1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/init.h>
3 #include <linux/io.h>
4 #include <linux/mm.h>
5
6 #include <asm/processor-cyrix.h>
7 #include <asm/processor-flags.h>
8 #include <asm/mtrr.h>
9 #include <asm/msr.h>
10
11 #include "mtrr.h"
12
13 static void
14 cyrix_get_arr(unsigned int reg, unsigned long *base,
15 unsigned long *size, mtrr_type * type)
16 {
17 unsigned char arr, ccr3, rcr, shift;
18 unsigned long flags;
19
20 arr = CX86_ARR_BASE + (reg << 1) + reg; /* avoid multiplication by 3 */
21
22 local_irq_save(flags);
23
24 ccr3 = getCx86(CX86_CCR3);
25 setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10); /* enable MAPEN */
26 ((unsigned char *)base)[3] = getCx86(arr);
27 ((unsigned char *)base)[2] = getCx86(arr + 1);
28 ((unsigned char *)base)[1] = getCx86(arr + 2);
29 rcr = getCx86(CX86_RCR_BASE + reg);
30 setCx86(CX86_CCR3, ccr3); /* disable MAPEN */
31
32 local_irq_restore(flags);
33
34 shift = ((unsigned char *) base)[1] & 0x0f;
35 *base >>= PAGE_SHIFT;
36
37 /*
38 * Power of two, at least 4K on ARR0-ARR6, 256K on ARR7
39 * Note: shift==0xf means 4G, this is unsupported.
40 */
41 if (shift)
42 *size = (reg < 7 ? 0x1UL : 0x40UL) << (shift - 1);
43 else
44 *size = 0;
45
46 /* Bit 0 is Cache Enable on ARR7, Cache Disable on ARR0-ARR6 */
47 if (reg < 7) {
48 switch (rcr) {
49 case 1:
50 *type = MTRR_TYPE_UNCACHABLE;
51 break;
52 case 8:
53 *type = MTRR_TYPE_WRBACK;
54 break;
55 case 9:
56 *type = MTRR_TYPE_WRCOMB;
57 break;
58 case 24:
59 default:
60 *type = MTRR_TYPE_WRTHROUGH;
61 break;
62 }
63 } else {
64 switch (rcr) {
65 case 0:
66 *type = MTRR_TYPE_UNCACHABLE;
67 break;
68 case 8:
69 *type = MTRR_TYPE_WRCOMB;
70 break;
71 case 9:
72 *type = MTRR_TYPE_WRBACK;
73 break;
74 case 25:
75 default:
76 *type = MTRR_TYPE_WRTHROUGH;
77 break;
78 }
79 }
80 }
81
82 /*
83 * cyrix_get_free_region - get a free ARR.
84 *
85 * @base: the starting (base) address of the region.
86 * @size: the size (in bytes) of the region.
87 *
88 * Returns: the index of the region on success, else -1 on error.
89 */
90 static int
91 cyrix_get_free_region(unsigned long base, unsigned long size, int replace_reg)
92 {
93 unsigned long lbase, lsize;
94 mtrr_type ltype;
95 int i;
96
97 switch (replace_reg) {
98 case 7:
99 if (size < 0x40)
100 break;
101 fallthrough;
102 case 6:
103 case 5:
104 case 4:
105 return replace_reg;
106 case 3:
107 case 2:
108 case 1:
109 case 0:
110 return replace_reg;
111 }
112 /* If we are to set up a region >32M then look at ARR7 immediately */
113 if (size > 0x2000) {
114 cyrix_get_arr(7, &lbase, &lsize, <ype);
115 if (lsize == 0)
116 return 7;
117 /* Else try ARR0-ARR6 first */
118 } else {
119 for (i = 0; i < 7; i++) {
120 cyrix_get_arr(i, &lbase, &lsize, <ype);
121 if (lsize == 0)
122 return i;
123 }
124 /*
125 * ARR0-ARR6 isn't free
126 * try ARR7 but its size must be at least 256K
127 */
128 cyrix_get_arr(i, &lbase, &lsize, <ype);
129 if ((lsize == 0) && (size >= 0x40))
130 return i;
131 }
132 return -ENOSPC;
133 }
134
135 static u32 cr4, ccr3;
136
137 static void prepare_set(void)
138 {
139 u32 cr0;
140
141 /* Save value of CR4 and clear Page Global Enable (bit 7) */
142 if (boot_cpu_has(X86_FEATURE_PGE)) {
143 cr4 = __read_cr4();
144 __write_cr4(cr4 & ~X86_CR4_PGE);
145 }
146
147 /*
148 * Disable and flush caches.
149 * Note that wbinvd flushes the TLBs as a side-effect
150 */
151 cr0 = read_cr0() | X86_CR0_CD;
152 wbinvd();
153 write_cr0(cr0);
154 wbinvd();
155
156 /* Cyrix ARRs - everything else was excluded at the top */
157 ccr3 = getCx86(CX86_CCR3);
158
159 /* Cyrix ARRs - everything else was excluded at the top */
160 setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
161 }
162
163 static void post_set(void)
164 {
165 /* Flush caches and TLBs */
166 wbinvd();
167
168 /* Cyrix ARRs - everything else was excluded at the top */
169 setCx86(CX86_CCR3, ccr3);
170
171 /* Enable caches */
172 write_cr0(read_cr0() & ~X86_CR0_CD);
173
174 /* Restore value of CR4 */
175 if (boot_cpu_has(X86_FEATURE_PGE))
176 __write_cr4(cr4);
177 }
178
179 static void cyrix_set_arr(unsigned int reg, unsigned long base,
180 unsigned long size, mtrr_type type)
181 {
182 unsigned char arr, arr_type, arr_size;
183
184 arr = CX86_ARR_BASE + (reg << 1) + reg; /* avoid multiplication by 3 */
185
186 /* count down from 32M (ARR0-ARR6) or from 2G (ARR7) */
187 if (reg >= 7)
188 size >>= 6;
189
190 size &= 0x7fff; /* make sure arr_size <= 14 */
191 for (arr_size = 0; size; arr_size++, size >>= 1)
192 ;
193
194 if (reg < 7) {
195 switch (type) {
196 case MTRR_TYPE_UNCACHABLE:
197 arr_type = 1;
198 break;
199 case MTRR_TYPE_WRCOMB:
200 arr_type = 9;
201 break;
202 case MTRR_TYPE_WRTHROUGH:
203 arr_type = 24;
204 break;
205 default:
206 arr_type = 8;
207 break;
208 }
209 } else {
210 switch (type) {
211 case MTRR_TYPE_UNCACHABLE:
212 arr_type = 0;
213 break;
214 case MTRR_TYPE_WRCOMB:
215 arr_type = 8;
216 break;
217 case MTRR_TYPE_WRTHROUGH:
218 arr_type = 25;
219 break;
220 default:
221 arr_type = 9;
222 break;
223 }
224 }
225
226 prepare_set();
227
228 base <<= PAGE_SHIFT;
229 setCx86(arr + 0, ((unsigned char *)&base)[3]);
230 setCx86(arr + 1, ((unsigned char *)&base)[2]);
231 setCx86(arr + 2, (((unsigned char *)&base)[1]) | arr_size);
232 setCx86(CX86_RCR_BASE + reg, arr_type);
233
234 post_set();
235 }
236
237 const struct mtrr_ops cyrix_mtrr_ops = {
238 .var_regs = 8,
239 .set = cyrix_set_arr,
240 .get = cyrix_get_arr,
241 .get_free_region = cyrix_get_free_region,
242 .validate_add_page = generic_validate_add_page,
243 .have_wrcomb = positive_have_wrcomb,
244 };
245
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