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SubjectRe: [PATCH] rtc: ds1307: check for oscillator fault on ds1388
Hi,

On 07/11/2019 14:12:45+1300, Chris Packham wrote:
> Ensure that the oscillator is running and check the OSF bit for the
> ds1388 variant. The FLAG and CONTROL registers are at a different
> location to the other supported RTCs so this requires an extra case in
> the existing switch statement.
>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
> drivers/rtc/rtc-ds1307.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index 1f7e8aefc1eb..865c06347d0a 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -101,6 +101,10 @@ enum ds_type {
> # define DS1337_BIT_A2I 0x02
> # define DS1337_BIT_A1I 0x01
> #define DS1339_REG_ALARM1_SECS 0x07
> +#define DS1388_REG_FLAG 0x0b
> +# define DS1388_BIT_OSF 0x80
> +#define DS1388_REG_CONTROL 0x0c
> +# define DS1388_BIT_nEOSC 0x80
>
> #define DS13XX_TRICKLE_CHARGER_MAGIC 0xa0
>
> @@ -1688,6 +1692,26 @@ static int ds1307_probe(struct i2c_client *client,
> }
> break;
>
> + case ds_1388:
> + err = regmap_bulk_read(ds1307->regmap, DS1388_REG_FLAG,
> + regs, 2);
> + if (err) {
> + dev_dbg(ds1307->dev, "read error %d\n", err);
> + goto exit;
> + }
> +
> + if (regs[1] & DS1388_BIT_nEOSC) {
> + regmap_write(ds1307->regmap, DS1388_REG_CONTROL,
> + regs[1] & ~DS1388_BIT_nEOSC);
> + }
> +
> + if (regs[0] & DS1388_BIT_OSF) {
> + regmap_write(ds1307->regmap, DS1388_REG_FLAG,
> + regs[0] & ~DS1388_BIT_OSF);
> + dev_warn(ds1307->dev, "SET TIME!\n");

This is not the correct way to handle that. This information is valuable
in .read_time where you should return -EINVAL when the time is know to
be invalid. Then the bit can be reset in .set_time.


--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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