[U-Boot] 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 <smoch@web.de>
---
Cc: Tom Rini <trini@ti.com>
---
 drivers/rtc/ds1307.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

> 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 <smoch@web.de>
> ---
> Cc: Tom Rini <trini@ti.com>


Tom,

since the merge window is open now, can you pick up this patch?
Or do you think this should go through some other tree?

Thanks,
Soeren


> ---
>   drivers/rtc/ds1307.c | 30 ++++++++++++++++++++++++------
>   1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/rtc/ds1307.c b/drivers/rtc/ds1307.c
> index 03ab1a8..20da43a 100644
> --- a/drivers/rtc/ds1307.c
> +++ b/drivers/rtc/ds1307.c
> @@ -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;