setup.c

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/*
 *
 *  linux/arch/cris/kernel/setup.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Copyright (c) 2001  Axis Communications AB
 */

/*
 * This file handles the architecture-dependent parts of initialization
 */

#include <linux/init.h>
#include <linux/mm.h>
#include <linux/bootmem.h>
#include <asm/pgtable.h>
#include <linux/seq_file.h>
#include <linux/screen_info.h>
#include <linux/utsname.h>
#include <linux/pfn.h>
#include <linux/cpu.h>
#include <asm/setup.h>
#include <arch/system.h>

/*
 * Setup options
 */
struct screen_info screen_info;

extern int root_mountflags;
extern char _etext, _edata, _end;

char __initdata cris_command_line[COMMAND_LINE_SIZE] = { 0, };

extern const unsigned long text_start, edata; /* set by the linker script */
extern unsigned long dram_start, dram_end;

extern unsigned long romfs_start, romfs_length, romfs_in_flash; /* from head.S */

static struct cpu cpu_devices[NR_CPUS];

extern void show_etrax_copyright(void);     /* arch-vX/kernel/setup.c */

/* This mainly sets up the memory area, and can be really confusing.
 *
 * The physical DRAM is virtually mapped into dram_start to dram_end
 * (usually c0000000 to c0000000 + DRAM size). The physical address is
 * given by the macro __pa().
 *
 * In this DRAM, the kernel code and data is loaded, in the beginning.
 * It really starts at c0004000 to make room for some special pages -
 * the start address is text_start. The kernel data ends at _end. After
 * this the ROM filesystem is appended (if there is any).
 *
 * Between this address and dram_end, we have RAM pages usable to the
 * boot code and the system.
 *
 */

void __init setup_arch(char **cmdline_p)
{
    extern void init_etrax_debug(void);
    unsigned long bootmap_size;
    unsigned long start_pfn, max_pfn;
    unsigned long memory_start;

    /* register an initial console printing routine for printk's */

    init_etrax_debug();

    /* we should really poll for DRAM size! */

    high_memory = &dram_end;

    if(romfs_in_flash || !romfs_length) {
        /* if we have the romfs in flash, or if there is no rom filesystem,
         * our free area starts directly after the BSS
         */
        memory_start = (unsigned long) &_end;
    } else {
        /* otherwise the free area starts after the ROM filesystem */
        printk("ROM fs in RAM, size %lu bytes\n", romfs_length);
        memory_start = romfs_start + romfs_length;
    }

    /* process 1's initial memory region is the kernel code/data */

    init_mm.start_code = (unsigned long) &text_start;
    init_mm.end_code =   (unsigned long) &_etext;
    init_mm.end_data =   (unsigned long) &_edata;
    init_mm.brk =        (unsigned long) &_end;

    /* min_low_pfn points to the start of DRAM, start_pfn points
     * to the first DRAM pages after the kernel, and max_low_pfn
     * to the end of DRAM.
     */

        /*
         * partially used pages are not usable - thus
         * we are rounding upwards:
         */

        start_pfn = PFN_UP(memory_start);  /* usually c0000000 + kernel + romfs */
    max_pfn =   PFN_DOWN((unsigned long)high_memory); /* usually c0000000 + dram size */

        /*
         * Initialize the boot-time allocator (start, end)
     *
     * We give it access to all our DRAM, but we could as well just have
     * given it a small slice. No point in doing that though, unless we
     * have non-contiguous memory and want the boot-stuff to be in, say,
     * the smallest area.
     *
     * It will put a bitmap of the allocated pages in the beginning
     * of the range we give it, but it won't mark the bitmaps pages
     * as reserved. We have to do that ourselves below.
     *
     * We need to use init_bootmem_node instead of init_bootmem
     * because our map starts at a quite high address (min_low_pfn).
         */

    max_low_pfn = max_pfn;
    min_low_pfn = PAGE_OFFSET >> PAGE_SHIFT;

    bootmap_size = init_bootmem_node(NODE_DATA(0), start_pfn,
                     min_low_pfn,
                     max_low_pfn);

    /* And free all memory not belonging to the kernel (addr, size) */

    free_bootmem(PFN_PHYS(start_pfn), PFN_PHYS(max_pfn - start_pfn));

        /*
         * Reserve the bootmem bitmap itself as well. We do this in two
         * steps (first step was init_bootmem()) because this catches
         * the (very unlikely) case of us accidentally initializing the
         * bootmem allocator with an invalid RAM area.
     *
     * Arguments are start, size
         */

    reserve_bootmem(PFN_PHYS(start_pfn), bootmap_size, BOOTMEM_DEFAULT);

    /* paging_init() sets up the MMU and marks all pages as reserved */

    paging_init();

    *cmdline_p = cris_command_line;

#ifdef CONFIG_ETRAX_CMDLINE
        if (!strcmp(cris_command_line, "")) {
        strlcpy(cris_command_line, CONFIG_ETRAX_CMDLINE, COMMAND_LINE_SIZE);
        cris_command_line[COMMAND_LINE_SIZE - 1] = '\0';
    }
#endif

    /* Save command line for future references. */
    memcpy(boot_command_line, cris_command_line, COMMAND_LINE_SIZE);
    boot_command_line[COMMAND_LINE_SIZE - 1] = '\0';

    /* give credit for the CRIS port */
    show_etrax_copyright();

    /* Setup utsname */
    strcpy(init_utsname()->machine, cris_machine_name);
}

static void *c_start(struct seq_file *m, loff_t *pos)
{
    return *pos < nr_cpu_ids ? (void *)(int)(*pos + 1) : NULL;
}

static void *c_next(struct seq_file *m, void *v, loff_t *pos)
{
    ++*pos;
    return c_start(m, pos);
}

static void c_stop(struct seq_file *m, void *v)
{
}

extern int show_cpuinfo(struct seq_file *m, void *v);

const struct seq_operations cpuinfo_op = {
    .start = c_start,
    .next  = c_next,
    .stop  = c_stop,
    .show  = show_cpuinfo,
};

static int __init topology_init(void)
{
    int i;

    for_each_possible_cpu(i) {
         return register_cpu(&cpu_devices[i], i);
    }

    return 0;
}

subsys_initcall(topology_init);