perf/x86/intel/uncore: Update sysfs-devices-mapping file

Add description for /sys/devices/uncore_upi_*/die* attributes to
sysfs-devices-mapping.
Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20221117122833.3103580-11-alexander.antonov@linux.intel.com

Documentation/ABI/testing/sysfs-devices-mapping

 What:           /sys/devices/uncore_iio_x/dieX
 Date:           February 2020
-Contact:        Roman Sudarikov <roman.sudarikov@linux.intel.com>
+Contact:        Alexander Antonov <alexander.antonov@linux.intel.com>
 Description:
                 Each IIO stack (PCIe root port) has its own IIO PMON block, so
                 each dieX file (where X is die number) holds "Segment:Root Bus"
@@ -32,3 +32,31 @@ Description:
 		    IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000
 		    IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000
 		    IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000
+
+What:           /sys/devices/uncore_upi_x/dieX
+Date:           March 2022
+Contact:        Alexander Antonov <alexander.antonov@linux.intel.com>
+Description:
+                Each /sys/devices/uncore_upi_X/dieY file holds "upi_Z,die_W"
+                value that means UPI link number X on die Y is connected to UPI
+                link Z on die W and this link between sockets can be monitored
+                by UPI PMON block.
+                For example, 4-die Sapphire Rapids platform has the following
+                UPI 0 topology::
+
+		    # tail /sys/devices/uncore_upi_0/die*
+		    ==> /sys/devices/uncore_upi_0/die0 <==
+		    upi_1,die_1
+		    ==> /sys/devices/uncore_upi_0/die1 <==
+		    upi_0,die_3
+		    ==> /sys/devices/uncore_upi_0/die2 <==
+		    upi_1,die_3
+		    ==> /sys/devices/uncore_upi_0/die3 <==
+		    upi_0,die_1
+
+                Which means::
+
+		    UPI link 0 on die 0 is connected to UPI link 1 on die 1
+		    UPI link 0 on die 1 is connected to UPI link 0 on die 3
+		    UPI link 0 on die 2 is connected to UPI link 1 on die 3
+		    UPI link 0 on die 3 is connected to UPI link 0 on die 1
\ No newline at end of file