Patch set updated for coreboot: device/dram/ddr2: Add common function to select common CAS en freq

[Arthur Heymans]

Arthur Heymans ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/18320

-gerrit

commit 04c1d6b8e1cac7982ef1fdf1596ab88571ce99f3
Author: Arthur Heymans 
Date:   Fri Feb 10 12:08:16 2017 +0100

device/dram/ddr2: Add common function to select common CAS en freq

This function finds highest common CAS and select tCLK based on
    the dimm with highest minumum tCLK at that selected CAS.

Change-Id: I3ab39d38a243edddfde8f70ebd23f79ff774e90e
    Signed-off-by: Arthur Heymans 
---
 src/device/dram/ddr2.c         | 57 ++++++++++++++++++++++++++++++++++++++++++
 src/include/device/dram/ddr2.h |  3 ++-
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/src/device/dram/ddr2.c b/src/device/dram/ddr2.c
index c2bfe0c..1ae788d 100644
--- a/src/device/dram/ddr2.c
+++ b/src/device/dram/ddr2.c
@@ -2,6 +2,7 @@
  * This file is part of the coreboot project.
  *
  * Copyright (C) 2017 Patrick Rudolph 
+ * Copyright (C) 2017 Arthur Heymans 
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -635,3 +636,59 @@ void dram_print_spd_ddr2(const dimm_attr *dimm)
    print_us("  tPLL              : ", dimm->tPLL);
    print_us("  tRR               : ", dimm->tRR);
 }
+
+u32 get_common_freq_cas(u8 cas_mask, const dimm_attr *dimm, int num_dimms,
+			u8 *selected_cas)
+{
+	int i, high_common_cas;
+	u32 tCLK = 0;
+
+	for (i = 0; i < num_dimms; i++) {
+		if (dimm[i].dimm_type == SPD_DIMM_TYPE_UNDEFINED)
+			continue;
+		cas_mask &= dimm[i].cas_supported;
+	}
+
+	if (!cas_mask) {
+		printk(BIOS_DEBUG, "No common supported CAS\n");
+		return 0;
+	}
+
+	high_common_cas = spd_get_msbs(cas_mask);
+	for (i = 0; i < num_dimms; i++) {
+		if (dimm[i].dimm_type == SPD_DIMM_TYPE_UNDEFINED)
+			continue;
+		if (dimm[i].cycle_time[high_common_cas] == 0)
+			printk(BIOS_DEBUG, "No minimum tCLK defined for dimm %d at CAS %d\n",
+				i, high_common_cas);
+		if (tCLK < dimm[i].cycle_time[high_common_cas])
+			tCLK = dimm[i].cycle_time[high_common_cas];
+	}
+
+	if (tCLK == 0) {
+		printk(BIOS_DEBUG, "No valid minimum tCLK found\n");
+		return 0;
+	}
+
+	if (tCLK <= TCK_800MHZ) {
+		tCLK = TCK_800MHZ;
+	} else if (tCLK <= TCK_666MHZ) {
+		tCLK = TCK_666MHZ;
+	} else if (tCLK <= TCK_533MHZ) {
+		tCLK = TCK_533MHZ;
+	} else if (tCLK <= TCK_400MHZ) {
+		tCLK = TCK_400MHZ;
+	} else if (tCLK <= TCK_333MHZ) {
+		tCLK = TCK_333MHZ;
+	} else if (tCLK <= TCK_266MHZ) {
+		tCLK = TCK_266MHZ;
+	} else if (tCLK <= TCK_200MHZ) {
+		tCLK = TCK_200MHZ;
+	} else {
+		prink(BIOS_DEBUG, "Too slow common tCLK found\n");
+		return 0;
+	}
+
+	*selected_cas = high_common_cas;
+	return tCLK;
+}
diff --git a/src/include/device/dram/ddr2.h b/src/include/device/dram/ddr2.h
index ae02c40..4c33b1b 100644
--- a/src/include/device/dram/ddr2.h
+++ b/src/include/device/dram/ddr2.h
@@ -210,6 +210,7 @@ u32 spd_decode_spd_size_ddr2(u8 byte0);
 u32 spd_decode_eeprom_size_ddr2(u8 byte1);
 int spd_decode_ddr2(dimm_attr *dimm, spd_raw_data spd);
 void dram_print_spd_ddr2(const dimm_attr *dimm);
-
+u32 get_common_freq_cas(u8 cas_mask, const dimm_attr *dimm, int num_dimms,
+			 u8 *selected_cas);

#endif /* DEVICE_DRAM_DDR2L_H */