mtd: add MEMERASE64 ioctl for >4GiB devices

New MEMERASE/MEMREADOOB/MEMWRITEOOB ioctls are needed in order to support
64-bit offsets into large NAND flash devices.

Signed-off-by: Kevin Cernekee <kpc.mtd@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 763d3f0..ad4b861 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -417,6 +417,7 @@
 		break;
 
 	case MEMERASE:
+	case MEMERASE64:
 	{
 		struct erase_info *erase;
 
@@ -427,20 +428,32 @@
 		if (!erase)
 			ret = -ENOMEM;
 		else {
-			struct erase_info_user einfo;
-
 			wait_queue_head_t waitq;
 			DECLARE_WAITQUEUE(wait, current);
 
 			init_waitqueue_head(&waitq);
 
-			if (copy_from_user(&einfo, argp,
-				    sizeof(struct erase_info_user))) {
-				kfree(erase);
-				return -EFAULT;
+			if (cmd == MEMERASE64) {
+				struct erase_info_user64 einfo64;
+
+				if (copy_from_user(&einfo64, argp,
+					    sizeof(struct erase_info_user64))) {
+					kfree(erase);
+					return -EFAULT;
+				}
+				erase->addr = einfo64.start;
+				erase->len = einfo64.length;
+			} else {
+				struct erase_info_user einfo32;
+
+				if (copy_from_user(&einfo32, argp,
+					    sizeof(struct erase_info_user))) {
+					kfree(erase);
+					return -EFAULT;
+				}
+				erase->addr = einfo32.start;
+				erase->len = einfo32.length;
 			}
-			erase->addr = einfo.start;
-			erase->len = einfo.length;
 			erase->mtd = mtd;
 			erase->callback = mtdchar_erase_callback;
 			erase->priv = (unsigned long)&waitq;