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| author | Michael Walle <michael@walle.cc> | 2023-04-04 18:21:21 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-04-05 19:41:11 +0200 |
| commit | 266570f496b90dea8fda893c2cf7c28d63ae2bd9 (patch) | |
| tree | 8f249c056530d430fec83e63a850bdbdb483d0bb /Documentation/driver-api/nvmem.rst | |
| parent | 2f555f58f5ce33b201235e104823662d5573c4a5 (diff) | |
nvmem: core: introduce NVMEM layouts
NVMEM layouts are used to generate NVMEM cells during runtime. Think of
an EEPROM with a well-defined conent. For now, the content can be
described by a device tree or a board file. But this only works if the
offsets and lengths are static and don't change. One could also argue
that putting the layout of the EEPROM in the device tree is the wrong
place. Instead, the device tree should just have a specific compatible
string.
Right now there are two use cases:
(1) The NVMEM cell needs special processing. E.g. if it only specifies
a base MAC address offset and you need to add an offset, or it
needs to parse a MAC from ASCII format or some proprietary format.
(Post processing of cells is added in a later commit).
(2) u-boot environment parsing. The cells don't have a particular
offset but it needs parsing the content to determine the offsets
and length.
Co-developed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230404172148.82422-14-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/driver-api/nvmem.rst')
| -rw-r--r-- | Documentation/driver-api/nvmem.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/driver-api/nvmem.rst b/Documentation/driver-api/nvmem.rst index e3366322d46c..de221e91c8e3 100644 --- a/Documentation/driver-api/nvmem.rst +++ b/Documentation/driver-api/nvmem.rst @@ -185,3 +185,18 @@ ex:: ===================== See Documentation/devicetree/bindings/nvmem/nvmem.txt + +8. NVMEM layouts +================ + +NVMEM layouts are yet another mechanism to create cells. With the device +tree binding it is possible to specify simple cells by using an offset +and a length. Sometimes, the cells doesn't have a static offset, but +the content is still well defined, e.g. tag-length-values. In this case, +the NVMEM device content has to be first parsed and the cells need to +be added accordingly. Layouts let you read the content of the NVMEM device +and let you add cells dynamically. + +Another use case for layouts is the post processing of cells. With layouts, +it is possible to associate a custom post processing hook to a cell. It +even possible to add this hook to cells not created by the layout itself. |