mflash: Initial mflash support

Mflash is fusion memory device mainly targeted consumer eletronic and
mobile phone.
Internally, it have nand flash and other hardware logics and supports
some different operation (ATA, IO, XIP) modes.

IO mode is custom mode for the host that doesn't have IDE interface.
(Many mobile targeted SoC doesn't have IDE bus)

This driver support mflash IO mode.

Followings are brief descriptions about IO mode.

1. IO mode based on ATA protocol and uses some custom command. (read
   confirm, write confirm)
2. IO mode uses SRAM bus interface.

Signed-off-by: unsik Kim <donari75@gmail.com>
diff --git a/common/env_mgdisk.c b/common/env_mgdisk.c
new file mode 100644
index 0000000..363ee68
--- /dev/null
+++ b/common/env_mgdisk.c
@@ -0,0 +1,92 @@
+/*
+ * (C) Copyright 2009 mGine co.
+ * unsik Kim <donari75@gmail.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <command.h>
+#include <environment.h>
+#include <linux/stddef.h>
+#include <mg_disk.h>
+
+/* references to names in env_common.c */
+extern uchar default_environment[];
+extern int default_environment_size;
+
+char * env_name_spec = "MG_DISK";
+
+env_t *env_ptr = 0;
+
+DECLARE_GLOBAL_DATA_PTR;
+
+uchar env_get_char_spec(int index)
+{
+	return (*((uchar *) (gd->env_addr + index)));
+}
+
+void env_relocate_spec(void)
+{
+	unsigned int err;
+
+	err = mg_disk_init();
+	if (err) {
+		puts ("*** Warning - mg_disk_init error");
+		goto OUT;
+	}
+	err = mg_disk_read(CONFIG_ENV_ADDR, (u_char *)env_ptr, CONFIG_ENV_SIZE);
+	if (err) {
+		puts ("*** Warning - mg_disk_read error");
+		goto OUT;
+	}
+
+	if (crc32(0, env_ptr->data, ENV_SIZE) != env_ptr->crc) {
+		puts ("*** Warning - CRC error");
+		goto OUT;
+	}
+
+	return;
+
+OUT:
+	printf (", using default environment\n\n");
+	set_default_env();
+}
+
+int saveenv(void)
+{
+	unsigned int err;
+
+	env_ptr->crc = crc32(0, env_ptr->data, ENV_SIZE);
+	err = mg_disk_write(CONFIG_ENV_ADDR, (u_char *)env_ptr,
+			CONFIG_ENV_SIZE);
+	if (err)
+		puts ("*** Warning - mg_disk_write error\n\n");
+
+	return err;
+}
+
+int env_init(void)
+{
+	/* use default */
+	gd->env_addr = (ulong) & default_environment[0];
+	gd->env_valid = 1;
+
+	return 0;
+}