/* * Copyright (C) 2007-2009 Michal Simek * 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 * Initial PowerPC version. * Copyright (c) 1996 Cort Dougan * Rewritten for PReP * Copyright (c) 1996 Paul Mackerras * Low-level exception handers, MMU support, and rewrite. * Copyright (c) 1997 Dan Malek * PowerPC 8xx modifications. * Copyright (c) 1998-1999 TiVo, Inc. * PowerPC 403GCX modifications. * Copyright (c) 1999 Grant Erickson * 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 #include #include #include /* for OF_DT_HEADER */ #ifdef CONFIG_MMU #include /* COMMAND_LINE_SIZE */ #include #include .data .global empty_zero_page .align 12 empty_zero_page: .space 4096 .global swapper_pg_dir swapper_pg_dir: .space 4096 #endif /* CONFIG_MMU */ .text ENTRY(_start) #if CONFIG_KERNEL_BASE_ADDR == 0 brai TOPHYS(real_start) .org 0x100 real_start: #endif mfs r1, rmsr andi r1, r1, ~2 mts rmsr, r1 /* * Here is checking mechanism which check if Microblaze has msr instructions * We load msr and compare it with previous r1 value - if is the same, * msr instructions works if not - cpu don't have them. */ /* r8=0 - I have msr instr, 1 - I don't have them */ rsubi r0, r0, 1 /* set the carry bit */ msrclr r0, 0x4 /* try to clear it */ /* read the carry bit, r8 will be '0' if msrclr exists */ addik r8, r0, 0 /* 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 */ lw r11, r0, r7 /* Does r7 point to a */ rsubi r11, r11, OF_DT_HEADER /* valid FDT? */ 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, (0x4000 - 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 to __init_end. There is space for storing command line. */ or r6, r0, r0 /* incremment */ ori r4, r0, __init_end /* 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: lbu r2, r5, r6 /* r7=r5+r6 - r5 contain pointer to command line */ sb r2, r4, r6 /* addr[r4+r6]= r7*/ addik r6, r6, 1 /* increment counting */ bgtid r3, _copy_command_line /* loop for all entries */ addik r3, r3, -1 /* descrement loop */ addik r5, r4, 0 /* add new space for command line */ tovirt(r5,r5) #endif /* CONFIG_CMDLINE_BOOL */ #ifdef NOT_COMPILE /* save bram context */ or r6, r0, r0 /* incremment */ ori r4, r0, TOPHYS(_bram_load_start) /* save bram context */ ori r3, r0, (LMB_SIZE - 4) _copy_bram: lw r7, r0, r6 /* r7 = r0 + r6 */ sw r7, r4, r6 /* addr[r4 + r6] = r7*/ addik r6, r6, 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, 63 /* Invalidate all TLB entries */ _invalidate: mts rtlbx, r3 mts rtlbhi, r0 /* flush: ensure V is clear */ 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 */ /* * 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 */ andi r3,r3,0xfffffc00 /* Mask off the effective page number */ ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M)) mts rtlbx,r0 /* TLB slow 0 */ mts rtlblo,r4 /* Load the data portion of the entry */ mts rtlbhi,r3 /* Load the tag portion of the entry */ addik r4, r4, 0x01000000 /* Map next 16 M entries */ addik r3, r3, 0x01000000 ori r6,r0,1 /* TLB slot 1 */ mts rtlbx,r6 mts rtlblo,r4 /* Load the data portion of the entry */ mts rtlbhi,r3 /* Load the tag portion of the entry */ /* * Load a TLB entry for LMB, since we need access to * the exception vectors, using a 4k real==virtual mapping. */ ori r6,r0,3 /* TLB slot 3 */ mts rtlbx,r6 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 */ la r13, r0, _KERNEL_SDA_BASE_ la r2, r0, _KERNEL_SDA2_BASE_ /* Initialize stack pointer */ la r1, r0, init_thread_union + THREAD_SIZE - 4 /* Initialize r31 with current task address */ la r31, r0, init_task /* * Call platform dependent initialize function. * Please see $(ARCH)/mach-$(SUBARCH)/setup.c for * the function. */ la r9, r0, machine_early_init brald r15, r9 nop #ifndef CONFIG_MMU la 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: # Keep entry 0 and 1 valid. Entry 3 mapped to LMB can go away. ori r5,r0,3 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 */