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+/*
+ * 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 */
+
+#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
+
+.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:
+
+#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+r11 - r5 contain pointer to command line */
+ lbu r2, r5, r11
+ beqid r2, skip /* Skip if no data */
+ sb r2, r4, r11 /* addr[r4+r11]= 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 + r11 */
+ sw r7, r4, r11 /* addr[r4 + r11] = 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:
+
+ /* 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
+
+ /*
+ * 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