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};
113