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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-27 19:51:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-27 19:51:32 -0700
commit2a56d2220284b0e4dd8569fa475d7053f1c40a63 (patch)
tree96f959486a2f31db599e5f97167074bd1ecb3dc6 /Documentation
parent46f2cc80514e389bacfb642a32a4181fa1f1d20b (diff)
parent239df0fd5ee25588f8a5ba7f7ee646940cc403f4 (diff)
Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (45 commits) ARM: 6945/1: Add unwinding support for division functions ARM: kill pmd_off() ARM: 6944/1: mm: allow ASID 0 to be allocated to tasks ARM: 6943/1: mm: use TTBR1 instead of reserved context ID ARM: 6942/1: mm: make TTBR1 always point to swapper_pg_dir on ARMv6/7 ARM: 6941/1: cache: ensure MVA is cacheline aligned in flush_kern_dcache_area ARM: add sendmmsg syscall ARM: 6863/1: allow hotplug on msm ARM: 6832/1: mmci: support for ST-Ericsson db8500v2 ARM: 6830/1: mach-ux500: force PrimeCell revisions ARM: 6829/1: amba: make hardcoded periphid override hardware ARM: 6828/1: mach-ux500: delete SSP PrimeCell ID ARM: 6827/1: mach-netx: delete hardcoded periphid ARM: 6940/1: fiq: Briefly document driver responsibilities for suspend/resume ARM: 6938/1: fiq: Refactor {get,set}_fiq_regs() for Thumb-2 ARM: 6914/1: sparsemem: fix highmem detection when using SPARSEMEM ARM: 6913/1: sparsemem: allow pfn_valid to be overridden when using SPARSEMEM at91: drop at572d940hf support at91rm9200: introduce at91rm9200_set_type to specficy cpu package at91: drop boot_params and PLAT_PHYS_OFFSET ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/arm/Booting33
-rw-r--r--Documentation/arm/Samsung/Overview.txt2
-rw-r--r--Documentation/devicetree/booting-without-of.txt48
3 files changed, 73 insertions, 10 deletions
diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting
index 76850295af8..4e686a2ed91 100644
--- a/Documentation/arm/Booting
+++ b/Documentation/arm/Booting
@@ -65,13 +65,19 @@ 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 the kernel tagged list
--------------------------------
+4. Setup boot data
+------------------
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
@@ -101,6 +107,24 @@ 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
---------------------------
@@ -125,7 +149,8 @@ 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.
+ r2 = physical address of tagged list in system RAM, or
+ physical address of device tree block (dtb) in system RAM
- CPU mode
All forms of interrupts must be disabled (IRQs and FIQs)
diff --git a/Documentation/arm/Samsung/Overview.txt b/Documentation/arm/Samsung/Overview.txt
index c3094ea51aa..658abb258ce 100644
--- a/Documentation/arm/Samsung/Overview.txt
+++ b/Documentation/arm/Samsung/Overview.txt
@@ -14,7 +14,6 @@ Introduction
- S3C24XX: See Documentation/arm/Samsung-S3C24XX/Overview.txt for full list
- S3C64XX: S3C6400 and S3C6410
- S5P6440
- - S5P6442
- S5PC100
- S5PC110 / S5PV210
@@ -36,7 +35,6 @@ Configuration
unifying all the SoCs into one kernel.
s5p6440_defconfig - S5P6440 specific default configuration
- s5p6442_defconfig - S5P6442 specific default configuration
s5pc100_defconfig - S5PC100 specific default configuration
s5pc110_defconfig - S5PC110 specific default configuration
s5pv210_defconfig - S5PV210 specific default configuration
diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt
index 50619a0720a..7c1329de059 100644
--- a/Documentation/devicetree/booting-without-of.txt
+++ b/Documentation/devicetree/booting-without-of.txt
@@ -12,8 +12,9 @@ Table of Contents
=================
I - Introduction
- 1) Entry point for arch/powerpc
- 2) Entry point for arch/x86
+ 1) Entry point for arch/arm
+ 2) Entry point for arch/powerpc
+ 3) Entry point for arch/x86
II - The DT block format
1) Header
@@ -148,7 +149,46 @@ upgrades without significantly impacting the kernel code or cluttering
it with special cases.
-1) Entry point for arch/powerpc
+1) 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 64 bit
+ boundary.
+
+ The kernel will differentiate between ATAGS and device tree booting by
+ reading the memory pointed to by r2 and looking for either the flattened
+ device tree block magic value (0xd00dfeed) or the ATAG_CORE value at
+ offset 0x4 from r2 (0x54410001).
+
+2) Entry point for arch/powerpc
-------------------------------
There is one single entry point to the kernel, at the start
@@ -226,7 +266,7 @@ it with special cases.
cannot support both configurations with Book E and configurations
with classic Powerpc architectures.
-2) Entry point for arch/x86
+3) Entry point for arch/x86
-------------------------------
There is one single 32bit entry point to the kernel at code32_start,