Patchwork isl12022: added Intersil ISL12022 RTC

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Submitter Roman Fietze
Date June 18, 2010, 5:27 a.m.
Message ID <201006180727.06274.roman.fietze@telemotive.de>
Download mbox | patch
Permalink /patch/56106/
State New
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Comments

Roman Fietze - June 18, 2010, 5:27 a.m.
Hallo Wan,

On Friday 18 June 2010 04:08:02 Wan ZongShun wrote:

> I have to remind you to use scripts/checkpatch.pl' to check your
> patch format. There are more warning and errors in your patch.

Ok, all done. One patch and checkpatch.pl tells me it's ok.


From 62d43961b73aafe10d1b33b0702b378cc29d0881 Mon Sep 17 00:00:00 2001
From: Roman Fietze <roman.fietze@telemotive.de>
Date: Fri, 18 Jun 2010 07:20:44 +0200
Subject: [PATCH] isl12022: add Intersil ISL12022 RTC driver

- derived from rtc-pcf8563
- no SRAM driver

Signed-off-by: Roman Fietze <roman.fietze@telemotive.de>
---
 drivers/rtc/Kconfig        |    9 ++
 drivers/rtc/Makefile       |    1 +
 drivers/rtc/rtc-isl12022.c |  327 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 337 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-isl12022.c
Wan ZongShun - June 18, 2010, 5:33 a.m.
2010/6/18 Roman Fietze <roman.fietze@telemotive.de>:
> Hallo Wan,
>
> On Friday 18 June 2010 04:08:02 Wan ZongShun wrote:
>
>> I have to remind you to use scripts/checkpatch.pl' to check your
>> patch format. There are more warning and errors in your patch.
>
> Ok, all done. One patch and checkpatch.pl tells me it's ok.
>

Hmmm, which mail client was used by you?
It seem to have destroyed your patch.

Would you mind sending your patch to me as attached file?
I will help you fix this issue.

>
> From 62d43961b73aafe10d1b33b0702b378cc29d0881 Mon Sep 17 00:00:00 2001
> From: Roman Fietze <roman.fietze@telemotive.de>
> Date: Fri, 18 Jun 2010 07:20:44 +0200
> Subject: [PATCH] isl12022: add Intersil ISL12022 RTC driver
>
> - derived from rtc-pcf8563
> - no SRAM driver
>
> Signed-off-by: Roman Fietze <roman.fietze@telemotive.de>
> ---
>  drivers/rtc/Kconfig        |    9 ++
>  drivers/rtc/Makefile       |    1 +
>  drivers/rtc/rtc-isl12022.c |  327 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 337 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-isl12022.c
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 6a13037..ade6427 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -203,6 +203,15 @@ config RTC_DRV_ISL1208
>          This driver can also be built as a module. If so, the module
>          will be called rtc-isl1208.
>
> +config RTC_DRV_ISL12022
> +       tristate "Intersil ISL12022"
> +       help
> +         If you say yes here you get support for the
> +         Intersil ISL12022 RTC chip.
> +
> +         This driver can also be built as a module. If so, the module
> +         will be called rtc-isl12022.
> +
>  config RTC_DRV_X1205
>        tristate "Xicor/Intersil X1205"
>        help
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 44ef194..782d516 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -45,6 +45,7 @@ obj-$(CONFIG_RTC_DRV_EP93XX)  += rtc-ep93xx.o
>  obj-$(CONFIG_RTC_DRV_FM3130)   += rtc-fm3130.o
>  obj-$(CONFIG_RTC_DRV_GENERIC)  += rtc-generic.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)  += rtc-isl1208.o
> +obj-$(CONFIG_RTC_DRV_ISL12022) += rtc-isl12022.o
>  obj-$(CONFIG_RTC_DRV_M41T80)   += rtc-m41t80.o
>  obj-$(CONFIG_RTC_DRV_M41T94)   += rtc-m41t94.o
>  obj-$(CONFIG_RTC_DRV_M48T35)   += rtc-m48t35.o
> diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
> new file mode 100644
> index 0000000..4a8c9dd
> --- /dev/null
> +++ b/drivers/rtc/rtc-isl12022.c
> @@ -0,0 +1,327 @@
> +/*
> + * An I2C driver for the Intersil ISL 12022
> + *
> + * Author: Roman Fietze <roman.fietze@telemotive.de>
> + *
> + * Based on the Philips PCF8563 RTC
> + * by Alessandro Zummo <a.zummo@towertech.it>.
> + *
> + * 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/i2c.h>
> +#include <linux/bcd.h>
> +#include <linux/rtc.h>
> +#include <linux/slab.h>
> +
> +#define DRV_VERSION "0.1"
> +
> +/* ISL register offsets */
> +#define ISL12022_REG_SC                0x00
> +#define ISL12022_REG_MN                0x01
> +#define ISL12022_REG_HR                0x02
> +#define ISL12022_REG_DT                0x03
> +#define ISL12022_REG_MO                0x04
> +#define ISL12022_REG_YR                0x05
> +#define ISL12022_REG_DW                0x06
> +
> +#define ISL12022_REG_SR                0x07
> +#define ISL12022_REG_INT       0x08
> +
> +/* ISL register bits */
> +#define ISL12022_HR_MIL                (1 << 7)        /* military or 24 hour time */
> +
> +#define ISL12022_SR_LBAT85     (1 << 2)
> +#define ISL12022_SR_LBAT75     (1 << 1)
> +
> +#define ISL12022_INT_WRTC      (1 << 6)
> +
> +
> +static struct i2c_driver isl12022_driver;
> +
> +struct isl12022 {
> +       struct rtc_device *rtc;
> +
> +       bool write_enabled;     /* true if write enable is set */
> +};
> +
> +
> +static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
> +                             uint8_t *data, size_t n)
> +{
> +       struct i2c_msg msgs[] = {
> +               {
> +                       .addr   = client->addr,
> +                       .flags  = 0,
> +                       .len    = 1,
> +                       .buf    = data
> +               },              /* setup read ptr */
> +               {
> +                       .addr   = client->addr,
> +                       .flags  = I2C_M_RD,
> +                       .len    = n,
> +                       .buf    = data
> +               }
> +       };
> +
> +       int ret;
> +
> +       data[0] = reg;
> +       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
> +       if (ret != ARRAY_SIZE(msgs)) {
> +               dev_err(&client->dev, "%s: read error, ret=%d\n",
> +                       __func__, ret);
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}
> +
> +
> +static int isl12022_write_reg(struct i2c_client *client,
> +                             uint8_t reg, uint8_t val)
> +{
> +       uint8_t data[2] = { reg, val };
> +       int err;
> +
> +       err = i2c_master_send(client, data, sizeof(data));
> +       if (err != sizeof(data)) {
> +               dev_err(&client->dev,
> +                       "%s: err=%d addr=%02x, data=%02x\n",
> +                       __func__, err, data[0], data[1]);
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}
> +
> +
> +/*
> + * In the routines that deal directly with the isl12022 hardware, we use
> + * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
> + */
> +static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
> +{
> +       uint8_t buf[ISL12022_REG_INT + 1];
> +       int ret;
> +
> +       ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
> +       if (ret)
> +               return ret;
> +
> +       if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
> +               dev_warn(&client->dev,
> +                        "voltage dropped below %u%%, "
> +                        "date and time is not reliable.\n",
> +                        buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
> +       }
> +
> +       dev_dbg(&client->dev,
> +               "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
> +               "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
> +               "sr=%02x, int=%02x",
> +               __func__,
> +               buf[ISL12022_REG_SC],
> +               buf[ISL12022_REG_MN],
> +               buf[ISL12022_REG_HR],
> +               buf[ISL12022_REG_DT],
> +               buf[ISL12022_REG_MO],
> +               buf[ISL12022_REG_YR],
> +               buf[ISL12022_REG_DW],
> +               buf[ISL12022_REG_SR],
> +               buf[ISL12022_REG_INT]);
> +
> +       tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
> +       tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
> +       tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
> +       tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
> +       tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
> +       tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
> +       tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
> +
> +       dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
> +               "mday=%d, mon=%d, year=%d, wday=%d\n",
> +               __func__,
> +               tm->tm_sec, tm->tm_min, tm->tm_hour,
> +               tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
> +
> +       /* The clock can give out invalid datetime, but we cannot return
> +        * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
> +       if (rtc_valid_tm(tm) < 0)
> +               dev_err(&client->dev, "retrieved date and time is invalid.\n");
> +
> +       return 0;
> +}
> +
> +static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
> +{
> +       struct isl12022 *isl12022 = i2c_get_clientdata(client);
> +       size_t i;
> +       int ret;
> +       uint8_t buf[ISL12022_REG_DW + 1];
> +
> +       dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
> +               "mday=%d, mon=%d, year=%d, wday=%d\n",
> +               __func__,
> +               tm->tm_sec, tm->tm_min, tm->tm_hour,
> +               tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
> +
> +       if (!isl12022->write_enabled) {
> +
> +               ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
> +               if (ret)
> +                       return ret;
> +
> +               /* Check if WRTC (write rtc enable) is set factory default is
> +                * 0 (not set) */
> +               if (!(buf[0] & ISL12022_INT_WRTC)) {
> +                       dev_info(&client->dev,
> +                                "init write enable and 24 hour format\n");
> +
> +                       /* Set the write enable bit. */
> +                       ret = isl12022_write_reg(client,
> +                                                ISL12022_REG_INT,
> +                                                buf[0] | ISL12022_INT_WRTC);
> +                       if (ret)
> +                               return ret;
> +
> +                       /* Write to any RTC register to start RTC, we use the
> +                        * HR register, setting the MIL bit to use the 24 hour
> +                        * format. */
> +                       ret = isl12022_read_regs(client, ISL12022_REG_HR,
> +                                                buf, 1);
> +                       if (ret)
> +                               return ret;
> +
> +                       ret = isl12022_write_reg(client,
> +                                                ISL12022_REG_HR,
> +                                                buf[0] | ISL12022_HR_MIL);
> +                       if (ret)
> +                               return ret;
> +               }
> +
> +               isl12022->write_enabled = 1;
> +       }
> +
> +       /* hours, minutes and seconds */
> +       buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
> +       buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
> +       buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour);
> +
> +       buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
> +
> +       /* month, 1 - 12 */
> +       buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
> +
> +       /* year and century */
> +       buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
> +
> +       buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
> +
> +       /* write register's data */
> +       for (i = 0; i < ARRAY_SIZE(buf); i++) {
> +               ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
> +                                        buf[ISL12022_REG_SC + i]);
> +               if (ret)
> +                       return -EIO;
> +       };
> +
> +       return 0;
> +}
> +
> +static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +       return isl12022_get_datetime(to_i2c_client(dev), tm);
> +}
> +
> +static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +       return isl12022_set_datetime(to_i2c_client(dev), tm);
> +}
> +
> +static const struct rtc_class_ops isl12022_rtc_ops = {
> +       .read_time      = isl12022_rtc_read_time,
> +       .set_time       = isl12022_rtc_set_time,
> +};
> +
> +static int isl12022_probe(struct i2c_client *client,
> +                         const struct i2c_device_id *id)
> +{
> +       struct isl12022 *isl12022;
> +
> +       int ret = 0;
> +
> +       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> +               return -ENODEV;
> +
> +       isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
> +       if (!isl12022)
> +               return -ENOMEM;
> +
> +       dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
> +
> +       i2c_set_clientdata(client, isl12022);
> +
> +       isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
> +                                           &client->dev,
> +                                           &isl12022_rtc_ops,
> +                                           THIS_MODULE);
> +
> +       if (IS_ERR(isl12022->rtc)) {
> +               ret = PTR_ERR(isl12022->rtc);
> +               goto exit_kfree;
> +       }
> +
> +       return 0;
> +
> +exit_kfree:
> +       kfree(isl12022);
> +
> +       return ret;
> +}
> +
> +static int isl12022_remove(struct i2c_client *client)
> +{
> +       struct isl12022 *isl12022 = i2c_get_clientdata(client);
> +
> +       rtc_device_unregister(isl12022->rtc);
> +       kfree(isl12022);
> +
> +       return 0;
> +}
> +
> +static const struct i2c_device_id isl12022_id[] = {
> +       { "isl12022", 0 },
> +       { "rtc8564", 0 },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(i2c, isl12022_id);
> +
> +static struct i2c_driver isl12022_driver = {
> +       .driver         = {
> +               .name   = "rtc-isl12022",
> +       },
> +       .probe          = isl12022_probe,
> +       .remove         = isl12022_remove,
> +       .id_table       = isl12022_id,
> +};
> +
> +static int __init isl12022_init(void)
> +{
> +       return i2c_add_driver(&isl12022_driver);
> +}
> +
> +static void __exit isl12022_exit(void)
> +{
> +       i2c_del_driver(&isl12022_driver);
> +}
> +
> +module_init(isl12022_init);
> +module_exit(isl12022_exit);
> +
> +MODULE_AUTHOR("roman.fietze@telemotive.de");
> +MODULE_DESCRIPTION("ISL 12022 RTC driver");
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(DRV_VERSION);
> --
> 1.7.1
>
>
> --
> Roman Fietze                Telemotive AG Büro Mühlhausen
> Breitwiesen                              73347 Mühlhausen
> Tel.: +49(0)7335/18493-45        http://www.telemotive.de
>

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6a13037..ade6427 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -203,6 +203,15 @@  config RTC_DRV_ISL1208
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-isl1208.
 
+config RTC_DRV_ISL12022
+	tristate "Intersil ISL12022"
+	help
+	  If you say yes here you get support for the
+	  Intersil ISL12022 RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-isl12022.
+
 config RTC_DRV_X1205
 	tristate "Xicor/Intersil X1205"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 44ef194..782d516 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -45,6 +45,7 @@  obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
+obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
 obj-$(CONFIG_RTC_DRV_M41T80)	+= rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M41T94)	+= rtc-m41t94.o
 obj-$(CONFIG_RTC_DRV_M48T35)	+= rtc-m48t35.o
diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
new file mode 100644
index 0000000..4a8c9dd
--- /dev/null
+++ b/drivers/rtc/rtc-isl12022.c
@@ -0,0 +1,327 @@ 
+/*
+ * An I2C driver for the Intersil ISL 12022
+ *
+ * Author: Roman Fietze <roman.fietze@telemotive.de>
+ *
+ * Based on the Philips PCF8563 RTC
+ * by Alessandro Zummo <a.zummo@towertech.it>.
+ *
+ * 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/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+#define DRV_VERSION "0.1"
+
+/* ISL register offsets */
+#define ISL12022_REG_SC		0x00
+#define ISL12022_REG_MN		0x01
+#define ISL12022_REG_HR		0x02
+#define ISL12022_REG_DT		0x03
+#define ISL12022_REG_MO		0x04
+#define ISL12022_REG_YR		0x05
+#define ISL12022_REG_DW		0x06
+
+#define ISL12022_REG_SR		0x07
+#define ISL12022_REG_INT	0x08
+
+/* ISL register bits */
+#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
+
+#define ISL12022_SR_LBAT85	(1 << 2)
+#define ISL12022_SR_LBAT75	(1 << 1)
+
+#define ISL12022_INT_WRTC	(1 << 6)
+
+
+static struct i2c_driver isl12022_driver;
+
+struct isl12022 {
+	struct rtc_device *rtc;
+
+	bool write_enabled;	/* true if write enable is set */
+};
+
+
+static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
+			      uint8_t *data, size_t n)
+{
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= data
+		},		/* setup read ptr */
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= n,
+			.buf	= data
+		}
+	};
+
+	int ret;
+
+	data[0] = reg;
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "%s: read error, ret=%d\n",
+			__func__, ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+
+static int isl12022_write_reg(struct i2c_client *client,
+			      uint8_t reg, uint8_t val)
+{
+	uint8_t data[2] = { reg, val };
+	int err;
+
+	err = i2c_master_send(client, data, sizeof(data));
+	if (err != sizeof(data)) {
+		dev_err(&client->dev,
+			"%s: err=%d addr=%02x, data=%02x\n",
+			__func__, err, data[0], data[1]);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+
+/*
+ * In the routines that deal directly with the isl12022 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	uint8_t buf[ISL12022_REG_INT + 1];
+	int ret;
+
+	ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
+		dev_warn(&client->dev,
+			 "voltage dropped below %u%%, "
+			 "date and time is not reliable.\n",
+			 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
+	}
+
+	dev_dbg(&client->dev,
+		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "
+		"mday=%02x, mon=%02x, year=%02x, wday=%02x, "
+		"sr=%02x, int=%02x",
+		__func__,
+		buf[ISL12022_REG_SC],
+		buf[ISL12022_REG_MN],
+		buf[ISL12022_REG_HR],
+		buf[ISL12022_REG_DT],
+		buf[ISL12022_REG_MO],
+		buf[ISL12022_REG_YR],
+		buf[ISL12022_REG_DW],
+		buf[ISL12022_REG_SR],
+		buf[ISL12022_REG_INT]);
+
+	tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
+	tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
+	tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
+	tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
+	tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
+	tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
+	tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
+
+	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__func__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	/* The clock can give out invalid datetime, but we cannot return
+	 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
+	if (rtc_valid_tm(tm) < 0)
+		dev_err(&client->dev, "retrieved date and time is invalid.\n");
+
+	return 0;
+}
+
+static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	struct isl12022 *isl12022 = i2c_get_clientdata(client);
+	size_t i;
+	int ret;
+	uint8_t buf[ISL12022_REG_DW + 1];
+
+	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
+		"mday=%d, mon=%d, year=%d, wday=%d\n",
+		__func__,
+		tm->tm_sec, tm->tm_min, tm->tm_hour,
+		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	if (!isl12022->write_enabled) {
+
+		ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
+		if (ret)
+			return ret;
+
+		/* Check if WRTC (write rtc enable) is set factory default is
+		 * 0 (not set) */
+		if (!(buf[0] & ISL12022_INT_WRTC)) {
+			dev_info(&client->dev,
+				 "init write enable and 24 hour format\n");
+
+			/* Set the write enable bit. */
+			ret = isl12022_write_reg(client,
+						 ISL12022_REG_INT,
+						 buf[0] | ISL12022_INT_WRTC);
+			if (ret)
+				return ret;
+
+			/* Write to any RTC register to start RTC, we use the
+			 * HR register, setting the MIL bit to use the 24 hour
+			 * format. */
+			ret = isl12022_read_regs(client, ISL12022_REG_HR,
+						 buf, 1);
+			if (ret)
+				return ret;
+
+			ret = isl12022_write_reg(client,
+						 ISL12022_REG_HR,
+						 buf[0] | ISL12022_HR_MIL);
+			if (ret)
+				return ret;
+		}
+
+		isl12022->write_enabled = 1;
+	}
+
+	/* hours, minutes and seconds */
+	buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
+	buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
+	buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour);
+
+	buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
+
+	/* month, 1 - 12 */
+	buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
+
+	/* year and century */
+	buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
+
+	buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
+
+	/* write register's data */
+	for (i = 0; i < ARRAY_SIZE(buf); i++) {
+		ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
+					 buf[ISL12022_REG_SC + i]);
+		if (ret)
+			return -EIO;
+	};
+
+	return 0;
+}
+
+static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return isl12022_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return isl12022_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops isl12022_rtc_ops = {
+	.read_time	= isl12022_rtc_read_time,
+	.set_time	= isl12022_rtc_set_time,
+};
+
+static int isl12022_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct isl12022 *isl12022;
+
+	int ret = 0;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
+	if (!isl12022)
+		return -ENOMEM;
+
+	dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+	i2c_set_clientdata(client, isl12022);
+
+	isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
+					    &client->dev,
+					    &isl12022_rtc_ops,
+					    THIS_MODULE);
+
+	if (IS_ERR(isl12022->rtc)) {
+		ret = PTR_ERR(isl12022->rtc);
+		goto exit_kfree;
+	}
+
+	return 0;
+
+exit_kfree:
+	kfree(isl12022);
+
+	return ret;
+}
+
+static int isl12022_remove(struct i2c_client *client)
+{
+	struct isl12022 *isl12022 = i2c_get_clientdata(client);
+
+	rtc_device_unregister(isl12022->rtc);
+	kfree(isl12022);
+
+	return 0;
+}
+
+static const struct i2c_device_id isl12022_id[] = {
+	{ "isl12022", 0 },
+	{ "rtc8564", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, isl12022_id);
+
+static struct i2c_driver isl12022_driver = {
+	.driver		= {
+		.name	= "rtc-isl12022",
+	},
+	.probe		= isl12022_probe,
+	.remove		= isl12022_remove,
+	.id_table	= isl12022_id,
+};
+
+static int __init isl12022_init(void)
+{
+	return i2c_add_driver(&isl12022_driver);
+}
+
+static void __exit isl12022_exit(void)
+{
+	i2c_del_driver(&isl12022_driver);
+}
+
+module_init(isl12022_init);
+module_exit(isl12022_exit);
+
+MODULE_AUTHOR("roman.fietze@telemotive.de");
+MODULE_DESCRIPTION("ISL 12022 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);