spl: saveenv: adding saveenv support in SPL

By default saveenv option is not supported for SPL. This patch
enable the support for save environment variable for SPL build.

Enable save environment support in SPL after setenv. By default
the saveenv option is not provided in SPL, but some boards need
this support in 'Falcon' boot, where SPL need to boot from
different images based on environment variable set by OS. For
example OS may set "reboot_image" environment variable to
"recovery" inorder to boot recovery image by SPL. The SPL read
"reboot_image" and act accordingly and change the reboot_image
to default mode using setenv and save the environemnt.

Signed-off-by: Ravi Babu <ravibabu@ti.com>
Reviewed-by: Simon Glass <sig@chromium.org>

change in v1:
	- dropped SUPPORT, use CONFIG_SPL_SAVEENV
	- updates the comments in mmc_private.h

common/spl/Kconfig

@@ -172,6 +172,19 @@ config SPL_ENV_SUPPORT
 	  starting U-Boot first. Enabling this option will make getenv()
 	  and setenv() available in SPL.
 
+config SPL_SAVEENV
+	bool "Support save environment"
+	depends on SPL && SPL_ENV_SUPPORT
+	help
+	  Enable save environment support in SPL after setenv. By default
+	  the saveenv option is not provided in SPL, but some boards need
+	  this support in 'Falcon' boot, where SPL need to boot from
+	  different images based on environment variable set by OS. For
+	  example OS may set "reboot_image" environment variable to
+	  "recovery" inorder to boot recovery image by SPL. The SPL read
+	  "reboot_image" and act accordingly and change the reboot_image
+	  to default mode using setenv and save the environemnt.
+
 config SPL_ETH_SUPPORT
 	bool "Support Ethernet"
 	depends on SPL_ENV_SUPPORT

drivers/mmc/Makefile

@@ -60,6 +60,7 @@ obj-$(CONFIG_ROCKCHIP_SDHCI) += rockchip_sdhci.o
 
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_SPL_MMC_BOOT) += fsl_esdhc_spl.o
+obj-$(CONFIG_SPL_SAVEENV) += mmc_write.o
 else
 obj-$(CONFIG_GENERIC_MMC) += mmc_write.o
 endif

drivers/mmc/mmc_private.h

@@ -28,8 +28,7 @@ ulong mmc_bread(struct blk_desc *block_dev, lbaint_t start, lbaint_t blkcnt,
 		void *dst);
 #endif
 
-#ifndef CONFIG_SPL_BUILD
-
+#if !(defined(CONFIG_SPL_BUILD) && !defined(CONFIG_SPL_SAVEENV))
 unsigned long mmc_berase(struct blk_desc *block_dev, lbaint_t start,
 			 lbaint_t blkcnt);
 
@@ -41,9 +40,9 @@ ulong mmc_bwrite(struct blk_desc *block_dev, lbaint_t start, lbaint_t blkcnt,
 		 const void *src);
 #endif
 
-#else /* CONFIG_SPL_BUILD */
+#else /* CONFIG_SPL_BUILD and CONFIG_SPL_SAVEENV is not defined */
 
-/* SPL will never write or erase, declare dummies to reduce code size. */
+/* declare dummies to reduce code size. */
 
 #ifdef CONFIG_BLK
 static inline unsigned long mmc_berase(struct udevice *dev,

lib/Makefile

@@ -47,6 +47,7 @@ obj-$(CONFIG_$(SPL_)RSA) += rsa/
 obj-$(CONFIG_$(SPL_)SHA1) += sha1.o
 obj-$(CONFIG_$(SPL_)SHA256) += sha256.o
 
+obj-$(CONFIG_SPL_SAVEENV) += qsort.o
 obj-$(CONFIG_$(SPL_)OF_LIBFDT) += libfdt/
 ifneq ($(CONFIG_SPL_BUILD)$(CONFIG_SPL_OF_PLATDATA),yy)
 obj-$(CONFIG_$(SPL_)OF_CONTROL) += fdtdec_common.o

lib/hashtable.c

@@ -477,11 +477,11 @@ int hdelete_r(const char *key, struct hsearch_data *htab, int flag)
 	return 1;
 }
 
+#if !(defined(CONFIG_SPL_BUILD) && !defined(CONFIG_SPL_SAVEENV))
 /*
  * hexport()
  */
 
-#ifndef CONFIG_SPL_BUILD
 /*
  * Export the data stored in the hash table in linearized form.
  *