rtc: add EPSON RX8025 support to DS1307 RTC driver

Add support for the EPSON RX8025 RTC.  The date/time registers of this
chip are compatible with the DS1307.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
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>

1 files changed, 80 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 1c975e6439b3..2c4a65302a9d 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -3,6 +3,7 @@
  *
  *  Copyright (C) 2005 James Chapman (ds1337 core)
  *  Copyright (C) 2006 David Brownell
+ *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
  *
  * 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
@@ -31,6 +32,7 @@ enum ds_type {
         ds_1339,
         ds_1340,
         m41t00,
+        rx_8025,
         // rs5c372 too?  different address...
 };
 
@@ -83,6 +85,12 @@ enum ds_type {
 #define DS1339_REG_ALARM1_SECS  0x07
 #define DS1339_REG_TRICKLE      0x10
 
+#define RX8025_REG_CTRL1        0x0e
+#       define RX8025_BIT_2412          0x20
+#define RX8025_REG_CTRL2        0x0f
+#       define RX8025_BIT_PON           0x10
+#       define RX8025_BIT_VDET          0x40
+#       define RX8025_BIT_XST           0x20
 
 
 struct ds1307 {
@@ -121,6 +129,8 @@ static const struct chip_desc chips[] = {
 [ds_1340] = {
 },
 [m41t00] = {
+},
+[rx_8025] = {
 }, };
 
 static const struct i2c_device_id ds1307_id[] = {
@@ -130,6 +140,7 @@ static const struct i2c_device_id ds1307_id[] = {
         { "ds1339", ds_1339 },
         { "ds1340", ds_1340 },
         { "m41t00", m41t00 },
+        { "rx8025", rx_8025 },
         { }
 };
 MODULE_DEVICE_TABLE(i2c, ds1307_id);
@@ -674,6 +685,72 @@ static int __devinit ds1307_probe(struct i2c_client *client,
                         dev_warn(&client->dev, "SET TIME!\n");
                 }
                 break;
+
+        case rx_8025:
+                tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+                                RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
+                if (tmp != 2) {
+                        pr_debug("read error %d\n", tmp);
+                        err = -EIO;
+                        goto exit_free;
+                }
+
+                /* oscillator off?  turn it on, so clock can tick. */
+                if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
+                        ds1307->regs[1] |= RX8025_BIT_XST;
+                        i2c_smbus_write_byte_data(client,
+                                                  RX8025_REG_CTRL2 << 4 | 0x08,
+                                                  ds1307->regs[1]);
+                        dev_warn(&client->dev,
+                                 "oscillator stop detected - SET TIME!\n");
+                }
+
+                if (ds1307->regs[1] & RX8025_BIT_PON) {
+                        ds1307->regs[1] &= ~RX8025_BIT_PON;
+                        i2c_smbus_write_byte_data(client,
+                                                  RX8025_REG_CTRL2 << 4 | 0x08,
+                                                  ds1307->regs[1]);
+                        dev_warn(&client->dev, "power-on detected\n");
+                }
+
+                if (ds1307->regs[1] & RX8025_BIT_VDET) {
+                        ds1307->regs[1] &= ~RX8025_BIT_VDET;
+                        i2c_smbus_write_byte_data(client,
+                                                  RX8025_REG_CTRL2 << 4 | 0x08,
+                                                  ds1307->regs[1]);
+                        dev_warn(&client->dev, "voltage drop detected\n");
+                }
+
+                /* make sure we are running in 24hour mode */
+                if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
+                        u8 hour;
+
+                        /* switch to 24 hour mode */
+                        i2c_smbus_write_byte_data(client,
+                                                  RX8025_REG_CTRL1 << 4 | 0x08,
+                                                  ds1307->regs[0] |
+                                                  RX8025_BIT_2412);
+
+                        tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+                                        RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
+                        if (tmp != 2) {
+                                pr_debug("read error %d\n", tmp);
+                                err = -EIO;
+                                goto exit_free;
+                        }
+
+                        /* correct hour */
+                        hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
+                        if (hour == 12)
+                                hour = 0;
+                        if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
+                                hour += 12;
+
+                        i2c_smbus_write_byte_data(client,
+                                                  DS1307_REG_HOUR << 4 | 0x08,
+                                                  hour);
+                }
+                break;
         default:
                 break;
         }
@@ -734,6 +811,7 @@ read_rtc:
                         dev_warn(&client->dev, "SET TIME!\n");
                 }
                 break;
+        case rx_8025:
         case ds_1337:
         case ds_1339:
                 break;
@@ -747,6 +825,8 @@ read_rtc:
                  * systems that will run through year 2100.
                  */
                 break;
+        case rx_8025:
+                break;
         default:
                 if (!(tmp & DS1307_BIT_12HR))
                         break;