/*
 * (C) Copyright 2007 Michal Simek
 * (C) Copyright 2004 Atmark Techno, Inc.
 *
 * Michal  SIMEK <monstr@monstr.eu>
 * Yasushi SHOJI <yashi@atmark-techno.com>
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#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    r8, r0, __end
        mts     rslr, r8
        /* TODO: Redo this code to call board_init_f_*() */
#if defined(CONFIG_SPL_BUILD)
        addi    r1, r0, CONFIG_SPL_STACK_ADDR
        mts     rshr, r1
        addi    r1, r1, -4      /* Decrement SP to top of memory */
#else
#if defined(CONFIG_SYS_MALLOC_F_LEN)
        addi    r1, r0, CONFIG_SYS_INIT_SP_OFFSET - CONFIG_SYS_MALLOC_F_LEN
#else
        addi    r1, r0, CONFIG_SYS_INIT_SP_OFFSET
#endif
        mts     rshr, r1
        addi    r1, r1, -4      /* Decrement SP to top of memory */

        /* 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, 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
        /*
         * 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

        /* 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, 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, r10
        rsubi   r8, r10, 0x22
        sh      r7, r0, r8
        rsubi   r8, r10, 0x26
        sh      r6, r0, r8
#endif /* BUILD_SPL */

        /* Flush cache before enable cache */
        addik   r5, r0, 0
        addik   r6, r0, XILINX_DCACHE_BYTE_SIZE
        bralid r15, flush_cache
        nop

        /* enable instruction and data cache */
        mfs     r12, rmsr
        ori     r12, r12, 0x1a0
        mts     rmsr, r12

        /* TODO: Redo this code to call board_init_f_*() */
clear_bss:
        /* clear BSS segments */
        addi    r5, r0, __bss_start
        addi    r4, r0, __bss_end
        cmp     r6, r5, r4
        beqi    r6, 3f
2:
        swi     r0, r5, 0 /* write zero to loc */
        addi    r5, r5, 4 /* increment to next loc */
        cmp     r6, r5, r4 /* check if we have reach the end */
        bnei    r6, 2b
3:      /* jumping to board_init */
#ifdef CONFIG_DEBUG_UART
        bralid  r15, debug_uart_init
        nop
#endif
#ifndef CONFIG_SPL_BUILD
        or      r5, r0, r0      /* flags - empty */
        addi    r31, r0, _gd
#if defined(CONFIG_SYS_MALLOC_F_LEN)
        addi    r6, r0, CONFIG_SYS_INIT_SP_OFFSET
        swi     r6, r31, GD_MALLOC_BASE
#endif
        brai    board_init_f
#else
        addi    r31, r0, _gd
#if defined(CONFIG_SYS_MALLOC_F_LEN)
        addi    r6, r0, CONFIG_SPL_STACK_ADDR
        swi     r6, r31, GD_MALLOC_BASE
#endif
        brai    board_init_r
#endif
1:      bri     1b

 .section .bss
.align 4
_gd:
         .space  GENERATED_GBL_DATA_SIZE

#ifndef CONFIG_SPL_BUILD
/*
 * Read 16bit little endian
 */
        .text
        .global in16
        .ent    in16
        .align  2
in16:   lhu     r3, r0, r5
        bslli   r4, r3, 8
        bsrli   r3, r3, 8
        andi    r4, r4, 0xffff
        or      r3, r3, r4
        rtsd    r15, 8
        sext16  r3, r3
        .end    in16

/*
 * Write 16bit little endian
 * first parameter(r5) - address, second(r6) - short value
 */
        .text
        .global out16
        .ent    out16
        .align  2
out16:  bslli   r3, r6, 8
        bsrli   r6, r6, 8
        andi    r3, r3, 0xffff
        or      r3, r3, r6
        sh      r3, r0, r5
        rtsd    r15, 8
        or      r0, r0, r0
        .end    out16

/*
 * Relocate u-boot
 */
        .text
        .global relocate_code
        .ent    relocate_code
        .align  2
relocate_code:
        /*
         * r5 - start_addr_sp
         * r6 - new_gd
         * r7 - reloc_addr
         */
        addi    r1, r5, 0 /* Start to use new SP */
        addi    r31, r6, 0 /* Start to use new GD */

        add     r23, r0, r7 /* Move reloc addr to r23 */
        /* Relocate text and data - r12 temp value */
        addi    r21, r0, _start
        addi    r22, r0, __end - 4 /* Include BSS too */

        rsub    r6, r21, r22
        or      r5, r0, r0
1:      lw      r12, r21, r5 /* Load u-boot data */
        sw      r12, r23, r5 /* Write zero to loc */
        cmp     r12, r5, r6 /* Check if we have reach the end */
        bneid   r12, 1b
        addi    r5, r5, 4 /* Increment to next loc - relocate code */

       /* R23 points to the base address. */
        add     r23, r0, r7 /* Move reloc addr to r23 */
        addi    r24, r0, CONFIG_SYS_TEXT_BASE /* Get reloc offset */
        rsub    r23, r24, r23 /* keep - this is already here gd->reloc_off */

        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

#ifdef CONFIG_SYS_USR_EXCEP
        addik   r6, r0, _exception_handler
        addk    r6, r6, r23 /* add offset */
        sw      r6, r1, r0
        lhu     r7, r1, r10
        rsubi   r8, r10, 0xa
        sh      r7, r0, r8
        rsubi   r8, r10, 0xe
        sh      r6, r0, r8
#endif
        addik   r6, r0, _hw_exception_handler
        addk    r6, r6, r23 /* add offset */
        sw      r6, r1, r0
        lhu     r7, r1, r10
        rsubi   r8, r10, 0x22
        sh      r7, r0, r8
        rsubi   r8, r10, 0x26
        sh      r6, r0, r8

        addik   r6, r0, _interrupt_handler
        addk    r6, r6, r23 /* add offset */
        sw      r6, r1, r0
        lhu     r7, r1, r10
        rsubi   r8, r10, 0x12
        sh      r7, r0, r8
        rsubi   r8, r10, 0x16
        sh      r6, r0, r8

        /* Check if GOT exist */
        addik   r21, r23, _got_start
        addik   r22, r23, _got_end
        cmpu    r12, r21, r22
        beqi    r12, 2f /* No GOT table - jump over */

        /* Skip last 3 entries plus 1 because of loop boundary below */
        addik   r22, r22, -0x10

        /* Relocate the GOT. */
3:      lw      r12, r21, r0 /* Load entry */
        addk    r12, r12, r23 /* Add reloc offset */
        sw      r12, r21, r0 /* Save entry back */

        cmpu    r12, r21, r22 /* Check if this cross boundary */
        bneid   r12, 3b
        addik   r21. r21, 4

        /* Update pointer to GOT */
        mfs     r20, rpc
        addik   r20, r20, _GLOBAL_OFFSET_TABLE_ + 8
        addk    r20, r20, r23

        /* Flush caches to ensure consistency */
        addik   r5, r0, 0
        addik   r6, r0, XILINX_DCACHE_BYTE_SIZE
        bralid  r15, flush_cache
        nop

2:      addi    r5, r31, 0 /* gd is initialized in board_r.c */
        addi    r6, r0, CONFIG_SYS_TEXT_BASE
        addi    r12, r23, board_init_r
        bra     r12 /* Jump to relocated code */

        .end    relocate_code
#endif