Date: Sun, 3 Feb 2013 10:22:13 -0800 From: Tim Kientzle <tim@kientzle.com> To: Iain Young <iain@g7iii.net> Cc: freebsd-arm@freebsd.org, Ian Lepore <ian@freebsd.org> Subject: Re: Beaglebone Serial Ports Message-ID: <2D47C68A-2891-48C5-805C-7A0438EF31D4@kientzle.com> In-Reply-To: <510E5954.7000303@g7iii.net> References: <510CE8E0.9070102@g7iii.net> <1359818003.93359.381.camel@revolution.hippie.lan> <66029B5F-2A19-4683-B589-814932E156A2@kientzle.com> <510E5954.7000303@g7iii.net>
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On Feb 3, 2013, at 4:34 AM, Iain Young wrote: > On 02/02/13 20:03, Tim Kientzle wrote: >>=20 >> On Feb 2, 2013, at 7:13 AM, Ian Lepore wrote: >>=20 >>> On Sat, 2013-02-02 at 10:22 +0000, Iain Young wrote: >>>> Hi Folks, >>>>=20 >=20 >> It should just be a matter of updating the DTS file with >> additional UART entries and updated pinmux. >>=20 >> Unfortunately, the current BeagleBone builds use a compiled-in >> device tree, so you'll have to edit the DTS file at >> sys/boot/fdt/dts/beaglebone.dts >> and then rebuild the kernel. >=20 > Thanks both, you gave me the exact hints to go look in the right > place. >=20 > I already have a partial patch written, after I found the register > addresses and interrupts in a linux dmesg output :) The Linux DTS is a useful reference as well. > Is it appropriate to post small(ish) patches here ? Of course. As far as possible, I would like for the DTS to include as much detail as possible about the board and it's facilities -- even if the driver support isn't yet complete -- and look for other ways of enabling/disabling those facilities at runtime. (Other than editing the DTS file.) > It'll probably be next weekend before I get the chance to test it, > as it seems I am lacking dtc, so need to buildworld (according to > the great google...), but the 8 Gig card isn't due here for a few > days. >=20 > Tim, I've already grabbed your 8G image with the fixed cpsw > driver, so I will test that at the same time. >=20 >> I'd like to move that out of the kernel; the loader already >> has logic to load a DTS file and pass it to the kernel, >> it should just need some tinkering with loader.rc to get >> it working. That would make it a lot easier to tweak >> settings on a per-system basis without having to rebuild >> the kernel. >>=20 >>> According to the datasheet all the onboard uarts should be supported = by >>> our standard uart driver (but only uart1 has all the modem-control = lines >>> wired). >=20 > Only by default. We just need to set the pinmux appropriately to gain > access to CTS and RTS for UARTS 1 thru 5. UART3 only has CTS and RTS > exposed, no TX or RX, but then that still has it's uses for things > like PPS and testing MSF receivers prior to looking at GPIO interrupts > :) >=20 > = http://www.jerome-bernard.com/blog/2012/06/04/beaglebone-serial-ports-and-= xbees/ has a list of which serial ports are mapped to which pins, > and the pinmux mode they need in order to access them. The definitive references are: * TI document sprs717e.pdf is the data sheet for the processors with = full pinout information, including pinmux settings. You'll need to know = that the BeagleBone uses the 'ZCZ' package (different packages have = slightly different pinouts). For TI documents, the last letter is the = revision (I have sprs717d here); they update them every couple of = months. http://www.ti.com/lit/ds/sprs717e/sprs717e.pdf * BeagleBone SRM includes schematics for the board and pinouts for the = expansion headers. = http://beagleboard.org/static/beaglebone/latest/Docs/Hardware/BONE_SRM.pdf= * TI document spruh73g.pdf is the Technical Reference Manual for the = SoC. 4500 pages documenting every subsystem; guaranteed to help with = your insomnia. ;-) http://www.ti.com/lit/ug/spruh73g/spruh73g.pdf
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