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authorBjorn Andersson <bjorn.andersson@sonymobile.com>2014-09-29 07:45:31 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2015-01-05 09:43:38 +0000
commit70691b13d2b7876ab50f68ccba1c604d9b181fb2 (patch)
treece61d76151d3d00b7c31f8ec60c5d74dfb353f81
parent1b213f2e3b4bf0be4b3db2f77ba2ca3649142d18 (diff)
downloadlinux-70691b13d2b7876ab50f68ccba1c604d9b181fb2.tar.gz
fixup: ATAG MEM fixup loader for Qualcomm devices
The fixup.bin will when prepended to zImage fixup the atag mem such that the kernel will be happy. Without this a panic will occur upon freeing bootmem. Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
-rw-r--r--fixup.S84
-rw-r--r--fixup.binbin0 -> 84 bytes
-rw-r--r--fixup.txt17
3 files changed, 101 insertions, 0 deletions
diff --git a/fixup.S b/fixup.S
new file mode 100644
index 000000000000..42d27fc0c949
--- /dev/null
+++ b/fixup.S
@@ -0,0 +1,84 @@
+/* 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:
diff --git a/fixup.bin b/fixup.bin
new file mode 100644
index 000000000000..67f2a17eaaa8
--- /dev/null
+++ b/fixup.bin
Binary files differ
diff --git a/fixup.txt b/fixup.txt
new file mode 100644
index 000000000000..07bcb3c52a0d
--- /dev/null
+++ b/fixup.txt
@@ -0,0 +1,17 @@
+
+Fixup loader to boot mainline on Qualcomm platforms that needs adjustment of
+ATAG MEM.
+
+Found at [1], built by issuing:
+
+ arm-eabi-as -o fixup.o fixup.S
+ arm-eabi-objcopy -O binary fixup.o fixup.bin
+
+
+Use by concatenating together with zImage:
+
+ cat fixup.bin arch/arm/boot/zImage > zImage
+
+
+[1] https://www.codeaurora.org/cgit/quic/kernel/skales/tree/atag-fix/fixup.S
+