rtc: basic implementation of Epson RX-8581 I2C Real Time Clock

Provide the basic "get" and "set" functionality for the Epson RX-8581 I2C
RTC.  It currently does not support the RTC's Alarm or Fixed-cycle timer.

[akpm@linux-foundation.org: need log2.h for ilog2(), remove unneeded initialisation]
Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 281 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-rx8581.c b/drivers/rtc/rtc-rx8581.c
new file mode 100644
index 000000000000..c9522f3bc21c
--- /dev/null
+++ b/drivers/rtc/rtc-rx8581.c
@@ -0,0 +1,281 @@
+/*
+ * An I2C driver for the Epson RX8581 RTC
+ *
+ * Author: Martyn Welch <martyn.welch@gefanuc.com>
+ * Copyright 2008 GE Fanuc Intelligent Platforms Embedded Systems, Inc.
+ *
+ * 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.
+ *
+ * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
+ * Copyright 2005-06 Tower Technologies
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/log2.h>
+
+#define DRV_VERSION "0.1"
+
+#define RX8581_REG_SC           0x00 /* Second in BCD */
+#define RX8581_REG_MN           0x01 /* Minute in BCD */
+#define RX8581_REG_HR           0x02 /* Hour in BCD */
+#define RX8581_REG_DW           0x03 /* Day of Week */
+#define RX8581_REG_DM           0x04 /* Day of Month in BCD */
+#define RX8581_REG_MO           0x05 /* Month in BCD */
+#define RX8581_REG_YR           0x06 /* Year in BCD */
+#define RX8581_REG_RAM          0x07 /* RAM */
+#define RX8581_REG_AMN          0x08 /* Alarm Min in BCD*/
+#define RX8581_REG_AHR          0x09 /* Alarm Hour in BCD */
+#define RX8581_REG_ADM          0x0A
+#define RX8581_REG_ADW          0x0A
+#define RX8581_REG_TMR0         0x0B
+#define RX8581_REG_TMR1         0x0C
+#define RX8581_REG_EXT          0x0D /* Extension Register */
+#define RX8581_REG_FLAG         0x0E /* Flag Register */
+#define RX8581_REG_CTRL         0x0F /* Control Register */
+
+
+/* Flag Register bit definitions */
+#define RX8581_FLAG_UF          0x20 /* Update */
+#define RX8581_FLAG_TF          0x10 /* Timer */
+#define RX8581_FLAG_AF          0x08 /* Alarm */
+#define RX8581_FLAG_VLF         0x02 /* Voltage Low */
+
+/* Control Register bit definitions */
+#define RX8581_CTRL_UIE         0x20 /* Update Interrupt Enable */
+#define RX8581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
+#define RX8581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
+#define RX8581_CTRL_STOP        0x02 /* STOP bit */
+#define RX8581_CTRL_RESET       0x01 /* RESET bit */
+
+static struct i2c_driver rx8581_driver;
+
+/*
+ * In the routines that deal directly with the rx8581 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        unsigned char date[7];
+        int data, err;
+
+        /* First we ensure that the "update flag" is not set, we read the
+         * time and date then re-read the "update flag". If the update flag
+         * has been set, we know that the time has changed during the read so
+         * we repeat the whole process again.
+         */
+        data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
+        if (data < 0) {
+                dev_err(&client->dev, "Unable to read device flags\n");
+                return -EIO;
+        }
+
+        do {
+                /* If update flag set, clear it */
+                if (data & RX8581_FLAG_UF) {
+                        err = i2c_smbus_write_byte_data(client,
+                                RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
+                        if (err != 0) {
+                                dev_err(&client->dev, "Unable to write device "
+                                        "flags\n");
+                                return -EIO;
+                        }
+                }
+
+                /* Now read time and date */
+                err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
+                        7, date);
+                if (err < 0) {
+                        dev_err(&client->dev, "Unable to read date\n");
+                        return -EIO;
+                }
+
+                /* Check flag register */
+                data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
+                if (data < 0) {
+                        dev_err(&client->dev, "Unable to read device flags\n");
+                        return -EIO;
+                }
+        } while (data & RX8581_FLAG_UF);
+
+        if (data & RX8581_FLAG_VLF)
+                dev_info(&client->dev,
+                        "low voltage detected, date/time is not reliable.\n");
+
+        dev_dbg(&client->dev,
+                "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
+                "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
+                __func__,
+                date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
+
+        tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
+        tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
+        tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
+        tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
+        tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
+        tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
+        tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
+        if (tm->tm_year < 70)
+                tm->tm_year += 100;     /* assume we are in 1970...2069 */
+
+
+        dev_dbg(&client->dev, "%s: tm is 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);
+
+        err = rtc_valid_tm(tm);
+        if (err < 0)
+                dev_err(&client->dev, "retrieved date/time is not valid.\n");
+
+        return err;
+}
+
+static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+        int data, err;
+        unsigned char buf[7];
+
+        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);
+
+        /* hours, minutes and seconds */
+        buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
+        buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
+        buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
+
+        buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
+
+        /* month, 1 - 12 */
+        buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
+
+        /* year and century */
+        buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
+        buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
+
+        /* Stop the clock */
+        data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
+        if (data < 0) {
+                dev_err(&client->dev, "Unable to read control register\n");
+                return -EIO;
+        }
+
+        err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
+                (data | RX8581_CTRL_STOP));
+        if (err < 0) {
+                dev_err(&client->dev, "Unable to write control register\n");
+                return -EIO;
+        }
+
+        /* write register's data */
+        err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
+        if (err < 0) {
+                dev_err(&client->dev, "Unable to write to date registers\n");
+                return -EIO;
+        }
+
+        /* Restart the clock */
+        data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
+        if (data < 0) {
+                dev_err(&client->dev, "Unable to read control register\n");
+                return -EIO;
+        }
+
+        err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
+                (data | ~(RX8581_CTRL_STOP)));
+        if (err != 0) {
+                dev_err(&client->dev, "Unable to write control register\n");
+                return -EIO;
+        }
+
+        return 0;
+}
+
+static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        return rx8581_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        return rx8581_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops rx8581_rtc_ops = {
+        .read_time      = rx8581_rtc_read_time,
+        .set_time       = rx8581_rtc_set_time,
+};
+
+static int __devinit rx8581_probe(struct i2c_client *client,
+                                const struct i2c_device_id *id)
+{
+        struct rtc_device *rtc;
+
+        dev_dbg(&client->dev, "%s\n", __func__);
+
+        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+                return -ENODEV;
+
+        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+        rtc = rtc_device_register(rx8581_driver.driver.name,
+                                &client->dev, &rx8581_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
+
+        i2c_set_clientdata(client, rtc);
+
+        return 0;
+}
+
+static int __devexit rx8581_remove(struct i2c_client *client)
+{
+        struct rtc_device *rtc = i2c_get_clientdata(client);
+
+        rtc_device_unregister(rtc);
+
+        return 0;
+}
+
+static const struct i2c_device_id rx8581_id[] = {
+        { "rx8581", 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, rx8581_id);
+
+static struct i2c_driver rx8581_driver = {
+        .driver         = {
+                .name   = "rtc-rx8581",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = rx8581_probe,
+        .remove         = __devexit_p(rx8581_remove),
+        .id_table       = rx8581_id,
+};
+
+static int __init rx8581_init(void)
+{
+        return i2c_add_driver(&rx8581_driver);
+}
+
+static void __exit rx8581_exit(void)
+{
+        i2c_del_driver(&rx8581_driver);
+}
+
+MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com>");
+MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(rx8581_init);
+module_exit(rx8581_exit);