Re: [PATCH] rtc: ds1307: Enable battery backup on RX8130

[Bastian Krause <bst@pengutronix.de>]

Hi Marek,

On 6/28/19 2:21 AM, Marek Vasut wrote:
> The battery backup can be disabled on this RTC, e.g. if populated right
> out of production. Force the battery backup bit on to enable it.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Arnaud Ebalard <arno@natisbad.org>
> Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>  drivers/rtc/rtc-ds1307.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index 1f7e8aefc1eb..4af00cac1eff 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -121,6 +121,8 @@ enum ds_type {
>  #define RX8130_REG_FLAG_AF		BIT(3)
>  #define RX8130_REG_CONTROL0		0x1e
>  #define RX8130_REG_CONTROL0_AIE		BIT(3)
> +#define RX8130_REG_CONTROL1		0x0f

I think it is surprising that RX8130_REG_CONTROL0 is defined absolute
and RX8130_REG_CONTROL1 must be used with chip offset. Having this
defined consistently would be nice.

> +#define RX8130_REG_CONTROL1_INIEN	BIT(4)
>  
>  #define MCP794XX_REG_CONTROL		0x07
>  #	define MCP794XX_BIT_ALM0_EN	0x10
> @@ -1750,6 +1752,11 @@ static int ds1307_probe(struct i2c_client *client,
>  				     DS1307_REG_HOUR << 4 | 0x08, hour);
>  		}
>  		break;
> +	case rx_8130:
> +		/* make sure that the backup battery is enabled */
> +		regmap_write(ds1307->regmap, chip->offset + RX8130_REG_CONTROL1,
> +			     RX8130_REG_CONTROL1_INIEN);
> +		break;

Quick note: if a rechargeable battery or supercap is used the CHGEN bit
must be set also.

Regards,
Bastian

>  	default:
>  		break;
>  	}
> 
> 

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