rtc: rtc-ds1307 add ds3231

Add ds3231 variant.  For that, the BBSQI bit position was changed from a
simple define into a lookup-array as it differs.  This also removes
writing to an unused bit in case of the ds1337.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 4 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 52e2427e5a95..8a6f9a9f9cb8 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -32,6 +32,7 @@ enum ds_type {
         ds_1339,
         ds_1340,
         ds_1388,
+        ds_3231,
         m41t00,
         rx_8025,
         // rs5c372 too?  different address...
@@ -67,6 +68,7 @@ enum ds_type {
 #define DS1337_REG_CONTROL      0x0e
 #       define DS1337_BIT_nEOSC         0x80
 #       define DS1339_BIT_BBSQI         0x20
+#       define DS3231_BIT_BBSQW         0x40 /* same as BBSQI */
 #       define DS1337_BIT_RS2           0x10
 #       define DS1337_BIT_RS1           0x08
 #       define DS1337_BIT_INTCN         0x04
@@ -130,6 +132,9 @@ static const struct chip_desc chips[] = {
 },
 [ds_1340] = {
 },
+[ds_3231] = {
+        .alarm          = 1,
+},
 [m41t00] = {
 },
 [rx_8025] = {
@@ -142,6 +147,7 @@ static const struct i2c_device_id ds1307_id[] = {
         { "ds1339", ds_1339 },
         { "ds1388", ds_1388 },
         { "ds1340", ds_1340 },
+        { "ds3231", ds_3231 },
         { "m41t00", m41t00 },
         { "rx8025", rx_8025 },
         { }
@@ -356,6 +362,7 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
         switch (ds1307->type) {
         case ds_1337:
         case ds_1339:
+        case ds_3231:
                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
                 break;
         case ds_1340:
@@ -628,6 +635,11 @@ static int __devinit ds1307_probe(struct i2c_client *client,
         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
         int                     want_irq = false;
         unsigned char           *buf;
+        static const int        bbsqi_bitpos[] = {
+                [ds_1337] = 0,
+                [ds_1339] = DS1339_BIT_BBSQI,
+                [ds_3231] = DS3231_BIT_BBSQW,
+        };
 
         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
@@ -654,6 +666,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
         switch (ds1307->type) {
         case ds_1337:
         case ds_1339:
+        case ds_3231:
                 /* has IRQ? */
                 if (ds1307->client->irq > 0 && chip->alarm) {
                         INIT_WORK(&ds1307->work, ds1307_work);
@@ -673,12 +686,12 @@ static int __devinit ds1307_probe(struct i2c_client *client,
                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 
                 /* Using IRQ?  Disable the square wave and both alarms.
-                 * For ds1339, be sure alarms can trigger when we're
-                 * running on Vbackup (BBSQI); we assume ds1337 will
-                 * ignore that bit
+                 * For some variants, be sure alarms can trigger when we're
+                 * running on Vbackup (BBSQI/BBSQW)
                  */
                 if (want_irq) {
-                        ds1307->regs[0] |= DS1337_BIT_INTCN | DS1339_BIT_BBSQI;
+                        ds1307->regs[0] |= DS1337_BIT_INTCN
+                                        | bbsqi_bitpos[ds1307->type];
                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
                 }
 
@@ -825,6 +838,7 @@ read_rtc:
         case ds_1337:
         case ds_1339:
         case ds_1388:
+        case ds_3231:
                 break;
         }