LXR linux/arch/x86/kernel/cpu/mtrr/centaur.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/init.h>
   3#include <linux/mm.h>
   4
   5#include <asm/mtrr.h>
   6#include <asm/msr.h>
   7
   8#include "mtrr.h"
   9
  10static struct {
  11        unsigned long high;
  12        unsigned long low;
  13} centaur_mcr[8];
  14
  15static u8 centaur_mcr_reserved;
  16static u8 centaur_mcr_type;     /* 0 for winchip, 1 for winchip2 */
  17
  18/**
  19 * centaur_get_free_region - Get a free MTRR.
  20 *
  21 * @base: The starting (base) address of the region.
  22 * @size: The size (in bytes) of the region.
  23 *
  24 * Returns: the index of the region on success, else -1 on error.
  25 */
  26static int
  27centaur_get_free_region(unsigned long base, unsigned long size, int replace_reg)
  28{
  29        unsigned long lbase, lsize;
  30        mtrr_type ltype;
  31        int i, max;
  32
  33        max = num_var_ranges;
  34        if (replace_reg >= 0 && replace_reg < max)
  35                return replace_reg;
  36
  37        for (i = 0; i < max; ++i) {
  38                if (centaur_mcr_reserved & (1 << i))
  39                        continue;
  40                mtrr_if->get(i, &lbase, &lsize, &ltype);
  41                if (lsize == 0)
  42                        return i;
  43        }
  44
  45        return -ENOSPC;
  46}
  47
  48/*
  49 * Report boot time MCR setups
  50 */
  51void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
  52{
  53        centaur_mcr[mcr].low = lo;
  54        centaur_mcr[mcr].high = hi;
  55}
  56
  57static void
  58centaur_get_mcr(unsigned int reg, unsigned long *base,
  59                unsigned long *size, mtrr_type * type)
  60{
  61        *base = centaur_mcr[reg].high >> PAGE_SHIFT;
  62        *size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
  63        *type = MTRR_TYPE_WRCOMB;               /* write-combining  */
  64
  65        if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
  66                *type = MTRR_TYPE_UNCACHABLE;
  67        if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
  68                *type = MTRR_TYPE_WRBACK;
  69        if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
  70                *type = MTRR_TYPE_WRBACK;
  71}
  72
  73static void
  74centaur_set_mcr(unsigned int reg, unsigned long base,
  75                unsigned long size, mtrr_type type)
  76{
  77        unsigned long low, high;
  78
  79        if (size == 0) {
  80                /* Disable */
  81                high = low = 0;
  82        } else {
  83                high = base << PAGE_SHIFT;
  84                if (centaur_mcr_type == 0) {
  85                        /* Only support write-combining... */
  86                        low = -size << PAGE_SHIFT | 0x1f;
  87                } else {
  88                        if (type == MTRR_TYPE_UNCACHABLE)
  89                                low = -size << PAGE_SHIFT | 0x02; /* NC */
  90                        else
  91                                low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
  92                }
  93        }
  94        centaur_mcr[reg].high = high;
  95        centaur_mcr[reg].low = low;
  96        wrmsr(MSR_IDT_MCR0 + reg, low, high);
  97}
  98
  99static int
 100centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
 101{
 102        /*
 103         * FIXME: Winchip2 supports uncached
 104         */
 105        if (type != MTRR_TYPE_WRCOMB &&
 106            (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
 107                pr_warn("mtrr: only write-combining%s supported\n",
 108                           centaur_mcr_type ? " and uncacheable are" : " is");
 109                return -EINVAL;
 110        }
 111        return 0;
 112}
 113
 114static const struct mtrr_ops centaur_mtrr_ops = {
 115        .vendor            = X86_VENDOR_CENTAUR,
 116        .set               = centaur_set_mcr,
 117        .get               = centaur_get_mcr,
 118        .get_free_region   = centaur_get_free_region,
 119        .validate_add_page = centaur_validate_add_page,
 120        .have_wrcomb       = positive_have_wrcomb,
 121};
 122
 123int __init centaur_init_mtrr(void)
 124{
 125        set_mtrr_ops(&centaur_mtrr_ops);
 126        return 0;
 127}
 128