arch/x86/kernel/cpu/mtrr/cyrix.c

   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, &ltype);
 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, &ltype);
 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, &ltype);
 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 };