linux-kernel - Re: [PATCH 5/8] rtc: isl12022: implement RTC_VL_READ and RTC_VL

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Date:   Tue, 13 Jun 2023 09:53:03 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/8] rtc: isl12022: implement RTC_VL_READ and RTC_VL_CLR
 ioctls

On 12/06/2023 18.10, Alexandre Belloni wrote:
> On 12/06/2023 18:48:49+0300, Andy Shevchenko wrote:
>> On Mon, Jun 12, 2023 at 01:30:55PM +0200, Rasmus Villemoes wrote:
>>> Hook up support for reading the values of the SR_LBAT85 and SR_LBAT75
>>> bits. Translate the former to "battery low", and the latter to
>>> "battery empty or not-present".
>>
>> ...
>>
>>> +static int isl12022_read_sr(struct regmap *regmap)
>>> +{
>>> +	int ret;
>>> +	u32 val;
>>> +
>>> +	ret = regmap_read(regmap, ISL12022_REG_SR, &val);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +	return val;
>>
>> Wondering if the bit 31 is in use with this register (note, I haven't checked
>> the register width nor datasheet).
>>
> 
> register width is in the driver:
> 
> static const struct regmap_config regmap_config = {
> 	.reg_bits = 8,
> 	.val_bits = 8,
> 	.use_single_write = true,
> };

Yeah.

But I only factored that out because I wanted to read the SR also in the
isl12022_set_trip_levels() to emit the warning at boot time, but when
that goes away, there's no longer any reason to not just fold this back
into the ioctl() handler.

Rasmus