// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * DS1286 Real Time Clock interface for Linux
   *
   * Copyright (C) 1998, 1999, 2000 Ralf Baechle
   * Copyright (C) 2008 Thomas Bogendoerfer
   *
   * Based on code written by Paul Gortmaker.

   */
  
  #include <linux/module.h>
  #include <linux/rtc.h>
  #include <linux/platform_device.h>
  #include <linux/bcd.h>

  #include <linux/rtc/ds1286.h>

  #include <linux/io.h>

  #include <linux/slab.h>

  struct ds1286_priv {
  	struct rtc_device *rtc;
  	u32 __iomem *rtcregs;

  	spinlock_t lock;
  };
  
  static inline u8 ds1286_rtc_read(struct ds1286_priv *priv, int reg)
  {
  	return __raw_readl(&priv->rtcregs[reg]) & 0xff;
  }
  
  static inline void ds1286_rtc_write(struct ds1286_priv *priv, u8 data, int reg)
  {
  	__raw_writel(data, &priv->rtcregs[reg]);
  }

  
  static int ds1286_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned long flags;
  	unsigned char val;
  
  	/* Allow or mask alarm interrupts */
  	spin_lock_irqsave(&priv->lock, flags);
  	val = ds1286_rtc_read(priv, RTC_CMD);
  	if (enabled)
  		val &=  ~RTC_TDM;
  	else
  		val |=  RTC_TDM;
  	ds1286_rtc_write(priv, val, RTC_CMD);
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	return 0;
  }

  #ifdef CONFIG_RTC_INTF_DEV
  
  static int ds1286_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned long flags;
  	unsigned char val;
  
  	switch (cmd) {

  	case RTC_WIE_OFF:
  		/* Mask watchdog int. enab. bit	*/
  		spin_lock_irqsave(&priv->lock, flags);
  		val = ds1286_rtc_read(priv, RTC_CMD);
  		val |= RTC_WAM;
  		ds1286_rtc_write(priv, val, RTC_CMD);
  		spin_unlock_irqrestore(&priv->lock, flags);
  		break;
  	case RTC_WIE_ON:
  		/* Allow watchdog interrupts.	*/
  		spin_lock_irqsave(&priv->lock, flags);
  		val = ds1286_rtc_read(priv, RTC_CMD);
  		val &= ~RTC_WAM;
  		ds1286_rtc_write(priv, val, RTC_CMD);
  		spin_unlock_irqrestore(&priv->lock, flags);
  		break;
  	default:
  		return -ENOIOCTLCMD;
  	}
  	return 0;
  }
  
  #else
  #define ds1286_ioctl    NULL
  #endif
  
  #ifdef CONFIG_PROC_FS
  
  static int ds1286_proc(struct device *dev, struct seq_file *seq)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned char month, cmd, amode;
  	const char *s;
  
  	month = ds1286_rtc_read(priv, RTC_MONTH);
  	seq_printf(seq,
  		   "oscillator\t: %s
  "
  		   "square_wave\t: %s
  ",
  		   (month & RTC_EOSC) ? "disabled" : "enabled",
  		   (month & RTC_ESQW) ? "disabled" : "enabled");
  
  	amode = ((ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x80) >> 5) |
  		((ds1286_rtc_read(priv, RTC_HOURS_ALARM) & 0x80) >> 6) |
  		((ds1286_rtc_read(priv, RTC_DAY_ALARM) & 0x80) >> 7);
  	switch (amode) {
  	case 7:
  		s = "each minute";
  		break;
  	case 3:
  		s = "minutes match";
  		break;
  	case 1:
  		s = "hours and minutes match";
  		break;
  	case 0:
  		s = "days, hours and minutes match";
  		break;
  	default:
  		s = "invalid";
  		break;
  	}
  	seq_printf(seq, "alarm_mode\t: %s
  ", s);
  
  	cmd = ds1286_rtc_read(priv, RTC_CMD);
  	seq_printf(seq,
  		   "alarm_enable\t: %s
  "
  		   "wdog_alarm\t: %s
  "
  		   "alarm_mask\t: %s
  "
  		   "wdog_alarm_mask\t: %s
  "
  		   "interrupt_mode\t: %s
  "
  		   "INTB_mode\t: %s_active
  "
  		   "interrupt_pins\t: %s
  ",
  		   (cmd & RTC_TDF) ? "yes" : "no",
  		   (cmd & RTC_WAF) ? "yes" : "no",
  		   (cmd & RTC_TDM) ? "disabled" : "enabled",
  		   (cmd & RTC_WAM) ? "disabled" : "enabled",
  		   (cmd & RTC_PU_LVL) ? "pulse" : "level",
  		   (cmd & RTC_IBH_LO) ? "low" : "high",
  		   (cmd & RTC_IPSW) ? "unswapped" : "swapped");
  	return 0;
  }
  
  #else
  #define ds1286_proc     NULL
  #endif
  
  static int ds1286_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned char save_control;
  	unsigned long flags;
  	unsigned long uip_watchdog = jiffies;
  
  	/*
  	 * read RTC once any update in progress is done. The update
  	 * can take just over 2ms. We wait 10 to 20ms. There is no need to
  	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
  	 * If you need to know *exactly* when a second has started, enable
  	 * periodic update complete interrupts, (via ioctl) and then
  	 * immediately read /dev/rtc which will block until you get the IRQ.
  	 * Once the read clears, read the RTC time (again via ioctl). Easy.
  	 */
  
  	if (ds1286_rtc_read(priv, RTC_CMD) & RTC_TE)
  		while (time_before(jiffies, uip_watchdog + 2*HZ/100))
  			barrier();
  
  	/*
  	 * Only the values that we read from the RTC are set. We leave
  	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
  	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
  	 * by the RTC when initially set to a non-zero value.
  	 */
  	spin_lock_irqsave(&priv->lock, flags);
  	save_control = ds1286_rtc_read(priv, RTC_CMD);
  	ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);
  
  	tm->tm_sec = ds1286_rtc_read(priv, RTC_SECONDS);
  	tm->tm_min = ds1286_rtc_read(priv, RTC_MINUTES);
  	tm->tm_hour = ds1286_rtc_read(priv, RTC_HOURS) & 0x3f;
  	tm->tm_mday = ds1286_rtc_read(priv, RTC_DATE);
  	tm->tm_mon = ds1286_rtc_read(priv, RTC_MONTH) & 0x1f;
  	tm->tm_year = ds1286_rtc_read(priv, RTC_YEAR);
  
  	ds1286_rtc_write(priv, save_control, RTC_CMD);
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	tm->tm_sec = bcd2bin(tm->tm_sec);
  	tm->tm_min = bcd2bin(tm->tm_min);
  	tm->tm_hour = bcd2bin(tm->tm_hour);
  	tm->tm_mday = bcd2bin(tm->tm_mday);
  	tm->tm_mon = bcd2bin(tm->tm_mon);
  	tm->tm_year = bcd2bin(tm->tm_year);
  
  	/*
  	 * Account for differences between how the RTC uses the values
  	 * and how they are defined in a struct rtc_time;
  	 */
  	if (tm->tm_year < 45)
  		tm->tm_year += 30;
  	tm->tm_year += 40;
  	if (tm->tm_year < 70)
  		tm->tm_year += 100;
  
  	tm->tm_mon--;

  	return 0;

  }
  
  static int ds1286_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned char mon, day, hrs, min, sec;
  	unsigned char save_control;
  	unsigned int yrs;
  	unsigned long flags;
  
  	yrs = tm->tm_year + 1900;
  	mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
  	day = tm->tm_mday;
  	hrs = tm->tm_hour;
  	min = tm->tm_min;
  	sec = tm->tm_sec;
  
  	if (yrs < 1970)
  		return -EINVAL;
  
  	yrs -= 1940;
  	if (yrs > 255)    /* They are unsigned */
  		return -EINVAL;
  
  	if (yrs >= 100)
  		yrs -= 100;
  
  	sec = bin2bcd(sec);
  	min = bin2bcd(min);
  	hrs = bin2bcd(hrs);
  	day = bin2bcd(day);
  	mon = bin2bcd(mon);
  	yrs = bin2bcd(yrs);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	save_control = ds1286_rtc_read(priv, RTC_CMD);
  	ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);
  
  	ds1286_rtc_write(priv, yrs, RTC_YEAR);
  	ds1286_rtc_write(priv, mon, RTC_MONTH);
  	ds1286_rtc_write(priv, day, RTC_DATE);
  	ds1286_rtc_write(priv, hrs, RTC_HOURS);
  	ds1286_rtc_write(priv, min, RTC_MINUTES);
  	ds1286_rtc_write(priv, sec, RTC_SECONDS);
  	ds1286_rtc_write(priv, 0, RTC_HUNDREDTH_SECOND);
  
  	ds1286_rtc_write(priv, save_control, RTC_CMD);
  	spin_unlock_irqrestore(&priv->lock, flags);
  	return 0;
  }
  
  static int ds1286_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);

  	unsigned long flags;
  
  	/*
  	 * Only the values that we read from the RTC are set. That
  	 * means only tm_wday, tm_hour, tm_min.
  	 */
  	spin_lock_irqsave(&priv->lock, flags);
  	alm->time.tm_min = ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x7f;
  	alm->time.tm_hour = ds1286_rtc_read(priv, RTC_HOURS_ALARM)  & 0x1f;
  	alm->time.tm_wday = ds1286_rtc_read(priv, RTC_DAY_ALARM)    & 0x07;

  	ds1286_rtc_read(priv, RTC_CMD);

  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	alm->time.tm_min = bcd2bin(alm->time.tm_min);
  	alm->time.tm_hour = bcd2bin(alm->time.tm_hour);
  	alm->time.tm_sec = 0;
  	return 0;
  }
  
  static int ds1286_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct ds1286_priv *priv = dev_get_drvdata(dev);
  	unsigned char hrs, min, sec;
  
  	hrs = alm->time.tm_hour;
  	min = alm->time.tm_min;
  	sec = alm->time.tm_sec;
  
  	if (hrs >= 24)
  		hrs = 0xff;
  
  	if (min >= 60)
  		min = 0xff;
  
  	if (sec != 0)
  		return -EINVAL;
  
  	min = bin2bcd(min);
  	hrs = bin2bcd(hrs);
  
  	spin_lock(&priv->lock);
  	ds1286_rtc_write(priv, hrs, RTC_HOURS_ALARM);
  	ds1286_rtc_write(priv, min, RTC_MINUTES_ALARM);
  	spin_unlock(&priv->lock);
  
  	return 0;
  }
  
  static const struct rtc_class_ops ds1286_ops = {

  	.ioctl		= ds1286_ioctl,
  	.proc		= ds1286_proc,

  	.read_time	= ds1286_read_time,
  	.set_time	= ds1286_set_time,
  	.read_alarm	= ds1286_read_alarm,
  	.set_alarm	= ds1286_set_alarm,

  	.alarm_irq_enable = ds1286_alarm_irq_enable,

  };

  static int ds1286_probe(struct platform_device *pdev)

  {
  	struct rtc_device *rtc;

  	struct ds1286_priv *priv;

  	priv = devm_kzalloc(&pdev->dev, sizeof(struct ds1286_priv), GFP_KERNEL);

  	if (!priv)
  		return -ENOMEM;

  	priv->rtcregs = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(priv->rtcregs))
  		return PTR_ERR(priv->rtcregs);

  	spin_lock_init(&priv->lock);

  	platform_set_drvdata(pdev, priv);

  	rtc = devm_rtc_device_register(&pdev->dev, "ds1286", &ds1286_ops,
  					THIS_MODULE);
  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);

  	priv->rtc = rtc;

  	return 0;

  }

  static struct platform_driver ds1286_platform_driver = {
  	.driver		= {
  		.name	= "rtc-ds1286",

  	},
  	.probe		= ds1286_probe,

  };

  module_platform_driver(ds1286_platform_driver);

  
  MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
  MODULE_DESCRIPTION("DS1286 RTC driver");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:rtc-ds1286");