centaur.c

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#include <linux/init.h>
#include <linux/mm.h>

#include <asm/mtrr.h>
#include <asm/msr.h>

#include "mtrr.h"

static struct {
    unsigned long high;
    unsigned long low;
} centaur_mcr[8];

static u8 centaur_mcr_reserved;
static u8 centaur_mcr_type; /* 0 for winchip, 1 for winchip2 */

static int
centaur_get_free_region(unsigned long base, unsigned long size, int replace_reg)
{
    unsigned long lbase, lsize;
    mtrr_type ltype;
    int i, max;

    max = num_var_ranges;
    if (replace_reg >= 0 && replace_reg < max)
        return replace_reg;

    for (i = 0; i < max; ++i) {
        if (centaur_mcr_reserved & (1 << i))
            continue;
        mtrr_if->get(i, &lbase, &lsize, &ltype);
        if (lsize == 0)
            return i;
    }

    return -ENOSPC;
}

/*
 * Report boot time MCR setups
 */
void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
{
    centaur_mcr[mcr].low = lo;
    centaur_mcr[mcr].high = hi;
}

static void
centaur_get_mcr(unsigned int reg, unsigned long *base,
        unsigned long *size, mtrr_type * type)
{
    *base = centaur_mcr[reg].high >> PAGE_SHIFT;
    *size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
    *type = MTRR_TYPE_WRCOMB;       /* write-combining  */

    if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
        *type = MTRR_TYPE_UNCACHABLE;
    if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
        *type = MTRR_TYPE_WRBACK;
    if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
        *type = MTRR_TYPE_WRBACK;
}

static void
centaur_set_mcr(unsigned int reg, unsigned long base,
        unsigned long size, mtrr_type type)
{
    unsigned long low, high;

    if (size == 0) {
        /* Disable */
        high = low = 0;
    } else {
        high = base << PAGE_SHIFT;
        if (centaur_mcr_type == 0) {
            /* Only support write-combining... */
            low = -size << PAGE_SHIFT | 0x1f;
        } else {
            if (type == MTRR_TYPE_UNCACHABLE)
                low = -size << PAGE_SHIFT | 0x02; /* NC */
            else
                low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
        }
    }
    centaur_mcr[reg].high = high;
    centaur_mcr[reg].low = low;
    wrmsr(MSR_IDT_MCR0 + reg, low, high);
}

static int
centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
{
    /*
     * FIXME: Winchip2 supports uncached
     */
    if (type != MTRR_TYPE_WRCOMB &&
        (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
        pr_warning("mtrr: only write-combining%s supported\n",
               centaur_mcr_type ? " and uncacheable are" : " is");
        return -EINVAL;
    }
    return 0;
}

static const struct mtrr_ops centaur_mtrr_ops = {
    .vendor            = X86_VENDOR_CENTAUR,
    .set               = centaur_set_mcr,
    .get               = centaur_get_mcr,
    .get_free_region   = centaur_get_free_region,
    .validate_add_page = centaur_validate_add_page,
    .have_wrcomb       = positive_have_wrcomb,
};

int __init centaur_init_mtrr(void)
{
    set_mtrr_ops(&centaur_mtrr_ops);
    return 0;
}