Query about include/linux/mailbox.h
Craig McGeachie
slapdau at yahoo.com.au
Sat Aug 31 00:57:40 EDT 2013
Hello,
At the end of all this, my question is should I put the BCM2835 mailbox
driver in drivers somewhere, and try to make use of
include/linux/mailbox.h, or should go with the view that mailbox drivers
are inherently machine specific, have no common driver framework, and
belongs in arch/arm/mach-bcm2835?
The background to this is that I'm trying to help bring Raspberry Pi
support into the mainline kernel. Lubomir Rintel coded a mailbox driver
[1] that I liked the look off and want to fix up and push upstream.
Stephen Warren suggested that Lubmir's patch had the benefit of using a
new mailbox sub-system [2] and that I should have a look at that.
I've looked at include/linux/mailbox.h, and it only has 3 function
declarations, which are all specific to the PL320. Unless there is
something I've missed, then there is no mailbox sub-system to speak of.
Just a header file that will quickly a dependency nightmare.
I found a patch submission series from Jassi Brar [3] that looks like
the start of an actual mailbox framework, but there is no indication of
it in the current kernel source. I assume it was dropped for some reason.
I don't see much benefit to a mailbox sub-system. The BCM2835 one is
quite a small piece of code, and I really see it as a machine-specific
layer for other device drivers that implement a standard sub-system
interface, like framebuffers.
Which all leads back to my opening question - which way do I jump? What
I'd prefer to do is submit arch/arm/mach-bcm2835.c etc, and maybe even a
patch to move include/linux/mailbox.h somewhere less inviting.
Cheers,
Craig.
[1]
http://lists.infradead.org/pipermail/linux-rpi-kernel/2013-April/000528.html
[2]
http://lists.infradead.org/pipermail/linux-rpi-kernel/2013-May/000546.html
[3] http://lkml.indiana.edu/hypermail/linux/kernel/1305.0/01978.html
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