1 files changed, 93 insertions, 0 deletions
diff --git a/arch/sh/mm/tlb-urb.c b/arch/sh/mm/tlb-urb.c
new file mode 100644
index 000000000000..c92ce20db39b
--- /dev/null
+++ b/arch/sh/mm/tlb-urb.c
@@ -0,0 +1,93 @@
+/*
+ * arch/sh/mm/tlb-urb.c
+ *
+ * TLB entry wiring helpers for URB-equipped parts.
+ *
+ * Copyright (C) 2010  Matt Fleming
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/mm.h>
+#include <linux/io.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+
+/*
+ * Load the entry for 'addr' into the TLB and wire the entry.
+ */
+void tlb_wire_entry(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
+{
+	unsigned long status, flags;
+	int urb;
+
+	local_irq_save(flags);
+
+	status = __raw_readl(MMUCR);
+	urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
+	status &= ~MMUCR_URC;
+
+	/*
+	 * Make sure we're not trying to wire the last TLB entry slot.
+	 */
+	BUG_ON(!--urb);
+
+	urb = urb % MMUCR_URB_NENTRIES;
+
+	/*
+	 * Insert this entry into the highest non-wired TLB slot (via
+	 * the URC field).
+	 */
+	status |= (urb << MMUCR_URC_SHIFT);
+	__raw_writel(status, MMUCR);
+	ctrl_barrier();
+
+	/* Load the entry into the TLB */
+	__update_tlb(vma, addr, pte);
+
+	/* ... and wire it up. */
+	status = __raw_readl(MMUCR);
+
+	status &= ~MMUCR_URB;
+	status |= (urb << MMUCR_URB_SHIFT);
+
+	__raw_writel(status, MMUCR);
+	ctrl_barrier();
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Unwire the last wired TLB entry.
+ *
+ * It should also be noted that it is not possible to wire and unwire
+ * TLB entries in an arbitrary order. If you wire TLB entry N, followed
+ * by entry N+1, you must unwire entry N+1 first, then entry N. In this
+ * respect, it works like a stack or LIFO queue.
+ */
+void tlb_unwire_entry(void)
+{
+	unsigned long status, flags;
+	int urb;
+
+	local_irq_save(flags);
+
+	status = __raw_readl(MMUCR);
+	urb = (status & MMUCR_URB) >> MMUCR_URB_SHIFT;
+	status &= ~MMUCR_URB;
+
+	/*
+	 * Make sure we're not trying to unwire a TLB entry when none
+	 * have been wired.
+	 */
+	BUG_ON(urb++ == MMUCR_URB_NENTRIES);
+
+	urb = urb % MMUCR_URB_NENTRIES;
+
+	status |= (urb << MMUCR_URB_SHIFT);
+	__raw_writel(status, MMUCR);
+	ctrl_barrier();
+
+	local_irq_restore(flags);
+}