1 files changed, 122 insertions, 0 deletions
diff --git a/os/cerf405/mmu.c b/os/cerf405/mmu.c
new file mode 100644
index 00000000..ae0e0be9
--- /dev/null
+++ b/os/cerf405/mmu.c
@@ -0,0 +1,122 @@
+#include	"u.h"
+#include	"../port/lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+
+extern	ulong	tlbtab[], tlbtabe[];
+static	int	tlbx;	/* index of next free entry in TLB */
+
+enum
+{
+	/* on-chip memory dcr */
+	Isarc=	0x018,	/* instruction-side address range compare */
+	Iscntl=	0x019,	/* instruction-side control register */
+	  Isen=		1<<31,	/* enable */
+	Dsarc=	0x01A,	/* data-side address range compare register */
+	Dscntl=	0x01B,	/* data-side control register */
+	  Dsen=		1<<31,	/* enable */
+	  Dof=		1<<30,	/* must be one (p. 5-7) */
+};
+
+void
+mmuinit(void)
+{
+	int i;
+
+	/*
+	 * the l.s initial TLB settings do nearly all that is needed initially.
+	 * clear invalid entries (just for clarity) and record the address
+	 * of the first available
+ 	 */
+	tlbx = -1;
+	for(i = 0; i < 64; i++)
+		if((tlbrehi(i) & TLBVALID) == 0){
+			if(tlbx < 0)
+				tlbx = i;
+			tlbwelo(i, 0);
+			tlbwehi(i, 0);
+		}
+
+	iprint("ccr0=%8.8lux\n", getccr0());
+
+	/*
+	 * set OCM mapping, assuming:
+	 *	caches were invalidated earlier;
+	 *	and we aren't currently using it
+	 * must also set a tlb entry that validates the virtual address but
+	 * the translation is not used (see p. 5-2)
+	 */
+	putdcr(Isarc, OCMZERO);
+	putdcr(Dsarc, OCMZERO);
+	putdcr(Iscntl, Isen);
+	putdcr(Iscntl, Dsen|Dof);
+	tlbwelo(tlbx, OCMZERO|TLBZONE(0)|TLBWR|TLBEX|TLBI);
+	tlbwehi(tlbx, OCMZERO|TLB4K|TLBVALID);
+	tlbx++;
+}
+
+int
+segflush(void *a, ulong n)
+{
+	/* flush dcache then invalidate icache */
+	dcflush(a, n);
+	icflush(a, n);
+	return 0;
+}
+
+/*
+ * return required size and alignment to map n bytes in a tlb entry
+ */
+ulong
+mmumapsize(ulong n)
+{
+	ulong size;
+	int i;
+
+	size = 1024;
+	for(i = 0; i < 8 && size < n; i++)
+		size <<= 2;
+	return size;
+}
+
+/*
+ * map a physical addresses at pa to va, with the given attributes.
+ * the virtual address must not be mapped already.
+ * if va is nil, map it at pa in virtual space.
+ */
+void*
+kmapphys(void *va, ulong pa, ulong nb, ulong attr, ulong le)
+{
+	int s, i;
+	ulong size;
+
+	if(va == nil)
+		va = (void*)pa;	/* simplest is to use a 1-1 map */
+	size = 1024;
+	for(i = 0; i < 8 && size < nb; i++)
+		size <<= 2;
+	if(i >= 8)
+		return nil;
+	s = splhi();
+	tlbwelo(tlbx, pa | TLBZONE(0) | attr);
+	tlbwehi(tlbx, (ulong)va | (i<<7) | TLBVALID | le);
+	tlbx++;
+	splx(s);
+	return va;
+}
+
+/*
+ * return an uncached alias for the memory at a
+ */
+void*
+mmucacheinhib(void *a, ulong nb)
+{
+	ulong p;
+
+	if(a == nil)
+		return nil;
+	dcflush(a, nb);
+	p = PADDR(a);
+	return kmapphys((void*)(KSEG1|p), p, nb, TLBWR | TLBI | TLBG, 0);
+}