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kernel/drivers/rtc/rtc-cmos.c

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// 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);
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 -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.
*/
/* 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, &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, &p))
return -EIO;
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");
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