On Monday 23 July 2007 04:47:16 pm Ken MacLeod wrote:
> We manufacture an x86 system with a device on an I/O port. We
> initially wrote our Linux driver to load in an init script and if it
> probed OK then we knew the device was present. We now want to be a
> little safer and portable by enumerating and autoloading properly.
>
> Problem is, everything I've read so far is geared towards installing
> ACPI or using it, particularly only with well-known devices for power
> management.
>
> I can't seem to find an example DSDT definition for a generic device
> or how I would tie that to its driver -- a new device developer's
> HOWTO.
Here's sample DSDT code for a UART:
Device (U000)
{
Name (_HID, EisaId ("PNP0501"))
Name (_UID, 0x40000010)
Method (_STA, 0, NotSerialized)
{
Return (0x0000000F)
}
Name (_CRS, ResourceTemplate ()
{
QWordMemory (ResourceConsumer, PosDecode, MinFixed, MaxFixed, NonCacheable, ReadWrite,
0x0000000000000000, // Address Space Granularity
0x00000FFC300E4000, // Address Range Minimum
0x00000FFC300E4007, // Address Range Maximum
0x0000000000000000, // Address Translation Offset
0x0000000000000008, // Address Length
,,, AddressRangeMemory, TypeStatic)
Interrupt (ResourceConsumer, Level, ActiveLow, Shared, ,,)
{
0x00000017,
}
})
}
The Linux driver that claims this device is drivers/serial/8250_pnp.c.
It has a pnp_dev_table[] that contains PNP IDs that it will claim.
So you need to get yourself a new unique PNP ID. I've never done it,
but you might be able to do it here:
http://www.microsoft.com/whdc/system/pnppwr/pnp/pnpid.mspx
Then add a description of your device to your DSDT using your new
PNP ID as the _HID, and write a Linux driver that registers with that
same PNP ID.
I think there's now some mechanism for autoloading using udev, maybe
using acpi_device_uevent(), but I don't know much about it.
Bjorn
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