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/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* * Neither the name of The Linux Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/* Fixup the atags for dragonboard (and possibly other targets). */
/*
* The bootloader on some targets passes an ATAG in that sets the
* first memory region to be 2MB after the actual start of memory.
* With newer upstream kernels, the PHYS_OFFSET must be a multiple of
* a large boundary (currently 128MB). Without devicetree, we work
* around this with an early init hook, and a fixup that adds a
* reservation. These hooks don't run in time to fix it in Device
* tree.
*
* The following code can be prepended to the zImage. It adjusts the
* memory atag back down to the actual start of memory. The
* assumption is that the device tree will describe the necessary
* memory reservation. The zImage is relocatable, so it is easy to
* prepend this code.
*/
/* Figure out what the broken mem tag would be */
mov r8, pc
and r8, r8, #0xf8000000
add r8, r8, #0x00200000
/* R2 is where the atags are passed. r5 on are scratch. */
mov r5, r2
ldr r7, .tag_mem
.next:
/* Load the tag, and check. */
ldr r6, [r5, #4]
cmp r6, #0
beq .done
/* Is the a 'mem' tag. */
cmp r6, r7
bne .not_mem
/* Is this memory base what we want? */
ldr r6, [r5, #12]
cmp r6, r8
subeq r6, r6, #0x200000
streq r6, [r5, #12]
ldreq r6, [r5, #8]
addeq r6, r6, #0x200000
streq r6, [r5, #8]
.not_mem:
/* Move r5 to the next tag. */
ldr r6, [r5, #0]
add r5, r5, r6, asl #2
b .next
.tag_mem:
.word 0x54410002
.done:
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