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Device Driver Skeleton?



angelo wrote:



On Fri Feb 11 10:00:51 PST 2005, =?iso-8859-1?Q?Alex?= <kbyte@iol.pt> wrote:



Good Morning Dr Fraietta,


Not Dr yet.

At some days ago, I had a doubt concerning writing my first device driver and you said to me to send you an email on the 10th feb. So here I am... Could you help me, please?


OK

I already study the console and serial drivers in the rtems distribution and appart from the skeletton of a generic rtems device driver, why do we have to define always a macro like this:

 #define CONSOLE_DRIVER_TABLE_ENTRY \
  { console_initialize, console_open, console_close, \
    console_read, console_write, console_control }


Who invoke those functions members, and in what circunstancies?

This is my understanding of what happens. Hopefully, someone will correct me if I am wrong.
The initisalise function,

console_initialize in this case, is called when the device drivers are initialised.
The Open is when you a file open on this device, the close when you do a file close, the read when do do a read from the file, the write, when you do a write to the file, and I am not sure what the control does.

I have only implemented the initialise because I write to my device direct. I have not implemented a read, or write -- I don't treat my device like a file.  I suppose that that is what you have to decide first--whether you want to treat your device like a file or whether you want to write directly from your application



Which are the steps to put to work a device driver made by us, or, using the hello world sample how can we put a device driver to work?


I would have a look at an example that uses a COMM port (TTYS1) if you want to open and close your device like a file.

--
Angelo Fraietta

PO Box 859
Hamilton NSW 2303

Home Page


http://www.users.bigpond.com/angelo_f/

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