Patchwork add rtc platform driver for EFI

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Submitter dann frazier
Date Jan. 9, 2009, 12:56 a.m.
Message ID <20090109005644.GH32403@ldl.fc.hp.com>
Download mbox | patch
Permalink /patch/17450/
State Changes Requested
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dann frazier - Jan. 9, 2009, 12:56 a.m.
Munge Stephane Eranian's efirtc.c code into an rtc platform driver

Signed-off-by: dann frazier <dannf@hp.com>
---
 arch/ia64/kernel/time.c |   18 +++
 drivers/rtc/Kconfig     |   10 ++
 drivers/rtc/Makefile    |    1 +
 drivers/rtc/rtc-efi.c   |  294 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 323 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-efi.c
Alessandro Zummo - Jan. 9, 2009, 2:27 a.m.
On Thu, 8 Jan 2009 17:56:45 -0700
dann frazier <dannf@hp.com> wrote:

 a few comments below. please
 also check http://groups.google.com/group/rtc-linux/web/checklist

> Munge Stephane Eranian's efirtc.c code into an rtc platform driver
> 
> Signed-off-by: dann frazier <dannf@hp.com>
> ---
>  arch/ia64/kernel/time.c |   18 +++
>  drivers/rtc/Kconfig     |   10 ++
>  drivers/rtc/Makefile    |    1 +
>  drivers/rtc/rtc-efi.c   |  294 +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 323 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-efi.c
> 
> diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
> index f0ebb34..9ed5ba0 100644
> --- a/arch/ia64/kernel/time.c
> +++ b/arch/ia64/kernel/time.c
> @@ -20,6 +20,7 @@
>  #include <linux/efi.h>
>  #include <linux/timex.h>
>  #include <linux/clocksource.h>
> +#include <linux/platform_device.h>
>  
>  #include <asm/machvec.h>
>  #include <asm/delay.h>
> @@ -405,6 +406,23 @@ static struct irqaction timer_irqaction = {
>  	.name =		"timer"
>  };
>  
> +struct platform_device rtc_efi_dev = {
> +	.name = "rtc-efi",
> +	.id = -1,
> +};
> +
> +static int __init rtc_init(void)
> +{
> +	int ret;
> +	ret = platform_device_register(&rtc_efi_dev);
> +	if (ret < 0)
> +		printk(KERN_ERR "unable to register rtc device...\n");
> +       
> +	/* not necessarily an error */
> +	return 0;
> +}
> +module_init(rtc_init);
> +
>  void __init
>  time_init (void)
>  {
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 165a818..37ce842 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -433,6 +433,16 @@ config RTC_DRV_DS1742
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-ds1742.
>  
> +config RTC_DRV_EFI
> +	tristate "EFI RTC"
> +	depends on IA64
> +	help
> +	  If you say yes here you will get support for the EFI
> +	  Real Time Clock.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-efi.
> +
>  config RTC_DRV_STK17TA8
>  	tristate "Simtek STK17TA8"
>  	depends on RTC_CLASS
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 6e79c91..29db401 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
>  obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
>  obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
>  obj-$(CONFIG_RTC_DRV_DS3234)	+= rtc-ds3234.o
> +obj-$(CONFIG_RTC_DRV_EFI)	+= rtc-efi.o
>  obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
>  obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
> diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
> new file mode 100644
> index 0000000..2386da0
> --- /dev/null
> +++ b/drivers/rtc/rtc-efi.c
> @@ -0,0 +1,294 @@
> +/*
> + * rtc-efi: RTC Class Driver for EFI-based systems
> + *
> + * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
> + *
> + * Author: dann frazier <dannf@hp.com>
> + * Based on efirtc.c by Stephane Eranian
> + *
> + *  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.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/time.h>
> +#include <linux/platform_device.h>
> +
> +#include <linux/efi.h>
> +
> +#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
> +/*
> + * EFI Epoch is 1/1/1998
> + */
> +#define EFI_RTC_EPOCH		1998
> +
> +#define is_leap(year) \
> +	((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
> +
> +struct efi_rtc {
> +	struct rtc_device *rtc;
> +	spinlock_t lock;
> +};
> +
> +static const unsigned short int __mon_yday[2][13] =
> +{
> +	/* Normal years.  */
> +	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
> +	/* Leap years.  */
> +	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
> +};

 please check drivers/rtc/rtc-lib.c

> +/*
> + * returns day of the year [0-365]
> + */
> +static inline int
> +compute_yday(efi_time_t *eft)
> +{
> +	/* efi_time_t.month is in the [1-12] so, we need -1 */
> +	return  __mon_yday[is_leap(eft->year)][eft->month-1] + eft->day - 1;
> +}
> +/*
> + * returns day of the week [0-6] 0=Sunday
> + *
> + * Don't try to provide a year that's before 1998, please !
> + */
> +static int
> +compute_wday(efi_time_t *eft)
> +{
> +	int y;
> +	int ndays = 0;
> +
> +	if (eft->year < 1998) {
> +		printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
> +		return -1;
> +	}
> +
> +	for (y = EFI_RTC_EPOCH; y < eft->year; y++)
> +		ndays += 365 + (is_leap(y) ? 1 : 0);
> +
> +	ndays += compute_yday(eft);
> +
> +	/*
> +	 * 4=1/1/1998 was a Thursday
> +	 */
> +	return (ndays + 4) % 7;
> +}
> +
> +static void
> +convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
> +{
> +
> +	eft->year	= wtime->tm_year + 1900;
> +	eft->month	= wtime->tm_mon + 1;
> +	eft->day	= wtime->tm_mday;
> +	eft->hour	= wtime->tm_hour;
> +	eft->minute	= wtime->tm_min;
> +	eft->second 	= wtime->tm_sec;
> +	eft->nanosecond = 0;
> +	eft->daylight	= wtime->tm_isdst ? EFI_ISDST : 0;
> +	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
> +}
> +
> +static void
> +convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
> +{
> +	memset(wtime, 0, sizeof(*wtime));
> +	wtime->tm_sec  = eft->second;
> +	wtime->tm_min  = eft->minute;
> +	wtime->tm_hour = eft->hour;
> +	wtime->tm_mday = eft->day;
> +	wtime->tm_mon  = eft->month - 1;
> +	wtime->tm_year = eft->year - 1900;
> +
> +	/* day of the week [0-6], Sunday=0 */
> +	wtime->tm_wday = compute_wday(eft);
> +
> +	/* day in the year [1-365]*/
> +	wtime->tm_yday = compute_yday(eft);
> +
> +
> +	switch (eft->daylight & EFI_ISDST) {
> +	case EFI_ISDST:
> +		wtime->tm_isdst = 1;
> +		break;
> +	case EFI_TIME_ADJUST_DAYLIGHT:
> +		wtime->tm_isdst = 0;
> +		break;
> +	default:
> +		wtime->tm_isdst = -1;
> +	}
> +}
> +
> +static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> +{
> +	struct efi_rtc *p = dev_get_drvdata(dev);
> +	efi_time_t eft;
> +	efi_status_t status;
> +	unsigned long flags;
> +
> +	lock_kernel();
> +
> +	spin_lock_irqsave(&p->lock, flags);

 you don't need your own lock, the rtc subsystem provides
 ops locking.

> +	/*
> +	 * As of EFI v1.10, this call always returns an unsupported status
> +	 */
> +	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
> +				     (efi_bool_t *)&wkalrm->pending, &eft);
> +	spin_unlock_irqrestore(&p->lock, flags);
> +
> +	unlock_kernel();
> +
> +	if (status != EFI_SUCCESS)
> +		return -EINVAL;
> +
> +	convert_from_efi_time(&eft, &wkalrm->time);
> +
> +	return 0;

 use return rtc_valid_tm

> +}
> +
> +static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> +{
> +	struct efi_rtc *p = dev_get_drvdata(dev);
> +	efi_time_t eft;
> +	efi_status_t status;
> +	unsigned long flags;
> +
> +	convert_to_efi_time(&wkalrm->time, &eft);
> +
> +	lock_kernel();
> +
> +	spin_lock_irqsave(&p->lock, flags);
> +	/*
> +	 * XXX Fixme:
> +	 * As of EFI 0.92 with the firmware I have on my
> +	 * machine this call does not seem to work quite
> +	 * right
> +	 *
> +	 * As of v1.10, this call always returns an unsupported status
> +	 */
> +	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
> +	spin_unlock_irqrestore(&p->lock, flags);
> +
> +	unlock_kernel();
> +
> +	printk(KERN_WARNING "write status is %d\n", (int)status);
> +
> +	return status == EFI_SUCCESS ? 0 : -EINVAL;
> +}
> +
> +static int efi_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct efi_rtc *p = dev_get_drvdata(dev);
> +	unsigned long flags;
> +	efi_status_t status;
> +	efi_time_t eft;
> +	efi_time_cap_t cap;
> +
> +	lock_kernel();
> +
> +	spin_lock_irqsave(&p->lock, flags);
> +	status = efi.get_time(&eft, &cap);
> +	spin_unlock_irqrestore(&p->lock, flags);
> +
> +	unlock_kernel();
> +
> +	if (status != EFI_SUCCESS) {
> +		/* should never happen */
> +		printk(KERN_ERR "efitime: can't read time\n");
> +		return -EINVAL;
> +	}
> +
> +	convert_from_efi_time(&eft, tm);
> +
> +	return 0;

 use rtc_valid_tm

> +}
> +
> +static int efi_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct efi_rtc *p = dev_get_drvdata(dev);
> +	unsigned long flags;
> +	efi_status_t status;
> +	efi_time_t eft;
> +
> +	convert_to_efi_time(tm, &eft);
> +
> +	lock_kernel();
> +
> +	spin_lock_irqsave(&p->lock, flags);
> +	status = efi.set_time(&eft);
> +	spin_unlock_irqrestore(&p->lock, flags);
> +
> +	unlock_kernel();
> +
> +	return status == EFI_SUCCESS ? 0 : -EINVAL;
> +}
> +
> +static const struct rtc_class_ops efi_rtc_ops = {
> +	.read_time = efi_read_time,
> +	.set_time = efi_set_time,
> +	.read_alarm = efi_read_alarm,
> +	.set_alarm = efi_set_alarm,
> +};
> +
> +static int __devinit efi_rtc_probe(struct platform_device *dev)
> +{
> +	struct efi_rtc *p;
> +
> +	p = kzalloc(sizeof (*p), GFP_KERNEL);
> +	if (!p)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&p->lock);
> +
> +	p->rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
> +					THIS_MODULE);
> +	if (IS_ERR(p->rtc)) {
> +		int err = PTR_ERR(p->rtc);
> +		kfree(p);
> +		return err;
> +	}
> +
> +	platform_set_drvdata(dev, p);
> +
> +	return 0;
> +}
> +
> +static int __devexit efi_rtc_remove(struct platform_device *dev)
> +{
> +	struct efi_rtc *p = platform_get_drvdata(dev);
> +
> +	rtc_device_unregister(p->rtc);
> +	kfree(p);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver efi_rtc_driver = {
> +	.driver = {
> +		.name = "rtc-efi",
> +		.owner = THIS_MODULE,
> +	},
> +	.probe = efi_rtc_probe,
> +	.remove = __devexit_p(efi_rtc_remove),
> +};
> +
> +static int __init efi_rtc_init(void)
> +{
> +	return platform_driver_register(&efi_rtc_driver);

 you can probably use platform_driver_probe

> +}
> +
> +static void __exit efi_rtc_exit(void)
> +{
> +	platform_driver_unregister(&efi_rtc_driver);
> +}
> +
> +module_init(efi_rtc_init);
> +module_exit(efi_rtc_exit);
> +
> +MODULE_AUTHOR("dann frazier <dannf@hp.com>");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("EFI RTC driver");
> -- 
> 1.5.6.5
> 
> 
> >
dann frazier - Jan. 9, 2009, 9:34 p.m.
On Fri, Jan 09, 2009 at 03:27:29AM +0100, Alessandro Zummo wrote:
> On Thu, 8 Jan 2009 17:56:45 -0700
> dann frazier <dannf@hp.com> wrote:
> 
>  a few comments below. please
>  also check http://groups.google.com/group/rtc-linux/web/checklist

Thanks for the pointer. I _think_ I comply, after fixing the
individual issues you brought up below. 

One question is with:
  "do not kfree() what's returned by rtc_device_register()"

I do kfree the return if it comes back as an error - is that still
correct?

> > Munge Stephane Eranian's efirtc.c code into an rtc platform driver
> > 
> > Signed-off-by: dann frazier <dannf@hp.com>
> > ---
> >  arch/ia64/kernel/time.c |   18 +++
> >  drivers/rtc/Kconfig     |   10 ++
> >  drivers/rtc/Makefile    |    1 +
> >  drivers/rtc/rtc-efi.c   |  294 +++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 323 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/rtc/rtc-efi.c
> > 
> > diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
> > index f0ebb34..9ed5ba0 100644
> > --- a/arch/ia64/kernel/time.c
> > +++ b/arch/ia64/kernel/time.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/efi.h>
> >  #include <linux/timex.h>
> >  #include <linux/clocksource.h>
> > +#include <linux/platform_device.h>
> >  
> >  #include <asm/machvec.h>
> >  #include <asm/delay.h>
> > @@ -405,6 +406,23 @@ static struct irqaction timer_irqaction = {
> >  	.name =		"timer"
> >  };
> >  
> > +struct platform_device rtc_efi_dev = {
> > +	.name = "rtc-efi",
> > +	.id = -1,
> > +};
> > +
> > +static int __init rtc_init(void)
> > +{
> > +	int ret;
> > +	ret = platform_device_register(&rtc_efi_dev);
> > +	if (ret < 0)
> > +		printk(KERN_ERR "unable to register rtc device...\n");
> > +       
> > +	/* not necessarily an error */
> > +	return 0;
> > +}
> > +module_init(rtc_init);
> > +
> >  void __init
> >  time_init (void)
> >  {
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index 165a818..37ce842 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -433,6 +433,16 @@ config RTC_DRV_DS1742
> >  	  This driver can also be built as a module. If so, the module
> >  	  will be called rtc-ds1742.
> >  
> > +config RTC_DRV_EFI
> > +	tristate "EFI RTC"
> > +	depends on IA64
> > +	help
> > +	  If you say yes here you will get support for the EFI
> > +	  Real Time Clock.
> > +
> > +	  This driver can also be built as a module. If so, the module
> > +	  will be called rtc-efi.
> > +
> >  config RTC_DRV_STK17TA8
> >  	tristate "Simtek STK17TA8"
> >  	depends on RTC_CLASS
> > diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> > index 6e79c91..29db401 100644
> > --- a/drivers/rtc/Makefile
> > +++ b/drivers/rtc/Makefile
> > @@ -34,6 +34,7 @@ obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
> >  obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
> >  obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
> >  obj-$(CONFIG_RTC_DRV_DS3234)	+= rtc-ds3234.o
> > +obj-$(CONFIG_RTC_DRV_EFI)	+= rtc-efi.o
> >  obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
> >  obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
> >  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
> > diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
> > new file mode 100644
> > index 0000000..2386da0
> > --- /dev/null
> > +++ b/drivers/rtc/rtc-efi.c
> > @@ -0,0 +1,294 @@
> > +/*
> > + * rtc-efi: RTC Class Driver for EFI-based systems
> > + *
> > + * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
> > + *
> > + * Author: dann frazier <dannf@hp.com>
> > + * Based on efirtc.c by Stephane Eranian
> > + *
> > + *  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.
> > + *
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/time.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <linux/efi.h>
> > +
> > +#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
> > +/*
> > + * EFI Epoch is 1/1/1998
> > + */
> > +#define EFI_RTC_EPOCH		1998
> > +
> > +#define is_leap(year) \
> > +	((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
> > +
> > +struct efi_rtc {
> > +	struct rtc_device *rtc;
> > +	spinlock_t lock;
> > +};
> > +
> > +static const unsigned short int __mon_yday[2][13] =
> > +{
> > +	/* Normal years.  */
> > +	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
> > +	/* Leap years.  */
> > +	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
> > +};
> 
>  please check drivers/rtc/rtc-lib.c

ah nice, fixed.

> > +/*
> > + * returns day of the year [0-365]
> > + */
> > +static inline int
> > +compute_yday(efi_time_t *eft)
> > +{
> > +	/* efi_time_t.month is in the [1-12] so, we need -1 */
> > +	return  __mon_yday[is_leap(eft->year)][eft->month-1] + eft->day - 1;
> > +}
> > +/*
> > + * returns day of the week [0-6] 0=Sunday
> > + *
> > + * Don't try to provide a year that's before 1998, please !
> > + */
> > +static int
> > +compute_wday(efi_time_t *eft)
> > +{
> > +	int y;
> > +	int ndays = 0;
> > +
> > +	if (eft->year < 1998) {
> > +		printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
> > +		return -1;
> > +	}
> > +
> > +	for (y = EFI_RTC_EPOCH; y < eft->year; y++)
> > +		ndays += 365 + (is_leap(y) ? 1 : 0);
> > +
> > +	ndays += compute_yday(eft);
> > +
> > +	/*
> > +	 * 4=1/1/1998 was a Thursday
> > +	 */
> > +	return (ndays + 4) % 7;
> > +}
> > +
> > +static void
> > +convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
> > +{
> > +
> > +	eft->year	= wtime->tm_year + 1900;
> > +	eft->month	= wtime->tm_mon + 1;
> > +	eft->day	= wtime->tm_mday;
> > +	eft->hour	= wtime->tm_hour;
> > +	eft->minute	= wtime->tm_min;
> > +	eft->second 	= wtime->tm_sec;
> > +	eft->nanosecond = 0;
> > +	eft->daylight	= wtime->tm_isdst ? EFI_ISDST : 0;
> > +	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
> > +}
> > +
> > +static void
> > +convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
> > +{
> > +	memset(wtime, 0, sizeof(*wtime));
> > +	wtime->tm_sec  = eft->second;
> > +	wtime->tm_min  = eft->minute;
> > +	wtime->tm_hour = eft->hour;
> > +	wtime->tm_mday = eft->day;
> > +	wtime->tm_mon  = eft->month - 1;
> > +	wtime->tm_year = eft->year - 1900;
> > +
> > +	/* day of the week [0-6], Sunday=0 */
> > +	wtime->tm_wday = compute_wday(eft);
> > +
> > +	/* day in the year [1-365]*/
> > +	wtime->tm_yday = compute_yday(eft);
> > +
> > +
> > +	switch (eft->daylight & EFI_ISDST) {
> > +	case EFI_ISDST:
> > +		wtime->tm_isdst = 1;
> > +		break;
> > +	case EFI_TIME_ADJUST_DAYLIGHT:
> > +		wtime->tm_isdst = 0;
> > +		break;
> > +	default:
> > +		wtime->tm_isdst = -1;
> > +	}
> > +}
> > +
> > +static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> > +{
> > +	struct efi_rtc *p = dev_get_drvdata(dev);
> > +	efi_time_t eft;
> > +	efi_status_t status;
> > +	unsigned long flags;
> > +
> > +	lock_kernel();
> > +
> > +	spin_lock_irqsave(&p->lock, flags);
> 
>  you don't need your own lock, the rtc subsystem provides
>  ops locking.

cool, removed.

> > +	/*
> > +	 * As of EFI v1.10, this call always returns an unsupported status
> > +	 */
> > +	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
> > +				     (efi_bool_t *)&wkalrm->pending, &eft);
> > +	spin_unlock_irqrestore(&p->lock, flags);
> > +
> > +	unlock_kernel();
> > +
> > +	if (status != EFI_SUCCESS)
> > +		return -EINVAL;
> > +
> > +	convert_from_efi_time(&eft, &wkalrm->time);
> > +
> > +	return 0;
> 
>  use return rtc_valid_tm

fixed

> > +}
> > +
> > +static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> > +{
> > +	struct efi_rtc *p = dev_get_drvdata(dev);
> > +	efi_time_t eft;
> > +	efi_status_t status;
> > +	unsigned long flags;
> > +
> > +	convert_to_efi_time(&wkalrm->time, &eft);
> > +
> > +	lock_kernel();
> > +
> > +	spin_lock_irqsave(&p->lock, flags);
> > +	/*
> > +	 * XXX Fixme:
> > +	 * As of EFI 0.92 with the firmware I have on my
> > +	 * machine this call does not seem to work quite
> > +	 * right
> > +	 *
> > +	 * As of v1.10, this call always returns an unsupported status
> > +	 */
> > +	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
> > +	spin_unlock_irqrestore(&p->lock, flags);
> > +
> > +	unlock_kernel();
> > +
> > +	printk(KERN_WARNING "write status is %d\n", (int)status);
> > +
> > +	return status == EFI_SUCCESS ? 0 : -EINVAL;
> > +}
> > +
> > +static int efi_read_time(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct efi_rtc *p = dev_get_drvdata(dev);
> > +	unsigned long flags;
> > +	efi_status_t status;
> > +	efi_time_t eft;
> > +	efi_time_cap_t cap;
> > +
> > +	lock_kernel();
> > +
> > +	spin_lock_irqsave(&p->lock, flags);
> > +	status = efi.get_time(&eft, &cap);
> > +	spin_unlock_irqrestore(&p->lock, flags);
> > +
> > +	unlock_kernel();
> > +
> > +	if (status != EFI_SUCCESS) {
> > +		/* should never happen */
> > +		printk(KERN_ERR "efitime: can't read time\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	convert_from_efi_time(&eft, tm);
> > +
> > +	return 0;
> 
>  use rtc_valid_tm

fixed

> > +}
> > +
> > +static int efi_set_time(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct efi_rtc *p = dev_get_drvdata(dev);
> > +	unsigned long flags;
> > +	efi_status_t status;
> > +	efi_time_t eft;
> > +
> > +	convert_to_efi_time(tm, &eft);
> > +
> > +	lock_kernel();
> > +
> > +	spin_lock_irqsave(&p->lock, flags);
> > +	status = efi.set_time(&eft);
> > +	spin_unlock_irqrestore(&p->lock, flags);
> > +
> > +	unlock_kernel();
> > +
> > +	return status == EFI_SUCCESS ? 0 : -EINVAL;
> > +}
> > +
> > +static const struct rtc_class_ops efi_rtc_ops = {
> > +	.read_time = efi_read_time,
> > +	.set_time = efi_set_time,
> > +	.read_alarm = efi_read_alarm,
> > +	.set_alarm = efi_set_alarm,
> > +};
> > +
> > +static int __devinit efi_rtc_probe(struct platform_device *dev)
> > +{
> > +	struct efi_rtc *p;
> > +
> > +	p = kzalloc(sizeof (*p), GFP_KERNEL);
> > +	if (!p)
> > +		return -ENOMEM;
> > +
> > +	spin_lock_init(&p->lock);
> > +
> > +	p->rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
> > +					THIS_MODULE);
> > +	if (IS_ERR(p->rtc)) {
> > +		int err = PTR_ERR(p->rtc);
> > +		kfree(p);
> > +		return err;
> > +	}
> > +
> > +	platform_set_drvdata(dev, p);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __devexit efi_rtc_remove(struct platform_device *dev)
> > +{
> > +	struct efi_rtc *p = platform_get_drvdata(dev);
> > +
> > +	rtc_device_unregister(p->rtc);
> > +	kfree(p);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver efi_rtc_driver = {
> > +	.driver = {
> > +		.name = "rtc-efi",
> > +		.owner = THIS_MODULE,
> > +	},
> > +	.probe = efi_rtc_probe,
> > +	.remove = __devexit_p(efi_rtc_remove),
> > +};
> > +
> > +static int __init efi_rtc_init(void)
> > +{
> > +	return platform_driver_register(&efi_rtc_driver);
> 
>  you can probably use platform_driver_probe

done

> > +}
> > +
> > +static void __exit efi_rtc_exit(void)
> > +{
> > +	platform_driver_unregister(&efi_rtc_driver);
> > +}
> > +
> > +module_init(efi_rtc_init);
> > +module_exit(efi_rtc_exit);
> > +
> > +MODULE_AUTHOR("dann frazier <dannf@hp.com>");
> > +MODULE_LICENSE("GPL");
> > +MODULE_DESCRIPTION("EFI RTC driver");

Will follow up w/ new patch.

Patch

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index f0ebb34..9ed5ba0 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -20,6 +20,7 @@ 
 #include <linux/efi.h>
 #include <linux/timex.h>
 #include <linux/clocksource.h>
+#include <linux/platform_device.h>
 
 #include <asm/machvec.h>
 #include <asm/delay.h>
@@ -405,6 +406,23 @@  static struct irqaction timer_irqaction = {
 	.name =		"timer"
 };
 
+struct platform_device rtc_efi_dev = {
+	.name = "rtc-efi",
+	.id = -1,
+};
+
+static int __init rtc_init(void)
+{
+	int ret;
+	ret = platform_device_register(&rtc_efi_dev);
+	if (ret < 0)
+		printk(KERN_ERR "unable to register rtc device...\n");
+       
+	/* not necessarily an error */
+	return 0;
+}
+module_init(rtc_init);
+
 void __init
 time_init (void)
 {
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 165a818..37ce842 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -433,6 +433,16 @@  config RTC_DRV_DS1742
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds1742.
 
+config RTC_DRV_EFI
+	tristate "EFI RTC"
+	depends on IA64
+	help
+	  If you say yes here you will get support for the EFI
+	  Real Time Clock.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-efi.
+
 config RTC_DRV_STK17TA8
 	tristate "Simtek STK17TA8"
 	depends on RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6e79c91..29db401 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -34,6 +34,7 @@  obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
 obj-$(CONFIG_RTC_DRV_DS3234)	+= rtc-ds3234.o
+obj-$(CONFIG_RTC_DRV_EFI)	+= rtc-efi.o
 obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
new file mode 100644
index 0000000..2386da0
--- /dev/null
+++ b/drivers/rtc/rtc-efi.c
@@ -0,0 +1,294 @@ 
+/*
+ * rtc-efi: RTC Class Driver for EFI-based systems
+ *
+ * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
+ *
+ * Author: dann frazier <dannf@hp.com>
+ * Based on efirtc.c by Stephane Eranian
+ *
+ *  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.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/time.h>
+#include <linux/platform_device.h>
+
+#include <linux/efi.h>
+
+#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
+/*
+ * EFI Epoch is 1/1/1998
+ */
+#define EFI_RTC_EPOCH		1998
+
+#define is_leap(year) \
+	((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
+
+struct efi_rtc {
+	struct rtc_device *rtc;
+	spinlock_t lock;
+};
+
+static const unsigned short int __mon_yday[2][13] =
+{
+	/* Normal years.  */
+	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
+	/* Leap years.  */
+	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
+};
+
+/*
+ * returns day of the year [0-365]
+ */
+static inline int
+compute_yday(efi_time_t *eft)
+{
+	/* efi_time_t.month is in the [1-12] so, we need -1 */
+	return  __mon_yday[is_leap(eft->year)][eft->month-1] + eft->day - 1;
+}
+/*
+ * returns day of the week [0-6] 0=Sunday
+ *
+ * Don't try to provide a year that's before 1998, please !
+ */
+static int
+compute_wday(efi_time_t *eft)
+{
+	int y;
+	int ndays = 0;
+
+	if (eft->year < 1998) {
+		printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
+		return -1;
+	}
+
+	for (y = EFI_RTC_EPOCH; y < eft->year; y++)
+		ndays += 365 + (is_leap(y) ? 1 : 0);
+
+	ndays += compute_yday(eft);
+
+	/*
+	 * 4=1/1/1998 was a Thursday
+	 */
+	return (ndays + 4) % 7;
+}
+
+static void
+convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
+{
+
+	eft->year	= wtime->tm_year + 1900;
+	eft->month	= wtime->tm_mon + 1;
+	eft->day	= wtime->tm_mday;
+	eft->hour	= wtime->tm_hour;
+	eft->minute	= wtime->tm_min;
+	eft->second 	= wtime->tm_sec;
+	eft->nanosecond = 0;
+	eft->daylight	= wtime->tm_isdst ? EFI_ISDST : 0;
+	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
+}
+
+static void
+convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
+{
+	memset(wtime, 0, sizeof(*wtime));
+	wtime->tm_sec  = eft->second;
+	wtime->tm_min  = eft->minute;
+	wtime->tm_hour = eft->hour;
+	wtime->tm_mday = eft->day;
+	wtime->tm_mon  = eft->month - 1;
+	wtime->tm_year = eft->year - 1900;
+
+	/* day of the week [0-6], Sunday=0 */
+	wtime->tm_wday = compute_wday(eft);
+
+	/* day in the year [1-365]*/
+	wtime->tm_yday = compute_yday(eft);
+
+
+	switch (eft->daylight & EFI_ISDST) {
+	case EFI_ISDST:
+		wtime->tm_isdst = 1;
+		break;
+	case EFI_TIME_ADJUST_DAYLIGHT:
+		wtime->tm_isdst = 0;
+		break;
+	default:
+		wtime->tm_isdst = -1;
+	}
+}
+
+static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct efi_rtc *p = dev_get_drvdata(dev);
+	efi_time_t eft;
+	efi_status_t status;
+	unsigned long flags;
+
+	lock_kernel();
+
+	spin_lock_irqsave(&p->lock, flags);
+	/*
+	 * As of EFI v1.10, this call always returns an unsupported status
+	 */
+	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
+				     (efi_bool_t *)&wkalrm->pending, &eft);
+	spin_unlock_irqrestore(&p->lock, flags);
+
+	unlock_kernel();
+
+	if (status != EFI_SUCCESS)
+		return -EINVAL;
+
+	convert_from_efi_time(&eft, &wkalrm->time);
+
+	return 0;
+}
+
+static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct efi_rtc *p = dev_get_drvdata(dev);
+	efi_time_t eft;
+	efi_status_t status;
+	unsigned long flags;
+
+	convert_to_efi_time(&wkalrm->time, &eft);
+
+	lock_kernel();
+
+	spin_lock_irqsave(&p->lock, flags);
+	/*
+	 * XXX Fixme:
+	 * As of EFI 0.92 with the firmware I have on my
+	 * machine this call does not seem to work quite
+	 * right
+	 *
+	 * As of v1.10, this call always returns an unsupported status
+	 */
+	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
+	spin_unlock_irqrestore(&p->lock, flags);
+
+	unlock_kernel();
+
+	printk(KERN_WARNING "write status is %d\n", (int)status);
+
+	return status == EFI_SUCCESS ? 0 : -EINVAL;
+}
+
+static int efi_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct efi_rtc *p = dev_get_drvdata(dev);
+	unsigned long flags;
+	efi_status_t status;
+	efi_time_t eft;
+	efi_time_cap_t cap;
+
+	lock_kernel();
+
+	spin_lock_irqsave(&p->lock, flags);
+	status = efi.get_time(&eft, &cap);
+	spin_unlock_irqrestore(&p->lock, flags);
+
+	unlock_kernel();
+
+	if (status != EFI_SUCCESS) {
+		/* should never happen */
+		printk(KERN_ERR "efitime: can't read time\n");
+		return -EINVAL;
+	}
+
+	convert_from_efi_time(&eft, tm);
+
+	return 0;
+}
+
+static int efi_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct efi_rtc *p = dev_get_drvdata(dev);
+	unsigned long flags;
+	efi_status_t status;
+	efi_time_t eft;
+
+	convert_to_efi_time(tm, &eft);
+
+	lock_kernel();
+
+	spin_lock_irqsave(&p->lock, flags);
+	status = efi.set_time(&eft);
+	spin_unlock_irqrestore(&p->lock, flags);
+
+	unlock_kernel();
+
+	return status == EFI_SUCCESS ? 0 : -EINVAL;
+}
+
+static const struct rtc_class_ops efi_rtc_ops = {
+	.read_time = efi_read_time,
+	.set_time = efi_set_time,
+	.read_alarm = efi_read_alarm,
+	.set_alarm = efi_set_alarm,
+};
+
+static int __devinit efi_rtc_probe(struct platform_device *dev)
+{
+	struct efi_rtc *p;
+
+	p = kzalloc(sizeof (*p), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	spin_lock_init(&p->lock);
+
+	p->rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
+					THIS_MODULE);
+	if (IS_ERR(p->rtc)) {
+		int err = PTR_ERR(p->rtc);
+		kfree(p);
+		return err;
+	}
+
+	platform_set_drvdata(dev, p);
+
+	return 0;
+}
+
+static int __devexit efi_rtc_remove(struct platform_device *dev)
+{
+	struct efi_rtc *p = platform_get_drvdata(dev);
+
+	rtc_device_unregister(p->rtc);
+	kfree(p);
+
+	return 0;
+}
+
+static struct platform_driver efi_rtc_driver = {
+	.driver = {
+		.name = "rtc-efi",
+		.owner = THIS_MODULE,
+	},
+	.probe = efi_rtc_probe,
+	.remove = __devexit_p(efi_rtc_remove),
+};
+
+static int __init efi_rtc_init(void)
+{
+	return platform_driver_register(&efi_rtc_driver);
+}
+
+static void __exit efi_rtc_exit(void)
+{
+	platform_driver_unregister(&efi_rtc_driver);
+}
+
+module_init(efi_rtc_init);
+module_exit(efi_rtc_exit);
+
+MODULE_AUTHOR("dann frazier <dannf@hp.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("EFI RTC driver");