//----------------------------------------------------------------
//	engine2d.c
//
//	This character-mode Linux device-driver supports mapping
//	of the SiS 2D graphics engine registers into user space. 
//
//	NOTE: Written and tested w/ Linux kernel version 2.4.21.
//
//	programmer: ALLAN CRUSE
//	written on: 01 NOV 2003
//----------------------------------------------------------------

#define __KERNEL__
#define   MODULE

#include <linux/module.h>	// for init_module()
#include <linux/pci.h>		// for pci_find_device()

#define VGA_CLASS	0x030000
#define VENDOR_ID	0x1039
#define	SUCCESS		0

static char modname[] = "engine2d";
static int my_major = 101;
static unsigned long mm_base;
static unsigned long mm_size;
static struct pci_dev *devp = NULL;

static int my_mmap( struct file *file, struct vm_area_struct *vma )
{
	unsigned long	region_length = vma->vm_end - vma->vm_start;
	unsigned long	region_origin = vma->vm_pgoff * PAGE_SIZE;
	unsigned long	phys_address = mm_base + region_origin;
	unsigned long	virt_address = vma->vm_start;

	// sanity check: mapped region cannot extend beyond device 
	if ( region_origin + region_length > mm_size ) return -EINVAL;

	// let the kernel know not to try swapping out this region
	vma->vm_flags |= VM_RESERVED;

	// tell the kernel to exclude this region from core dumps
	vma->vm_flags |= VM_IO;

	if ( io_remap_page_range( virt_address, phys_address,
		region_length, vma->vm_page_prot ) ) return -EAGAIN;

	return	SUCCESS;
}


static struct file_operations 
my_fops =	{
		owner:		THIS_MODULE,
		mmap:		my_mmap,
		};


int init_module( void )
{
	printk( "<1>\nInstalling \'%s\' module ", modname );
	printk( "(major=%d) \n", my_major );

	devp = pci_find_class( VGA_CLASS, devp );
	if ( !devp ) return -ENODEV;
	
	mm_base = pci_resource_start( devp, 1 );
	mm_size = pci_resource_len( devp, 1 );

	printk( "<1>  %s \n", devp->name );
	printk( "  vendor=%04X  device=%04X \n", devp->vendor, devp->device );
	printk( "  base=%08X  size=%08X \n", mm_base, mm_size );
	
	if ( devp->vendor != VENDOR_ID ) return -ENODEV;

	return	register_chrdev( my_major, modname, &my_fops );
}


void cleanup_module( void )
{
	unregister_chrdev( my_major, modname );
	printk( "<1>Removing \'%s\' module\n", modname );
}

MODULE_LICENSE( "GPL" );