// 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\n"
		   "square_wave\t: %s\n",
		   (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\n", s);

	cmd = ds1286_rtc_read(priv, RTC_CMD);
	seq_printf(seq,
		   "alarm_enable\t: %s\n"
		   "wdog_alarm\t: %s\n"
		   "alarm_mask\t: %s\n"
		   "wdog_alarm_mask\t: %s\n"
		   "interrupt_mode\t: %s\n"
		   "INTB_mode\t: %s_active\n"
		   "interrupt_pins\t: %s\n",
		   (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");