nb/intel/sandybridge: Refactor get_mem_min_tck

It is not necessary to pass its value around various function calls.
Move it closer to where it is actually used, so as to make it static.
Also, use config_of_soc and flip the branches of the first conditional.

Tested on Asus P8Z77-V LX2, still boots.

Change-Id: I5c49c943c87218d4d40d3168bd8b7b900b0ec2e9
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39851
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/src/northbridge/intel/sandybridge/raminit_native.c b/src/northbridge/intel/sandybridge/raminit_native.c
index 99c1a4c4ff..832391f72e 100644
--- a/src/northbridge/intel/sandybridge/raminit_native.c
+++ b/src/northbridge/intel/sandybridge/raminit_native.c
@@ -5,7 +5,10 @@
 #include <console/console.h>
 #include <console/usb.h>
 #include <delay.h>
+#include <device/device.h>
+#include <device/pci_def.h>
 #include <device/pci_ops.h>
+#include <northbridge/intel/sandybridge/chip.h>
 #include "raminit_native.h"
 #include "raminit_common.h"
 #include "raminit_tables.h"
@@ -174,6 +177,78 @@ static void normalize_tclk(ramctr_timing *ctrl, bool ref_100mhz_support)
 	}
 }
 
+#define DEFAULT_TCK	TCK_800MHZ
+
+static unsigned int get_mem_min_tck(void)
+{
+	u32 reg32;
+	u8 rev;
+	const struct northbridge_intel_sandybridge_config *cfg = NULL;
+
+	/* Actually, config of MCH or Host Bridge */
+	cfg = config_of_soc();
+
+	/* If non-zero, it was set in the devicetree */
+	if (cfg->max_mem_clock_mhz) {
+
+		if (cfg->max_mem_clock_mhz >= 1066)
+			return TCK_1066MHZ;
+
+		else if (cfg->max_mem_clock_mhz >= 933)
+			return TCK_933MHZ;
+
+		else if (cfg->max_mem_clock_mhz >= 800)
+			return TCK_800MHZ;
+
+		else if (cfg->max_mem_clock_mhz >= 666)
+			return TCK_666MHZ;
+
+		else if (cfg->max_mem_clock_mhz >= 533)
+			return TCK_533MHZ;
+
+		else
+			return TCK_400MHZ;
+	}
+
+	if (CONFIG(NATIVE_RAMINIT_IGNORE_MAX_MEM_FUSES))
+		return TCK_1333MHZ;
+
+	rev = pci_read_config8(HOST_BRIDGE, PCI_DEVICE_ID);
+
+	if ((rev & BASE_REV_MASK) == BASE_REV_SNB) {
+		/* Read Capabilities A Register DMFC bits */
+		reg32 = pci_read_config32(HOST_BRIDGE, CAPID0_A);
+		reg32 &= 0x7;
+
+		switch (reg32) {
+		case 7: return TCK_533MHZ;
+		case 6: return TCK_666MHZ;
+		case 5: return TCK_800MHZ;
+		/* Reserved */
+		default:
+			break;
+		}
+	} else {
+		/* Read Capabilities B Register DMFC bits */
+		reg32 = pci_read_config32(HOST_BRIDGE, CAPID0_B);
+		reg32 = (reg32 >> 4) & 0x7;
+
+		switch (reg32) {
+		case 7: return TCK_533MHZ;
+		case 6: return TCK_666MHZ;
+		case 5: return TCK_800MHZ;
+		case 4: return TCK_933MHZ;
+		case 3: return TCK_1066MHZ;
+		case 2: return TCK_1200MHZ;
+		case 1: return TCK_1333MHZ;
+		/* Reserved */
+		default:
+			break;
+		}
+	}
+	return DEFAULT_TCK;
+}
+
 static void find_cas_tck(ramctr_timing *ctrl)
 {
 	u8 val;
@@ -188,6 +263,8 @@ static void find_cas_tck(ramctr_timing *ctrl)
 
 	printk(BIOS_DEBUG, "PLL_REF100_CFG value: 0x%x\n", ref_100mhz_support);
 
+	ctrl->tCK = get_mem_min_tck();
+
 	/* Find CAS latency */
 	while (1) {
 		/*