Re: [PATCH 2/2] rtc/alpha: remove legacy rtc driver

[Alexandre Belloni]

On 23/10/2019 17:01:59+0200, Arnd Bergmann wrote:
> The old drivers/char/rtc.c driver was originally the implementation
> for x86 PCs but got subsequently replaced by the rtc class driver
> on all architectures except alpha.
> 
> Move alpha over to the portable driver and remove the old one
> for good.
> 
> The CONFIG_JS_RTC option was only ever used on SPARC32 but
> has not been available for many years, this was used to build
> the same rtc driver with a different module name.
> 
> Cc: Richard Henderson <rth@xxxxxxxxxxx>
> Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
> Cc: Matt Turner <mattst88@xxxxxxxxx>
> Cc: linux-alpha@xxxxxxxxxxxxxxx
> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>

> ---
> This was last discussed in early 2018 in
> https://lore.kernel.org/lkml/CAK8P3a0QZNY+K+V1HG056xCerz=_L2jh5UfZ+2LWkDqkw5Zznw@xxxxxxxxxxxxxx/
> 
> Nobody ever replied there, so let's try this instead.
> If there is any reason to keep the driver after all,
> please let us know.
> ---
>  arch/alpha/configs/defconfig |    3 +-
>  drivers/char/Kconfig         |   56 --
>  drivers/char/Makefile        |    4 -
>  drivers/char/rtc.c           | 1311 ----------------------------------
>  4 files changed, 2 insertions(+), 1372 deletions(-)
>  delete mode 100644 drivers/char/rtc.c
> 
> diff --git a/arch/alpha/configs/defconfig b/arch/alpha/configs/defconfig
> index f4ec420d7f2d..e10c1be3c0d1 100644
> --- a/arch/alpha/configs/defconfig
> +++ b/arch/alpha/configs/defconfig
> @@ -53,7 +53,8 @@ CONFIG_NET_PCI=y
>  CONFIG_YELLOWFIN=y
>  CONFIG_SERIAL_8250=y
>  CONFIG_SERIAL_8250_CONSOLE=y
> -CONFIG_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_CMOS=y
>  CONFIG_EXT2_FS=y
>  CONFIG_REISERFS_FS=m
>  CONFIG_ISO9660_FS=y
> diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
> index dabbf3f519c6..c2ac4f257c82 100644
> --- a/drivers/char/Kconfig
> +++ b/drivers/char/Kconfig
> @@ -243,62 +243,6 @@ config NVRAM
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called nvram.
>  
> -#
> -# These legacy RTC drivers just cause too many conflicts with the generic
> -# RTC framework ... let's not even try to coexist any more.
> -#
> -if RTC_LIB=n
> -
> -config RTC
> -	tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)"
> -	depends on ALPHA
> -	---help---
> -	  If you say Y here and create a character special file /dev/rtc with
> -	  major number 10 and minor number 135 using mknod ("man mknod"), you
> -	  will get access to the real time clock (or hardware clock) built
> -	  into your computer.
> -
> -	  Every PC has such a clock built in. It can be used to generate
> -	  signals from as low as 1Hz up to 8192Hz, and can also be used
> -	  as a 24 hour alarm. It reports status information via the file
> -	  /proc/driver/rtc and its behaviour is set by various ioctls on
> -	  /dev/rtc.
> -
> -	  If you run Linux on a multiprocessor machine and said Y to
> -	  "Symmetric Multi Processing" above, you should say Y here to read
> -	  and set the RTC in an SMP compatible fashion.
> -
> -	  If you think you have a use for such a device (such as periodic data
> -	  sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst>
> -	  for details.
> -
> -	  To compile this driver as a module, choose M here: the
> -	  module will be called rtc.
> -
> -config JS_RTC
> -	tristate "Enhanced Real Time Clock Support"
> -	depends on SPARC32 && PCI
> -	---help---
> -	  If you say Y here and create a character special file /dev/rtc with
> -	  major number 10 and minor number 135 using mknod ("man mknod"), you
> -	  will get access to the real time clock (or hardware clock) built
> -	  into your computer.
> -
> -	  Every PC has such a clock built in. It can be used to generate
> -	  signals from as low as 1Hz up to 8192Hz, and can also be used
> -	  as a 24 hour alarm. It reports status information via the file
> -	  /proc/driver/rtc and its behaviour is set by various ioctls on
> -	  /dev/rtc.
> -
> -	  If you think you have a use for such a device (such as periodic data
> -	  sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst>
> -	  for details.
> -
> -	  To compile this driver as a module, choose M here: the
> -	  module will be called js-rtc.
> -
> -endif # RTC_LIB
> -
>  config DTLK
>  	tristate "Double Talk PC internal speech card support"
>  	depends on ISA
> diff --git a/drivers/char/Makefile b/drivers/char/Makefile
> index abe3138b1f5a..ffce287ef415 100644
> --- a/drivers/char/Makefile
> +++ b/drivers/char/Makefile
> @@ -20,7 +20,6 @@ obj-$(CONFIG_APM_EMULATION)	+= apm-emulation.o
>  obj-$(CONFIG_DTLK)		+= dtlk.o
>  obj-$(CONFIG_APPLICOM)		+= applicom.o
>  obj-$(CONFIG_SONYPI)		+= sonypi.o
> -obj-$(CONFIG_RTC)		+= rtc.o
>  obj-$(CONFIG_HPET)		+= hpet.o
>  obj-$(CONFIG_XILINX_HWICAP)	+= xilinx_hwicap/
>  obj-$(CONFIG_NVRAM)		+= nvram.o
> @@ -45,9 +44,6 @@ obj-$(CONFIG_TCG_TPM)		+= tpm/
>  
>  obj-$(CONFIG_PS3_FLASH)		+= ps3flash.o
>  
> -obj-$(CONFIG_JS_RTC)		+= js-rtc.o
> -js-rtc-y = rtc.o
> -
>  obj-$(CONFIG_XILLYBUS)		+= xillybus/
>  obj-$(CONFIG_POWERNV_OP_PANEL)	+= powernv-op-panel.o
>  obj-$(CONFIG_ADI)		+= adi.o
> diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
> deleted file mode 100644
> index 3b91184b77ae..000000000000
> --- a/drivers/char/rtc.c
> +++ /dev/null
> @@ -1,1311 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-or-later
> -/*
> - *	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.
> - *
> - *	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
> - *      kernel/time/ntp.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/sched/signal.h>
> -#include <linux/sysctl.h>
> -#include <linux/wait.h>
> -#include <linux/bcd.h>
> -#include <linux/delay.h>
> -#include <linux/uaccess.h>
> -#include <linux/ratelimit.h>
> -
> -#include <asm/current.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
> -#endif
> -
> -#ifdef RTC_IRQ
> -static int rtc_has_irq = 1;
> -#endif
> -
> -#ifndef CONFIG_HPET_EMULATE_RTC
> -#define is_hpet_enabled()			0
> -#define hpet_set_alarm_time(hrs, min, sec)	0
> -#define hpet_set_periodic_freq(arg)		0
> -#define hpet_mask_rtc_irq_bit(arg)		0
> -#define hpet_set_rtc_irq_bit(arg)		0
> -#define hpet_rtc_timer_init()			do { } while (0)
> -#define hpet_rtc_dropped_irq()			0
> -#define hpet_register_irq_handler(h)		({ 0; })
> -#define hpet_unregister_irq_handler(h)		({ 0; })
> -#ifdef RTC_IRQ
> -static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
> -{
> -	return 0;
> -}
> -#endif
> -#endif
> -
> -/*
> - *	We sponge a minor off of the misc major. No need slurping
> - *	up another valuable major dev number for this. If you add
> - *	an ioctl, make sure you don't conflict with SPARC's RTC
> - *	ioctls.
> - */
> -
> -static struct fasync_struct *rtc_async_queue;
> -
> -static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
> -
> -#ifdef RTC_IRQ
> -static void rtc_dropped_irq(struct timer_list *unused);
> -
> -static DEFINE_TIMER(rtc_irq_timer, rtc_dropped_irq);
> -#endif
> -
> -static ssize_t rtc_read(struct file *file, char __user *buf,
> -			size_t count, loff_t *ppos);
> -
> -static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
> -static void rtc_get_rtc_time(struct rtc_time *rtc_tm);
> -
> -#ifdef RTC_IRQ
> -static __poll_t rtc_poll(struct file *file, poll_table *wait);
> -#endif
> -
> -static void get_rtc_alm_time(struct rtc_time *alm_tm);
> -#ifdef RTC_IRQ
> -static void set_rtc_irq_bit_locked(unsigned char bit);
> -static void mask_rtc_irq_bit_locked(unsigned char bit);
> -
> -static inline void set_rtc_irq_bit(unsigned char bit)
> -{
> -	spin_lock_irq(&rtc_lock);
> -	set_rtc_irq_bit_locked(bit);
> -	spin_unlock_irq(&rtc_lock);
> -}
> -
> -static void mask_rtc_irq_bit(unsigned char bit)
> -{
> -	spin_lock_irq(&rtc_lock);
> -	mask_rtc_irq_bit_locked(bit);
> -	spin_unlock_irq(&rtc_lock);
> -}
> -#endif
> -
> -#ifdef CONFIG_PROC_FS
> -static int rtc_proc_show(struct seq_file *seq, void *v);
> -#endif
> -
> -/*
> - *	Bits in rtc_status. (6 bits of room for future expansion)
> - */
> -
> -#define RTC_IS_OPEN		0x01	/* means /dev/rtc is in use	*/
> -#define RTC_TIMER_ON		0x02	/* missed irq timer active	*/
> -
> -/*
> - * rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
> - * protected by the spin lock rtc_lock. However, ioctl can still disable the
> - * timer in rtc_status and then with del_timer after the interrupt has read
> - * rtc_status but before mod_timer is called, which would then reenable the
> - * timer (but you would need to have an awful timing before you'd trip on it)
> - */
> -static unsigned long rtc_status;	/* bitmapped status byte.	*/
> -static unsigned long rtc_freq;		/* Current periodic IRQ rate	*/
> -static unsigned long rtc_irq_data;	/* our output to the world	*/
> -static unsigned long rtc_max_user_freq = 64; /* > this, need CAP_SYS_RESOURCE */
> -
> -/*
> - *	If this driver ever becomes modularised, it will be really nice
> - *	to make the epoch retain its value across module reload...
> - */
> -
> -static unsigned long epoch = 1900;	/* year corresponding to 0x00	*/
> -
> -static const unsigned char days_in_mo[] =
> -{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
> -
> -/*
> - * Returns true if a clock update is in progress
> - */
> -static inline unsigned char rtc_is_updating(void)
> -{
> -	unsigned long flags;
> -	unsigned char uip;
> -
> -	spin_lock_irqsave(&rtc_lock, flags);
> -	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
> -	spin_unlock_irqrestore(&rtc_lock, flags);
> -	return uip;
> -}
> -
> -#ifdef RTC_IRQ
> -/*
> - *	A very tiny interrupt handler. It runs with interrupts disabled,
> - *	but there is possibility of conflicting with the set_rtc_mmss()
> - *	call (the rtc irq and the timer irq can easily run at the same
> - *	time in two different CPUs). So we need to serialize
> - *	accesses to the chip with the rtc_lock spinlock that each
> - *	architecture should implement in the timer code.
> - *	(See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
> - */
> -
> -static irqreturn_t rtc_interrupt(int irq, void *dev_id)
> -{
> -	/*
> -	 *	Can be an alarm interrupt, update complete interrupt,
> -	 *	or a periodic interrupt. We store the status in the
> -	 *	low byte and the number of interrupts received since
> -	 *	the last read in the remainder of rtc_irq_data.
> -	 */
> -
> -	spin_lock(&rtc_lock);
> -	rtc_irq_data += 0x100;
> -	rtc_irq_data &= ~0xff;
> -	if (is_hpet_enabled()) {
> -		/*
> -		 * In this case it is HPET RTC interrupt handler
> -		 * calling us, with the interrupt information
> -		 * passed as arg1, instead of irq.
> -		 */
> -		rtc_irq_data |= (unsigned long)irq & 0xF0;
> -	} else {
> -		rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
> -	}
> -
> -	if (rtc_status & RTC_TIMER_ON)
> -		mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
> -
> -	spin_unlock(&rtc_lock);
> -
> -	wake_up_interruptible(&rtc_wait);
> -
> -	kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
> -
> -	return IRQ_HANDLED;
> -}
> -#endif
> -
> -/*
> - * sysctl-tuning infrastructure.
> - */
> -static struct ctl_table rtc_table[] = {
> -	{
> -		.procname	= "max-user-freq",
> -		.data		= &rtc_max_user_freq,
> -		.maxlen		= sizeof(int),
> -		.mode		= 0644,
> -		.proc_handler	= proc_dointvec,
> -	},
> -	{ }
> -};
> -
> -static struct ctl_table rtc_root[] = {
> -	{
> -		.procname	= "rtc",
> -		.mode		= 0555,
> -		.child		= rtc_table,
> -	},
> -	{ }
> -};
> -
> -static struct ctl_table dev_root[] = {
> -	{
> -		.procname	= "dev",
> -		.mode		= 0555,
> -		.child		= rtc_root,
> -	},
> -	{ }
> -};
> -
> -static struct ctl_table_header *sysctl_header;
> -
> -static int __init init_sysctl(void)
> -{
> -    sysctl_header = register_sysctl_table(dev_root);
> -    return 0;
> -}
> -
> -static void __exit cleanup_sysctl(void)
> -{
> -    unregister_sysctl_table(sysctl_header);
> -}
> -
> -/*
> - *	Now all the various file operations that we export.
> - */
> -
> -static ssize_t rtc_read(struct file *file, char __user *buf,
> -			size_t count, loff_t *ppos)
> -{
> -#ifndef RTC_IRQ
> -	return -EIO;
> -#else
> -	DECLARE_WAITQUEUE(wait, current);
> -	unsigned long data;
> -	ssize_t retval;
> -
> -	if (rtc_has_irq == 0)
> -		return -EIO;
> -
> -	/*
> -	 * Historically this function used to assume that sizeof(unsigned long)
> -	 * is the same in userspace and kernelspace.  This lead to problems
> -	 * for configurations with multiple ABIs such a the MIPS o32 and 64
> -	 * ABIs supported on the same kernel.  So now we support read of both
> -	 * 4 and 8 bytes and assume that's the sizeof(unsigned long) in the
> -	 * userspace ABI.
> -	 */
> -	if (count != sizeof(unsigned int) && count !=  sizeof(unsigned long))
> -		return -EINVAL;
> -
> -	add_wait_queue(&rtc_wait, &wait);
> -
> -	do {
> -		/* First make it right. Then make it fast. Putting this whole
> -		 * block within the parentheses of a while would be too
> -		 * confusing. And no, xchg() is not the answer. */
> -
> -		__set_current_state(TASK_INTERRUPTIBLE);
> -
> -		spin_lock_irq(&rtc_lock);
> -		data = rtc_irq_data;
> -		rtc_irq_data = 0;
> -		spin_unlock_irq(&rtc_lock);
> -
> -		if (data != 0)
> -			break;
> -
> -		if (file->f_flags & O_NONBLOCK) {
> -			retval = -EAGAIN;
> -			goto out;
> -		}
> -		if (signal_pending(current)) {
> -			retval = -ERESTARTSYS;
> -			goto out;
> -		}
> -		schedule();
> -	} while (1);
> -
> -	if (count == sizeof(unsigned int)) {
> -		retval = put_user(data,
> -				  (unsigned int __user *)buf) ?: sizeof(int);
> -	} else {
> -		retval = put_user(data,
> -				  (unsigned long __user *)buf) ?: sizeof(long);
> -	}
> -	if (!retval)
> -		retval = count;
> - out:
> -	__set_current_state(TASK_RUNNING);
> -	remove_wait_queue(&rtc_wait, &wait);
> -
> -	return retval;
> -#endif
> -}
> -
> -static int rtc_do_ioctl(unsigned int cmd, unsigned long arg, int kernel)
> -{
> -	struct rtc_time wtime;
> -
> -#ifdef RTC_IRQ
> -	if (rtc_has_irq == 0) {
> -		switch (cmd) {
> -		case RTC_AIE_OFF:
> -		case RTC_AIE_ON:
> -		case RTC_PIE_OFF:
> -		case RTC_PIE_ON:
> -		case RTC_UIE_OFF:
> -		case RTC_UIE_ON:
> -		case RTC_IRQP_READ:
> -		case RTC_IRQP_SET:
> -			return -EINVAL;
> -		}
> -	}
> -#endif
> -
> -	switch (cmd) {
> -#ifdef RTC_IRQ
> -	case RTC_AIE_OFF:	/* Mask alarm int. enab. bit	*/
> -	{
> -		mask_rtc_irq_bit(RTC_AIE);
> -		return 0;
> -	}
> -	case RTC_AIE_ON:	/* Allow alarm interrupts.	*/
> -	{
> -		set_rtc_irq_bit(RTC_AIE);
> -		return 0;
> -	}
> -	case RTC_PIE_OFF:	/* Mask periodic int. enab. bit	*/
> -	{
> -		/* can be called from isr via rtc_control() */
> -		unsigned long flags;
> -
> -		spin_lock_irqsave(&rtc_lock, flags);
> -		mask_rtc_irq_bit_locked(RTC_PIE);
> -		if (rtc_status & RTC_TIMER_ON) {
> -			rtc_status &= ~RTC_TIMER_ON;
> -			del_timer(&rtc_irq_timer);
> -		}
> -		spin_unlock_irqrestore(&rtc_lock, flags);
> -
> -		return 0;
> -	}
> -	case RTC_PIE_ON:	/* Allow periodic ints		*/
> -	{
> -		/* can be called from isr via rtc_control() */
> -		unsigned long flags;
> -
> -		/*
> -		 * We don't really want Joe User enabling more
> -		 * than 64Hz of interrupts on a multi-user machine.
> -		 */
> -		if (!kernel && (rtc_freq > rtc_max_user_freq) &&
> -						(!capable(CAP_SYS_RESOURCE)))
> -			return -EACCES;
> -
> -		spin_lock_irqsave(&rtc_lock, flags);
> -		if (!(rtc_status & RTC_TIMER_ON)) {
> -			mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq +
> -					2*HZ/100);
> -			rtc_status |= RTC_TIMER_ON;
> -		}
> -		set_rtc_irq_bit_locked(RTC_PIE);
> -		spin_unlock_irqrestore(&rtc_lock, flags);
> -
> -		return 0;
> -	}
> -	case RTC_UIE_OFF:	/* Mask ints from RTC updates.	*/
> -	{
> -		mask_rtc_irq_bit(RTC_UIE);
> -		return 0;
> -	}
> -	case RTC_UIE_ON:	/* Allow ints for RTC updates.	*/
> -	{
> -		set_rtc_irq_bit(RTC_UIE);
> -		return 0;
> -	}
> -#endif
> -	case RTC_ALM_READ:	/* Read the present alarm time */
> -	{
> -		/*
> -		 * This returns a struct rtc_time. Reading >= 0xc0
> -		 * means "don't care" or "match all". Only the tm_hour,
> -		 * tm_min, and tm_sec values are filled in.
> -		 */
> -		memset(&wtime, 0, sizeof(struct rtc_time));
> -		get_rtc_alm_time(&wtime);
> -		break;
> -	}
> -	case RTC_ALM_SET:	/* Store a time into the alarm */
> -	{
> -		/*
> -		 * This expects a struct rtc_time. Writing 0xff means
> -		 * "don't care" or "match all". Only the tm_hour,
> -		 * tm_min and tm_sec are used.
> -		 */
> -		unsigned char hrs, min, sec;
> -		struct rtc_time alm_tm;
> -
> -		if (copy_from_user(&alm_tm, (struct rtc_time __user *)arg,
> -				   sizeof(struct rtc_time)))
> -			return -EFAULT;
> -
> -		hrs = alm_tm.tm_hour;
> -		min = alm_tm.tm_min;
> -		sec = alm_tm.tm_sec;
> -
> -		spin_lock_irq(&rtc_lock);
> -		if (hpet_set_alarm_time(hrs, min, sec)) {
> -			/*
> -			 * Fallthru and set alarm time in CMOS too,
> -			 * so that we will get proper value in RTC_ALM_READ
> -			 */
> -		}
> -		if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
> -							RTC_ALWAYS_BCD) {
> -			if (sec < 60)
> -				sec = bin2bcd(sec);
> -			else
> -				sec = 0xff;
> -
> -			if (min < 60)
> -				min = bin2bcd(min);
> -			else
> -				min = 0xff;
> -
> -			if (hrs < 24)
> -				hrs = bin2bcd(hrs);
> -			else
> -				hrs = 0xff;
> -		}
> -		CMOS_WRITE(hrs, RTC_HOURS_ALARM);
> -		CMOS_WRITE(min, RTC_MINUTES_ALARM);
> -		CMOS_WRITE(sec, RTC_SECONDS_ALARM);
> -		spin_unlock_irq(&rtc_lock);
> -
> -		return 0;
> -	}
> -	case RTC_RD_TIME:	/* Read the time/date from RTC	*/
> -	{
> -		memset(&wtime, 0, sizeof(struct rtc_time));
> -		rtc_get_rtc_time(&wtime);
> -		break;
> -	}
> -	case RTC_SET_TIME:	/* Set the RTC */
> -	{
> -		struct rtc_time rtc_tm;
> -		unsigned char mon, day, hrs, min, sec, leap_yr;
> -		unsigned char save_control, save_freq_select;
> -		unsigned int yrs;
> -#ifdef CONFIG_MACH_DECSTATION
> -		unsigned int real_yrs;
> -#endif
> -
> -		if (!capable(CAP_SYS_TIME))
> -			return -EACCES;
> -
> -		if (copy_from_user(&rtc_tm, (struct rtc_time __user *)arg,
> -				   sizeof(struct rtc_time)))
> -			return -EFAULT;
> -
> -		yrs = rtc_tm.tm_year + 1900;
> -		mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
> -		day = rtc_tm.tm_mday;
> -		hrs = rtc_tm.tm_hour;
> -		min = rtc_tm.tm_min;
> -		sec = rtc_tm.tm_sec;
> -
> -		if (yrs < 1970)
> -			return -EINVAL;
> -
> -		leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
> -
> -		if ((mon > 12) || (day == 0))
> -			return -EINVAL;
> -
> -		if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
> -			return -EINVAL;
> -
> -		if ((hrs >= 24) || (min >= 60) || (sec >= 60))
> -			return -EINVAL;
> -
> -		yrs -= epoch;
> -		if (yrs > 255)		/* They are unsigned */
> -			return -EINVAL;
> -
> -		spin_lock_irq(&rtc_lock);
> -#ifdef CONFIG_MACH_DECSTATION
> -		real_yrs = yrs;
> -		yrs = 72;
> -
> -		/*
> -		 * We want to keep the year set to 73 until March
> -		 * for non-leap years, so that Feb, 29th is handled
> -		 * correctly.
> -		 */
> -		if (!leap_yr && mon < 3) {
> -			real_yrs--;
> -			yrs = 73;
> -		}
> -#endif
> -		/* These limits and adjustments are independent of
> -		 * whether the chip is in binary mode or not.
> -		 */
> -		if (yrs > 169) {
> -			spin_unlock_irq(&rtc_lock);
> -			return -EINVAL;
> -		}
> -		if (yrs >= 100)
> -			yrs -= 100;
> -
> -		if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
> -		    || RTC_ALWAYS_BCD) {
> -			sec = bin2bcd(sec);
> -			min = bin2bcd(min);
> -			hrs = bin2bcd(hrs);
> -			day = bin2bcd(day);
> -			mon = bin2bcd(mon);
> -			yrs = bin2bcd(yrs);
> -		}
> -
> -		save_control = CMOS_READ(RTC_CONTROL);
> -		CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
> -		save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
> -		CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
> -
> -#ifdef CONFIG_MACH_DECSTATION
> -		CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
> -#endif
> -		CMOS_WRITE(yrs, RTC_YEAR);
> -		CMOS_WRITE(mon, RTC_MONTH);
> -		CMOS_WRITE(day, RTC_DAY_OF_MONTH);
> -		CMOS_WRITE(hrs, RTC_HOURS);
> -		CMOS_WRITE(min, RTC_MINUTES);
> -		CMOS_WRITE(sec, RTC_SECONDS);
> -
> -		CMOS_WRITE(save_control, RTC_CONTROL);
> -		CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
> -
> -		spin_unlock_irq(&rtc_lock);
> -		return 0;
> -	}
> -#ifdef RTC_IRQ
> -	case RTC_IRQP_READ:	/* Read the periodic IRQ rate.	*/
> -	{
> -		return put_user(rtc_freq, (unsigned long __user *)arg);
> -	}
> -	case RTC_IRQP_SET:	/* Set periodic IRQ rate.	*/
> -	{
> -		int tmp = 0;
> -		unsigned char val;
> -		/* can be called from isr via rtc_control() */
> -		unsigned long flags;
> -
> -		/*
> -		 * The max we can do is 8192Hz.
> -		 */
> -		if ((arg < 2) || (arg > 8192))
> -			return -EINVAL;
> -		/*
> -		 * We don't really want Joe User generating more
> -		 * than 64Hz of interrupts on a multi-user machine.
> -		 */
> -		if (!kernel && (arg > rtc_max_user_freq) &&
> -					!capable(CAP_SYS_RESOURCE))
> -			return -EACCES;
> -
> -		while (arg > (1<<tmp))
> -			tmp++;
> -
> -		/*
> -		 * Check that the input was really a power of 2.
> -		 */
> -		if (arg != (1<<tmp))
> -			return -EINVAL;
> -
> -		rtc_freq = arg;
> -
> -		spin_lock_irqsave(&rtc_lock, flags);
> -		if (hpet_set_periodic_freq(arg)) {
> -			spin_unlock_irqrestore(&rtc_lock, flags);
> -			return 0;
> -		}
> -
> -		val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
> -		val |= (16 - tmp);
> -		CMOS_WRITE(val, RTC_FREQ_SELECT);
> -		spin_unlock_irqrestore(&rtc_lock, flags);
> -		return 0;
> -	}
> -#endif
> -	case RTC_EPOCH_READ:	/* Read the epoch.	*/
> -	{
> -		return put_user(epoch, (unsigned long __user *)arg);
> -	}
> -	case RTC_EPOCH_SET:	/* Set the epoch.	*/
> -	{
> -		/*
> -		 * There were no RTC clocks before 1900.
> -		 */
> -		if (arg < 1900)
> -			return -EINVAL;
> -
> -		if (!capable(CAP_SYS_TIME))
> -			return -EACCES;
> -
> -		epoch = arg;
> -		return 0;
> -	}
> -	default:
> -		return -ENOTTY;
> -	}
> -	return copy_to_user((void __user *)arg,
> -			    &wtime, sizeof wtime) ? -EFAULT : 0;
> -}
> -
> -static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> -{
> -	long ret;
> -	ret = rtc_do_ioctl(cmd, arg, 0);
> -	return ret;
> -}
> -
> -/*
> - *	We enforce only one user at a time here with the open/close.
> - *	Also clear the previous interrupt data on an open, and clean
> - *	up things on a close.
> - */
> -static int rtc_open(struct inode *inode, struct file *file)
> -{
> -	spin_lock_irq(&rtc_lock);
> -
> -	if (rtc_status & RTC_IS_OPEN)
> -		goto out_busy;
> -
> -	rtc_status |= RTC_IS_OPEN;
> -
> -	rtc_irq_data = 0;
> -	spin_unlock_irq(&rtc_lock);
> -	return 0;
> -
> -out_busy:
> -	spin_unlock_irq(&rtc_lock);
> -	return -EBUSY;
> -}
> -
> -static int rtc_fasync(int fd, struct file *filp, int on)
> -{
> -	return fasync_helper(fd, filp, on, &rtc_async_queue);
> -}
> -
> -static int rtc_release(struct inode *inode, struct file *file)
> -{
> -#ifdef RTC_IRQ
> -	unsigned char tmp;
> -
> -	if (rtc_has_irq == 0)
> -		goto no_irq;
> -
> -	/*
> -	 * Turn off all interrupts once the device is no longer
> -	 * in use, and clear the data.
> -	 */
> -
> -	spin_lock_irq(&rtc_lock);
> -	if (!hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE)) {
> -		tmp = CMOS_READ(RTC_CONTROL);
> -		tmp &=  ~RTC_PIE;
> -		tmp &=  ~RTC_AIE;
> -		tmp &=  ~RTC_UIE;
> -		CMOS_WRITE(tmp, RTC_CONTROL);
> -		CMOS_READ(RTC_INTR_FLAGS);
> -	}
> -	if (rtc_status & RTC_TIMER_ON) {
> -		rtc_status &= ~RTC_TIMER_ON;
> -		del_timer(&rtc_irq_timer);
> -	}
> -	spin_unlock_irq(&rtc_lock);
> -
> -no_irq:
> -#endif
> -
> -	spin_lock_irq(&rtc_lock);
> -	rtc_irq_data = 0;
> -	rtc_status &= ~RTC_IS_OPEN;
> -	spin_unlock_irq(&rtc_lock);
> -
> -	return 0;
> -}
> -
> -#ifdef RTC_IRQ
> -static __poll_t rtc_poll(struct file *file, poll_table *wait)
> -{
> -	unsigned long l;
> -
> -	if (rtc_has_irq == 0)
> -		return 0;
> -
> -	poll_wait(file, &rtc_wait, wait);
> -
> -	spin_lock_irq(&rtc_lock);
> -	l = rtc_irq_data;
> -	spin_unlock_irq(&rtc_lock);
> -
> -	if (l != 0)
> -		return EPOLLIN | EPOLLRDNORM;
> -	return 0;
> -}
> -#endif
> -
> -/*
> - *	The various file operations we support.
> - */
> -
> -static const struct file_operations rtc_fops = {
> -	.owner		= THIS_MODULE,
> -	.llseek		= no_llseek,
> -	.read		= rtc_read,
> -#ifdef RTC_IRQ
> -	.poll		= rtc_poll,
> -#endif
> -	.unlocked_ioctl	= rtc_ioctl,
> -	.open		= rtc_open,
> -	.release	= rtc_release,
> -	.fasync		= rtc_fasync,
> -};
> -
> -static struct miscdevice rtc_dev = {
> -	.minor		= RTC_MINOR,
> -	.name		= "rtc",
> -	.fops		= &rtc_fops,
> -};
> -
> -static resource_size_t rtc_size;
> -
> -static struct resource * __init rtc_request_region(resource_size_t size)
> -{
> -	struct resource *r;
> -
> -	if (RTC_IOMAPPED)
> -		r = request_region(RTC_PORT(0), size, "rtc");
> -	else
> -		r = request_mem_region(RTC_PORT(0), size, "rtc");
> -
> -	if (r)
> -		rtc_size = size;
> -
> -	return r;
> -}
> -
> -static void rtc_release_region(void)
> -{
> -	if (RTC_IOMAPPED)
> -		release_region(RTC_PORT(0), rtc_size);
> -	else
> -		release_mem_region(RTC_PORT(0), rtc_size);
> -}
> -
> -static int __init rtc_init(void)
> -{
> -#ifdef CONFIG_PROC_FS
> -	struct proc_dir_entry *ent;
> -#endif
> -#if defined(__alpha__) || defined(__mips__)
> -	unsigned int year, ctrl;
> -	char *guess = NULL;
> -#endif
> -#ifdef CONFIG_SPARC32
> -	struct device_node *ebus_dp;
> -	struct platform_device *op;
> -#else
> -	void *r;
> -#ifdef RTC_IRQ
> -	irq_handler_t rtc_int_handler_ptr;
> -#endif
> -#endif
> -
> -#ifdef CONFIG_SPARC32
> -	for_each_node_by_name(ebus_dp, "ebus") {
> -		struct device_node *dp;
> -		for_each_child_of_node(ebus_dp, dp) {
> -			if (of_node_name_eq(dp, "rtc")) {
> -				op = of_find_device_by_node(dp);
> -				if (op) {
> -					rtc_port = op->resource[0].start;
> -					rtc_irq = op->irqs[0];
> -					goto found;
> -				}
> -			}
> -		}
> -	}
> -	rtc_has_irq = 0;
> -	printk(KERN_ERR "rtc_init: no PC rtc found\n");
> -	return -EIO;
> -
> -found:
> -	if (!rtc_irq) {
> -		rtc_has_irq = 0;
> -		goto no_irq;
> -	}
> -
> -	/*
> -	 * XXX Interrupt pin #7 in Espresso is shared between RTC and
> -	 * PCI Slot 2 INTA# (and some INTx# in Slot 1).
> -	 */
> -	if (request_irq(rtc_irq, rtc_interrupt, IRQF_SHARED, "rtc",
> -			(void *)&rtc_port)) {
> -		rtc_has_irq = 0;
> -		printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
> -		return -EIO;
> -	}
> -no_irq:
> -#else
> -	r = rtc_request_region(RTC_IO_EXTENT);
> -
> -	/*
> -	 * If we've already requested a smaller range (for example, because
> -	 * PNPBIOS or ACPI told us how the device is configured), the request
> -	 * above might fail because it's too big.
> -	 *
> -	 * If so, request just the range we actually use.
> -	 */
> -	if (!r)
> -		r = rtc_request_region(RTC_IO_EXTENT_USED);
> -	if (!r) {
> -#ifdef RTC_IRQ
> -		rtc_has_irq = 0;
> -#endif
> -		printk(KERN_ERR "rtc: I/O resource %lx is not free.\n",
> -		       (long)(RTC_PORT(0)));
> -		return -EIO;
> -	}
> -
> -#ifdef RTC_IRQ
> -	if (is_hpet_enabled()) {
> -		int err;
> -
> -		rtc_int_handler_ptr = hpet_rtc_interrupt;
> -		err = hpet_register_irq_handler(rtc_interrupt);
> -		if (err != 0) {
> -			printk(KERN_WARNING "hpet_register_irq_handler failed "
> -					"in rtc_init().");
> -			return err;
> -		}
> -	} else {
> -		rtc_int_handler_ptr = rtc_interrupt;
> -	}
> -
> -	if (request_irq(RTC_IRQ, rtc_int_handler_ptr, 0, "rtc", NULL)) {
> -		/* Yeah right, seeing as irq 8 doesn't even hit the bus. */
> -		rtc_has_irq = 0;
> -		printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
> -		rtc_release_region();
> -
> -		return -EIO;
> -	}
> -	hpet_rtc_timer_init();
> -
> -#endif
> -
> -#endif /* CONFIG_SPARC32 vs. others */
> -
> -	if (misc_register(&rtc_dev)) {
> -#ifdef RTC_IRQ
> -		free_irq(RTC_IRQ, NULL);
> -		hpet_unregister_irq_handler(rtc_interrupt);
> -		rtc_has_irq = 0;
> -#endif
> -		rtc_release_region();
> -		return -ENODEV;
> -	}
> -
> -#ifdef CONFIG_PROC_FS
> -	ent = proc_create_single("driver/rtc", 0, NULL, rtc_proc_show);
> -	if (!ent)
> -		printk(KERN_WARNING "rtc: Failed to register with procfs.\n");
> -#endif
> -
> -#if defined(__alpha__) || defined(__mips__)
> -	rtc_freq = HZ;
> -
> -	/* Each operating system on an Alpha uses its own epoch.
> -	   Let's try to guess which one we are using now. */
> -
> -	if (rtc_is_updating() != 0)
> -		msleep(20);
> -
> -	spin_lock_irq(&rtc_lock);
> -	year = CMOS_READ(RTC_YEAR);
> -	ctrl = CMOS_READ(RTC_CONTROL);
> -	spin_unlock_irq(&rtc_lock);
> -
> -	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
> -		year = bcd2bin(year);       /* This should never happen... */
> -
> -	if (year < 20) {
> -		epoch = 2000;
> -		guess = "SRM (post-2000)";
> -	} else if (year >= 20 && year < 48) {
> -		epoch = 1980;
> -		guess = "ARC console";
> -	} else if (year >= 48 && year < 72) {
> -		epoch = 1952;
> -		guess = "Digital UNIX";
> -#if defined(__mips__)
> -	} else if (year >= 72 && year < 74) {
> -		epoch = 2000;
> -		guess = "Digital DECstation";
> -#else
> -	} else if (year >= 70) {
> -		epoch = 1900;
> -		guess = "Standard PC (1900)";
> -#endif
> -	}
> -	if (guess)
> -		printk(KERN_INFO "rtc: %s epoch (%lu) detected\n",
> -			guess, epoch);
> -#endif
> -#ifdef RTC_IRQ
> -	if (rtc_has_irq == 0)
> -		goto no_irq2;
> -
> -	spin_lock_irq(&rtc_lock);
> -	rtc_freq = 1024;
> -	if (!hpet_set_periodic_freq(rtc_freq)) {
> -		/*
> -		 * Initialize periodic frequency to CMOS reset default,
> -		 * which is 1024Hz
> -		 */
> -		CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06),
> -			   RTC_FREQ_SELECT);
> -	}
> -	spin_unlock_irq(&rtc_lock);
> -no_irq2:
> -#endif
> -
> -	(void) init_sysctl();
> -
> -	printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
> -
> -	return 0;
> -}
> -
> -static void __exit rtc_exit(void)
> -{
> -	cleanup_sysctl();
> -	remove_proc_entry("driver/rtc", NULL);
> -	misc_deregister(&rtc_dev);
> -
> -#ifdef CONFIG_SPARC32
> -	if (rtc_has_irq)
> -		free_irq(rtc_irq, &rtc_port);
> -#else
> -	rtc_release_region();
> -#ifdef RTC_IRQ
> -	if (rtc_has_irq) {
> -		free_irq(RTC_IRQ, NULL);
> -		hpet_unregister_irq_handler(hpet_rtc_interrupt);
> -	}
> -#endif
> -#endif /* CONFIG_SPARC32 */
> -}
> -
> -module_init(rtc_init);
> -module_exit(rtc_exit);
> -
> -#ifdef RTC_IRQ
> -/*
> - *	At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
> - *	(usually during an IDE disk interrupt, with IRQ unmasking off)
> - *	Since the interrupt handler doesn't get called, the IRQ status
> - *	byte doesn't get read, and the RTC stops generating interrupts.
> - *	A timer is set, and will call this function if/when that happens.
> - *	To get it out of this stalled state, we just read the status.
> - *	At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
> - *	(You *really* shouldn't be trying to use a non-realtime system
> - *	for something that requires a steady > 1KHz signal anyways.)
> - */
> -
> -static void rtc_dropped_irq(struct timer_list *unused)
> -{
> -	unsigned long freq;
> -
> -	spin_lock_irq(&rtc_lock);
> -
> -	if (hpet_rtc_dropped_irq()) {
> -		spin_unlock_irq(&rtc_lock);
> -		return;
> -	}
> -
> -	/* Just in case someone disabled the timer from behind our back... */
> -	if (rtc_status & RTC_TIMER_ON)
> -		mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
> -
> -	rtc_irq_data += ((rtc_freq/HZ)<<8);
> -	rtc_irq_data &= ~0xff;
> -	rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);	/* restart */
> -
> -	freq = rtc_freq;
> -
> -	spin_unlock_irq(&rtc_lock);
> -
> -	printk_ratelimited(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
> -			   freq);
> -
> -	/* Now we have new data */
> -	wake_up_interruptible(&rtc_wait);
> -
> -	kill_fasync(&rtc_async_queue, SIGIO, POLL_IN);
> -}
> -#endif
> -
> -#ifdef CONFIG_PROC_FS
> -/*
> - *	Info exported via "/proc/driver/rtc".
> - */
> -
> -static int rtc_proc_show(struct seq_file *seq, void *v)
> -{
> -#define YN(bit) ((ctrl & bit) ? "yes" : "no")
> -#define NY(bit) ((ctrl & bit) ? "no" : "yes")
> -	struct rtc_time tm;
> -	unsigned char batt, ctrl;
> -	unsigned long freq;
> -
> -	spin_lock_irq(&rtc_lock);
> -	batt = CMOS_READ(RTC_VALID) & RTC_VRT;
> -	ctrl = CMOS_READ(RTC_CONTROL);
> -	freq = rtc_freq;
> -	spin_unlock_irq(&rtc_lock);
> -
> -
> -	rtc_get_rtc_time(&tm);
> -
> -	/*
> -	 * There is no way to tell if the luser has the RTC set for local
> -	 * time or for Universal Standard Time (GMT). Probably local though.
> -	 */
> -	seq_printf(seq,
> -		   "rtc_time\t: %ptRt\n"
> -		   "rtc_date\t: %ptRd\n"
> -		   "rtc_epoch\t: %04lu\n",
> -		   &tm, &tm, epoch);
> -
> -	get_rtc_alm_time(&tm);
> -
> -	/*
> -	 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
> -	 * match any value for that particular field. Values that are
> -	 * greater than a valid time, but less than 0xc0 shouldn't appear.
> -	 */
> -	seq_puts(seq, "alarm\t\t: ");
> -	if (tm.tm_hour <= 24)
> -		seq_printf(seq, "%02d:", tm.tm_hour);
> -	else
> -		seq_puts(seq, "**:");
> -
> -	if (tm.tm_min <= 59)
> -		seq_printf(seq, "%02d:", tm.tm_min);
> -	else
> -		seq_puts(seq, "**:");
> -
> -	if (tm.tm_sec <= 59)
> -		seq_printf(seq, "%02d\n", tm.tm_sec);
> -	else
> -		seq_puts(seq, "**\n");
> -
> -	seq_printf(seq,
> -		   "DST_enable\t: %s\n"
> -		   "BCD\t\t: %s\n"
> -		   "24hr\t\t: %s\n"
> -		   "square_wave\t: %s\n"
> -		   "alarm_IRQ\t: %s\n"
> -		   "update_IRQ\t: %s\n"
> -		   "periodic_IRQ\t: %s\n"
> -		   "periodic_freq\t: %ld\n"
> -		   "batt_status\t: %s\n",
> -		   YN(RTC_DST_EN),
> -		   NY(RTC_DM_BINARY),
> -		   YN(RTC_24H),
> -		   YN(RTC_SQWE),
> -		   YN(RTC_AIE),
> -		   YN(RTC_UIE),
> -		   YN(RTC_PIE),
> -		   freq,
> -		   batt ? "okay" : "dead");
> -
> -	return  0;
> -#undef YN
> -#undef NY
> -}
> -#endif
> -
> -static void rtc_get_rtc_time(struct rtc_time *rtc_tm)
> -{
> -	unsigned long uip_watchdog = jiffies, flags;
> -	unsigned char ctrl;
> -#ifdef CONFIG_MACH_DECSTATION
> -	unsigned int real_year;
> -#endif
> -
> -	/*
> -	 * read RTC once any update in progress is done. The update
> -	 * can take just over 2ms. We wait 20ms. There is no need to
> -	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
> -	 * If you need to know *exactly* when a second has started, enable
> -	 * periodic update complete interrupts, (via ioctl) and then
> -	 * immediately read /dev/rtc which will block until you get the IRQ.
> -	 * Once the read clears, read the RTC time (again via ioctl). Easy.
> -	 */
> -
> -	while (rtc_is_updating() != 0 &&
> -	       time_before(jiffies, uip_watchdog + 2*HZ/100))
> -		cpu_relax();
> -
> -	/*
> -	 * Only the values that we read from the RTC are set. We leave
> -	 * tm_wday, tm_yday and tm_isdst untouched. Note that while the
> -	 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
> -	 * only updated by the RTC when initially set to a non-zero value.
> -	 */
> -	spin_lock_irqsave(&rtc_lock, flags);
> -	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
> -	rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
> -	rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
> -	rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
> -	rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
> -	rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
> -	/* Only set from 2.6.16 onwards */
> -	rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);
> -
> -#ifdef CONFIG_MACH_DECSTATION
> -	real_year = CMOS_READ(RTC_DEC_YEAR);
> -#endif
> -	ctrl = CMOS_READ(RTC_CONTROL);
> -	spin_unlock_irqrestore(&rtc_lock, flags);
> -
> -	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
> -		rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
> -		rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
> -		rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
> -		rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
> -		rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
> -		rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
> -		rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
> -	}
> -
> -#ifdef CONFIG_MACH_DECSTATION
> -	rtc_tm->tm_year += real_year - 72;
> -#endif
> -
> -	/*
> -	 * Account for differences between how the RTC uses the values
> -	 * and how they are defined in a struct rtc_time;
> -	 */
> -	rtc_tm->tm_year += epoch - 1900;
> -	if (rtc_tm->tm_year <= 69)
> -		rtc_tm->tm_year += 100;
> -
> -	rtc_tm->tm_mon--;
> -}
> -
> -static void get_rtc_alm_time(struct rtc_time *alm_tm)
> -{
> -	unsigned char ctrl;
> -
> -	/*
> -	 * Only the values that we read from the RTC are set. That
> -	 * means only tm_hour, tm_min, and tm_sec.
> -	 */
> -	spin_lock_irq(&rtc_lock);
> -	alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
> -	alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
> -	alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
> -	ctrl = CMOS_READ(RTC_CONTROL);
> -	spin_unlock_irq(&rtc_lock);
> -
> -	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
> -		alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
> -		alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
> -		alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
> -	}
> -}
> -
> -#ifdef RTC_IRQ
> -/*
> - * Used to disable/enable interrupts for any one of UIE, AIE, PIE.
> - * Rumour has it that if you frob the interrupt enable/disable
> - * bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
> - * ensure you actually start getting interrupts. Probably for
> - * compatibility with older/broken chipset RTC implementations.
> - * We also clear out any old irq data after an ioctl() that
> - * meddles with the interrupt enable/disable bits.
> - */
> -
> -static void mask_rtc_irq_bit_locked(unsigned char bit)
> -{
> -	unsigned char val;
> -
> -	if (hpet_mask_rtc_irq_bit(bit))
> -		return;
> -	val = CMOS_READ(RTC_CONTROL);
> -	val &=  ~bit;
> -	CMOS_WRITE(val, RTC_CONTROL);
> -	CMOS_READ(RTC_INTR_FLAGS);
> -
> -	rtc_irq_data = 0;
> -}
> -
> -static void set_rtc_irq_bit_locked(unsigned char bit)
> -{
> -	unsigned char val;
> -
> -	if (hpet_set_rtc_irq_bit(bit))
> -		return;
> -	val = CMOS_READ(RTC_CONTROL);
> -	val |= bit;
> -	CMOS_WRITE(val, RTC_CONTROL);
> -	CMOS_READ(RTC_INTR_FLAGS);
> -
> -	rtc_irq_data = 0;
> -}
> -#endif
> -
> -MODULE_AUTHOR("Paul Gortmaker");
> -MODULE_LICENSE("GPL");
> -MODULE_ALIAS_MISCDEV(RTC_MINOR);
> -- 
> 2.20.0
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com