Messages in this thread |  | | Date | Wed, 27 Sep 2000 15:23:39 -0700 | From | Mike Touloumtzis <> | Subject | Re: Russell King forks ARM Linux. |
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On Wed, Sep 27, 2000 at 02:30:13PM -0700, H. Peter Anvin wrote: > > For what it's worth, the SA1100 serial driver has been registered with > me on the Low-Density Serial Ports major (204) as /dev/ttySA0-2 (minor > 5-7). > > Russ is 100% correct that different drivers shouldn't use the > same device numbers, unless they are: > > a) mutually exclusive, > b) interface compatible, *AND* > c) handle all arbitration necessary. > > If (a), (b) and (c) are all satisfied, it is often justified to share > device numbers and device nodes.
I jumped into this discussion on linux-arm-kernel before realizing it had wandered here.
I don't see the major 204 allocation in devices.txt, so I'm not sure if this has already been covered, but it would be nice to have an allocation for "on-chip UARTs" in system-on-chip type configurations. I recently worked on a port to the Cirrus Logic EP7211, which is an ARM-based system-on-chip (CPU, UARTs, LCD controller, DRAM controller, etc.) It seems hoggish to ask for an allocation for such a non-general-purpose piece of hardware.
If we had (say) 4 or 8 on-chip UART device numbers for regular serial, plus a corresponding 4 or 8 for serial IR using the same UARTs, that would cover things nicely (EP7211 has only 2 UARTs but I figure it'll be good to leave some room). And on-chip UARTs are by definition mutually exclusive (unless you start talking about sharing /dev via NFS between heterogeneous embedded systems).
miket
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