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/* SPDX-License-Identifier: GPL-2.0 */
* Generic RTC interface.
* This version contains the part of the user interface to the Real Time Clock
* service. It is used with both the legacy mc146818 and also EFI
* Struct rtc_time and first 12 ioctl by Paul Gortmaker, 1996 - separated out
* from <linux/mc146818rtc.h> to this file for 2.4 kernels.
* Copyright (C) 1999 Hewlett-Packard Co.
* Copyright (C) 1999 Stephane Eranian <>
#ifndef _LINUX_RTC_H_
#define _LINUX_RTC_H_
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/nvmem-provider.h>
#include <uapi/linux/rtc.h>
extern int rtc_month_days(unsigned int month, unsigned int year);
extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year);
extern int rtc_valid_tm(struct rtc_time *tm);
extern time64_t rtc_tm_to_time64(struct rtc_time *tm);
extern void rtc_time64_to_tm(time64_t time, struct rtc_time *tm);
ktime_t rtc_tm_to_ktime(struct rtc_time tm);
struct rtc_time rtc_ktime_to_tm(ktime_t kt);
* rtc_tm_sub - Return the difference in seconds.
static inline time64_t rtc_tm_sub(struct rtc_time *lhs, struct rtc_time *rhs)
return rtc_tm_to_time64(lhs) - rtc_tm_to_time64(rhs);
#include <linux/device.h>
#include <linux/seq_file.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/timerqueue.h>
#include <linux/workqueue.h>
extern struct class *rtc_class;
* For these RTC methods the device parameter is the physical device
* on whatever bus holds the hardware (I2C, Platform, SPI, etc), which
* was passed to rtc_device_register(). Its driver_data normally holds
* device state, including the rtc_device pointer for the RTC.
* Most of these methods are called with rtc_device.ops_lock held,
* through the rtc_*(struct rtc_device *, ...) calls.
* The (current) exceptions are mostly filesystem hooks:
* - the proc() hook for procfs
struct rtc_class_ops {
int (*ioctl)(struct device *, unsigned int, unsigned long);
int (*read_time)(struct device *, struct rtc_time *);
int (*set_time)(struct device *, struct rtc_time *);
int (*read_alarm)(struct device *, struct rtc_wkalrm *);
int (*set_alarm)(struct device *, struct rtc_wkalrm *);
int (*proc)(struct device *, struct seq_file *);
int (*alarm_irq_enable)(struct device *, unsigned int enabled);
int (*read_offset)(struct device *, long *offset);
int (*set_offset)(struct device *, long offset);
int (*param_get)(struct device *, struct rtc_param *param);
int (*param_set)(struct device *, struct rtc_param *param);
struct rtc_device;
struct rtc_timer {
struct timerqueue_node node;
ktime_t period;
void (*func)(struct rtc_device *rtc);
struct rtc_device *rtc;
int enabled;
/* flags */
#define RTC_DEV_BUSY 0
#define RTC_NO_CDEV 1
struct rtc_device {
struct device dev;
struct module *owner;
int id;
const struct rtc_class_ops *ops;
struct mutex ops_lock;
struct cdev char_dev;
unsigned long flags;
unsigned long irq_data;
spinlock_t irq_lock;
wait_queue_head_t irq_queue;
struct fasync_struct *async_queue;
int irq_freq;
int max_user_freq;
struct timerqueue_head timerqueue;
struct rtc_timer aie_timer;
struct rtc_timer uie_rtctimer;
struct hrtimer pie_timer; /* sub second exp, so needs hrtimer */
int pie_enabled;
struct work_struct irqwork;
/* Some hardware can't support UIE mode */
int uie_unsupported;
* This offset specifies the update timing of the RTC.
* tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds
* The offset defines how tsched is computed so that the write to
* the RTC (t2.tv_sec - 1sec) is correct versus the time required
* for the transport of the write and the time which the RTC needs
* to increment seconds the first time after the write (t2).
* For direct accessible RTCs tsched ~= t1 because the write time
* is negligible. For RTCs behind slow busses the transport time is
* significant and has to be taken into account.
* The time between the write (t1) and the first increment after
* the write (t2) is RTC specific. For a MC146818 RTC it's 500ms,
* for many others it's exactly 1 second. Consult the datasheet.
* The value of this offset is also used to calculate the to be
* written value (t2.tv_sec - 1sec) at tsched.
* The default value for this is NSEC_PER_SEC + 10 msec default
* transport time. The offset can be adjusted by drivers so the
* calculation for the to be written value at tsched becomes
* correct:
* newval = tsched + set_offset_nsec - NSEC_PER_SEC
* and (tsched + set_offset_nsec) % NSEC_PER_SEC == 0
unsigned long set_offset_nsec;
unsigned long features[BITS_TO_LONGS(RTC_FEATURE_CNT)];
time64_t range_min;
timeu64_t range_max;
time64_t start_secs;
time64_t offset_secs;
bool set_start_time;
struct work_struct uie_task;
struct timer_list uie_timer;
/* Those fields are protected by rtc->irq_lock */
unsigned int oldsecs;
unsigned int uie_irq_active:1;
unsigned int stop_uie_polling:1;
unsigned int uie_task_active:1;
unsigned int uie_timer_active:1;
#define to_rtc_device(d) container_of(d, struct rtc_device, dev)
#define rtc_lock(d) mutex_lock(&d->ops_lock)
#define rtc_unlock(d) mutex_unlock(&d->ops_lock)
/* useful timestamps */
#define RTC_TIMESTAMP_BEGIN_0000 -62167219200ULL /* 0000-01-01 00:00:00 */
#define RTC_TIMESTAMP_BEGIN_1900 -2208988800LL /* 1900-01-01 00:00:00 */
#define RTC_TIMESTAMP_BEGIN_2000 946684800LL /* 2000-01-01 00:00:00 */
#define RTC_TIMESTAMP_END_2063 2966371199LL /* 2063-12-31 23:59:59 */
#define RTC_TIMESTAMP_END_2079 3471292799LL /* 2079-12-31 23:59:59 */
#define RTC_TIMESTAMP_END_2099 4102444799LL /* 2099-12-31 23:59:59 */
#define RTC_TIMESTAMP_END_2199 7258118399LL /* 2199-12-31 23:59:59 */
#define RTC_TIMESTAMP_END_9999 253402300799LL /* 9999-12-31 23:59:59 */
extern struct rtc_device *devm_rtc_device_register(struct device *dev,
const char *name,
const struct rtc_class_ops *ops,
struct module *owner);
struct rtc_device *devm_rtc_allocate_device(struct device *dev);
int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc);
extern int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm);
extern int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm);
int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm);
extern int rtc_read_alarm(struct rtc_device *rtc,
struct rtc_wkalrm *alrm);
extern int rtc_set_alarm(struct rtc_device *rtc,
struct rtc_wkalrm *alrm);
extern int rtc_initialize_alarm(struct rtc_device *rtc,
struct rtc_wkalrm *alrm);
extern void rtc_update_irq(struct rtc_device *rtc,
unsigned long num, unsigned long events);
extern struct rtc_device *rtc_class_open(const char *name);
extern void rtc_class_close(struct rtc_device *rtc);
extern int rtc_irq_set_state(struct rtc_device *rtc, int enabled);
extern int rtc_irq_set_freq(struct rtc_device *rtc, int freq);
extern int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled);
extern int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled);
extern int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc,
unsigned int enabled);
void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode);
void rtc_aie_update_irq(struct rtc_device *rtc);
void rtc_uie_update_irq(struct rtc_device *rtc);
enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer);
void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
struct rtc_device *rtc);
int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
ktime_t expires, ktime_t period);
void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer);
int rtc_read_offset(struct rtc_device *rtc, long *offset);
int rtc_set_offset(struct rtc_device *rtc, long offset);
void rtc_timer_do_work(struct work_struct *work);
static inline bool is_leap_year(unsigned int year)
return (!(year % 4) && (year % 100)) || !(year % 400);
#define devm_rtc_register_device(device) \
__devm_rtc_register_device(THIS_MODULE, device)
extern int rtc_hctosys_ret;
#define rtc_hctosys_ret -ENODEV
int devm_rtc_nvmem_register(struct rtc_device *rtc,
struct nvmem_config *nvmem_config);
static inline int devm_rtc_nvmem_register(struct rtc_device *rtc,
struct nvmem_config *nvmem_config)
return 0;
int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp);
int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps);
static inline
int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
return 0;
static inline
int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)
return 0;
#endif /* _LINUX_RTC_H_ */