[patch 0/7] dt: dtb version: add version info to dtb

[Frank Rowand]

Rob,

Can this be added to the next trees to get some test exposure before submitting
to Linus?

There is currently no way to tie a device tree blob (DTB) back to the source
and environment used to create it.  Add this information, including a DTB
version number, which is somewhat analogous to the Linux kernel version number.

The DTB version number is independent of the kernel version number, and is
incremented for each make of one or more DTBs.

The DTB information is placed in node /chosen/dtb-info.  The data for this
node will be automatically generated by the .dtb make system for any .dts
that includes arch/arm/boot/dts/skeleton.dtsi, either directly or indirectly.
This means that architectures other than arm will not receive this feature.
This can be added to other architectures by modifying their skeleton.dtsi.

There are 70 of the 557 arm .dts files that do not include skeleton.dtsi.
Thus the .dtb files created for these systems will not have the
/chosen/dtb-info node:

   armada-xp-axpwifiap.dts
   armada-xp-db.dts
   armada-xp-gp.dts
   armada-xp-lenovo-ix4-300d.dts
   armada-xp-matrix.dts
   armada-xp-netgear-rn2120.dts
   armada-xp-openblocks-ax3-4.dts
   armada-xp-synology-ds414.dts
   atlas6-evb.dts
   atlas7-evb.dts
   axm5516-amarillo.dts
   bcm2835-rpi-b-plus.dts
   bcm2835-rpi-b.dts
   ea3250.dts
   ecx-2000.dts
   highbank.dts
   hip04-d01.dts
   integratorap.dts
   integratorcp.dts
   ls1021a-qds.dts
   ls1021a-twr.dts
   meson6-atv1200.dts
   moxart-uc7112lx.dts
   mt8127-moose.dts
   mt8135-evbp1.dts
   nspire-clp.dts
   nspire-cx.dts
   nspire-tp.dts
   phy3250.dts
   picoxcell-pc7302-pc3x2.dts
   picoxcell-pc7302-pc3x3.dts
   prima2-evb.dts
   r7s72100-genmai.dts
   r8a73a4-ape6evm-reference.dts
   r8a73a4-ape6evm.dts
   r8a7790-lager.dts
   r8a7791-henninger.dts
   r8a7791-koelsch.dts
   r8a7794-alt.dts
   spear1310-evb.dts
   spear1340-evb.dts
   spear300-evb.dts
   spear310-evb.dts
   spear320-evb.dts
   spear320-hmi.dts
   spear600-evb.dts
   stih407-b2120.dts
   stih410-b2120.dts
   stih415-b2000.dts
   stih415-b2020.dts
   stih416-b2000.dts
   stih416-b2020.dts
   stih416-b2020e.dts
   stih418-b2199.dts
   sun9i-a80-optimus.dts
   vexpress-v2p-ca15-tc1.dts
   vexpress-v2p-ca15_a7.dts
   vexpress-v2p-ca5s.dts
   vexpress-v2p-ca9.dts
   vt8500-bv07.dts
   wm8505-ref.dts
   wm8650-mid.dts
   wm8750-apc8750.dts
   wm8850-w70v2.dts
   xenvm-4.2.dts
   zynq-parallella.dts
   zynq-zc702.dts
   zynq-zc706.dts
   zynq-zed.dts
   zynq-zybo.dts



An example of the DTB information reported is:

  $ echo ; cat /proc/version; echo ; echo ; dmesg | grep DTB

  Linux version 4.0.0-rc4-dirty (frank at buildhost) (gcc version 4.6.x-google 20120106 (prerelease) (GCC) ) #5 SMP PREEMPT Wed Mar 18 20:04:48 PDT 2015


  DTB version 4.0.0-rc4-dirty (frank at buildhost) (DTC 1.4.0-dirty) #4 Wed Mar 18 20:04:11 PDT 2015
  DTB linux version 4.0.0-rc4-dirty (frank at build_host) (gcc version 4.6.x-google 20120106 (prerelease) (GCC) ) #3 SMP PREEMPT Wed Mar 18 20:02:46 PDT 2015
  DTB source /local/nobackup/src/git_linus/linux--4.0/arch/arm/boot/dts/qcom-apq8074-dragonboard.dts
  DTB blob arch/arm/boot/dts/qcom-apq8074-dragonboard.dtb


The values of the /chosen/dtb-info/ properties are also available in
/proc/device-tree/chosen/dtb-info/