[MTD] OneNAND: Invalidate bufferRAM after erase

OneNAND has internal bufferRAMs.  The driver keeps track of
what is in the bufferRAM to save having to load from the
NAND core.  After an erase operation, the driver must
mark bufferRAM invalid if it refers to the erased block.
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/onenand/onenand_base.c

@@ -635,6 +635,29 @@ static void onenand_update_bufferram(struct mtd_info *mtd, loff_t addr,
 		this->bufferram[i].blockpage = -1;
 }
 
+/**
+ * onenand_invalidate_bufferram - [GENERIC] Invalidate BufferRAM information
+ * @param mtd		MTD data structure
+ * @param addr		start address to invalidate
+ * @param len		length to invalidate
+ *
+ * Invalidate BufferRAM information
+ */
+static void onenand_invalidate_bufferram(struct mtd_info *mtd, loff_t addr,
+		unsigned int len)
+{
+	struct onenand_chip *this = mtd->priv;
+	int i;
+	loff_t end_addr = addr + len;
+
+	/* Invalidate BufferRAM */
+	for (i = 0; i < MAX_BUFFERRAM; i++) {
+		loff_t buf_addr = this->bufferram[i].blockpage << this->page_shift;
+		if (buf_addr >= addr && buf_addr < end_addr)
+			this->bufferram[i].blockpage = -1;
+	}
+}
+
 /**
  * onenand_get_device - [GENERIC] Get chip for selected access
  * @param mtd		MTD device structure
@@ -1476,6 +1499,8 @@ static int onenand_erase(struct mtd_info *mtd, struct erase_info *instr)
 
 		this->command(mtd, ONENAND_CMD_ERASE, addr, block_size);
 
+		onenand_invalidate_bufferram(mtd, addr, block_size);
+
 		ret = this->wait(mtd, FL_ERASING);
 		/* Check, if it is write protected */
 		if (ret) {