env: Create a location driver for each location
Set up a location driver for each supported environment location. At
present this just points to the global functions and is not used. A
later patch will switch this over to use private functions in each driver.
There are several special cases here in various drivers to handle
peculiarities of certain boards:
1. Some boards define CONFIG_ENV_IS_IN_FAT and CONFIG_SPL_ENV_SUPPORT but
do not actually load the environment in SPL. The env load code was
optimised out before but with the driver, it is not. Therefore a special
case is added to env/fat.c. The correct fix (depending on board testing
might be to disable CONFIG_SPL_ENV_SUPPORT.
2. A similar situations happens with CONFIG_ENV_IS_IN_FLASH. Some boards
do not actually load the environment in SPL, so to reduce code size we
need to drop that code. A similar fix may be possible with these boards,
or it may be possible to adjust the environment CONFIG settings.
Added to the above is that the CONFIG_SPL_ENV_SUPPORT option does not
apply when the environment is in flash.
Obviously the above has been discovered through painful and time-consuming
trial and error. Hopefully board maintainers can take a look and figure
out what is actually needed.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/environment.h b/include/environment.h
index ad2331c..ff3f542 100644
--- a/include/environment.h
+++ b/include/environment.h
@@ -204,6 +204,76 @@
ENV_REDUND, /* Redundant environment is valid */
};
+enum env_location {
+ ENVL_DATAFLASH,
+ ENVL_EEPROM,
+ ENVL_EXT4,
+ ENVL_FAT,
+ ENVL_FLASH,
+ ENVL_MMC,
+ ENVL_NAND,
+ ENVL_NVRAM,
+ ENVL_ONENAND,
+ ENVL_REMOTE,
+ ENVL_SPI_FLASH,
+ ENVL_UBI,
+ ENVL_NOWHERE,
+
+ ENVL_COUNT,
+ ENVL_UNKNOWN,
+};
+
+struct env_driver {
+ enum env_location location;
+
+ /**
+ * get_char() - Read a character from the environment
+ *
+ * This method is optional. If not provided, a default implementation
+ * will read from gd->env_addr.
+ *
+ * @index: Index of character to read (0=first)
+ * @return character read
+ */
+ unsigned char (*get_char)(int index);
+
+ /**
+ * load() - Load the environment from storage
+ *
+ * This method is optional. If not provided, no environment will be
+ * loaded.
+ */
+ void (*load)(void);
+
+ /**
+ * save() - Save the environment to storage
+ *
+ * This method is required for 'saveenv' to work.
+ *
+ * @return 0 if OK, -ve on error
+ */
+ int (*save)(void);
+
+ /**
+ * init() - Set up the initial pre-relocation environment
+ *
+ * This method is optional.
+ *
+ * @return 0 if OK, -ve on error
+ */
+ int (*init)(void);
+};
+
+/* Declare a new environment location driver */
+#define U_BOOT_ENV_LOCATION(__name) \
+ ll_entry_declare(struct env_driver, __name, env_driver)
+
+#ifdef CONFIG_CMD_SAVEENV
+#define env_save_ptr(x) x
+#else
+#define env_save_ptr(x) NULL
+#endif
+
extern struct hsearch_data env_htab;
/* Function that returns a character from the environment */