[lm-sensors] [RFC PATCH 0/2] HWMON: add in-kernel interfaces to read sensor values.

MyungJoo Ham myungjoo.ham at samsung.com
Mon Nov 14 02:31:19 CET 2011

On Sat, Nov 12, 2011 at 5:46 AM, Ben Hutchings
<bhutchings at solarflare.com> wrote:
> On Fri, 2011-11-04 at 15:50 +0900, MyungJoo Ham wrote:
>> We have been reading hwmon values (TMU, the SoC-core temperature sensor,
>> and NTC, the ambient or battery surface temperature sensor) for
>> Charger-Manager. However, because hwmon does not have in-kernel interface,
>> we have been using undesired method, including "../../../fs/*.h".
>> This patch is to provide in-kernel interface for hwmon:
>> hwmon_get_value and hwmon_set_value. In order to use these two functions,
>> the hwmon driver should provide its sysfs attributes to hwmon framework
>> as well. If the hwmon driver does not provide (by providing NULL), the users
>> of the hwmon won't be able to use hwmon_get/set_value();
>> The sysfs attribute (struct attribuyte_group *) is provided with
>> hwmon_device_register; adding the second parameter to hwmon_device_register().
>> The 2/2 patch shows the changes in device drivers due to this.
> [...]
> This is an improvement, but I don't think it is quite enough.  As I
> understand the hwmon sysfs interface, all sensor values should be
> integers.  So the in-kernel interface should also work with integers,
> not strings.
> As a first implementation you could perhaps parse the strings back to
> integers.  However in the longer term the driver API should be changed
> so that hwmon drivers fully describe their sensors to the core and the
> core takes care of exposing them through sysfs and the in-kernel API.

I agree.

I'll let it the in-kernel interfaces provide integer value although it will
simply parse strings as you've addressed until we have some other
interfaces for sysfs entries in hwmon device drivers.


> Ben.
> --
> Ben Hutchings, Staff Engineer, Solarflare
> Not speaking for my employer; that's the marketing department's job.
> They asked us to note that Solarflare product names are trademarked.

MyungJoo Ham, Ph.D.
Mobile Software Platform Lab, DMC Business, Samsung Electronics

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