olpc_ofw.c

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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <asm/page.h>
#include <asm/setup.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/olpc_ofw.h>

/* address of OFW callback interface; will be NULL if OFW isn't found */
static int (*olpc_ofw_cif)(int *);

/* page dir entry containing OFW's pgdir table; filled in by head_32.S */
u32 olpc_ofw_pgd __initdata;

static DEFINE_SPINLOCK(ofw_lock);

#define MAXARGS 10

void __init setup_olpc_ofw_pgd(void)
{
    pgd_t *base, *ofw_pde;

    if (!olpc_ofw_cif)
        return;

    /* fetch OFW's PDE */
    base = early_ioremap(olpc_ofw_pgd, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
    if (!base) {
        printk(KERN_ERR "failed to remap OFW's pgd - disabling OFW!\n");
        olpc_ofw_cif = NULL;
        return;
    }
    ofw_pde = &base[OLPC_OFW_PDE_NR];

    /* install OFW's PDE permanently into the kernel's pgtable */
    set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
    /* implicit optimization barrier here due to uninline function return */

    early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
}

int __olpc_ofw(const char *name, int nr_args, const void **args, int nr_res,
        void **res)
{
    int ofw_args[MAXARGS + 3];
    unsigned long flags;
    int ret, i, *p;

    BUG_ON(nr_args + nr_res > MAXARGS);

    if (!olpc_ofw_cif)
        return -EIO;

    ofw_args[0] = (int)name;
    ofw_args[1] = nr_args;
    ofw_args[2] = nr_res;

    p = &ofw_args[3];
    for (i = 0; i < nr_args; i++, p++)
        *p = (int)args[i];

    /* call into ofw */
    spin_lock_irqsave(&ofw_lock, flags);
    ret = olpc_ofw_cif(ofw_args);
    spin_unlock_irqrestore(&ofw_lock, flags);

    if (!ret) {
        for (i = 0; i < nr_res; i++, p++)
            *((int *)res[i]) = *p;
    }

    return ret;
}
EXPORT_SYMBOL_GPL(__olpc_ofw);

bool olpc_ofw_present(void)
{
    return olpc_ofw_cif != NULL;
}
EXPORT_SYMBOL_GPL(olpc_ofw_present);

/* OFW cif _should_ be above this address */
#define OFW_MIN 0xff000000

/* OFW starts on a 1MB boundary */
#define OFW_BOUND (1<<20)

void __init olpc_ofw_detect(void)
{
    struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
    unsigned long start;

    /* ensure OFW booted us by checking for "OFW " string */
    if (hdr->ofw_magic != OLPC_OFW_SIG)
        return;

    olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;

    if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
        printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
                (unsigned long)olpc_ofw_cif);
        olpc_ofw_cif = NULL;
        return;
    }

    /* determine where OFW starts in memory */
    start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
    printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
            (unsigned long)olpc_ofw_cif, (-start) >> 20);
    reserve_top_address(-start);
}

bool __init olpc_ofw_is_installed(void)
{
    return olpc_ofw_cif != NULL;
}