mtd: mtdram: Add parameter for setting writebuf size

ubifs uses the write buffer size in recovery algorithm. When inspecting
an unclean ubifs recovery fails with writebuf size 64 in mtdram while
recovery on actual mtd device with writebuf size of 1024 succeeds.
So add a parameter for setting this property.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/devices/mtdram.c

@@ -19,6 +19,7 @@
 
 static unsigned long total_size = CONFIG_MTDRAM_TOTAL_SIZE;
 static unsigned long erase_size = CONFIG_MTDRAM_ERASE_SIZE;
+static unsigned long writebuf_size = 64;
 #define MTDRAM_TOTAL_SIZE (total_size * 1024)
 #define MTDRAM_ERASE_SIZE (erase_size * 1024)
 
@@ -27,6 +28,8 @@ module_param(total_size, ulong, 0);
 MODULE_PARM_DESC(total_size, "Total device size in KiB");
 module_param(erase_size, ulong, 0);
 MODULE_PARM_DESC(erase_size, "Device erase block size in KiB");
+module_param(writebuf_size, ulong, 0);
+MODULE_PARM_DESC(writebuf_size, "Device write buf size in Bytes (Default: 64)");
 #endif
 
 // We could store these in the mtd structure, but we only support 1 device..
@@ -123,7 +126,7 @@ int mtdram_init_device(struct mtd_info *mtd, void *mapped_address,
 	mtd->flags = MTD_CAP_RAM;
 	mtd->size = size;
 	mtd->writesize = 1;
-	mtd->writebufsize = 64; /* Mimic CFI NOR flashes */
+	mtd->writebufsize = writebuf_size;
 	mtd->erasesize = MTDRAM_ERASE_SIZE;
 	mtd->priv = mapped_address;