| /* |
| * 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, (0x10000 - 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 |
| |
| 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 */ |
