* MA 02111-1307 USA
*/
+#include <asm-offsets.h>
#include <config.h>
.text
.global _start
_start:
+ /*
+ * reserve registers:
+ * r10: Stores little/big endian offset for vectors
+ * r2: Stores imm opcode
+ * r3: Stores brai opcode
+ */
+
mts rmsr, r0 /* disable cache */
addi r1, r0, CONFIG_SYS_INIT_SP_OFFSET
addi r1, r1, -4 /* Decrement SP to top of memory */
- /* add opcode instruction for 32bit jump - 2 instruction imm & brai*/
- addi r6, r0, 0xb0000000 /* hex b000 opcode imm */
- swi r6, r0, 0x0 /* reset address */
- swi r6, r0, 0x8 /* user vector exception */
- swi r6, r0, 0x10 /* interrupt */
- swi r6, r0, 0x20 /* hardware exception */
-
- addi r6, r0, 0xb8080000 /* hew b808 opcode brai*/
- swi r6, r0, 0x4 /* reset address */
- swi r6, r0, 0xC /* user vector exception */
- swi r6, r0, 0x14 /* interrupt */
- swi r6, r0, 0x24 /* hardware exception */
+
+ /* Find-out if u-boot is running on BIG/LITTLE endian platform
+ * There are some steps which is necessary to keep in mind:
+ * 1. Setup offset value to r6
+ * 2. Store word offset value to address 0x0
+ * 3. Load just byte from address 0x0
+ * 4a) LITTLE endian - r10 contains 0x2 because it is the smallest
+ * value that's why is on address 0x0
+ * 4b) BIG endian - r10 contains 0x0 because 0x2 offset is on addr 0x3
+ */
+ addik r6, r0, 0x2 /* BIG/LITTLE endian offset */
+ lwi r7, r0, 0x28
+ swi r6, r0, 0x28 /* used first unused MB vector */
+ lbui r10, r0, 0x28 /* used first unused MB vector */
+ swi r7, r0, 0x28
+
+ /* add opcode instruction for 32bit jump - 2 instruction imm & brai */
+ addi r2, r0, 0xb0000000 /* hex b000 opcode imm */
+ addi r3, r0, 0xb8080000 /* hew b808 opcode brai */
#ifdef CONFIG_SYS_RESET_ADDRESS
/* reset address */
+ swi r2, r0, 0x0 /* reset address - imm opcode */
+ swi r3, r0, 0x4 /* reset address - brai opcode */
+
addik r6, r0, CONFIG_SYS_RESET_ADDRESS
sw r6, r1, r0
- lhu r7, r1, r0
- shi r7, r0, 0x2
- shi r6, r0, 0x6
-/*
- * Copy U-Boot code to TEXT_BASE
- * solve problem with sbrk_base
- */
-#if (CONFIG_SYS_RESET_ADDRESS != TEXT_BASE)
- addi r4, r0, __end
- addi r5, r0, __text_start
- rsub r4, r5, r4 /* size = __end - __text_start */
- addi r6, r0, CONFIG_SYS_RESET_ADDRESS /* source address */
- addi r7, r0, 0 /* counter */
-4:
- lw r8, r6, r7
- sw r8, r5, r7
- addi r7, r7, 0x4
- cmp r8, r4, r7
- blti r8, 4b
-#endif
+ lhu r7, r1, r10
+ rsubi r8, r10, 0x2
+ sh r7, r0, r8
+ rsubi r8, r10, 0x6
+ sh r6, r0, r8
#endif
#ifdef CONFIG_SYS_USR_EXCEP
/* user_vector_exception */
+ swi r2, r0, 0x8 /* user vector exception - imm opcode */
+ swi r3, r0, 0xC /* user vector exception - brai opcode */
+
addik r6, r0, _exception_handler
sw r6, r1, r0
- lhu r7, r1, r0
- shi r7, r0, 0xa
- shi r6, r0, 0xe
+ /*
+ * BIG ENDIAN memory map for user exception
+ * 0x8: 0xB000XXXX
+ * 0xC: 0xB808XXXX
+ *
+ * then it is necessary to count address for storing the most significant
+ * 16bits from _exception_handler address and copy it to
+ * 0xa address. Big endian use offset in r10=0 that's why is it just
+ * 0xa address. The same is done for the least significant 16 bits
+ * for 0xe address.
+ *
+ * LITTLE ENDIAN memory map for user exception
+ * 0x8: 0xXXXX00B0
+ * 0xC: 0xXXXX08B8
+ *
+ * Offset is for little endian setup to 0x2. rsubi instruction decrease
+ * address value to ensure that points to proper place which is
+ * 0x8 for the most significant 16 bits and
+ * 0xC for the least significant 16 bits
+ */
+ lhu r7, r1, r10
+ rsubi r8, r10, 0xa
+ sh r7, r0, r8
+ rsubi r8, r10, 0xe
+ sh r6, r0, r8
#endif
-#ifdef CONFIG_SYS_INTC_0
/* interrupt_handler */
+ swi r2, r0, 0x10 /* interrupt - imm opcode */
+ swi r3, r0, 0x14 /* interrupt - brai opcode */
+
addik r6, r0, _interrupt_handler
sw r6, r1, r0
- lhu r7, r1, r0
- shi r7, r0, 0x12
- shi r6, r0, 0x16
-#endif
+ lhu r7, r1, r10
+ rsubi r8, r10, 0x12
+ sh r7, r0, r8
+ rsubi r8, r10, 0x16
+ sh r6, r0, r8
/* hardware exception */
+ swi r2, r0, 0x20 /* hardware exception - imm opcode */
+ swi r3, r0, 0x24 /* hardware exception - brai opcode */
+
addik r6, r0, _hw_exception_handler
sw r6, r1, r0
- lhu r7, r1, r0
- shi r7, r0, 0x22
- shi r6, r0, 0x26
+ lhu r7, r1, r10
+ rsubi r8, r10, 0x22
+ sh r7, r0, r8
+ rsubi r8, r10, 0x26
+ sh r6, r0, r8
+
+ /* Flush cache before enable cache */
+ addik r5, r0, 0
+ addik r6, r0, XILINX_DCACHE_BYTE_SIZE
+flush: bralid r15, flush_cache
+ nop
/* enable instruction and data cache */
mfs r12, rmsr
cmp r6, r5, r4 /* check if we have reach the end */
bnei r6, 2b
3: /* jumping to board_init */
- brai board_init
+ brai board_init_f
1: bri 1b
/*
projects / oweals / u-boot.git / blobdiff