LinuxQuestions.org - lodable kernel module doubt...

Here's the program...
// PCI driver

#define OUR_PCI_VENDER_ID 0x10b5
#define OUR_PCI_DEVICE_ID 0x9054

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <asm/system.h>
#include <asm/io.h>
#include <linux/types.h>

Quote:

struct pci_card_driver {
void *mm_addr;
struct pci_dev *ppdev;
};

static struct pci_device_id our_pci_id_tb[] = {
{ OUR_PCI_VENDER_ID, OUR_PCI_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0
},
{ 0, }
};
MODULE_DEVICE_TABLE (pci, our_pci_id_tb);

Quote:

static int init_module_probe(struct pci_dev *pdev, const struct pci_device_id *notused)
{
struct pci_card_driver *pci_ptr;
unsigned long mmio_start, mmio_end, mmio_len, mmio_flags, data, data1, data2, data3, data4, data_out, data5, k1;
int err;
u32 val;

pci_ptr = kmalloc(sizeof(*pci_ptr), GFP_KERNEL);
if (!pci_ptr)
return -ENOMEM;
memset(pci_ptr,0,sizeof(*pci_ptr));
pci_ptr ->ppdev =pdev;

err=pci_enable_device(pdev);
if(err)
{
printk(KERN_ERR "err: Cannot enable the device \n");
goto error;
}

else printk("Device enabled\n");

mmio_start = pci_resource_start(pdev, 2);
mmio_end = pci_resource_end(pdev, 2);
mmio_len = pci_resource_len(pdev, 2);
mmio_flags = pci_resource_flags(pdev, 2);

if(pci_request_regions(pdev, "pci_device"))
{
printk("Could not get PCI region\n");
err= -EBUSY;
goto err_disable;
}

pci_ptr ->mm_addr = NULL;

pci_set_drvdata(pdev,pci_ptr);

pci_ptr ->mm_addr = ioremap(mmio_start, mmio_len);

if(!(pci_ptr->mm_addr))
{
printk("Could not ioremap\n");
err= -EIO;
goto err_release_mem;
}

else
{
printk(" The ioaddr is %x \n", pci_ptr -> mm_addr);
printk(" ioaddress obtained \n");

val= readl(pci_ptr->mm_addr + 0x0000100C);
printk(" My value obtained is %u32 \n ", val);

return 0;

}

err_release_mem:
pci_release_regions(pdev);
pci_set_drvdata(pdev, NULL);
err_disable:
pci_disable_device(pdev);
error:
kfree(pci_ptr);
return err;
}

Quote:

static void __devexit remove_pci(struct pci_dev *pdev)
{
struct pci_card_driver *pci_ptr = pci_get_drvdata(pdev);
if (!pci_ptr)
{
printk("<1> sum BUG error");
BUG();
}
iounmap(pci_ptr->mm_addr);
pci_release_regions(pdev);
pci_disable_device(pdev);
pci_set_drvdata(pdev, NULL);
kfree(pci_ptr);
}

Quote:

static struct pci_driver our_pci_driver = {
.name = "pci_device",
.probe = init_module_probe,
.remove = __devexit_p(remove_pci),
.id_table = our_pci_id_tb,
};

Quote:

static int __init pci_init(void)
{
printk(KERN_INFO "pci device_init\n");
return pci_register_driver(&our_pci_driver);
}

static void __exit pci_cleanup(void)
{
printk(KERN_INFO "pci device_cleanup\n");
pci_unregister_driver(&our_pci_driver);
}

module_init(pci_init);
module_exit(pci_cleanup);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Linux device driver for PCI card");