mtd: rawnand: Provide a helper to get chip->data_buf

We plan to move cache related fields to a pagecache struct in nand_chip
but some drivers access ->pagebuf directly to invalidate the cache
before they start using ->data_buf.

Let's provide an helper that returns a pointer to ->data_buf after
invalidating the cache.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>

drivers/mtd/nand/raw/brcmnand/brcmnand.c

@@ -1676,11 +1676,8 @@ static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,
 	int page = addr >> chip->page_shift;
 	int ret;
 
-	if (!buf) {
-		buf = chip->data_buf;
-		/* Invalidate page cache */
-		chip->pagebuf = -1;
-	}
+	if (!buf)
+		buf = nand_get_data_buf(chip);
 
 	sas = mtd->oobsize / chip->ecc.steps;
 

drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c

@@ -1602,7 +1602,7 @@ static int mx23_check_transcription_stamp(struct gpmi_nand_data *this)
 	unsigned int search_area_size_in_strides;
 	unsigned int stride;
 	unsigned int page;
-	uint8_t *buffer = chip->data_buf;
+	u8 *buffer = nand_get_data_buf(chip);
 	int saved_chip_number;
 	int found_an_ncb_fingerprint = false;
 
@@ -1664,7 +1664,7 @@ static int mx23_write_transcription_stamp(struct gpmi_nand_data *this)
 	unsigned int block;
 	unsigned int stride;
 	unsigned int page;
-	uint8_t      *buffer = chip->data_buf;
+	u8 *buffer = nand_get_data_buf(chip);
 	int saved_chip_number;
 	int status;
 

drivers/mtd/nand/raw/marvell_nand.c

@@ -1083,12 +1083,11 @@ static int marvell_nfc_hw_ecc_hmg_read_page(struct nand_chip *chip, u8 *buf,
  */
 static int marvell_nfc_hw_ecc_hmg_read_oob_raw(struct nand_chip *chip, int page)
 {
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
+	u8 *buf = nand_get_data_buf(chip);
 
 	marvell_nfc_select_target(chip, chip->cur_cs);
-	return marvell_nfc_hw_ecc_hmg_do_read_page(chip, chip->data_buf,
-						   chip->oob_poi, true, page);
+	return marvell_nfc_hw_ecc_hmg_do_read_page(chip, buf, chip->oob_poi,
+						   true, page);
 }
 
 /* Hamming write helpers */
@@ -1179,15 +1178,13 @@ static int marvell_nfc_hw_ecc_hmg_write_oob_raw(struct nand_chip *chip,
 						int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	u8 *buf = nand_get_data_buf(chip);
 
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
-
-	memset(chip->data_buf, 0xFF, mtd->writesize);
+	memset(buf, 0xFF, mtd->writesize);
 
 	marvell_nfc_select_target(chip, chip->cur_cs);
-	return marvell_nfc_hw_ecc_hmg_do_write_page(chip, chip->data_buf,
-						    chip->oob_poi, true, page);
+	return marvell_nfc_hw_ecc_hmg_do_write_page(chip, buf, chip->oob_poi,
+						    true, page);
 }
 
 /* BCH read helpers */
@@ -1434,18 +1431,16 @@ static int marvell_nfc_hw_ecc_bch_read_page(struct nand_chip *chip,
 
 static int marvell_nfc_hw_ecc_bch_read_oob_raw(struct nand_chip *chip, int page)
 {
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
+	u8 *buf = nand_get_data_buf(chip);
 
-	return chip->ecc.read_page_raw(chip, chip->data_buf, true, page);
+	return chip->ecc.read_page_raw(chip, buf, true, page);
 }
 
 static int marvell_nfc_hw_ecc_bch_read_oob(struct nand_chip *chip, int page)
 {
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
+	u8 *buf = nand_get_data_buf(chip);
 
-	return chip->ecc.read_page(chip, chip->data_buf, true, page);
+	return chip->ecc.read_page(chip, buf, true, page);
 }
 
 /* BCH write helpers */
@@ -1619,25 +1614,21 @@ static int marvell_nfc_hw_ecc_bch_write_oob_raw(struct nand_chip *chip,
 						int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	u8 *buf = nand_get_data_buf(chip);
 
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
-
-	memset(chip->data_buf, 0xFF, mtd->writesize);
+	memset(buf, 0xFF, mtd->writesize);
 
-	return chip->ecc.write_page_raw(chip, chip->data_buf, true, page);
+	return chip->ecc.write_page_raw(chip, buf, true, page);
 }
 
 static int marvell_nfc_hw_ecc_bch_write_oob(struct nand_chip *chip, int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	u8 *buf = nand_get_data_buf(chip);
 
-	/* Invalidate page cache */
-	chip->pagebuf = -1;
-
-	memset(chip->data_buf, 0xFF, mtd->writesize);
+	memset(buf, 0xFF, mtd->writesize);
 
-	return chip->ecc.write_page(chip, chip->data_buf, true, page);
+	return chip->ecc.write_page(chip, buf, true, page);
 }
 
 /* NAND framework ->exec_op() hooks and related helpers */

drivers/mtd/nand/raw/nand_base.c

@@ -4004,10 +4004,9 @@ static int nand_do_write_ops(struct nand_chip *chip, loff_t to,
 					 __func__, buf);
 			if (part_pagewr)
 				bytes = min_t(int, bytes - column, writelen);
-			chip->pagebuf = -1;
-			memset(chip->data_buf, 0xff, mtd->writesize);
-			memcpy(&chip->data_buf[column], buf, bytes);
-			wbuf = chip->data_buf;
+			wbuf = nand_get_data_buf(chip);
+			memset(wbuf, 0xff, mtd->writesize);
+			memcpy(&wbuf[column], buf, bytes);
 		}
 
 		if (unlikely(oob)) {

drivers/mtd/nand/raw/nand_bbt.c

@@ -901,7 +901,9 @@ static int write_bbt(struct nand_chip *this, uint8_t *buf,
 static inline int nand_memory_bbt(struct nand_chip *this,
 				  struct nand_bbt_descr *bd)
 {
-	return create_bbt(this, this->data_buf, bd, -1);
+	u8 *pagebuf = nand_get_data_buf(this);
+
+	return create_bbt(this, pagebuf, bd, -1);
 }
 
 /**

drivers/mtd/nand/raw/qcom_nandc.c

@@ -1680,14 +1680,12 @@ check_for_erased_page(struct qcom_nand_host *host, u8 *data_buf,
 	u8 *cw_data_buf, *cw_oob_buf;
 	int cw, data_size, oob_size, ret = 0;
 
-	if (!data_buf) {
-		data_buf = chip->data_buf;
-		chip->pagebuf = -1;
-	}
+	if (!data_buf)
+		data_buf = nand_get_data_buf(chip);
 
 	if (!oob_buf) {
+		nand_get_data_buf(chip);
 		oob_buf = chip->oob_poi;
-		chip->pagebuf = -1;
 	}
 
 	for_each_set_bit(cw, &uncorrectable_cws, ecc->steps) {

drivers/mtd/nand/raw/sunxi_nand.c

@@ -1313,20 +1313,19 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 
 static int sunxi_nfc_hw_ecc_read_oob(struct nand_chip *nand, int page)
 {
-	nand->pagebuf = -1;
+	u8 *buf = nand_get_data_buf(nand);
 
-	return nand->ecc.read_page(nand, nand->data_buf, 1, page);
+	return nand->ecc.read_page(nand, buf, 1, page);
 }
 
 static int sunxi_nfc_hw_ecc_write_oob(struct nand_chip *nand, int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(nand);
+	u8 *buf = nand_get_data_buf(nand);
 	int ret;
 
-	nand->pagebuf = -1;
-
-	memset(nand->data_buf, 0xff, mtd->writesize);
-	ret = nand->ecc.write_page(nand, nand->data_buf, 1, page);
+	memset(buf, 0xff, mtd->writesize);
+	ret = nand->ecc.write_page(nand, buf, 1, page);
 	if (ret)
 		return ret;
 

include/linux/mtd/rawnand.h

@@ -1350,4 +1350,25 @@ int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
 void nand_select_target(struct nand_chip *chip, unsigned int cs);
 void nand_deselect_target(struct nand_chip *chip);
 
+/**
+ * nand_get_data_buf() - Get the internal page buffer
+ * @chip: NAND chip object
+ *
+ * Returns the pre-allocated page buffer after invalidating the cache. This
+ * function should be used by drivers that do not want to allocate their own
+ * bounce buffer and still need such a buffer for specific operations (most
+ * commonly when reading OOB data only).
+ *
+ * Be careful to never call this function in the write/write_oob path, because
+ * the core may have placed the data to be written out in this buffer.
+ *
+ * Return: pointer to the page cache buffer
+ */
+static inline void *nand_get_data_buf(struct nand_chip *chip)
+{
+	chip->pagebuf = -1;
+
+	return chip->data_buf;
+}
+
 #endif /* __LINUX_MTD_RAWNAND_H */