nvmem: add driver handling U-Boot environment variables

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U-Boot stores its setup as environment variables. It's a list of
key-value pairs stored on flash device with a custom header.

This commit adds an NVMEM driver that:
1. Provides NVMEM access to environment vars binary data
2. Extracts variables as NVMEM cells

Current Linux's NVMEM sysfs API allows reading whole NVMEM data block.
It can be used by user-space tools for reading U-Boot env vars block
without the hassle of finding its location. Parsing will still need to
be re-done there.

Kernel-parsed NVMEM cells can be read however by Linux drivers. This may
be useful for Ethernet drivers for reading device MAC address which is
often stored as U-Boot env variable.

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220916122100.170016-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Rafał Miłecki 2022-09-16 13:20:48 +01:00 • committed by Greg Kroah-Hartman

parent 42992cf187

commit d5542923f2

4 changed files with 234 additions and 0 deletions

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1

MAINTAINERS

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13

drivers/nvmem/Kconfig

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2

drivers/nvmem/Makefile

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218

drivers/nvmem/u-boot-env.c

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