u-boot/arch/mips/cpu/start.S
Daniel Schwierzeck 924ad86638 MIPS: add possibility to setup initial stack and global data in SRAM
This adds a new Kconfig option CONFIG_MIPS_INIT_STACK_IN_SRAM which
a SoC can select if it supports some kind of SRAM. Together with
CONFIG_SYS_INIT_SP_ADDR the initial stack and global data can be
set up in that SRAM. This can be used to provide a C environment
also for lowlevel_init().

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
2016-11-30 16:11:46 +01:00

392 lines
7.9 KiB
ArmAsm

/*
* Startup Code for MIPS32 CPU-core
*
* Copyright (c) 2003 Wolfgang Denk <wd@denx.de>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <asm/asm.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#ifndef CONFIG_SYS_INIT_SP_ADDR
#define CONFIG_SYS_INIT_SP_ADDR (CONFIG_SYS_SDRAM_BASE + \
CONFIG_SYS_INIT_SP_OFFSET)
#endif
#ifdef CONFIG_32BIT
# define MIPS_RELOC 3
# define STATUS_SET 0
#endif
#ifdef CONFIG_64BIT
# ifdef CONFIG_SYS_LITTLE_ENDIAN
# define MIPS64_R_INFO(ssym, r_type3, r_type2, r_type) \
(((r_type) << 24) | ((r_type2) << 16) | ((r_type3) << 8) | (ssym))
# else
# define MIPS64_R_INFO(ssym, r_type3, r_type2, r_type) \
((r_type) | ((r_type2) << 8) | ((r_type3) << 16) | (ssym) << 24)
# endif
# define MIPS_RELOC MIPS64_R_INFO(0x00, 0x00, 0x12, 0x03)
# define STATUS_SET ST0_KX
#endif
.set noreorder
.macro init_wr sel
MTC0 zero, CP0_WATCHLO,\sel
mtc0 t1, CP0_WATCHHI,\sel
mfc0 t0, CP0_WATCHHI,\sel
bgez t0, wr_done
nop
.endm
.macro uhi_mips_exception
move k0, t9 # preserve t9 in k0
move k1, a0 # preserve a0 in k1
li t9, 15 # UHI exception operation
li a0, 0 # Use hard register context
sdbbp 1 # Invoke UHI operation
.endm
.macro setup_stack_gd
li t0, -16
PTR_LI t1, CONFIG_SYS_INIT_SP_ADDR
and sp, t1, t0 # force 16 byte alignment
PTR_SUBU \
sp, sp, GD_SIZE # reserve space for gd
and sp, sp, t0 # force 16 byte alignment
move k0, sp # save gd pointer
#ifdef CONFIG_SYS_MALLOC_F_LEN
li t2, CONFIG_SYS_MALLOC_F_LEN
PTR_SUBU \
sp, sp, t2 # reserve space for early malloc
and sp, sp, t0 # force 16 byte alignment
#endif
move fp, sp
/* Clear gd */
move t0, k0
1:
PTR_S zero, 0(t0)
blt t0, t1, 1b
PTR_ADDIU t0, PTRSIZE
#ifdef CONFIG_SYS_MALLOC_F_LEN
PTR_S sp, GD_MALLOC_BASE(k0) # gd->malloc_base offset
#endif
.endm
ENTRY(_start)
/* U-Boot entry point */
b reset
mtc0 zero, CP0_COUNT # clear cp0 count for most accurate boot timing
#if defined(CONFIG_SYS_XWAY_EBU_BOOTCFG)
/*
* Almost all Lantiq XWAY SoC devices have an external bus unit (EBU) to
* access external NOR flashes. If the board boots from NOR flash the
* internal BootROM does a blind read at address 0xB0000010 to read the
* initial configuration for that EBU in order to access the flash
* device with correct parameters. This config option is board-specific.
*/
.org 0x10
.word CONFIG_SYS_XWAY_EBU_BOOTCFG
.word 0x0
#endif
#if defined(CONFIG_MALTA)
/*
* Linux expects the Board ID here.
*/
.org 0x10
.word 0x00000420 # 0x420 (Malta Board with CoreLV)
.word 0x00000000
#endif
#if defined(CONFIG_ROM_EXCEPTION_VECTORS)
/*
* Exception vector entry points. When running from ROM, an exception
* cannot be handled. Halt execution and transfer control to debugger,
* if one is attached.
*/
.org 0x200
/* TLB refill, 32 bit task */
uhi_mips_exception
.org 0x280
/* XTLB refill, 64 bit task */
uhi_mips_exception
.org 0x300
/* Cache error exception */
uhi_mips_exception
.org 0x380
/* General exception */
uhi_mips_exception
.org 0x400
/* Catch interrupt exceptions */
uhi_mips_exception
.org 0x480
/* EJTAG debug exception */
1: b 1b
nop
.org 0x500
#endif
reset:
#if __mips_isa_rev >= 6
mfc0 t0, CP0_CONFIG, 5
and t0, t0, MIPS_CONF5_VP
beqz t0, 1f
nop
b 2f
mfc0 t0, CP0_GLOBALNUMBER
#endif
1: mfc0 t0, CP0_EBASE
and t0, t0, EBASE_CPUNUM
/* Hang if this isn't the first CPU in the system */
2: beqz t0, 4f
nop
3: wait
b 3b
nop
/* Init CP0 Status */
4: mfc0 t0, CP0_STATUS
and t0, ST0_IMPL
or t0, ST0_BEV | ST0_ERL | STATUS_SET
mtc0 t0, CP0_STATUS
/*
* Check whether CP0 Config1 is implemented. If not continue
* with legacy Watch register initialization.
*/
mfc0 t0, CP0_CONFIG
bgez t0, wr_legacy
nop
/*
* Check WR bit in CP0 Config1 to determine if Watch registers
* are implemented.
*/
mfc0 t0, CP0_CONFIG, 1
andi t0, (1 << 3)
beqz t0, wr_done
nop
/* Clear Watch Status bits and disable watch exceptions */
li t1, 0x7 # Clear I, R and W conditions
init_wr 0
init_wr 1
init_wr 2
init_wr 3
init_wr 4
init_wr 5
init_wr 6
init_wr 7
b wr_done
nop
wr_legacy:
MTC0 zero, CP0_WATCHLO
mtc0 zero, CP0_WATCHHI
wr_done:
/* Clear WP, IV and SW interrupts */
mtc0 zero, CP0_CAUSE
/* Clear timer interrupt (CP0_COUNT cleared on branch to 'reset') */
mtc0 zero, CP0_COMPARE
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
mfc0 t0, CP0_CONFIG
and t0, t0, MIPS_CONF_IMPL
or t0, t0, CONF_CM_UNCACHED
mtc0 t0, CP0_CONFIG
ehb
#endif
/*
* Initialize $gp, force pointer sized alignment of bal instruction to
* forbid the compiler to put nop's between bal and _gp. This is
* required to keep _gp and ra aligned to 8 byte.
*/
.align PTRLOG
bal 1f
nop
PTR _gp
1:
PTR_L gp, 0(ra)
#ifdef CONFIG_MIPS_CM
PTR_LA t9, mips_cm_map
jalr t9
nop
#endif
#ifdef CONFIG_MIPS_INIT_STACK_IN_SRAM
/* Set up initial stack and global data */
setup_stack_gd
#endif
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
# ifdef CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD
/* Initialize any external memory */
PTR_LA t9, lowlevel_init
jalr t9
nop
# endif
/* Initialize caches... */
PTR_LA t9, mips_cache_reset
jalr t9
nop
# ifndef CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD
/* Initialize any external memory */
PTR_LA t9, lowlevel_init
jalr t9
nop
# endif
#endif
#ifndef CONFIG_MIPS_INIT_STACK_IN_SRAM
/* Set up initial stack and global data */
setup_stack_gd
#endif
move a0, zero # a0 <-- boot_flags = 0
PTR_LA t9, board_init_f
jr t9
move ra, zero
END(_start)
/*
* void relocate_code (addr_sp, gd, addr_moni)
*
* This "function" does not return, instead it continues in RAM
* after relocating the monitor code.
*
* a0 = addr_sp
* a1 = gd
* a2 = destination address
*/
ENTRY(relocate_code)
move sp, a0 # set new stack pointer
move fp, sp
move s0, a1 # save gd in s0
move s2, a2 # save destination address in s2
PTR_LI t0, CONFIG_SYS_MONITOR_BASE
PTR_SUB s1, s2, t0 # s1 <-- relocation offset
PTR_LA t2, __image_copy_end
move t1, a2
/*
* t0 = source address
* t1 = target address
* t2 = source end address
*/
1:
PTR_L t3, 0(t0)
PTR_S t3, 0(t1)
PTR_ADDU t0, PTRSIZE
blt t0, t2, 1b
PTR_ADDU t1, PTRSIZE
/*
* Now we want to update GOT.
*
* GOT[0] is reserved. GOT[1] is also reserved for the dynamic object
* generated by GNU ld. Skip these reserved entries from relocation.
*/
PTR_LA t3, num_got_entries
PTR_LA t8, _GLOBAL_OFFSET_TABLE_
PTR_ADD t8, s1 # t8 now holds relocated _G_O_T_
PTR_ADDIU t8, t8, 2 * PTRSIZE # skipping first two entries
PTR_LI t2, 2
1:
PTR_L t1, 0(t8)
beqz t1, 2f
PTR_ADD t1, s1
PTR_S t1, 0(t8)
2:
PTR_ADDIU t2, 1
blt t2, t3, 1b
PTR_ADDIU t8, PTRSIZE
/* Update dynamic relocations */
PTR_LA t1, __rel_dyn_start
PTR_LA t2, __rel_dyn_end
b 2f # skip first reserved entry
PTR_ADDIU t1, 2 * PTRSIZE
1:
lw t8, -4(t1) # t8 <-- relocation info
PTR_LI t3, MIPS_RELOC
bne t8, t3, 2f # skip non-MIPS_RELOC entries
nop
PTR_L t3, -(2 * PTRSIZE)(t1) # t3 <-- location to fix up in FLASH
PTR_L t8, 0(t3) # t8 <-- original pointer
PTR_ADD t8, s1 # t8 <-- adjusted pointer
PTR_ADD t3, s1 # t3 <-- location to fix up in RAM
PTR_S t8, 0(t3)
2:
blt t1, t2, 1b
PTR_ADDIU t1, 2 * PTRSIZE # each rel.dyn entry is 2*PTRSIZE bytes
/*
* Flush caches to ensure our newly modified instructions are visible
* to the instruction cache. We're still running with the old GOT, so
* apply the reloc offset to the start address.
*/
PTR_LA a0, __text_start
PTR_LA a1, __text_end
PTR_SUB a1, a1, a0
PTR_LA t9, flush_cache
jalr t9
PTR_ADD a0, s1
PTR_ADD gp, s1 # adjust gp
/*
* Clear BSS
*
* GOT is now relocated. Thus __bss_start and __bss_end can be
* accessed directly via $gp.
*/
PTR_LA t1, __bss_start # t1 <-- __bss_start
PTR_LA t2, __bss_end # t2 <-- __bss_end
1:
PTR_S zero, 0(t1)
blt t1, t2, 1b
PTR_ADDIU t1, PTRSIZE
move a0, s0 # a0 <-- gd
move a1, s2
PTR_LA t9, board_init_r
jr t9
move ra, zero
END(relocate_code)