On Feb 4 2008 18:54, [EMAIL PROTECTED] wrote:
>
>I'm writing device driver for parallel port on Linux.
Another one?
>In initial function which is argument of module_init() in my device
>driver, I reserved I/O address region, 0x378-0x37a, with using
>request_region() and regist my charactor device driver calling
>register_chrdev().
>
>After I compile and link it. I insert this module and I can confirm
>that I obtaind the range of I/O address at /proc/ioports. But I
>cannot write data on I/O address line, It means that following check
>program shows "false".
>--- check program ---
>#include <linux/types.h>
>#include <asm/io.h>
>#include <stdio.h>
A userspace program? I thought this was about kernel device drivers.
>int main(void){
> int base = 0x378;
> char read, write;
>
> ioperm(base, 1, 1);
>
> write = 0xa;
> outb(write, base);
> read = inb(base);
> if((read & 0xf) == write){
Some parallel port chips always return 0 on inb(base), for example
the AMD K6 boards that shipped with VIA Apollo chipsets (1998). On
the other hand, a chipset as old as to carry a i386DX CPU (probably
was all Intel back then) returns the desired 0xA on inb(base).
> printf("true\n");
> }else{
> printf("false\n");
> }
> return 0;
>}
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