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Diffstat (limited to 'arch/microblaze/kernel/head.S')
| -rw-r--r-- | arch/microblaze/kernel/head.S | 391 |
1 files changed, 391 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S new file mode 100644 index 000000000..4655ff342 --- /dev/null +++ b/arch/microblaze/kernel/head.S @@ -0,0 +1,391 @@ +/* + * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu> + * Copyright (C) 2007-2009 PetaLogix + * Copyright (C) 2006 Atmark Techno, Inc. + * + * MMU code derived from arch/ppc/kernel/head_4xx.S: + * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org> + * Initial PowerPC version. + * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu> + * Rewritten for PReP + * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au> + * Low-level exception handers, MMU support, and rewrite. + * Copyright (c) 1997 Dan Malek <dmalek@jlc.net> + * PowerPC 8xx modifications. + * Copyright (c) 1998-1999 TiVo, Inc. + * PowerPC 403GCX modifications. + * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> + * PowerPC 403GCX/405GP modifications. + * Copyright 2000 MontaVista Software Inc. + * PPC405 modifications + * PowerPC 403GCX/405GP modifications. + * Author: MontaVista Software, Inc. + * frank_rowand@mvista.com or source@mvista.com + * debbie_chu@mvista.com + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include <linux/init.h> +#include <linux/linkage.h> +#include <asm/thread_info.h> +#include <asm/page.h> +#include <linux/of_fdt.h> /* for OF_DT_HEADER */ + +#ifdef CONFIG_MMU +#include <asm/setup.h> /* COMMAND_LINE_SIZE */ +#include <asm/mmu.h> +#include <asm/processor.h> + +.section .data +.global empty_zero_page +.align 12 +empty_zero_page: + .space PAGE_SIZE +.global swapper_pg_dir +swapper_pg_dir: + .space PAGE_SIZE + +#endif /* CONFIG_MMU */ + +.section .rodata +.align 4 +endian_check: + .word 1 + + __HEAD +ENTRY(_start) +#if CONFIG_KERNEL_BASE_ADDR == 0 + brai TOPHYS(real_start) + .org 0x100 +real_start: +#endif + + mts rmsr, r0 +/* Disable stack protection from bootloader */ + mts rslr, r0 + addi r8, r0, 0xFFFFFFFF + mts rshr, r8 +/* + * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc' + * if the msrclr instruction is not enabled. We use this to detect + * if the opcode is available, by issuing msrclr and then testing the result. + * r8 == 0 - msr instructions are implemented + * r8 != 0 - msr instructions are not implemented + */ + mfs r1, rmsr + msrclr r8, 0 /* clear nothing - just read msr for test */ + cmpu r8, r8, r1 /* r1 must contain msr reg content */ + +/* r7 may point to an FDT, or there may be one linked in. + if it's in r7, we've got to save it away ASAP. + We ensure r7 points to a valid FDT, just in case the bootloader + is broken or non-existent */ + beqi r7, no_fdt_arg /* NULL pointer? don't copy */ +/* Does r7 point to a valid FDT? Load HEADER magic number */ + /* Run time Big/Little endian platform */ + /* Save 1 as word and load byte - 0 - BIG, 1 - LITTLE */ + lbui r11, r0, TOPHYS(endian_check) + beqid r11, big_endian /* DO NOT break delay stop dependency */ + lw r11, r0, r7 /* Big endian load in delay slot */ + lwr r11, r0, r7 /* Little endian load */ +big_endian: + rsubi r11, r11, OF_DT_HEADER /* Check FDT header */ + beqi r11, _prepare_copy_fdt + or r7, r0, r0 /* clear R7 when not valid DTB */ + bnei r11, no_fdt_arg /* No - get out of here */ +_prepare_copy_fdt: + or r11, r0, r0 /* incremment */ + ori r4, r0, TOPHYS(_fdt_start) + ori r3, r0, (0x8000 - 4) +_copy_fdt: + lw r12, r7, r11 /* r12 = r7 + r11 */ + sw r12, r4, r11 /* addr[r4 + r11] = r12 */ + addik r11, r11, 4 /* increment counting */ + bgtid r3, _copy_fdt /* loop for all entries */ + addik r3, r3, -4 /* descrement loop */ +no_fdt_arg: + +#ifdef CONFIG_MMU + +#ifndef CONFIG_CMDLINE_BOOL +/* + * handling command line + * copy command line directly to cmd_line placed in data section. + */ + beqid r5, skip /* Skip if NULL pointer */ + or r11, r0, r0 /* incremment */ + ori r4, r0, cmd_line /* load address of command line */ + tophys(r4,r4) /* convert to phys address */ + ori r3, r0, COMMAND_LINE_SIZE - 1 /* number of loops */ +_copy_command_line: + /* r2=r5+r6 - r5 contain pointer to command line */ + lbu r2, r5, r11 + beqid r2, skip /* Skip if no data */ + sb r2, r4, r11 /* addr[r4+r6]= r2 */ + addik r11, r11, 1 /* increment counting */ + bgtid r3, _copy_command_line /* loop for all entries */ + addik r3, r3, -1 /* decrement loop */ + addik r5, r4, 0 /* add new space for command line */ + tovirt(r5,r5) +skip: +#endif /* CONFIG_CMDLINE_BOOL */ + +#ifdef NOT_COMPILE +/* save bram context */ + or r11, r0, r0 /* incremment */ + ori r4, r0, TOPHYS(_bram_load_start) /* save bram context */ + ori r3, r0, (LMB_SIZE - 4) +_copy_bram: + lw r7, r0, r11 /* r7 = r0 + r6 */ + sw r7, r4, r11 /* addr[r4 + r6] = r7 */ + addik r11, r11, 4 /* increment counting */ + bgtid r3, _copy_bram /* loop for all entries */ + addik r3, r3, -4 /* descrement loop */ +#endif + /* We have to turn on the MMU right away. */ + + /* + * Set up the initial MMU state so we can do the first level of + * kernel initialization. This maps the first 16 MBytes of memory 1:1 + * virtual to physical. + */ + nop + addik r3, r0, MICROBLAZE_TLB_SIZE -1 /* Invalidate all TLB entries */ +_invalidate: + mts rtlbx, r3 + mts rtlbhi, r0 /* flush: ensure V is clear */ + mts rtlblo, r0 + bgtid r3, _invalidate /* loop for all entries */ + addik r3, r3, -1 + /* sync */ + + /* Setup the kernel PID */ + mts rpid,r0 /* Load the kernel PID */ + nop + bri 4 + + /* + * We should still be executing code at physical address area + * RAM_BASEADDR at this point. However, kernel code is at + * a virtual address. So, set up a TLB mapping to cover this once + * translation is enabled. + */ + + addik r3,r0, CONFIG_KERNEL_START /* Load the kernel virtual address */ + tophys(r4,r3) /* Load the kernel physical address */ + + /* start to do TLB calculation */ + addik r12, r0, _end + rsub r12, r3, r12 + addik r12, r12, CONFIG_LOWMEM_SIZE >> PTE_SHIFT /* that's the pad */ + + or r9, r0, r0 /* TLB0 = 0 */ + or r10, r0, r0 /* TLB1 = 0 */ + + addik r11, r12, -0x1000000 + bgei r11, GT16 /* size is greater than 16MB */ + addik r11, r12, -0x0800000 + bgei r11, GT8 /* size is greater than 8MB */ + addik r11, r12, -0x0400000 + bgei r11, GT4 /* size is greater than 4MB */ + /* size is less than 4MB */ + addik r11, r12, -0x0200000 + bgei r11, GT2 /* size is greater than 2MB */ + addik r9, r0, 0x0100000 /* TLB0 must be 1MB */ + addik r11, r12, -0x0100000 + bgei r11, GT1 /* size is greater than 1MB */ + /* TLB1 is 0 which is setup above */ + bri tlb_end +GT4: /* r11 contains the rest - will be either 1 or 4 */ + ori r9, r0, 0x400000 /* TLB0 is 4MB */ + bri TLB1 +GT16: /* TLB0 is 16MB */ + addik r9, r0, 0x1000000 /* means TLB0 is 16MB */ +TLB1: + /* must be used r2 because of subtract if failed */ + addik r2, r11, -0x0400000 + bgei r2, GT20 /* size is greater than 16MB */ + /* size is >16MB and <20MB */ + addik r11, r11, -0x0100000 + bgei r11, GT17 /* size is greater than 17MB */ + /* kernel is >16MB and < 17MB */ +GT1: + addik r10, r0, 0x0100000 /* means TLB1 is 1MB */ + bri tlb_end +GT2: /* TLB0 is 0 and TLB1 will be 4MB */ +GT17: /* TLB1 is 4MB - kernel size <20MB */ + addik r10, r0, 0x0400000 /* means TLB1 is 4MB */ + bri tlb_end +GT8: /* TLB0 is still zero that's why I can use only TLB1 */ +GT20: /* TLB1 is 16MB - kernel size >20MB */ + addik r10, r0, 0x1000000 /* means TLB1 is 16MB */ +tlb_end: + + /* + * Configure and load two entries into TLB slots 0 and 1. + * In case we are pinning TLBs, these are reserved in by the + * other TLB functions. If not reserving, then it doesn't + * matter where they are loaded. + */ + andi r4,r4,0xfffffc00 /* Mask off the real page number */ + ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ + + /* + * TLB0 is always used - check if is not zero (r9 stores TLB0 value) + * if is use TLB1 value and clear it (r10 stores TLB1 value) + */ + bnei r9, tlb0_not_zero + add r9, r10, r0 + add r10, r0, r0 +tlb0_not_zero: + + /* look at the code below */ + ori r30, r0, 0x200 + andi r29, r9, 0x100000 + bneid r29, 1f + addik r30, r30, 0x80 + andi r29, r9, 0x400000 + bneid r29, 1f + addik r30, r30, 0x80 + andi r29, r9, 0x1000000 + bneid r29, 1f + addik r30, r30, 0x80 +1: + andi r3,r3,0xfffffc00 /* Mask off the effective page number */ + ori r3,r3,(TLB_VALID) + or r3, r3, r30 + + /* Load tlb_skip size value which is index to first unused TLB entry */ + lwi r11, r0, TOPHYS(tlb_skip) + mts rtlbx,r11 /* TLB slow 0 */ + + mts rtlblo,r4 /* Load the data portion of the entry */ + mts rtlbhi,r3 /* Load the tag portion of the entry */ + + /* Increase tlb_skip size */ + addik r11, r11, 1 + swi r11, r0, TOPHYS(tlb_skip) + + /* TLB1 can be zeroes that's why we not setup it */ + beqi r10, jump_over2 + + /* look at the code below */ + ori r30, r0, 0x200 + andi r29, r10, 0x100000 + bneid r29, 1f + addik r30, r30, 0x80 + andi r29, r10, 0x400000 + bneid r29, 1f + addik r30, r30, 0x80 + andi r29, r10, 0x1000000 + bneid r29, 1f + addik r30, r30, 0x80 +1: + addk r4, r4, r9 /* previous addr + TLB0 size */ + addk r3, r3, r9 + + andi r3,r3,0xfffffc00 /* Mask off the effective page number */ + ori r3,r3,(TLB_VALID) + or r3, r3, r30 + + lwi r11, r0, TOPHYS(tlb_skip) + mts rtlbx, r11 /* r11 is used from TLB0 */ + + mts rtlblo,r4 /* Load the data portion of the entry */ + mts rtlbhi,r3 /* Load the tag portion of the entry */ + + /* Increase tlb_skip size */ + addik r11, r11, 1 + swi r11, r0, TOPHYS(tlb_skip) + +jump_over2: + /* + * Load a TLB entry for LMB, since we need access to + * the exception vectors, using a 4k real==virtual mapping. + */ + /* Use temporary TLB_ID for LMB - clear this temporary mapping later */ + ori r11, r0, MICROBLAZE_LMB_TLB_ID + mts rtlbx,r11 + + ori r4,r0,(TLB_WR | TLB_EX) + ori r3,r0,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K)) + + mts rtlblo,r4 /* Load the data portion of the entry */ + mts rtlbhi,r3 /* Load the tag portion of the entry */ + + /* + * We now have the lower 16 Meg of RAM mapped into TLB entries, and the + * caches ready to work. + */ +turn_on_mmu: + ori r15,r0,start_here + ori r4,r0,MSR_KERNEL_VMS + mts rmsr,r4 + nop + rted r15,0 /* enables MMU */ + nop + +start_here: +#endif /* CONFIG_MMU */ + + /* Initialize small data anchors */ + addik r13, r0, _KERNEL_SDA_BASE_ + addik r2, r0, _KERNEL_SDA2_BASE_ + + /* Initialize stack pointer */ + addik r1, r0, init_thread_union + THREAD_SIZE - 4 + + /* Initialize r31 with current task address */ + addik r31, r0, init_task + + /* + * Call platform dependent initialize function. + * Please see $(ARCH)/mach-$(SUBARCH)/setup.c for + * the function. + */ + addik r11, r0, machine_early_init + brald r15, r11 + nop + +#ifndef CONFIG_MMU + addik r15, r0, machine_halt + braid start_kernel + nop +#else + /* + * Initialize the MMU. + */ + bralid r15, mmu_init + nop + + /* Go back to running unmapped so we can load up new values + * and change to using our exception vectors. + * On the MicroBlaze, all we invalidate the used TLB entries to clear + * the old 16M byte TLB mappings. + */ + ori r15,r0,TOPHYS(kernel_load_context) + ori r4,r0,MSR_KERNEL + mts rmsr,r4 + nop + bri 4 + rted r15,0 + nop + + /* Load up the kernel context */ +kernel_load_context: + ori r5, r0, MICROBLAZE_LMB_TLB_ID + mts rtlbx,r5 + nop + mts rtlbhi,r0 + nop + addi r15, r0, machine_halt + ori r17, r0, start_kernel + ori r4, r0, MSR_KERNEL_VMS + mts rmsr, r4 + nop + rted r17, 0 /* enable MMU and jump to start_kernel */ + nop +#endif /* CONFIG_MMU */ |