linux-kernel - Re: How to access correctly serial port inside module?

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Message-ID: <465D2BEC.2090008@gmx.de>
Date:	Wed, 30 May 2007 09:46:52 +0200
From:	"Lars K.W. Gohlke" <lkwg82@....de>
To:	Tilman Schmidt <tilman@...p.cc>
CC:	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	linux-kernel@...r.kernel.org
Subject: Re: How to access correctly serial port inside module?

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Lars K.W. Gohlke schrieb:
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> Tilman Schmidt schrieb:
>> Am 24.05.2007 21:15 schrieb Lars K.W. Gohlke:
>>> Jan Engelhardt schrieb:
>> [code proposal]
>>>> [I've warned about it... ;-) ]
>>> is it the way to access from kernelspace the userspace fs?
>>> the not-correct-way?
>>
>> Yes, indeed.
>>
>>> If it is so, I will wait for another solution ;)
>>
>> I'm not sure waiting will help. The roasted pigeons will not come
>> flying into your mouth.
>>
>> The possible solutions have been sketched out for you:
>>
>> a) open the device file from the kernel (described by Jan):
>>    actively discouraged by the kernelnewbies.org FAQ document,
>>    and probably won't even work IMHO
>>
>> b) program the serial port directly (described by Jan):
>>    will work only with one type of hardware and you'll have to
>>    disable the regular serial driver first; frowned upon by kernel
>>    gurus as "reinventing the wheel"
>>
>> c) abuse the line discipline interface (described by me):
>>    moderately well documented, and there's precedent for using it
>>    that way in the well-accepted PPP module as well as my humble
>>    contribution, the ser_gigaset driver; requires a userspace
>>    daemon for pushing the line discipline module on the serial
>>    port and keeping it there
>>
>> d) use the serio interface (described by Ying Huang):
>>    potentially cleaner conceptually and seems to work without a
>>    userspace daemon, but apparently not documented anywhere
>>    except in the source files drivers/input/serio/serport.c
>>    and linux/drivers/input/mouse/sermouse.c
>>
>> Now it's your turn to decide.
>>
>> HTH
>> T.
>>
>
> When I'm chosing option d) can smb. help me step by step? There are so
> many pieces of code I don't understand.
>
> Ok, let's begin:
>
> my kernel source base is : ubuntu-lts 6.06 and 2.6.15-7
> http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.15.y.git;a=tree;f=drivers/input/serio;
>
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[linux/drivers/input/mouse/sermouse.c]

Where can I see, which serial line is used to get data stream from?

The mouse is plugged in. Where is the decision made, that maybe port0 is
  used?
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