path: root/drivers/char/rtc.c

/*
 *	Real Time Clock interface for Linux
 *
 *	Copyright (C) 1996 Paul Gortmaker
 *
 *	This driver allows use of the real time clock (built into
 *	nearly all computers) from user space. It exports the /dev/rtc
 *	interface supporting various ioctl() and also the
 *	/proc/driver/rtc pseudo-file for status information.
 *
 *	The ioctls can be used to set the interrupt behaviour and
 *	generation rate from the RTC via IRQ 8. Then the /dev/rtc
 *	interface can be used to make use of these timer interrupts,
 *	be they interval or alarm based.
 *
 *	The /dev/rtc interface will block on reads until an interrupt
 *	has been received. If a RTC interrupt has already happened,
 *	it will output an unsigned long and then block. The output value
 *	contains the interrupt status in the low byte and the number of
 *	interrupts since the last read in the remaining high bytes. The
 *	/dev/rtc interface can also be used with the select(2) call.
 *
 *	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.
 *
 *	Based on other minimal char device drivers, like Alan's
 *	watchdog, Ted's random, etc. etc.
 *
 *	1.07	Paul Gortmaker.
 *	1.08	Miquel van Smoorenburg: disallow certain things on the
 *		DEC Alpha as the CMOS clock is also used for other things.
 *	1.09	Nikita Schmidt: epoch support and some Alpha cleanup.
 *	1.09a	Pete Zaitcev: Sun SPARC
 *	1.09b	Jeff Garzik: Modularize, init cleanup
 *	1.09c	Jeff Garzik: SMP cleanup
 *	1.10	Paul Barton-Davis: add support for async I/O
 *	1.10a	Andrea Arcangeli: Alpha updates
 *	1.10b	Andrew Morton: SMP lock fix
 *	1.10c	Cesar Barros: SMP locking fixes and cleanup
 *	1.10d	Paul Gortmaker: delete paranoia check in rtc_exit
 *	1.10e	Maciej W. Rozycki: Handle DECstation's year weirdness.
 *	1.11	Takashi Iwai: Kernel access functions
 *			      rtc_register/rtc_unregister/rtc_control
 *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
 *	1.12	Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
 *		CONFIG_HPET_EMULATE_RTC
 *	1.12a	Maciej W. Rozycki: Handle memory-mapped chips properly.
 *	1.12ac	Alan Cox: Allow read access to the day of week register
 *	1.12b	David John: Remove calls to the BKL.
 */

#define RTC_VERSION		"1.12b"

/*
 *	Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
 *	interrupts disabled. Due to the index-port/data-port (0x70/0x71)
 *	design of the RTC, we don't want two different things trying to
 *	get to it at once. (e.g. the periodic 11 min sync from time.c vs.
 *	this driver.)
 */

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/wait.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/uaccess.h>

#include <asm/current.h>
#include <asm/system.h>

#ifdef CONFIG_X86
#include <asm/hpet.h>
#endif

#ifdef CONFIG_SPARC32
#include <linux/of.h>
#include <linux/of_device.h>
#include <asm/io.h>

static unsigned long rtc_port;
static int rtc_irq;
#endif

#ifdef	CONFIG_HPET_EMULATE_RTC
#undef	RTC_IRQ