diff mbox

rtc: Add stand-alone driver for RX8025 chip

Message ID 20090420215602.13835.57707.stgit@i1501.lan.towertech.it
State Accepted, archived
Headers show

Commit Message

Alessandro Zummo April 20, 2009, 9:56 p.m. UTC
From: Wolfgang Grandegger <wg@grandegger.com>

This patch adds support for the Epson RX-8025SA/NB RTC chips. It
includes support for alarms, periodic interrupts (1 Hz) and clock
precision adjustment.

For clock precision adjustment, the SYSFS file "clock_adjust_ppb" gets
created in "/sys/class/rtc/rtcX/device". It permits to set and get the
clock adjustment in ppb (parts per billion), e.g.:

  # echo -183000 > /sys/class/rtc/rtc0/device/clock_adjust_ppb
  # cat /sys/class/rtc/rtc0/device/clock_adjust_ppb
  -183000

This allows to compensate temperature dependent clock drifts. According
to the RX8025 SA/NB application manual the frequency and temperature
characteristics can be approximated using the following equation:

  df = a * (ut - t)**2

  df: Frequency deviation in any temperature
  a : Coefficient = (-35 +-5) * 10**-9
  ut: Ultimate temperature in degree = +25 +-5 degree
  t : Any temperature in degree


Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Sergei Poselenov <sposelenov@emcraft.com>
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Dmitry Rakhchev <rda@emcraft.com>
Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
---

 drivers/rtc/Kconfig      |    9 +
 drivers/rtc/Makefile     |    1 
 drivers/rtc/rtc-rx8025.c |  688 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 698 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-rx8025.c



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Comments

Andrew Morton April 20, 2009, 10:22 p.m. UTC | #1
On Mon, 20 Apr 2009 23:56:02 +0200
Alessandro Zummo <a.zummo@towertech.it> wrote:

> From: Wolfgang Grandegger <wg@grandegger.com>
> 
> This patch adds support for the Epson RX-8025SA/NB RTC chips. It
> includes support for alarms, periodic interrupts (1 Hz) and clock
> precision adjustment.
> 
> For clock precision adjustment, the SYSFS file "clock_adjust_ppb" gets
> created in "/sys/class/rtc/rtcX/device". It permits to set and get the
> clock adjustment in ppb (parts per billion), e.g.:
> 
>   # echo -183000 > /sys/class/rtc/rtc0/device/clock_adjust_ppb
>   # cat /sys/class/rtc/rtc0/device/clock_adjust_ppb
>   -183000
> 
> This allows to compensate temperature dependent clock drifts. According
> to the RX8025 SA/NB application manual the frequency and temperature
> characteristics can be approximated using the following equation:
> 
>   df = a * (ut - t)**2
> 
>   df: Frequency deviation in any temperature
>   a : Coefficient = (-35 +-5) * 10**-9
>   ut: Ultimate temperature in degree = +25 +-5 degree
>   t : Any temperature in degree

clock_adjust_ppb sounds like something which other hardware devices
could use.  Is it appropriate that it was wholly implemented within one
particular driver?

>
> ...
>
> --- /dev/null
> +++ b/drivers/rtc/rtc-rx8025.c
> @@ -0,0 +1,688 @@
> +/*
> + * Driver for Epson's RTC module RX-8025 SA/NB
> + *
> + * Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
> + *
> + * Copyright (C) 2005 by Digi International Inc.
> + * All rights reserved.
> + *
> + * Modify by fengjh at rising.com.cn

"modified by"

> + * <http://lists.lm-sensors.org/mailman/listinfo/lm-sensors>
> + * 2006.11
> + *
> + * Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
> + * Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
> + * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * version 2 as published by the Free Software Foundation.
> + */
>
> ...
>
> +static void rx8025_work(struct work_struct *work)
> +{
> +	struct rx8025_data *rx8025 = container_of(work, struct rx8025_data,
> +						  work);
> +	struct i2c_client *client = rx8025->client;
> +	struct mutex *lock = &rx8025->rtc->ops_lock;
> +	u8 status;
> +
> +	mutex_lock(lock);
> +
> +	if (rx8025_read_reg(client, RX8025_REG_CTRL2, &status))
> +		goto out;
> +
> +	if (!(status & RX8025_BIT_CTRL2_XST))
> +		dev_warn(&client->dev, "Oscillation stop was detected,"
> +			 "you may have to readjust the clock\n");
> +
> +	if (status & RX8025_BIT_CTRL2_CTFG) {
> +		/* periodic */
> +		status &= ~RX8025_BIT_CTRL2_CTFG;
> +		local_irq_disable();
> +		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
> +		local_irq_enable();

Please remind me again why it is necessary to disable interrupts on
this CPU, but it is not necessary to disable them on other CPUs, or to
take some lock or something.

I've asked this before, but I always forget.  It's odd.

> +	}
> +
> +	if (status & RX8025_BIT_CTRL2_DAFG) {
> +		/* alarm */
> +		status &= RX8025_BIT_CTRL2_DAFG;
> +		if (rx8025_write_reg(client, RX8025_REG_CTRL1,
> +				     rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
> +			goto out;
> +		local_irq_disable();
> +		rtc_update_irq(rx8025->rtc, 1, RTC_AF | RTC_IRQF);
> +		local_irq_enable();
> +	}
> +
> +	/* acknowledge IRQ */
> +	rx8025_write_reg(client, RX8025_REG_CTRL2,
> +			 status | RX8025_BIT_CTRL2_XST);
> +
> +out:
> +	if (!rx8025->exiting)
> +		enable_irq(client->irq);
> +
> +	mutex_unlock(lock);
> +}
> +
>
> ...
>
> +static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
> +					       struct device_attribute *attr,
> +					       const char *buf, size_t count)
> +{
> +	int adj, err;
> +
> +	if (sscanf(buf, "%i", &adj) != 1)
> +		return -EINVAL;

This will permit user input of the form "42foo", which is sloppy. 
strict_strtoul() and friends were added to solve this.


> +	err = rx8025_set_clock_adjust(dev, adj);
> +
> +	return err ? err : count;
> +}
> +
>
> ...
>


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Alessandro Zummo April 21, 2009, 12:05 a.m. UTC | #2
On Mon, 20 Apr 2009 15:22:04 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:


> 
> clock_adjust_ppb sounds like something which other hardware devices
> could use.  Is it appropriate that it was wholly implemented within one
> particular driver?

 This is the first driver for a chip with hardware compensation
 support. It might be generalized at some point.


> > +	if (status & RX8025_BIT_CTRL2_CTFG) {
> > +		/* periodic */
> > +		status &= ~RX8025_BIT_CTRL2_CTFG;
> > +		local_irq_disable();
> > +		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
> > +		local_irq_enable();
> 
> Please remind me again why it is necessary to disable interrupts on
> this CPU, but it is not necessary to disable them on other CPUs, or to
> take some lock or something.
> 
> I've asked this before, but I always forget.  It's odd.

 I believe we are carrying around a legacy of some kind. It shouldn't
 be necessary.

 rtc_update_irq seems doing a fine job with locking.
Alessandro Zummo April 21, 2009, 12:41 a.m. UTC | #3
On Mon, 20 Apr 2009 15:22:04 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> > +		local_irq_disable();
> > +		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
> > +		local_irq_enable();  
> 
> Please remind me again why it is necessary to disable interrupts on
> this CPU, but it is not necessary to disable them on other CPUs, or to
> take some lock or something.
> 
> I've asked this before, but I always forget.  It's odd.

 I gave a quick look to the matter. We have two locks
 involved. irq_lock and irq_task_lock.

 The second one should not taken by drivers (there's at least
 one that does and it should be addressed).

 The first one is usually taken by drivers when they need
 to setup alarms and similar.

 Now, if those rarely called operations are executed within
 spin_lock_irq/spin_unlock_irq, it shouldn't be necessary to
 disable irqs when calling rtc_update_irq.

 Am I right? It's late here so I may have got the whole
 thing wrong...
Mark Brown April 21, 2009, 9:47 a.m. UTC | #4
On Tue, Apr 21, 2009 at 02:05:59AM +0200, Alessandro Zummo wrote:
> Andrew Morton <akpm@linux-foundation.org> wrote:

> > clock_adjust_ppb sounds like something which other hardware devices
> > could use.  Is it appropriate that it was wholly implemented within one
> > particular driver?

>  This is the first driver for a chip with hardware compensation
>  support. It might be generalized at some point.

I'd expect that there are existing drivers would be able to use such a
feature - the wm835x has a frequency trim feature, for example.

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Andrew Morton April 21, 2009, 9:56 p.m. UTC | #5
On Mon, 20 Apr 2009 23:56:02 +0200
Alessandro Zummo <a.zummo@towertech.it> wrote:

> This patch adds support for the Epson RX-8025SA/NB RTC chips. It
> includes support for alarms, periodic interrupts (1 Hz) and clock
> precision adjustment.

drivers/rtc/rtc-rx8025.c: In function 'rx8025_read_alarm':
drivers/rtc/rtc-rx8025.c:324: error: 'NO_IRQ' undeclared (first use in this function)
drivers/rtc/rtc-rx8025.c:324: error: (Each undeclared identifier is reported only once
drivers/rtc/rtc-rx8025.c:324: error: for each function it appears in.)

perhaps this thing is specific to some particular architecture?


This happens again and again.  We should just go and delete NO_IRQ from
the kernel or something.  Look at this stupidity:


drivers/input/touchscreen/ucb1400_ts.c:
#ifndef NO_IRQ
#define NO_IRQ  0
#endif

drivers/pcmcia/pd6729.c:
#ifndef NO_IRQ
#define NO_IRQ  ((unsigned int)(0))
#endif

drivers/rtc/rtc-m48t59.c:
#ifndef NO_IRQ
#define NO_IRQ  (-1)
#endif

drivers/scsi/arm/fas216.h:
#ifndef NO_IRQ
#define NO_IRQ 255
#endif

wtf?

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Wolfgang Grandegger April 22, 2009, 7:01 a.m. UTC | #6
Andrew Morton wrote:
> On Mon, 20 Apr 2009 23:56:02 +0200
> Alessandro Zummo <a.zummo@towertech.it> wrote:
> 
>> This patch adds support for the Epson RX-8025SA/NB RTC chips. It
>> includes support for alarms, periodic interrupts (1 Hz) and clock
>> precision adjustment.
> 
> drivers/rtc/rtc-rx8025.c: In function 'rx8025_read_alarm':
> drivers/rtc/rtc-rx8025.c:324: error: 'NO_IRQ' undeclared (first use in this function)
> drivers/rtc/rtc-rx8025.c:324: error: (Each undeclared identifier is reported only once
> drivers/rtc/rtc-rx8025.c:324: error: for each function it appears in.)
> 
> perhaps this thing is specific to some particular architecture?

PowerPC and ARM seem to use it, at least.

> 
> This happens again and again.  We should just go and delete NO_IRQ from
> the kernel or something.  Look at this stupidity:
> 
> 
> drivers/input/touchscreen/ucb1400_ts.c:
> #ifndef NO_IRQ
> #define NO_IRQ  0
> #endif
> 
> drivers/pcmcia/pd6729.c:
> #ifndef NO_IRQ
> #define NO_IRQ  ((unsigned int)(0))
> #endif
> 
> drivers/rtc/rtc-m48t59.c:
> #ifndef NO_IRQ
> #define NO_IRQ  (-1)
> #endif
> 
> drivers/scsi/arm/fas216.h:
> #ifndef NO_IRQ
> #define NO_IRQ 255
> #endif
> 
> wtf?

Right, and therefore I removed similar lines from rtc-rx8025.c assuming
that every arch has it already defined... and if not, I regard it as
mistake. Obviously, that's not the case. I think the generic IRQ layer
should define a proper default value but I might be too naive. I found
the following related thread:

  http://lkml.org/lkml/2008/6/22/301

Wolfgang.


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Andrew Morton April 22, 2009, 7:17 a.m. UTC | #7
On Wed, 22 Apr 2009 09:01:54 +0200 Wolfgang Grandegger <wg@grandegger.com> wrote:

> Andrew Morton wrote:
> > On Mon, 20 Apr 2009 23:56:02 +0200
> > Alessandro Zummo <a.zummo@towertech.it> wrote:
> > 
> >> This patch adds support for the Epson RX-8025SA/NB RTC chips. It
> >> includes support for alarms, periodic interrupts (1 Hz) and clock
> >> precision adjustment.
> > 
> > drivers/rtc/rtc-rx8025.c: In function 'rx8025_read_alarm':
> > drivers/rtc/rtc-rx8025.c:324: error: 'NO_IRQ' undeclared (first use in this function)
> > drivers/rtc/rtc-rx8025.c:324: error: (Each undeclared identifier is reported only once
> > drivers/rtc/rtc-rx8025.c:324: error: for each function it appears in.)
> > 
> > perhaps this thing is specific to some particular architecture?
> 
> PowerPC and ARM seem to use it, at least.

Seem to use what?  "RX-8025SA/NB RTC chips" or NO_IRQ?

If the former then an appropriate fix would be to add the necessary
Kconfig dependencies.

But if we want this driver to compile on other architectures then
NO_IRQ needs to go away.  Other rtc drivers do

	if (client->irq <= 0)

which covers both the standard convention (irq 0 is disallowed) as well
as the arm/ppc/etc peculiarity.


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Wolfgang Grandegger April 22, 2009, 7:34 a.m. UTC | #8
Andrew Morton wrote:
> On Wed, 22 Apr 2009 09:01:54 +0200 Wolfgang Grandegger <wg@grandegger.com> wrote:
> 
>> Andrew Morton wrote:
>>> On Mon, 20 Apr 2009 23:56:02 +0200
>>> Alessandro Zummo <a.zummo@towertech.it> wrote:
>>>
>>>> This patch adds support for the Epson RX-8025SA/NB RTC chips. It
>>>> includes support for alarms, periodic interrupts (1 Hz) and clock
>>>> precision adjustment.
>>> drivers/rtc/rtc-rx8025.c: In function 'rx8025_read_alarm':
>>> drivers/rtc/rtc-rx8025.c:324: error: 'NO_IRQ' undeclared (first use in this function)
>>> drivers/rtc/rtc-rx8025.c:324: error: (Each undeclared identifier is reported only once
>>> drivers/rtc/rtc-rx8025.c:324: error: for each function it appears in.)
>>>
>>> perhaps this thing is specific to some particular architecture?
>> PowerPC and ARM seem to use it, at least.
> 
> Seem to use what?  "RX-8025SA/NB RTC chips" or NO_IRQ?

Seem to define NO_IRQ. PowerPC sets it to 0 and ARM still to -1.

> If the former then an appropriate fix would be to add the necessary
> Kconfig dependencies.
> 
> But if we want this driver to compile on other architectures then
> NO_IRQ needs to go away.  Other rtc drivers do
> 
> 	if (client->irq <= 0)
> 
> which covers both the standard convention (irq 0 is disallowed) as well
> as the arm/ppc/etc peculiarity.

OK, should I send a revised patch? Alessandro?

Wolfgang.


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Andrew Morton April 22, 2009, 7:40 a.m. UTC | #9
On Wed, 22 Apr 2009 09:34:50 +0200 Wolfgang Grandegger <wg@grandegger.com> wrote:

> > If the former then an appropriate fix would be to add the necessary
> > Kconfig dependencies.
> > 
> > But if we want this driver to compile on other architectures then
> > NO_IRQ needs to go away.  Other rtc drivers do
> > 
> > 	if (client->irq <= 0)
> > 
> > which covers both the standard convention (irq 0 is disallowed) as well
> > as the arm/ppc/etc peculiarity.
> 
> OK, should I send a revised patch?

yes please.

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diff mbox

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ffe34a1..1cf1ae9 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -296,6 +296,15 @@  config RTC_DRV_RX8581
 	  This driver can also be built as a module. If so the module
 	  will be called rtc-rx8581.
 
+config RTC_DRV_RX8025
+	tristate "Epson RX-8025SA/NB"
+	help
+	  If you say yes here you get support for the Epson
+	  RX-8025SA/NB RTC chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-rx8025.
+
 endif # I2C
 
 comment "SPI RTC drivers"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6c0639a..3c0f2b2 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -62,6 +62,7 @@  obj-$(CONFIG_RTC_DRV_R9701)	+= rtc-r9701.o
 obj-$(CONFIG_RTC_DRV_RS5C313)	+= rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_RS5C348)	+= rtc-rs5c348.o
 obj-$(CONFIG_RTC_DRV_RS5C372)	+= rtc-rs5c372.o
+obj-$(CONFIG_RTC_DRV_RX8025)	+= rtc-rx8025.o
 obj-$(CONFIG_RTC_DRV_RX8581)	+= rtc-rx8581.o
 obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
diff --git a/drivers/rtc/rtc-rx8025.c b/drivers/rtc/rtc-rx8025.c
new file mode 100644
index 0000000..98d7fbc
--- /dev/null
+++ b/drivers/rtc/rtc-rx8025.c
@@ -0,0 +1,688 @@ 
+/*
+ * Driver for Epson's RTC module RX-8025 SA/NB
+ *
+ * Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
+ *
+ * Copyright (C) 2005 by Digi International Inc.
+ * All rights reserved.
+ *
+ * Modify by fengjh at rising.com.cn
+ * <http://lists.lm-sensors.org/mailman/listinfo/lm-sensors>
+ * 2006.11
+ *
+ * Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
+ * Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
+ * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/bcd.h>
+#include <linux/i2c.h>
+#include <linux/list.h>
+#include <linux/rtc.h>
+
+/* Register definitions */
+#define RX8025_REG_SEC		0x00
+#define RX8025_REG_MIN		0x01
+#define RX8025_REG_HOUR		0x02
+#define RX8025_REG_WDAY		0x03
+#define RX8025_REG_MDAY		0x04
+#define RX8025_REG_MONTH	0x05
+#define RX8025_REG_YEAR		0x06
+#define RX8025_REG_DIGOFF	0x07
+#define RX8025_REG_ALWMIN	0x08
+#define RX8025_REG_ALWHOUR	0x09
+#define RX8025_REG_ALWWDAY	0x0a
+#define RX8025_REG_ALDMIN	0x0b
+#define RX8025_REG_ALDHOUR	0x0c
+/* 0x0d is reserved */
+#define RX8025_REG_CTRL1	0x0e
+#define RX8025_REG_CTRL2	0x0f
+
+#define RX8025_BIT_CTRL1_CT	(7 << 0)
+/* 1 Hz periodic level irq */
+#define RX8025_BIT_CTRL1_CT_1HZ	4
+#define RX8025_BIT_CTRL1_TEST	(1 << 3)
+#define RX8025_BIT_CTRL1_1224	(1 << 5)
+#define RX8025_BIT_CTRL1_DALE	(1 << 6)
+#define RX8025_BIT_CTRL1_WALE	(1 << 7)
+
+#define RX8025_BIT_CTRL2_DAFG	(1 << 0)
+#define RX8025_BIT_CTRL2_WAFG	(1 << 1)
+#define RX8025_BIT_CTRL2_CTFG	(1 << 2)
+#define RX8025_BIT_CTRL2_PON	(1 << 4)
+#define RX8025_BIT_CTRL2_XST	(1 << 5)
+#define RX8025_BIT_CTRL2_VDET	(1 << 6)
+
+/* Clock precision adjustment */
+#define RX8025_ADJ_RESOLUTION	3050 /* in ppb */
+#define RX8025_ADJ_DATA_MAX	62
+#define RX8025_ADJ_DATA_MIN	-62
+
+static const struct i2c_device_id rx8025_id[] = {
+	{ "rx8025", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, rx8025_id);
+
+struct rx8025_data {
+	struct i2c_client *client;
+	struct rtc_device *rtc;
+	struct work_struct work;
+	u8 ctrl1;
+	unsigned exiting:1;
+};
+
+static int rx8025_read_reg(struct i2c_client *client, int number, u8 *value)
+{
+	int ret = i2c_smbus_read_byte_data(client, (number << 4) | 0x08);
+
+	if (ret < 0) {
+		dev_err(&client->dev, "Unable to read register #%d\n", number);
+		return ret;
+	}
+
+	*value = ret;
+	return 0;
+}
+
+static int rx8025_read_regs(struct i2c_client *client,
+			    int number, u8 length, u8 *values)
+{
+	int ret = i2c_smbus_read_i2c_block_data(client, (number << 4) | 0x08,
+						length, values);
+
+	if (ret != length) {
+		dev_err(&client->dev, "Unable to read registers #%d..#%d\n",
+			number, number + length - 1);
+		return ret < 0 ? ret : -EIO;
+	}
+
+	return 0;
+}
+
+static int rx8025_write_reg(struct i2c_client *client, int number, u8 value)
+{
+	int ret = i2c_smbus_write_byte_data(client, number << 4, value);
+
+	if (ret)
+		dev_err(&client->dev, "Unable to write register #%d\n",
+			number);
+
+	return ret;
+}
+
+static int rx8025_write_regs(struct i2c_client *client,
+			     int number, u8 length, u8 *values)
+{
+	int ret = i2c_smbus_write_i2c_block_data(client, (number << 4) | 0x08,
+						 length, values);
+
+	if (ret)
+		dev_err(&client->dev, "Unable to write registers #%d..#%d\n",
+			number, number + length - 1);
+
+	return ret;
+}
+
+static irqreturn_t rx8025_irq(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
+
+	disable_irq_nosync(irq);
+	schedule_work(&rx8025->work);
+	return IRQ_HANDLED;
+}
+
+static void rx8025_work(struct work_struct *work)
+{
+	struct rx8025_data *rx8025 = container_of(work, struct rx8025_data,
+						  work);
+	struct i2c_client *client = rx8025->client;
+	struct mutex *lock = &rx8025->rtc->ops_lock;
+	u8 status;
+
+	mutex_lock(lock);
+
+	if (rx8025_read_reg(client, RX8025_REG_CTRL2, &status))
+		goto out;
+
+	if (!(status & RX8025_BIT_CTRL2_XST))
+		dev_warn(&client->dev, "Oscillation stop was detected,"
+			 "you may have to readjust the clock\n");
+
+	if (status & RX8025_BIT_CTRL2_CTFG) {
+		/* periodic */
+		status &= ~RX8025_BIT_CTRL2_CTFG;
+		local_irq_disable();
+		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
+		local_irq_enable();
+	}
+
+	if (status & RX8025_BIT_CTRL2_DAFG) {
+		/* alarm */
+		status &= RX8025_BIT_CTRL2_DAFG;
+		if (rx8025_write_reg(client, RX8025_REG_CTRL1,
+				     rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
+			goto out;
+		local_irq_disable();
+		rtc_update_irq(rx8025->rtc, 1, RTC_AF | RTC_IRQF);
+		local_irq_enable();
+	}
+
+	/* acknowledge IRQ */
+	rx8025_write_reg(client, RX8025_REG_CTRL2,
+			 status | RX8025_BIT_CTRL2_XST);
+
+out:
+	if (!rx8025->exiting)
+		enable_irq(client->irq);
+
+	mutex_unlock(lock);
+}
+
+static int rx8025_get_time(struct device *dev, struct rtc_time *dt)
+{
+	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
+	u8 date[7];
+	int err;
+
+	err = rx8025_read_regs(rx8025->client, RX8025_REG_SEC, 7, date);
+	if (err)
+		return err;
+
+	dev_dbg(dev, "%s: read 0x%02x 0x%02x "
+		"0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n", __func__,
+		date[0], date[1], date[2], date[3], date[4],
+		date[5], date[6]);
+
+	dt->tm_sec = bcd2bin(date[RX8025_REG_SEC] & 0x7f);
+	dt->tm_min = bcd2bin(date[RX8025_REG_MIN] & 0x7f);
+	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
+		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x3f);
+	else
+		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x1f) % 12
+			+ (date[RX8025_REG_HOUR] & 0x20 ? 12 : 0);
+
+	dt->tm_mday = bcd2bin(date[RX8025_REG_MDAY] & 0x3f);
+	dt->tm_mon = bcd2bin(date[RX8025_REG_MONTH] & 0x1f) - 1;
+	dt->tm_year = bcd2bin(date[RX8025_REG_YEAR]);
+
+	if (dt->tm_year < 70)
+		dt->tm_year += 100;
+
+	dev_dbg(dev, "%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
+		dt->tm_sec, dt->tm_min, dt->tm_hour,
+		dt->tm_mday, dt->tm_mon, dt->tm_year);
+
+	return rtc_valid_tm(dt);
+}
+
+static int rx8025_set_time(struct device *dev, struct rtc_time *dt)
+{
+	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
+	u8 date[7];
+
+	/*
+	 * BUG: The HW assumes every year that is a multiple of 4 to be a leap
+	 * year.  Next time this is wrong is 2100, which will not be a leap
+	 * year.
+	 */
+
+	/*
+	 * Here the read-only bits are written as "0".  I'm not sure if that
+	 * is sound.
+	 */
+	date[RX8025_REG_SEC] = bin2bcd(dt->tm_sec);
+	date[RX8025_REG_MIN] = bin2bcd(dt->tm_min);
+	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
+		date[RX8025_REG_HOUR] = bin2bcd(dt->tm_hour);
+	else
+		date[RX8025_REG_HOUR] = (dt->tm_hour >= 12 ? 0x20 : 0)
+			| bin2bcd((dt->tm_hour + 11) % 12 + 1);
+
+	date[RX8025_REG_WDAY] = bin2bcd(dt->tm_wday);
+	date[RX8025_REG_MDAY] = bin2bcd(dt->tm_mday);
+	date[RX8025_REG_MONTH] = bin2bcd(dt->tm_mon + 1);
+	date[RX8025_REG_YEAR] = bin2bcd(dt->tm_year % 100);
+
+	dev_dbg(dev,
+		"%s: write 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n",
+		__func__,
+		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
+
+	return rx8025_write_regs(rx8025->client, RX8025_REG_SEC, 7, date);
+}
+
+static int rx8025_init_client(struct i2c_client *client, int *need_reset)
+{
+	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
+	u8 ctrl[2], ctrl2;
+	int need_clear = 0;
+	int err;
+
+	err = rx8025_read_regs(rx8025->client, RX8025_REG_CTRL1, 2, ctrl);
+	if (err)
+		goto out;
+
+	/* Keep test bit zero ! */
+	rx8025->ctrl1 = ctrl[0] & ~RX8025_BIT_CTRL1_TEST;
+
+	if (ctrl[1] & RX8025_BIT_CTRL2_PON) {
+		dev_warn(&client->dev, "power-on reset was detected, "
+			 "you may have to readjust the clock\n");
+		*need_reset = 1;
+	}
+
+	if (ctrl[1] & RX8025_BIT_CTRL2_VDET) {
+		dev_warn(&client->dev, "a power voltage drop was detected, "
+			 "you may have to readjust the clock\n");
+		*need_reset = 1;
+	}
+
+	if (!(ctrl[1] & RX8025_BIT_CTRL2_XST)) {
+		dev_warn(&client->dev, "Oscillation stop was detected,"
+			 "you may have to readjust the clock\n");
+		*need_reset = 1;
+	}
+
+	if (ctrl[1] & (RX8025_BIT_CTRL2_DAFG | RX8025_BIT_CTRL2_WAFG)) {
+		dev_warn(&client->dev, "Alarm was detected\n");
+		need_clear = 1;
+	}
+
+	if (!(ctrl[1] & RX8025_BIT_CTRL2_CTFG))
+		need_clear = 1;
+
+	if (*need_reset || need_clear) {
+		ctrl2 = ctrl[0];
+		ctrl2 &= ~(RX8025_BIT_CTRL2_PON | RX8025_BIT_CTRL2_VDET |
+			   RX8025_BIT_CTRL2_CTFG | RX8025_BIT_CTRL2_WAFG |
+			   RX8025_BIT_CTRL2_DAFG);
+		ctrl2 |= RX8025_BIT_CTRL2_XST;
+
+		err = rx8025_write_reg(client, RX8025_REG_CTRL2, ctrl2);
+	}
+out:
+	return err;
+}
+
+/* Alarm support */
+static int rx8025_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
+	struct i2c_client *client = rx8025->client;
+	u8 ctrl2, ald[2];
+	int err;
+
+	if (client->irq == NO_IRQ)
+		return -EINVAL;
+
+	err = rx8025_read_regs(client, RX8025_REG_ALDMIN, 2, ald);
+	if (err)
+		return err;
+
+	err = rx8025_read_reg(client, RX8025_REG_CTRL2, &ctrl2);
+	if (err)
+		return err;
+
+	dev_dbg(dev, "%s: read alarm 0x%02x 0x%02x ctrl2 %02x\n",
+		__func__, ald[0], ald[1], ctrl2);
+
+	/* Hardware alarms precision is 1 minute! */
+	t->time.tm_sec = 0;
+	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
+	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
+		t->time.tm_hour = bcd2bin(ald[1] & 0x3f);
+	else
+		t->time.tm_hour = bcd2bin(ald[1] & 0x1f) % 12
+			+ (ald[1] & 0x20 ? 12 : 0);
+
+	t->time.tm_wday = -1;
+	t->time.tm_mday = -1;
+	t->time.tm_mon = -1;
+	t->time.tm_year = -1;
+
+	dev_dbg(dev, "%s: date: %ds %dm %dh %dmd %dm %dy\n",
+		__func__,
+		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
+		t->time.tm_mday, t->time.tm_mon, t->time.tm_year);
+	t->enabled = !!(rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE);
+	t->pending = (ctrl2 & RX8025_BIT_CTRL2_DAFG) && t->enabled;
+
+	return err;
+}
+
+static int rx8025_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
+	u8 ald[2];
+	int err;
+
+	if (client->irq == NO_IRQ)
+		return -EINVAL;
+
+	/* Hardware alarm precision is 1 minute! */
+	ald[0] = bin2bcd(t->time.tm_min);
+	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
+		ald[1] = bin2bcd(t->time.tm_hour);
+	else
+		ald[1] = (t->time.tm_hour >= 12 ? 0x20 : 0)
+			| bin2bcd((t->time.tm_hour + 11) % 12 + 1);
+
+	dev_dbg(dev, "%s: write 0x%02x 0x%02x\n", __func__, ald[0], ald[1]);
+
+	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE) {
+		rx8025->ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
+		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
+				       rx8025->ctrl1);
+		if (err)
+			return err;
+	}
+	err = rx8025_write_regs(rx8025->client, RX8025_REG_ALDMIN, 2, ald);
+	if (err)
+		return err;
+
+	if (t->enabled) {
+		rx8025->ctrl1 |= RX8025_BIT_CTRL1_DALE;
+		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
+				       rx8025->ctrl1);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int rx8025_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
+	u8 ctrl1;
+	int err;
+
+	ctrl1 = rx8025->ctrl1;
+	if (enabled)
+		ctrl1 |= RX8025_BIT_CTRL1_DALE;
+	else
+		ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
+
+	if (ctrl1 != rx8025->ctrl1) {
+		rx8025->ctrl1 = ctrl1;
+		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
+				       rx8025->ctrl1);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int rx8025_irq_set_state(struct device *dev, int enabled)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
+	int ctrl1;
+	int err;
+
+	if (client->irq == NO_IRQ)
+		return -ENXIO;
+
+	ctrl1 = rx8025->ctrl1 & ~RX8025_BIT_CTRL1_CT;
+	if (enabled)
+		ctrl1 |= RX8025_BIT_CTRL1_CT_1HZ;
+	if (ctrl1 != rx8025->ctrl1) {
+		rx8025->ctrl1 = ctrl1;
+		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
+				       rx8025->ctrl1);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static struct rtc_class_ops rx8025_rtc_ops = {
+	.read_time = rx8025_get_time,
+	.set_time = rx8025_set_time,
+	.read_alarm = rx8025_read_alarm,
+	.set_alarm = rx8025_set_alarm,
+	.alarm_irq_enable = rx8025_alarm_irq_enable,
+	.irq_set_state  = rx8025_irq_set_state,
+};
+
+/*
+ * Clock precision adjustment support
+ *
+ * According to the RX8025 SA/NB application manual the frequency and
+ * temperature charateristics can be approximated using the following
+ * equation:
+ *
+ *   df = a * (ut - t)**2
+ *
+ *   df: Frequency deviation in any temperature
+ *   a : Coefficient = (-35 +-5) * 10**-9
+ *   ut: Ultimate temperature in degree = +25 +-5 degree
+ *   t : Any temperature in degree
+ *
+ * Note that the clock adjustment in ppb must be entered (which is
+ * the negative value of the deviation).
+ */
+static int rx8025_get_clock_adjust(struct device *dev, int *adj)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	u8 digoff;
+	int err;
+
+	err = rx8025_read_reg(client, RX8025_REG_DIGOFF, &digoff);
+	if (err)
+		return err;
+
+	*adj = digoff >= 64 ? digoff - 128 : digoff;
+	if (*adj > 0)
+		(*adj)--;
+	*adj *= -RX8025_ADJ_RESOLUTION;
+
+	return 0;
+}
+
+static int rx8025_set_clock_adjust(struct device *dev, int adj)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	u8 digoff;
+	int err;
+
+	adj /= -RX8025_ADJ_RESOLUTION;
+	if (adj > RX8025_ADJ_DATA_MAX)
+		adj = RX8025_ADJ_DATA_MAX;
+	else if (adj < RX8025_ADJ_DATA_MIN)
+		adj = RX8025_ADJ_DATA_MIN;
+	else if (adj > 0)
+		adj++;
+	else if (adj < 0)
+		adj += 128;
+	digoff = adj;
+
+	err = rx8025_write_reg(client, RX8025_REG_DIGOFF, digoff);
+	if (err)
+		return err;
+
+	dev_dbg(dev, "%s: write 0x%02x\n", __func__, digoff);
+
+	return 0;
+}
+
+static ssize_t rx8025_sysfs_show_clock_adjust(struct device *dev,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	int err, adj;
+
+	err = rx8025_get_clock_adjust(dev, &adj);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%d\n", adj);
+}
+
+static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
+					       struct device_attribute *attr,
+					       const char *buf, size_t count)
+{
+	int adj, err;
+
+	if (sscanf(buf, "%i", &adj) != 1)
+		return -EINVAL;
+
+	err = rx8025_set_clock_adjust(dev, adj);
+
+	return err ? err : count;
+}
+
+static DEVICE_ATTR(clock_adjust_ppb, S_IRUGO | S_IWUSR,
+		   rx8025_sysfs_show_clock_adjust,
+		   rx8025_sysfs_store_clock_adjust);
+
+static int rx8025_sysfs_register(struct device *dev)
+{
+	return device_create_file(dev, &dev_attr_clock_adjust_ppb);
+}
+
+static void rx8025_sysfs_unregister(struct device *dev)
+{
+	device_remove_file(dev, &dev_attr_clock_adjust_ppb);
+}
+
+static int __devinit rx8025_probe(struct i2c_client *client,
+				  const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+	struct rx8025_data *rx8025;
+	int err, need_reset = 0;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
+				     | I2C_FUNC_SMBUS_I2C_BLOCK)) {
+		dev_err(&adapter->dev,
+			"doesn't support required functionality\n");
+		err = -EIO;
+		goto errout;
+	}
+
+	rx8025 = kzalloc(sizeof(*rx8025), GFP_KERNEL);
+	if (!rx8025) {
+		dev_err(&adapter->dev, "failed to alloc memory\n");
+		err = -ENOMEM;
+		goto errout;
+	}
+
+	rx8025->client = client;
+	i2c_set_clientdata(client, rx8025);
+	INIT_WORK(&rx8025->work, rx8025_work);
+
+	err = rx8025_init_client(client, &need_reset);
+	if (err)
+		goto errout_free;
+
+	if (need_reset) {
+		struct rtc_time tm;
+		dev_info(&client->dev,
+			 "bad conditions detected, resetting date\n");
+		rtc_time_to_tm(0, &tm);	/* 1970/1/1 */
+		rx8025_set_time(&client->dev, &tm);
+	}
+
+	rx8025->rtc = rtc_device_register(client->name, &client->dev,
+					  &rx8025_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rx8025->rtc)) {
+		err = PTR_ERR(rx8025->rtc);
+		dev_err(&client->dev, "unable to register the class device\n");
+		goto errout_free;
+	}
+
+	if (client->irq != NO_IRQ) {
+		dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
+		err = request_irq(client->irq, rx8025_irq,
+				  0, "rx8025", client);
+		if (err) {
+			dev_err(&client->dev, "unable to request IRQ\n");
+			goto errout_reg;
+		}
+	}
+
+	rx8025->rtc->irq_freq = 1;
+	rx8025->rtc->max_user_freq = 1;
+
+	err = rx8025_sysfs_register(&client->dev);
+	if (err)
+		goto errout_irq;
+
+	return 0;
+
+errout_irq:
+	if (client->irq != NO_IRQ)
+		free_irq(client->irq, client);
+
+errout_reg:
+	rtc_device_unregister(rx8025->rtc);
+
+errout_free:
+	i2c_set_clientdata(client, NULL);
+	kfree(rx8025);
+
+errout:
+	dev_err(&adapter->dev, "probing for rx8025 failed\n");
+	return err;
+}
+
+static int __devexit rx8025_remove(struct i2c_client *client)
+{
+	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
+	struct mutex *lock = &rx8025->rtc->ops_lock;
+
+	if (client->irq != NO_IRQ) {
+		mutex_lock(lock);
+		rx8025->exiting = 1;
+		mutex_unlock(lock);
+
+		free_irq(client->irq, client);
+		flush_scheduled_work();
+	}
+
+	rx8025_sysfs_unregister(&client->dev);
+	rtc_device_unregister(rx8025->rtc);
+	i2c_set_clientdata(client, NULL);
+	kfree(rx8025);
+	return 0;
+}
+
+static struct i2c_driver rx8025_driver = {
+	.driver = {
+		.name = "rtc-rx8025",
+		.owner = THIS_MODULE,
+	},
+	.probe		= rx8025_probe,
+	.remove		= __devexit_p(rx8025_remove),
+	.id_table	= rx8025_id,
+};
+
+static int __init rx8025_init(void)
+{
+	return i2c_add_driver(&rx8025_driver);
+}
+
+static void __exit rx8025_exit(void)
+{
+	i2c_del_driver(&rx8025_driver);
+}
+
+MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
+MODULE_DESCRIPTION("RX-8025 SA/NB RTC driver");
+MODULE_LICENSE("GPL");
+
+module_init(rx8025_init);
+module_exit(rx8025_exit);