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

 #define DRIVER_NAME "rtc-pcf8523"

 #define REG_CONTROL1 0x00
 #define REG_CONTROL1_CAP_SEL (1 << 7)
 #define REG_CONTROL1_STOP    (1 << 5)

 #define REG_CONTROL3 0x02
 #define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
 #define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
 #define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
 #define REG_CONTROL3_PM_MASK 0xe0
 #define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */

 #define REG_SECONDS  0x03
 #define REG_SECONDS_OS (1 << 7)

 #define REG_MINUTES  0x04
 #define REG_HOURS    0x05
 #define REG_DAYS     0x06
 #define REG_WEEKDAYS 0x07
 #define REG_MONTHS   0x08
 #define REG_YEARS    0x09

 #define REG_OFFSET   0x0e
 #define REG_OFFSET_MODE BIT(7)

 static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
 {
 	struct i2c_msg msgs[2];
 	u8 value = 0;
 	int err;

 	msgs[0].addr = client->addr;
 	msgs[0].flags = 0;
 	msgs[0].len = sizeof(reg);
 	msgs[0].buf = &reg;

 	msgs[1].addr = client->addr;
 	msgs[1].flags = I2C_M_RD;
 	msgs[1].len = sizeof(value);
 	msgs[1].buf = &value;

 	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (err < 0)
 		return err;

 	*valuep = value;

 	return 0;
 }

 static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
 {
 	u8 buffer[2] = { reg, value };
 	struct i2c_msg msg;
 	int err;

 	msg.addr = client->addr;
 	msg.flags = 0;
 	msg.len = sizeof(buffer);
 	msg.buf = buffer;

 	err = i2c_transfer(client->adapter, &msg, 1);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static int pcf8523_voltage_low(struct i2c_client *client)
 {
 	u8 value;
 	int err;

 	err = pcf8523_read(client, REG_CONTROL3, &value);
 	if (err < 0)
 		return err;

 	return !!(value & REG_CONTROL3_BLF);
 }

 static int pcf8523_load_capacitance(struct i2c_client *client)
 {
 	u32 load;
 	u8 value;
 	int err;

 	err = pcf8523_read(client, REG_CONTROL1, &value);
 	if (err < 0)
 		return err;

 	load = 12500;
 	of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
 			     &load);

 	switch (load) {
 	default:
 		dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
 			 load);
 		fallthrough;
 	case 12500:
 		value |= REG_CONTROL1_CAP_SEL;
 		break;
 	case 7000:
 		value &= ~REG_CONTROL1_CAP_SEL;
 		break;
 	}

 	err = pcf8523_write(client, REG_CONTROL1, value);

 	return err;
 }

 static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
 {
 	u8 value;
 	int err;

 	err = pcf8523_read(client, REG_CONTROL3, &value);
 	if (err < 0)
 		return err;

 	value = (value & ~REG_CONTROL3_PM_MASK) | pm;

 	err = pcf8523_write(client, REG_CONTROL3, value);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static int pcf8523_stop_rtc(struct i2c_client *client)
 {
 	u8 value;
 	int err;

 	err = pcf8523_read(client, REG_CONTROL1, &value);
 	if (err < 0)
 		return err;

 	value |= REG_CONTROL1_STOP;

 	err = pcf8523_write(client, REG_CONTROL1, value);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static int pcf8523_start_rtc(struct i2c_client *client)
 {
 	u8 value;
 	int err;

 	err = pcf8523_read(client, REG_CONTROL1, &value);
 	if (err < 0)
 		return err;

 	value &= ~REG_CONTROL1_STOP;

 	err = pcf8523_write(client, REG_CONTROL1, value);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	u8 start = REG_SECONDS, regs[7];
 	struct i2c_msg msgs[2];
 	int err;

 	err = pcf8523_voltage_low(client);
 	if (err < 0) {
 		return err;
 	} else if (err > 0) {
 		dev_err(dev, "low voltage detected, time is unreliable\n");
 		return -EINVAL;
 	}

 	msgs[0].addr = client->addr;
 	msgs[0].flags = 0;
 	msgs[0].len = 1;
 	msgs[0].buf = &start;

 	msgs[1].addr = client->addr;
 	msgs[1].flags = I2C_M_RD;
 	msgs[1].len = sizeof(regs);
 	msgs[1].buf = regs;

 	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (err < 0)
 		return err;

 	if (regs[0] & REG_SECONDS_OS)
 		return -EINVAL;

 	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
 	tm->tm_min = bcd2bin(regs[1] & 0x7f);
 	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
 	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
 	tm->tm_wday = regs[4] & 0x7;
 	tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
 	tm->tm_year = bcd2bin(regs[6]) + 100;

 	return 0;
 }

 static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct i2c_msg msg;
 	u8 regs[8];
 	int err;

 	/*
 	 * The hardware can only store values between 0 and 99 in it's YEAR
 	 * register (with 99 overflowing to 0 on increment).
 	 * After 2100-02-28 we could start interpreting the year to be in the
 	 * interval [2100, 2199], but there is no path to switch in a smooth way
 	 * because the chip handles YEAR=0x00 (and the out-of-spec
 	 * YEAR=0xa0) as a leap year, but 2100 isn't.
 	 */
 	if (tm->tm_year < 100 || tm->tm_year >= 200)
 		return -EINVAL;

 	err = pcf8523_stop_rtc(client);
 	if (err < 0)
 		return err;

 	regs[0] = REG_SECONDS;
 	/* This will purposely overwrite REG_SECONDS_OS */
 	regs[1] = bin2bcd(tm->tm_sec);
 	regs[2] = bin2bcd(tm->tm_min);
 	regs[3] = bin2bcd(tm->tm_hour);
 	regs[4] = bin2bcd(tm->tm_mday);
 	regs[5] = tm->tm_wday;
 	regs[6] = bin2bcd(tm->tm_mon + 1);
 	regs[7] = bin2bcd(tm->tm_year - 100);

 	msg.addr = client->addr;
 	msg.flags = 0;
 	msg.len = sizeof(regs);
 	msg.buf = regs;

 	err = i2c_transfer(client->adapter, &msg, 1);
 	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.
 		 */
 		pcf8523_start_rtc(client);
 		return err;
 	}

 	return pcf8523_start_rtc(client);
 }

 #ifdef CONFIG_RTC_INTF_DEV
 static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
 			     unsigned long arg)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;

 	switch (cmd) {
 	case RTC_VL_READ:
 		ret = pcf8523_voltage_low(client);
 		if (ret < 0)
 			return ret;
 		if (ret)
 			ret = RTC_VL_BACKUP_LOW;

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

 	default:
 		return -ENOIOCTLCMD;
 	}
 }
 #else
 #define pcf8523_rtc_ioctl NULL
 #endif

 static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int err;
 	u8 value;
 	s8 val;

 	err = pcf8523_read(client, REG_OFFSET, &value);
 	if (err < 0)
 		return err;

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

 	return 0;
 }

 static int pcf8523_rtc_set_offset(struct device *dev, long offset)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	long reg_m0, reg_m1;
 	u8 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) | REG_OFFSET_MODE;

 	return pcf8523_write(client, REG_OFFSET, value);
 }

 static const struct rtc_class_ops pcf8523_rtc_ops = {
 	.read_time = pcf8523_rtc_read_time,
 	.set_time = pcf8523_rtc_set_time,
 	.ioctl = pcf8523_rtc_ioctl,
 	.read_offset = pcf8523_rtc_read_offset,
 	.set_offset = pcf8523_rtc_set_offset,
 };

 static int pcf8523_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct rtc_device *rtc;
 	int err;

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

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

 	err = pcf8523_set_pm(client, 0);
 	if (err < 0)
 		return err;

 	rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
 				       &pcf8523_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);

 	return 0;
 }

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

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

 static struct i2c_driver pcf8523_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table = of_match_ptr(pcf8523_of_match),
 	},
 	.probe = 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/i2c.h>
	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/of.h>

	#define DRIVER_NAME "rtc-pcf8523"

	#define REG_CONTROL1 0x00
	#define REG_CONTROL1_CAP_SEL (1 << 7)
	#define REG_CONTROL1_STOP (1 << 5)

	#define REG_CONTROL3 0x02
	#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
	#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
	#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
	#define REG_CONTROL3_PM_MASK 0xe0
	#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */

	#define REG_SECONDS 0x03
	#define REG_SECONDS_OS (1 << 7)

	#define REG_MINUTES 0x04
	#define REG_HOURS 0x05
	#define REG_DAYS 0x06
	#define REG_WEEKDAYS 0x07
	#define REG_MONTHS 0x08
	#define REG_YEARS 0x09

	#define REG_OFFSET 0x0e
	#define REG_OFFSET_MODE BIT(7)

	static int pcf8523_read(struct i2c_client client, u8 reg, u8 valuep)
	{
	struct i2c_msg msgs[2];
	u8 value = 0;
	int err;

	msgs[0].addr = client->addr;
	msgs[0].flags = 0;
	msgs[0].len = sizeof(reg);
	msgs[0].buf = ®

	msgs[1].addr = client->addr;
	msgs[1].flags = I2C_M_RD;
	msgs[1].len = sizeof(value);
	msgs[1].buf = &value;

	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	if (err < 0)
	return err;

	*valuep = value;

	return 0;
	}

	static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
	{
	u8 buffer[2] = { reg, value };
	struct i2c_msg msg;
	int err;

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = sizeof(buffer);
	msg.buf = buffer;

	err = i2c_transfer(client->adapter, &msg, 1);
	if (err < 0)
	return err;

	return 0;
	}

	static int pcf8523_voltage_low(struct i2c_client *client)
	{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL3, &value);
	if (err < 0)
	return err;

	return !!(value & REG_CONTROL3_BLF);
	}

	static int pcf8523_load_capacitance(struct i2c_client *client)
	{
	u32 load;
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
	return err;

	load = 12500;
	of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
	&load);

	switch (load) {
	default:
	dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
	load);
	fallthrough;
	case 12500:
	value \|= REG_CONTROL1_CAP_SEL;
	break;
	case 7000:
	value &= ~REG_CONTROL1_CAP_SEL;
	break;
	}

	err = pcf8523_write(client, REG_CONTROL1, value);

	return err;
	}

	static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
	{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL3, &value);
	if (err < 0)
	return err;

	value = (value & ~REG_CONTROL3_PM_MASK) \| pm;

	err = pcf8523_write(client, REG_CONTROL3, value);
	if (err < 0)
	return err;

	return 0;
	}

	static int pcf8523_stop_rtc(struct i2c_client *client)
	{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
	return err;

	value \|= REG_CONTROL1_STOP;

	err = pcf8523_write(client, REG_CONTROL1, value);
	if (err < 0)
	return err;

	return 0;
	}

	static int pcf8523_start_rtc(struct i2c_client *client)
	{
	u8 value;
	int err;

	err = pcf8523_read(client, REG_CONTROL1, &value);
	if (err < 0)
	return err;

	value &= ~REG_CONTROL1_STOP;

	err = pcf8523_write(client, REG_CONTROL1, value);
	if (err < 0)
	return err;

	return 0;
	}

	static int pcf8523_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	u8 start = REG_SECONDS, regs[7];
	struct i2c_msg msgs[2];
	int err;

	err = pcf8523_voltage_low(client);
	if (err < 0) {
	return err;
	} else if (err > 0) {
	dev_err(dev, "low voltage detected, time is unreliable\n");
	return -EINVAL;
	}

	msgs[0].addr = client->addr;
	msgs[0].flags = 0;
	msgs[0].len = 1;
	msgs[0].buf = &start;

	msgs[1].addr = client->addr;
	msgs[1].flags = I2C_M_RD;
	msgs[1].len = sizeof(regs);
	msgs[1].buf = regs;

	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
	if (err < 0)
	return err;

	if (regs[0] & REG_SECONDS_OS)
	return -EINVAL;

	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
	tm->tm_min = bcd2bin(regs[1] & 0x7f);
	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
	tm->tm_wday = regs[4] & 0x7;
	tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
	tm->tm_year = bcd2bin(regs[6]) + 100;

	return 0;
	}

	static int pcf8523_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct i2c_msg msg;
	u8 regs[8];
	int err;

	/*
	* The hardware can only store values between 0 and 99 in it's YEAR
	* register (with 99 overflowing to 0 on increment).
	* After 2100-02-28 we could start interpreting the year to be in the
	* interval [2100, 2199], but there is no path to switch in a smooth way
	* because the chip handles YEAR=0x00 (and the out-of-spec
	* YEAR=0xa0) as a leap year, but 2100 isn't.
	*/
	if (tm->tm_year < 100 \|\| tm->tm_year >= 200)
	return -EINVAL;

	err = pcf8523_stop_rtc(client);
	if (err < 0)
	return err;

	regs[0] = REG_SECONDS;
	/* This will purposely overwrite REG_SECONDS_OS */
	regs[1] = bin2bcd(tm->tm_sec);
	regs[2] = bin2bcd(tm->tm_min);
	regs[3] = bin2bcd(tm->tm_hour);
	regs[4] = bin2bcd(tm->tm_mday);
	regs[5] = tm->tm_wday;
	regs[6] = bin2bcd(tm->tm_mon + 1);
	regs[7] = bin2bcd(tm->tm_year - 100);

	msg.addr = client->addr;
	msg.flags = 0;
	msg.len = sizeof(regs);
	msg.buf = regs;

	err = i2c_transfer(client->adapter, &msg, 1);
	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.
	*/
	pcf8523_start_rtc(client);
	return err;
	}

	return pcf8523_start_rtc(client);
	}

	#ifdef CONFIG_RTC_INTF_DEV
	static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
	unsigned long arg)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int ret;

	switch (cmd) {
	case RTC_VL_READ:
	ret = pcf8523_voltage_low(client);
	if (ret < 0)
	return ret;
	if (ret)
	ret = RTC_VL_BACKUP_LOW;

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

	default:
	return -ENOIOCTLCMD;
	}
	}
	#else
	#define pcf8523_rtc_ioctl NULL
	#endif

	static int pcf8523_rtc_read_offset(struct device dev, long offset)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int err;
	u8 value;
	s8 val;

	err = pcf8523_read(client, REG_OFFSET, &value);
	if (err < 0)
	return err;

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

	return 0;
	}

	static int pcf8523_rtc_set_offset(struct device *dev, long offset)
	{
	struct i2c_client *client = to_i2c_client(dev);
	long reg_m0, reg_m1;
	u8 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) \| REG_OFFSET_MODE;

	return pcf8523_write(client, REG_OFFSET, value);
	}

	static const struct rtc_class_ops pcf8523_rtc_ops = {
	.read_time = pcf8523_rtc_read_time,
	.set_time = pcf8523_rtc_set_time,
	.ioctl = pcf8523_rtc_ioctl,
	.read_offset = pcf8523_rtc_read_offset,
	.set_offset = pcf8523_rtc_set_offset,
	};

	static int pcf8523_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct rtc_device *rtc;
	int err;

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

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

	err = pcf8523_set_pm(client, 0);
	if (err < 0)
	return err;

	rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
	&pcf8523_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
	return PTR_ERR(rtc);

	return 0;
	}

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

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

	static struct i2c_driver pcf8523_driver = {
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = of_match_ptr(pcf8523_of_match),
	},
	.probe = 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");