arch/cris/kernel/setup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *
   4  *  linux/arch/cris/kernel/setup.c
   5  *
   6  *  Copyright (C) 1995  Linus Torvalds
   7  *  Copyright (c) 2001  Axis Communications AB
   8  */
   9
  10 /*
  11  * This file handles the architecture-dependent parts of initialization
  12  */
  13
  14 #include <linux/init.h>
  15 #include <linux/mm.h>
  16 #include <linux/bootmem.h>
  17 #include <asm/pgtable.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/screen_info.h>
  20 #include <linux/utsname.h>
  21 #include <linux/pfn.h>
  22 #include <linux/cpu.h>
  23 #include <linux/of.h>
  24 #include <linux/of_fdt.h>
  25 #include <asm/setup.h>
  26 #include <arch/system.h>
  27 #include <asm/sections.h>
  28
  29 /*
  30  * Setup options
  31  */
  32 struct screen_info screen_info;
  33
  34 extern int root_mountflags;
  35
  36 char __initdata cris_command_line[COMMAND_LINE_SIZE] = { 0, };
  37
  38 extern const unsigned long text_start, edata; /* set by the linker script */
  39 extern unsigned long dram_start, dram_end;
  40
  41 extern unsigned long romfs_start, romfs_length, romfs_in_flash; /* from head.S */
  42
  43 static struct cpu cpu_devices[NR_CPUS];
  44
  45 extern void show_etrax_copyright(void);         /* arch-vX/kernel/setup.c */
  46
  47 /* This mainly sets up the memory area, and can be really confusing.
  48  *
  49  * The physical DRAM is virtually mapped into dram_start to dram_end
  50  * (usually c0000000 to c0000000 + DRAM size). The physical address is
  51  * given by the macro __pa().
  52  *
  53  * In this DRAM, the kernel code and data is loaded, in the beginning.
  54  * It really starts at c0004000 to make room for some special pages -
  55  * the start address is text_start. The kernel data ends at _end. After
  56  * this the ROM filesystem is appended (if there is any).
  57  *
  58  * Between this address and dram_end, we have RAM pages usable to the
  59  * boot code and the system.
  60  *
  61  */
  62
  63 void __init setup_arch(char **cmdline_p)
  64 {
  65         extern void init_etrax_debug(void);
  66         unsigned long bootmap_size;
  67         unsigned long start_pfn, max_pfn;
  68         unsigned long memory_start;
  69
  70 #ifdef CONFIG_OF
  71         early_init_dt_scan(__dtb_start);
  72 #endif
  73
  74         /* register an initial console printing routine for printk's */
  75
  76         init_etrax_debug();
  77
  78         /* we should really poll for DRAM size! */
  79
  80         high_memory = &dram_end;
  81
  82         if(romfs_in_flash || !romfs_length) {
  83                 /* if we have the romfs in flash, or if there is no rom filesystem,
  84                  * our free area starts directly after the BSS
  85                  */
  86                 memory_start = (unsigned long) &_end;
  87         } else {
  88                 /* otherwise the free area starts after the ROM filesystem */
  89                 printk("ROM fs in RAM, size %lu bytes\n", romfs_length);
  90                 memory_start = romfs_start + romfs_length;
  91         }
  92
  93         /* process 1's initial memory region is the kernel code/data */
  94
  95         init_mm.start_code = (unsigned long) &text_start;
  96         init_mm.end_code =   (unsigned long) &_etext;
  97         init_mm.end_data =   (unsigned long) &_edata;
  98         init_mm.brk =        (unsigned long) &_end;
  99
 100         /* min_low_pfn points to the start of DRAM, start_pfn points
 101          * to the first DRAM pages after the kernel, and max_low_pfn
 102          * to the end of DRAM.
 103          */
 104
 105         /*
 106          * partially used pages are not usable - thus
 107          * we are rounding upwards:
 108          */
 109
 110         start_pfn = PFN_UP(memory_start);  /* usually c0000000 + kernel + romfs */
 111         max_pfn =   PFN_DOWN((unsigned long)high_memory); /* usually c0000000 + dram size */
 112
 113         /*
 114          * Initialize the boot-time allocator (start, end)
 115          *
 116          * We give it access to all our DRAM, but we could as well just have
 117          * given it a small slice. No point in doing that though, unless we
 118          * have non-contiguous memory and want the boot-stuff to be in, say,
 119          * the smallest area.
 120          *
 121          * It will put a bitmap of the allocated pages in the beginning
 122          * of the range we give it, but it won't mark the bitmaps pages
 123          * as reserved. We have to do that ourselves below.
 124          *
 125          * We need to use init_bootmem_node instead of init_bootmem
 126          * because our map starts at a quite high address (min_low_pfn).
 127          */
 128
 129         max_low_pfn = max_pfn;
 130         min_low_pfn = PAGE_OFFSET >> PAGE_SHIFT;
 131
 132         bootmap_size = init_bootmem_node(NODE_DATA(0), start_pfn,
 133                                          min_low_pfn,
 134                                          max_low_pfn);
 135
 136         /* And free all memory not belonging to the kernel (addr, size) */
 137
 138         free_bootmem(PFN_PHYS(start_pfn), PFN_PHYS(max_pfn - start_pfn));
 139
 140         /*
 141          * Reserve the bootmem bitmap itself as well. We do this in two
 142          * steps (first step was init_bootmem()) because this catches
 143          * the (very unlikely) case of us accidentally initializing the
 144          * bootmem allocator with an invalid RAM area.
 145          *
 146          * Arguments are start, size
 147          */
 148
 149         reserve_bootmem(PFN_PHYS(start_pfn), bootmap_size, BOOTMEM_DEFAULT);
 150
 151         unflatten_and_copy_device_tree();
 152
 153         /* paging_init() sets up the MMU and marks all pages as reserved */
 154
 155         paging_init();
 156
 157         *cmdline_p = cris_command_line;
 158
 159 #ifdef CONFIG_ETRAX_CMDLINE
 160         if (!strcmp(cris_command_line, "")) {
 161                 strlcpy(cris_command_line, CONFIG_ETRAX_CMDLINE, COMMAND_LINE_SIZE);
 162                 cris_command_line[COMMAND_LINE_SIZE - 1] = '\0';
 163         }
 164 #endif
 165
 166         /* Save command line for future references. */
 167         memcpy(boot_command_line, cris_command_line, COMMAND_LINE_SIZE);
 168         boot_command_line[COMMAND_LINE_SIZE - 1] = '\0';
 169
 170         /* give credit for the CRIS port */
 171         show_etrax_copyright();
 172
 173         /* Setup utsname */
 174         strcpy(init_utsname()->machine, cris_machine_name);
 175 }
 176
 177 #ifdef CONFIG_PROC_FS
 178 static void *c_start(struct seq_file *m, loff_t *pos)
 179 {
 180         return *pos < nr_cpu_ids ? (void *)(int)(*pos + 1) : NULL;
 181 }
 182
 183 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
 184 {
 185         ++*pos;
 186         return c_start(m, pos);
 187 }
 188
 189 static void c_stop(struct seq_file *m, void *v)
 190 {
 191 }
 192
 193 extern int show_cpuinfo(struct seq_file *m, void *v);
 194
 195 const struct seq_operations cpuinfo_op = {
 196         .start = c_start,
 197         .next  = c_next,
 198         .stop  = c_stop,
 199         .show  = show_cpuinfo,
 200 };
 201 #endif /* CONFIG_PROC_FS */
 202
 203 static int __init topology_init(void)
 204 {
 205         int i;
 206
 207         for_each_possible_cpu(i) {
 208                  return register_cpu(&cpu_devices[i], i);
 209         }
 210
 211         return 0;
 212 }
 213
 214 subsys_initcall(topology_init);