read for serial driver

Mar 05, 2004 1 Replies
B

I am writing a serial driver on Linux ?2.4.18-rmk7-pxa1. I was going through the source code and I found that the device specific driver does not implemen the 'read' function. The interrupt handler of the device specific driver copies the character read in to tty->flip.char_buf_ptr and then calls 'tty_flip_buffer_push' function. I checked from the 'tty_read' function and it calles 'tty->ldisc.read' function call.



My question is, when the user calls the 'read' call on say /dev/ttyS0 from which read function the character is actually read. If someone could give me the function trace it would be great. Also, I could not find out what is this 'tty->ldisc.read' function and from where is it coming?



Any help in this area is highly appreciated.



Thanks, Bhavin


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G

It's read from the tty layer's receive buffer. That's where it goes after you put it in the flip buffer and push it.

Huh? Function trace of what? The tty I/O module's read() function?

IIRC it's a pointer. Look for places where it's set. If you're just writing a low-level serial driver, you don't need to worry about it. All you need to do is put the receive data in the flip buffer.

Grant Edwards grante Yow! ... I want a COLOR at T.V. and a VIBRATING BED!!! visi.com
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