Re: [PATCH 2/2] uio: add an of_genirq driver

On Tue, Jun 16, 2009 at 3:04 AM, Wolfram Sang[off-list ref] wrote:

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diff --git a/Documentation/powerpc/dts-bindings/uio-generic.txt b/Docu=

mentation/powerpc/dts-bindings/uio-generic.txt

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new file mode 100644
index 0000000..8ad9861

--- /dev/null
+++ b/Documentation/powerpc/dts-bindings/uio-generic.txt

@@ -0,0 +1,16 @@
+UIO for custom devices
+
+A device which will be mapped using the UIO subsystem.
+
+Properties:
+ - compatible : should contain the specific model used, followed by
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0"generic-uio".
+ - reg : address range(s) of the device (up to MAX_UIO_MAPS)
+ - interrupts : interrupt of the device
+
+Example:
+ =A0 =A0 =A0 =A0c64fpga@0 {
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0compatible =3D "ptx,c64fpga001", "gen=

eric-uio";

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+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0reg =3D <0x0 0x10000>;
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0interrupts =3D <0 0 3>;
+ =A0 =A0 =A0 =A0};

Hmmm, I'm not happy about this. =A0The device tree describes the
hardware, not the way Linux uses the hardware. =A0UIO definitely falls
into the category of Linux implementation detail.

Yes, I am aware of that. I just started with the mechanisms which are ava=

ilable

today and hoped we could find some compatible-value which will suit all n=

eeds.

Trouble is a value that suits all needs today probably won't a year
from now.  :-)

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This should be approached from the other way around. =A0Either the
generic-uio of_platform driver should contain an explicit list of
devices to be handled by UIO,

Well, that could lead to a quite huge match_table over time.

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or the OF infrastructure should be modified to allow things like force
binding of_devices to of_drivers at runtime.

That is an interesting idea. I could imagine something like a 'new_compat=

ible"

entry in the sysfs-section of the driver similar to 'new_id' for PCI. Aft=

er

writing a new compatible-string into it, matching will triggered again wi=

th the

new entry added. That could (should?) also be placed at the of-core-level=

. Or

did you have something else in mind?

Yeah, that sounds appropriate.

g.

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.