arch/nios2/kernel/setup.c

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