text: /*
   * RTC class driver for "CMOS RTC":  PCs, ACPI, etc
   *
   * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
   * Copyright (C) 2006 David Brownell (convert to new framework)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  /*
   * The original "cmos clock" chip was an MC146818 chip, now obsolete.
   * That defined the register interface now provided by all PCs, some
   * non-PC systems, and incorporated into ACPI.  Modern PC chipsets
   * integrate an MC146818 clone in their southbridge, and boards use
   * that instead of discrete clones like the DS12887 or M48T86.  There
   * are also clones that connect using the LPC bus.
   *
   * That register API is also used directly by various other drivers
   * (notably for integrated NVRAM), infrastructure (x86 has code to
   * bypass the RTC framework, directly reading the RTC during boot
   * and updating minutes/seconds for systems using NTP synch) and
   * utilities (like userspace 'hwclock', if no /dev node exists).
   *
   * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with
   * interrupts disabled, holding the global rtc_lock, to exclude those
   * other drivers and utilities on correctly configured systems.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/spinlock.h>
  #include <linux/platform_device.h>
  #include <linux/log2.h>
  #include <linux/pm.h>
  #include <linux/of.h>
  #include <linux/of_platform.h>
  #include <linux/dmi.h>
  
  /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
  #include <asm-generic/rtc.h>
  
  struct cmos_rtc {
  	struct rtc_device	*rtc;
  	struct device		*dev;
  	int			irq;
  	struct resource		*iomem;
  
  	void			(*wake_on)(struct device *);
  	void			(*wake_off)(struct device *);
  
  	u8			enabled_wake;
  	u8			suspend_ctrl;
  
  	/* newer hardware extends the original register set */
  	u8			day_alrm;
  	u8			mon_alrm;
  	u8			century;
  };
  
  /* both platform and pnp busses use negative numbers for invalid irqs */
  #define is_valid_irq(n)		((n) > 0)
  
  static const char driver_name[] = "rtc_cmos";
  
  /* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
   * always mask it against the irq enable bits in RTC_CONTROL.  Bit values
   * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
   */
  #define	RTC_IRQMASK	(RTC_PF | RTC_AF | RTC_UF)
  
  static inline int is_intr(u8 rtc_intr)
  {
  	if (!(rtc_intr & RTC_IRQF))
  		return 0;
  	return rtc_intr & RTC_IRQMASK;
  }
  
  /*----------------------------------------------------------------*/
  
  /* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
   * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
   * used in a broken "legacy replacement" mode.  The breakage includes
   * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
   * other (better) use.
   *
   * When that broken mode is in use, platform glue provides a partial
   * emulation of hardware RTC IRQ facilities using HPET #1.  We don't
   * want to use HPET for anything except those IRQs though...
   */
  #ifdef CONFIG_HPET_EMULATE_RTC
  #include <asm/hpet.h>
  #else
  
  static inline int is_hpet_enabled(void)
  {
  	return 0;
  }
  
  static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
  {
  	return 0;
  }
  
  static inline int hpet_set_rtc_irq_bit(unsigned long mask)
  {
  	return 0;
  }
  
  static inline int
  hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
  {
  	return 0;
  }
  
  static inline int hpet_set_periodic_freq(unsigned long freq)
  {
  	return 0;
  }
  
  static inline int hpet_rtc_dropped_irq(void)
  {
  	return 0;
  }
  
  static inline int hpet_rtc_timer_init(void)
  {
  	return 0;
  }
  
  extern irq_handler_t hpet_rtc_interrupt;
  
  static inline int hpet_register_irq_handler(irq_handler_t handler)
  {
  	return 0;
  }
  
  static inline int hpet_unregister_irq_handler(irq_handler_t handler)
  {
  	return 0;
  }
  
  #endif
  
  /*----------------------------------------------------------------*/
  
  #ifdef RTC_PORT
  
  /* Most newer x86 systems have two register banks, the first used
   * for RTC and NVRAM and the second only for NVRAM.  Caller must
   * own rtc_lock ... and we won't worry about access during NMI.
   */
  #define can_bank2	true
  
  static inline unsigned char cmos_read_bank2(unsigned char addr)
  {
  	outb(addr, RTC_PORT(2));
  	return inb(RTC_PORT(3));
  }
  
  static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
  {
  	outb(addr, RTC_PORT(2));
  	outb(val, RTC_PORT(3));
  }
  
  #else
  
  #define can_bank2	false
  
  static inline unsigned char cmos_read_bank2(unsigned char addr)
  {
  	return 0;
  }
  
  static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
  {
  }
  
  #endif
  
  /*----------------------------------------------------------------*/
  
  static int cmos_read_time(struct device *dev, struct rtc_time *t)
  {
  	/* REVISIT:  if the clock has a "century" register, use
  	 * that instead of the heuristic in get_rtc_time().
  	 * That'll make Y3K compatility (year > 2070) easy!
  	 */
  	get_rtc_time(t);
  	return 0;
  }
  
  static int cmos_set_time(struct device *dev, struct rtc_time *t)
  {
  	/* REVISIT:  set the "century" register if available
  	 *
  	 * NOTE: this ignores the issue whereby updating the seconds
  	 * takes effect exactly 500ms after we write the register.
  	 * (Also queueing and other delays before we get this far.)
  	 */
  	return set_rtc_time(t);
  }
  
  static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned char	rtc_control;
  
  	if (!is_valid_irq(cmos->irq))
  		return -EIO;
  
  	/* Basic alarms only support hour, minute, and seconds fields.
  	 * Some also support day and month, for alarms up to a year in
  	 * the future.
  	 */
  	t->time.tm_mday = -1;
  	t->time.tm_mon = -1;
  
  	spin_lock_irq(&rtc_lock);
  	t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
  	t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
  	t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
  
  	if (cmos->day_alrm) {
  		/* ignore upper bits on readback per ACPI spec */
  		t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
  		if (!t->time.tm_mday)
  			t->time.tm_mday = -1;
  
  		if (cmos->mon_alrm) {
  			t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
  			if (!t->time.tm_mon)
  				t->time.tm_mon = -1;
  		}
  	}
  
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	spin_unlock_irq(&rtc_lock);
  
  	if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  		if (((unsigned)t->time.tm_sec) < 0x60)
  			t->time.tm_sec = bcd2bin(t->time.tm_sec);
  		else
  			t->time.tm_sec = -1;
  		if (((unsigned)t->time.tm_min) < 0x60)
  			t->time.tm_min = bcd2bin(t->time.tm_min);
  		else
  			t->time.tm_min = -1;
  		if (((unsigned)t->time.tm_hour) < 0x24)
  			t->time.tm_hour = bcd2bin(t->time.tm_hour);
  		else
  			t->time.tm_hour = -1;
  
  		if (cmos->day_alrm) {
  			if (((unsigned)t->time.tm_mday) <= 0x31)
  				t->time.tm_mday = bcd2bin(t->time.tm_mday);
  			else
  				t->time.tm_mday = -1;
  
  			if (cmos->mon_alrm) {
  				if (((unsigned)t->time.tm_mon) <= 0x12)
  					t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
  				else
  					t->time.tm_mon = -1;
  			}
  		}
  	}
  	t->time.tm_year = -1;
  
  	t->enabled = !!(rtc_control & RTC_AIE);
  	t->pending = 0;
  
  	return 0;
  }
  
  static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
  {
  	unsigned char	rtc_intr;
  
  	/* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
  	 * allegedly some older rtcs need that to handle irqs properly
  	 */
  	rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
  
  	if (is_hpet_enabled())
  		return;
  
  	rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
  	if (is_intr(rtc_intr))
  		rtc_update_irq(cmos->rtc, 1, rtc_intr);
  }
  
  static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
  {
  	unsigned char	rtc_control;
  
  	/* flush any pending IRQ status, notably for update irqs,
  	 * before we enable new IRQs
  	 */
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	cmos_checkintr(cmos, rtc_control);
  
  	rtc_control |= mask;
  	CMOS_WRITE(rtc_control, RTC_CONTROL);
  	hpet_set_rtc_irq_bit(mask);
  
  	cmos_checkintr(cmos, rtc_control);
  }
  
  static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
  {
  	unsigned char	rtc_control;
  
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	rtc_control &= ~mask;
  	CMOS_WRITE(rtc_control, RTC_CONTROL);
  	hpet_mask_rtc_irq_bit(mask);
  
  	cmos_checkintr(cmos, rtc_control);
  }
  
  static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned char mon, mday, hrs, min, sec, rtc_control;
  
  	if (!is_valid_irq(cmos->irq))
  		return -EIO;
  
  	mon = t->time.tm_mon + 1;
  	mday = t->time.tm_mday;
  	hrs = t->time.tm_hour;
  	min = t->time.tm_min;
  	sec = t->time.tm_sec;
  
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  		/* Writing 0xff means "don't care" or "match all".  */
  		mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
  		mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
  		hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
  		min = (min < 60) ? bin2bcd(min) : 0xff;
  		sec = (sec < 60) ? bin2bcd(sec) : 0xff;
  	}
  
  	spin_lock_irq(&rtc_lock);
  
  	/* next rtc irq must not be from previous alarm setting */
  	cmos_irq_disable(cmos, RTC_AIE);
  
  	/* update alarm */
  	CMOS_WRITE(hrs, RTC_HOURS_ALARM);
  	CMOS_WRITE(min, RTC_MINUTES_ALARM);
  	CMOS_WRITE(sec, RTC_SECONDS_ALARM);
  
  	/* the system may support an "enhanced" alarm */
  	if (cmos->day_alrm) {
  		CMOS_WRITE(mday, cmos->day_alrm);
  		if (cmos->mon_alrm)
  			CMOS_WRITE(mon, cmos->mon_alrm);
  	}
  
  	/* FIXME the HPET alarm glue currently ignores day_alrm
  	 * and mon_alrm ...
  	 */
  	hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
  
  	if (t->enabled)
  		cmos_irq_enable(cmos, RTC_AIE);
  
  	spin_unlock_irq(&rtc_lock);
  
  	return 0;
  }
  
  /*
   * Do not disable RTC alarm on shutdown - workaround for b0rked BIOSes.
   */
  static bool alarm_disable_quirk;
  
  static int __init set_alarm_disable_quirk(const struct dmi_system_id *id)
  {
  	alarm_disable_quirk = true;
  	pr_info("BIOS has alarm-disable quirk - RTC alarms disabled\n");
  	return 0;
  }
  
  static const struct dmi_system_id rtc_quirks[] __initconst = {
  	/* https://bugzilla.novell.com/show_bug.cgi?id=805740 */
  	{
  		.callback = set_alarm_disable_quirk,
  		.ident    = "IBM Truman",
  		.matches  = {
  			DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
  			DMI_MATCH(DMI_PRODUCT_NAME, "4852570"),
  		},
  	},
  	/* https://bugzilla.novell.com/show_bug.cgi?id=812592 */
  	{
  		.callback = set_alarm_disable_quirk,
  		.ident    = "Gigabyte GA-990XA-UD3",
  		.matches  = {
  			DMI_MATCH(DMI_SYS_VENDOR,
  					"Gigabyte Technology Co., Ltd."),
  			DMI_MATCH(DMI_PRODUCT_NAME, "GA-990XA-UD3"),
  		},
  	},
  	/* http://permalink.gmane.org/gmane.linux.kernel/1604474 */
  	{
  		.callback = set_alarm_disable_quirk,
  		.ident    = "Toshiba Satellite L300",
  		.matches  = {
  			DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
  			DMI_MATCH(DMI_PRODUCT_NAME, "Satellite L300"),
  		},
  	},
  	{}
  };
  
  static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned long	flags;
  
  	if (!is_valid_irq(cmos->irq))
  		return -EINVAL;
  
  	if (alarm_disable_quirk)
  		return 0;
  
  	spin_lock_irqsave(&rtc_lock, flags);
  
  	if (enabled)
  		cmos_irq_enable(cmos, RTC_AIE);
  	else
  		cmos_irq_disable(cmos, RTC_AIE);
  
  	spin_unlock_irqrestore(&rtc_lock, flags);
  	return 0;
  }
  
  #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
  
  static int cmos_procfs(struct device *dev, struct seq_file *seq)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned char	rtc_control, valid;
  
  	spin_lock_irq(&rtc_lock);
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	valid = CMOS_READ(RTC_VALID);
  	spin_unlock_irq(&rtc_lock);
  
  	/* NOTE:  at least ICH6 reports battery status using a different
  	 * (non-RTC) bit; and SQWE is ignored on many current systems.
  	 */
  	seq_printf(seq,
  		   "periodic_IRQ\t: %s\n"
  		   "update_IRQ\t: %s\n"
  		   "HPET_emulated\t: %s\n"
  		   // "square_wave\t: %s\n"
  		   "BCD\t\t: %s\n"
  		   "DST_enable\t: %s\n"
  		   "periodic_freq\t: %d\n"
  		   "batt_status\t: %s\n",
  		   (rtc_control & RTC_PIE) ? "yes" : "no",
  		   (rtc_control & RTC_UIE) ? "yes" : "no",
  		   is_hpet_enabled() ? "yes" : "no",
  		   // (rtc_control & RTC_SQWE) ? "yes" : "no",
  		   (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
  		   (rtc_control & RTC_DST_EN) ? "yes" : "no",
  		   cmos->rtc->irq_freq,
  		   (valid & RTC_VRT) ? "okay" : "dead");
  
  	return 0;
  }
  
  #else
  #define	cmos_procfs	NULL
  #endif
  
  static const struct rtc_class_ops cmos_rtc_ops = {
  	.read_time		= cmos_read_time,
  	.set_time		= cmos_set_time,
  	.read_alarm		= cmos_read_alarm,
  	.set_alarm		= cmos_set_alarm,
  	.proc			= cmos_procfs,
  	.alarm_irq_enable	= cmos_alarm_irq_enable,
  };
  
  /*----------------------------------------------------------------*/
  
  /*
   * All these chips have at least 64 bytes of address space, shared by
   * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
   * by boot firmware.  Modern chips have 128 or 256 bytes.
   */
  
  #define NVRAM_OFFSET	(RTC_REG_D + 1)
  
  static ssize_t
  cmos_nvram_read(struct file *filp, struct kobject *kobj,
  		struct bin_attribute *attr,
  		char *buf, loff_t off, size_t count)
  {
  	int	retval;
  
  	if (unlikely(off >= attr->size))
  		return 0;
  	if (unlikely(off < 0))
  		return -EINVAL;
  	if ((off + count) > attr->size)
  		count = attr->size - off;
  
  	off += NVRAM_OFFSET;
  	spin_lock_irq(&rtc_lock);
  	for (retval = 0; count; count--, off++, retval++) {
  		if (off < 128)
  			*buf++ = CMOS_READ(off);
  		else if (can_bank2)
  			*buf++ = cmos_read_bank2(off);
  		else
  			break;
  	}
  	spin_unlock_irq(&rtc_lock);
  
  	return retval;
  }
  
  static ssize_t
  cmos_nvram_write(struct file *filp, struct kobject *kobj,
  		struct bin_attribute *attr,
  		char *buf, loff_t off, size_t count)
  {
  	struct cmos_rtc	*cmos;
  	int		retval;
  
  	cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
  	if (unlikely(off >= attr->size))
  		return -EFBIG;
  	if (unlikely(off < 0))
  		return -EINVAL;
  	if ((off + count) > attr->size)
  		count = attr->size - off;
  
  	/* NOTE:  on at least PCs and Ataris, the boot firmware uses a
  	 * checksum on part of the NVRAM data.  That's currently ignored
  	 * here.  If userspace is smart enough to know what fields of
  	 * NVRAM to update, updating checksums is also part of its job.
  	 */
  	off += NVRAM_OFFSET;
  	spin_lock_irq(&rtc_lock);
  	for (retval = 0; count; count--, off++, retval++) {
  		/* don't trash RTC registers */
  		if (off == cmos->day_alrm
  				|| off == cmos->mon_alrm
  				|| off == cmos->century)
  			buf++;
  		else if (off < 128)
  			CMOS_WRITE(*buf++, off);
  		else if (can_bank2)
  			cmos_write_bank2(*buf++, off);
  		else
  			break;
  	}
  	spin_unlock_irq(&rtc_lock);
  
  	return retval;
  }
  
  static struct bin_attribute nvram = {
  	.attr = {
  		.name	= "nvram",
  		.mode	= S_IRUGO | S_IWUSR,
  	},
  
  	.read	= cmos_nvram_read,
  	.write	= cmos_nvram_write,
  	/* size gets set up later */
  };
  
  /*----------------------------------------------------------------*/
  
  static struct cmos_rtc	cmos_rtc;
  
  static irqreturn_t cmos_interrupt(int irq, void *p)
  {
  	u8		irqstat;
  	u8		rtc_control;
  
  	spin_lock(&rtc_lock);
  
  	/* When the HPET interrupt handler calls us, the interrupt
  	 * status is passed as arg1 instead of the irq number.  But
  	 * always clear irq status, even when HPET is in the way.
  	 *
  	 * Note that HPET and RTC are almost certainly out of phase,
  	 * giving different IRQ status ...
  	 */
  	irqstat = CMOS_READ(RTC_INTR_FLAGS);
  	rtc_control = CMOS_READ(RTC_CONTROL);
  	if (is_hpet_enabled())
  		irqstat = (unsigned long)irq & 0xF0;
  
  	/* If we were suspended, RTC_CONTROL may not be accurate since the
  	 * bios may have cleared it.
  	 */
  	if (!cmos_rtc.suspend_ctrl)
  		irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
  	else
  		irqstat &= (cmos_rtc.suspend_ctrl & RTC_IRQMASK) | RTC_IRQF;
  
  	/* All Linux RTC alarms should be treated as if they were oneshot.
  	 * Similar code may be needed in system wakeup paths, in case the
  	 * alarm woke the system.
  	 */
  	if (irqstat & RTC_AIE) {
  		cmos_rtc.suspend_ctrl &= ~RTC_AIE;
  		rtc_control &= ~RTC_AIE;
  		CMOS_WRITE(rtc_control, RTC_CONTROL);
  		hpet_mask_rtc_irq_bit(RTC_AIE);
  		CMOS_READ(RTC_INTR_FLAGS);
  	}
  	spin_unlock(&rtc_lock);
  
  	if (is_intr(irqstat)) {
  		rtc_update_irq(p, 1, irqstat);
  		return IRQ_HANDLED;
  	} else
  		return IRQ_NONE;
  }
  
  #ifdef	CONFIG_PNP
  #define	INITSECTION
  
  #else
  #define	INITSECTION	__init
  #endif
  
  static int INITSECTION
  cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
  {
  	struct cmos_rtc_board_info	*info = dev_get_platdata(dev);
  	int				retval = 0;
  	unsigned char			rtc_control;
  	unsigned			address_space;
  	u32				flags = 0;
  
  	/* there can be only one ... */
  	if (cmos_rtc.dev)
  		return -EBUSY;
  
  	if (!ports)
  		return -ENODEV;
  
  	/* Claim I/O ports ASAP, minimizing conflict with legacy driver.
  	 *
  	 * REVISIT non-x86 systems may instead use memory space resources
  	 * (needing ioremap etc), not i/o space resources like this ...
  	 */
  	if (RTC_IOMAPPED)
  		ports = request_region(ports->start, resource_size(ports),
  				       driver_name);
  	else
  		ports = request_mem_region(ports->start, resource_size(ports),
  					   driver_name);
  	if (!ports) {
  		dev_dbg(dev, "i/o registers already in use\n");
  		return -EBUSY;
  	}
  
  	cmos_rtc.irq = rtc_irq;
  	cmos_rtc.iomem = ports;
  
  	/* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
  	 * driver did, but don't reject unknown configs.   Old hardware
  	 * won't address 128 bytes.  Newer chips have multiple banks,
  	 * though they may not be listed in one I/O resource.
  	 */
  #if	defined(CONFIG_ATARI)
  	address_space = 64;
  #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
  			|| defined(__sparc__) || defined(__mips__) \
  			|| defined(__powerpc__)
  	address_space = 128;
  #else
  #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
  	address_space = 128;
  #endif
  	if (can_bank2 && ports->end > (ports->start + 1))
  		address_space = 256;
  
  	/* For ACPI systems extension info comes from the FADT.  On others,
  	 * board specific setup provides it as appropriate.  Systems where
  	 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
  	 * some almost-clones) can provide hooks to make that behave.
  	 *
  	 * Note that ACPI doesn't preclude putting these registers into
  	 * "extended" areas of the chip, including some that we won't yet
  	 * expect CMOS_READ and friends to handle.
  	 */
  	if (info) {
  		if (info->flags)
  			flags = info->flags;
  		if (info->address_space)
  			address_space = info->address_space;
  
  		if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
  			cmos_rtc.day_alrm = info->rtc_day_alarm;
  		if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
  			cmos_rtc.mon_alrm = info->rtc_mon_alarm;
  		if (info->rtc_century && info->rtc_century < 128)
  			cmos_rtc.century = info->rtc_century;
  
  		if (info->wake_on && info->wake_off) {
  			cmos_rtc.wake_on = info->wake_on;
  			cmos_rtc.wake_off = info->wake_off;
  		}
  	}
  
  	cmos_rtc.dev = dev;
  	dev_set_drvdata(dev, &cmos_rtc);
  
  	cmos_rtc.rtc = rtc_device_register(driver_name, dev,
  				&cmos_rtc_ops, THIS_MODULE);
  	if (IS_ERR(cmos_rtc.rtc)) {
  		retval = PTR_ERR(cmos_rtc.rtc);
  		goto cleanup0;
  	}
  
  	rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
  
  	spin_lock_irq(&rtc_lock);
  
  	if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
  		/* force periodic irq to CMOS reset default of 1024Hz;
  		 *
  		 * REVISIT it's been reported that at least one x86_64 ALI
  		 * mobo doesn't use 32KHz here ... for portability we might
  		 * need to do something about other clock frequencies.
  		 */
  		cmos_rtc.rtc->irq_freq = 1024;
  		hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
  		CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
  	}
  
  	/* disable irqs */
  	if (is_valid_irq(rtc_irq))
  		cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
  
  	rtc_control = CMOS_READ(RTC_CONTROL);
  
  	spin_unlock_irq(&rtc_lock);
  
  	/* FIXME:
  	 * <asm-generic/rtc.h> doesn't know 12-hour mode either.
  	 */
  	if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
  		dev_warn(dev, "only 24-hr supported\n");
  		retval = -ENXIO;
  		goto cleanup1;
  	}
  
  	if (is_valid_irq(rtc_irq)) {
  		irq_handler_t rtc_cmos_int_handler;
  
  		if (is_hpet_enabled()) {
  			rtc_cmos_int_handler = hpet_rtc_interrupt;
  			retval = hpet_register_irq_handler(cmos_interrupt);
  			if (retval) {
  				dev_warn(dev, "hpet_register_irq_handler "
  						" failed in rtc_init().");
  				goto cleanup1;
  			}
  		} else
  			rtc_cmos_int_handler = cmos_interrupt;
  
  		retval = request_irq(rtc_irq, rtc_cmos_int_handler,
  				0, dev_name(&cmos_rtc.rtc->dev),
  				cmos_rtc.rtc);
  		if (retval < 0) {
  			dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
  			goto cleanup1;
  		}
  	}
  	hpet_rtc_timer_init();
  
  	/* export at least the first block of NVRAM */
  	nvram.size = address_space - NVRAM_OFFSET;
  	retval = sysfs_create_bin_file(&dev->kobj, &nvram);
  	if (retval < 0) {
  		dev_dbg(dev, "can't create nvram file? %d\n", retval);
  		goto cleanup2;
  	}
  
  	dev_info(dev, "%s%s, %zd bytes nvram%s\n",
  		!is_valid_irq(rtc_irq) ? "no alarms" :
  			cmos_rtc.mon_alrm ? "alarms up to one year" :
  			cmos_rtc.day_alrm ? "alarms up to one month" :
  			"alarms up to one day",
  		cmos_rtc.century ? ", y3k" : "",
  		nvram.size,
  		is_hpet_enabled() ? ", hpet irqs" : "");
  
  	return 0;
  
  cleanup2:
  	if (is_valid_irq(rtc_irq))
  		free_irq(rtc_irq, cmos_rtc.rtc);
  cleanup1:
  	cmos_rtc.dev = NULL;
  	rtc_device_unregister(cmos_rtc.rtc);
  cleanup0:
  	if (RTC_IOMAPPED)
  		release_region(ports->start, resource_size(ports));
  	else
  		release_mem_region(ports->start, resource_size(ports));
  	return retval;
  }
  
  static void cmos_do_shutdown(int rtc_irq)
  {
  	spin_lock_irq(&rtc_lock);
  	if (is_valid_irq(rtc_irq))
  		cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
  	spin_unlock_irq(&rtc_lock);
  }
  
  static void __exit cmos_do_remove(struct device *dev)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	struct resource *ports;
  
  	cmos_do_shutdown(cmos->irq);
  
  	sysfs_remove_bin_file(&dev->kobj, &nvram);
  
  	if (is_valid_irq(cmos->irq)) {
  		free_irq(cmos->irq, cmos->rtc);
  		hpet_unregister_irq_handler(cmos_interrupt);
  	}
  
  	rtc_device_unregister(cmos->rtc);
  	cmos->rtc = NULL;
  
  	ports = cmos->iomem;
  	if (RTC_IOMAPPED)
  		release_region(ports->start, resource_size(ports));
  	else
  		release_mem_region(ports->start, resource_size(ports));
  	cmos->iomem = NULL;
  
  	cmos->dev = NULL;
  }
  
  #ifdef CONFIG_PM
  
  static int cmos_suspend(struct device *dev)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned char	tmp;
  
  	/* only the alarm might be a wakeup event source */
  	spin_lock_irq(&rtc_lock);
  	cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
  	if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
  		unsigned char	mask;
  
  		if (device_may_wakeup(dev))
  			mask = RTC_IRQMASK & ~RTC_AIE;
  		else
  			mask = RTC_IRQMASK;
  		tmp &= ~mask;
  		CMOS_WRITE(tmp, RTC_CONTROL);
  		hpet_mask_rtc_irq_bit(mask);
  
  		cmos_checkintr(cmos, tmp);
  	}
  	spin_unlock_irq(&rtc_lock);
  
  	if (tmp & RTC_AIE) {
  		cmos->enabled_wake = 1;
  		if (cmos->wake_on)
  			cmos->wake_on(dev);
  		else
  			enable_irq_wake(cmos->irq);
  	}
  
  	dev_dbg(dev, "suspend%s, ctrl %02x\n",
  			(tmp & RTC_AIE) ? ", alarm may wake" : "",
  			tmp);
  
  	return 0;
  }
  
  /* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
   * after a detour through G3 "mechanical off", although the ACPI spec
   * says wakeup should only work from G1/S4 "hibernate".  To most users,
   * distinctions between S4 and S5 are pointless.  So when the hardware
   * allows, don't draw that distinction.
   */
  static inline int cmos_poweroff(struct device *dev)
  {
  	return cmos_suspend(dev);
  }
  
  #ifdef	CONFIG_PM_SLEEP
  
  static int cmos_resume(struct device *dev)
  {
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  	unsigned char tmp;
  
  	if (cmos->enabled_wake) {
  		if (cmos->wake_off)
  			cmos->wake_off(dev);
  		else
  			disable_irq_wake(cmos->irq);
  		cmos->enabled_wake = 0;
  	}
  
  	spin_lock_irq(&rtc_lock);
  	tmp = cmos->suspend_ctrl;
  	cmos->suspend_ctrl = 0;
  	/* re-enable any irqs previously active */
  	if (tmp & RTC_IRQMASK) {
  		unsigned char	mask;
  
  		if (device_may_wakeup(dev))
  			hpet_rtc_timer_init();
  
  		do {
  			CMOS_WRITE(tmp, RTC_CONTROL);
  			hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
  
  			mask = CMOS_READ(RTC_INTR_FLAGS);
  			mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
  			if (!is_hpet_enabled() || !is_intr(mask))
  				break;
  
  			/* force one-shot behavior if HPET blocked
  			 * the wake alarm's irq
  			 */
  			rtc_update_irq(cmos->rtc, 1, mask);
  			tmp &= ~RTC_AIE;
  			hpet_mask_rtc_irq_bit(RTC_AIE);
  		} while (mask & RTC_AIE);
  	}
  	spin_unlock_irq(&rtc_lock);
  
  	dev_dbg(dev, "resume, ctrl %02x\n", tmp);
  
  	return 0;
  }
  
  #endif
  #else
  
  static inline int cmos_poweroff(struct device *dev)
  {
  	return -ENOSYS;
  }
  
  #endif
  
  static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
  
  /*----------------------------------------------------------------*/
  
  /* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
   * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
   * probably list them in similar PNPBIOS tables; so PNP is more common.
   *
   * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
   * predate even PNPBIOS should set up platform_bus devices.
   */
  
  #ifdef	CONFIG_ACPI
  
  #include <linux/acpi.h>
  
  static u32 rtc_handler(void *context)
  {
  	struct device *dev = context;
  
  	pm_wakeup_event(dev, 0);
  	acpi_clear_event(ACPI_EVENT_RTC);
  	acpi_disable_event(ACPI_EVENT_RTC, 0);
  	return ACPI_INTERRUPT_HANDLED;
  }
  
  static inline void rtc_wake_setup(struct device *dev)
  {
  	acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
  	/*
  	 * After the RTC handler is installed, the Fixed_RTC event should
  	 * be disabled. Only when the RTC alarm is set will it be enabled.
  	 */
  	acpi_clear_event(ACPI_EVENT_RTC);
  	acpi_disable_event(ACPI_EVENT_RTC, 0);
  }
  
  static void rtc_wake_on(struct device *dev)
  {
  	acpi_clear_event(ACPI_EVENT_RTC);
  	acpi_enable_event(ACPI_EVENT_RTC, 0);
  }
  
  static void rtc_wake_off(struct device *dev)
  {
  	acpi_disable_event(ACPI_EVENT_RTC, 0);
  }
  
  /* Every ACPI platform has a mc146818 compatible "cmos rtc".  Here we find
   * its device node and pass extra config data.  This helps its driver use
   * capabilities that the now-obsolete mc146818 didn't have, and informs it
   * that this board's RTC is wakeup-capable (per ACPI spec).
   */
  static struct cmos_rtc_board_info acpi_rtc_info;
  
  static void cmos_wake_setup(struct device *dev)
  {
  	if (acpi_disabled)
  		return;
  
  	rtc_wake_setup(dev);
  	acpi_rtc_info.wake_on = rtc_wake_on;
  	acpi_rtc_info.wake_off = rtc_wake_off;
  
  	/* workaround bug in some ACPI tables */
  	if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
  		dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
  			acpi_gbl_FADT.month_alarm);
  		acpi_gbl_FADT.month_alarm = 0;
  	}
  
  	acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
  	acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
  	acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;
  
  	/* NOTE:  S4_RTC_WAKE is NOT currently useful to Linux */
  	if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
  		dev_info(dev, "RTC can wake from S4\n");
  
  	dev->platform_data = &acpi_rtc_info;
  
  	/* RTC always wakes from S1/S2/S3, and often S4/STD */
  	device_init_wakeup(dev, 1);
  }
  
  #else
  
  static void cmos_wake_setup(struct device *dev)
  {
  }
  
  #endif
  
  #ifdef	CONFIG_PNP
  
  #include <linux/pnp.h>
  
  static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
  {
  	cmos_wake_setup(&pnp->dev);
  
  	if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0))
  		/* Some machines contain a PNP entry for the RTC, but
  		 * don't define the IRQ. It should always be safe to
  		 * hardcode it in these cases
  		 */
  		return cmos_do_probe(&pnp->dev,
  				pnp_get_resource(pnp, IORESOURCE_IO, 0), 8);
  	else
  		return cmos_do_probe(&pnp->dev,
  				pnp_get_resource(pnp, IORESOURCE_IO, 0),
  				pnp_irq(pnp, 0));
  }
  
  static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
  {
  	cmos_do_remove(&pnp->dev);
  }
  
  static void cmos_pnp_shutdown(struct pnp_dev *pnp)
  {
  	struct device *dev = &pnp->dev;
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  
  	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(dev))
  		return;
  
  	cmos_do_shutdown(cmos->irq);
  }
  
  static const struct pnp_device_id rtc_ids[] = {
  	{ .id = "PNP0b00", },
  	{ .id = "PNP0b01", },
  	{ .id = "PNP0b02", },
  	{ },
  };
  MODULE_DEVICE_TABLE(pnp, rtc_ids);
  
  static struct pnp_driver cmos_pnp_driver = {
  	.name		= (char *) driver_name,
  	.id_table	= rtc_ids,
  	.probe		= cmos_pnp_probe,
  	.remove		= __exit_p(cmos_pnp_remove),
  	.shutdown	= cmos_pnp_shutdown,
  
  	/* flag ensures resume() gets called, and stops syslog spam */
  	.flags		= PNP_DRIVER_RES_DO_NOT_CHANGE,
  	.driver		= {
  			.pm = &cmos_pm_ops,
  	},
  };
  
  #endif	/* CONFIG_PNP */
  
  #ifdef CONFIG_OF
  static const struct of_device_id of_cmos_match[] = {
  	{
  		.compatible = "motorola,mc146818",
  	},
  	{ },
  };
  MODULE_DEVICE_TABLE(of, of_cmos_match);
  
  static __init void cmos_of_init(struct platform_device *pdev)
  {
  	struct device_node *node = pdev->dev.of_node;
  	struct rtc_time time;
  	int ret;
  	const __be32 *val;
  
  	if (!node)
  		return;
  
  	val = of_get_property(node, "ctrl-reg", NULL);
  	if (val)
  		CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);
  
  	val = of_get_property(node, "freq-reg", NULL);
  	if (val)
  		CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);
  
  	get_rtc_time(&time);
  	ret = rtc_valid_tm(&time);
  	if (ret) {
  		struct rtc_time def_time = {
  			.tm_year = 1,
  			.tm_mday = 1,
  		};
  		set_rtc_time(&def_time);
  	}
  }
  #else
  static inline void cmos_of_init(struct platform_device *pdev) {}
  #endif
  /*----------------------------------------------------------------*/
  
  /* Platform setup should have set up an RTC device, when PNP is
   * unavailable ... this could happen even on (older) PCs.
   */
  
  static int __init cmos_platform_probe(struct platform_device *pdev)
  {
  	struct resource *resource;
  	int irq;
  
  	cmos_of_init(pdev);
  	cmos_wake_setup(&pdev->dev);
  
  	if (RTC_IOMAPPED)
  		resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
  	else
  		resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		irq = -1;
  
  	return cmos_do_probe(&pdev->dev, resource, irq);
  }
  
  static int __exit cmos_platform_remove(struct platform_device *pdev)
  {
  	cmos_do_remove(&pdev->dev);
  	return 0;
  }
  
  static void cmos_platform_shutdown(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
  
  	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(dev))
  		return;
  
  	cmos_do_shutdown(cmos->irq);
  }
  
  /* work with hotplug and coldplug */
  MODULE_ALIAS("platform:rtc_cmos");
  
  static struct platform_driver cmos_platform_driver = {
  	.remove		= __exit_p(cmos_platform_remove),
  	.shutdown	= cmos_platform_shutdown,
  	.driver = {
  		.name		= driver_name,
  #ifdef CONFIG_PM
  		.pm		= &cmos_pm_ops,
  #endif
  		.of_match_table = of_match_ptr(of_cmos_match),
  	}
  };
  
  #ifdef CONFIG_PNP
  static bool pnp_driver_registered;
  #endif
  static bool platform_driver_registered;
  
  static int __init cmos_init(void)
  {
  	int retval = 0;
  
  #ifdef	CONFIG_PNP
  	retval = pnp_register_driver(&cmos_pnp_driver);
  	if (retval == 0)
  		pnp_driver_registered = true;
  #endif
  
  	if (!cmos_rtc.dev) {
  		retval = platform_driver_probe(&cmos_platform_driver,
  					       cmos_platform_probe);
  		if (retval == 0)
  			platform_driver_registered = true;
  	}
  
  	dmi_check_system(rtc_quirks);
  
  	if (retval == 0)
  		return 0;
  
  #ifdef	CONFIG_PNP
  	if (pnp_driver_registered)
  		pnp_unregister_driver(&cmos_pnp_driver);
  #endif
  	return retval;
  }
  module_init(cmos_init);
  
  static void __exit cmos_exit(void)
  {
  #ifdef	CONFIG_PNP
  	if (pnp_driver_registered)
  		pnp_unregister_driver(&cmos_pnp_driver);
  #endif
  	if (platform_driver_registered)
  		platform_driver_unregister(&cmos_platform_driver);
  }
  module_exit(cmos_exit);
  
  
  MODULE_AUTHOR("David Brownell");
  MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
  MODULE_LICENSE("GPL");
  