linux/arch/nios2/kernel/setup.c
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   1/*
   2 * Nios2-specific parts of system setup
   3 *
   4 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
   5 * Copyright (C) 2004 Microtronix Datacom Ltd.
   6 * Copyright (C) 2001 Vic Phillips <vic@microtronix.com>
   7 *
   8 * This file is subject to the terms and conditions of the GNU General Public
   9 * License. See the file "COPYING" in the main directory of this archive
  10 * for more details.
  11 */
  12
  13#include <linux/export.h>
  14#include <linux/kernel.h>
  15#include <linux/mm.h>
  16#include <linux/sched.h>
  17#include <linux/sched/task.h>
  18#include <linux/console.h>
  19#include <linux/memblock.h>
  20#include <linux/initrd.h>
  21#include <linux/of_fdt.h>
  22#include <linux/screen_info.h>
  23
  24#include <asm/mmu_context.h>
  25#include <asm/sections.h>
  26#include <asm/setup.h>
  27#include <asm/cpuinfo.h>
  28
  29unsigned long memory_start;
  30EXPORT_SYMBOL(memory_start);
  31
  32unsigned long memory_end;
  33EXPORT_SYMBOL(memory_end);
  34
  35static struct pt_regs fake_regs = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  36                                        0, 0, 0, 0, 0, 0,
  37                                        0};
  38
  39#ifdef CONFIG_VT
  40struct screen_info screen_info;
  41#endif
  42
  43/* Copy a short hook instruction sequence to the exception address */
  44static inline void copy_exception_handler(unsigned int addr)
  45{
  46        unsigned int start = (unsigned int) exception_handler_hook;
  47        volatile unsigned int tmp = 0;
  48
  49        if (start == addr) {
  50                /* The CPU exception address already points to the handler. */
  51                return;
  52        }
  53
  54        __asm__ __volatile__ (
  55                "ldw    %2,0(%0)\n"
  56                "stw    %2,0(%1)\n"
  57                "ldw    %2,4(%0)\n"
  58                "stw    %2,4(%1)\n"
  59                "ldw    %2,8(%0)\n"
  60                "stw    %2,8(%1)\n"
  61                "flushd 0(%1)\n"
  62                "flushd 4(%1)\n"
  63                "flushd 8(%1)\n"
  64                "flushi %1\n"
  65                "addi   %1,%1,4\n"
  66                "flushi %1\n"
  67                "addi   %1,%1,4\n"
  68                "flushi %1\n"
  69                "flushp\n"
  70                : /* no output registers */
  71                : "r" (start), "r" (addr), "r" (tmp)
  72                : "memory"
  73        );
  74}
  75
  76/* Copy the fast TLB miss handler */
  77static inline void copy_fast_tlb_miss_handler(unsigned int addr)
  78{
  79        unsigned int start = (unsigned int) fast_handler;
  80        unsigned int end = (unsigned int) fast_handler_end;
  81        volatile unsigned int tmp = 0;
  82
  83        __asm__ __volatile__ (
  84                "1:\n"
  85                "       ldw     %3,0(%0)\n"
  86                "       stw     %3,0(%1)\n"
  87                "       flushd  0(%1)\n"
  88                "       flushi  %1\n"
  89                "       flushp\n"
  90                "       addi    %0,%0,4\n"
  91                "       addi    %1,%1,4\n"
  92                "       bne     %0,%2,1b\n"
  93                : /* no output registers */
  94                : "r" (start), "r" (addr), "r" (end), "r" (tmp)
  95                : "memory"
  96        );
  97}
  98
  99/*
 100 * save args passed from u-boot, called from head.S
 101 *
 102 * @r4: NIOS magic
 103 * @r5: initrd start
 104 * @r6: initrd end or fdt
 105 * @r7: kernel command line
 106 */
 107asmlinkage void __init nios2_boot_init(unsigned r4, unsigned r5, unsigned r6,
 108                                       unsigned r7)
 109{
 110        unsigned dtb_passed = 0;
 111        char cmdline_passed[COMMAND_LINE_SIZE] __maybe_unused = { 0, };
 112
 113#if defined(CONFIG_NIOS2_PASS_CMDLINE)
 114        if (r4 == 0x534f494e) { /* r4 is magic NIOS */
 115#if defined(CONFIG_BLK_DEV_INITRD)
 116                if (r5) { /* initramfs */
 117                        initrd_start = r5;
 118                        initrd_end = r6;
 119                }
 120#endif /* CONFIG_BLK_DEV_INITRD */
 121                dtb_passed = r6;
 122
 123                if (r7)
 124                        strlcpy(cmdline_passed, (char *)r7, COMMAND_LINE_SIZE);
 125        }
 126#endif
 127
 128        early_init_devtree((void *)dtb_passed);
 129
 130#ifndef CONFIG_CMDLINE_FORCE
 131        if (cmdline_passed[0])
 132                strlcpy(boot_command_line, cmdline_passed, COMMAND_LINE_SIZE);
 133#ifdef CONFIG_NIOS2_CMDLINE_IGNORE_DTB
 134        else
 135                strlcpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 136#endif
 137#endif
 138
 139        parse_early_param();
 140}
 141
 142static void __init find_limits(unsigned long *min, unsigned long *max_low,
 143                               unsigned long *max_high)
 144{
 145        *max_low = PFN_DOWN(memblock_get_current_limit());
 146        *min = PFN_UP(memblock_start_of_DRAM());
 147        *max_high = PFN_DOWN(memblock_end_of_DRAM());
 148}
 149
 150void __init setup_arch(char **cmdline_p)
 151{
 152        int dram_start;
 153
 154        console_verbose();
 155
 156        memory_start = memblock_start_of_DRAM();
 157        memory_end = memblock_end_of_DRAM();
 158
 159        init_mm.start_code = (unsigned long) _stext;
 160        init_mm.end_code = (unsigned long) _etext;
 161        init_mm.end_data = (unsigned long) _edata;
 162        init_mm.brk = (unsigned long) _end;
 163        init_task.thread.kregs = &fake_regs;
 164
 165        /* Keep a copy of command line */
 166        *cmdline_p = boot_command_line;
 167
 168        find_limits(&min_low_pfn, &max_low_pfn, &max_pfn);
 169        max_mapnr = max_low_pfn;
 170
 171        memblock_reserve(__pa_symbol(_stext), _end - _stext);
 172#ifdef CONFIG_BLK_DEV_INITRD
 173        if (initrd_start) {
 174                memblock_reserve(virt_to_phys((void *)initrd_start),
 175                                initrd_end - initrd_start);
 176        }
 177#endif /* CONFIG_BLK_DEV_INITRD */
 178
 179        early_init_fdt_reserve_self();
 180        early_init_fdt_scan_reserved_mem();
 181
 182        unflatten_and_copy_device_tree();
 183
 184        setup_cpuinfo();
 185
 186        copy_exception_handler(cpuinfo.exception_addr);
 187
 188        mmu_init();
 189
 190        copy_fast_tlb_miss_handler(cpuinfo.fast_tlb_miss_exc_addr);
 191
 192        /*
 193         * Initialize MMU context handling here because data from cpuinfo is
 194         * needed for this.
 195         */
 196        mmu_context_init();
 197
 198        /*
 199         * get kmalloc into gear
 200         */
 201        paging_init();
 202}
 203