rtc: ds1307: add support for m41t11

add m41t11 support in ds1307 driver. changes:

- add compatible string for m41t11
- check if RTC clock is running, if not
  enable the clock

Signed-off-by: Heiko Schocher <hs@denx.de>

diff --git a/drivers/rtc/ds1307.c b/drivers/rtc/ds1307.c
index 48220b4..a33f475 100644 (file)
--- a/drivers/rtc/ds1307.c
+++ b/drivers/rtc/ds1307.c
@@ -23,6 +23,7 @@ enum ds_type {
        ds_1307,
        ds_1337,
        ds_1340,
+       m41t11,
        mcp794xx,
 };
 
@@ -260,6 +261,18 @@ read_rtc:
                }
        }
 
+       if (type == m41t11) {
+               /* clock halted?  turn it on, so clock can tick. */
+               if (buf[RTC_SEC_REG_ADDR] & RTC_SEC_BIT_CH) {
+                       buf[RTC_SEC_REG_ADDR] &= ~RTC_SEC_BIT_CH;
+                       dm_i2c_reg_write(dev, RTC_SEC_REG_ADDR,
+                                        MCP7941X_BIT_ST);
+                       dm_i2c_reg_write(dev, RTC_SEC_REG_ADDR,
+                                        buf[RTC_SEC_REG_ADDR]);
+                       goto read_rtc;
+               }
+       }
+
        if (type == mcp794xx) {
                /* make sure that the backup battery is enabled */
                if (!(buf[RTC_DAY_REG_ADDR] & MCP7941X_BIT_VBATEN)) {
@@ -332,6 +345,7 @@ static const struct udevice_id ds1307_rtc_ids[] = {
        { .compatible = "dallas,ds1337", .data = ds_1337 },
        { .compatible = "dallas,ds1340", .data = ds_1340 },
        { .compatible = "microchip,mcp7941x", .data = mcp794xx },
+       { .compatible = "st,m41t11", .data = m41t11 },
        { }
 };