1// SPDX-License-Identifier: GPL-2.0-only
 2
 3#include <linux/types.h>
 4#include <linux/slab.h>
 5#include <linux/syscore_ops.h>
 6#include <asm/cpufeature.h>
 7#include <asm/mtrr.h>
 8#include <asm/processor.h>
 9#include "mtrr.h"
10
11void mtrr_set_if(void)
12{
13	switch (boot_cpu_data.x86_vendor) {
14	case X86_VENDOR_AMD:
15		/* Pre-Athlon (K6) AMD CPU MTRRs */
16		if (cpu_feature_enabled(X86_FEATURE_K6_MTRR))
17			mtrr_if = &amd_mtrr_ops;
18		break;
19	case X86_VENDOR_CENTAUR:
20		if (cpu_feature_enabled(X86_FEATURE_CENTAUR_MCR))
21			mtrr_if = &centaur_mtrr_ops;
22		break;
23	case X86_VENDOR_CYRIX:
24		if (cpu_feature_enabled(X86_FEATURE_CYRIX_ARR))
25			mtrr_if = &cyrix_mtrr_ops;
26		break;
27	default:
28		break;
29	}
30}
31
32/*
33 * The suspend/resume methods are only for CPUs without MTRR. CPUs using generic
34 * MTRR driver don't require this.
35 */
36struct mtrr_value {
37	mtrr_type	ltype;
38	unsigned long	lbase;
39	unsigned long	lsize;
40};
41
42static struct mtrr_value *mtrr_value;
43
44static int mtrr_save(void)
45{
46	int i;
47
48	if (!mtrr_value)
49		return -ENOMEM;
50
51	for (i = 0; i < num_var_ranges; i++) {
52		mtrr_if->get(i, &mtrr_value[i].lbase,
53				&mtrr_value[i].lsize,
54				&mtrr_value[i].ltype);
55	}
56	return 0;
57}
58
59static void mtrr_restore(void)
60{
61	int i;
62
63	for (i = 0; i < num_var_ranges; i++) {
64		if (mtrr_value[i].lsize) {
65			mtrr_if->set(i, mtrr_value[i].lbase,
66				     mtrr_value[i].lsize,
67				     mtrr_value[i].ltype);
68		}
69	}
70}
71
72static struct syscore_ops mtrr_syscore_ops = {
73	.suspend	= mtrr_save,
74	.resume		= mtrr_restore,
75};
76
77void mtrr_register_syscore(void)
78{
79	mtrr_value = kcalloc(num_var_ranges, sizeof(*mtrr_value), GFP_KERNEL);
80
81	/*
82	 * The CPU has no MTRR and seems to not support SMP. They have
83	 * specific drivers, we use a tricky method to support
84	 * suspend/resume for them.
85	 *
86	 * TBD: is there any system with such CPU which supports
87	 * suspend/resume? If no, we should remove the code.
88	 */
89	register_syscore_ops(&mtrr_syscore_ops);
90}