[U-Boot-Users] MPC850, read FLASH manufacturer ID, Mxu Board

[Gerhard Butscher]

Hello,

We have an Infineon Switch Evaluation Board (MXU rev.B, MPC850), a
Lauterbach Emulator. We started with the tqm850L configuration (u-boot
0.2.0).

- Reading manufacturer ID of FLASH doesn't work.

Using the VxWorks boot prompt commands it works to write the command
sequence and then read the ID. We now managed to read the ID also with
issuing FLASH writes/reads from Emulator.

The VxWorks boot prompt command uses "sth" assembler command to write
to flash and the u-boot flash_get_size() command uses "stw" assembler
code.

- Could someone explain why "sth" works and "stw" doesn't work in
   our case?

Thanks,
Gerhard



I saw while stepping in assembler, the u-boot code uses following
commands to write the command sequence (first using original long,
then using short which works!):

         short i;
         ulong value;
         ulong base = (ulong)addr;
801F0008            lwz       r0,0x8(r31)    ; r0,8(r31
901F0018            stw       r0,0x18(r31)   ; r0,24(r31
     unsigned short *flash_addr = (unsigned short *)addr
801F0008            lwz       r0,0x8(r31)    ; r0,8(r31
901F001C            stw       r0,0x1C(r31)   ; r0,28(r31
         /* Write auto select command: read Manufacturer ID */
         addr[0x0] = 0xAAAAAAAA
813F0008            lwz       r9,0x8(r31)    ; r9,8(r31
3C00AAAA            lis       r0,-0x5556     ; r0,-21846
6000AAAA            ori       r0,r0,0xAAAA   ; r0,r0,43690
90090000            stw       r0,0x0(r9)     ; r0,0(r9)
         addr[0x0] = 0x55555555;
813F0008            lwz       r9,0x8(r31)    ; r9,8(r31)
3C005555            lis       r0,0x5555      ; r0,2184
60005555            ori       r0,r0,0x5555   ; r0,r0,21845
90090000            stw       r0,0x0(r9)     ; r0,0(r9)
         addr[0x0] = 0x90909090;
813F0008            lwz       r9,0x8(r31)    ; r9,8(r31)
3C009090            lis       r0,-0x6F70     ; r0,-28528
60009090            ori       r0,r0,0x9090   ; r0,r0,37008
90090000            stw       r0,0x0(r9)     ; r0,0(r9

         value = addr[0];
813F0008            lwz       r9,0x8(r31)    ; r9,8(r31)
80090000            lwz       r0,0x0(r9)     ; r0,0(r9
901F0014            stw       r0,0x14(r31)   ; r0,20(r31

         /* Write auto select command: read Manufacturer ID */
         flash_addr[0x0] = 0xAAAA;
813F001C            lwz       r9,0x1C(r31)   ; r9,28(r31
3800AAAA            li        r0,-0x5556     ; r0,-2184
B0090000            sth       r0,0x0(r9)     ; r0,0(r9)
         flash_addr[0x0] = 0x5555;
813F001C            lwz       r9,0x1C(r31)   ; r9,28(r31)
38005555            li        r0,0x5555      ; r0,21845
B0090000            sth       r0,0x0(r9)     ; r0,0(r9)
         flash_addr[0x0] = 0x9090;
813F001C            lwz       r9,0x1C(r31)   ; r9,28(r31)
38009090            li        r0,-0x6F70     ; r0,-28528
B0090000            sth       r0,0x0(r9)     ; r0,0(r9)

         value = addr[0];
813F0008            lwz       r9,0x8(r31)    ; r9,8(r31)
80090000            lwz       r0,0x0(r9)     ; r0,0(r9)
901F0014            stw       r0,0x14(r31)   ; r0,20(r31)