+
+/*
+ * This is the core of clock_gettime(), it returns the current
+ * time in seconds and nanoseconds in r3 and r4.
+ * It expects the datapage ptr in r9 and doesn't clobber it.
+ * It clobbers r0, r5, r6, r10 and returns NSEC_PER_SEC in r7.
+ * On return, r8 contains the counter value that can be reused.
+ * This clobbers cr0 but not any other cr field.
+ */
+__do_get_tspec:
+ .cfi_startproc
+ /* Check for update count & load values. We use the low
+ * order 32 bits of the update count
+ */
+1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
+ andi. r0,r8,1 /* pending update ? loop */
+ bne- 1b
+ xor r0,r8,r8 /* create dependency */
+ add r9,r9,r0
+
+ /* Load orig stamp (offset to TB) */
+ lwz r5,CFG_TB_ORIG_STAMP(r9)
+ lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
+
+ /* Get a stable TB value */
+2: mftbu r3
+ mftbl r4
+ mftbu r0
+ cmpl cr0,r3,r0
+ bne- 2b
+
+ /* Subtract tb orig stamp and shift left 12 bits.
+ */
+ subfc r7,r6,r4
+ subfe r0,r5,r3
+ slwi r0,r0,12
+ rlwimi. r0,r7,12,20,31
+ slwi r7,r7,12
+
+ /* Load scale factor & do multiplication */
+ lwz r5,CFG_TB_TO_XS(r9) /* load values */
+ lwz r6,(CFG_TB_TO_XS+4)(r9)
+ mulhwu r3,r7,r6
+ mullw r10,r7,r5
+ mulhwu r4,r7,r5
+ addc r10,r3,r10
+ li r3,0
+
+ beq+ 4f /* skip high part computation if 0 */
+ mulhwu r3,r0,r5
+ mullw r7,r0,r5
+ mulhwu r5,r0,r6
+ mullw r6,r0,r6
+ adde r4,r4,r7
+ addze r3,r3
+ addc r4,r4,r5
+ addze r3,r3
+ addc r10,r10,r6
+
+4: addze r4,r4 /* add in carry */
+ lis r7,NSEC_PER_SEC@h
+ ori r7,r7,NSEC_PER_SEC@l
+ mulhwu r4,r4,r7 /* convert to nanoseconds */
+
+ /* At this point, we have seconds & nanoseconds since the xtime
+ * stamp in r3+CA and r4. Load & add the xtime stamp.
+ */
+#ifdef CONFIG_PPC64
+ lwz r5,STAMP_XTIME+TSPC64_TV_SEC+LOPART(r9)
+ lwz r6,STAMP_XTIME+TSPC64_TV_NSEC+LOPART(r9)
+#else
+ lwz r5,STAMP_XTIME+TSPC32_TV_SEC(r9)
+ lwz r6,STAMP_XTIME+TSPC32_TV_NSEC(r9)
+#endif
+ add r4,r4,r6
+ adde r3,r3,r5
+
+ /* We now have our result in r3,r4. We create a fake dependency
+ * on that result and re-check the counter
+ */
+ or r6,r4,r3
+ xor r0,r6,r6
+ add r9,r9,r0
+ lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
+ cmpl cr0,r8,r0 /* check if updated */
+ bne- 1b
+
+ /* check for nanosecond overflow and adjust if necessary */
+ cmpw r4,r7
+ bltlr /* all done if no overflow */
+ subf r4,r7,r4 /* adjust if overflow */
+ addi r3,r3,1
+
+ blr
+ .cfi_endproc