openwrt/target/linux/ramips/patches-4.9/0054-mtd-add-chunked-read-io-to-m25p80.patch

--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1453,6 +1453,67 @@ write_err:
 	return ret;
 }
 
+static int spi_nor_chunked_write(struct mtd_info *mtd, loff_t _to, size_t _len,
+				 size_t *_retlen, const u_char *_buf)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	u32 addr_width = nor->addr_width + !!(nor->flags & SNOR_F_4B_EXT_ADDR);
+	int chunk_size;
+	int retlen = 0;
+	int ret;
+
+	chunk_size = nor->chunk_size;
+	if (!chunk_size)
+		chunk_size = _len;
+
+	if (addr_width > 3)
+		chunk_size -= addr_width - 3;
+
+	while (retlen < _len) {
+		size_t len = min_t(int, chunk_size, _len - retlen);
+		const u_char *buf = _buf + retlen;
+		loff_t to = _to + retlen;
+
+		if (nor->flags & SNOR_F_SST)
+			ret = sst_write(mtd, to, len, &retlen, buf);
+		else
+			ret = spi_nor_write(mtd, to, len, &retlen, buf);
+		if (ret)
+			return ret;
+	}
+
+	*_retlen += retlen;
+	return 0;
+}
+
+static int spi_nor_chunked_read(struct mtd_info *mtd, loff_t _from, size_t _len,
+				size_t *_retlen, u_char *_buf)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	int chunk_size;
+	int ret;
+
+	chunk_size = nor->chunk_size;
+	if (!chunk_size)
+		chunk_size = _len;
+
+	*_retlen = 0;
+	while (*_retlen < _len) {
+		size_t len = min_t(int, chunk_size, _len - *_retlen);
+		u_char *buf = _buf + *_retlen;
+		loff_t from = _from + *_retlen;
+		int retlen = 0;
+
+		ret = spi_nor_read(mtd, from, len, &retlen, buf);
+		if (ret)
+			return ret;
+
+		*_retlen += retlen;
+	}
+
+	return 0;
+}
+
 static int macronix_quad_enable(struct spi_nor *nor)
 {
 	int ret, val;
@@ -1704,10 +1765,12 @@ int spi_nor_scan(struct spi_nor *nor, co
 	}
 
 	/* sst nor chips use AAI word program */
-	if (info->flags & SST_WRITE)
+	if (info->flags & SST_WRITE) {
 		mtd->_write = sst_write;
-	else
+		nor->flags |= SNOR_F_SST;
+	} else {
 		mtd->_write = spi_nor_write;
+	}
 
 	if (info->flags & USE_FSR)
 		nor->flags |= SNOR_F_USE_FSR;
@@ -1739,11 +1802,20 @@ int spi_nor_scan(struct spi_nor *nor, co
 	mtd->writebufsize = nor->page_size;
 
 	if (np) {
+		u32 val;
+
 		/* If we were instantiated by DT, use it */
 		if (of_property_read_bool(np, "m25p,fast-read"))
 			nor->flash_read = SPI_NOR_FAST;
 		else
 			nor->flash_read = SPI_NOR_NORMAL;
+
+		if (!of_property_read_u32(np, "m25p,chunked-io", &val)) {
+			dev_info(dev, "using chunked io (size=%d)\n", val);
+			mtd->_read = spi_nor_chunked_read;
+			mtd->_write = spi_nor_chunked_write;
+			nor->chunk_size = val;
+		}
 	} else {
 		/* If we weren't instantiated by DT, default to fast-read */
 		nor->flash_read = SPI_NOR_FAST;
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -143,6 +143,7 @@ enum spi_nor_option_flags {
 	SNOR_F_S3AN_ADDR_DEFAULT = BIT(3),
 	SNOR_F_READY_XSR_RDY	= BIT(4),
 	SNOR_F_4B_EXT_ADDR	= BIT(5),
+	SNOR_F_SST		= BIT(6),
 };
 
 /**
@@ -182,6 +183,7 @@ struct spi_nor {
 	struct mutex		lock;
 	struct device		*dev;
 	u32			page_size;
+	u16			chunk_size;
 	u8			addr_width;
 	u8			erase_opcode;
 	u8			read_opcode;