openwrt/target/linux/ramips/patches-3.18/0044-mtd-add-chunked-read-io-to-m25p80.patch

--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -19,6 +19,7 @@
 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/of.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
@@ -32,6 +33,7 @@ struct m25p {
 	struct spi_device	*spi;
 	struct spi_nor		spi_nor;
 	struct mtd_info		mtd;
+	u16			chunk_size;
 	u8			command[MAX_CMD_SIZE];
 };
 
@@ -157,6 +159,61 @@ static int m25p80_read(struct spi_nor *n
 	return 0;
 }
 
+static void m25p80_chunked_write(struct spi_nor *nor, loff_t _from, size_t _len,
+			size_t *_retlen, const u_char *_buf)
+{
+	struct m25p *flash = nor->priv;
+	int chunk_size;
+	int retlen = 0;
+
+	chunk_size = flash->chunk_size;
+	if (!chunk_size)
+		chunk_size = _len;
+
+	if (nor->addr_width > 3)
+		chunk_size -= nor->addr_width - 3;
+
+	while (retlen < _len) {
+		size_t len = min_t(int, chunk_size, _len - retlen);
+		const u_char *buf = _buf + retlen;
+		loff_t from = _from + retlen;
+
+		nor->wait_till_ready(nor);
+		nor->write_reg(nor, SPINOR_OP_WREN, NULL, 0, 0);
+
+		m25p80_write(nor, from, len, &retlen, buf);
+	}
+	*_retlen += retlen;
+}
+
+static int m25p80_chunked_read(struct spi_nor *nor, loff_t _from, size_t _len,
+			size_t *_retlen, u_char *_buf)
+{
+	struct m25p *flash = nor->priv;
+	int chunk_size;
+
+	chunk_size = flash->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;
+		int ret = m25p80_read(nor, from, len, &retlen, buf);
+
+		if (ret)
+			return ret;
+
+		*_retlen += retlen;
+	}
+
+	return 0;
+}
+
 static int m25p80_erase(struct spi_nor *nor, loff_t offset)
 {
 	struct m25p *flash = nor->priv;
@@ -197,6 +254,7 @@ static int m25p_probe(struct spi_device
 	struct spi_nor *nor;
 	enum read_mode mode = SPI_NOR_NORMAL;
 	char *flash_name = NULL;
+	u32 val;
 	int ret;
 
 	data = dev_get_platdata(&spi->dev);
@@ -244,6 +302,14 @@ static int m25p_probe(struct spi_device
 	if (ret)
 		return ret;
 
+	if (spi->dev.of_node &&
+	    !of_property_read_u32(spi->dev.of_node, "m25p,chunked-io", &val)) {
+		dev_warn(&spi->dev, "using chunked io\n");
+		nor->read = m25p80_chunked_read;
+		nor->write = m25p80_chunked_write;
+		flash->chunk_size = val;
+	}
+
 	ppdata.of_node = spi->dev.of_node;
 
 	return mtd_device_parse_register(&flash->mtd, NULL, &ppdata,