nb/intel/sandybridge/romstage: Read fuse bits for max MEM Clk
Instead of hardcoding the maximum supported DDR frequency to
800Mhz (DDR3-1600), read the fuse bits that encode this information.
Test system:
* Intel IvyBridge
* Gigabyte GA-B75M-D3H
Change-Id: I515a2695a490f16aeb946bfaf3a1e860c607cba9
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/13487
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/northbridge/intel/sandybridge/raminit.c b/src/northbridge/intel/sandybridge/raminit.c
index 65282d2..c154b23 100644
--- a/src/northbridge/intel/sandybridge/raminit.c
+++ b/src/northbridge/intel/sandybridge/raminit.c
@@ -4089,26 +4089,61 @@
static unsigned int get_mem_min_tck(void)
{
+ u32 reg32;
+ u8 rev;
const struct device *dev;
- const struct northbridge_intel_sandybridge_config *cfg;
+ const struct northbridge_intel_sandybridge_config *cfg = NULL;
dev = dev_find_slot(0, HOST_BRIDGE);
- if (!(dev && dev->chip_info))
- return DEFAULT_TCK;
-
- cfg = dev->chip_info;
+ if (dev)
+ cfg = dev->chip_info;
/* If this is zero, it just means devicetree.cb didn't set it */
- if (cfg->max_mem_clock_mhz == 0)
- return DEFAULT_TCK;
+ if (!cfg || cfg->max_mem_clock_mhz == 0) {
+ rev = pci_read_config8(PCI_DEV(0, 0, 0), PCI_DEVICE_ID);
- 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;
- return TCK_400MHZ;
+ if ((rev & BASE_REV_MASK) == BASE_REV_SNB) {
+ /* read Capabilities A Register DMFC bits */
+ reg32 = pci_read_config32(PCI_DEV(0, 0, 0), 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(PCI_DEV(0, 0, 0), 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;
+ } 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;
+ }
}
void perform_raminit(int s3resume)