Hi Greg, Thankyou for the elaborative post and the link you sent.My understanding is mainly theoretical and inlined with what you wrote..
Yes,I have been scanning across many links on google and stack overflow but not able to find single one convincing. I came to conclusion that i will write a hello world gpio driver with lots of printk and build it along with the dts file by placing it in arch/arm/boot/dts and then loading that kernel image.According to R.Nelson's link i will copy the dtb files as well. Init--> probe-->register platform driver(.compatible string in the platform_device structure ) should throw something to go ahead with then. But still the loop holes in the understanding like why to copy all the dtb files,how to build only that dtb file and copy it in the lib/firmware and dynamically insmod the driver ....where does overlays come into the picture...can the drivers without dtb implementation be accepted in kernelmain line... Really looking for some example code here. On Monday 25 July 2016, Greg <[email protected] <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: > I'm not sure there is a one-stop shop for understanding the Device Tree > anywhere. > > There are at least 4 file types involved: > > 1. dts- This is the source code (text file) which is a data structure to > describe hardware. > 2. dtsi- A sub-chunk or "include" file which is used inside dts files. > It's somewhat similar to an "include" or "import" in programming languages. > 3. dtb- Device tree blob. This is the compiled version of the dts. > This is what gets loaded at boot time. It's the foundation of the system > used by the kernel. > 4. dtbo- Device tree overlay. This can be loaded after boot time. This > is how the Beaglebone adjusts itself when different "capes" are plugged > in. It does this by reading information stored in the EEPROM in the cape. > These "overlays" can also be loaded at the command line using the "slots" > in the sysfs virtual file system. Look for a substantial collection of > already done overlays in the directory /lib/firmware. If you want to make > your own overlay, /lib/firmware is where you want to place it. > > This topic is really confusing, and no doubt my notes above are full of > flaws. > > You can work through and understand all of the above. However, depending > on the complexity of what you are trying to do, this may be sufficient: > > https://github.com/cdsteinkuehler/beaglebone-universal-io > > Using the config-pin -f option and a simple text file you can use your > .profile or similar start-up configuration file to set the pins to your > requirements. > This is a relatively straight-forward solution to tacking the problem. > > In my opinion the device tree is a major hurdle to making progress with > the Beaglebones. If you google you will get a bunch of out-dated > information, so be careful what you read on the net. Perhaps someone will > suggest single source of accurate information on this topic. > > Regards, > Greg > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/cLDC6Le0Z4A/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/2a565144-1715-4bc2-ae74-b6415a30dea1%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/2a565144-1715-4bc2-ae74-b6415a30dea1%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAEwN%2BMB16im1R%2BtCPjpSk86sQ-2Lr4207yRU9Y_OrCBZfqeOEw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
