Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1579 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
new file mode 100644
index 000000000..e0a798923
--- /dev/null
+++ b/drivers/rtc/rtc-cmos.c
@@ -0,0 +1,1579 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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)
+ */
+
+/*
+ * 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>
+#ifdef CONFIG_X86
+#include <asm/i8259.h>
+#include <asm/processor.h>
+#include <linux/dmi.h>
+#endif
+
+/* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
+#include <linux/mc146818rtc.h>
+
+#ifdef CONFIG_ACPI
+/*
+ * Use ACPI SCI to replace HPET interrupt for RTC Alarm event
+ *
+ * If cleared, ACPI SCI is only used to wake up the system from suspend
+ *
+ * If set, ACPI SCI is used to handle UIE/AIE and system wakeup
+ */
+
+static bool use_acpi_alarm;
+module_param(use_acpi_alarm, bool, 0444);
+
+static inline int cmos_use_acpi_alarm(void)
+{
+	return use_acpi_alarm;
+}
+#else /* !CONFIG_ACPI */
+
+static inline int cmos_use_acpi_alarm(void)
+{
+	return 0;
+}
+#endif
+
+struct cmos_rtc {
+	struct rtc_device	*rtc;
+	struct device		*dev;
+	int			irq;
+	struct resource		*iomem;
+	time64_t		alarm_expires;
+
+	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;
+
+	struct rtc_wkalrm	saved_wkalrm;
+};
+
+/* 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
+
+/* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */
+static inline int use_hpet_alarm(void)
+{
+	return is_hpet_enabled() && !cmos_use_acpi_alarm();
+}
+
+/*----------------------------------------------------------------*/
+
+#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)
+{
+	int ret;
+
+	/*
+	 * If pm_trace abused the RTC for storage, set the timespec to 0,
+	 * which tells the caller that this RTC value is unusable.
+	 */
+	if (!pm_trace_rtc_valid())
+		return -EIO;
+
+	ret = mc146818_get_time(t, 1000);
+	if (ret < 0) {
+		dev_err_ratelimited(dev, "unable to read current time\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int cmos_set_time(struct device *dev, struct rtc_time *t)
+{
+	/* 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 mc146818_set_time(t);
+}
+
+struct cmos_read_alarm_callback_param {
+	struct cmos_rtc *cmos;
+	struct rtc_time *time;
+	unsigned char	rtc_control;
+};
+
+static void cmos_read_alarm_callback(unsigned char __always_unused seconds,
+				     void *param_in)
+{
+	struct cmos_read_alarm_callback_param *p =
+		(struct cmos_read_alarm_callback_param *)param_in;
+	struct rtc_time *time = p->time;
+
+	time->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
+	time->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
+	time->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
+
+	if (p->cmos->day_alrm) {
+		/* ignore upper bits on readback per ACPI spec */
+		time->tm_mday = CMOS_READ(p->cmos->day_alrm) & 0x3f;
+		if (!time->tm_mday)
+			time->tm_mday = -1;
+
+		if (p->cmos->mon_alrm) {
+			time->tm_mon = CMOS_READ(p->cmos->mon_alrm);
+			if (!time->tm_mon)
+				time->tm_mon = -1;
+		}
+	}
+
+	p->rtc_control = CMOS_READ(RTC_CONTROL);
+}
+
+static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	struct cmos_read_alarm_callback_param p = {
+		.cmos = cmos,
+		.time = &t->time,
+	};
+
+	/* This not only a rtc_op, but also called directly */
+	if (!is_valid_irq(cmos->irq))
+		return -ETIMEDOUT;
+
+	/* Basic alarms only support hour, minute, and seconds fields.
+	 * Some also support day and month, for alarms up to a year in
+	 * the future.
+	 */
+
+	/* Some Intel chipsets disconnect the alarm registers when the clock
+	 * update is in progress - during this time reads return bogus values
+	 * and writes may fail silently. See for example "7th Generation Intel®
+	 * Processor Family I/O for U/Y Platforms [...] Datasheet", section
+	 * 27.7.1
+	 *
+	 * Use the mc146818_avoid_UIP() function to avoid this.
+	 */
+	if (!mc146818_avoid_UIP(cmos_read_alarm_callback, 10, &p))
+		return -EIO;
+
+	if (!(p.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->enabled = !!(p.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 (use_hpet_alarm())
+		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);
+	if (use_hpet_alarm())
+		hpet_set_rtc_irq_bit(mask);
+
+	if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
+		if (cmos->wake_on)
+			cmos->wake_on(cmos->dev);
+	}
+
+	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);
+	if (use_hpet_alarm())
+		hpet_mask_rtc_irq_bit(mask);
+
+	if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
+		if (cmos->wake_off)
+			cmos->wake_off(cmos->dev);
+	}
+
+	cmos_checkintr(cmos, rtc_control);
+}
+
+static int cmos_validate_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct cmos_rtc *cmos = dev_get_drvdata(dev);
+	struct rtc_time now;
+
+	cmos_read_time(dev, &now);
+
+	if (!cmos->day_alrm) {
+		time64_t t_max_date;
+		time64_t t_alrm;
+
+		t_max_date = rtc_tm_to_time64(&now);
+		t_max_date += 24 * 60 * 60 - 1;
+		t_alrm = rtc_tm_to_time64(&t->time);
+		if (t_alrm > t_max_date) {
+			dev_err(dev,
+				"Alarms can be up to one day in the future\n");
+			return -EINVAL;
+		}
+	} else if (!cmos->mon_alrm) {
+		struct rtc_time max_date = now;
+		time64_t t_max_date;
+		time64_t t_alrm;
+		int max_mday;
+
+		if (max_date.tm_mon == 11) {
+			max_date.tm_mon = 0;
+			max_date.tm_year += 1;
+		} else {
+			max_date.tm_mon += 1;
+		}
+		max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
+		if (max_date.tm_mday > max_mday)
+			max_date.tm_mday = max_mday;
+
+		t_max_date = rtc_tm_to_time64(&max_date);
+		t_max_date -= 1;
+		t_alrm = rtc_tm_to_time64(&t->time);
+		if (t_alrm > t_max_date) {
+			dev_err(dev,
+				"Alarms can be up to one month in the future\n");
+			return -EINVAL;
+		}
+	} else {
+		struct rtc_time max_date = now;
+		time64_t t_max_date;
+		time64_t t_alrm;
+		int max_mday;
+
+		max_date.tm_year += 1;
+		max_mday = rtc_month_days(max_date.tm_mon, max_date.tm_year);
+		if (max_date.tm_mday > max_mday)
+			max_date.tm_mday = max_mday;
+
+		t_max_date = rtc_tm_to_time64(&max_date);
+		t_max_date -= 1;
+		t_alrm = rtc_tm_to_time64(&t->time);
+		if (t_alrm > t_max_date) {
+			dev_err(dev,
+				"Alarms can be up to one year in the future\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+struct cmos_set_alarm_callback_param {
+	struct cmos_rtc *cmos;
+	unsigned char mon, mday, hrs, min, sec;
+	struct rtc_wkalrm *t;
+};
+
+/* Note: this function may be executed by mc146818_avoid_UIP() more then
+ *	 once
+ */
+static void cmos_set_alarm_callback(unsigned char __always_unused seconds,
+				    void *param_in)
+{
+	struct cmos_set_alarm_callback_param *p =
+		(struct cmos_set_alarm_callback_param *)param_in;
+
+	/* next rtc irq must not be from previous alarm setting */
+	cmos_irq_disable(p->cmos, RTC_AIE);
+
+	/* update alarm */
+	CMOS_WRITE(p->hrs, RTC_HOURS_ALARM);
+	CMOS_WRITE(p->min, RTC_MINUTES_ALARM);
+	CMOS_WRITE(p->sec, RTC_SECONDS_ALARM);
+
+	/* the system may support an "enhanced" alarm */
+	if (p->cmos->day_alrm) {
+		CMOS_WRITE(p->mday, p->cmos->day_alrm);
+		if (p->cmos->mon_alrm)
+			CMOS_WRITE(p->mon, p->cmos->mon_alrm);
+	}
+
+	if (use_hpet_alarm()) {
+		/*
+		 * FIXME the HPET alarm glue currently ignores day_alrm
+		 * and mon_alrm ...
+		 */
+		hpet_set_alarm_time(p->t->time.tm_hour, p->t->time.tm_min,
+				    p->t->time.tm_sec);
+	}
+
+	if (p->t->enabled)
+		cmos_irq_enable(p->cmos, RTC_AIE);
+}
+
+static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	struct cmos_set_alarm_callback_param p = {
+		.cmos = cmos,
+		.t = t
+	};
+	unsigned char rtc_control;
+	int ret;
+
+	/* This not only a rtc_op, but also called directly */
+	if (!is_valid_irq(cmos->irq))
+		return -EIO;
+
+	ret = cmos_validate_alarm(dev, t);
+	if (ret < 0)
+		return ret;
+
+	p.mon = t->time.tm_mon + 1;
+	p.mday = t->time.tm_mday;
+	p.hrs = t->time.tm_hour;
+	p.min = t->time.tm_min;
+	p.sec = t->time.tm_sec;
+
+	spin_lock_irq(&rtc_lock);
+	rtc_control = CMOS_READ(RTC_CONTROL);
+	spin_unlock_irq(&rtc_lock);
+
+	if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+		/* Writing 0xff means "don't care" or "match all".  */
+		p.mon = (p.mon <= 12) ? bin2bcd(p.mon) : 0xff;
+		p.mday = (p.mday >= 1 && p.mday <= 31) ? bin2bcd(p.mday) : 0xff;
+		p.hrs = (p.hrs < 24) ? bin2bcd(p.hrs) : 0xff;
+		p.min = (p.min < 60) ? bin2bcd(p.min) : 0xff;
+		p.sec = (p.sec < 60) ? bin2bcd(p.sec) : 0xff;
+	}
+
+	/*
+	 * Some Intel chipsets disconnect the alarm registers when the clock
+	 * update is in progress - during this time writes fail silently.
+	 *
+	 * Use mc146818_avoid_UIP() to avoid this.
+	 */
+	if (!mc146818_avoid_UIP(cmos_set_alarm_callback, 10, &p))
+		return -ETIMEDOUT;
+
+	cmos->alarm_expires = rtc_tm_to_time64(&t->time);
+
+	return 0;
+}
+
+static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	unsigned long	flags;
+
+	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 IS_ENABLED(CONFIG_RTC_INTF_PROC)
+
+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",
+		   use_hpet_alarm() ? "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 int cmos_nvram_read(void *priv, unsigned int off, void *val,
+			   size_t count)
+{
+	unsigned char *buf = val;
+	int	retval;
+
+	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 int cmos_nvram_write(void *priv, unsigned int off, void *val,
+			    size_t count)
+{
+	struct cmos_rtc	*cmos = priv;
+	unsigned char	*buf = val;
+	int		retval;
+
+	/* 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 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 (use_hpet_alarm())
+		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);
+		if (use_hpet_alarm())
+			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_ACPI
+
+#include <linux/acpi.h>
+
+static u32 rtc_handler(void *context)
+{
+	struct device *dev = context;
+	struct cmos_rtc *cmos = dev_get_drvdata(dev);
+	unsigned char rtc_control = 0;
+	unsigned char rtc_intr;
+	unsigned long flags;
+
+
+	/*
+	 * Always update rtc irq when ACPI is used as RTC Alarm.
+	 * Or else, ACPI SCI is enabled during suspend/resume only,
+	 * update rtc irq in that case.
+	 */
+	if (cmos_use_acpi_alarm())
+		cmos_interrupt(0, (void *)cmos->rtc);
+	else {
+		/* Fix me: can we use cmos_interrupt() here as well? */
+		spin_lock_irqsave(&rtc_lock, flags);
+		if (cmos_rtc.suspend_ctrl)
+			rtc_control = CMOS_READ(RTC_CONTROL);
+		if (rtc_control & RTC_AIE) {
+			cmos_rtc.suspend_ctrl &= ~RTC_AIE;
+			CMOS_WRITE(rtc_control, RTC_CONTROL);
+			rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+			rtc_update_irq(cmos->rtc, 1, rtc_intr);
+		}
+		spin_unlock_irqrestore(&rtc_lock, flags);
+	}
+
+	pm_wakeup_hard_event(dev);
+	acpi_clear_event(ACPI_EVENT_RTC);
+	acpi_disable_event(ACPI_EVENT_RTC, 0);
+	return ACPI_INTERRUPT_HANDLED;
+}
+
+static void acpi_rtc_event_setup(struct device *dev)
+{
+	if (acpi_disabled)
+		return;
+
+	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 acpi_rtc_event_cleanup(void)
+{
+	if (acpi_disabled)
+		return;
+
+	acpi_remove_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler);
+}
+
+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);
+}
+
+#ifdef CONFIG_X86
+static void use_acpi_alarm_quirks(void)
+{
+	switch (boot_cpu_data.x86_vendor) {
+	case X86_VENDOR_INTEL:
+		if (dmi_get_bios_year() < 2015)
+			return;
+		break;
+	case X86_VENDOR_AMD:
+	case X86_VENDOR_HYGON:
+		if (dmi_get_bios_year() < 2021)
+			return;
+		break;
+	default:
+		return;
+	}
+	if (!is_hpet_enabled())
+		return;
+
+	use_acpi_alarm = true;
+}
+#else
+static inline void use_acpi_alarm_quirks(void) { }
+#endif
+
+static void acpi_cmos_wake_setup(struct device *dev)
+{
+	if (acpi_disabled)
+		return;
+
+	use_acpi_alarm_quirks();
+
+	cmos_rtc.wake_on = rtc_wake_on;
+	cmos_rtc.wake_off = rtc_wake_off;
+
+	/* ACPI tables bug workaround. */
+	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;
+	}
+
+	cmos_rtc.day_alrm = acpi_gbl_FADT.day_alarm;
+	cmos_rtc.mon_alrm = acpi_gbl_FADT.month_alarm;
+	cmos_rtc.century = acpi_gbl_FADT.century;
+
+	if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
+		dev_info(dev, "RTC can wake from S4\n");
+
+	/* RTC always wakes from S1/S2/S3, and often S4/STD */
+	device_init_wakeup(dev, 1);
+}
+
+static void cmos_check_acpi_rtc_status(struct device *dev,
+					      unsigned char *rtc_control)
+{
+	struct cmos_rtc *cmos = dev_get_drvdata(dev);
+	acpi_event_status rtc_status;
+	acpi_status status;
+
+	if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC)
+		return;
+
+	status = acpi_get_event_status(ACPI_EVENT_RTC, &rtc_status);
+	if (ACPI_FAILURE(status)) {
+		dev_err(dev, "Could not get RTC status\n");
+	} else if (rtc_status & ACPI_EVENT_FLAG_SET) {
+		unsigned char mask;
+		*rtc_control &= ~RTC_AIE;
+		CMOS_WRITE(*rtc_control, RTC_CONTROL);
+		mask = CMOS_READ(RTC_INTR_FLAGS);
+		rtc_update_irq(cmos->rtc, 1, mask);
+	}
+}
+
+#else /* !CONFIG_ACPI */
+
+static inline void acpi_rtc_event_setup(struct device *dev)
+{
+}
+
+static inline void acpi_rtc_event_cleanup(void)
+{
+}
+
+static inline void acpi_cmos_wake_setup(struct device *dev)
+{
+}
+
+static inline void cmos_check_acpi_rtc_status(struct device *dev,
+					      unsigned char *rtc_control)
+{
+}
+#endif /* CONFIG_ACPI */
+
+#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;
+	struct nvmem_config nvmem_cfg = {
+		.name = "cmos_nvram",
+		.word_size = 1,
+		.stride = 1,
+		.reg_read = cmos_nvram_read,
+		.reg_write = cmos_nvram_write,
+		.priv = &cmos_rtc,
+	};
+
+	/* 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;
+
+		cmos_rtc.day_alrm = info->rtc_day_alarm;
+		cmos_rtc.mon_alrm = info->rtc_mon_alarm;
+		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;
+		}
+	} else {
+		acpi_cmos_wake_setup(dev);
+	}
+
+	if (cmos_rtc.day_alrm >= 128)
+		cmos_rtc.day_alrm = 0;
+
+	if (cmos_rtc.mon_alrm >= 128)
+		cmos_rtc.mon_alrm = 0;
+
+	if (cmos_rtc.century >= 128)
+		cmos_rtc.century = 0;
+
+	cmos_rtc.dev = dev;
+	dev_set_drvdata(dev, &cmos_rtc);
+
+	cmos_rtc.rtc = devm_rtc_allocate_device(dev);
+	if (IS_ERR(cmos_rtc.rtc)) {
+		retval = PTR_ERR(cmos_rtc.rtc);
+		goto cleanup0;
+	}
+
+	rename_region(ports, dev_name(&cmos_rtc.rtc->dev));
+
+	if (!mc146818_does_rtc_work()) {
+		dev_warn(dev, "broken or not accessible\n");
+		retval = -ENXIO;
+		goto cleanup1;
+	}
+
+	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;
+		if (use_hpet_alarm())
+			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);
+
+	if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
+		dev_warn(dev, "only 24-hr supported\n");
+		retval = -ENXIO;
+		goto cleanup1;
+	}
+
+	if (use_hpet_alarm())
+		hpet_rtc_timer_init();
+
+	if (is_valid_irq(rtc_irq)) {
+		irq_handler_t rtc_cmos_int_handler;
+
+		if (use_hpet_alarm()) {
+			rtc_cmos_int_handler = hpet_rtc_interrupt;
+			retval = hpet_register_irq_handler(cmos_interrupt);
+			if (retval) {
+				hpet_mask_rtc_irq_bit(RTC_IRQMASK);
+				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;
+		}
+	} else {
+		clear_bit(RTC_FEATURE_ALARM, cmos_rtc.rtc->features);
+	}
+
+	cmos_rtc.rtc->ops = &cmos_rtc_ops;
+
+	retval = devm_rtc_register_device(cmos_rtc.rtc);
+	if (retval)
+		goto cleanup2;
+
+	/* Set the sync offset for the periodic 11min update correct */
+	cmos_rtc.rtc->set_offset_nsec = NSEC_PER_SEC / 2;
+
+	/* export at least the first block of NVRAM */
+	nvmem_cfg.size = address_space - NVRAM_OFFSET;
+	devm_rtc_nvmem_register(cmos_rtc.rtc, &nvmem_cfg);
+
+	/*
+	 * Everything has gone well so far, so by default register a handler for
+	 * the ACPI RTC fixed event.
+	 */
+	if (!info)
+		acpi_rtc_event_setup(dev);
+
+	dev_info(dev, "%s%s, %d 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" : "",
+		 nvmem_cfg.size,
+		 use_hpet_alarm() ? ", hpet irqs" : "");
+
+	return 0;
+
+cleanup2:
+	if (is_valid_irq(rtc_irq))
+		free_irq(rtc_irq, cmos_rtc.rtc);
+cleanup1:
+	cmos_rtc.dev = NULL;
+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 cmos_do_remove(struct device *dev)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	struct resource *ports;
+
+	cmos_do_shutdown(cmos->irq);
+
+	if (is_valid_irq(cmos->irq)) {
+		free_irq(cmos->irq, cmos->rtc);
+		if (use_hpet_alarm())
+			hpet_unregister_irq_handler(cmos_interrupt);
+	}
+
+	if (!dev_get_platdata(dev))
+		acpi_rtc_event_cleanup();
+
+	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;
+}
+
+static int cmos_aie_poweroff(struct device *dev)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	struct rtc_time now;
+	time64_t t_now;
+	int retval = 0;
+	unsigned char rtc_control;
+
+	if (!cmos->alarm_expires)
+		return -EINVAL;
+
+	spin_lock_irq(&rtc_lock);
+	rtc_control = CMOS_READ(RTC_CONTROL);
+	spin_unlock_irq(&rtc_lock);
+
+	/* We only care about the situation where AIE is disabled. */
+	if (rtc_control & RTC_AIE)
+		return -EBUSY;
+
+	cmos_read_time(dev, &now);
+	t_now = rtc_tm_to_time64(&now);
+
+	/*
+	 * When enabling "RTC wake-up" in BIOS setup, the machine reboots
+	 * automatically right after shutdown on some buggy boxes.
+	 * This automatic rebooting issue won't happen when the alarm
+	 * time is larger than now+1 seconds.
+	 *
+	 * If the alarm time is equal to now+1 seconds, the issue can be
+	 * prevented by cancelling the alarm.
+	 */
+	if (cmos->alarm_expires == t_now + 1) {
+		struct rtc_wkalrm alarm;
+
+		/* Cancel the AIE timer by configuring the past time. */
+		rtc_time64_to_tm(t_now - 1, &alarm.time);
+		alarm.enabled = 0;
+		retval = cmos_set_alarm(dev, &alarm);
+	} else if (cmos->alarm_expires > t_now + 1) {
+		retval = -EBUSY;
+	}
+
+	return retval;
+}
+
+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);
+		if (use_hpet_alarm())
+			hpet_mask_rtc_irq_bit(mask);
+		cmos_checkintr(cmos, tmp);
+	}
+	spin_unlock_irq(&rtc_lock);
+
+	if ((tmp & RTC_AIE) && !cmos_use_acpi_alarm()) {
+		cmos->enabled_wake = 1;
+		if (cmos->wake_on)
+			cmos->wake_on(dev);
+		else
+			enable_irq_wake(cmos->irq);
+	}
+
+	memset(&cmos->saved_wkalrm, 0, sizeof(struct rtc_wkalrm));
+	cmos_read_alarm(dev, &cmos->saved_wkalrm);
+
+	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)
+{
+	if (!IS_ENABLED(CONFIG_PM))
+		return -ENOSYS;
+
+	return cmos_suspend(dev);
+}
+
+static void cmos_check_wkalrm(struct device *dev)
+{
+	struct cmos_rtc *cmos = dev_get_drvdata(dev);
+	struct rtc_wkalrm current_alarm;
+	time64_t t_now;
+	time64_t t_current_expires;
+	time64_t t_saved_expires;
+	struct rtc_time now;
+
+	/* Check if we have RTC Alarm armed */
+	if (!(cmos->suspend_ctrl & RTC_AIE))
+		return;
+
+	cmos_read_time(dev, &now);
+	t_now = rtc_tm_to_time64(&now);
+
+	/*
+	 * ACPI RTC wake event is cleared after resume from STR,
+	 * ACK the rtc irq here
+	 */
+	if (t_now >= cmos->alarm_expires && cmos_use_acpi_alarm()) {
+		local_irq_disable();
+		cmos_interrupt(0, (void *)cmos->rtc);
+		local_irq_enable();
+		return;
+	}
+
+	memset(&current_alarm, 0, sizeof(struct rtc_wkalrm));
+	cmos_read_alarm(dev, &current_alarm);
+	t_current_expires = rtc_tm_to_time64(&current_alarm.time);
+	t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);
+	if (t_current_expires != t_saved_expires ||
+	    cmos->saved_wkalrm.enabled != current_alarm.enabled) {
+		cmos_set_alarm(dev, &cmos->saved_wkalrm);
+	}
+}
+
+static int __maybe_unused cmos_resume(struct device *dev)
+{
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+	unsigned char tmp;
+
+	if (cmos->enabled_wake && !cmos_use_acpi_alarm()) {
+		if (cmos->wake_off)
+			cmos->wake_off(dev);
+		else
+			disable_irq_wake(cmos->irq);
+		cmos->enabled_wake = 0;
+	}
+
+	/* The BIOS might have changed the alarm, restore it */
+	cmos_check_wkalrm(dev);
+
+	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) && use_hpet_alarm())
+			hpet_rtc_timer_init();
+
+		do {
+			CMOS_WRITE(tmp, RTC_CONTROL);
+			if (use_hpet_alarm())
+				hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);
+
+			mask = CMOS_READ(RTC_INTR_FLAGS);
+			mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
+			if (!use_hpet_alarm() || !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);
+
+		if (tmp & RTC_AIE)
+			cmos_check_acpi_rtc_status(dev, &tmp);
+	}
+	spin_unlock_irq(&rtc_lock);
+
+	dev_dbg(dev, "resume, ctrl %02x\n", tmp);
+
+	return 0;
+}
+
+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_PNP
+
+#include <linux/pnp.h>
+
+static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
+{
+	int irq;
+
+	if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) {
+		irq = 0;
+#ifdef CONFIG_X86
+		/* Some machines contain a PNP entry for the RTC, but
+		 * don't define the IRQ. It should always be safe to
+		 * hardcode it on systems with a legacy PIC.
+		 */
+		if (nr_legacy_irqs())
+			irq = RTC_IRQ;
+#endif
+	} else {
+		irq = pnp_irq(pnp, 0);
+	}
+
+	return cmos_do_probe(&pnp->dev, pnp_get_resource(pnp, IORESOURCE_IO, 0), irq);
+}
+
+static void 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) {
+		int retval = cmos_poweroff(dev);
+
+		if (cmos_aie_poweroff(dev) < 0 && !retval)
+			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		= driver_name,
+	.id_table	= rtc_ids,
+	.probe		= cmos_pnp_probe,
+	.remove		= 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;
+	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);
+}
+#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);
+
+	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 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) {
+		int retval = cmos_poweroff(dev);
+
+		if (cmos_aie_poweroff(dev) < 0 && !retval)
+			return;
+	}
+
+	cmos_do_shutdown(cmos->irq);
+}
+
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:rtc_cmos");
+
+static struct platform_driver cmos_platform_driver = {
+	.remove		= cmos_platform_remove,
+	.shutdown	= cmos_platform_shutdown,
+	.driver = {
+		.name		= driver_name,
+		.pm		= &cmos_pm_ops,
+		.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;
+	}
+
+	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");