Messages in this thread | | | Date | Thu, 18 Nov 2010 10:03:12 -0600 | From | Timur Tabi <> | Subject | Re: How do I choose an arbitrary minor number for my tty device? |
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Greg KH wrote: >> > >> > I'm still not sure why you think I have a bus. I don't see where the UART >> > drivers register a bus, and there's not a whole lot different between a byte >> > channel and a UART.
> But they are obviously two different things, right?
Well, sure. A byte channel is just a software concept. You can send data, receive data, and poll a byte channel. You can't set the baud rate, or send break signals or even do flow control. I debated making the driver act like a fake serial device, which probably would have been easier but not "correct".
Unfortunately, I seem to lack some fundamental understanding of tty drivers that is making my life difficult. I've been reading all the documentation that I can get my hands on, as well as studying a lot of source code, but I still can't find any example to base *my* code on. I just don't know if what I'm doing is right.
I still don't know how to connect the byte channel handle with the /dev entry. That's the question my original post asked, and I still don't have an answer to it.
> Why not? It sounds like there should be, right? That would make things > much easier for you in the end from what I can tell.
I'm not so sure. Like I said, I still don't see where there's a bus. I have a single driver that has multiple devices. It sounds to me like one call to tty_register_driver() and multiple calls to tty_register_device() would be sufficient.
For instance, there is no code in drivers/char/ that makes a call to bus_register(), so I don't see any precedent for a tty driver to register a bus first.
Also, this is an Open Firmware driver. I already have a mechanism whereby I get probed for each instance of a byte channel. Isn't that my "bus"?
I'm really trying to do the right thing here, Greg, but every time I try to solve one problem, I'm being told that I need to make things way more complicated first.
-- Timur Tabi Linux kernel developer at Freescale
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