2 * Startup Code for MIPS32 CPU-core
4 * Copyright (c) 2003 Wolfgang Denk <wd@denx.de>
6 * SPDX-License-Identifier: GPL-2.0+
9 #include <asm-offsets.h>
11 #include <asm/regdef.h>
12 #include <asm/mipsregs.h>
14 #ifndef CONFIG_SYS_MIPS_CACHE_MODE
15 #define CONFIG_SYS_MIPS_CACHE_MODE CONF_CM_CACHABLE_NONCOHERENT
19 * For the moment disable interrupts, mark the kernel mode and
20 * set ST0_KX so that the CPU does not spit fire when using
23 .macro setup_c0_status set clr
26 or t0, ST0_CU0 | \set | 0x1f | \clr
39 /* U-boot entry point */
44 #ifdef CONFIG_SYS_XWAY_EBU_BOOTCFG
46 * Almost all Lantiq XWAY SoC devices have an external bus unit (EBU) to
47 * access external NOR flashes. If the board boots from NOR flash the
48 * internal BootROM does a blind read at address 0xB0000010 to read the
49 * initial configuration for that EBU in order to access the flash
50 * device with correct parameters. This config option is board-specific.
52 .word CONFIG_SYS_XWAY_EBU_BOOTCFG
57 /* TLB refill, 32 bit task */
62 /* XTLB refill, 64 bit task */
67 /* Cache error exception */
72 /* General exception */
77 /* Catch interrupt exceptions */
82 /* EJTAG debug exception */
89 /* Clear watch registers */
90 mtc0 zero, CP0_WATCHLO
91 mtc0 zero, CP0_WATCHHI
93 /* WP(Watch Pending), SW0/1 should be cleared */
100 mtc0 zero, CP0_COMPARE
102 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
103 /* CONFIG0 register */
104 li t0, CONF_CM_UNCACHED
115 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
116 /* Initialize any external memory */
121 /* Initialize caches... */
122 la t9, mips_cache_reset
126 /* ... and enable them */
127 li t0, CONFIG_SYS_MIPS_CACHE_MODE
131 /* Set up temporary stack */
132 li sp, CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_INIT_SP_OFFSET
139 * void relocate_code (addr_sp, gd, addr_moni)
141 * This "function" does not return, instead it continues in RAM
142 * after relocating the monitor code.
146 * a2 = destination address
151 move sp, a0 # set new stack pointer
153 move s0, a1 # save gd in s0
154 move s2, a2 # save destination address in s2
156 li t0, CONFIG_SYS_MONITOR_BASE
157 sub s1, s2, t0 # s1 <-- relocation offset
160 lw t2, -12(t3) # t2 <-- __image_copy_end
163 add gp, s1 # adjust gp
166 * t0 = source address
167 * t1 = target address
168 * t2 = source end address
177 /* If caches were enabled, we would have to flush them here. */
178 sub a1, t1, s2 # a1 <-- size
181 move a0, s2 # a0 <-- destination address
183 /* Jump to where we've relocated ourselves */
184 addi t0, s2, in_ram - _start
189 .word __rel_dyn_start
190 .word __image_copy_end
191 .word _GLOBAL_OFFSET_TABLE_
192 .word num_got_entries
196 * Now we want to update GOT.
198 * GOT[0] is reserved. GOT[1] is also reserved for the dynamic object
199 * generated by GNU ld. Skip these reserved entries from relocation.
201 lw t3, -4(t0) # t3 <-- num_got_entries
202 lw t4, -8(t0) # t4 <-- _GLOBAL_OFFSET_TABLE_
203 add t4, s1 # t4 now holds relocated _G_O_T_
204 addi t4, t4, 8 # skipping first two entries
216 /* Update dynamic relocations */
217 lw t1, -16(t0) # t1 <-- __rel_dyn_start
218 lw t2, -20(t0) # t2 <-- __rel_dyn_end
220 b 2f # skip first reserved entry
224 lw t3, -4(t1) # t3 <-- relocation info
227 bnez t3, 2f # skip non R_MIPS_REL32 entries
230 lw t3, -8(t1) # t3 <-- location to fix up in FLASH
232 lw t4, 0(t3) # t4 <-- original pointer
233 add t4, s1 # t4 <-- adjusted pointer
235 add t3, s1 # t3 <-- location to fix up in RAM
240 addi t1, 8 # each rel.dyn entry is 8 bytes
245 * GOT is now relocated. Thus __bss_start and __bss_end can be
246 * accessed directly via $gp.
248 la t1, __bss_start # t1 <-- __bss_start
249 la t2, __bss_end # t2 <-- __bss_end
256 move a0, s0 # a0 <-- gd