Arnaud VALLEY / Mbed 2 deprecated Pinscape_Controller_V2_arnoz

Mirror with some correction

Dependencies:   mbed FastIO FastPWM USBDevice

FreescaleIAP/IAP.s@116:7a67265d7c19, 2021-10-01 (annotated)

Committer:
arnoz
Date:
Fri Oct 01 08:19:46 2021 +0000
Revision:
116:7a67265d7c19
Parent:
101:755f44622abc 
- Correct information regarding your last merge

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 76:7f5912b6340e 1 ; FreescaleIAP assembly functions
mjr 76:7f5912b6340e 2 ;
mjr 79:682ae3171a08 3 ; The hardware manual warns that FTFA commands must be executed entirely
mjr 79:682ae3171a08 4 ; from RAM code, since we can't have any flash reads occur while an erase
mjr 79:682ae3171a08 5 ; or write operation is executing. If the code executing and waiting for
mjr 79:682ae3171a08 6 ; the FTFA command were in flash, the CPU might have to fetch an instruction
mjr 79:682ae3171a08 7 ; from flash in the course of the loop, which could freeze the CPU.
mjr 79:682ae3171a08 8 ; Empirically, it seems that this isn't truly necessary, despite the manual's
mjr 79:682ae3171a08 9 ; warnings. The M0+ instruction cache is big enough to hold the whole
mjr 101:755f44622abc 10 ; execute-and-wait loop instruction sequence, even when written in C++, so
mjr 79:682ae3171a08 11 ; in practice this can run as flash-resident C++ code. We're implementing
mjr 79:682ae3171a08 12 ; it as assembler anyway to follow the best practices as laid out in the
mjr 79:682ae3171a08 13 ; hardware manual.
mjr 79:682ae3171a08 14 ;
mjr 79:682ae3171a08 15 ; Tell the linker to put our code in RAM by making it read-write.
mjr 79:682ae3171a08 16 AREA iap_ram_asm_code, CODE, READWRITE
mjr 76:7f5912b6340e 17
mjr 76:7f5912b6340e 18
mjr 79:682ae3171a08 19 ; iapExecAndWait()
mjr 77:0b96f6867312 20 ;
mjr 79:682ae3171a08 21 ; Launches the currently loaded FTFA command and waits for completion.
mjr 79:682ae3171a08 22 ; Before calling, the caller must set up the FTFA command registers with
mjr 79:682ae3171a08 23 ; the command code and any address and data parameters required. The
mjr 79:682ae3171a08 24 ; caller should also disable interrupts, since an interrupt handler could
mjr 79:682ae3171a08 25 ; cause a branch into code resident in flash memory, which would violate
mjr 79:682ae3171a08 26 ; the rule against accessing flash while an FTFA command is running.
mjr 77:0b96f6867312 27
mjr 77:0b96f6867312 28 EXPORT iapExecAndWait
mjr 77:0b96f6867312 29 iapExecAndWait
mjr 76:7f5912b6340e 30 ; save registers
mjr 79:682ae3171a08 31 STMFD R13!, {R1,R2,LR}
mjr 77:0b96f6867312 32
mjr 79:682ae3171a08 33 ; disable interrupts
mjr 79:682ae3171a08 34 CPSID I ; set the PRIMASK to disable interrupts
mjr 78:1e00b3fa11af 35 DSB ; data synchronization barrier
mjr 77:0b96f6867312 36 ISB ; instruction synchronization barrier
mjr 79:682ae3171a08 37
mjr 77:0b96f6867312 38 ; Launch the command by writing the CCIF bit to FTFA_FSTAT
mjr 79:682ae3171a08 39 LDR R0, FTFA_FSTAT
mjr 79:682ae3171a08 40 MOVS R2, #0x80 ; CCIF (0x80)
mjr 79:682ae3171a08 41 STRB R2, [R0] ; FTFA->FSTAT = CCIF
mjr 76:7f5912b6340e 42
mjr 77:0b96f6867312 43 ; Wait for the command to complete. The FTFA sets the CCIF
mjr 77:0b96f6867312 44 ; bit in FTFA_FSTAT when the command is finished, so spin until
mjr 77:0b96f6867312 45 ; the bit reads as set.
mjr 77:0b96f6867312 46 Lew0
mjr 77:0b96f6867312 47 LDRB R1, [R0] ; R1 <- FTFA->FSTAT
mjr 77:0b96f6867312 48 TSTS R1, R2 ; test R1 & CCIF
mjr 77:0b96f6867312 49 BEQ Lew0 ; if zero, the command is still running
mjr 77:0b96f6867312 50
mjr 79:682ae3171a08 51 ; re-enable interrupts
mjr 79:682ae3171a08 52 CPSIE I
mjr 77:0b96f6867312 53
mjr 76:7f5912b6340e 54 ; pop registers and return
mjr 79:682ae3171a08 55 LDMFD R13!, {R1,R2,PC}
mjr 77:0b96f6867312 56
mjr 78:1e00b3fa11af 57 ALIGN
mjr 79:682ae3171a08 58 FTFA_FSTAT DCD 0x40020000
mjr 78:1e00b3fa11af 59
mjr 59:94eb9265b6d7 60 END