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
 48static void
 49centaur_get_mcr(unsigned int reg, unsigned long *base,
 50		unsigned long *size, mtrr_type * type)
 51{
 52	*base = centaur_mcr[reg].high >> PAGE_SHIFT;
 53	*size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
 54	*type = MTRR_TYPE_WRCOMB;		/* write-combining  */
 55
 56	if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
 57		*type = MTRR_TYPE_UNCACHABLE;
 58	if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
 59		*type = MTRR_TYPE_WRBACK;
 60	if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
 61		*type = MTRR_TYPE_WRBACK;
 62}
 63
 64static void
 65centaur_set_mcr(unsigned int reg, unsigned long base,
 66		unsigned long size, mtrr_type type)
 67{
 68	unsigned long low, high;
 69
 70	if (size == 0) {
 71		/* Disable */
 72		high = low = 0;
 73	} else {
 74		high = base << PAGE_SHIFT;
 75		if (centaur_mcr_type == 0) {
 76			/* Only support write-combining... */
 77			low = -size << PAGE_SHIFT | 0x1f;
 78		} else {
 79			if (type == MTRR_TYPE_UNCACHABLE)
 80				low = -size << PAGE_SHIFT | 0x02; /* NC */
 81			else
 82				low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
 83		}
 84	}
 85	centaur_mcr[reg].high = high;
 86	centaur_mcr[reg].low = low;
 87	wrmsr(MSR_IDT_MCR0 + reg, low, high);
 88}
 89
 90static int
 91centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
 92{
 93	/*
 94	 * FIXME: Winchip2 supports uncached
 95	 */
 96	if (type != MTRR_TYPE_WRCOMB &&
 97	    (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
 98		pr_warn("mtrr: only write-combining%s supported\n",
 99			   centaur_mcr_type ? " and uncacheable are" : " is");
100		return -EINVAL;
101	}
102	return 0;
103}
104
105const struct mtrr_ops centaur_mtrr_ops = {
106	.var_regs          = 8,
107	.set               = centaur_set_mcr,
108	.get               = centaur_get_mcr,
109	.get_free_region   = centaur_get_free_region,
110	.validate_add_page = centaur_validate_add_page,
111	.have_wrcomb       = positive_have_wrcomb,
112};