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

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Message-ID: <4655E463.7000201@gmx.de>
Date:	Thu, 24 May 2007 21:15:47 +0200
From:	"Lars K.W. Gohlke" <lkwg82@....de>
To:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
CC:	Tilman Schmidt <tilman@...p.cc>, linux-kernel@...r.kernel.org
Subject: Re: How to access correctly serial port inside module?

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Jan Engelhardt schrieb:
> On May 24 2007 19:19, Lars K.W. Gohlke wrote:
>> I want to read from serial port (I mean the port, which is called
>> /dev/ttyS0 in user-space). Then I want copy_to_user() it through
>> /proc/serialPort
>>
>> This is just to get familiar with driver programming (in kernelspace),
>> it could be better done in userspace - I know. But this is for learning.
>>
>> It is a kind of synthetic problem, but after this, I hope too know how
>> to handle further ones.
>>
>> Understood? It is a little bit strange, but hope it is explained well. ;)
>>
>> If tell me that for /dev/ttyS0 I can adept it to /dev/ttyS1 etc..
>
>
> struct file *filp = filp_open("/dev/ttyS0");
> char buf[4096];
> mm_segment_t oldfs = get_fs();
> loff_t pos = 0;
>
> set_ds(KERNEL_DS);
> while (vfs_read(filp, buf, sizeof(buf), &pos) > 0)
> 	printk("%s\n", buf);
>
> filp_close(filp);
>
>
>
> [I've warned about it... ;-) ]
>
> 	Jan
is it the way to access from kernelspace the userspace fs?
the not-correct-way?

If it is so, I will wait for another solution ;)

Dont want to learn writing nasty kernel code. *g*

Anyway thx.
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