rtc: add EM3027 rtc driver

Add support for EM Microelectronic EM3027 RTC chip.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 171 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 3db52f01d458..512b40ea32cd 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -361,6 +361,15 @@ config RTC_DRV_RX8025
           This driver can also be built as a module. If so, the module
           will be called rtc-rx8025.
 
+config RTC_DRV_EM3027
+        tristate "EM Microelectronic EM3027"
+        help
+          If you say yes here you get support for the EM
+          Microelectronic EM3027 RTC chips.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-em3027.
+
 endif # I2C
 
 comment "SPI RTC drivers"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 986f17e51df8..4801a0af7bcd 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
 obj-$(CONFIG_RTC_DRV_DS3232)    += rtc-ds3232.o
 obj-$(CONFIG_RTC_DRV_DS3234)    += rtc-ds3234.o
 obj-$(CONFIG_RTC_DRV_EFI)       += rtc-efi.o
+obj-$(CONFIG_RTC_DRV_EM3027)    += rtc-em3027.o
 obj-$(CONFIG_RTC_DRV_EP93XX)    += rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)    += rtc-fm3130.o
 obj-$(CONFIG_RTC_DRV_GENERIC)   += rtc-generic.o
diff --git a/drivers/rtc/rtc-em3027.c b/drivers/rtc/rtc-em3027.c
new file mode 100644
index 000000000000..d8e1c2578553
--- /dev/null
+++ b/drivers/rtc/rtc-em3027.c
@@ -0,0 +1,161 @@
+/*
+ * An rtc/i2c driver for the EM Microelectronic EM3027
+ * Copyright 2011 CompuLab, Ltd.
+ *
+ * Author: Mike Rapoport <mike@compulab.co.il>
+ *
+ * Based on rtc-ds1672.c 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/rtc.h>
+#include <linux/bcd.h>
+
+/* Registers */
+#define EM3027_REG_ON_OFF_CTRL  0x00
+#define EM3027_REG_IRQ_CTRL     0x01
+#define EM3027_REG_IRQ_FLAGS    0x02
+#define EM3027_REG_STATUS       0x03
+#define EM3027_REG_RST_CTRL     0x04
+
+#define EM3027_REG_WATCH_SEC    0x08
+#define EM3027_REG_WATCH_MIN    0x09
+#define EM3027_REG_WATCH_HOUR   0x0a
+#define EM3027_REG_WATCH_DATE   0x0b
+#define EM3027_REG_WATCH_DAY    0x0c
+#define EM3027_REG_WATCH_MON    0x0d
+#define EM3027_REG_WATCH_YEAR   0x0e
+
+#define EM3027_REG_ALARM_SEC    0x10
+#define EM3027_REG_ALARM_MIN    0x11
+#define EM3027_REG_ALARM_HOUR   0x12
+#define EM3027_REG_ALARM_DATE   0x13
+#define EM3027_REG_ALARM_DAY    0x14
+#define EM3027_REG_ALARM_MON    0x15
+#define EM3027_REG_ALARM_YEAR   0x16
+
+static struct i2c_driver em3027_driver;
+
+static int em3027_get_time(struct device *dev, struct rtc_time *tm)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+
+        unsigned char addr = EM3027_REG_WATCH_SEC;
+        unsigned char buf[7];
+
+        struct i2c_msg msgs[] = {
+                {client->addr, 0, 1, &addr},            /* setup read addr */
+                {client->addr, I2C_M_RD, 7, buf},       /* read time/date */
+        };
+
+        /* read time/date registers */
+        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+                dev_err(&client->dev, "%s: read error\n", __func__);
+                return -EIO;
+        }
+
+        tm->tm_sec      = bcd2bin(buf[0]);
+        tm->tm_min      = bcd2bin(buf[1]);
+        tm->tm_hour     = bcd2bin(buf[2]);
+        tm->tm_mday     = bcd2bin(buf[3]);
+        tm->tm_wday     = bcd2bin(buf[4]);
+        tm->tm_mon      = bcd2bin(buf[5]);
+        tm->tm_year     = bcd2bin(buf[6]) + 100;
+
+        return 0;
+}
+
+static int em3027_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        unsigned char buf[8];
+
+        struct i2c_msg msg = {
+                client->addr, 0, 8, buf,        /* write time/date */
+        };
+
+        buf[0] = EM3027_REG_WATCH_SEC;
+        buf[1] = bin2bcd(tm->tm_sec);
+        buf[2] = bin2bcd(tm->tm_min);
+        buf[3] = bin2bcd(tm->tm_hour);
+        buf[4] = bin2bcd(tm->tm_mday);
+        buf[5] = bin2bcd(tm->tm_wday);
+        buf[6] = bin2bcd(tm->tm_mon);
+        buf[7] = bin2bcd(tm->tm_year % 100);
+
+        /* write time/date registers */
+        if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
+                dev_err(&client->dev, "%s: write error\n", __func__);
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static const struct rtc_class_ops em3027_rtc_ops = {
+        .read_time = em3027_get_time,
+        .set_time = em3027_set_time,
+};
+
+static int em3027_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        struct rtc_device *rtc;
+
+        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+                return -ENODEV;
+
+        rtc = rtc_device_register(em3027_driver.driver.name, &client->dev,
+                                  &em3027_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
+
+        i2c_set_clientdata(client, rtc);
+
+        return 0;
+}
+
+static int em3027_remove(struct i2c_client *client)
+{
+        struct rtc_device *rtc = i2c_get_clientdata(client);
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        return 0;
+}
+
+static struct i2c_device_id em3027_id[] = {
+        { "em3027", 0 },
+        { }
+};
+
+static struct i2c_driver em3027_driver = {
+        .driver = {
+                   .name = "rtc-em3027",
+        },
+        .probe = &em3027_probe,
+        .remove = &em3027_remove,
+        .id_table = em3027_id,
+};
+
+static int __init em3027_init(void)
+{
+        return i2c_add_driver(&em3027_driver);
+}
+
+static void __exit em3027_exit(void)
+{
+        i2c_del_driver(&em3027_driver);
+}
+
+MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
+MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
+MODULE_LICENSE("GPL");
+
+module_init(em3027_init);
+module_exit(em3027_exit);