mtd: rawnand: Expose monolithic read/write_page_raw() helpers

The current nand_read/write_page_raw() helpers are already widely used
but do not fit the purpose of "constrained" controllers which cannot,
for instance, separate command/address cycles with data cycles.

Workaround this issue by proposing alternative helpers that can be
used by these controller drivers instead.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200507105241.14299-12-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/nand_base.c

@@ -2688,6 +2688,47 @@ int nand_read_page_raw(struct nand_chip *chip, uint8_t *buf, int oob_required,
 }
 EXPORT_SYMBOL(nand_read_page_raw);
 
+/**
+ * nand_monolithic_read_page_raw - Monolithic page read in raw mode
+ * @chip: NAND chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * This is a raw page read, ie. without any error detection/correction.
+ * Monolithic means we are requesting all the relevant data (main plus
+ * eventually OOB) to be loaded in the NAND cache and sent over the
+ * bus (from the NAND chip to the NAND controller) in a single
+ * operation. This is an alternative to nand_read_page_raw(), which
+ * first reads the main data, and if the OOB data is requested too,
+ * then reads more data on the bus.
+ */
+int nand_monolithic_read_page_raw(struct nand_chip *chip, u8 *buf,
+				  int oob_required, int page)
+{
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	unsigned int size = mtd->writesize;
+	u8 *read_buf = buf;
+	int ret;
+
+	if (oob_required) {
+		size += mtd->oobsize;
+
+		if (buf != chip->data_buf)
+			read_buf = nand_get_data_buf(chip);
+	}
+
+	ret = nand_read_page_op(chip, page, 0, read_buf, size);
+	if (ret)
+		return ret;
+
+	if (buf != chip->data_buf)
+		memcpy(buf, read_buf, mtd->writesize);
+
+	return 0;
+}
+EXPORT_SYMBOL(nand_monolithic_read_page_raw);
+
 /**
  * nand_read_page_raw_syndrome - [INTERN] read raw page data without ecc
  * @chip: nand chip info structure
@@ -3696,6 +3737,42 @@ int nand_write_page_raw(struct nand_chip *chip, const uint8_t *buf,
 }
 EXPORT_SYMBOL(nand_write_page_raw);
 
+/**
+ * nand_monolithic_write_page_raw - Monolithic page write in raw mode
+ * @chip: NAND chip info structure
+ * @buf: data buffer to write
+ * @oob_required: must write chip->oob_poi to OOB
+ * @page: page number to write
+ *
+ * This is a raw page write, ie. without any error detection/correction.
+ * Monolithic means we are requesting all the relevant data (main plus
+ * eventually OOB) to be sent over the bus and effectively programmed
+ * into the NAND chip arrays in a single operation. This is an
+ * alternative to nand_write_page_raw(), which first sends the main
+ * data, then eventually send the OOB data by latching more data
+ * cycles on the NAND bus, and finally sends the program command to
+ * synchronyze the NAND chip cache.
+ */
+int nand_monolithic_write_page_raw(struct nand_chip *chip, const u8 *buf,
+				   int oob_required, int page)
+{
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	unsigned int size = mtd->writesize;
+	u8 *write_buf = (u8 *)buf;
+
+	if (oob_required) {
+		size += mtd->oobsize;
+
+		if (buf != chip->data_buf) {
+			write_buf = nand_get_data_buf(chip);
+			memcpy(write_buf, buf, mtd->writesize);
+		}
+	}
+
+	return nand_prog_page_op(chip, page, 0, write_buf, size);
+}
+EXPORT_SYMBOL(nand_monolithic_write_page_raw);
+
 /**
  * nand_write_page_raw_syndrome - [INTERN] raw page write function
  * @chip: nand chip info structure

include/linux/mtd/rawnand.h

@@ -1328,13 +1328,17 @@ int nand_read_oob_std(struct nand_chip *chip, int page);
 int nand_get_set_features_notsupp(struct nand_chip *chip, int addr,
 				  u8 *subfeature_param);
 
-/* Default read_page_raw implementation */
+/* read_page_raw implementations */
 int nand_read_page_raw(struct nand_chip *chip, uint8_t *buf, int oob_required,
 		       int page);
+int nand_monolithic_read_page_raw(struct nand_chip *chip, uint8_t *buf,
+				  int oob_required, int page);
 
-/* Default write_page_raw implementation */
+/* write_page_raw implementations */
 int nand_write_page_raw(struct nand_chip *chip, const uint8_t *buf,
 			int oob_required, int page);
+int nand_monolithic_write_page_raw(struct nand_chip *chip, const uint8_t *buf,
+				   int oob_required, int page);
 
 /* Reset and initialize a NAND device */
 int nand_reset(struct nand_chip *chip, int chipnr);