On Tue, Mar 08, 2005 at 12:54:14PM +0530, Dhanashri Bhate wrote:
> I am trying to write a simple interrupt driven driver for COM1 port,
> which should print whatever data arrives on the COM1 port.
>
> The problem is, my module gets loaded properly, but control doesn't go
> to the handler function. Looks like interrupt is not caught.
>
> here are some more details:
>
> version 2.4.18-14 , runlevel 3
>
> Setserial shows this info:
> /dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4, Baud_base: 115200,
> close_delay: 256, divisor: 0
> closing_wait: 15360
> Flags: spd_normal skip_test
So there already is a driver that took control of the serial port.
> In the program:
>
> Init module:
> /* enable serial port interrupts , SER_PORT=0x03f8 */
> outb( 0x01, SER_PORT+1 );
> free_irq(4, NULL);
You can't randomly free interrupts, and you're certainly not supposed
to free interrupts when you just *enabled* the interrupt source on the
device.
> request_irq(4,irq_handler,0,"serialport_irq_handler",NULL);
>
> In irq_handler:
>
> void irq_handler(int irq, void *dev_id, struct pt_regs *regs)
IRQ handlers are not void functions, but return irqreturn_t.
> {
> static unsigned char scandata;
> static struct tq_struct task =
> {
> routine:got_data,
> data:&scandata
> };
Interesting way to pass data, but wrong. The normal way is to put
device instance related data in dev_id->priv (a void*, so you can put
anything you want in it).
> scandata = inb(SER_PORT);
> printk( "<1>SerialPortDriver: in the irq_handler function\n");
> queue_task_irq(&task, &tq_immediate);
> mark_bh(IMMEDIATE_BH);
> }
>
>
> Function got_data just prints the received data.
>
> Another program that polls COM1 works fine. Could anyone please tell
> me whats wrong here?
Two drivers competing for the same piece of hardware, that's a recipe
for disaster. Remove the standard serial module and retry your own
module.
Erik
--
Erik Mouw
J.A.K.Mouw@xxxxxxxxxxxxxx mouw@xxxxxxxxxxxx
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