[RFC PATCH v5 5/6] mtd: rawnand: meson: check buffer length

[Arseniy Krasnov]

This NAND controller has limited buffer length, so check it before
command execution to avoid length trim. Also check MTD write size on
chip attach.

Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
 Changelog v4->v5:
 * Move length checks from functions 'meson_nfc_read/write_buf()' to
   'meson_nfc_exec_op()'.

 drivers/mtd/nand/raw/meson_nand.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
index 23a73268421b..2a91916566f4 100644
--- a/drivers/mtd/nand/raw/meson_nand.c
+++ b/drivers/mtd/nand/raw/meson_nand.c
@@ -111,6 +111,8 @@
 #define NFC_USER_BYTES		2
 #define NFC_OOB_PER_ECC(nand)	((nand)->ecc.bytes + NFC_USER_BYTES)
 
+#define NFC_CMD_RAW_LEN		GENMASK(13, 0)
+
 struct meson_nfc_nand_chip {
 	struct list_head node;
 	struct nand_chip nand;
@@ -284,7 +286,7 @@ static void meson_nfc_cmd_access(struct nand_chip *nand, int raw, bool dir,
 
 	if (raw) {
 		len = mtd->writesize + mtd->oobsize;
-		cmd = (len & GENMASK(13, 0)) | scrambler | DMA_DIR(dir);
+		cmd = len | scrambler | DMA_DIR(dir);
 		writel(cmd, nfc->reg_base + NFC_REG_CMD);
 		return;
 	}
@@ -573,7 +575,7 @@ static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, int len)
 	if (ret)
 		goto out;
 
-	cmd = NFC_CMD_N2M | (len & GENMASK(13, 0));
+	cmd = NFC_CMD_N2M | len;
 	writel(cmd, nfc->reg_base + NFC_REG_CMD);
 
 	meson_nfc_drain_cmd(nfc);
@@ -597,7 +599,7 @@ static int meson_nfc_write_buf(struct nand_chip *nand, u8 *buf, int len)
 	if (ret)
 		return ret;
 
-	cmd = NFC_CMD_M2N | (len & GENMASK(13, 0));
+	cmd = NFC_CMD_M2N | len;
 	writel(cmd, nfc->reg_base + NFC_REG_CMD);
 
 	meson_nfc_drain_cmd(nfc);
@@ -1044,6 +1046,9 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
 			break;
 
 		case NAND_OP_DATA_IN_INSTR:
+			if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
+				return -EINVAL;
+
 			buf = meson_nand_op_get_dma_safe_input_buf(instr);
 			if (!buf)
 				return -ENOMEM;
@@ -1052,6 +1057,9 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
 			break;
 
 		case NAND_OP_DATA_OUT_INSTR:
+			if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
+				return -EINVAL;
+
 			buf = meson_nand_op_get_dma_safe_output_buf(instr);
 			if (!buf)
 				return -ENOMEM;
@@ -1293,6 +1301,7 @@ static int meson_nand_attach_chip(struct nand_chip *nand)
 	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	int nsectors = mtd->writesize / 1024;
+	int raw_writesize;
 	int ret;
 
 	if (!mtd->name) {
@@ -1304,6 +1313,13 @@ static int meson_nand_attach_chip(struct nand_chip *nand)
 			return -ENOMEM;
 	}
 
+	raw_writesize = mtd->writesize + mtd->oobsize;
+	if (raw_writesize > NFC_CMD_RAW_LEN) {
+		dev_err(nfc->dev, "too big write size in raw mode: %d > %ld\n",
+			raw_writesize, NFC_CMD_RAW_LEN);
+		return -EINVAL;
+	}
+
 	if (nand->bbt_options & NAND_BBT_USE_FLASH)
 		nand->bbt_options |= NAND_BBT_NO_OOB;
 
-- 
2.35.0