drivers/rtc/rtc-pcf2127.c - third_party/kernel - Git at Google

 /*
  * An I2C and SPI driver for the NXP PCF2127/29 RTC
  * Copyright 2013 Til-Technologies
  *
  * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
  *
  * based on the other drivers in this same directory.
  *
  * Datasheet: http://cache.nxp.com/documents/data_sheet/PCF2127.pdf
  *
  * 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/i2c.h>
 #include <linux/spi/spi.h>
 #include <linux/bcd.h>
 #include <linux/rtc.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/regmap.h>

 #define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
 #define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */

 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
 #define PCF2127_REG_CTRL3_BLF		BIT(2)

 #define PCF2127_REG_SC          (0x03)  /* datetime */
 #define PCF2127_REG_MN          (0x04)
 #define PCF2127_REG_HR          (0x05)
 #define PCF2127_REG_DM          (0x06)
 #define PCF2127_REG_DW          (0x07)
 #define PCF2127_REG_MO          (0x08)
 #define PCF2127_REG_YR          (0x09)

 /* the pcf2127 has 512 bytes nvmem, pcf2129 doesn't */
 #define PCF2127_REG_RAM_addr_MSB       0x1a
 #define PCF2127_REG_RAM_wrt_cmd        0x1c
 #define PCF2127_REG_RAM_rd_cmd         0x1d

 #define PCF2127_OSF             BIT(7)  /* Oscillator Fail flag */

 struct pcf2127 {
 	struct rtc_device *rtc;
 	struct regmap *regmap;
 };

 /*
  * In the routines that deal directly with the pcf2127 hardware, we use
  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  */
 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
 	unsigned char buf[10];
 	int ret;

 	/*
 	 * Avoid reading CTRL2 register as it causes WD_VAL register
 	 * value to reset to 0 which means watchdog is stopped.
 	 */
 	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_CTRL3,
 			       (buf + PCF2127_REG_CTRL3),
 			       ARRAY_SIZE(buf) - PCF2127_REG_CTRL3);
 	if (ret) {
 		dev_err(dev, "%s: read error\n", __func__);
 		return ret;
 	}

 	if (buf[PCF2127_REG_CTRL3] & PCF2127_REG_CTRL3_BLF)
 		dev_info(dev,
 			"low voltage detected, check/replace RTC battery.\n");

 	if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
 		/*
 		 * no need clear the flag here,
 		 * it will be cleared once the new date is saved
 		 */
 		dev_warn(dev,
 			 "oscillator stop detected, date/time is not reliable\n");
 		return -EINVAL;
 	}

 	dev_dbg(dev,
 		"%s: raw data is cr3=%02x, sec=%02x, min=%02x, hr=%02x, "
 		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 		__func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
 		buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
 		buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
 		buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);

 	tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
 	tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
 	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
 	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
 	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
 	tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
 	if (tm->tm_year < 70)
 		tm->tm_year += 100;	/* assume we are in 1970...2069 */

 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 		"mday=%d, mon=%d, year=%d, wday=%d\n",
 		__func__,
 		tm->tm_sec, tm->tm_min, tm->tm_hour,
 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

 	return 0;
 }

 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
 	unsigned char buf[7];
 	int i = 0, err;

 	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 		"mday=%d, mon=%d, year=%d, wday=%d\n",
 		__func__,
 		tm->tm_sec, tm->tm_min, tm->tm_hour,
 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

 	/* hours, minutes and seconds */
 	buf[i++] = bin2bcd(tm->tm_sec);	/* this will also clear OSF flag */
 	buf[i++] = bin2bcd(tm->tm_min);
 	buf[i++] = bin2bcd(tm->tm_hour);
 	buf[i++] = bin2bcd(tm->tm_mday);
 	buf[i++] = tm->tm_wday & 0x07;

 	/* month, 1 - 12 */
 	buf[i++] = bin2bcd(tm->tm_mon + 1);

 	/* year */
 	buf[i++] = bin2bcd(tm->tm_year % 100);

 	/* write register's data */
 	err = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_SC, buf, i);
 	if (err) {
 		dev_err(dev,
 			"%s: err=%d", __func__, err);
 		return err;
 	}

 	return 0;
 }

 #ifdef CONFIG_RTC_INTF_DEV
 static int pcf2127_rtc_ioctl(struct device *dev,
 				unsigned int cmd, unsigned long arg)
 {
 	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
 	int touser;
 	int ret;

 	switch (cmd) {
 	case RTC_VL_READ:
 		ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &touser);
 		if (ret)
 			return ret;

 		touser = touser & PCF2127_REG_CTRL3_BLF ? 1 : 0;

 		if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
 			return -EFAULT;
 		return 0;
 	default:
 		return -ENOIOCTLCMD;
 	}
 }
 #else
 #define pcf2127_rtc_ioctl NULL
 #endif

 static const struct rtc_class_ops pcf2127_rtc_ops = {
 	.ioctl		= pcf2127_rtc_ioctl,
 	.read_time	= pcf2127_rtc_read_time,
 	.set_time	= pcf2127_rtc_set_time,
 };

 static int pcf2127_nvmem_read(void *priv, unsigned int offset,
 			      void *val, size_t bytes)
 {
 	struct pcf2127 *pcf2127 = priv;
 	int ret;
 	unsigned char offsetbuf[] = { offset >> 8, offset };

 	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
 				offsetbuf, 2);
 	if (ret)
 		return ret;

 	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_RAM_rd_cmd,
 			       val, bytes);

 	return ret ?: bytes;
 }

 static int pcf2127_nvmem_write(void *priv, unsigned int offset,
 			       void *val, size_t bytes)
 {
 	struct pcf2127 *pcf2127 = priv;
 	int ret;
 	unsigned char offsetbuf[] = { offset >> 8, offset };

 	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
 				offsetbuf, 2);
 	if (ret)
 		return ret;

 	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_wrt_cmd,
 				val, bytes);

 	return ret ?: bytes;
 }

 static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 			const char *name, bool has_nvmem)
 {
 	struct pcf2127 *pcf2127;
 	int ret = 0;

 	dev_dbg(dev, "%s\n", __func__);

 	pcf2127 = devm_kzalloc(dev, sizeof(*pcf2127), GFP_KERNEL);
 	if (!pcf2127)
 		return -ENOMEM;

 	pcf2127->regmap = regmap;

 	dev_set_drvdata(dev, pcf2127);

 	pcf2127->rtc = devm_rtc_device_register(dev, name, &pcf2127_rtc_ops,
 						THIS_MODULE);
 	if (IS_ERR(pcf2127->rtc))
 		return PTR_ERR(pcf2127->rtc);

 	if (has_nvmem) {
 		struct nvmem_config nvmem_cfg = {
 			.priv = pcf2127,
 			.reg_read = pcf2127_nvmem_read,
 			.reg_write = pcf2127_nvmem_write,
 			.size = 512,
 		};

 		ret = rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
 	}

 	return ret;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id pcf2127_of_match[] = {
 	{ .compatible = "nxp,pcf2127" },
 	{ .compatible = "nxp,pcf2129" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
 #endif

 #if IS_ENABLED(CONFIG_I2C)

 static int pcf2127_i2c_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;

 	ret = i2c_master_send(client, data, count);
 	if (ret != count)
 		return ret < 0 ? ret : -EIO;

 	return 0;
 }

 static int pcf2127_i2c_gather_write(void *context,
 				const void *reg, size_t reg_size,
 				const void *val, size_t val_size)
 {
 	struct device *dev = context;
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;
 	void *buf;

 	if (WARN_ON(reg_size != 1))
 		return -EINVAL;

 	buf = kmalloc(val_size + 1, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	memcpy(buf, reg, 1);
 	memcpy(buf + 1, val, val_size);

 	ret = i2c_master_send(client, buf, val_size + 1);

 	kfree(buf);

 	if (ret != val_size + 1)
 		return ret < 0 ? ret : -EIO;

 	return 0;
 }

 static int pcf2127_i2c_read(void *context, const void *reg, size_t reg_size,
 				void *val, size_t val_size)
 {
 	struct device *dev = context;
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;

 	if (WARN_ON(reg_size != 1))
 		return -EINVAL;

 	ret = i2c_master_send(client, reg, 1);
 	if (ret != 1)
 		return ret < 0 ? ret : -EIO;

 	ret = i2c_master_recv(client, val, val_size);
 	if (ret != val_size)
 		return ret < 0 ? ret : -EIO;

 	return 0;
 }

 /*
  * The reason we need this custom regmap_bus instead of using regmap_init_i2c()
  * is that the STOP condition is required between set register address and
  * read register data when reading from registers.
  */
 static const struct regmap_bus pcf2127_i2c_regmap = {
 	.write = pcf2127_i2c_write,
 	.gather_write = pcf2127_i2c_gather_write,
 	.read = pcf2127_i2c_read,
 };

 static struct i2c_driver pcf2127_i2c_driver;

 static int pcf2127_i2c_probe(struct i2c_client *client,
 				const struct i2c_device_id *id)
 {
 	struct regmap *regmap;
 	static const struct regmap_config config = {
 		.reg_bits = 8,
 		.val_bits = 8,
 	};

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

 	regmap = devm_regmap_init(&client->dev, &pcf2127_i2c_regmap,
 					&client->dev, &config);
 	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
 			__func__, PTR_ERR(regmap));
 		return PTR_ERR(regmap);
 	}

 	return pcf2127_probe(&client->dev, regmap,
 			     pcf2127_i2c_driver.driver.name, id->driver_data);
 }

 static const struct i2c_device_id pcf2127_i2c_id[] = {
 	{ "pcf2127", 1 },
 	{ "pcf2129", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, pcf2127_i2c_id);

 static struct i2c_driver pcf2127_i2c_driver = {
 	.driver		= {
 		.name	= "rtc-pcf2127-i2c",
 		.of_match_table = of_match_ptr(pcf2127_of_match),
 	},
 	.probe		= pcf2127_i2c_probe,
 	.id_table	= pcf2127_i2c_id,
 };

 static int pcf2127_i2c_register_driver(void)
 {
 	return i2c_add_driver(&pcf2127_i2c_driver);
 }

 static void pcf2127_i2c_unregister_driver(void)
 {
 	i2c_del_driver(&pcf2127_i2c_driver);
 }

 #else

 static int pcf2127_i2c_register_driver(void)
 {
 	return 0;
 }

 static void pcf2127_i2c_unregister_driver(void)
 {
 }

 #endif

 #if IS_ENABLED(CONFIG_SPI_MASTER)

 static struct spi_driver pcf2127_spi_driver;

 static int pcf2127_spi_probe(struct spi_device *spi)
 {
 	static const struct regmap_config config = {
 		.reg_bits = 8,
 		.val_bits = 8,
 		.read_flag_mask = 0xa0,
 		.write_flag_mask = 0x20,
 	};
 	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);
 	}

 	return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name,
 			     spi_get_device_id(spi)->driver_data);
 }

 static const struct spi_device_id pcf2127_spi_id[] = {
 	{ "pcf2127", 1 },
 	{ "pcf2129", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, pcf2127_spi_id);

 static struct spi_driver pcf2127_spi_driver = {
 	.driver		= {
 		.name	= "rtc-pcf2127-spi",
 		.of_match_table = of_match_ptr(pcf2127_of_match),
 	},
 	.probe		= pcf2127_spi_probe,
 	.id_table	= pcf2127_spi_id,
 };

 static int pcf2127_spi_register_driver(void)
 {
 	return spi_register_driver(&pcf2127_spi_driver);
 }

 static void pcf2127_spi_unregister_driver(void)
 {
 	spi_unregister_driver(&pcf2127_spi_driver);
 }

 #else

 static int pcf2127_spi_register_driver(void)
 {
 	return 0;
 }

 static void pcf2127_spi_unregister_driver(void)
 {
 }

 #endif

 static int __init pcf2127_init(void)
 {
 	int ret;

 	ret = pcf2127_i2c_register_driver();
 	if (ret) {
 		pr_err("Failed to register pcf2127 i2c driver: %d\n", ret);
 		return ret;
 	}

 	ret = pcf2127_spi_register_driver();
 	if (ret) {
 		pr_err("Failed to register pcf2127 spi driver: %d\n", ret);
 		pcf2127_i2c_unregister_driver();
 	}

 	return ret;
 }
 module_init(pcf2127_init)

 static void __exit pcf2127_exit(void)
 {
 	pcf2127_spi_unregister_driver();
 	pcf2127_i2c_unregister_driver();
 }
 module_exit(pcf2127_exit)

 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
 MODULE_DESCRIPTION("NXP PCF2127/29 RTC driver");
 MODULE_LICENSE("GPL v2");
	/*
	* An I2C and SPI driver for the NXP PCF2127/29 RTC
	* Copyright 2013 Til-Technologies
	*
	* Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
	*
	* based on the other drivers in this same directory.
	*
	* Datasheet: http://cache.nxp.com/documents/data_sheet/PCF2127.pdf
	*
	* 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/i2c.h>
	#include <linux/spi/spi.h>
	#include <linux/bcd.h>
	#include <linux/rtc.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/regmap.h>

	#define PCF2127_REG_CTRL1 (0x00) /* Control Register 1 */
	#define PCF2127_REG_CTRL2 (0x01) /* Control Register 2 */

	#define PCF2127_REG_CTRL3 (0x02) /* Control Register 3 */
	#define PCF2127_REG_CTRL3_BLF BIT(2)

	#define PCF2127_REG_SC (0x03) /* datetime */
	#define PCF2127_REG_MN (0x04)
	#define PCF2127_REG_HR (0x05)
	#define PCF2127_REG_DM (0x06)
	#define PCF2127_REG_DW (0x07)
	#define PCF2127_REG_MO (0x08)
	#define PCF2127_REG_YR (0x09)

	/* the pcf2127 has 512 bytes nvmem, pcf2129 doesn't */
	#define PCF2127_REG_RAM_addr_MSB 0x1a
	#define PCF2127_REG_RAM_wrt_cmd 0x1c
	#define PCF2127_REG_RAM_rd_cmd 0x1d

	#define PCF2127_OSF BIT(7) /* Oscillator Fail flag */

	struct pcf2127 {
	struct rtc_device *rtc;
	struct regmap *regmap;
	};

	/*
	* In the routines that deal directly with the pcf2127 hardware, we use
	* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
	*/
	static int pcf2127_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
	unsigned char buf[10];
	int ret;

	/*
	* Avoid reading CTRL2 register as it causes WD_VAL register
	* value to reset to 0 which means watchdog is stopped.
	*/
	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_CTRL3,
	(buf + PCF2127_REG_CTRL3),
	ARRAY_SIZE(buf) - PCF2127_REG_CTRL3);
	if (ret) {
	dev_err(dev, "%s: read error\n", __func__);
	return ret;
	}

	if (buf[PCF2127_REG_CTRL3] & PCF2127_REG_CTRL3_BLF)
	dev_info(dev,
	"low voltage detected, check/replace RTC battery.\n");

	if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
	/*
	* no need clear the flag here,
	* it will be cleared once the new date is saved
	*/
	dev_warn(dev,
	"oscillator stop detected, date/time is not reliable\n");
	return -EINVAL;
	}

	dev_dbg(dev,
	"%s: raw data is cr3=%02x, sec=%02x, min=%02x, hr=%02x, "
	"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
	__func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
	buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
	buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
	buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);

	tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
	tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
	tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
	if (tm->tm_year < 70)
	tm->tm_year += 100; /* assume we are in 1970...2069 */

	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
	"mday=%d, mon=%d, year=%d, wday=%d\n",
	__func__,
	tm->tm_sec, tm->tm_min, tm->tm_hour,
	tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	return 0;
	}

	static int pcf2127_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
	unsigned char buf[7];
	int i = 0, err;

	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
	"mday=%d, mon=%d, year=%d, wday=%d\n",
	__func__,
	tm->tm_sec, tm->tm_min, tm->tm_hour,
	tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	/* hours, minutes and seconds */
	buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
	buf[i++] = bin2bcd(tm->tm_min);
	buf[i++] = bin2bcd(tm->tm_hour);
	buf[i++] = bin2bcd(tm->tm_mday);
	buf[i++] = tm->tm_wday & 0x07;

	/* month, 1 - 12 */
	buf[i++] = bin2bcd(tm->tm_mon + 1);

	/* year */
	buf[i++] = bin2bcd(tm->tm_year % 100);

	/* write register's data */
	err = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_SC, buf, i);
	if (err) {
	dev_err(dev,
	"%s: err=%d", __func__, err);
	return err;
	}

	return 0;
	}

	#ifdef CONFIG_RTC_INTF_DEV
	static int pcf2127_rtc_ioctl(struct device *dev,
	unsigned int cmd, unsigned long arg)
	{
	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
	int touser;
	int ret;

	switch (cmd) {
	case RTC_VL_READ:
	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &touser);
	if (ret)
	return ret;

	touser = touser & PCF2127_REG_CTRL3_BLF ? 1 : 0;

	if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
	return -EFAULT;
	return 0;
	default:
	return -ENOIOCTLCMD;
	}
	}
	#else
	#define pcf2127_rtc_ioctl NULL
	#endif

	static const struct rtc_class_ops pcf2127_rtc_ops = {
	.ioctl = pcf2127_rtc_ioctl,
	.read_time = pcf2127_rtc_read_time,
	.set_time = pcf2127_rtc_set_time,
	};

	static int pcf2127_nvmem_read(void *priv, unsigned int offset,
	void *val, size_t bytes)
	{
	struct pcf2127 *pcf2127 = priv;
	int ret;
	unsigned char offsetbuf[] = { offset >> 8, offset };

	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
	offsetbuf, 2);
	if (ret)
	return ret;

	ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_RAM_rd_cmd,
	val, bytes);

	return ret ?: bytes;
	}

	static int pcf2127_nvmem_write(void *priv, unsigned int offset,
	void *val, size_t bytes)
	{
	struct pcf2127 *pcf2127 = priv;
	int ret;
	unsigned char offsetbuf[] = { offset >> 8, offset };

	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
	offsetbuf, 2);
	if (ret)
	return ret;

	ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_wrt_cmd,
	val, bytes);

	return ret ?: bytes;
	}

	static int pcf2127_probe(struct device dev, struct regmap regmap,
	const char *name, bool has_nvmem)
	{
	struct pcf2127 *pcf2127;
	int ret = 0;

	dev_dbg(dev, "%s\n", __func__);

	pcf2127 = devm_kzalloc(dev, sizeof(*pcf2127), GFP_KERNEL);
	if (!pcf2127)
	return -ENOMEM;

	pcf2127->regmap = regmap;

	dev_set_drvdata(dev, pcf2127);

	pcf2127->rtc = devm_rtc_device_register(dev, name, &pcf2127_rtc_ops,
	THIS_MODULE);
	if (IS_ERR(pcf2127->rtc))
	return PTR_ERR(pcf2127->rtc);

	if (has_nvmem) {
	struct nvmem_config nvmem_cfg = {
	.priv = pcf2127,
	.reg_read = pcf2127_nvmem_read,
	.reg_write = pcf2127_nvmem_write,
	.size = 512,
	};

	ret = rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
	}

	return ret;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id pcf2127_of_match[] = {
	{ .compatible = "nxp,pcf2127" },
	{ .compatible = "nxp,pcf2129" },
	{}
	};
	MODULE_DEVICE_TABLE(of, pcf2127_of_match);
	#endif

	#if IS_ENABLED(CONFIG_I2C)

	static int pcf2127_i2c_write(void context, const void data, size_t count)
	{
	struct device *dev = context;
	struct i2c_client *client = to_i2c_client(dev);
	int ret;

	ret = i2c_master_send(client, data, count);
	if (ret != count)
	return ret < 0 ? ret : -EIO;

	return 0;
	}

	static int pcf2127_i2c_gather_write(void *context,
	const void *reg, size_t reg_size,
	const void *val, size_t val_size)
	{
	struct device *dev = context;
	struct i2c_client *client = to_i2c_client(dev);
	int ret;
	void *buf;

	if (WARN_ON(reg_size != 1))
	return -EINVAL;

	buf = kmalloc(val_size + 1, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	memcpy(buf, reg, 1);
	memcpy(buf + 1, val, val_size);

	ret = i2c_master_send(client, buf, val_size + 1);

	kfree(buf);

	if (ret != val_size + 1)
	return ret < 0 ? ret : -EIO;

	return 0;
	}

	static int pcf2127_i2c_read(void context, const void reg, size_t reg_size,
	void *val, size_t val_size)
	{
	struct device *dev = context;
	struct i2c_client *client = to_i2c_client(dev);
	int ret;

	if (WARN_ON(reg_size != 1))
	return -EINVAL;

	ret = i2c_master_send(client, reg, 1);
	if (ret != 1)
	return ret < 0 ? ret : -EIO;

	ret = i2c_master_recv(client, val, val_size);
	if (ret != val_size)
	return ret < 0 ? ret : -EIO;

	return 0;
	}

	/*
	* The reason we need this custom regmap_bus instead of using regmap_init_i2c()
	* is that the STOP condition is required between set register address and
	* read register data when reading from registers.
	*/
	static const struct regmap_bus pcf2127_i2c_regmap = {
	.write = pcf2127_i2c_write,
	.gather_write = pcf2127_i2c_gather_write,
	.read = pcf2127_i2c_read,
	};

	static struct i2c_driver pcf2127_i2c_driver;

	static int pcf2127_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct regmap *regmap;
	static const struct regmap_config config = {
	.reg_bits = 8,
	.val_bits = 8,
	};

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

	regmap = devm_regmap_init(&client->dev, &pcf2127_i2c_regmap,
	&client->dev, &config);
	if (IS_ERR(regmap)) {
	dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
	__func__, PTR_ERR(regmap));
	return PTR_ERR(regmap);
	}

	return pcf2127_probe(&client->dev, regmap,
	pcf2127_i2c_driver.driver.name, id->driver_data);
	}

	static const struct i2c_device_id pcf2127_i2c_id[] = {
	{ "pcf2127", 1 },
	{ "pcf2129", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, pcf2127_i2c_id);

	static struct i2c_driver pcf2127_i2c_driver = {
	.driver = {
	.name = "rtc-pcf2127-i2c",
	.of_match_table = of_match_ptr(pcf2127_of_match),
	},
	.probe = pcf2127_i2c_probe,
	.id_table = pcf2127_i2c_id,
	};

	static int pcf2127_i2c_register_driver(void)
	{
	return i2c_add_driver(&pcf2127_i2c_driver);
	}

	static void pcf2127_i2c_unregister_driver(void)
	{
	i2c_del_driver(&pcf2127_i2c_driver);
	}

	#else

	static int pcf2127_i2c_register_driver(void)
	{
	return 0;
	}

	static void pcf2127_i2c_unregister_driver(void)
	{
	}

	#endif

	#if IS_ENABLED(CONFIG_SPI_MASTER)

	static struct spi_driver pcf2127_spi_driver;

	static int pcf2127_spi_probe(struct spi_device *spi)
	{
	static const struct regmap_config config = {
	.reg_bits = 8,
	.val_bits = 8,
	.read_flag_mask = 0xa0,
	.write_flag_mask = 0x20,
	};
	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);
	}

	return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name,
	spi_get_device_id(spi)->driver_data);
	}

	static const struct spi_device_id pcf2127_spi_id[] = {
	{ "pcf2127", 1 },
	{ "pcf2129", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(spi, pcf2127_spi_id);

	static struct spi_driver pcf2127_spi_driver = {
	.driver = {
	.name = "rtc-pcf2127-spi",
	.of_match_table = of_match_ptr(pcf2127_of_match),
	},
	.probe = pcf2127_spi_probe,
	.id_table = pcf2127_spi_id,
	};

	static int pcf2127_spi_register_driver(void)
	{
	return spi_register_driver(&pcf2127_spi_driver);
	}

	static void pcf2127_spi_unregister_driver(void)
	{
	spi_unregister_driver(&pcf2127_spi_driver);
	}

	#else

	static int pcf2127_spi_register_driver(void)
	{
	return 0;
	}

	static void pcf2127_spi_unregister_driver(void)
	{
	}

	#endif

	static int __init pcf2127_init(void)
	{
	int ret;

	ret = pcf2127_i2c_register_driver();
	if (ret) {
	pr_err("Failed to register pcf2127 i2c driver: %d\n", ret);
	return ret;
	}

	ret = pcf2127_spi_register_driver();
	if (ret) {
	pr_err("Failed to register pcf2127 spi driver: %d\n", ret);
	pcf2127_i2c_unregister_driver();
	}

	return ret;
	}
	module_init(pcf2127_init)

	static void __exit pcf2127_exit(void)
	{
	pcf2127_spi_unregister_driver();
	pcf2127_i2c_unregister_driver();
	}
	module_exit(pcf2127_exit)

	MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
	MODULE_DESCRIPTION("NXP PCF2127/29 RTC driver");
	MODULE_LICENSE("GPL v2");