arch/x86/kernel/cpu/mtrr/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
  10 static struct {
  11         unsigned long high;
  12         unsigned long low;
  13 } centaur_mcr[8];
  14
  15 static u8 centaur_mcr_reserved;
  16 static 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  */
  26 static int
  27 centaur_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
  48 /*
  49  * Report boot time MCR setups
  50  */
  51 void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
  52 {
  53         centaur_mcr[mcr].low = lo;
  54         centaur_mcr[mcr].high = hi;
  55 }
  56
  57 static void
  58 centaur_get_mcr(unsigned int reg, unsigned long *base,
  59                 unsigned long *size, mtrr_type * type)
  60 {
  61         *base = centaur_mcr[reg].high >> PAGE_SHIFT;
  62         *size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
  63         *type = MTRR_TYPE_WRCOMB;               /* write-combining  */
  64
  65         if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
  66                 *type = MTRR_TYPE_UNCACHABLE;
  67         if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
  68                 *type = MTRR_TYPE_WRBACK;
  69         if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
  70                 *type = MTRR_TYPE_WRBACK;
  71 }
  72
  73 static void
  74 centaur_set_mcr(unsigned int reg, unsigned long base,
  75                 unsigned long size, mtrr_type type)
  76 {
  77         unsigned long low, high;
  78
  79         if (size == 0) {
  80                 /* Disable */
  81                 high = low = 0;
  82         } else {
  83                 high = base << PAGE_SHIFT;
  84                 if (centaur_mcr_type == 0) {
  85                         /* Only support write-combining... */
  86                         low = -size << PAGE_SHIFT | 0x1f;
  87                 } else {
  88                         if (type == MTRR_TYPE_UNCACHABLE)
  89                                 low = -size << PAGE_SHIFT | 0x02; /* NC */
  90                         else
  91                                 low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
  92                 }
  93         }
  94         centaur_mcr[reg].high = high;
  95         centaur_mcr[reg].low = low;
  96         wrmsr(MSR_IDT_MCR0 + reg, low, high);
  97 }
  98
  99 static int
 100 centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
 101 {
 102         /*
 103          * FIXME: Winchip2 supports uncached
 104          */
 105         if (type != MTRR_TYPE_WRCOMB &&
 106             (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
 107                 pr_warn("mtrr: only write-combining%s supported\n",
 108                            centaur_mcr_type ? " and uncacheable are" : " is");
 109                 return -EINVAL;
 110         }
 111         return 0;
 112 }
 113
 114 static const struct mtrr_ops centaur_mtrr_ops = {
 115         .vendor            = X86_VENDOR_CENTAUR,
 116         .set               = centaur_set_mcr,
 117         .get               = centaur_get_mcr,
 118         .get_free_region   = centaur_get_free_region,
 119         .validate_add_page = centaur_validate_add_page,
 120         .have_wrcomb       = positive_have_wrcomb,
 121 };
 122
 123 int __init centaur_init_mtrr(void)
 124 {
 125         set_mtrr_ops(&centaur_mtrr_ops);
 126         return 0;
 127 }