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>Module Wrapper</H1
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> Finally we add in the usual module wrapping and the driver is done.
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> #ifndef MODULE
static int io = 0x300;
#else
static int io = -1;
MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("A driver for an imaginary radio card.");
MODULE_PARM(io, "i");
MODULE_PARM_DESC(io, "I/O address of the card.");
EXPORT_NO_SYMBOLS;
int init_module(void)
{
if(io==-1)
{
printk(KERN_ERR
"You must set an I/O address with io=0x???\n");
return -EINVAL;
}
return myradio_init(NULL);
}
void cleanup_module(void)
{
video_unregister_device(&my_radio);
release_region(io, MY_IO_SIZE);
}
#endif
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> In this example we set the IO base by default if the driver is compiled into
the kernel where you cannot pass a parameter. For the module we require the
user sets the parameter. We set io to a nonsense port (-1) so that we can
tell if the user supplied an io parameter or not.
</P
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> We use MODULE_ defines to give an author for the card driver and a
description. We also use them to declare that io is an integer and it is the
address of the card.
</P
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> The clean-up routine unregisters the video_device we registered, and frees
up the I/O space. Note that the unregister takes the actual video_device
structure as its argument. Unlike the file operations structure which can be
shared by all instances of a device a video_device structure as an actual
instance of the device. If you are registering multiple radio devices you
need to fill in one structure per device (most likely by setting up a
template and copying it to each of the actual device structures).
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