device/dram/ddr2.c: Improve error returning and debug output

This patch outputs decoding errors with BIOS_WARNING instead of
depending on CONFIG_DEBUG_RAM_SETUP.

Returns SPD_STATUS_INVALID on invalid settings for tRR, bcd and tCK
and doesn't try to create a valid setting if an invalid setting is
detected.

Change-Id: Iee434d1fa1a9d911cc3683b88b260881ed6434ea
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/21480
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

1 files changed, 99 insertions, 39 deletions

diff --git a/src/device/dram/ddr2.c b/src/device/dram/ddr2.c
index 76524ceada..6f43563b6e 100644
--- a/src/device/dram/ddr2.c
+++ b/src/device/dram/ddr2.c
@@ -113,7 +113,7 @@ u8 spd_get_msbs(u8 c)
  * Decodes a raw SPD data from a DDR2 DIMM.
  * Returns cycle time in 1/256th ns.
  */
-static u32 spd_decode_tck_time(u8 c)
+static int spd_decode_tck_time(u32 *tck, u8 c)
 {
 	u8 high, low;
 
@@ -132,11 +132,17 @@ static u32 spd_decode_tck_time(u8 c)
 	case 0xd:
 		low = 75;
 		break;
+	case 0xe:
+	case 0xf:
+		printk(BIOS_WARNING, "Invalid tck setting. "
+			"lower nibble is 0x%x\n", c & 0xf);
+		return CB_ERR;
 	default:
 		low = (c & 0xf) * 10;
 	}
 
-	return ((high * 100 + low) << 8) / 100;
+	*tck = ((high * 100 + low) << 8) / 100;
+	return CB_SUCCESS;
 }
 
 /**
@@ -145,14 +151,17 @@ static u32 spd_decode_tck_time(u8 c)
  * Decodes a raw SPD data from a DDR2 DIMM.
  * Returns cycle time in 1/256th ns.
  */
-static u32 spd_decode_bcd_time(u8 c)
+static int spd_decode_bcd_time(u32 *bcd, u8 c)
 {
 	u8 high, low;
 
 	high = c >> 4;
 	low = c & 0xf;
+	if (high >= 10 || low >= 10)
+		return CB_ERR;
 
-	return ((high * 10 + low) << 8) / 100;
+	*bcd = ((high * 10 + low) << 8) / 100;
+	return CB_SUCCESS;
 }
 
 /**
@@ -177,26 +186,26 @@ static u32 spd_decode_quarter_time(u8 c)
  * Decodes a raw SPD data from a DDR2 DIMM.
  * Returns cycle time in 1/256th us.
  */
-static u32 spd_decode_tRR_time(u8 c)
+static int spd_decode_tRR_time(u32 *tRR, u8 c)
 {
 	switch (c) {
 	default:
-		printk(BIOS_WARNING,
-			"Unknown tRR value, using default of 15.6us.");
-		/* Fallthrough */
+		printk(BIOS_WARNING, "Invalid tRR value 0x%x\n", c);
+		return CB_ERR;
 	case 0x80:
-		return 15625 << 8;
+		*tRR = 15625 << 8;
 	case 0x81:
-		return 15625 << 6;
+		*tRR = 15625 << 6;
 	case 0x82:
-		return 15625 << 7;
+		*tRR = 15625 << 7;
 	case 0x83:
-		return 15625 << 9;
+		*tRR = 15625 << 9;
 	case 0x84:
-		return 15625 << 10;
+		*tRR = 15625 << 10;
 	case 0x85:
-		return 15625 << 11;
+		*tRR = 15625 << 11;
 	}
+	return CB_SUCCESS;
 }
 
 /**
@@ -297,21 +306,22 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	printram("SPD contains 0x%02x bytes\n", spd_size);
 
 	if (spd_size < 64 || eeprom_size < 64) {
-		printram("ERROR: SPD to small\n");
+		printk(BIOS_WARNING, "ERROR: SPD to small\n");
 		dimm->dram_type = SPD_MEMORY_TYPE_UNDEFINED;
 		return SPD_STATUS_INVALID;
 	}
 
 	if (spd_ddr2_calc_checksum(spd, spd_size) != spd[63]) {
-		printram("ERROR: SPD checksum error\n");
+		printk(BIOS_WARNING, "ERROR: SPD checksum error\n");
 		dimm->dram_type = SPD_MEMORY_TYPE_UNDEFINED;
 		return SPD_STATUS_CRC_ERROR;
 	}
 
 	reg8 = spd[62];
 	if ((reg8 & 0xf0) != 0x10) {
-		printram("ERROR: Unsupported SPD revision %01x.%01x\n",
-				reg8 >> 4, reg8 & 0xf);
+		printk(BIOS_WARNING,
+			"ERROR: Unsupported SPD revision %01x.%01x\n",
+			reg8 >> 4, reg8 & 0xf);
 		dimm->dram_type = SPD_MEMORY_TYPE_UNDEFINED;
 		return SPD_STATUS_INVALID;
 	}
@@ -321,7 +331,7 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	reg8 = spd[2];
 	printram("  Type               : 0x%02x\n", reg8);
 	if (reg8 != 0x08) {
-		printram("ERROR: Unsupported SPD type %x\n", reg8);
+		printk(BIOS_WARNING, "ERROR: Unsupported SPD type %x\n", reg8);
 		dimm->dram_type = SPD_MEMORY_TYPE_UNDEFINED;
 		return SPD_STATUS_INVALID;
 	}
@@ -331,14 +341,16 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	printram("  Rows               : %u\n", dimm->row_bits);
 	if ((dimm->row_bits > 31) ||
 	    ((dimm->row_bits > 15) && (dimm->rev < 0x13))) {
-		printram("  Invalid number of memory rows\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid number of memory rows\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
 	dimm->col_bits = spd[4];
 	printram("  Columns            : %u\n", dimm->col_bits);
 	if (dimm->col_bits > 15) {
-		printram("  Invalid number of memory columns\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid number of memory columns\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
@@ -348,21 +360,22 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	dimm->mod_width = spd[6];
 	printram("  Module data width  : x%u\n", dimm->mod_width);
 	if (!dimm->mod_width) {
-		printram("  Invalid module data width\n");
+		printk(BIOS_WARNING, "SPD decode: invalid module data width\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
 	dimm->width = spd[13];
 	printram("  SDRAM width        : x%u\n", dimm->width);
 	if (!dimm->width) {
-		printram("  Invalid SDRAM width\n");
+		printk(BIOS_WARNING, "SPD decode: invalid SDRAM width\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
 	dimm->banks = spd[17];
 	printram("  Banks              : %u\n", dimm->banks);
 	if (!dimm->banks) {
-		printram("  Invalid module banks count\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid module banks count\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
@@ -392,23 +405,26 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 		printram("  Voltage            : 1.8V\n");
 		break;
 	default:
-		printram("  Unknown voltage level.\n");
+		printk(BIOS_WARNING, "SPD decode: unknown voltage level.\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
 	dimm->cas_supported = spd[18];
 	if ((dimm->cas_supported & 0x3) || !dimm->cas_supported) {
-		printram("  Invalid CAS support advertised.\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid CAS support advertised.\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 	printram("  Supported CAS mask : 0x%x\n", dimm->cas_supported);
 
 	if ((dimm->rev < 0x13) && (dimm->cas_supported & 0x80)) {
-		printram("  Invalid CAS support advertised.\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid CAS support advertised.\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 	if ((dimm->rev < 0x12) && (dimm->cas_supported & 0x40)) {
-		printram("  Invalid CAS support advertised.\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid CAS support advertised.\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
@@ -416,26 +432,60 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	cl = spd_get_msbs(dimm->cas_supported);
 
 	/* SDRAM Cycle time at Maximum Supported CAS Latency (CL), CL=X */
-	dimm->cycle_time[cl] = spd_decode_tck_time(spd[9]);
+	if (spd_decode_tck_time(&dimm->cycle_time[cl], spd[9]) != CB_SUCCESS) {
+		printk(BIOS_WARNING,
+			"SPD decode: invalid min tCL for CAS%d\n", cl);
+		ret = SPD_STATUS_INVALID_FIELD;
+	}
 	/* SDRAM Access from Clock */
-	dimm->access_time[cl] = spd_decode_bcd_time(spd[10]);
+	if (spd_decode_bcd_time(&dimm->access_time[cl], spd[10])
+			!= CB_SUCCESS) {
+		printk(BIOS_WARNING,
+			"SPD decode: invalid min tAC for CAS%d\n", cl);
+		ret = SPD_STATUS_INVALID_FIELD;
+	}
 
 	if (dimm->cas_supported & (1 << (cl - 1))) {
 		/* Minimum Clock Cycle at CLX-1 */
-		dimm->cycle_time[cl - 1] = spd_decode_tck_time(spd[23]);
+		if (spd_decode_tck_time(&dimm->cycle_time[cl - 1], spd[23])
+				!= CB_SUCCESS) {
+			printk(BIOS_WARNING,
+				"SPD decode: invalid min tCL for CAS%d\n",
+				cl - 1);
+			ret = SPD_STATUS_INVALID_FIELD;
+		}
 		/* Maximum Data Access Time (tAC) from Clock at CLX-1 */
-		dimm->access_time[cl - 1] = spd_decode_bcd_time(spd[24]);
+		if (spd_decode_bcd_time(&dimm->access_time[cl - 1], spd[24])
+				!= CB_SUCCESS) {
+			printk(BIOS_WARNING,
+				"SPD decode: invalid min tAC for CAS%d\n",
+				cl - 1);
+			ret = SPD_STATUS_INVALID_FIELD;
+		}
 	}
 	if (dimm->cas_supported & (1 << (cl - 2))) {
 		/* Minimum Clock Cycle at CLX-2 */
-		dimm->cycle_time[cl - 2] = spd_decode_tck_time(spd[25]);
+		if (spd_decode_tck_time(&dimm->cycle_time[cl - 2], spd[25])
+				!= CB_SUCCESS) {
+			printk(BIOS_WARNING,
+				"SPD decode: invalid min tCL for CAS%d\n",
+				cl - 2);
+			ret = SPD_STATUS_INVALID_FIELD;
+		}
 		/* Maximum Data Access Time (tAC) from Clock at CLX-2 */
-		dimm->access_time[cl - 2] = spd_decode_bcd_time(spd[26]);
+		if (spd_decode_bcd_time(&dimm->access_time[cl - 2], spd[26])
+				!= CB_SUCCESS) {
+			printk(BIOS_WARNING,
+				"SPD decode: invalid min tAC for CAS%d\n",
+				cl - 2);
+			ret = SPD_STATUS_INVALID_FIELD;
+		}
 	}
 
 	reg8 = (spd[31] >> 5) | (spd[31] << 3);
 	if (!reg8) {
-		printram("  Invalid rank density.\n");
+		printk(BIOS_WARNING,
+			"SPD decode: invalid rank density.\n");
 		ret = SPD_STATUS_INVALID_FIELD;
 	}
 
@@ -449,7 +499,10 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 		printram("  Capacity           : %u GB\n", dimm->size_mb >> 10);
 
 	/* SDRAM Maximum Cycle Time (tCKmax) */
-	dimm->tCK = spd_decode_tck_time(spd[43]);
+	if (spd_decode_bcd_time(&dimm->tCK, spd[43]) != CB_SUCCESS) {
+		printk(BIOS_WARNING, "SPD decode: invalid Max tCK\n");
+		ret = SPD_STATUS_INVALID_FIELD;
+	}
 	/* Minimum Write Recovery Time (tWRmin) */
 	dimm->tWR = spd_decode_quarter_time(spd[36]);
 	/* Minimum RAS# to CAS# Delay Time (tRCDmin) */
@@ -468,9 +521,15 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	/* Minimum Internal Read to Precharge Command Delay Time (tRTPmin) */
 	dimm->tRTP = spd_decode_quarter_time(spd[38]);
 	/* Data Input Setup Time Before Strobe */
-	dimm->tDS = spd_decode_bcd_time(spd[34]);
+	if (spd_decode_bcd_time(&dimm->tDS, spd[34]) != CB_SUCCESS) {
+		printk(BIOS_WARNING, "SPD decode: invalid tDS\n");
+		ret = SPD_STATUS_INVALID_FIELD;
+	}
 	/* Data Input Hold Time After Strobe */
-	dimm->tDH = spd_decode_bcd_time(spd[35]);
+	if (spd_decode_bcd_time(&dimm->tDH, spd[35]) != CB_SUCCESS) {
+		printk(BIOS_WARNING, "SPD decode: invalid tDH\n");
+		ret = SPD_STATUS_INVALID_FIELD;
+	}
 	/* SDRAM Device DQS-DQ Skew for DQS and associated DQ signals */
 	dimm->tDQSQ = (spd[44] << 8) / 100;
 	/* SDRAM Device Maximum Read Data Hold Skew Factor */
@@ -478,7 +537,8 @@ int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2])
 	/* PLL Relock Time in us */
 	dimm->tPLL = spd[46] << 8;
 	/* Refresh rate in us */
-	dimm->tRR = spd_decode_tRR_time(spd[12]);
+	if (spd_decode_tRR_time(&dimm->tRR, spd[12]) != CB_SUCCESS)
+		ret = SPD_STATUS_INVALID_FIELD;
 
 	/* Number of PLLs on DIMM */
 	if (dimm->rev >= 0x11)