linux-kernel - Re: [PATCH v2 2/2] misc: Add power-efuse driver

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Date:   Tue, 8 Mar 2022 00:23:43 -0800
From:   Zev Weiss <zev@...ilderbeest.net>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>, openbmc@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH v2 2/2] misc: Add power-efuse driver

On Mon, Mar 07, 2022 at 11:07:57PM PST, Greg Kroah-Hartman wrote:
>On Mon, Mar 07, 2022 at 05:18:10PM -0800, Zev Weiss wrote:
>> +static DEVICE_ATTR(operstate, 0644, efuse_show_operstate, efuse_set_operstate);
>
>DEVICE_ATTR_RW()?
>

Ack.

>> +
>> +#define EFUSE_ERROR_ATTR(name, bit)							    \
>> +	static ssize_t efuse_show_##name(struct device *dev, struct device_attribute *attr, \
>> +					 char *buf)                                         \
>> +	{                                                                                   \
>> +		struct efuse *efuse = dev_get_drvdata(dev);                                 \
>> +		int status = efuse_update_error_flags(efuse);                               \
>> +		if (status)                                                                 \
>> +			return status;                                                      \
>> +		return sysfs_emit(buf, "%d\n", !!(efuse->error_flags.cache & bit));         \
>> +	}                                                                                   \
>> +	static DEVICE_ATTR(name, 0444, efuse_show_##name, NULL)
>
>DEVICE_ATTR_RO()?
>

Ack.

>> +EFUSE_ERROR_ATTR(under_voltage, REGULATOR_ERROR_UNDER_VOLTAGE);
>> +EFUSE_ERROR_ATTR(over_current, REGULATOR_ERROR_OVER_CURRENT);
>> +EFUSE_ERROR_ATTR(regulation_out, REGULATOR_ERROR_REGULATION_OUT);
>> +EFUSE_ERROR_ATTR(fail, REGULATOR_ERROR_FAIL);
>> +EFUSE_ERROR_ATTR(over_temp, REGULATOR_ERROR_OVER_TEMP);
>> +EFUSE_ERROR_ATTR(under_voltage_warn, REGULATOR_ERROR_UNDER_VOLTAGE_WARN);
>> +EFUSE_ERROR_ATTR(over_current_warn, REGULATOR_ERROR_OVER_CURRENT_WARN);
>> +EFUSE_ERROR_ATTR(over_voltage_warn, REGULATOR_ERROR_OVER_VOLTAGE_WARN);
>> +EFUSE_ERROR_ATTR(over_temp_warn, REGULATOR_ERROR_OVER_TEMP_WARN);
>> +
>> +static struct attribute *efuse_attrs[] = {
>> +	&dev_attr_operstate.attr,
>> +	&dev_attr_under_voltage.attr,
>> +	&dev_attr_over_current.attr,
>> +	&dev_attr_regulation_out.attr,
>> +	&dev_attr_fail.attr,
>> +	&dev_attr_over_temp.attr,
>> +	&dev_attr_under_voltage_warn.attr,
>> +	&dev_attr_over_current_warn.attr,
>> +	&dev_attr_over_voltage_warn.attr,
>> +	&dev_attr_over_temp_warn.attr,
>> +	NULL,
>> +};
>> +ATTRIBUTE_GROUPS(efuse);
>
>Shouldn't these all just be what all regulator drivers report?  Or power
>drivers?  I find it odd that this would be the first driver that would
>need to export these types of attributes.  Surely there's already a
>class for this?
>

The attributes available from the underlying regulator device don't 
include the error flags, and while they do include its state 
('operstate' here), it's a read-only attribute, and from previous 
discussions with Mark I gathered that was unlikely to change (whereas it 
being read-write is a critical part of this driver's functionality).

Given his input on the first stab at this I took a while back, I've been 
hoping to hear from Mark as to whether this looked more like something 
he'd find palatable; perhaps he could chime in on this too?  (And/or on 
the regulator API question in the cover letter.)


Thanks,
Zev