[PATCH v3] mtd: rawnand: meson: check buffer length

[Arseniy Krasnov]

Meson 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:

 v1 -> v2:
 * Move checks from 'switch/case' which executes commands in 'meson_nfc_exec_op()'
   to a special separated function 'meson_nfc_check_op()' which is called before
   commands processing.
 v2 -> v3:
 * Check value returned from 'meson_nfc_check_op()' in separated 'if()', e.g.
   without ORing it with 'check_only'.

 drivers/mtd/nand/raw/meson_nand.c | 46 +++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
index 074e14225c06..5c034988cd13 100644
--- a/drivers/mtd/nand/raw/meson_nand.c
+++ b/drivers/mtd/nand/raw/meson_nand.c
@@ -108,6 +108,8 @@
 
 #define PER_INFO_BYTE		8
 
+#define NFC_CMD_RAW_LEN	GENMASK(13, 0)
+
 struct meson_nfc_nand_chip {
 	struct list_head node;
 	struct nand_chip nand;
@@ -280,7 +282,7 @@ 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;
 	}
@@ -544,7 +546,7 @@ 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);
@@ -568,7 +570,7 @@ 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);
@@ -899,6 +901,31 @@ meson_nand_op_put_dma_safe_output_buf(const struct nand_op_instr *instr,
 		kfree(buf);
 }
 
+static int meson_nfc_check_op(struct nand_chip *chip,
+			      const struct nand_operation *op)
+{
+	int op_id;
+
+	for (op_id = 0; op_id < op->ninstrs; op_id++) {
+		const struct nand_op_instr *instr;
+
+		instr = &op->instrs[op_id];
+
+		switch (instr->type) {
+		case NAND_OP_DATA_IN_INSTR:
+		case NAND_OP_DATA_OUT_INSTR:
+			if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
+				return -ENOTSUPP;
+
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 0;
+}
+
 static int meson_nfc_exec_op(struct nand_chip *nand,
 			     const struct nand_operation *op, bool check_only)
 {
@@ -907,8 +934,13 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
 	const struct nand_op_instr *instr = NULL;
 	void *buf;
 	u32 op_id, delay_idle, cmd;
+	int err;
 	int i;
 
+	err = meson_nfc_check_op(nand, op);
+	if (err)
+		return err;
+
 	if (check_only)
 		return 0;
 
@@ -1181,6 +1213,7 @@ 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) {
@@ -1192,6 +1225,13 @@ 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