diff options
author | Reka Norman <rekanorman@google.com> | 2021-11-08 11:18:42 +1100 |
---|---|---|
committer | Tim Wawrzynczak <twawrzynczak@chromium.org> | 2021-11-09 23:45:26 +0000 |
commit | e6a1ebe55ba6bbcd791e40a934bd3e65fad31cb9 (patch) | |
tree | 51f73817a63746dbf4b7423a58a1b259e6786d01 /util/spd_tools | |
parent | b455dd3486a7b2e0b8d98c907cb9389c8283faff (diff) |
util/spd_tools: Document adding support for a new memory technology
Add documentation describing how to add support for a new memory
technology to spd_tools:
- Add a section to the README.
- Document the memTech interface in spd_gen.go.
BUG=b:191776301
TEST=None
Signed-off-by: Reka Norman <rekanorman@google.com>
Change-Id: Ie710c1c686ddf5288db35cf43e5f1ac9b1974305
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59005
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Diffstat (limited to 'util/spd_tools')
-rw-r--r-- | util/spd_tools/README.md | 45 | ||||
-rw-r--r-- | util/spd_tools/src/spd_gen/spd_gen.go | 27 |
2 files changed, 72 insertions, 0 deletions
diff --git a/util/spd_tools/README.md b/util/spd_tools/README.md index a422017581..3a1342c85a 100644 --- a/util/spd_tools/README.md +++ b/util/spd_tools/README.md @@ -590,3 +590,48 @@ util/spd_tools/bin/part_id_gen \ `dram_id.generated.txt` with the new part. * Upload the changes to `Makefile.inc` and `dram_id.generated.txt` for review. + +## How to add support for a new memory technology + +### 1. Gather the SPD requirements + +To generate SPDs for the new memory technology, information is needed about the +list of bytes in the SPD and how the value of each byte should be determined. +This information usually comes from a combination of: + +* The JEDEC spec for the memory technology, e.g. JESD209-5B for LPDDR5. +* The JEDEC SPD spec for the memory technology, e.g. SPD4.1.2.M-2 for LPDDR3/4 + (also used for LP4x and LP5). +* Platform-specific requirements. SoC vendors often don't follow the JEDEC + specs exactly. E.g. the memory training code may expect certain SPD bytes to + encode a different value to what is stated in the spec. So for each SoC + platform using the new memory technology, any platform-specific requirements + need to be gathered. + +### 2. Implement support in spd_tools + +Support for the new memory technology needs to be added to both the `spd_gen` +and `part_id_gen` tools. + +#### `spd_gen` + +Adding support to `spd_gen` requires implementing the logic to generate SPDs for +the new memory technology. The changes required are: + +* Add the new memory technology to the `memTechMap` in `spd_gen/spd_gen.go`. +* Add a new file `spd_gen/<mem_tech>.go`. This file will contain all the logic + for generating SPDs for the new memory technology. It needs to implement the + `memTech` interface defined in `spd_gen/spd_gen.go`. The interface functions + are documented inline. Examples of how the interface is implemented for + existing memory technologies can be found in the `spd_gen/` directory, e.g. + `lp4x.go`, `ddr4.go`, `lp5.go`. While not strictly necessary, it is + recommended to follow the overall structure of these existing files when + adding a new memory technology. + +#### `part_id_gen` + +The `part_id_gen` tool is memory technology-agnostic, so the only change +required is: + +* Add the new memory technology to the `supportedMemTechs` list in + `part_id_gen/part_id_gen.go`. diff --git a/util/spd_tools/src/spd_gen/spd_gen.go b/util/spd_tools/src/spd_gen/spd_gen.go index fa6549262d..6cc910272f 100644 --- a/util/spd_tools/src/spd_gen/spd_gen.go +++ b/util/spd_tools/src/spd_gen/spd_gen.go @@ -28,10 +28,37 @@ type memPart struct { } type memTech interface { + /* + * Returns the set -> platform mapping for the memory technology. Platforms with the + * same SPD requirements should be grouped together into a single set. + */ getSetMap() map[int][]int + + /* + * Takes the name and attributes of a part, as read from the memory_parts JSON file. + * Validates the attributes, returning an error if any attribute has an invalid value. + * Stores the name and attributes internally to be used later. + */ addNewPart(string, interface{}) error + + /* + * Takes the name of a part and a set number. + * Retrieves the part's attributes which were stored by addNewPart(). Updates them by + * setting any optional attributes which weren't specified in the JSON file to their + * default values. + * Returns these updated attributes. + */ getSPDAttribs(string, int) (interface{}, error) + + /* + * Returns the size of an SPD file for this memory technology. + */ getSPDLen() int + + /* + * Takes an SPD byte index and the attributes of a part. + * Returns the value which that SPD byte should be set to based on the attributes. + */ getSPDByte(int, interface{}) byte } |