diff options
Diffstat (limited to 'arch/nds32/kernel/head.S')
| -rw-r--r-- | arch/nds32/kernel/head.S | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/arch/nds32/kernel/head.S b/arch/nds32/kernel/head.S new file mode 100644 index 000000000000..71f57bd70f3b --- /dev/null +++ b/arch/nds32/kernel/head.S @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2005-2017 Andes Technology Corporation + +#include <linux/linkage.h> +#include <linux/init.h> +#include <asm/ptrace.h> +#include <asm/asm-offsets.h> +#include <asm/page.h> +#include <asm/pgtable.h> +#include <asm/sizes.h> +#include <asm/thread_info.h> + +#ifdef CONFIG_CPU_BIG_ENDIAN +#define OF_DT_MAGIC 0xd00dfeed +#else +#define OF_DT_MAGIC 0xedfe0dd0 +#endif + + .globl swapper_pg_dir + .equ swapper_pg_dir, TEXTADDR - 0x4000 + +/* + * Kernel startup entry point. + */ + .section ".head.text", "ax" + .type _stext, %function +ENTRY(_stext) + setgie.d ! Disable interrupt + isb +/* + * Disable I/D-cache and enable it at a proper time + */ + mfsr $r0, $mr8 + li $r1, #~(CACHE_CTL_mskIC_EN|CACHE_CTL_mskDC_EN) + and $r0, $r0, $r1 + mtsr $r0, $mr8 + +/* + * Process device tree blob + */ + andi $r0,$r2,#0x3 + li $r10, 0 + bne $r0, $r10, _nodtb + lwi $r0, [$r2] + li $r1, OF_DT_MAGIC + bne $r0, $r1, _nodtb + move $r10, $r2 +_nodtb: + +/* + * Create a temporary mapping area for booting, before start_kernel + */ + sethi $r4, hi20(swapper_pg_dir) + li $p0, (PAGE_OFFSET - PHYS_OFFSET) + sub $r4, $r4, $p0 + tlbop FlushAll ! invalidate TLB\n" + isb + mtsr $r4, $L1_PPTB ! load page table pointer\n" + +/* set NTC0 cacheable/writeback, mutliple page size in use */ + mfsr $r3, $MMU_CTL + li $r0, #~MMU_CTL_mskNTC0 + and $r3, $r3, $r0 +#ifdef CONFIG_ANDES_PAGE_SIZE_4KB + ori $r3, $r3, #(MMU_CTL_mskMPZIU|(MMU_CTL_CACHEABLE_WB << MMU_CTL_offNTC0)) +#else + ori $r3, $r3, #(MMU_CTL_mskMPZIU|(MMU_CTL_CACHEABLE_WB << MMU_CTL_offNTC0)|MMU_CTL_D8KB) +#endif +#ifdef CONFIG_HW_SUPPORT_UNALIGNMENT_ACCESS + li $r0, #MMU_CTL_UNA + or $r3, $r3, $r0 +#endif + mtsr $r3, $MMU_CTL + isb + +/* set page size and size of kernel image */ + mfsr $r0, $MMU_CFG + srli $r3, $r0, MMU_CFG_offfEPSZ + zeb $r3, $r3 + bnez $r3, _extra_page_size_support +#ifdef CONFIG_ANDES_PAGE_SIZE_4KB + li $r5, #SZ_4K ! Use 4KB page size +#else + li $r5, #SZ_8K ! Use 8KB page size + li $r3, #1 +#endif + mtsr $r3, $TLB_MISC + b _image_size_check + +_extra_page_size_support: ! Use epzs pages size + clz $r6, $r3 + subri $r2, $r6, #31 + li $r3, #1 + sll $r3, $r3, $r2 + /* MMU_CFG.EPSZ value -> meaning */ + mul $r5, $r3, $r3 + slli $r5, $r5, #14 + /* MMU_CFG.EPSZ -> TLB_MISC.ACC_PSZ */ + addi $r3, $r2, #0x2 + mtsr $r3, $TLB_MISC + +_image_size_check: + /* calculate the image maximum size accepted by TLB config */ + andi $r6, $r0, MMU_CFG_mskTBW + andi $r0, $r0, MMU_CFG_mskTBS + srli $r6, $r6, MMU_CFG_offTBW + srli $r0, $r0, MMU_CFG_offTBS + /* + * we just map the kernel to the maximum way - 1 of tlb + * reserver one way for UART VA mapping + * it will cause page fault if UART mapping cover the kernel mapping + * + * direct mapping is not supported now. + */ + li $r2, 't' + beqz $r6, __error ! MMU_CFG.TBW = 0 is direct mappin + addi $r0, $r0, #0x2 ! MMU_CFG.TBS value -> meaning + sll $r0, $r6, $r0 ! entries = k-way * n-set + mul $r6, $r0, $r5 ! max size = entries * page size + /* check kernel image size */ + la $r3, (_end - PAGE_OFFSET) + li $r2, 's' + bgt $r3, $r6, __error + + li $r2, #(PHYS_OFFSET + TLB_DATA_kernel_text_attr) + li $r3, PAGE_OFFSET + add $r6, $r6, $r3 + +_tlb: + mtsr $r3, $TLB_VPN + dsb + tlbop $r2, RWR + isb + add $r3, $r3, $r5 + add $r2, $r2, $r5 + bgt $r6, $r3, _tlb + mfsr $r3, $TLB_MISC ! setup access page size + li $r2, #~0xf + and $r3, $r3, $r2 +#ifdef CONFIG_ANDES_PAGE_SIZE_8KB + ori $r3, $r3, #0x1 +#endif + mtsr $r3, $TLB_MISC + + mfsr $r0, $MISC_CTL ! Enable BTB and RTP and shadow sp + ori $r0, $r0, #MISC_init + mtsr $r0, $MISC_CTL + + mfsr $p1, $PSW + li $r15, #~PSW_clr ! clear WBNA|DME|IME|DT|IT|POM|INTL|GIE + and $p1, $p1, $r15 + ori $p1, $p1, #PSW_init + mtsr $p1, $IPSW ! when iret, it will automatically enable MMU + la $lp, __mmap_switched + mtsr $lp, $IPC + iret + nop + + .type __switch_data, %object +__switch_data: + .long __bss_start ! $r6 + .long _end ! $r7 + .long __atags_pointer ! $atag_pointer + .long init_task ! $r9, move to $r25 + .long init_thread_union + THREAD_SIZE ! $sp + + +/* + * The following fragment of code is executed with the MMU on in MMU mode, + * and uses absolute addresses; this is not position independent. + */ + .align + .type __mmap_switched, %function +__mmap_switched: + la $r3, __switch_data + lmw.bim $r6, [$r3], $r9, #0b0001 + move $r25, $r9 + move $fp, #0 ! Clear BSS (and zero $fp) + beq $r7, $r6, _RRT +1: swi.bi $fp, [$r6], #4 + bne $r7, $r6, 1b + swi $r10, [$r8] + +_RRT: + b start_kernel + +__error: + b __error |