rtc: ds1307: add support for MCP7941x RTCs

MCP7941x RTCs are very similar to ds1307. So add support in the ds1307 driver, as it is done in the linux kernel

Signed-off-by Soeren Moch <[email protected]>

---
Cc: Tom Rini <[email protected]>

---
  drivers/rtc/ds1307.c | 30 ++++++++++++++++++++++++------
  1 file changed, 24 insertions(+), 6 deletions(-)

drivers/rtc/ds1307.c +24 -6

index 03ab1a8..20da43a 100644
@@ -10,6 +10,10 @@
  /*
   * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
   * DS1307 and DS1338/9 Real Time Clock (RTC).
+ * i2c address 0x68
+ *
+ * Date & Time support (no alarms) for MCP7941x  Real Time Clock (RTC).
+ * i2c address 0x6f
   *
   * based on ds1337.c
   */

@@ -52,12 +56,24 @@
  #define RTC_CTL_REG_ADDR	0x07
 
  #define RTC_SEC_BIT_CH		0x80	/* Clock Halt (in Register 0)   */
+#define RTC_SEC_CH		0x80	/* Clock Halt (in Register 0)   */
+
+#define RTC_DAY_VBATEN		0x00	/* Battery EN (in Register 3)   */
 
  #define RTC_CTL_BIT_RS0		0x01	/* Rate select 0                */
  #define RTC_CTL_BIT_RS1		0x02	/* Rate select 1                */
  #define RTC_CTL_BIT_SQWE	0x10	/* Square Wave Enable           */
  #define RTC_CTL_BIT_OUT		0x80	/* Output Control               */
 
+#if CONFIG_SYS_I2C_RTC_ADDR == 0x6f
+#undef RTC_SEC_CH
+#undef RTC_DAY_VBATEN
+#undef RTC_CTL_BIT_SQWE
+#define RTC_SEC_CH		0x00	/* Clock Halt (in Register 0)   */
+#define RTC_DAY_VBATEN		0x08	/* Battery EN (in Register 3)   */
+#define RTC_CTL_BIT_SQWE	0x40	/* Square Wave Enable           */
+#endif
+
  static uchar rtc_read (uchar reg);
  static void rtc_write (uchar reg, uchar val);
 

@@ -81,11 +97,11 @@ int rtc_get (struct rtc_time *tmp)
  		"hr: %02x min: %02x sec: %02x\n",
  		year, mon, mday, wday, hour, min, sec);
 
-	if (sec & RTC_SEC_BIT_CH) {
+	if ((sec & RTC_SEC_BIT_CH) == RTC_SEC_CH) {
  		printf ("### Warning: RTC oscillator has stopped\n");
-		/* clear the CH flag */
+		/* start clock */
  		rtc_write (RTC_SEC_REG_ADDR,
-			   rtc_read (RTC_SEC_REG_ADDR) & ~RTC_SEC_BIT_CH);
+			   rtc_read (RTC_SEC_REG_ADDR) ^ RTC_SEC_BIT_CH);
  		rel = -1;
  	}
 

@@ -112,6 +128,9 @@ int rtc_get (struct rtc_time *tmp)
   */
  int rtc_set (struct rtc_time *tmp)
  {
+	uchar clk_en = RTC_SEC_BIT_CH & ~RTC_SEC_CH;
+	uchar bat_en = RTC_DAY_VBATEN;
+
  	DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
  		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
  		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);

@@ -121,11 +140,11 @@ int rtc_set (struct rtc_time *tmp)
 
  	rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
  	rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
-	rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
+	rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1) | bat_en);
  	rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
  	rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
  	rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
-	rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
+	rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec) | clk_en);
 
  	return 0;
  }

@@ -142,7 +161,6 @@ void rtc_reset (void)
  {
  	struct rtc_time tmp;
 
-	rtc_write (RTC_SEC_REG_ADDR, 0x00);	/* clearing Clock Halt	*/
  	rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_SQWE | RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS0);
 
  	tmp.tm_year = 1970;