inittcm.s

arm7的源代码

;;  Copyright ARM Ltd 2002. All rights reserved.
;;
;;  This code initialises the TCMs before calling MMU Initialisation
;;  this allows scatter loading to relocate code into the TCMs
;;
;;  This code must be run from a privileged mode

; TCM region size definitions

Region_0K      EQU 0
Region_4K      EQU 2_0011
Region_8K      EQU 2_0100
Region_16K     EQU 2_0101
Region_32K     EQU 2_0110
Region_64K     EQU 2_0111
Region_128K    EQU 2_1000
Region_256K    EQU 2_1001
Region_512K    EQU 2_1010
Region_1M      EQU 2_1011

Region_Enable  EQU 2_1


; --- Standard definitions of mode bits and interrupt (I & F) flags in PSRs

Mode_USR        EQU     0x10
Mode_FIQ        EQU     0x11
Mode_IRQ        EQU     0x12
Mode_SVC        EQU     0x13
Mode_ABT        EQU     0x17
Mode_UND        EQU     0x1B
Mode_SYS        EQU     0x1F ; available on ARM Arch 4 and later

I_Bit           EQU     0x80 ; when I bit is set, IRQ is disabled
F_Bit           EQU     0x40 ; when F bit is set, FIQ is disabled


        AREA   INIT926TCM, CODE, READONLY   ; name this block of code

        ENTRY

entrypoint

        IMPORT Data_TCM_Base


; if MMU/MPU enabled - disable (useful for ARMulator tests)
;
;
        MRC     p15, 0, r0, c1, c0, 0       ; read CP15 register 1 into r0
        BIC     r0, r0, #0x1                ; clear bit 0
        MCR     p15, 0, r0, c1, c0, 0       ; write value back

;
; Next block sets the TCMs base and size registers to their actual size
; Note TCM actual size is stored in the registers at reset.
;
;
;;TCM Configuration
;==================
;
; Set I and D TCM base and size
;
        LDR     r0,=Data_TCM_Base           ; Read D-TCM Base - set by scatter file
        MRC     p15, 0, r1, c9, c1, 0       ; Read D-TCM
        ORR     r1, r1, r0                  ; Set D-TCM Base address  

 IF :DEF: TCM 	                            ; If BuildTCM option, enable TCMs
        ORR     r1, r1, #Region_Enable
 ELSE
        BIC     r1, r1, #Region_Enable      ; otherwise disable TCMs
 ENDIF
        MCR     p15, 0, r1, c9, c1, 0       ; Set Data TCM

        MOV     r0, #0                      ; I-TCM placed at 0x0 in this example
        MRC     p15, 0, r1, c9, c1, 1       ; Read I-TCM
        ORR     r1, r1, r0                  ; Set I-TCM Base address

 IF :DEF: TCM
        ORR     r1, r1, #Region_Enable
 ELSE
        BIC     r1, r1, #Region_Enable
 ENDIF
        MCR     p15, 0, r1, c9, c1, 1       ; Set I-TCM
;
;
        IMPORT  InitMMUentry                ; Import label to MMU init code

        B       InitMMUentry

        END                                 ; mark the end of this file