nb/intel/haswell: Ensure MCH has acked raminit

Haswell MRC.bin can return zero even when raminit did not complete
successfully. When this happens, the memory controller will not have
acknowledged raminit: the mc_init_done_ack bit in the MC_INIT_STATE_G
register will be zero, and memory accesses will lock up the system.

To handle this situation more gracefully, check the mc_init_done_ack bit
after running MRC. If the bit is not set, log a fatal error and halt.

Tested on Asrock B85M Pro4:
- With badly-seated DIMMs, MRC raminit fails and coreboot dies.
- After reseating the DIMMs, the board still boots successfully.

Change-Id: I144bf827f65cd0be319c44bf3d407ddc116b129d
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51940
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/northbridge/intel/haswell/raminit.c

@@ -169,6 +169,16 @@ static void sdram_initialize(struct pei_data *pei_data)
 		(version >> 24) & 0xff, (version >> 16) & 0xff,
 		(version >>  8) & 0xff, (version >>  0) & 0xff);
 
+	/*
+	 * MRC may return zero even when raminit did not complete successfully.
+	 * Ensure the mc_init_done_ack bit is set before continuing. Otherwise,
+	 * attempting to access memory will lock up the system.
+	 */
+	if (!(MCHBAR32(MC_INIT_STATE_G) & (1 << 5))) {
+		printk(BIOS_EMERG, "Memory controller did not acknowledge raminit.\n");
+		die("MRC raminit failed\n");
+	}
+
 	report_memory_config();
 }