env_fat: use get_device_and_partition() during env save and load

Use get_device_and_partition() is better since:
1. It will call the device initialize function internally. So we can
remove the mmc intialization code to save many lines.
2. It is used by fatls/fatload/fatwrite. So saveenv & load env should
use it too.
3. It can parse the "D:P", "D", "D:", "D:auto" string to get correct
device and partition information by run-time.

Also we remove the FAT_ENV_DEVICE and FAT_ENV_PART. We use a string:
FAT_ENV_DEVICE_AND_PART.
For at91sam9m10g45ek, it is "0". That means use device 0 and if:
a)device 0 has no partition table, use the whole device as a FAT file
system.
b)device 0 has partittion table, use the partition #1.

Refer to the commit: 10a37fd7a4 for details of device & partition string.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>

common/env_fat.c

@@ -38,39 +38,24 @@ int saveenv(void)
 {
 	env_t	env_new;
 	block_dev_desc_t *dev_desc = NULL;
-	int dev = FAT_ENV_DEVICE;
-	int part = FAT_ENV_PART;
+	disk_partition_t info;
+	int dev, part;
 	int err;
 
 	err = env_export(&env_new);
 	if (err)
 		return err;
 
-#ifdef CONFIG_MMC
-	if (strcmp(FAT_ENV_INTERFACE, "mmc") == 0) {
-		struct mmc *mmc = find_mmc_device(dev);
-
-		if (!mmc) {
-			printf("no mmc device at slot %x\n", dev);
-			return 1;
-		}
-
-		mmc->has_init = 0;
-		mmc_init(mmc);
-	}
-#endif /* CONFIG_MMC */
-
-	dev_desc = get_dev(FAT_ENV_INTERFACE, dev);
-	if (dev_desc == NULL) {
-		printf("Failed to find %s%d\n",
-			FAT_ENV_INTERFACE, dev);
+	part = get_device_and_partition(FAT_ENV_INTERFACE,
+					FAT_ENV_DEVICE_AND_PART,
+					&dev_desc, &info, 1);
+	if (part < 0)
 		return 1;
-	}
 
-	err = fat_register_device(dev_desc, part);
-	if (err) {
-		printf("Failed to register %s%d:%d\n",
-			FAT_ENV_INTERFACE, dev, part);
+	dev = dev_desc->dev;
+	if (fat_set_blk_dev(dev_desc, &info) != 0) {
+		printf("\n** Unable to use %s %d:%d for saveenv **\n",
+		       FAT_ENV_INTERFACE, dev, part);
 		return 1;
 	}
 
@@ -90,48 +75,33 @@ void env_relocate_spec(void)
 {
 	char buf[CONFIG_ENV_SIZE];
 	block_dev_desc_t *dev_desc = NULL;
-	int dev = FAT_ENV_DEVICE;
-	int part = FAT_ENV_PART;
+	disk_partition_t info;
+	int dev, part;
 	int err;
 
-#ifdef CONFIG_MMC
-	if (strcmp(FAT_ENV_INTERFACE, "mmc") == 0) {
-		struct mmc *mmc = find_mmc_device(dev);
-
-		if (!mmc) {
-			printf("no mmc device at slot %x\n", dev);
-			set_default_env(NULL);
-			return;
-		}
-
-		mmc->has_init = 0;
-		mmc_init(mmc);
-	}
-#endif /* CONFIG_MMC */
-
-	dev_desc = get_dev(FAT_ENV_INTERFACE, dev);
-	if (dev_desc == NULL) {
-		printf("Failed to find %s%d\n",
-			FAT_ENV_INTERFACE, dev);
-		set_default_env(NULL);
-		return;
-	}
-
-	err = fat_register_device(dev_desc, part);
-	if (err) {
-		printf("Failed to register %s%d:%d\n",
-			FAT_ENV_INTERFACE, dev, part);
-		set_default_env(NULL);
-		return;
+	part = get_device_and_partition(FAT_ENV_INTERFACE,
+					FAT_ENV_DEVICE_AND_PART,
+					&dev_desc, &info, 1);
+	if (part < 0)
+		goto err_env_relocate;
+
+	dev = dev_desc->dev;
+	if (fat_set_blk_dev(dev_desc, &info) != 0) {
+		printf("\n** Unable to use %s %d:%d for loading the env **\n",
+		       FAT_ENV_INTERFACE, dev, part);
+		goto err_env_relocate;
 	}
 
 	err = file_fat_read(FAT_ENV_FILE, (uchar *)&buf, CONFIG_ENV_SIZE);
 	if (err == -1) {
 		printf("\n** Unable to read \"%s\" from %s%d:%d **\n",
 			FAT_ENV_FILE, FAT_ENV_INTERFACE, dev, part);
-		set_default_env(NULL);
-		return;
+		goto err_env_relocate;
 	}
 
 	env_import(buf, 1);
+	return;
+
+err_env_relocate:
+	set_default_env(NULL);
 }

include/configs/at91sam9m10g45ek.h

@@ -167,8 +167,12 @@
 #elif CONFIG_SYS_USE_MMC
 /* bootstrap + u-boot + env + linux in mmc */
 #define FAT_ENV_INTERFACE	"mmc"
-#define FAT_ENV_DEVICE		0
-#define FAT_ENV_PART		1
+/*
+ * We don't specify the part number, if device 0 has partition table, it means
+ * the first partition; it no partition table, then take whole device as a
+ * FAT file system.
+ */
+#define FAT_ENV_DEVICE_AND_PART	"0"
 #define FAT_ENV_FILE		"uboot.env"
 #define CONFIG_ENV_IS_IN_FAT
 #define CONFIG_FAT_WRITE