how to get or initialize clock in L4Linux
martin.schroeder at openlimit.com
Fri Aug 8 15:53:22 CEST 2014
Am 08.08.2014 um 12:33 schrieb Yunchuan Geng:
> Hi Martin,
> Thanks for the response.
> First I do not know how to do it from U-Boot.
in U-Boot you can write to registers by the mw command. A sequence of
them in the bootcmd can do the clock setup. Or you add i2c support to
U-Boot and it will do the initialisation for you. This works at least
for ethernet on my board.
> But I found it might
> better to do it in mach_setup.c where l4x_arm_devices_init() is called.
Of course you can do it from within l4linux but you need to expose the
registers of the Clock Generator Block to l4linux. The main drawback of
this solution is that this l4linux task can now modify the clocking of
every other HW device even if it is caged in another l4-task.
> However, I checked the implementation of native linux, it use Device
> Tree Blob to feed initialize process with data. It would be great if I
> could load dtb into L4Linux too. Otherwise, a lot of modification job
> are needed.
> I noticed in this tread, you have asked a question about dtb, and Adam
> give a answer.
> Did you get success?
Not yet. I noticed that feature was introduced first in the latest
snapshot so I am still busy upgrading my workspace.
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