IS_ERR(ds3232->rtc))
	return PTR_ERR(ds3232->rtc);

	ret = devm_rtc_nvmem_register(ds3232->rtc, &nvmem_cfg);
	if(ret)
	return ret;

	if (ds3232->irq > 0) {
	ret = devm_request_threaded_irq(dev, ds3232->irq, NULL,
	ds3232_irq,
	IRQF_SHARED \| IRQF_ONESHOT,
	name, dev);
	if (ret) {
	device_set_wakeup_capable(dev, 0);
	ds3232->irq = 0;
	dev_err(dev, "unable to request IRQ\n");
	}
	}

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int ds3232_suspend(struct device *dev)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);

	if (device_may_wakeup(dev)) {
	if (enable_irq_wake(ds3232->irq))
	dev_warn_once(dev, "Cannot set wakeup source\n");
	}

	return 0;
	}

	static int ds3232_resume(struct device *dev)
	{
	struct ds3232 *ds3232 = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
	disable_irq_wake(ds3232->irq);

	return 0;
	}
	#endif

	static const struct dev_pm_ops ds3232_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
	};

	#if IS_ENABLED(CONFIG_I2C)

	static int ds3232_i2c_probe(struct i2c_client *client)
	{
	struct regmap *regmap;
	static const struct regmap_config config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = DS3232_REG_SRAM_END,
	};

	regmap = devm_regmap_init_i2c(client, &config);
	if (IS_ERR(regmap)) {
	dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
	__func__, PTR_ERR(regmap));
	return PTR_ERR(regmap);
	}

	return ds3232_probe(&client->dev, regmap, client->irq, client->name);
	}

	static const struct i2c_device_id ds3232_id[] = {
	{ "ds3232", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ds3232_id);

	static const __maybe_unused struct of_device_id ds3232_of_match[] = {
	{ .compatible = "dallas,ds3232" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, ds3232_of_match);

	static struct i2c_driver ds3232_driver = {
	.driver = {
	.name = "rtc-ds3232",
	.of_match_table = of_match_ptr(ds3232_of_match),
	.pm = &ds3232_pm_ops,
	},
	.probe_new = ds3232_i2c_probe,
	.id_table = ds3232_id,
	};

	static int ds3232_register_driver(void)
	{
	return i2c_add_driver(&ds3232_driver);
	}

	static void ds3232_unregister_driver(void)
	{
	i2c_del_driver(&ds3232_driver);
	}

	#else

	static int ds3232_register_driver(void)
	{
	return 0;
	}

	static void ds3232_unregister_driver(void)
	{
	}

	#endif

	#if IS_ENABLED(CONFIG_SPI_MASTER)

	static int ds3234_probe(struct spi_device *spi)
	{
	int res;
	unsigned int tmp;
	static const struct regmap_config config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = DS3232_REG_SRAM_END,
	.write_flag_mask = 0x80,
	};
	struct regmap *regmap;

	regmap = devm_regmap_init_spi(spi, &config);
	if (IS_ERR(regmap)) {
	dev_err(&spi->dev, "%s: regmap allocation failed: %ld\n",
	__func__, PTR_ERR(regmap));
	return PTR_ERR(regmap);
	}

	spi->mode = SPI_MODE_3;
	spi->bits_per_word = 8;
	spi_setup(spi);

	res = regmap_read(regmap, DS3232_REG_SECONDS, &tmp);
	if (res)
	return res;

	/* Control settings
	*
	* CONTROL_REG
	* BIT 7 6 5 4 3 2 1 0
	* EOSC BBSQW CONV RS2 RS1 INTCN A2IE A1IE
	*
	* 0 0 0 1 1 1 0 0
	*
	* CONTROL_STAT_REG
	* BIT 7 6 5 4 3 2 1 0
	* OSF BB32kHz CRATE1 CRATE0 EN32kHz BSY A2F A1F
	*
	* 1 0 0 0 1 0 0 0
	*/
	res = regmap_read(regmap, DS3232_REG_CR, &tmp);
	if (res)
	return res;
	res = regmap_write(regmap, DS3232_REG_CR, tmp & 0x1c);
	if (res)
	return res;

	res = regmap_read(regmap, DS3232_REG_SR, &tmp);
	if (res)
	return res;
	res = regmap_write(regmap, DS3232_REG_SR, tmp & 0x88);
	if (res)
	return res;

	/* Print our settings */
	res = regmap_read(regmap, DS3232_REG_CR, &tmp);
	if (res)
	return res;
	dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);

	res = regmap_read(regmap, DS3232_REG_SR, &tmp);
	if (res)
	return res;
	dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);

	return ds3232_probe(&spi->dev, regmap, spi->irq, "ds3234");
	}

	static struct spi_driver ds3234_driver = {
	.driver = {
	.name = "ds3234",
	},
	.probe = ds3234_probe,
	};

	static int ds3234_register_driver(void)
	{
	return spi_register_driver(&ds3234_driver);
	}

	static void ds3234_unregister_driver(void)
	{
	spi_unregister_driver(&ds3234_driver);
	}

	#else

	static int ds3234_register_driver(void)
	{
	return 0;
	}

	static void ds3234_unregister_driver(void)
	{
	}

	#endif

	static int __init ds323x_init(void)
	{
	int ret;

	ret = ds3232_register_driver();
	if (ret) {
	pr_err("Failed to register ds3232 driver: %d\n", ret);
	return ret;
	}

	ret = ds3234_register_driver();
	if (ret) {
	pr_err("Failed to register ds3234 driver: %d\n", ret);
	ds3232_unregister_driver();
	}

	return ret;
	}
	module_init(ds323x_init)

	static void __exit ds323x_exit(void)
	{
	ds3234_unregister_driver();
	ds3232_unregister_driver();
	}
	module_exit(ds323x_exit)

	MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
	MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
	MODULE_DESCRIPTION("Maxim/Dallas DS3232/DS3234 RTC Driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("spi:ds3234");