diff options
Diffstat (limited to 'rbutil/mkamsboot/dualboot.S')
| -rw-r--r-- | rbutil/mkamsboot/dualboot.S | 126 |
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 */ |