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; Copyright 2009 Castle Technology Ltd
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
;     http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
;

        GET     Hdr:ListOpts
        GET     Hdr:Macros
        GET     Hdr:System
        GET     Hdr:Machine.<Machine>
        GET     Hdr:HALSize.<HALSize>

        GET     Hdr:MEMM.VMSAv6

        GET     Hdr:Proc
        GET     Hdr:OSEntries
        GET     Hdr:HALEntries

        GET     hdr.omap3530
        GET     hdr.StaticWS
        GET     hdr.UART
        GET     hdr.Post
        GET     hdr.SDRC
        GET     hdr.Copro15ops
        GET     hdr.GPIO

        AREA    |!!!ROMStart|, CODE, READONLY, PIC

        IMPORT  rom_checkedout_ok
        EXPORT  HAL_Base
        IMPORT  HAL_DebugTX

        MACRO
        CallOSM $entry, $reg
        LDR     ip, [v8, #$entry*4]
        MOV     lr, pc
        ADD     pc, v8, ip
        MEND

        ; Jump table used to select board config on startup
        ; See board.s for ordering of configs, and therefore what entry corresponds to what board
HAL_Base
        BL      selectconfig
        BL      selectconfig
        BL      selectconfig
        BL      selectconfig
        BL      selectconfig
        BL      selectconfig
JumpTableEnd
        ASSERT  . - HAL_Base < 0x60
        %       0x60 - (. - HAL_Base)
ROMsize
        DCD     0 ; patched in by build system. See ROMSizeOffset in Hdr:Machine.Machine
        B       selectconfig_linux ; offset &64 - for booting as a uImage/Linux kernel. Uses Linux machine type ID to select board config.

        ENTRY
selectconfig
        ; Get pointer to board config
        ADR     v1, HAL_Base+4
        SUB     v1, lr, v1
        ADR     a1, BoardConfigTable
        MOV     a2, #BoardConfig_Size>>2
        MLA     v1, a2, v1, a1
foundconfig
        ; v1 = board config
        MSR     CPSR_c, #F32_bit+I32_bit+SVC32_mode ; Get into SVC mode now, so we can write to sb without much fear of losing it (we may have been in FIQ)
 [ Debug
        ; Announce ourselves if debug
        ADR     v2, HelloWorld
        MOV     sb, v1
10      LDRB    a1, [v2], #1
        CMP     a1, #0
        ADRNE   lr, %BT10
        BNE     HAL_DebugTX
        ADD     v2, v1, #BoardConfig_Name
10      LDRB    a1, [v2], #1
        CMP     a1, #0
        ADRNE   lr, %BT10
        BNE     HAL_DebugTX
        MOV     a1, #13
        BL      HAL_DebugTX
        MOV     a1, #10
        BL      HAL_DebugTX
 ]
        ; Now copy the config to SRAM
        ; We'll assume that the L3 interconnect has been correctly configured to give us access
        LDR     sb, =IntSRAM_Base
        MOV     a2, #BoardConfig_Size
10      SUBS    a2, a2, #4
        LDR     a3, [v1, a2]
        STR     a3, [sb, a2]
        BGT     %BT10
        ; Now do common init
        B       restart

 [ Debug
HelloWorld DCB "OMAP3 HAL init",13,10,"Board config=",0
        ALIGN
 ]

        ; Entry point for masquerading as a Linux kernel
        ; r0=0
        ; r1=machine type ID
        ; r2=ptr to tag list (linux/include/asm/setup.h)
selectconfig_linux
        ADR     v1, BoardConfigTable_End-BoardConfig_Size
        ADR     a3, BoardConfigTable
10
        LDR     a1, [v1, #BoardConfig_MachID]
        CMP     a1, a2
        CMPNE   v1, a3 ; If we can't find a config, abort and use default? (i.e. beagleboard)
        BEQ     foundconfig
        SUB     v1, v1, #BoardConfig_Size
        B       %BT10

        LTORG
        GET     board.s
        ASSERT  ((JumpTableEnd-HAL_Base)/4) >= (BoardConfigTable_End-BoardConfigTable)/BoardConfig_Size ; If this fires, we need a bigger jump table!

; ------------------------------------------------------------------------------
; Perform some Cortex-A8 specific CPU setup
; Then start looking for RAM
; In: sb = board config ptr
restart
        DebugChar a3,a4,48
        MSR     CPSR_c, #F32_bit+I32_bit+SVC32_mode
        DebugChar a3,a4,49
        MOV     a1, #&78 ; Matches MMUC_L+MMUC_D+MMUC_P+MMUC_W, which are now reserved bits in the Cortex spec, but should be written as 1
        MCR     p15, 0, a1, c1, c0, 0              ; MMU, caches etc off
        myISB
        DebugChar a3,a4,50
        MRC     p15, 0, a1, c1, c0, 1
        BIC     a1, a1, #2
        MCR     p15, 0, a1, c1, c0, 1 ; Ensure L2 cache disabled
        myISB
        DebugChar a3,a4,51

        MOV     a1, #0
        MCR     p15, 0, a1, c7, c5, 0           ; invalidate instruction cache
        DebugChar a3,a4,52
        MCR     p15, 0, a1, c8, c7, 0           ; invalidate TLBs
        DebugChar a3,a4,53

        ; Invalidate data caches. To do this we must query their sizes
        ; The register describes up to 8 cache levels, so to provide some future-proofing I might as well implement a full cache clean routine here
        MRC     p15, 1, a1, c0, c0, 1 ; Cache level ID register
        DebugChar a3,a4,54
        BIC     a1, a1, #&FF000000 ; Discard unification/coherency bits
        MOV     a2, #0 ; Current cache level
20
        DebugChar a3,a4,49
        ANDS    a3, a1, #7 ; Get flags
        BEQ     %FT10 ; Cache clean complete
        MCR     p15, 2, a2, c0, c0, 0 ; Program cache size selection register
        myISB
        MRC     p15, 1, a3, c0, c0, 0 ; Get size info
        AND     v1, a3, #&7 ; log2(Line size)-2
        BIC     a3, a3, #&F0000007 ; Clear flags & line size
        MOV     v2, a3, LSL #19 ; Number of ways-1 in upper 10 bits
        MOV     v3, a3, LSR #13 ; Number of sets-1 in lower 15 bits
        ; Way number needs to be packed right up at the high end of the data word; shift it up
        CLZ     a4, v2
        MOV     v2, v2, LSL a4
        ; Set number needs to start at log2(Line size)+2
        MOV     v3, v3, LSL #4 ; Start at bit 4
        MOV     v3, v3, LSL v1 ; Start at log2(Line size)+2
        ; Now calculate the offset numbers we will use to increment sets & ways
        BIC     v4, v2, v2, LSL #1 ; Way increment
        BIC     v5, v3, v3, LSL #1 ; Set increment
        ; Now we can finally clean this cache!
        ORR     a3, a2, v3 ; Current way (0), set (max), and level
30
        MCR     p15, 0, a3, c7, c6, 2 ; Invalidate
        ADDS    a3, a3, v4 ; Increment way
        BCC     %BT30 ; Overflow will occur once ways are enumerated
        TST     a3, v3 ; Are set bits all zero?
        SUBNE   a3, a3, v5 ; No, so decrement set and loop around again
        BNE     %BT30
        ; This cache is now clean. Move on to the next level.
        DebugChar a3,a4,50
        ADD     a2, a2, #2
        MOVS    a1, a1, LSR #3
        BNE     %BT20
10
        myDSB
        myISB
        DebugChar a1,a2,51

        ADRL    v1, HAL_Base + OSROM_HALSize    ; v1 -> RISC OS image

        LDR     v8, [v1, #OSHdr_Entries]
        ADD     v8, v8, v1                      ; v8 -> RISC OS entry table

        ARM_read_control a1
        ; We assume that ARMs with an I cache can have it enabled while the MMU is off.
        [ :LNOT:CacheOff
        ORR   a1, a1, #MMUC_I
        ]
        ARM_write_control a1                                ; whoosh
        myISB

        ; Keep a soft copy of the CR in a banked register (R13_und)
        MSR     CPSR_c, #F32_bit+I32_bit+UND32_mode
        MOV     sp, a1
        ; Switch into SVC32 mode (we may have been in SVC26 before).
        MSR     CPSR_c, #F32_bit+I32_bit+SVC32_mode

        ; Initialise RAM
        BL      init_ram

        ; The first 4K of the first registered block of RAM is used by RISC OS's init code, and also contains the stack
        ; To keep things simple and safe, we'll relocate the HAL and OS image to the top end of RAM
        ; Although with the beagleboard we know we'll be booted from RAM, this code has been written so that it should work if running from ROM

        ; First, identify the top end of RAM
        ; Then check if we intersect it
        ; If we do, first copy ourselves down
        ; Then copy ourselves up

relocate_code
        DebugChar a1,a2,66
        BL      get_end_of_ram
        DebugChar v1,v2,67

        ; How big are we?
        ADRL    v1, HAL_Base + OSROM_HALSize
        LDR     v2, [v1, #OSHdr_ImageSize]
        SUB     v1, v1, #OSROM_HALSize ; Start of HAL
        ADD     v2, v2, #OSROM_HALSize ; Size of HAL+OS
        ADD     v3, v1, v2 ; End of OS
        MOV     v4, a1 ; End of RAM
        SUB     v5, v4, v2 ; New start address of HAL
        CMP     v1, v5
        BEQ     %FT10 ; No copy needed
        BHI     %FT20 ; We're in some ROM above RAM. OK to continue with copy.
        CMP     v3, v5
        BLS     %FT20 ; We're in some ROM/RAM below our copy destination. OK to continue with copy.
        ; Else we currently overlap the area we want to copy ourselves into.
        SUB     v5, v1, v2 ; Copy the HAL+OS to just before itself
20
        MOV     a1, v5
        MOV     a2, v1 ; Copy source
        MOV     a3, v2
30
        LDR     a4, [a2], #4
        SUBS    a3, a3, #4
        STR     a4, [a1], #4
        BGT     %BT30
        ; Invalidate I-cache, branch predictors
        MOV     a1, #0
        MCR     p15, 0, a1, c7, c5, 0
        MCR     p15, 0, a1, c7, c5, 6
        myDSB ; Wait for I-cache invalidation to complete
        myISB ; Wait for branch predictor invalidation to complete?
        DebugChar a1,a2,68
        ; Jump to our new copy
        ADR     a1, relocate_code ; Keep things simple by just running through the same code again
        SUB     a2, v5, v1
        ADD     a1, a1, a2 ; relocate our branch target
        ADD     v8, v8, a2 ; Update OS entry table ptr
        MOV     pc, a1
10
        ; Copy completed OK.
        ; v2 = size of HAL+OS
        ; v4 = end of OS/RAM
        ; v5 = start of HAL
        ; v8 = OS entry table ptr
        DebugChar a1,a2,69
        ; Clear RAM up to v5
        MOV     a1, v5
        BL      clear_ram

        DebugChar a1,a2,70

; TODO - NEON seems to be on by default, need to work out how to turn it off before I can test code to turn it on!
;        ; Enable power to the NEON unit, if present
;        LDR     a1, =&4800244C ; 'control OMAP status register'
;        LDR     a1, [a1]
;        TST     a1, #1<<4
;        BNE     %FT10
;;        ; NEON is available, make sure it's turned on
;        ; Enable CP10/CP11 access
;        MRC     p15, 0, a1, c1, c0, 2
;        ORR     a1, a1, #&F<<20
;        MCR     p15, 0, a1, c1, c0, 2
;        DCI     &F57FF06F ; ISB {SY}
;        ; Now enable the unit
;        MOV     a1, #1<<30 ; EN bit
;        DCI     &EEE80A10 ; VMSR FPEXC, a1

        B       rom_checkedout_ok

        GET     RAM.s
        LTORG

        END