1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/misc/sgi-xp/xp_nofault.S b/drivers/misc/sgi-xp/xp_nofault.S
new file mode 100644
index 000000000000..c13a709c4db5
--- /dev/null
+++ b/drivers/misc/sgi-xp/xp_nofault.S
@@ -0,0 +1,36 @@
+/*
+ * 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.
+ *
+ * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
+ */
+
+
+/*
+ * The xp_nofault_PIOR function takes a pointer to a remote PIO register
+ * and attempts to load and consume a value from it.  This function
+ * will be registered as a nofault code block.  In the event that the
+ * PIO read fails, the MCA handler will force the error to look
+ * corrected and vector to the xp_error_PIOR which will return an error.
+ *
+ * The definition of "consumption" and the time it takes for an MCA
+ * to surface is processor implementation specific.  This code
+ * is sufficient on Itanium through the Montvale processor family.
+ * It may need to be adjusted for future processor implementations.
+ *
+ *      extern int xp_nofault_PIOR(void *remote_register);
+ */
+
+        .global xp_nofault_PIOR
+xp_nofault_PIOR:
+        mov     r8=r0                   // Stage a success return value
+        ld8.acq r9=[r32];;              // PIO Read the specified register
+        adds    r9=1,r9;;               // Add to force consumption
+        srlz.i;;                        // Allow time for MCA to surface
+        br.ret.sptk.many b0;;           // Return success
+
+        .global xp_error_PIOR
+xp_error_PIOR:
+        mov     r8=1                    // Return value of 1
+        br.ret.sptk.many b0;;           // Return failure