rtc: add stand-alone driver for RX8025 chip
authorWolfgang Grandegger <wg@grandegger.com>
Wed, 17 Jun 2009 23:26:11 +0000 (16:26 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 18 Jun 2009 20:03:43 +0000 (13:03 -0700)
Add 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>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/rtc/Kconfig
drivers/rtc/Makefile
drivers/rtc/rtc-rx8025.c [new file with mode: 0644]

index 277d35d..81adbdb 100644 (file)
@@ -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"
index 6c0639a..3c0f2b2 100644 (file)
@@ -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 (file)
index 0000000..b1a29bc
--- /dev/null
@@ -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.
+ *
+ * Modified 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 <= 0)
+               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 <= 0)
+               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 <= 0)
+               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 > 0) {
+               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 > 0)
+               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 > 0) {
+               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);