git.mutantstargoat.com Git - retroray/blob - src/dos/mtrr.c

   1 #include "mtrr.h"
   2
   3 #define MSR_MTRRCAP                     0xfe
   4 #define MSR_MTRRDEFTYPE         0x2ff
   5 #define MSR_MTRRBASE(x)         (0x200 | ((x) << 1))
   6 #define MSR_MTRRMASK(x)         (0x201 | ((x) << 1))
   7 #define MTRRDEF_EN                      0x800
   8 #define MTRRCAP_HAVE_WC         0x400
   9 #define MTRRMASK_VALID          0x800
  10
  11 static const char *mtrr_type_name(int type);
  12 static void print_mtrr(void);
  13
  14
  15 int get_page_memtype(uint32_t addr, int num_ranges)
  16 {
  17         int i;
  18         uint32_t rlow, rhigh;
  19         uint32_t base, mask;
  20
  21         for(i=0; i<num_ranges; i++) {
  22                 get_msr(MSR_MTRRMASK(i), &rlow, &rhigh);
  23                 if(!(rlow & MTRRMASK_VALID)) {
  24                         continue;
  25                 }
  26                 mask = rlow & 0xfffff000;
  27
  28                 get_msr(MSR_MTRRBASE(i), &rlow, &rhigh);
  29                 base = rlow & 0xfffff000;
  30
  31                 if((addr & mask) == (base & mask)) {
  32                         return rlow & 0xff;
  33                 }
  34         }
  35
  36         get_msr(MSR_MTRRDEFTYPE, &rlow, &rhigh);
  37         return rlow & 0xff;
  38 }
  39
  40 int check_wrcomb_enabled(uint32_t addr, int len, int num_ranges)
  41 {
  42         while(len > 0) {
  43                 if(get_page_memtype(addr, num_ranges) != MTRR_WC) {
  44                         return 0;
  45                 }
  46                 addr += 4096;
  47                 len -= 4096;
  48         }
  49         return 1;
  50 }
  51
  52 int alloc_mtrr(int num_ranges)
  53 {
  54         int i;
  55         uint32_t rlow, rhigh;
  56
  57         for(i=0; i<num_ranges; i++) {
  58                 get_msr(MSR_MTRRMASK(i), &rlow, &rhigh);
  59                 if(!(rlow & MTRRMASK_VALID)) {
  60                         return i;
  61                 }
  62         }
  63         return -1;
  64 }
  65
  66 void enable_wrcomb(uint32_t addr, int len)
  67 {
  68         int num_ranges, mtrr;
  69         uint32_t rlow, rhigh;
  70         uint32_t def, mask;
  71
  72         if(len <= 0 || (addr | (uint32_t)len) & 0xfff) {
  73                 errormsg("failed to enable write combining, unaligned range: %p/%x\n",
  74                                 (void*)addr, (unsigned int)len);
  75                 return;
  76         }
  77
  78         get_msr(MSR_MTRRCAP, &rlow, &rhigh);
  79         num_ranges = rlow & 0xff;
  80
  81         infomsg("enable_wrcomb: addr=%p len=%x\n", (void*)addr, (unsigned int)len);
  82
  83         if(!(rlow & MTRRCAP_HAVE_WC)) {
  84                 errormsg("failed to enable write combining, processor doesn't support it\n");
  85                 return;
  86         }
  87
  88         if(check_wrcomb_enabled(addr, len, num_ranges)) {
  89                 return;
  90         }
  91
  92         if((mtrr = alloc_mtrr(num_ranges)) == -1) {
  93                 errormsg("failed to enable write combining, no free MTRRs\n");
  94                 return;
  95         }
  96
  97         mask = len - 1;
  98         mask |= mask >> 1;
  99         mask |= mask >> 2;
 100         mask |= mask >> 4;
 101         mask |= mask >> 8;
 102         mask |= mask >> 16;
 103         mask = ~mask & 0xfffff000;
 104
 105         infomsg("  ... mask: %08x\n", (unsigned int)mask);
 106
 107         _disable();
 108         get_msr(MSR_MTRRDEFTYPE, &def, &rhigh);
 109         set_msr(MSR_MTRRDEFTYPE, def & ~MTRRDEF_EN, rhigh);
 110
 111         set_msr(MSR_MTRRBASE(mtrr), addr | MTRR_WC, 0);
 112         set_msr(MSR_MTRRMASK(mtrr), mask | MTRRMASK_VALID, 0);
 113
 114         set_msr(MSR_MTRRDEFTYPE, def | MTRRDEF_EN, 0);
 115         _enable();
 116 }
 117
 118 static const char *mtrr_names[] = { "N/A", "W C", "N/A", "N/A", "W T", "W P", "W B" };
 119
 120 static const char *mtrr_type_name(int type)
 121 {
 122         if(type < 0 || type >= sizeof mtrr_names / sizeof *mtrr_names) {
 123                 return mtrr_names[0];
 124         }
 125         return mtrr_names[type];
 126 }
 127
 128 static void print_mtrr(void)
 129 {
 130         int i, num_ranges;
 131         uint32_t rlow, rhigh, base, mask;
 132
 133         get_msr(MSR_MTRRCAP, &rlow, &rhigh);
 134         num_ranges = rlow & 0xff;
 135
 136         for(i=0; i<num_ranges; i++) {
 137                 get_msr(MSR_MTRRBASE(i), &base, &rhigh);
 138                 get_msr(MSR_MTRRMASK(i), &mask, &rhigh);
 139
 140                 if(mask & MTRRMASK_VALID) {
 141                         infomsg("mtrr%d: base %p, mask %08x type %s\n", i, (void*)(base & 0xfffff000),
 142                                         (unsigned int)(mask & 0xfffff000), mtrr_type_name(base & 0xff));
 143                 } else {
 144                         infomsg("mtrr%d unused (%08x/%08x)\n", i, (unsigned int)base,
 145                                         (unsigned int)mask);
 146                 }
 147         }
 148         /*fflush(stdout);*/
 149 }