[PATCH v2 1/2] env: add SAVEENV as an alias of the CMD_SAVEENV symbol

[Rasmus Villemoes]

Currently, quite a few storage drivers currently do not honour
SPL_SAVEENV. That is, whether or not one enables CONFIG_SPL_SAVEENV,
the backend drivers do not provide the .save method. Witness

env/fat.c:#ifdef CONFIG_SPL_BUILD
...
env/fat.c-#else
env/fat.c-# define LOADENV
env/fat.c:# if defined(CONFIG_CMD_SAVEENV)
env/fat.c:#  define CMD_SAVEENV
env/fat.c-# endif
env/fat.c-#endif
env/fat.c-
env/fat.c:#ifdef CMD_SAVEENV
env/fat.c-static int env_fat_save(void)

env/flash.c:#ifndef CONFIG_SPL_BUILD
env/flash.c:# if defined(CONFIG_CMD_SAVEENV) && defined(CONFIG_CMD_FLASH)
env/flash.c:#  define CMD_SAVEENV
...
env/flash.c:#ifdef CMD_SAVEENV
env/flash.c-static int env_flash_save(void)

env/mmc.c:#if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_SPL_BUILD)
env/mmc.c-static inline int write_env(struct mmc *mmc, unsigned long size,

env/nand.c:#if defined(CONFIG_CMD_SAVEENV) && defined(CONFIG_CMD_NAND) && \
env/nand.c:             !defined(CONFIG_SPL_BUILD)
env/nand.c:#define CMD_SAVEENV
...
env/nand.c:#ifdef CMD_SAVEENV
env/nand.c-/*
env/nand.c- * The legacy NAND code saved the environment in the first NAND device i.e.,
env/nand.c- * nand_dev_desc + 0. This is also the behaviour using the new NAND code.
env/nand.c- */
env/nand.c-static int writeenv(size_t offset, u_char *buf)

env/sf.c:#ifndef CONFIG_SPL_BUILD
env/sf.c:#define CMD_SAVEENV
env/sf.c-#define INITENV
env/sf.c-#endif
...
env/sf.c:#ifdef CMD_SAVEENV
env/sf.c-static int env_sf_save(void)

In all these cases, the mere presence of CONFIG_SPL_BUILD means the
save method does not get built.

Now, it is currently a bit awkward to write a proper test for whether
saving the environment is enabled in the current context; something
like

#if (!defined(CONFIG_SPL_BUILD) && defined(CONFIG_CMD_SAVEENV)) || \
    (defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_SAVEENV))

But we already have a rather elegant mechanism that implicitly does
the CONFIG_SPL_BUILD tests, namely CONFIG_IS_ENABLED(). Using that
requires that the controlling config symbols follow a strict pattern:
FOO for U-Boot proper, SPL_FOO for SPL.

This patch introduces CONFIG_SAVEENV as an alias for
CONFIG_CMD_SAVEENV. That way, the above can simply be written

#if CONFIG_IS_ENABLED(SAVEENV)

and moreover, CONFIG_IS_ENABLED(SAVEENV) can also be used in C code,
avoiding ifdeffery and providing more compile testing.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>
---
v2: Expand commit message, explain why one needs a new config symbol
in order to use CONFIG_IS_ENABLED, and demonstrate how many of the
storage drivers don't compile their .save method when
CONFIG_SPL_BUILD. The patch itself is the same.

 env/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/env/Kconfig b/env/Kconfig
index 0d6f559b39..969308fe6c 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -3,6 +3,9 @@ menu "Environment"
 config ENV_SUPPORT
 	def_bool y
 
+config SAVEENV
+	def_bool y if CMD_SAVEENV
+
 config ENV_IS_NOWHERE
 	bool "Environment is not stored"
 	default y if !ENV_IS_IN_EEPROM && !ENV_IS_IN_EXT4 && \
-- 
2.23.0