/*
   * An I2C driver for the NXP PCF2127 RTC
   * Copyright 2013 Til-Technologies
   *
   * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
   *
   * based on the other drivers in this same directory.
   *
   * http://www.nxp.com/documents/data_sheet/PCF2127AT.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/bcd.h>
  #include <linux/rtc.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/of.h>
  
  #define DRV_VERSION "0.0.1"
  
  #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_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)
  
  static struct i2c_driver pcf2127_driver;
  
  struct pcf2127 {
  	struct rtc_device *rtc;
  	int voltage_low; /* indicates if a low_voltage was detected */
  };
  
  /*
   * 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_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  {
  	struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
  	unsigned char buf[10] = { PCF2127_REG_CTRL1 };
  
  	/* read registers */
  	if (i2c_master_send(client, buf, 1) != 1 ||
  		i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  
  	if (buf[PCF2127_REG_CTRL3] & 0x04) {
  		pcf2127->voltage_low = 1;
  		dev_info(&client->dev,
  			"low voltage detected, date/time is not reliable.
  ");
  	}
  
  	dev_dbg(&client->dev,
  		"%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
  		"sec=%02x, min=%02x, hr=%02x, "
  		"mday=%02x, wday=%02x, mon=%02x, year=%02x
  ",
  		__func__,
  		buf[0], buf[1], buf[2],
  		buf[3], buf[4], buf[5],
  		buf[6], buf[7], buf[8], buf[9]);
  
  
  	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(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  		"mday=%d, mon=%d, year=%d, wday=%d
  ",
  		__func__,
  		tm->tm_sec, tm->tm_min, tm->tm_hour,
  		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  
  	/* the clock can give out invalid datetime, but we cannot return
  	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
  	 */
  	if (rtc_valid_tm(tm) < 0)
  		dev_err(&client->dev, "retrieved date/time is not valid.
  ");
  
  	return 0;
  }
  
  static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  {
  	unsigned char buf[8];
  	int i = 0, err;
  
  	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
  		"mday=%d, mon=%d, year=%d, wday=%d
  ",
  		__func__,
  		tm->tm_sec, tm->tm_min, tm->tm_hour,
  		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  
  	/* start register address */
  	buf[i++] = PCF2127_REG_SC;
  
  	/* hours, minutes and seconds */
  	buf[i++] = bin2bcd(tm->tm_sec);
  	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 = i2c_master_send(client, buf, i);
  	if (err != i) {
  		dev_err(&client->dev,
  			"%s: err=%d", __func__, err);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  #ifdef CONFIG_RTC_INTF_DEV
  static int pcf2127_rtc_ioctl(struct device *dev,
  				unsigned int cmd, unsigned long arg)
  {
  	struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
  
  	switch (cmd) {
  	case RTC_VL_READ:
  		if (pcf2127->voltage_low)
  			dev_info(dev, "low voltage detected, date/time is not reliable.
  ");
  
  		if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
  					sizeof(int)))
  			return -EFAULT;
  		return 0;
  	default:
  		return -ENOIOCTLCMD;
  	}
  }
  #else
  #define pcf2127_rtc_ioctl NULL
  #endif
  
  static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf2127_get_datetime(to_i2c_client(dev), tm);
  }
  
  static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf2127_set_datetime(to_i2c_client(dev), tm);
  }
  
  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_probe(struct i2c_client *client,
  				const struct i2c_device_id *id)
  {
  	struct pcf2127 *pcf2127;
  
  	dev_dbg(&client->dev, "%s
  ", __func__);
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  		return -ENODEV;
  
  	pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
  				GFP_KERNEL);
  	if (!pcf2127)
  		return -ENOMEM;
  
  	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "
  ");
  
  	i2c_set_clientdata(client, pcf2127);
  
  	pcf2127->rtc = devm_rtc_device_register(&client->dev,
  				pcf2127_driver.driver.name,
  				&pcf2127_rtc_ops, THIS_MODULE);
  
  	return PTR_ERR_OR_ZERO(pcf2127->rtc);
  }
  
  static const struct i2c_device_id pcf2127_id[] = {
  	{ "pcf2127", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, pcf2127_id);
  
  #ifdef CONFIG_OF
  static const struct of_device_id pcf2127_of_match[] = {
  	{ .compatible = "nxp,pcf2127" },
  	{}
  };
  MODULE_DEVICE_TABLE(of, pcf2127_of_match);
  #endif
  
  static struct i2c_driver pcf2127_driver = {
  	.driver		= {
  		.name	= "rtc-pcf2127",
  		.owner	= THIS_MODULE,
  		.of_match_table = of_match_ptr(pcf2127_of_match),
  	},
  	.probe		= pcf2127_probe,
  	.id_table	= pcf2127_id,
  };
  
  module_i2c_driver(pcf2127_driver);
  
  MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
  MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);