rtc: add initial support for mcp7941x parts
Add initial support for the microchip mcp7941x series of real time clocks.
The mcp7941x series is generally compatible with the ds1307 and ds1337 rtc
devices from dallas semiconductor. minor differences include a backup
battery enable bit, and the polarity of the oscillator enable bit.
Signed-off-by: David Anders <danders.dev@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index b2005b4..62b0763 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -34,6 +34,7 @@
ds_1388,
ds_3231,
m41t00,
+ mcp7941x,
rx_8025,
// rs5c372 too? different address...
};
@@ -43,6 +44,7 @@
#define DS1307_REG_SECS 0x00 /* 00-59 */
# define DS1307_BIT_CH 0x80
# define DS1340_BIT_nEOSC 0x80
+# define MCP7941X_BIT_ST 0x80
#define DS1307_REG_MIN 0x01 /* 00-59 */
#define DS1307_REG_HOUR 0x02 /* 00-23, or 1-12{am,pm} */
# define DS1307_BIT_12HR 0x40 /* in REG_HOUR */
@@ -50,6 +52,7 @@
# define DS1340_BIT_CENTURY_EN 0x80 /* in REG_HOUR */
# define DS1340_BIT_CENTURY 0x40 /* in REG_HOUR */
#define DS1307_REG_WDAY 0x03 /* 01-07 */
+# define MCP7941X_BIT_VBATEN 0x08
#define DS1307_REG_MDAY 0x04 /* 01-31 */
#define DS1307_REG_MONTH 0x05 /* 01-12 */
# define DS1337_BIT_CENTURY 0x80 /* in REG_MONTH */
@@ -137,6 +140,8 @@
},
[m41t00] = {
},
+[mcp7941x] = {
+},
[rx_8025] = {
}, };
@@ -149,6 +154,7 @@
{ "ds1340", ds_1340 },
{ "ds3231", ds_3231 },
{ "m41t00", m41t00 },
+ { "mcp7941x", mcp7941x },
{ "pt7c4338", ds_1307 },
{ "rx8025", rx_8025 },
{ }
@@ -365,6 +371,10 @@
buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
| DS1340_BIT_CENTURY;
break;
+ case mcp7941x:
+ buf[DS1307_REG_SECS] |= MCP7941X_BIT_ST;
+ buf[DS1307_REG_WDAY] |= MCP7941X_BIT_VBATEN;
+ break;
default:
break;
}
@@ -809,6 +819,23 @@
dev_warn(&client->dev, "SET TIME!\n");
}
break;
+ case mcp7941x:
+ /* make sure that the backup battery is enabled */
+ if (!(ds1307->regs[DS1307_REG_WDAY] & MCP7941X_BIT_VBATEN)) {
+ i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
+ ds1307->regs[DS1307_REG_WDAY]
+ | MCP7941X_BIT_VBATEN);
+ }
+
+ /* clock halted? turn it on, so clock can tick. */
+ if (!(tmp & MCP7941X_BIT_ST)) {
+ i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
+ MCP7941X_BIT_ST);
+ dev_warn(&client->dev, "SET TIME!\n");
+ goto read_rtc;
+ }
+
+ break;
case rx_8025:
case ds_1337:
case ds_1339: