summaryrefslogtreecommitdiffstats
path: root/Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S
diff options
context:
space:
mode:
authorSven Eisenhauer <sven@sven-eisenhauer.net>2023-11-10 15:11:48 +0100
committerSven Eisenhauer <sven@sven-eisenhauer.net>2023-11-10 15:11:48 +0100
commit33613a85afc4b1481367fbe92a17ee59c240250b (patch)
tree670b842326116b376b505ec2263878912fca97e2 /Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S
downloadStudium-33613a85afc4b1481367fbe92a17ee59c240250b.tar.gz
Studium-33613a85afc4b1481367fbe92a17ee59c240250b.tar.bz2
add new repoHEADmaster
Diffstat (limited to 'Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S')
-rw-r--r--Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S405
1 files changed, 405 insertions, 0 deletions
diff --git a/Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S b/Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S
new file mode 100644
index 0000000..c7c8d83
--- /dev/null
+++ b/Bachelor/Mikroprozessorsysteme2/mi2/Termin5/boot.S
@@ -0,0 +1,405 @@
+@-----------------------------------------------------------------------------
+@- File source : boot.S
+@- Object : Bootfile fuer Praktikum
+@-
+@- 1.0 17/09/02 GR : Creation
+@- letzte Änderung : 11/11/02
+@------------------------------------------------------------------------------
+
+#include "aic.inc"
+#include "ebi.inc"
+
+@------------------------------------------------------------------------------
+@- Area Definition
+@-----------------
+@- Must be defined as function to put first in the code as it must be mapped
+@- at SRAM.
+@------------------------------------------------------------------------------
+
+ .text
+
+
+ .global _start
+@------------------------------------------------------------------------------
+@- Define the entry point
+@------------------------
+_start:
+
+@------------------------------------------------------------------------------
+@- Exception vectors
+@------------------------------------------------------------------------------
+
+Reset: B InitReset @ reset
+undefvec: B undefvec @ Undefined Instruction
+swivec: B swivec @ Software Interrupt
+pabtvec: B pabtvec @ Prefetch Abort
+dabtvec: B dabtvec @ Data Abort
+rsvdvec: B rsvdvec @ reserved
+irqvec: B irqvec @ reserved
+fiqvec: B fiqvec @ reserved
+
+@------------------------------------------------------------------------------
+@- Exception vectors ( after cstartup execution )
+@------------------------------------
+@- These vectors are read at RAM address after the remap command is performed in
+@- the EBI. As they will be relocated at address 0x0 to be effective, a
+@- relative addressing is forbidden. The only possibility to get an absolute
+@- addressing for an ARM vector is to read a PC relative value at a defined
+@- offset. It is easy to reserve the locations 0x20 to 0x3C (the 8 next
+@- vectors) for storing the absolute exception handler address.
+@- The AIC vectoring access vectors are saved in the interrupt and fast
+@- interrupt ARM vectors. So, only 5 offsets are required ( reserved vector
+@- offset is never used).
+@- The provisory handler addresses are defined on infinite loop and can be
+@- modified at any time.
+@- Note also that the reset is only accessible by a jump from the application
+@- to 0. It is an actual software reset.
+@- As the 13 first location are used by the vectors, the read/write link
+@- address must be defined from 0x34 if internal data mapping is required.
+@- (use for that the option -rw- base=0x34
+@------------------------------------------------------------------------------
+
+VectorTable:
+ ldr pc, [pc, #0x18] @ SoftReset
+ ldr pc, [pc, #0x18] @ UndefHandler
+ ldr pc, [pc, #0x18] @ SWIHandler
+ ldr pc, [pc, #0x18] @ PrefetchAbortHandler
+ ldr pc, [pc, #0x18] @ DataAbortHandler
+ nop @ Reserved
+ ldr pc, [pc,#-0xF20] @ IRQ : read the AIC
+ ldr pc, [pc,#-0xF20] @ FIQ : read the AIC
+
+@- There are only 5 offsets as the vectoring is used.
+ .word _SoftReset
+ .word _UndefHandler
+ .word SWIHandler
+ .word _PrefetchAbortHandler
+ .word _DataAbortHandler
+
+@- Vectoring Execution function run at absolut addresss
+_SoftReset: b _SoftReset
+_UndefHandler: b _UndefHandler
+_SWIHandler: b _SWIHandler
+_PrefetchAbortHandler: b _PrefetchAbortHandler
+_DataAbortHandler: b _DataAbortHandler
+
+
+
+InitTableEBI:
+ .word EBI_CSR_0
+ .word EBI_CSR_1
+ .word EBI_CSR_2
+ .word EBI_CSR_3
+ .word EBI_CSR_4
+ .word EBI_CSR_5
+ .word EBI_CSR_6
+ .word EBI_CSR_7
+ .word 0x00000001 @ REMAP command
+ .word 0x00000006 @ 6 memory regions, standard read
+PtEBIBase:
+ .word EBI_BASE @ EBI Base Address
+
+@------------------------------------------------------------------------------
+@- The reset handler before Remap
+@--------------------------------
+@- From here, the code is executed from SRAM address
+@------------------------------------------------------------------------------
+InitReset:
+
+@------------------------------------------------------------------------------
+@- Speed up the Boot sequence
+@----------------------------
+@- After reset, the number os wait states on chip select 0 is 8. All AT91
+@- Evaluation Boards fits fast flash memories, so that the number of wait
+@- states can be optimized to fast up the boot sequence.
+@- ICE note :For ICE debug no need to set the EBI value these values already set
+@- by the boot function.
+@------------------------------------------------------------------------------
+@- Load System EBI Base address and CSR0 Init Value
+ ldr r0, PtEBIBase
+ ldr r1, InitTableEBI @ values (relative)
+
+@- Speed up code execution by disabling wait state on Chip Select 0
+ str r1, [r0]
+
+@------------------------------------------------------------------------------
+@- low level init
+@----------------
+@ Call __low_level_init to perform initialization before initializing
+@ AIC and calling main.
+@----------------------------------------------------------------------
+
+@ bl __low_level_init
+
+
+@------------------------------------------------------------------------------
+@- Reset the Interrupt Controller
+@--------------------------------
+@- Normally, the code is executed only if a reset has been actually performed.
+@- So, the AIC initialization resumes at setting up the default vectors.
+@------------------------------------------------------------------------------
+@- Load the AIC Base Address and the default handler addresses
+
+ adr r0, AicData @ @ where to read values (relative)
+
+ ldmia r0, {r1-r4}
+
+@- Setup the Spurious Vector
+ str r4, [r1, #AIC_SPU] @ r4 = spurious handler
+
+
+@ - ICE note : For ICE debug
+@ - Perform 8 End Of Interrupt Command to make sure AIC will not lock out nIRQ
+ mov r0, #8
+LoopAic0:
+ str r1, [r1, #AIC_EOICR] @ any value written
+ subs r0, r0, #1
+ bhi LoopAic0
+
+@- Reset Interrupts
+ mov r0, #0
+ sub r0, r0, #1 @ all bits set
+ str r0, [r1, #AIC_IDCR]
+ str r0, [r1, #AIC_ICCR]
+
+@- Set up the default interrupt handler vectors
+ str r2, [r1, #AIC_SVR] @ SVR[0] for FIQ
+ add r1, r1, #AIC_SVR
+ mov r0, #31 @ counter
+LoopAic1:
+ str r3, [r1, r0, LSL #2] @ SVRs for IRQs
+ subs r0, r0, #1 @ do not save FIQ
+ bhi LoopAic1
+
+ b EndInitAic
+
+@- Default Interrupt Handlers
+AicData:
+ .word AIC_BASE @ AIC Base Address
+@------------------------------------------------------------------------------
+@- Default Interrupt Handler
+@---------------------------
+@- These function are defined in the AT91 library. If you want to change this
+@- you can redifine these function in your appication code
+@------------------------------------------------------------------------------
+
+PtDefaultHandler:
+ .word at91_default_fiq_handler
+ .word at91_default_irq_handler
+ .word at91_spurious_handler
+
+at91_default_fiq_handler: B at91_default_fiq_handler
+at91_default_irq_handler: B at91_default_irq_handler
+at91_spurious_handler: B at91_spurious_handler
+
+EndInitAic:
+
+@------------------------------------------------------------------------------
+@- Setup Exception Vectors in Internal RAM before Remap
+@------------------------------------------------------
+@- That's important to perform this operation before Remap in order to guarantee
+@- that the core has valid vectors at any time during the remap operation.
+@- Note: There are only 5 offsets as the vectoring is used.
+@- ICE note : In this code only the start address value is changed if you use
+@- without Semihosting.
+@- Before Remap the internal RAM it's 0x300000
+@- After Remap the internal RAM it's 0x000000
+@- Remap it's already executed it's no possible to write to 0x300000.
+@------------------------------------------------------------------------------
+@- Copy the ARM exception vectors
+
+ mov r0, #0x28
+ adr r1, Init_Vector
+ str r1,[r0]
+ mov r0, #0x08
+ adr r1, VectorTable+8
+ ldr r1,[r1]
+ str r1,[r0]
+ swi 0
+
+@ The RAM_BASE = 0 it's specific for ICE
+
+ RAM_BASE = 0
+Init_Vector:
+ mov r8, #RAM_BASE @ @ of the hard vector after remap in internal RAM 0x0
+
+ adr r9, VectorTable @ where to read values (relative)
+ ldmia r9!, {r0-r7} @ read 8 vectors
+
+ stmia r8!, {r0-r7} @ store them
+
+ ldmia r9!, {r0-r4} @ read 5 absolute handler addresses
+ stmia r8!, {r0-r4} @ store them
+
+@------------------------------------------------------------------------------
+@- Initialise the Memory Controller
+@----------------------------------
+@- That's principaly the Remap Command. Actually, all the External Bus
+@- Interface is configured with some instructions and the User Interface Image
+@- as described above. The jump "mov pc, r12" could be unread as it is after
+@- located after the Remap but actually it is thanks to the Arm core pipeline.
+@- The IniTableEBI addressing must be relative .
+@- The PtInitRemap must be absolute as the processor jumps at this address
+@- immediatly after the Remap is performed.
+@- Note also that the EBI base address is loaded in r11 by the "ldmia".
+@- ICE note :For ICE debug these values already set by the boot function and the
+@- Remap it's already executed it's no need to set still.
+@------------------------------------------------------------------------------
+@- Copy the Image of the Memory Controller
+ adr r10, InitTableEBI @ get the address of the chip select register image
+ ldr r12, PtInitRemap @ get the real jump address ( after remap )
+
+@- Copy Chip Select Register Image to Memory Controller and command remap
+ ldmia r10!, {r0-r9,r11} @ load the complete image and the EBI base
+ stmia r11!, {r0-r9} @ store the complete image with the remap command
+
+@- Jump to ROM at its new address
+ mov pc, r12 @ jump and break the pipeline
+
+PtInitRemap:
+ .word InitRemap @ address where to jump after REMAP
+
+@------------------------------------------------------------------------------
+@- The Reset Handler after Remap
+@-------------------------------
+@- From here, the code is continous execute from its link address.
+@------------------------------------------------------------------------------
+
+InitRemap:
+
+@--------------------------------
+@- ARM Core Mode and Status Bits
+@--------------------------------
+
+ARM_MODE_USER = 0x10
+ARM_MODE_FIQ = 0x11
+ARM_MODE_IRQ = 0x12
+ARM_MODE_SVC = 0x13
+ARM_MODE_ABORT = 0x17
+ARM_MODE_UNDEF = 0x1B
+ARM_MODE_SYS = 0x1F
+
+I_BIT = 0x80
+F_BIT = 0x40
+T_BIT = 0x20
+
+@------------------------------------------------------------------------------
+@- Stack Sizes Definition
+@------------------------
+@- Interrupt Stack requires 3 words x 8 priority level x 4 bytes when using
+@- the vectoring. This assume that the IRQ_ENTRY/IRQ_EXIT macro are used.
+@- The Interrupt Stack must be adjusted depending on the interrupt handlers.
+@- Fast Interrupt is the same than Interrupt without priority level.
+@- Other stacks are defined by default to save one word each.
+@- The System stack size is not defined and is limited by the free internal
+@- SRAM.
+@- User stack size is not defined and is limited by the free external SRAM.
+@------------------------------------------------------------------------------
+
+IRQ_STACK_SIZE = (3*8*4) @ 3 words per interrupt priority level
+FIQ_STACK_SIZE = (3*4) @ 3 words
+ABT_STACK_SIZE = (1*4) @ 1 word
+UND_STACK_SIZE = (1*4) @ 1 word
+
+@------------------------------------------------------------------------------
+@- Top of Stack Definition
+@-------------------------
+@- Fast Interrupt, Interrupt, Abort, Undefined and Supervisor Stack are located
+@- at the top of internal memory in order to speed the exception handling
+@- context saving and restoring.
+@- User (Application, C) Stack is located at the top of the external memory.
+@------------------------------------------------------------------------------
+RAM_BASE = 0
+RAM_SIZE = (2*1024)
+RAM_LIMIT = (RAM_BASE+RAM_SIZE)
+EXT_SRAM_BASE = 0x02000000
+EXT_SRAM_SIZE = 0x00040000 @ 256Kbytes
+EXT_SRAM_LIMIT = (EXT_SRAM_BASE+EXT_SRAM_SIZE)
+
+TOP_EXCEPTION_STACK = RAM_LIMIT @ Defined in part
+TOP_APPLICATION_STACK = EXT_SRAM_LIMIT @ Defined in Target
+
+@------------------------------------------------------------------------------
+@- Setup the stack for each mode
+@-------------------------------
+ ldr r0, =TOP_EXCEPTION_STACK
+
+@- Set up Fast Interrupt Mode and set FIQ Mode Stack
+ msr CPSR_c, #ARM_MODE_FIQ | I_BIT |F_BIT
+ mov r13, r0 @ Init stack FIQ
+ sub r0, r0, #FIQ_STACK_SIZE
+
+@- Set up Interrupt Mode and set IRQ Mode Stack
+ msr CPSR_c, #ARM_MODE_IRQ | I_BIT |F_BIT
+ mov r13, r0 @ Init stack IRQ
+ sub r0, r0, #IRQ_STACK_SIZE
+
+@- Set up Abort Mode and set Abort Mode Stack
+ msr CPSR_c, #ARM_MODE_ABORT | I_BIT | F_BIT
+ mov r13, r0 @ Init stack Abort
+ sub r0, r0, #ABT_STACK_SIZE
+
+@- Set up Undefined Instruction Mode and set Undef Mode Stack
+ msr CPSR_c, #ARM_MODE_UNDEF | I_BIT | F_BIT
+ mov r13, r0 @ Init stack Undef
+ sub r0, r0, #UND_STACK_SIZE
+
+@- Set up Supervisor Mode and set Supervisor Mode Stack
+ msr CPSR_c, #ARM_MODE_SVC | I_BIT | F_BIT
+ mov sp, r0 @ Init stack Sup
+@------------------------------------------------------------------------------
+@- Setup Application Operating Mode and Enable the interrupts
+@------------------------------------------------------------
+@- System Mode is selected first and the stack is setup. This allows to prevent
+@- any interrupt occurence while the User is not initialized. System Mode is
+@- used as the interrupt enabling would be avoided from User Mode (CPSR cannot
+@- be written while the core is in User Mode).
+@------------------------------------------------------------------------------
+ msr CPSR_c, #ARM_MODE_USER @ set User mode
+ ldr sp, =TOP_APPLICATION_STACK @ Init stack User
+
+@------------------------------------------------------------------------------
+@- Initialise C variables
+@------------------------
+@- Following labels are automatically generated by the linker.
+@- RO: Read-only = the code
+@- RW: Read Write = the data pre-initialized and zero-initialized.
+@- ZI: Zero-Initialized.
+@- Pre-initialization values are located after the code area in the image.
+@- Zero-initialized datas are mapped after the pre-initialized.
+@- Note on the Data position :
+@- If using the ARMSDT, when no -rw-base option is used for the linker, the
+@- data area is mapped after the code. You can map the data either in internal
+@- SRAM ( -rw-base=0x40 or 0x34) or in external SRAM ( -rw-base=0x2000000 ).
+@- Note also that to improve the code density, the pre_initialized data must
+@- be limited to a minimum.
+@------------------------------------------------------------------------------
+
+ ldr r3, = __bss_start__ @ Zero init base => top of init
+NoRW: ldr r1, = __bss_end__ @ Top of zero init segment
+ mov r2, #0
+LoopZI: cmp r3, r1 @ Zero init
+ strcc r2, [r3], #4
+ bcc LoopZI
+
+
+
+@------------------------------------------------------------------------------
+@- Branch on C code Main function (with interworking)
+@----------------------------------------------------
+@- Branch must be performed by an interworking call as either an ARM or Thumb
+@- main C function must be supported. This makes the code not position-
+@- independant. A Branch with link would generate errors
+@------------------------------------------------------------------------------
+
+ bl main
+
+@------------------------------------------------------------------------------
+@- Loop for ever
+@---------------
+@- End of application. Normally, never occur.
+@- Could jump on Software Reset ( B 0x0 ).
+@------------------------------------------------------------------------------
+End:
+ b End
+ .END