On 2/15/06, Srinivas G. <srinivasg@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Dear All,
>
> I am practicing the Chapter-9, Interrupt Handling of the Linux Device
> Drivers 2nd Edition book.
>
> As mentioned in the book, I prepared the parallel port to generate the
> interrupt by inserting a piece of wire into 9 and 10 pins.
>
> I was registered the interrupt during the module initialization.
>
> In the dev_write() function (which is called when application issues
> write call), I am simply writing 0xFF value to the Data Port using
> simple outb() function.
>
> My intention here is to enable the most significant bit of the Data
> Port, so that this will result in voltage difference to generate the
> interrupt.
>
> But the Interrupt Handler is not getting invoked when I issue write call
> in the application.
>
> The point here is that when I insert just one end of the wire in the
> 10th pin and the other is given a metallic contact, my Interrupt Handler
> gets invoked because of the voltage difference.
>
> Can any one provide a pointer for this situation about Interrupt Handler
> being not called even though, I enabled MSB of Data Port by writing 0xFF
> to it.
I am not sure, but I think you need to clear the MSB of data port
first and then set it. I think transision from 0 to 1 on this MSB
generates the interrupt. You are just setting 1 and 1 every time, due
to which transition is not there.
-Gaurav
>
> Here is the sample code:
> ------------------------
>
> #define HW_LEN 80
> #define IRQ_7 7
>
> #define SPP_IOBASE 0x378
> #define SPP_NR_PORTS 0x8
> #define SPP_INT_ENABLE 0x10
> #define SPP_DATA_PORT SPP_IOBASE + 0
> #define SPP_STATUS_PORT SPP_IOBASE + 1
> #define SPP_CONTROL_PORT SPP_IOBASE + 2
>
> static struct file_operations mydev_ops =
> {
> read:mydev_read,
> write:mydev_write,
> open:mydev_open,
> release:mydev_close,
> };
>
> wait_queue_head_t mywq;
>
> static int mydev_open(struct inode *inode, struct file * file) {
> MOD_INC_USE_COUNT;
> printk("<1>" "device opened\n");
> return 0;
> }
>
>
> static ssize_t mydev_read(struct file *file, char * buf,
> size_t count, loff_t * offset)
> {
> printk("<1>" "read invoked\n");
> }
>
> /***********************************************************************
> ****
> * Name:mydev_write
> * Description:
> ************************************************************************
> ***/
> static int mydev_write(struct file * file, const char * buf,
> size_t count,loff_t * offset)
> {
> printk ("%s called ...\n", __FUNCTION__);
> outb(0xFF,SPP_DATA_PORT);
> wake_up_interruptible(&mywq);
> }
>
> /***********************************************************************
> ****
> * Name:myIntHandler
> * Description:
> ************************************************************************
> ***/
> void myIntHandler(int irq, void *dev_id, struct pt_regs *regs) {
> printk ("%s invoked ...\n", __FUNCTION__);
> }
>
> static int __init init_myKeyDev(void)
> {
> int rv;
>
> rv = check_region(SPP_IOBASE, SPP_NR_PORTS);
> if (rv)
> {
> printk(KERN_INFO "can't get I/O port address 0x%lx\n",SPP_IOBASE);
> return rv;
> }
> request_region(SPP_IOBASE, SPP_NR_PORTS, TEST_DEV);
>
> init_waitqueue_head(&mywq);
>
> rv = register_chrdev(MYDEV_MAJOR_NUM, MYDEV_NAME, &mydev_ops);
> if(rv<0)
> {
> printk("<1>" "Registration Error %d\n",rv);
> return rv;
> }
> else
> {
> printk("<1>" "Registration success %d\n",rv);
> }
>
> /*** Register interrupt handler ***/
> rv = request_irq(IRQ_7, myIntHandler, SA_INTERRUPT, TEST_DEV,NULL);
> if(rv)
> {
> printk("<1>Can't get interrupt %d\n",IRQ_7);
> }
> /*** Enable parallel port interrupt reporting ***/
> outb(SPP_INT_ENABLE, SPP_CONTROL_PORT);
>
> printk("<1>%s %s initialized\n",MODULE_NAME, MODULE_VERSION);
> return 0;
> }
>
> static void __exit cleanup_myKeyDev(void)
> {
> /*** disable parallel port interrupt reporting ***/
> outb(0x00, SPP_CONTROL_PORT);
>
> /*** Free the ioports ***/
> release_region(SPP_IOBASE,SPP_NR_PORTS);
>
> /*** Free the interrupt ***/
> free_irq(IRQ_7,NULL);
>
> unregister_chrdev(MYDEV_MAJOR_NUM, MYDEV_NAME);
> printk("<1>%s %s removed\n",MODULE_NAME, MODULE_VERSION);
> }
>
> module_init(init_myKeyDev);
> module_exit(cleanup_myKeyDev);
>
> EXPORT_NO_SYMBOLS;
>
> Thanks and Regards.
> Srinivas G
>
>
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