Re: How to access correctly serial port inside module?

[Lars K.W. Gohlke]

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Lars K.W. Gohlke schrieb:
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> Tilman Schmidt schrieb:
> > Am 03.06.2007 22:28 schrieb Lars K.W. Gohlke:
> > > Tilman Schmidt schrieb:
> > > > Am 17.05.2007 08:15 schrieb huang ying:
> > > > > I think the "serio" (through drivers/input/serio/serport.c) may be a
> > > > > choice too, like that in linux/drivers/input/mouse/sermouse.c, which
> > > > > is an example to program serial port in kernel space.
> > > > Interesting. I wonder if that would have been a better choice for
> > > > the Gigaset M101 driver. It seems even to have a probe mechanism
> > > > so one could try to determine if the expected device is really
> > > > connected to the port.
> > > > Is there any documentation on this interface? I find the source a
> > > > bit hard to understand, sparsely commented as it is.
> > > how can I open ttyS1 with major=4 and minor=65?
> >
> > a) With "my" approach, ie. writing a line discipline, you open
> > /dev/ttyS1 in a user space program and then push your line discipline
> > onto it using ioctl(,TIOCSETD,).
> >
> > b) With the "serio" approach, if the probe mechanism is really what
> > I think it is, you register your probe function and wait for it to
> > be called for each active serial port, then do your thing to determine
> > whether this is a/the port you want to use.
> >
> > > Does anybody have some code to read from it the first e.g. 2bytes?
> >
> > That's not how things work in the kernel. You don't "read the first
> > <n> bytes" at will. You have to provide means to process whatever
> > data happens to arrive on the serial port, as it arrives.
> >
> > a) With a line discipline, you provide a callback function
> > ".receive_buf" which will be called by the serial driver if some
> > data has been received, and has to process that data then and there.
> > You might just stow it away in a buffer of course, provided you
> > are sure to get around to processing it later.
> >
> > b) With the "serio" interface, it seems the ".interrupt" function
> > serves the same purpose - though, as I said, I am not really
> > competent on that topic.
> >
> > HTH
> > T.
> ok because I want to handle it in kernel space I will no take option a)
>
> I will try it the way of b)
>
> anyway thx.
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I asked vojtech@xxxxxxx as one of the driver developer

this is how I did it (just prototype)

(neccessary just one folder and two files)
1. copy template linux-source/drivers/input/joystick/magellan.c
2. insert in line 90  :
	printk("%s:\"%s\"\n",__FUNCTION__, data);
3. make and insert it
4. inputattach --magellan /dev/ttyS0 &
5. date > /dev/ttyS0
6. dmesg | tail

voilÃ!

[output von dmesg]

	[27336.486980] serio: Serial port ttyS0
	[27336.487270] input: LogiCad3D Magellan / SpaceMouse as
/class/input/input6 [27336.518603] magellan_process_packet:"Mi  6 Jun
19:22:31 CEST 2007"

[/output]
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