powerpc/85xx: Display SERDES 8 erratum warning if banks are not disabled

The work-around for P4080 erratum SERDES-8 requires all lanes of banks two
and three to be disabled (powered down) in the RCW.  Display a warning
message if this is not the case.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/cpu/mpc85xx/fsl_corenet_serdes.c

@@ -475,6 +475,17 @@ void fsl_serdes_init(void)
 	}
 
 #ifdef CONFIG_SYS_P4080_ERRATUM_SERDES8
+	/*
+	 * Display a warning if banks two and three are not disabled in the RCW,
+	 * since our work-around for SERDES8 depends on these banks being
+	 * disabled at power-on.
+	 */
+#define B2_B3 (FSL_CORENET_RCWSRn_SRDS_LPD_B2 | FSL_CORENET_RCWSRn_SRDS_LPD_B3)
+	if ((in_be32(&gur->rcwsr[5]) & B2_B3) != B2_B3) {
+		printf("Warning: SERDES8 requires banks two and "
+		       "three to be disabled in the RCW\n");
+	}
+
 	/*
 	 * Store the values of the fsl_srds_lpd_b2 and fsl_srds_lpd_b3
 	 * hwconfig options into the srds_lpd_b[] array.  See README.p4080ds