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/env/flash.c b/env/flash.c
index dcf3cd2..cf068d1 100644
--- a/env/flash.c
+++ b/env/flash.c
@@ -20,10 +20,12 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-#if defined(CONFIG_CMD_SAVEENV) && defined(CONFIG_CMD_FLASH)
-#define CMD_SAVEENV
-#elif defined(CONFIG_ENV_ADDR_REDUND)
-#error CONFIG_ENV_ADDR_REDUND must have CONFIG_CMD_SAVEENV & CONFIG_CMD_FLASH
+#ifndef CONFIG_SPL_BUILD
+# if defined(CONFIG_CMD_SAVEENV) && defined(CONFIG_CMD_FLASH)
+#  define CMD_SAVEENV
+# elif defined(CONFIG_ENV_ADDR_REDUND)
+#  error CONFIG_ENV_ADDR_REDUND must have CONFIG_CMD_SAVEENV & CONFIG_CMD_FLASH
+# endif
 #endif
 
 #if defined(CONFIG_ENV_SIZE_REDUND) &&	\
@@ -31,6 +33,18 @@
 #error CONFIG_ENV_SIZE_REDUND should not be less then CONFIG_ENV_SIZE
 #endif
 
+/* TODO(sjg@chromium.org): Figure out all these special cases */
+#if (!defined(CONFIG_MICROBLAZE) && !defined(CONFIG_ARCH_ZYNQ) && \
+	!defined(CONFIG_TARGET_MCCMON6) && !defined(CONFIG_TARGET_X600) && \
+	!defined(CONFIG_TARGET_EDMINIV2)) || \
+	!defined(CONFIG_SPL_BUILD)
+#define LOADENV
+#endif
+
+#if !defined(CONFIG_TARGET_X600) || !defined(CONFIG_SPL_BUILD)
+#define INITENV
+#endif
+
 char *env_name_spec = "Flash";
 
 #ifdef ENV_IS_EMBEDDED
@@ -58,6 +72,7 @@
 
 
 #ifdef CONFIG_ENV_ADDR_REDUND
+#ifdef INITENV
 int env_init(void)
 {
 	int crc1_ok = 0, crc2_ok = 0;
@@ -101,6 +116,7 @@
 
 	return 0;
 }
+#endif
 
 #ifdef CMD_SAVEENV
 int saveenv(void)
@@ -207,6 +223,7 @@
 
 #else /* ! CONFIG_ENV_ADDR_REDUND */
 
+#ifdef INITENV
 int env_init(void)
 {
 	if (crc32(0, env_ptr->data, ENV_SIZE) == env_ptr->crc) {
@@ -219,6 +236,7 @@
 	gd->env_valid	= 0;
 	return 0;
 }
+#endif
 
 #ifdef CMD_SAVEENV
 int saveenv(void)
@@ -336,3 +354,16 @@
 
 	env_import((char *)flash_addr, 1);
 }
+
+U_BOOT_ENV_LOCATION(flash) = {
+	.location	= ENVL_FLASH,
+#ifdef LOADENV
+	.load		= env_relocate_spec,
+#endif
+#ifdef CMD_SAVEENV
+	.save		= env_save_ptr(saveenv),
+#endif
+#ifdef INITENV
+	.init		= env_init,
+#endif
+};