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, <ype); 41 if (lsize == 0) 42 return i; 43 } 44 45 return -ENOSPC; 46 } 47 48 static void 49 centaur_get_mcr(unsigned int reg, unsigned long *base, 50 unsigned long *size, mtrr_type * type) 51 { 52 *base = centaur_mcr[reg].high >> PAGE_SHIFT; 53 *size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT; 54 *type = MTRR_TYPE_WRCOMB; /* write-combining */ 55 56 if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2)) 57 *type = MTRR_TYPE_UNCACHABLE; 58 if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25) 59 *type = MTRR_TYPE_WRBACK; 60 if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31) 61 *type = MTRR_TYPE_WRBACK; 62 } 63 64 static void 65 centaur_set_mcr(unsigned int reg, unsigned long base, 66 unsigned long size, mtrr_type type) 67 { 68 unsigned long low, high; 69 70 if (size == 0) { 71 /* Disable */ 72 high = low = 0; 73 } else { 74 high = base << PAGE_SHIFT; 75 if (centaur_mcr_type == 0) { 76 /* Only support write-combining... */ 77 low = -size << PAGE_SHIFT | 0x1f; 78 } else { 79 if (type == MTRR_TYPE_UNCACHABLE) 80 low = -size << PAGE_SHIFT | 0x02; /* NC */ 81 else 82 low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */ 83 } 84 } 85 centaur_mcr[reg].high = high; 86 centaur_mcr[reg].low = low; 87 wrmsr(MSR_IDT_MCR0 + reg, low, high); 88 } 89 90 static int 91 centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type) 92 { 93 /* 94 * FIXME: Winchip2 supports uncached 95 */ 96 if (type != MTRR_TYPE_WRCOMB && 97 (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) { 98 pr_warn("mtrr: only write-combining%s supported\n", 99 centaur_mcr_type ? " and uncacheable are" : " is"); 100 return -EINVAL; 101 } 102 return 0; 103 } 104 105 const struct mtrr_ops centaur_mtrr_ops = { 106 .var_regs = 8, 107 .set = centaur_set_mcr, 108 .get = centaur_get_mcr, 109 .get_free_region = centaur_get_free_region, 110 .validate_add_page = centaur_validate_add_page, 111 .have_wrcomb = positive_have_wrcomb, 112 }; 113