1 files changed, 97 insertions, 0 deletions
diff --git a/util/spd_tools/README.md b/util/spd_tools/README.md
index 5be666bde4f6..a42201758184 100644
--- a/util/spd_tools/README.md
+++ b/util/spd_tools/README.md
@@ -8,6 +8,9 @@ The memory technologies currently supported are:
 *   LPDDR4x - based on the JESD209-4C spec and Intel recommendations
     (docs #616599, #610202, #634730).
 *   DDR4 - based on the JESD79-4C and Jedec 4.1.2.L-5 R29 v103 specs.
+*   LPDDR5 - based on the LPDDR5 spec JESD209-5B, the SPD spec SPD4.1.2.M-2 (the
+    LPDDR3/4 spec is used since JEDEC has not released an SPD spec for LPDDR5),
+    and Intel recommendations in advisory #616599.
 
 There are two tools provided to assist with generating SPDs and Makefiles to
 integrate into the coreboot build. These tools can also be used to allocate DRAM
@@ -292,6 +295,100 @@ string like "9 10 11 12 14".
 }
 ```
 
+### LP5 attributes
+
+#### Mandatory
+
+*   `densityPerDieGb`: Density per die in Gb. Valid values: `4, 6, 8, 12, 16,
+    24, 32` Gb per die.
+
+*   `diesPerPackage`: Number of physical dies in each SDRAM package. Valid
+    values: `2, 4, 8` dies per package.
+
+*   `bitWidthPerChannel`: Width of each physical channel. Valid values: `8, 16`
+    bits.
+
+*   `ranksPerChannel`: Number of ranks per physical channel. Valid values: `1,
+    2`. If the channels across multiple dies share the same DQ/DQS pins but use
+    a separate CS, then ranks is 2 else it is 1.
+
+*   `speedMbps`: Maximum data rate supported by the part in Mbps. Valid values:
+    `5500, 6400` Mbps.
+
+#### Optional
+
+*   `trfcabNs`: Minimum Refresh Recovery Delay Time (tRFCab) for all banks in
+    nanoseconds. As per JESD209-5B, this is dependent on the density per die.
+    Default values used:
+
+    *   4 Gb : 180 ns
+    *   6 Gb : 210 ns
+    *   8 Gb : 210 ns
+    *   12 Gb: 280 ns
+    *   16 Gb: 280 ns
+    *   24 Gb: 380 ns
+    *   32 Gb: 380 ns
+
+*   `trfcpbNs`: Minimum Refresh Recovery Delay Time (tRFCpb) per bank in
+    nanoseconds. As per JESD209-5B, this is dependent on the density per die.
+    Default values used:
+
+    *   4 Gb : 90 ns
+    *   6 Gb : 120 ns
+    *   8 Gb : 120 ns
+    *   12 Gb: 140 ns
+    *   16 Gb: 140 ns
+    *   24 Gb: 190 ns
+    *   32 Gb: 190 ns
+
+*   `trpabMinNs`: Minimum Row Precharge Delay Time (tRPab) for all banks in
+    nanoseconds. As per JESD209-5B, this is max(21ns, 2nCK), which defaults to
+    `21 ns`.
+
+*   `trppbMinNs`: Minimum Row Precharge Delay Time (tRPpb) per bank in
+    nanoseconds. As per JESD209-5B, this is max(18ns, 2nCK) which defaults to
+    `18 ns`.
+
+*   `tckMinPs`: SDRAM minimum cycle time (tCKmin) value in picoseconds. LPDDR5
+    has two clocks: the command/addrees clock (CK) and the data clock (WCK).
+    They are related by the WCK:CK ratio, which can be either 4:1 or 2:1. For
+    LPDDR5, tCKmin is the CK period, which can be calculated from the
+    `speedMbps` attribute and the WCK:CK ratio as follows: `tCKmin = 1 /
+    (speedMbps / 2 / WCK:CK)`. The default values used are for a 4:1 WCK:CK
+    ratio:
+
+    *   6400 Mbps: 1250 ps
+    *   5500 Mbps: 1455 ps
+
+*   `taaMinPs`: Minimum CAS Latency Time(tAAmin) in picoseconds. This value
+    defaults to nck * tCKmin, where nck is maximum CAS latency, and is
+    determined from the `speedMbps` attribute as per JESD209-5B:
+
+    *   6400 Mbps: 17
+    *   5500 Mbps: 15
+
+*   `trcdMinNs`: Minimum RAS# to CAS# Delay Time (tRCDmin) in nanoseconds. As
+    per JESD209-5B, this is max(18ns, 2nCK) which defaults to `18 ns`.
+
+#### Example `memory_parts.json`
+
+```
+{
+    "parts": [
+        {
+            "name": "MT62F1G32D4DR-031 WT:B",
+            "attribs": {
+                "densityPerDieGb": 8,
+                "diesPerPackage": 4,
+                "bitWidthPerChannel": 16,
+                "ranksPerChannel": 2,
+                "speedMbps": 6400
+            }
+        },
+    ]
+}
+```
+
 ### Output
 
 The `spd_gen` tool generates the directory structure shown below. The inputs to