diff options
Diffstat (limited to 'arch/microblaze/kernel/head.S')
| -rw-r--r-- | arch/microblaze/kernel/head.S | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S index 42434008209e..778a5ce2e4fc 100644 --- a/arch/microblaze/kernel/head.S +++ b/arch/microblaze/kernel/head.S @@ -62,23 +62,32 @@ real_start: andi r1, r1, ~2 mts rmsr, r1 /* - * Here is checking mechanism which check if Microblaze has msr instructions - * We load msr and compare it with previous r1 value - if is the same, - * msr instructions works if not - cpu don't have them. + * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc' + * if the msrclr instruction is not enabled. We use this to detect + * if the opcode is available, by issuing msrclr and then testing the result. + * r8 == 0 - msr instructions are implemented + * r8 != 0 - msr instructions are not implemented */ - /* r8=0 - I have msr instr, 1 - I don't have them */ - rsubi r0, r0, 1 /* set the carry bit */ - msrclr r0, 0x4 /* try to clear it */ - /* read the carry bit, r8 will be '0' if msrclr exists */ - addik r8, r0, 0 + msrclr r8, 0 /* clear nothing - just read msr for test */ + cmpu r8, r8, r1 /* r1 must contain msr reg content */ /* r7 may point to an FDT, or there may be one linked in. if it's in r7, we've got to save it away ASAP. We ensure r7 points to a valid FDT, just in case the bootloader is broken or non-existent */ beqi r7, no_fdt_arg /* NULL pointer? don't copy */ - lw r11, r0, r7 /* Does r7 point to a */ - rsubi r11, r11, OF_DT_HEADER /* valid FDT? */ +/* Does r7 point to a valid FDT? Load HEADER magic number */ + /* Run time Big/Little endian platform */ + /* Save 1 as word and load byte - 0 - BIG, 1 - LITTLE */ + addik r11, r0, 0x1 /* BIG/LITTLE checking value */ + /* __bss_start will be zeroed later - it is just temp location */ + swi r11, r0, TOPHYS(__bss_start) + lbui r11, r0, TOPHYS(__bss_start) + beqid r11, big_endian /* DO NOT break delay stop dependency */ + lw r11, r0, r7 /* Big endian load in delay slot */ + lwr r11, r0, r7 /* Little endian load */ +big_endian: + rsubi r11, r11, OF_DT_HEADER /* Check FDT header */ beqi r11, _prepare_copy_fdt or r7, r0, r0 /* clear R7 when not valid DTB */ bnei r11, no_fdt_arg /* No - get out of here */ |