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 c7f1579981c65dc7effa63a19f7a569a46119bca
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         | 54 ++++++++++++++++++++++++++++++++++++++++++
 src/include/device/dram/ddr2.h | 15 +++++++++++-
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/src/device/dram/ddr2.c b/src/device/dram/ddr2.c
index 4224d6e..6621c49 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
@@ -597,3 +598,56 @@ 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;
+	}
+
+	*selected_cas = high_common_cas;
+	return tCLK;
+}
diff --git a/src/include/device/dram/ddr2.h b/src/include/device/dram/ddr2.h
index a7b3ad9..b6bbcb7 100644
--- a/src/include/device/dram/ddr2.h
+++ b/src/include/device/dram/ddr2.h
@@ -46,6 +46,18 @@
 #define TCK_333MHZ      768
 #define TCK_266MHZ      960
 #define TCK_200MHZ      1280
+
+enum dram_freq {
+	DDR2_200MHZ,
+	DDR2_266MHZ,
+	DDR2_333MHZ,
+	DDR2_400MHZ,
+	DDR2_533MHZ,
+	DDR2_666MHZ,
+	DDR2_700MHZ,
+	DDR2_800MHZ,
+};
+
 /** @} */

/**
@@ -200,6 +212,7 @@ 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 */