Revert "dt: add documentation of ARM dt boot interface"

This reverts commit 9830fcd6.

The ARM dt support has not been merged yet; this documentation update
was premature.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Documentation/arm/Booting

@@ -65,19 +65,13 @@ looks at the connected hardware is beyond the scope of this document.
 The boot loader must ultimately be able to provide a MACH_TYPE_xxx
 value to the kernel. (see linux/arch/arm/tools/mach-types).
 
-4. Setup boot data
-------------------
+
+4. Setup the kernel tagged list
+-------------------------------
 
 Existing boot loaders:		OPTIONAL, HIGHLY RECOMMENDED
 New boot loaders:		MANDATORY
 
-The boot loader must provide either a tagged list or a dtb image for
-passing configuration data to the kernel.  The physical address of the
-boot data is passed to the kernel in register r2.
-
-4a. Setup the kernel tagged list
---------------------------------
-
 The boot loader must create and initialise the kernel tagged list.
 A valid tagged list starts with ATAG_CORE and ends with ATAG_NONE.
 The ATAG_CORE tag may or may not be empty.  An empty ATAG_CORE tag
@@ -107,24 +101,6 @@ The tagged list must be placed in a region of memory where neither
 the kernel decompressor nor initrd 'bootp' program will overwrite
 it.  The recommended placement is in the first 16KiB of RAM.
 
-4b. Setup the device tree
--------------------------
-
-The boot loader must load a device tree image (dtb) into system ram
-at a 64bit aligned address and initialize it with the boot data.  The
-dtb format is documented in Documentation/devicetree/booting-without-of.txt.
-The kernel will look for the dtb magic value of 0xd00dfeed at the dtb
-physical address to determine if a dtb has been passed instead of a
-tagged list.
-
-The boot loader must pass at a minimum the size and location of the
-system memory, and the root filesystem location.  The dtb must be
-placed in a region of memory where the kernel decompressor will not
-overwrite it.  The recommended placement is in the first 16KiB of RAM
-with the caveat that it may not be located at physical address 0 since
-the kernel interprets a value of 0 in r2 to mean neither a tagged list
-nor a dtb were passed.
-
 5. Calling the kernel image
 ---------------------------
 
@@ -149,8 +125,7 @@ In either case, the following conditions must be met:
 - CPU register settings
   r0 = 0,
   r1 = machine type number discovered in (3) above.
-  r2 = physical address of tagged list in system RAM, or
-       physical address of device tree block (dtb) in system RAM
+  r2 = physical address of tagged list in system RAM.
 
 - CPU mode
   All forms of interrupts must be disabled (IRQs and FIQs)

Documentation/devicetree/booting-without-of.txt

@@ -13,7 +13,6 @@ Table of Contents
 
   I - Introduction
     1) Entry point for arch/powerpc
-    2) Entry point for arch/arm
 
   II - The DT block format
     1) Header
@@ -226,45 +225,6 @@ it with special cases.
   cannot support both configurations with Book E and configurations
   with classic Powerpc architectures.
 
-2) Entry point for arch/arm
----------------------------
-
-   There is one single entry point to the kernel, at the start
-   of the kernel image. That entry point supports two calling
-   conventions.  A summary of the interface is described here.  A full
-   description of the boot requirements is documented in
-   Documentation/arm/Booting
-
-        a) ATAGS interface.  Minimal information is passed from firmware
-        to the kernel with a tagged list of predefined parameters.
-
-                r0 : 0
-
-                r1 : Machine type number
-
-                r2 : Physical address of tagged list in system RAM
-
-        b) Entry with a flattened device-tree block.  Firmware loads the
-        physical address of the flattened device tree block (dtb) into r2,
-        r1 is not used, but it is considered good practise to use a valid
-        machine number as described in Documentation/arm/Booting.
-
-                r0 : 0
-
-                r1 : Valid machine type number.  When using a device tree,
-                a single machine type number will often be assigned to
-                represent a class or family of SoCs.
-
-                r2 : physical pointer to the device-tree block
-                (defined in chapter II) in RAM.  Device tree can be located
-                anywhere in system RAM, but it should be aligned on a 32 bit
-                boundary.
-
-   The kernel will differentiate between ATAGS and device tree booting by
-   reading the memory pointed to by r1 and looking for either the flattened
-   device tree block magic value (0xd00dfeed) or the ATAG_CORE value at
-   offset 0x4 from r2 (0x54410001).
-
 
 II - The DT block format
 ========================