Re: [RFC] EC registers - Adding sysfs interface?

[Alexey Starikovskiy <astarikovskiy@suse.de>]

Alexey Starikovskiy wrote:
> Carlos Corbacho wrote:
>> Alexey,
>>
>> I'm considering writing a sysfs interface for the EC registers, and 
>> was wondering if you would be ok with such a patch (before I start 
>> work on it)?
> What do you need that for?
>>
>> I'd like to expose the registers to userspace, as it is already 
>> possible to access the EC registers in userspace via /dev/ports (and 
>> quite a few of us 
> Well, this is not an argument. You have access to all memory through 
> /dev/mem, so what?
>> would like to access them) - however, the problem with doing this is 
>> that ACPI throws quite a few warnings/ errors in dmesg whilst doing 
>> this; it would therefore be far preferable to expose the registers 
>> through sysfs, which would in turn be based on the ec_{read,write} 
>> calls, so we don't end up stepping on ACPI's toes.
> I think it is better to do it in file system that allows seek(). So you 
> could do with 1 file instead of 256 of them.
>>
>> So, basically, I'm proposing something like:
>>
>> /sys/firmware/acpi/ec/ecX
>> |
>> |-> 0
>> |-> 1
>> |-> 2
>> |-> etc... (up to 255)
>>
>> Where each file returns the contents of the EC register in question 
>> (via ec_read()), and writing to the file calls ec_write().
> Carlos, I don't like the idea of 256 files. This will consume too many 
> resources and will not bring much value.
> If you want to have something permanent, it should be slim and fast.
How about character /dev/ec0?
> If we talk about some debug/research/RE, do it as you like, but don't 
> ask for submission into kernel :)
> Regards,
> Alex.
>