google/eve: Limit memory SKU 5 to 1600MHz

Due to issues with stability limit the SKU with K4EBE304EB-EGCF
memory to 1600MHz instead of 1866MHz.

BUG=b:37172778
BRANCH=none
TEST=pass stress testing on devices with this memory

Change-Id: I02af7e9c35e2c5b0b85223d58025cbd29841d973
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/19227
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/eve/romstage.c

@@ -18,6 +18,7 @@
 #include <stddef.h>
 #include <fsp/soc_binding.h>
 #include <soc/romstage.h>
+#include <console/console.h>
 #include "spd/spd.h"
 
 void mainboard_memory_init_params(FSPM_UPD *mupd)
@@ -46,4 +47,10 @@ void mainboard_memory_init_params(FSPM_UPD *mupd)
 	mem_cfg->MemorySpdPtr00 = mainboard_get_spd_data();
 	mem_cfg->MemorySpdPtr10 = mem_cfg->MemorySpdPtr00;
 	mem_cfg->MemorySpdDataLen = SPD_LEN;
+
+	/* Limit K4EBE304EB-EGCF memory to 1600MHz for stability */
+	if (mainboard_get_spd_index() == 5) {
+		printk(BIOS_WARNING, "Limiting memory to 1600MHz\n");
+		mem_cfg->DdrFreqLimit = 1600;
+	}
 }

src/mainboard/google/eve/spd/spd.c

@@ -77,20 +77,24 @@ static void mainboard_print_spd_info(uint8_t spd[])
 	}
 }
 
-uintptr_t mainboard_get_spd_data(void)
+int mainboard_get_spd_index(void)
 {
-	char *spd_file;
-	size_t spd_file_len;
-	int spd_index;
-
 	gpio_t spd_gpios[] = {
 		GPIO_MEM_CONFIG_0,
 		GPIO_MEM_CONFIG_1,
 		GPIO_MEM_CONFIG_2,
 		GPIO_MEM_CONFIG_3,
 	};
+	return gpio_base2_value(spd_gpios, ARRAY_SIZE(spd_gpios));
+}
 
-	spd_index = gpio_base2_value(spd_gpios, ARRAY_SIZE(spd_gpios));
+uintptr_t mainboard_get_spd_data(void)
+{
+	char *spd_file;
+	size_t spd_file_len;
+	int spd_index;
+
+	spd_index = mainboard_get_spd_index();
 	printk(BIOS_INFO, "SPD index %d\n", spd_index);
 
 	/* Load SPD data from CBFS */

src/mainboard/google/eve/spd/spd.h

@@ -30,6 +30,7 @@
 #define  SPD_PART_LEN		18
 #define SPD_MANU_OFF		148
 
+int mainboard_get_spd_index(void);
 uintptr_t mainboard_get_spd_data(void);
 
 #endif