rtc-cmos.c

linux 内核源代码

/*
 * 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.
 */
#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/mod_devicetable.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;
}

/*----------------------------------------------------------------*/

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);

	/* REVISIT this assumes PC style usage:  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 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;
	unsigned char	rtc_control, rtc_intr;

	if (!is_valid_irq(cmos->irq))
		return -EIO;

	/* REVISIT this assumes PC style usage:  always BCD */

	/* Writing 0xff means "don't care" or "match all".  */

	mon = t->time.tm_mon;
	mon = (mon < 12) ? BIN2BCD(mon) : 0xff;
	mon++;

	mday = t->time.tm_mday;
	mday = (mday >= 1 && mday <= 31) ? BIN2BCD(mday) : 0xff;

	hrs = t->time.tm_hour;
	hrs = (hrs < 24) ? BIN2BCD(hrs) : 0xff;

	min = t->time.tm_min;
	min = (min < 60) ? BIN2BCD(min) : 0xff;

	sec = t->time.tm_sec;
	sec = (sec < 60) ? BIN2BCD(sec) : 0xff;

	spin_lock_irq(&rtc_lock);

	/* next rtc irq must not be from previous alarm setting */
	rtc_control = CMOS_READ(RTC_CONTROL);
	rtc_control &= ~RTC_AIE;
	CMOS_WRITE(rtc_control, RTC_CONTROL);
	rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
	rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
	if (is_intr(rtc_intr))
		rtc_update_irq(cmos->rtc, 1, rtc_intr);

	/* 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);
	}

	if (t->enabled) {
		rtc_control |= RTC_AIE;
		CMOS_WRITE(rtc_control, RTC_CONTROL);
		rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
		rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
		if (is_intr(rtc_intr))
			rtc_update_irq(cmos->rtc, 1, rtc_intr);
	}

	spin_unlock_irq(&rtc_lock);

	return 0;
}

static int cmos_irq_set_freq(struct device *dev, int freq)
{
	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
	int		f;
	unsigned long	flags;

	if (!is_valid_irq(cmos->irq))
		return -ENXIO;

	/* 0 = no irqs; 1 = 2^15 Hz ... 15 = 2^0 Hz */
	f = ffs(freq);
	if (f-- > 16)
		return -EINVAL;
	f = 16 - f;

	spin_lock_irqsave(&rtc_lock, flags);
	CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);
	spin_unlock_irqrestore(&rtc_lock, flags);

	return 0;
}

static int cmos_irq_set_state(struct device *dev, int enabled)
{
	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
	unsigned char	rtc_control, rtc_intr;
	unsigned long	flags;

	if (!is_valid_irq(cmos->irq))
		return -ENXIO;

	spin_lock_irqsave(&rtc_lock, flags);
	rtc_control = CMOS_READ(RTC_CONTROL);

	if (enabled)
		rtc_control |= RTC_PIE;
	else
		rtc_control &= ~RTC_PIE;

	CMOS_WRITE(rtc_control, RTC_CONTROL);

	rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
	rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
	if (is_intr(rtc_intr))
		rtc_update_irq(cmos->rtc, 1, rtc_intr);

	spin_unlock_irqrestore(&rtc_lock, flags);
	return 0;
}

#if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)

static int
cmos_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
	unsigned char	rtc_control, rtc_intr;
	unsigned long	flags;

	switch (cmd) {
	case RTC_AIE_OFF:
	case RTC_AIE_ON:
	case RTC_UIE_OFF:
	case RTC_UIE_ON:
	case RTC_PIE_OFF:
	case RTC_PIE_ON:
		if (!is_valid_irq(cmos->irq))
			return -EINVAL;
		break;
	default:
		return -ENOIOCTLCMD;
	}

	spin_lock_irqsave(&rtc_lock, flags);
	rtc_control = CMOS_READ(RTC_CONTROL);
	switch (cmd) {
	case RTC_AIE_OFF:	/* alarm off */
		rtc_control &= ~RTC_AIE;
		break;
	case RTC_AIE_ON:	/* alarm on */
		rtc_control |= RTC_AIE;
		break;
	case RTC_UIE_OFF:	/* update off */
		rtc_control &= ~RTC_UIE;
		break;
	case RTC_UIE_ON:	/* update on */
		rtc_control |= RTC_UIE;
		break;
	case RTC_PIE_OFF:	/* periodic off */
		rtc_control &= ~RTC_PIE;
		break;
	case RTC_PIE_ON:	/* periodic on */
		rtc_control |= RTC_PIE;
		break;
	}
	CMOS_WRITE(rtc_control, RTC_CONTROL);
	rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
	rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
	if (is_intr(rtc_intr))
		rtc_update_irq(cmos->rtc, 1, rtc_intr);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return 0;
}

#else
#define	cmos_rtc_ioctl	NULL
#endif

#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.
	 */
	return seq_printf(seq,
			"periodic_IRQ\t: %s\n"
			"update_IRQ\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",
			// (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");
}

#else
#define	cmos_procfs	NULL
#endif

static const struct rtc_class_ops cmos_rtc_ops = {
	.ioctl		= cmos_rtc_ioctl,
	.read_time	= cmos_read_time,
	.set_time	= cmos_set_time,
	.read_alarm	= cmos_read_alarm,
	.set_alarm	= cmos_set_alarm,
	.proc		= cmos_procfs,
	.irq_set_freq	= cmos_irq_set_freq,
	.irq_set_state	= cmos_irq_set_state,
};

/*----------------------------------------------------------------*/

static struct cmos_rtc	cmos_rtc;

static irqreturn_t cmos_interrupt(int irq, void *p)
{
	u8		irqstat;