net/cadence_gem: Implement SAR match bit in rx desc

Bit 27 of the RX buffer desc word 1 should be set when the packet was
accepted due to specific address register match. Implement.

This feature is absent from the Xilinx documentation (UG585) but the
behaviour is tested as accurate on real hardware.
Reported-by: NDeepika Dhamija <deepika@xilinx.com>
Signed-off-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 7e3f26fc4ab244e8123efc12723e7164730abdcb.1386136219.git.peter.crosthwaite@xilinx.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/net/cadence_gem.c

@@ -243,6 +243,7 @@
 
 #define R_DESC_1_RX_SAR_SHIFT           25
 #define R_DESC_1_RX_SAR_LENGTH          2
+#define R_DESC_1_RX_SAR_MATCH           (1 << 27)
 #define R_DESC_1_RX_UNICAST_HASH        (1 << 29)
 #define R_DESC_1_RX_MULTICAST_HASH      (1 << 30)
 #define R_DESC_1_RX_BROADCAST           (1 << 31)
@@ -345,6 +346,7 @@ static inline void rx_desc_set_sar(unsigned *desc, int sar_idx)
 {
     desc[1] = deposit32(desc[1], R_DESC_1_RX_SAR_SHIFT, R_DESC_1_RX_SAR_LENGTH,
                         sar_idx);
+    desc[1] |= R_DESC_1_RX_SAR_MATCH;
 }
 
 #define TYPE_CADENCE_GEM "cadence_gem"