nb/intel/*: Fill in SMBIOS type 16 on SNB/HSW

Fill in the maximum DRAM capacity and slot count read from CAPID0_A
registers on Sandy Bridge and Haswell.

While the register isn't part of the Core Series datasheet, it can be
found in the corresponding "Intel Open Source Graphics Programmer's
Reference" datasheets.

Note that the values for DDRSZ (maximum allowed memory size per channel)
need to be halved when only one DIMM per channel is supported. On mobile
platforms, all but quad-core processors are subject to this restriction.

Tested on Lenovo X230:
On Linux, verify that `dmidecode -t 16` reports the actual maximum
capacity (16 GiB) instead of the currently-installed capacity (4 GiB) or
the max capacity assuming two DIMMs per channel is possible (32 GiB).

Change-Id: I6e2346de1ffe52e8685276acbdbf25755f4cc162
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43971
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Christian Walter <christian.walter@9elements.com>

2 files changed, 60 insertions, 3 deletions

diff --git a/src/northbridge/intel/sandybridge/hostbridge_regs.h b/src/northbridge/intel/sandybridge/hostbridge_regs.h
index 00d37d4a6d..2d2fcff3b1 100644
--- a/src/northbridge/intel/sandybridge/hostbridge_regs.h
+++ b/src/northbridge/intel/sandybridge/hostbridge_regs.h
@@ -49,6 +49,11 @@
 #define TOLUD		0xbc	/* Top of Low Used Memory */
 
 #define CAPID0_A	0xe4	/* Capabilities Register A */
+#define  CAPID_ECCDIS	(1 << 25)
+#define  CAPID_DDPCD	(1 << 14)
+#define  CAPID_PDCD	(1 << 12)
+#define  CAPID_DDRSZ(x)	(((x) >> 19) & 0x3)
+
 #define CAPID0_B	0xe8	/* Capabilities Register B */
 
 #define SKPAD		0xdc	/* Scratchpad Data */
diff --git a/src/northbridge/intel/sandybridge/raminit.c b/src/northbridge/intel/sandybridge/raminit.c
index 422067b5d2..2728037ac9 100644
--- a/src/northbridge/intel/sandybridge/raminit.c
+++ b/src/northbridge/intel/sandybridge/raminit.c
@@ -54,8 +54,47 @@ static void disable_channel(ramctr_timing *ctrl, int channel)
 	memset(&ctrl->info.dimm[channel][0], 0, sizeof(ctrl->info.dimm[0]));
 }
 
-/* Fill cbmem with information for SMBIOS type 17 */
-static void fill_smbios17(ramctr_timing *ctrl)
+static bool nb_supports_ecc(const uint32_t capid0_a)
+{
+	return !(capid0_a & CAPID_ECCDIS);
+}
+
+static uint16_t nb_slots_per_channel(const uint32_t capid0_a)
+{
+	return !(capid0_a & CAPID_DDPCD) + 1;
+}
+
+static uint16_t nb_number_of_channels(const uint32_t capid0_a)
+{
+	return !(capid0_a & CAPID_PDCD) + 1;
+}
+
+static uint32_t nb_max_chan_capacity_mib(const uint32_t capid0_a)
+{
+	uint32_t ddrsz;
+
+	/* Values from documentation, which assume two DIMMs per channel */
+	switch (CAPID_DDRSZ(capid0_a)) {
+	case 1:
+		ddrsz = 8192;
+		break;
+	case 2:
+		ddrsz = 2048;
+		break;
+	case 3:
+		ddrsz = 512;
+		break;
+	default:
+		ddrsz = 16384;
+		break;
+	}
+
+	/* Account for the maximum number of DIMMs per channel */
+	return (ddrsz / 2) * nb_slots_per_channel(capid0_a);
+}
+
+/* Fill cbmem with information for SMBIOS type 16 and type 17 */
+static void setup_sdram_meminfo(ramctr_timing *ctrl)
 {
 	int channel, slot;
 	const u16 ddr_freq = (1000 << 8) / ctrl->tCK;
@@ -66,6 +105,19 @@ static void fill_smbios17(ramctr_timing *ctrl)
 		if (ret != CB_SUCCESS)
 			printk(BIOS_ERR, "RAMINIT: Failed to add SMBIOS17\n");
 	}
+
+	/* The 'spd_add_smbios17' function allocates this CBMEM area */
+	struct memory_info *m = cbmem_find(CBMEM_ID_MEMINFO);
+	if (m == NULL)
+		return;
+
+	const uint32_t capid0_a = pci_read_config32(HOST_BRIDGE, CAPID0_A);
+
+	const uint16_t channels = nb_number_of_channels(capid0_a);
+
+	m->ecc_capable = nb_supports_ecc(capid0_a);
+	m->max_capacity_mib = channels * nb_max_chan_capacity_mib(capid0_a);
+	m->number_of_devices = channels * nb_slots_per_channel(capid0_a);
 }
 
 /* Return CRC16 match for all SPDs */
@@ -386,7 +438,7 @@ static void init_dram_ddr3(int s3resume, const u32 cpuid)
 	}
 
 	if (!s3resume)
-		fill_smbios17(&ctrl);
+		setup_sdram_meminfo(&ctrl);
 }
 
 void perform_raminit(int s3resume)