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

   1 #include <linux/init.h>
   2 #include <linux/mm.h>
   3
   4 #include <asm/mtrr.h>
   5 #include <asm/msr.h>
   6
   7 #include "mtrr.h"
   8
   9 static struct {
  10         unsigned long high;
  11         unsigned long low;
  12 } centaur_mcr[8];
  13
  14 static u8 centaur_mcr_reserved;
  15 static u8 centaur_mcr_type;     /* 0 for winchip, 1 for winchip2 */
  16
  17 /**
  18  * centaur_get_free_region - Get a free MTRR.
  19  *
  20  * @base: The starting (base) address of the region.
  21  * @size: The size (in bytes) of the region.
  22  *
  23  * Returns: the index of the region on success, else -1 on error.
  24  */
  25 static int
  26 centaur_get_free_region(unsigned long base, unsigned long size, int replace_reg)
  27 {
  28         unsigned long lbase, lsize;
  29         mtrr_type ltype;
  30         int i, max;
  31
  32         max = num_var_ranges;
  33         if (replace_reg >= 0 && replace_reg < max)
  34                 return replace_reg;
  35
  36         for (i = 0; i < max; ++i) {
  37                 if (centaur_mcr_reserved & (1 << i))
  38                         continue;
  39                 mtrr_if->get(i, &lbase, &lsize, &ltype);
  40                 if (lsize == 0)
  41                         return i;
  42         }
  43
  44         return -ENOSPC;
  45 }
  46
  47 /*
  48  * Report boot time MCR setups
  49  */
  50 void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
  51 {
  52         centaur_mcr[mcr].low = lo;
  53         centaur_mcr[mcr].high = hi;
  54 }
  55
  56 static void
  57 centaur_get_mcr(unsigned int reg, unsigned long *base,
  58                 unsigned long *size, mtrr_type * type)
  59 {
  60         *base = centaur_mcr[reg].high >> PAGE_SHIFT;
  61         *size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
  62         *type = MTRR_TYPE_WRCOMB;               /* write-combining  */
  63
  64         if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
  65                 *type = MTRR_TYPE_UNCACHABLE;
  66         if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
  67                 *type = MTRR_TYPE_WRBACK;
  68         if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
  69                 *type = MTRR_TYPE_WRBACK;
  70 }
  71
  72 static void
  73 centaur_set_mcr(unsigned int reg, unsigned long base,
  74                 unsigned long size, mtrr_type type)
  75 {
  76         unsigned long low, high;
  77
  78         if (size == 0) {
  79                 /* Disable */
  80                 high = low = 0;
  81         } else {
  82                 high = base << PAGE_SHIFT;
  83                 if (centaur_mcr_type == 0) {
  84                         /* Only support write-combining... */
  85                         low = -size << PAGE_SHIFT | 0x1f;
  86                 } else {
  87                         if (type == MTRR_TYPE_UNCACHABLE)
  88                                 low = -size << PAGE_SHIFT | 0x02; /* NC */
  89                         else
  90                                 low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
  91                 }
  92         }
  93         centaur_mcr[reg].high = high;
  94         centaur_mcr[reg].low = low;
  95         wrmsr(MSR_IDT_MCR0 + reg, low, high);
  96 }
  97
  98 static int
  99 centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
 100 {
 101         /*
 102          * FIXME: Winchip2 supports uncached
 103          */
 104         if (type != MTRR_TYPE_WRCOMB &&
 105             (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
 106                 pr_warning("mtrr: only write-combining%s supported\n",
 107                            centaur_mcr_type ? " and uncacheable are" : " is");
 108                 return -EINVAL;
 109         }
 110         return 0;
 111 }
 112
 113 static struct mtrr_ops centaur_mtrr_ops = {
 114         .vendor            = X86_VENDOR_CENTAUR,
 115         .set               = centaur_set_mcr,
 116         .get               = centaur_get_mcr,
 117         .get_free_region   = centaur_get_free_region,
 118         .validate_add_page = centaur_validate_add_page,
 119         .have_wrcomb       = positive_have_wrcomb,
 120 };
 121
 122 int __init centaur_init_mtrr(void)
 123 {
 124         set_mtrr_ops(&centaur_mtrr_ops);
 125         return 0;
 126 }