From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric@anholt.net (Eric Anholt) Date: Fri, 20 Mar 2015 10:24:20 -0700 Subject: [PATCH 3/4 v4] mailbox: Enable BCM2835 mailbox support In-Reply-To: <550BA6B4.3030604@wwwdotorg.org> References: <1426213936-4139-1-git-send-email-eric@anholt.net> <1426213936-4139-3-git-send-email-eric@anholt.net> <5507A095.5090805@wwwdotorg.org> <87619xq414.fsf@eliezer.anholt.net> <550BA6B4.3030604@wwwdotorg.org> Message-ID: <87wq2bk2ez.fsf@eliezer.anholt.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Stephen Warren writes: > On 03/18/2015 05:28 PM, Eric Anholt wrote: >> Stephen Warren writes: >> >>> On 03/12/2015 08:32 PM, Eric Anholt wrote: >>>> diff --git a/drivers/mailbox/bcm2835-mailbox.c >>>> b/drivers/mailbox/bcm2835-mailbox.c >>> >>>> +#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & >>>> 0xf)) +#define MBOX_CHAN(msg) ((msg) & 0xf) +#define >>>> MBOX_DATA28(msg) ((msg) & ~0xf) >>> >>> Even the concept of storing channel IDs in the LSBs feels like it >>> might be RPi-firmware-specific rather than HW-specific? >> >> I guess? If we found another firmware protocol, we could have >> that device's dt just specify a different compatible string. But >> in the absence of another firmware to talk to, I'm not sure what >> you want here. > > I would expect the mailbox driver to expose a single channel that just > transports 32-bit values, since the HW doesn't impose any kind of > structure on the values it transports AFAIK. Clients of the mailbox > driver would formulate the messages they send through the mailox using > the macros above. > > I'm not sure whether the mailbox core allows multiple clients for the > same mailbox channel though? This HW appears to require it. Yeah, that's the problem. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 818 bytes Desc: not available URL: