summaryrefslogtreecommitdiffstats
path: root/rbutil/mkamsboot/dualboot.S
diff options
context:
space:
mode:
authorDave Chapman <dave@dchapman.com>2008-10-11 11:35:59 +0000
committerDave Chapman <dave@dchapman.com>2008-10-11 11:35:59 +0000
commit1c4bcfac691d4473cf513ba958c8edbdc8c97939 (patch)
treed9a4a2c8138608c5ae7728fcf24e247024a8416f /rbutil/mkamsboot/dualboot.S
parentced0adc527b44c3041a2ac0a4a3a5c9cd805531e (diff)
downloadrockbox-1c4bcfac691d4473cf513ba958c8edbdc8c97939.tar.gz
rockbox-1c4bcfac691d4473cf513ba958c8edbdc8c97939.zip
Major rework of mkamsboot, extending work done by Rafael Carre. We now build one "dualboot.bin" mini-bootloader per target and embed it in the mkamsboot binary. The user of mkamsboot just needs to provide an original firmware file, and a Rockbox bootloader file. This code currently supports just the Clip (hardware revision 1) and the E200v2 - button checks are needed for the other V2 targets. NOTE: This is completely untested on-target, and may brick your device.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18767 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'rbutil/mkamsboot/dualboot.S')
-rw-r--r--rbutil/mkamsboot/dualboot.S126
1 files changed, 126 insertions, 0 deletions
diff --git a/rbutil/mkamsboot/dualboot.S b/rbutil/mkamsboot/dualboot.S
new file mode 100644
index 0000000000..786f610aef
--- /dev/null
+++ b/rbutil/mkamsboot/dualboot.S
@@ -0,0 +1,126 @@
+.text
+
+/* This is the size of the Clip's RAM, but there is nothing to be gained
+ (at the moment) by making use of the larger RAM of other targets */
+
+.set DRAM_SIZE, 0x50000
+
+.set GPIOA, 0xC80B0000
+.set GPIOB, 0xC80C0000
+.set GPIOC, 0xC80D0000
+.set GPIOD, 0xC80E0000
+.set CGU_PERI, 0xC80F0014
+
+
+/* Vectors */
+ ldr pc, =start
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+.word 0
+
+/* These values are filled in by mkamsboot - don't move them from offset 0x20 */
+uclunpack_end: .word 0 /* End of the ucl_unpack function */
+uclunpack_size: .word 0 /* Size in bytes of the ucl_unpack function */
+
+ucl_of_end: .word 0 /* End of the ucl-compressed OF image */
+ucl_of_size: .word 0 /* Size in bytes of the compressed OF image */
+
+ucl_rb_end: .word 0 /* End of the ucl-compressed RB image */
+ucl_rb_size: .word 0 /* Size in bytes of the compressed RB image */
+
+
+start:
+ /* First copy the UCL unpack function to the end of RAM */
+ ldr r0, uclunpack_end /* Source */
+ ldr r1, uclunpack_size /* Source length */
+ sub r2, r0, r1 /* Source start - 1*/
+
+ ldr r3, =DRAM_SIZE /* Destination end */
+
+uclcopy:
+ ldrb r4, [r0], #-1
+ strb r4, [r3], #-1
+ cmp r2, r3
+ bne uclcopy
+
+ add r5, r2, #2 /* r5 is entry point of copy of uclunpack */
+ /* function, plus one (for thumb mode */
+
+ /* enable gpio clock */
+ ldr r0, =CGU_PERI
+ ldr r1, [r0]
+ orr r1, r1, #(1<<16)
+ str r1, [r0]
+
+ /* we check A3 unconditionally of the model because it seems to be */
+ /* either hold, either usb on every model */
+
+ ldr r0, =GPIOA
+ mov r1, #0
+ str r1, [r0, #0x400]
+ ldr r1, [r0, #0x20] /* read pin A3 */
+
+ cmp r1, #0
+ bne boot_of
+
+ /* here are model specific tests, for dual boot without a computer */
+
+#ifdef SANSA_CLIP
+ /* HOME button */
+ ldr r0, =GPIOB
+ mov r1, #0
+ str r1, [r0, #0x400]
+ ldr r1, [r0, #0x10] /* read pin B2 */
+
+ cmp r1, #0
+ bne boot_of
+#elif defined(SANSA_E200V2)
+ /* DOWN button */
+ ldr r0, =GPIOC
+ mov r1, #0
+ str r1, [r0, #0x400]
+ ldr r1, [r0, #0x100] /* read pin C6 */
+
+ cmp r1, #0 /* C6 = #0 means button pressed */
+ beq boot_of
+#else
+ #error No target-specific key check defined!
+#endif
+
+ /* No button was held, so we boot rockbox */
+ ldr r0, ucl_rb_end /* Address of compressed image */
+ ldr r1, ucl_rb_size /* Compressed size */
+ b decompress
+
+boot_of:
+ ldr r0, ucl_of_end /* Address of compressed image */
+ ldr r1, ucl_of_size /* Compressed size */
+
+
+decompress:
+ /* At this point: */
+ /* r5 = entry point (plus one for thumb) of uclunpack function */
+ /* r3 = destination_end for copy of UCL image */
+ /* r0 = source_end for UCL image to copy */
+ /* r1 = size of UCL image to copy */
+
+ sub r4, r3, r1 /* r4 := destination_start - 1 */
+
+fw_copy:
+ ldrb r2, [r0], #-1
+ strb r2, [r3], #-1
+ cmp r3, r4 /* Stop when we reached dest_start-1 */
+ bne fw_copy
+
+ /* Call the ucl decompress function, which will branch to 0x0 */
+ /* on completion */
+ add r0, r3, #1 /* r0 := Start of compressed image */
+ /* r1 already contains compressed size */
+ mov r2, #0 /* r2 := Destination for unpacking */
+ bx r5 /* Branch to uclunpack, switching to thumb */
+
+ /* never reached */