/*
   * An SPI driver for the Philips PCF2123 RTC
   * Copyright 2009 Cyber Switching, Inc.
   *
   * Author: Chris Verges <chrisv@cyberswitching.com>
   * Maintainers: http://www.cyberswitching.com
   *
   * based on the RS5C348 driver in this same directory.
   *
   * Thanks to Christian Pellegrin <chripell@fsfe.org> for
   * the sysfs contributions to this driver.
   *
   * 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.
   *
   * Please note that the CS is active high, so platform data
   * should look something like:
   *
   * static struct spi_board_info ek_spi_devices[] = {
   *	...
   *	{
   *		.modalias		= "rtc-pcf2123",
   *		.chip_select		= 1,
   *		.controller_data	= (void *)AT91_PIN_PA10,
   *		.max_speed_hz		= 1000 * 1000,
   *		.mode			= SPI_CS_HIGH,
   *		.bus_num		= 0,
   *	},
   *	...
   *};
   *
   */
  
  #include <linux/bcd.h>
  #include <linux/delay.h>
  #include <linux/device.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  #include <linux/rtc.h>
  #include <linux/spi/spi.h>
  #include <linux/module.h>
  #include <linux/sysfs.h>
  
  #define DRV_VERSION "0.6"
  
  #define PCF2123_REG_CTRL1	(0x00)	/* Control Register 1 */
  #define PCF2123_REG_CTRL2	(0x01)	/* Control Register 2 */
  #define PCF2123_REG_SC		(0x02)	/* datetime */
  #define PCF2123_REG_MN		(0x03)
  #define PCF2123_REG_HR		(0x04)
  #define PCF2123_REG_DM		(0x05)
  #define PCF2123_REG_DW		(0x06)
  #define PCF2123_REG_MO		(0x07)
  #define PCF2123_REG_YR		(0x08)
  
  #define PCF2123_SUBADDR		(1 << 4)
  #define PCF2123_WRITE		((0 << 7) | PCF2123_SUBADDR)
  #define PCF2123_READ		((1 << 7) | PCF2123_SUBADDR)
  
  static struct spi_driver pcf2123_driver;
  
  struct pcf2123_sysfs_reg {
  	struct device_attribute attr;
  	char name[2];
  };
  
  struct pcf2123_plat_data {
  	struct rtc_device *rtc;
  	struct pcf2123_sysfs_reg regs[16];
  };
  
  /*
   * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
   * is released properly after an SPI write.  This function should be
   * called after EVERY read/write call over SPI.
   */
  static inline void pcf2123_delay_trec(void)
  {
  	ndelay(30);
  }
  
  static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
  			    char *buffer)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	struct pcf2123_sysfs_reg *r;
  	u8 txbuf[1], rxbuf[1];
  	unsigned long reg;
  	int ret;
  
  	r = container_of(attr, struct pcf2123_sysfs_reg, attr);
  
  	ret = kstrtoul(r->name, 16, &reg);
  	if (ret)
  		return ret;
  
  	txbuf[0] = PCF2123_READ | reg;
  	ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
  	if (ret < 0)
  		return -EIO;
  	pcf2123_delay_trec();
  	return sprintf(buffer, "0x%x
  ", rxbuf[0]);
  }
  
  static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
  			     const char *buffer, size_t count) {
  	struct spi_device *spi = to_spi_device(dev);
  	struct pcf2123_sysfs_reg *r;
  	u8 txbuf[2];
  	unsigned long reg;
  	unsigned long val;
  
  	int ret;
  
  	r = container_of(attr, struct pcf2123_sysfs_reg, attr);
  
  	ret = kstrtoul(r->name, 16, &reg);
  	if (ret)
  		return ret;
  
  	ret = kstrtoul(buffer, 10, &val);
  	if (ret)
  		return ret;
  
  	txbuf[0] = PCF2123_WRITE | reg;
  	txbuf[1] = val;
  	ret = spi_write(spi, txbuf, sizeof(txbuf));
  	if (ret < 0)
  		return -EIO;
  	pcf2123_delay_trec();
  	return count;
  }
  
  static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	u8 txbuf[1], rxbuf[7];
  	int ret;
  
  	txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
  	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
  			rxbuf, sizeof(rxbuf));
  	if (ret < 0)
  		return ret;
  	pcf2123_delay_trec();
  
  	tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
  	tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
  	tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
  	tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
  	tm->tm_wday = rxbuf[4] & 0x07;
  	tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
  	tm->tm_year = bcd2bin(rxbuf[6]);
  	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
  ",
  			__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(dev, "retrieved date/time is not valid.
  ");
  
  	return 0;
  }
  
  static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	u8 txbuf[8];
  	int ret;
  
  	dev_dbg(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);
  
  	/* Stop the counter first */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
  	txbuf[1] = 0x20;
  	ret = spi_write(spi, txbuf, 2);
  	if (ret < 0)
  		return ret;
  	pcf2123_delay_trec();
  
  	/* Set the new time */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
  	txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
  	txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
  	txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
  	txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
  	txbuf[5] = tm->tm_wday & 0x07;
  	txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
  	txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
  
  	ret = spi_write(spi, txbuf, sizeof(txbuf));
  	if (ret < 0)
  		return ret;
  	pcf2123_delay_trec();
  
  	/* Start the counter */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
  	txbuf[1] = 0x00;
  	ret = spi_write(spi, txbuf, 2);
  	if (ret < 0)
  		return ret;
  	pcf2123_delay_trec();
  
  	return 0;
  }
  
  static const struct rtc_class_ops pcf2123_rtc_ops = {
  	.read_time	= pcf2123_rtc_read_time,
  	.set_time	= pcf2123_rtc_set_time,
  };
  
  static int pcf2123_probe(struct spi_device *spi)
  {
  	struct rtc_device *rtc;
  	struct pcf2123_plat_data *pdata;
  	u8 txbuf[2], rxbuf[2];
  	int ret, i;
  
  	pdata = devm_kzalloc(&spi->dev, sizeof(struct pcf2123_plat_data),
  				GFP_KERNEL);
  	if (!pdata)
  		return -ENOMEM;
  	spi->dev.platform_data = pdata;
  
  	/* Send a software reset command */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
  	txbuf[1] = 0x58;
  	dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)
  ",
  			txbuf[0], txbuf[1]);
  	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
  	if (ret < 0)
  		goto kfree_exit;
  	pcf2123_delay_trec();
  
  	/* Stop the counter */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
  	txbuf[1] = 0x20;
  	dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)
  ",
  			txbuf[0], txbuf[1]);
  	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
  	if (ret < 0)
  		goto kfree_exit;
  	pcf2123_delay_trec();
  
  	/* See if the counter was actually stopped */
  	txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
  	dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)
  ",
  			txbuf[0]);
  	ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
  					rxbuf, 2 * sizeof(u8));
  	dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)
  ",
  			rxbuf[0], rxbuf[1]);
  	if (ret < 0)
  		goto kfree_exit;
  	pcf2123_delay_trec();
  
  	if (!(rxbuf[0] & 0x20)) {
  		dev_err(&spi->dev, "chip not found
  ");
  		ret = -ENODEV;
  		goto kfree_exit;
  	}
  
  	dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "
  ");
  	dev_info(&spi->dev, "spiclk %u KHz.
  ",
  			(spi->max_speed_hz + 500) / 1000);
  
  	/* Start the counter */
  	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
  	txbuf[1] = 0x00;
  	ret = spi_write(spi, txbuf, sizeof(txbuf));
  	if (ret < 0)
  		goto kfree_exit;
  	pcf2123_delay_trec();
  
  	/* Finalize the initialization */
  	rtc = devm_rtc_device_register(&spi->dev, pcf2123_driver.driver.name,
  			&pcf2123_rtc_ops, THIS_MODULE);
  
  	if (IS_ERR(rtc)) {
  		dev_err(&spi->dev, "failed to register.
  ");
  		ret = PTR_ERR(rtc);
  		goto kfree_exit;
  	}
  
  	pdata->rtc = rtc;
  
  	for (i = 0; i < 16; i++) {
  		sysfs_attr_init(&pdata->regs[i].attr.attr);
  		sprintf(pdata->regs[i].name, "%1x", i);
  		pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
  		pdata->regs[i].attr.attr.name = pdata->regs[i].name;
  		pdata->regs[i].attr.show = pcf2123_show;
  		pdata->regs[i].attr.store = pcf2123_store;
  		ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
  		if (ret) {
  			dev_err(&spi->dev, "Unable to create sysfs %s
  ",
  				pdata->regs[i].name);
  			goto sysfs_exit;
  		}
  	}
  
  	return 0;
  
  sysfs_exit:
  	for (i--; i >= 0; i--)
  		device_remove_file(&spi->dev, &pdata->regs[i].attr);
  
  kfree_exit:
  	spi->dev.platform_data = NULL;
  	return ret;
  }
  
  static int pcf2123_remove(struct spi_device *spi)
  {
  	struct pcf2123_plat_data *pdata = dev_get_platdata(&spi->dev);
  	int i;
  
  	if (pdata) {
  		for (i = 0; i < 16; i++)
  			if (pdata->regs[i].name[0])
  				device_remove_file(&spi->dev,
  						   &pdata->regs[i].attr);
  	}
  
  	return 0;
  }
  
  static struct spi_driver pcf2123_driver = {
  	.driver	= {
  			.name	= "rtc-pcf2123",
  			.owner	= THIS_MODULE,
  	},
  	.probe	= pcf2123_probe,
  	.remove	= pcf2123_remove,
  };
  
  module_spi_driver(pcf2123_driver);
  
  MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
  MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);