1 files changed, 127 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/centaur.c b/arch/x86/kernel/cpu/mtrr/centaur.c
new file mode 100644
index 000000000..f27177816
--- /dev/null
+++ b/arch/x86/kernel/cpu/mtrr/centaur.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/init.h>
+#include <linux/mm.h>
+
+#include <asm/mtrr.h>
+#include <asm/msr.h>
+
+#include "mtrr.h"
+
+static struct {
+	unsigned long high;
+	unsigned long low;
+} centaur_mcr[8];
+
+static u8 centaur_mcr_reserved;
+static u8 centaur_mcr_type;	/* 0 for winchip, 1 for winchip2 */
+
+/**
+ * centaur_get_free_region - Get a free MTRR.
+ *
+ * @base: The starting (base) address of the region.
+ * @size: The size (in bytes) of the region.
+ *
+ * Returns: the index of the region on success, else -1 on error.
+ */
+static int
+centaur_get_free_region(unsigned long base, unsigned long size, int replace_reg)
+{
+	unsigned long lbase, lsize;
+	mtrr_type ltype;
+	int i, max;
+
+	max = num_var_ranges;
+	if (replace_reg >= 0 && replace_reg < max)
+		return replace_reg;
+
+	for (i = 0; i < max; ++i) {
+		if (centaur_mcr_reserved & (1 << i))
+			continue;
+		mtrr_if->get(i, &lbase, &lsize, &ltype);
+		if (lsize == 0)
+			return i;
+	}
+
+	return -ENOSPC;
+}
+
+/*
+ * Report boot time MCR setups
+ */
+void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
+{
+	centaur_mcr[mcr].low = lo;
+	centaur_mcr[mcr].high = hi;
+}
+
+static void
+centaur_get_mcr(unsigned int reg, unsigned long *base,
+		unsigned long *size, mtrr_type * type)
+{
+	*base = centaur_mcr[reg].high >> PAGE_SHIFT;
+	*size = -(centaur_mcr[reg].low & 0xfffff000) >> PAGE_SHIFT;
+	*type = MTRR_TYPE_WRCOMB;		/* write-combining  */
+
+	if (centaur_mcr_type == 1 && ((centaur_mcr[reg].low & 31) & 2))
+		*type = MTRR_TYPE_UNCACHABLE;
+	if (centaur_mcr_type == 1 && (centaur_mcr[reg].low & 31) == 25)
+		*type = MTRR_TYPE_WRBACK;
+	if (centaur_mcr_type == 0 && (centaur_mcr[reg].low & 31) == 31)
+		*type = MTRR_TYPE_WRBACK;
+}
+
+static void
+centaur_set_mcr(unsigned int reg, unsigned long base,
+		unsigned long size, mtrr_type type)
+{
+	unsigned long low, high;
+
+	if (size == 0) {
+		/* Disable */
+		high = low = 0;
+	} else {
+		high = base << PAGE_SHIFT;
+		if (centaur_mcr_type == 0) {
+			/* Only support write-combining... */
+			low = -size << PAGE_SHIFT | 0x1f;
+		} else {
+			if (type == MTRR_TYPE_UNCACHABLE)
+				low = -size << PAGE_SHIFT | 0x02; /* NC */
+			else
+				low = -size << PAGE_SHIFT | 0x09; /* WWO, WC */
+		}
+	}
+	centaur_mcr[reg].high = high;
+	centaur_mcr[reg].low = low;
+	wrmsr(MSR_IDT_MCR0 + reg, low, high);
+}
+
+static int
+centaur_validate_add_page(unsigned long base, unsigned long size, unsigned int type)
+{
+	/*
+	 * FIXME: Winchip2 supports uncached
+	 */
+	if (type != MTRR_TYPE_WRCOMB &&
+	    (centaur_mcr_type == 0 || type != MTRR_TYPE_UNCACHABLE)) {
+		pr_warn("mtrr: only write-combining%s supported\n",
+			   centaur_mcr_type ? " and uncacheable are" : " is");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static const struct mtrr_ops centaur_mtrr_ops = {
+	.vendor            = X86_VENDOR_CENTAUR,
+	.set               = centaur_set_mcr,
+	.get               = centaur_get_mcr,
+	.get_free_region   = centaur_get_free_region,
+	.validate_add_page = centaur_validate_add_page,
+	.have_wrcomb       = positive_have_wrcomb,
+};
+
+int __init centaur_init_mtrr(void)
+{
+	set_mtrr_ops(&centaur_mtrr_ops);
+	return 0;
+}