diff options
Diffstat (limited to 'arch/powerpc/kernel/head_8xx.S')
| -rw-r--r-- | arch/powerpc/kernel/head_8xx.S | 860 |
1 files changed, 860 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S new file mode 100644 index 00000000000..cb1a3a54a02 --- /dev/null +++ b/arch/powerpc/kernel/head_8xx.S @@ -0,0 +1,860 @@ +/* + * arch/ppc/kernel/except_8xx.S + * + * PowerPC version + * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) + * Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP + * Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu> + * Low-level exception handlers and MMU support + * rewritten by Paul Mackerras. + * Copyright (C) 1996 Paul Mackerras. + * MPC8xx modifications by Dan Malek + * Copyright (C) 1997 Dan Malek (dmalek@jlc.net). + * + * This file contains low-level support and setup for PowerPC 8xx + * embedded processors, including trap and interrupt dispatch. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + */ + +#include <linux/config.h> +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/mmu.h> +#include <asm/cache.h> +#include <asm/pgtable.h> +#include <asm/cputable.h> +#include <asm/thread_info.h> +#include <asm/ppc_asm.h> +#include <asm/asm-offsets.h> + +/* Macro to make the code more readable. */ +#ifdef CONFIG_8xx_CPU6 +#define DO_8xx_CPU6(val, reg) \ + li reg, val; \ + stw reg, 12(r0); \ + lwz reg, 12(r0); +#else +#define DO_8xx_CPU6(val, reg) +#endif + .text + .globl _stext +_stext: + .text + .globl _start +_start: + +/* MPC8xx + * This port was done on an MBX board with an 860. Right now I only + * support an ELF compressed (zImage) boot from EPPC-Bug because the + * code there loads up some registers before calling us: + * r3: ptr to board info data + * r4: initrd_start or if no initrd then 0 + * r5: initrd_end - unused if r4 is 0 + * r6: Start of command line string + * r7: End of command line string + * + * I decided to use conditional compilation instead of checking PVR and + * adding more processor specific branches around code I don't need. + * Since this is an embedded processor, I also appreciate any memory + * savings I can get. + * + * The MPC8xx does not have any BATs, but it supports large page sizes. + * We first initialize the MMU to support 8M byte pages, then load one + * entry into each of the instruction and data TLBs to map the first + * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to + * the "internal" processor registers before MMU_init is called. + * + * The TLB code currently contains a major hack. Since I use the condition + * code register, I have to save and restore it. I am out of registers, so + * I just store it in memory location 0 (the TLB handlers are not reentrant). + * To avoid making any decisions, I need to use the "segment" valid bit + * in the first level table, but that would require many changes to the + * Linux page directory/table functions that I don't want to do right now. + * + * I used to use SPRG2 for a temporary register in the TLB handler, but it + * has since been put to other uses. I now use a hack to save a register + * and the CCR at memory location 0.....Someday I'll fix this..... + * -- Dan + */ + .globl __start +__start: + mr r31,r3 /* save parameters */ + mr r30,r4 + mr r29,r5 + mr r28,r6 + mr r27,r7 + + /* We have to turn on the MMU right away so we get cache modes + * set correctly. + */ + bl initial_mmu + +/* We now have the lower 8 Meg mapped into TLB entries, and the caches + * ready to work. + */ + +turn_on_mmu: + mfmsr r0 + ori r0,r0,MSR_DR|MSR_IR + mtspr SPRN_SRR1,r0 + lis r0,start_here@h + ori r0,r0,start_here@l + mtspr SPRN_SRR0,r0 + SYNC + rfi /* enables MMU */ + +/* + * Exception entry code. This code runs with address translation + * turned off, i.e. using physical addresses. + * We assume sprg3 has the physical address of the current + * task's thread_struct. + */ +#define EXCEPTION_PROLOG \ + mtspr SPRN_SPRG0,r10; \ + mtspr SPRN_SPRG1,r11; \ + mfcr r10; \ + EXCEPTION_PROLOG_1; \ + EXCEPTION_PROLOG_2 + +#define EXCEPTION_PROLOG_1 \ + mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \ + andi. r11,r11,MSR_PR; \ + tophys(r11,r1); /* use tophys(r1) if kernel */ \ + beq 1f; \ + mfspr r11,SPRN_SPRG3; \ + lwz r11,THREAD_INFO-THREAD(r11); \ + addi r11,r11,THREAD_SIZE; \ + tophys(r11,r11); \ +1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */ + + +#define EXCEPTION_PROLOG_2 \ + CLR_TOP32(r11); \ + stw r10,_CCR(r11); /* save registers */ \ + stw r12,GPR12(r11); \ + stw r9,GPR9(r11); \ + mfspr r10,SPRN_SPRG0; \ + stw r10,GPR10(r11); \ + mfspr r12,SPRN_SPRG1; \ + stw r12,GPR11(r11); \ + mflr r10; \ + stw r10,_LINK(r11); \ + mfspr r12,SPRN_SRR0; \ + mfspr r9,SPRN_SRR1; \ + stw r1,GPR1(r11); \ + stw r1,0(r11); \ + tovirt(r1,r11); /* set new kernel sp */ \ + li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \ + MTMSRD(r10); /* (except for mach check in rtas) */ \ + stw r0,GPR0(r11); \ + SAVE_4GPRS(3, r11); \ + SAVE_2GPRS(7, r11) + +/* + * Note: code which follows this uses cr0.eq (set if from kernel), + * r11, r12 (SRR0), and r9 (SRR1). + * + * Note2: once we have set r1 we are in a position to take exceptions + * again, and we could thus set MSR:RI at that point. + */ + +/* + * Exception vectors. + */ +#define EXCEPTION(n, label, hdlr, xfer) \ + . = n; \ +label: \ + EXCEPTION_PROLOG; \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + xfer(n, hdlr) + +#define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \ + li r10,trap; \ + stw r10,TRAP(r11); \ + li r10,MSR_KERNEL; \ + copyee(r10, r9); \ + bl tfer; \ +i##n: \ + .long hdlr; \ + .long ret + +#define COPY_EE(d, s) rlwimi d,s,0,16,16 +#define NOCOPY(d, s) + +#define EXC_XFER_STD(n, hdlr) \ + EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \ + ret_from_except_full) + +#define EXC_XFER_LITE(n, hdlr) \ + EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \ + ret_from_except) + +#define EXC_XFER_EE(n, hdlr) \ + EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \ + ret_from_except_full) + +#define EXC_XFER_EE_LITE(n, hdlr) \ + EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \ + ret_from_except) + +/* System reset */ + EXCEPTION(0x100, Reset, UnknownException, EXC_XFER_STD) + +/* Machine check */ + . = 0x200 +MachineCheck: + EXCEPTION_PROLOG + mfspr r4,SPRN_DAR + stw r4,_DAR(r11) + mfspr r5,SPRN_DSISR + stw r5,_DSISR(r11) + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_STD(0x200, MachineCheckException) + +/* Data access exception. + * This is "never generated" by the MPC8xx. We jump to it for other + * translation errors. + */ + . = 0x300 +DataAccess: + EXCEPTION_PROLOG + mfspr r10,SPRN_DSISR + stw r10,_DSISR(r11) + mr r5,r10 + mfspr r4,SPRN_DAR + EXC_XFER_EE_LITE(0x300, handle_page_fault) + +/* Instruction access exception. + * This is "never generated" by the MPC8xx. We jump to it for other + * translation errors. + */ + . = 0x400 +InstructionAccess: + EXCEPTION_PROLOG + mr r4,r12 + mr r5,r9 + EXC_XFER_EE_LITE(0x400, handle_page_fault) + +/* External interrupt */ + EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) + +/* Alignment exception */ + . = 0x600 +Alignment: + EXCEPTION_PROLOG + mfspr r4,SPRN_DAR + stw r4,_DAR(r11) + mfspr r5,SPRN_DSISR + stw r5,_DSISR(r11) + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_EE(0x600, AlignmentException) + +/* Program check exception */ + EXCEPTION(0x700, ProgramCheck, ProgramCheckException, EXC_XFER_STD) + +/* No FPU on MPC8xx. This exception is not supposed to happen. +*/ + EXCEPTION(0x800, FPUnavailable, UnknownException, EXC_XFER_STD) + +/* Decrementer */ + EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE) + + EXCEPTION(0xa00, Trap_0a, UnknownException, EXC_XFER_EE) + EXCEPTION(0xb00, Trap_0b, UnknownException, EXC_XFER_EE) + +/* System call */ + . = 0xc00 +SystemCall: + EXCEPTION_PROLOG + EXC_XFER_EE_LITE(0xc00, DoSyscall) + +/* Single step - not used on 601 */ + EXCEPTION(0xd00, SingleStep, SingleStepException, EXC_XFER_STD) + EXCEPTION(0xe00, Trap_0e, UnknownException, EXC_XFER_EE) + EXCEPTION(0xf00, Trap_0f, UnknownException, EXC_XFER_EE) + +/* On the MPC8xx, this is a software emulation interrupt. It occurs + * for all unimplemented and illegal instructions. + */ + EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD) + + . = 0x1100 +/* + * For the MPC8xx, this is a software tablewalk to load the instruction + * TLB. It is modelled after the example in the Motorola manual. The task + * switch loads the M_TWB register with the pointer to the first level table. + * If we discover there is no second level table (value is zero) or if there + * is an invalid pte, we load that into the TLB, which causes another fault + * into the TLB Error interrupt where we can handle such problems. + * We have to use the MD_xxx registers for the tablewalk because the + * equivalent MI_xxx registers only perform the attribute functions. + */ +InstructionTLBMiss: +#ifdef CONFIG_8xx_CPU6 + stw r3, 8(r0) +#endif + DO_8xx_CPU6(0x3f80, r3) + mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ + mfcr r10 + stw r10, 0(r0) + stw r11, 4(r0) + mfspr r10, SPRN_SRR0 /* Get effective address of fault */ + DO_8xx_CPU6(0x3780, r3) + mtspr SPRN_MD_EPN, r10 /* Have to use MD_EPN for walk, MI_EPN can't */ + mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andi. r11, r10, 0x0800 /* Address >= 0x80000000 */ + beq 3f + lis r11, swapper_pg_dir@h + ori r11, r11, swapper_pg_dir@l + rlwimi r10, r11, 0, 2, 19 +3: + lwz r11, 0(r10) /* Get the level 1 entry */ + rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ + beq 2f /* If zero, don't try to find a pte */ + + /* We have a pte table, so load the MI_TWC with the attributes + * for this "segment." + */ + ori r11,r11,1 /* Set valid bit */ + DO_8xx_CPU6(0x2b80, r3) + mtspr SPRN_MI_TWC, r11 /* Set segment attributes */ + DO_8xx_CPU6(0x3b80, r3) + mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ + mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ + lwz r10, 0(r11) /* Get the pte */ + + ori r10, r10, _PAGE_ACCESSED + stw r10, 0(r11) + + /* The Linux PTE won't go exactly into the MMU TLB. + * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 24, 25, 26, and 27 must be + * set. All other Linux PTE bits control the behavior + * of the MMU. + */ +2: li r11, 0x00f0 + rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ + DO_8xx_CPU6(0x2d80, r3) + mtspr SPRN_MI_RPN, r10 /* Update TLB entry */ + + mfspr r10, SPRN_M_TW /* Restore registers */ + lwz r11, 0(r0) + mtcr r11 + lwz r11, 4(r0) +#ifdef CONFIG_8xx_CPU6 + lwz r3, 8(r0) +#endif + rfi + + . = 0x1200 +DataStoreTLBMiss: +#ifdef CONFIG_8xx_CPU6 + stw r3, 8(r0) +#endif + DO_8xx_CPU6(0x3f80, r3) + mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ + mfcr r10 + stw r10, 0(r0) + stw r11, 4(r0) + mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andi. r11, r10, 0x0800 + beq 3f + lis r11, swapper_pg_dir@h + ori r11, r11, swapper_pg_dir@l + rlwimi r10, r11, 0, 2, 19 +3: + lwz r11, 0(r10) /* Get the level 1 entry */ + rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ + beq 2f /* If zero, don't try to find a pte */ + + /* We have a pte table, so load fetch the pte from the table. + */ + ori r11, r11, 1 /* Set valid bit in physical L2 page */ + DO_8xx_CPU6(0x3b80, r3) + mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ + mfspr r10, SPRN_MD_TWC /* ....and get the pte address */ + lwz r10, 0(r10) /* Get the pte */ + + /* Insert the Guarded flag into the TWC from the Linux PTE. + * It is bit 27 of both the Linux PTE and the TWC (at least + * I got that right :-). It will be better when we can put + * this into the Linux pgd/pmd and load it in the operation + * above. + */ + rlwimi r11, r10, 0, 27, 27 + DO_8xx_CPU6(0x3b80, r3) + mtspr SPRN_MD_TWC, r11 + + mfspr r11, SPRN_MD_TWC /* get the pte address again */ + ori r10, r10, _PAGE_ACCESSED + stw r10, 0(r11) + + /* The Linux PTE won't go exactly into the MMU TLB. + * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 24, 25, 26, and 27 must be + * set. All other Linux PTE bits control the behavior + * of the MMU. + */ +2: li r11, 0x00f0 + rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ + DO_8xx_CPU6(0x3d80, r3) + mtspr SPRN_MD_RPN, r10 /* Update TLB entry */ + + mfspr r10, SPRN_M_TW /* Restore registers */ + lwz r11, 0(r0) + mtcr r11 + lwz r11, 4(r0) +#ifdef CONFIG_8xx_CPU6 + lwz r3, 8(r0) +#endif + rfi + +/* This is an instruction TLB error on the MPC8xx. This could be due + * to many reasons, such as executing guarded memory or illegal instruction + * addresses. There is nothing to do but handle a big time error fault. + */ + . = 0x1300 +InstructionTLBError: + b InstructionAccess + +/* This is the data TLB error on the MPC8xx. This could be due to + * many reasons, including a dirty update to a pte. We can catch that + * one here, but anything else is an error. First, we track down the + * Linux pte. If it is valid, write access is allowed, but the + * page dirty bit is not set, we will set it and reload the TLB. For + * any other case, we bail out to a higher level function that can + * handle it. + */ + . = 0x1400 +DataTLBError: +#ifdef CONFIG_8xx_CPU6 + stw r3, 8(r0) +#endif + DO_8xx_CPU6(0x3f80, r3) + mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ + mfcr r10 + stw r10, 0(r0) + stw r11, 4(r0) + + /* First, make sure this was a store operation. + */ + mfspr r10, SPRN_DSISR + andis. r11, r10, 0x0200 /* If set, indicates store op */ + beq 2f + + /* The EA of a data TLB miss is automatically stored in the MD_EPN + * register. The EA of a data TLB error is automatically stored in + * the DAR, but not the MD_EPN register. We must copy the 20 most + * significant bits of the EA from the DAR to MD_EPN before we + * start walking the page tables. We also need to copy the CASID + * value from the M_CASID register. + * Addendum: The EA of a data TLB error is _supposed_ to be stored + * in DAR, but it seems that this doesn't happen in some cases, such + * as when the error is due to a dcbi instruction to a page with a + * TLB that doesn't have the changed bit set. In such cases, there + * does not appear to be any way to recover the EA of the error + * since it is neither in DAR nor MD_EPN. As a workaround, the + * _PAGE_HWWRITE bit is set for all kernel data pages when the PTEs + * are initialized in mapin_ram(). This will avoid the problem, + * assuming we only use the dcbi instruction on kernel addresses. + */ + mfspr r10, SPRN_DAR + rlwinm r11, r10, 0, 0, 19 + ori r11, r11, MD_EVALID + mfspr r10, SPRN_M_CASID + rlwimi r11, r10, 0, 28, 31 + DO_8xx_CPU6(0x3780, r3) + mtspr SPRN_MD_EPN, r11 + + mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andi. r11, r10, 0x0800 + beq 3f + lis r11, swapper_pg_dir@h + ori r11, r11, swapper_pg_dir@l + rlwimi r10, r11, 0, 2, 19 +3: + lwz r11, 0(r10) /* Get the level 1 entry */ + rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ + beq 2f /* If zero, bail */ + + /* We have a pte table, so fetch the pte from the table. + */ + ori r11, r11, 1 /* Set valid bit in physical L2 page */ + DO_8xx_CPU6(0x3b80, r3) + mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ + mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ + lwz r10, 0(r11) /* Get the pte */ + + andi. r11, r10, _PAGE_RW /* Is it writeable? */ + beq 2f /* Bail out if not */ + + /* Update 'changed', among others. + */ + ori r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE + mfspr r11, SPRN_MD_TWC /* Get pte address again */ + stw r10, 0(r11) /* and update pte in table */ + + /* The Linux PTE won't go exactly into the MMU TLB. + * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 24, 25, 26, and 27 must be + * set. All other Linux PTE bits control the behavior + * of the MMU. + */ + li r11, 0x00f0 + rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ + DO_8xx_CPU6(0x3d80, r3) + mtspr SPRN_MD_RPN, r10 /* Update TLB entry */ + + mfspr r10, SPRN_M_TW /* Restore registers */ + lwz r11, 0(r0) + mtcr r11 + lwz r11, 4(r0) +#ifdef CONFIG_8xx_CPU6 + lwz r3, 8(r0) +#endif + rfi +2: + mfspr r10, SPRN_M_TW /* Restore registers */ + lwz r11, 0(r0) + mtcr r11 + lwz r11, 4(r0) +#ifdef CONFIG_8xx_CPU6 + lwz r3, 8(r0) +#endif + b DataAccess + + EXCEPTION(0x1500, Trap_15, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1600, Trap_16, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1700, Trap_17, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1800, Trap_18, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1900, Trap_19, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1a00, Trap_1a, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1b00, Trap_1b, UnknownException, EXC_XFER_EE) + +/* On the MPC8xx, these next four traps are used for development + * support of breakpoints and such. Someday I will get around to + * using them. + */ + EXCEPTION(0x1c00, Trap_1c, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1d00, Trap_1d, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1e00, Trap_1e, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1f00, Trap_1f, UnknownException, EXC_XFER_EE) + + . = 0x2000 + + .globl giveup_fpu +giveup_fpu: + blr + +/* + * This is where the main kernel code starts. + */ +start_here: + /* ptr to current */ + lis r2,init_task@h + ori r2,r2,init_task@l + + /* ptr to phys current thread */ + tophys(r4,r2) + addi r4,r4,THREAD /* init task's THREAD */ + mtspr SPRN_SPRG3,r4 + li r3,0 + mtspr SPRN_SPRG2,r3 /* 0 => r1 has kernel sp */ + + /* stack */ + lis r1,init_thread_union@ha + addi r1,r1,init_thread_union@l + li r0,0 + stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1) + + bl early_init /* We have to do this with MMU on */ + +/* + * Decide what sort of machine this is and initialize the MMU. + */ + mr r3,r31 + mr r4,r30 + mr r5,r29 + mr r6,r28 + mr r7,r27 + bl machine_init + bl MMU_init + +/* + * Go back to running unmapped so we can load up new values + * and change to using our exception vectors. + * On the 8xx, all we have to do is invalidate the TLB to clear + * the old 8M byte TLB mappings and load the page table base register. + */ + /* The right way to do this would be to track it down through + * init's THREAD like the context switch code does, but this is + * easier......until someone changes init's static structures. + */ + lis r6, swapper_pg_dir@h + ori r6, r6, swapper_pg_dir@l + tophys(r6,r6) +#ifdef CONFIG_8xx_CPU6 + lis r4, cpu6_errata_word@h + ori r4, r4, cpu6_errata_word@l + li r3, 0x3980 + stw r3, 12(r4) + lwz r3, 12(r4) +#endif + mtspr SPRN_M_TWB, r6 + lis r4,2f@h + ori r4,r4,2f@l + tophys(r4,r4) + li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR) + mtspr SPRN_SRR0,r4 + mtspr SPRN_SRR1,r3 + rfi +/* Load up the kernel context */ +2: + SYNC /* Force all PTE updates to finish */ + tlbia /* Clear all TLB entries */ + sync /* wait for tlbia/tlbie to finish */ + TLBSYNC /* ... on all CPUs */ + + /* set up the PTE pointers for the Abatron bdiGDB. + */ + tovirt(r6,r6) + lis r5, abatron_pteptrs@h + ori r5, r5, abatron_pteptrs@l + stw r5, 0xf0(r0) /* Must match your Abatron config file */ + tophys(r5,r5) + stw r6, 0(r5) + +/* Now turn on the MMU for real! */ + li r4,MSR_KERNEL + lis r3,start_kernel@h + ori r3,r3,start_kernel@l + mtspr SPRN_SRR0,r3 + mtspr SPRN_SRR1,r4 + rfi /* enable MMU and jump to start_kernel */ + +/* Set up the initial MMU state so we can do the first level of + * kernel initialization. This maps the first 8 MBytes of memory 1:1 + * virtual to physical. Also, set the cache mode since that is defined + * by TLB entries and perform any additional mapping (like of the IMMR). + * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel, + * 24 Mbytes of data, and the 8M IMMR space. Anything not covered by + * these mappings is mapped by page tables. + */ +initial_mmu: + tlbia /* Invalidate all TLB entries */ +#ifdef CONFIG_PIN_TLB + lis r8, MI_RSV4I@h + ori r8, r8, 0x1c00 +#else + li r8, 0 +#endif + mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */ + +#ifdef CONFIG_PIN_TLB + lis r10, (MD_RSV4I | MD_RESETVAL)@h + ori r10, r10, 0x1c00 + mr r8, r10 +#else + lis r10, MD_RESETVAL@h +#endif +#ifndef CONFIG_8xx_COPYBACK + oris r10, r10, MD_WTDEF@h +#endif + mtspr SPRN_MD_CTR, r10 /* Set data TLB control */ + + /* Now map the lower 8 Meg into the TLBs. For this quick hack, + * we can load the instruction and data TLB registers with the + * same values. + */ + lis r8, KERNELBASE@h /* Create vaddr for TLB */ + ori r8, r8, MI_EVALID /* Mark it valid */ + mtspr SPRN_MI_EPN, r8 + mtspr SPRN_MD_EPN, r8 + li r8, MI_PS8MEG /* Set 8M byte page */ + ori r8, r8, MI_SVALID /* Make it valid */ + mtspr SPRN_MI_TWC, r8 + mtspr SPRN_MD_TWC, r8 + li r8, MI_BOOTINIT /* Create RPN for address 0 */ + mtspr SPRN_MI_RPN, r8 /* Store TLB entry */ + mtspr SPRN_MD_RPN, r8 + lis r8, MI_Kp@h /* Set the protection mode */ + mtspr SPRN_MI_AP, r8 + mtspr SPRN_MD_AP, r8 + + /* Map another 8 MByte at the IMMR to get the processor + * internal registers (among other things). + */ +#ifdef CONFIG_PIN_TLB + addi r10, r10, 0x0100 + mtspr SPRN_MD_CTR, r10 +#endif + mfspr r9, 638 /* Get current IMMR */ + andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */ + + mr r8, r9 /* Create vaddr for TLB */ + ori r8, r8, MD_EVALID /* Mark it valid */ + mtspr SPRN_MD_EPN, r8 + li r8, MD_PS8MEG /* Set 8M byte page */ + ori r8, r8, MD_SVALID /* Make it valid */ + mtspr SPRN_MD_TWC, r8 + mr r8, r9 /* Create paddr for TLB */ + ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */ + mtspr SPRN_MD_RPN, r8 + +#ifdef CONFIG_PIN_TLB + /* Map two more 8M kernel data pages. + */ + addi r10, r10, 0x0100 + mtspr SPRN_MD_CTR, r10 + + lis r8, KERNELBASE@h /* Create vaddr for TLB */ + addis r8, r8, 0x0080 /* Add 8M */ + ori r8, r8, MI_EVALID /* Mark it valid */ + mtspr SPRN_MD_EPN, r8 + li r9, MI_PS8MEG /* Set 8M byte page */ + ori r9, r9, MI_SVALID /* Make it valid */ + mtspr SPRN_MD_TWC, r9 + li r11, MI_BOOTINIT /* Create RPN for address 0 */ + addis r11, r11, 0x0080 /* Add 8M */ + mtspr SPRN_MD_RPN, r8 + + addis r8, r8, 0x0080 /* Add 8M */ + mtspr SPRN_MD_EPN, r8 + mtspr SPRN_MD_TWC, r9 + addis r11, r11, 0x0080 /* Add 8M */ + mtspr SPRN_MD_RPN, r8 +#endif + + /* Since the cache is enabled according to the information we + * just loaded into the TLB, invalidate and enable the caches here. + * We should probably check/set other modes....later. + */ + lis r8, IDC_INVALL@h + mtspr SPRN_IC_CST, r8 + mtspr SPRN_DC_CST, r8 + lis r8, IDC_ENABLE@h + mtspr SPRN_IC_CST, r8 +#ifdef CONFIG_8xx_COPYBACK + mtspr SPRN_DC_CST, r8 +#else + /* For a debug option, I left this here to easily enable + * the write through cache mode + */ + lis r8, DC_SFWT@h + mtspr SPRN_DC_CST, r8 + lis r8, IDC_ENABLE@h + mtspr SPRN_DC_CST, r8 +#endif + blr + + +/* + * Set up to use a given MMU context. + * r3 is context number, r4 is PGD pointer. + * + * We place the physical address of the new task page directory loaded + * into the MMU base register, and set the ASID compare register with + * the new "context." + */ +_GLOBAL(set_context) + +#ifdef CONFIG_BDI_SWITCH + /* Context switch the PTE pointer for the Abatron BDI2000. + * The PGDIR is passed as second argument. + */ + lis r5, KERNELBASE@h + lwz r5, 0xf0(r5) + stw r4, 0x4(r5) +#endif + +#ifdef CONFIG_8xx_CPU6 + lis r6, cpu6_errata_word@h + ori r6, r6, cpu6_errata_word@l + tophys (r4, r4) + li r7, 0x3980 + stw r7, 12(r6) + lwz r7, 12(r6) + mtspr SPRN_M_TWB, r4 /* Update MMU base address */ + li r7, 0x3380 + stw r7, 12(r6) + lwz r7, 12(r6) + mtspr SPRN_M_CASID, r3 /* Update context */ +#else + mtspr SPRN_M_CASID,r3 /* Update context */ + tophys (r4, r4) + mtspr SPRN_M_TWB, r4 /* and pgd */ +#endif + SYNC + blr + +#ifdef CONFIG_8xx_CPU6 +/* It's here because it is unique to the 8xx. + * It is important we get called with interrupts disabled. I used to + * do that, but it appears that all code that calls this already had + * interrupt disabled. + */ + .globl set_dec_cpu6 +set_dec_cpu6: + lis r7, cpu6_errata_word@h + ori r7, r7, cpu6_errata_word@l + li r4, 0x2c00 + stw r4, 8(r7) + lwz r4, 8(r7) + mtspr 22, r3 /* Update Decrementer */ + SYNC + blr +#endif + +/* + * We put a few things here that have to be page-aligned. + * This stuff goes at the beginning of the data segment, + * which is page-aligned. + */ + .data + .globl sdata +sdata: + .globl empty_zero_page +empty_zero_page: + .space 4096 + + .globl swapper_pg_dir +swapper_pg_dir: + .space 4096 + +/* + * This space gets a copy of optional info passed to us by the bootstrap + * Used to pass parameters into the kernel like root=/dev/sda1, etc. + */ + .globl cmd_line +cmd_line: + .space 512 + +/* Room for two PTE table poiners, usually the kernel and current user + * pointer to their respective root page table (pgdir). + */ +abatron_pteptrs: + .space 8 + +#ifdef CONFIG_8xx_CPU6 + .globl cpu6_errata_word +cpu6_errata_word: + .space 16 +#endif + |