On Thu, Mar 15, 2001 at 09:52:46AM -0500, Craig Haller wrote:
> We are developing a parallel port device for the embedded systems
> market and need to make it fully Linux compatible. We are new to
> Linux. Can some forward an example code snippet, from which we will
> continue, that:
First of all, there are several different ways to do this. The way
you choose will ultimately depend on which version of the Linux kernel
you intend to write drivers for.
You might want to consider making the specifications available for the
device (in terms of what to send/receive and when, and what it means),
so that Linux drivers can be written for you by Linux advocates who
decide that they want to use your device.
> 1. Opens the parport driver
> 2. "Attempts" to set up ECP mode
> 3. Sends a buffer
> 4. Recieves a buffer
> 5. Closes the port
Under 2.4.x kernels, this is (supposed to be) easy to do from user
space, like this (might not compile):
#include <stdio.h>
#include <sys/ioctl.h>
#include "parport.h"
#include "ppdev.h"
int main ()
{
// No error checking..
int mode;
char *buffer;
// Open the parport driver
int fd = open ("/dev/parport0", O_RDWR);
// Attempt to set up ECP mode
mode = IEEE1284_MODE_ECP;
ioctl (fd, PPNEGOT, &mode);
buffer = malloc (20);
// Send a buffer
write (fd, buffer, 20);
// Receive a buffer
read (fd, buffer, 20);
// Close the port
close (fd);
}
Here, "parport.h" and "ppdev.h" are the files from the kernel source
tree (just put them in your source directory).
For 2.2.x kernels, the /dev/parport0 driver isn't in the mainstream
source and so you need to apply a kernel patch to make the above
program work.
Another way of doing it is to write an in-kernel driver. For this too
I'd recommend writing for 2.4.x kernels than 2.2.x kernels, since
there is better support for things like ECP transfers and IEEE 1284
negotiation.
Take a look at <URL:http://people.redhat.com/twaugh/parport/html/> for
more information about writing parport drivers for 2.4.x kernels.
Hope that helps.
Tim.
*/
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