rtc: basic implementation of Epson RX-8581 I2C Real Time Clock
authorMartyn Welch <martyn.welch@gefanuc.com>
Wed, 12 Nov 2008 21:27:06 +0000 (13:27 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 13 Nov 2008 01:17:18 +0000 (17:17 -0800)
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>
drivers/rtc/Kconfig
drivers/rtc/Makefile
drivers/rtc/rtc-rx8581.c [new file with mode: 0644]

index 7951ad2fd995199a223cf7a173273014512c248a..990020c1dae9696782d18a77cbe07512eed3296f 100644 (file)
@@ -277,6 +277,14 @@ config RTC_DRV_FM3130
          This driver can also be built as a module. If so the module
          will be called rtc-fm3130.
 
+config RTC_DRV_RX8581
+       tristate "Epson RX-8581"
+       help
+         If you say yes here you will get support for the Epson RX-8581.
+
+         This driver can also be built as a module. If so the module
+         will be called rtc-rx8581.
+
 endif # I2C
 
 comment "SPI RTC drivers"
index 7a41201e7efdd124809a5c4e532bb66a1e8f8502..16368600643cb3a88b15f32371dde41276cdf9a4 100644 (file)
@@ -57,6 +57,7 @@ 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-$(CONFIG_RTC_DRV_RX8581)   += rtc-rx8581.o
 obj-$(CONFIG_RTC_DRV_S35390A)  += rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)      += rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_SA1100)   += rtc-sa1100.o
diff --git a/drivers/rtc/rtc-rx8581.c b/drivers/rtc/rtc-rx8581.c
new file mode 100644 (file)
index 0000000..c9522f3
--- /dev/null
@@ -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);