# The OS/K Team licenses this file to you under the MIT license.
# See the LICENSE file in the project root for more information.

To communicate with devices, use:
    devctl #dev #slot
    iocall #dev #slot

This will call a function from the device's slot table.
It will take registers ax0-ax7 as its parameters, and
return a value in rdx:rax.

The return value in rax is a status value:
        ≥0          ok (>0 only if meaningful)
        -1          unspecified error
        -2          no such device
        -3          device powered off
        -4          device fatal error
        -5          device not plugged
        -6          no such function slot
        -7          slot not implemented
        -8          slot reserved
        -9          invalid parameters
    -10 to -256     (reserved)
     < -256         (left to device)

The slots for "devctl" are architecture-rerserved.
They consist of the following functions:
       Slot     Param (ax0)     Description
        0           ptr         Write device type into buffer
        1           ptr         Write device name into buffer
        2           ptr         Write device model into buffer
        3           ptr         Write device vendor into buffer
        4                       rax=major, rdx=minor
        5                       rax=feats, rdx=revis

The slots for "iocall" are device-defined. (They correspond
to the "fslots" array of the dev_t structure.) See that
particular device's documentation (if any).