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path: root/drivers/char/uv_mmtimer.c
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Diffstat (limited to 'drivers/char/uv_mmtimer.c')
-rw-r--r--drivers/char/uv_mmtimer.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/drivers/char/uv_mmtimer.c b/drivers/char/uv_mmtimer.c
index 867b67be9f0..c7072ba14f4 100644
--- a/drivers/char/uv_mmtimer.c
+++ b/drivers/char/uv_mmtimer.c
@@ -89,13 +89,17 @@ static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
switch (cmd) {
case MMTIMER_GETOFFSET: /* offset of the counter */
/*
- * UV RTC register is on its own page
+ * Starting with HUB rev 2.0, the UV RTC register is
+ * replicated across all cachelines of it's own page.
+ * This allows faster simultaneous reads from a given socket.
+ *
+ * The offset returned is in 64 bit units.
*/
- if (PAGE_SIZE <= (1 << 16))
- ret = ((UV_LOCAL_MMR_BASE | UVH_RTC) & (PAGE_SIZE-1))
- / 8;
+ if (uv_get_min_hub_revision_id() == 1)
+ ret = 0;
else
- ret = -ENOSYS;
+ ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
+ PAGE_SIZE) / 8;
break;
case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
@@ -115,8 +119,8 @@ static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
break;
- case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
- ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
+ case MMTIMER_MMAPAVAIL:
+ ret = 1;
break;
case MMTIMER_GETCOUNTER: