missing bone_capemgr

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missing bone_capemgr

Postby ajvbun » Sun Feb 25, 2018 10:17 am

Hello,
this is my first message on this forum and I hope somebody can help me.
I am using a beagle bone Green with ArchLinux Arm and want to use ePWM2.
I started with Arch version 4.09 and the PWM was available after echoing BB_PWM2_00A0.dtbo to /sys/devices/platform/bone_capemgr/slots. Then the PWM worked fine. To be able to install other packages (base-devel) it was required to upgrade by pacman -Syu. Now I am in version 4.15.4. As now no directory bone_capemgr exist I have no idea how to insert the kernel overlay. I tried it as uboot overlay but also no success. All I want to achieve is changing the pinmux in control module $44E10000 offset conf_gpmc_ad9 $0824 from $0027 to $0004 to connect ball T10 = P8-13 from GPIO0[23] to EHRPWM2B. First I tried it with MMap in a freepascal application, but I keep reading back $27 after writing $04. It looks like this area is protected by the kernel. Unfortunately I have no knowledge to write and try an application in kernel mode.
After half a week of trying to solve this I am out of options. I hope you can help me.
Thanks, Anthony
ajvbun
 
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Re: missing bone_capemgr

Postby summers » Sun Feb 25, 2018 2:40 pm

Hi, check out this tread - its relevant https://archlinuxarm.org/forum/viewtopic.php?f=48&t=12580 so if you check

https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Where_did_the_slots_file_go.3F

You can see that plan was to remove this from the linux kernel about 4.15 - which is where we are.

So suggested method of doing device tree overlays in via uboot.

Now BB overlays has its own patch set to uboot - but don't think its merged with mainline uboot, and so not distributed by arm arch.

But digging some more, am335x uboot has the CONFIG_OF_LIBFDT_OVERLAY=y set, this means you get the command:
$this->bbcode_second_pass_code('', 'fdt apply address')
At least I think that format - I only discovered this by browsing source code.

So in uboot load a device tree blob from /lib/firmware into memory. Then after the standard device tree is loaded and configured, you should be able to apply the overlay.

I havn't tested this yet btw ....
summers
 
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Re: missing bone_capemgr

Postby summers » Sun Mar 18, 2018 6:01 pm

OK, so now tested, check this thread:

https://archlinuxarm.org/forum/viewtopic.php?f=23&t=12635#p58004

the "ftd apply" approach in uboot works for applying device tree overlays.
summers
 
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