1 files changed, 168 insertions, 8 deletions

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 1f468ed93c8e..04041287b129 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -200,6 +200,12 @@ static int spinand_ecc_enable(struct spinand_device *spinand,
 			       enable ? CFG_ECC_ENABLE : 0);
 }
 
+static int spinand_cont_read_enable(struct spinand_device *spinand,
+				    bool enable)
+{
+	return spinand->set_cont_read(spinand, enable);
+}
+
 static int spinand_check_ecc_status(struct spinand_device *spinand, u8 status)
 {
 	struct nand_device *nand = spinand_to_nand(spinand);
@@ -311,10 +317,22 @@ static int spinand_ondie_ecc_finish_io_req(struct nand_device *nand,
 
 	/* Finish a page read: check the status, report errors/bitflips */
 	ret = spinand_check_ecc_status(spinand, engine_conf->status);
-	if (ret == -EBADMSG)
+	if (ret == -EBADMSG) {
 		mtd->ecc_stats.failed++;
-	else if (ret > 0)
-		mtd->ecc_stats.corrected += ret;
+	} else if (ret > 0) {
+		unsigned int pages;
+
+		/*
+		 * Continuous reads don't allow us to get the detail,
+		 * so we may exagerate the actual number of corrected bitflips.
+		 */
+		if (!req->continuous)
+			pages = 1;
+		else
+			pages = req->datalen / nanddev_page_size(nand);
+
+		mtd->ecc_stats.corrected += ret * pages;
+	}
 
 	return ret;
 }
@@ -369,7 +387,11 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 
 	if (req->datalen) {
 		buf = spinand->databuf;
-		nbytes = nanddev_page_size(nand);
+		if (!req->continuous)
+			nbytes = nanddev_page_size(nand);
+		else
+			nbytes = round_up(req->dataoffs + req->datalen,
+					  nanddev_page_size(nand));
 		column = 0;
 	}
 
@@ -397,6 +419,13 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 		nbytes -= ret;
 		column += ret;
 		buf += ret;
+
+		/*
+		 * Dirmap accesses are allowed to toggle the CS.
+		 * Toggling the CS during a continuous read is forbidden.
+		 */
+		if (nbytes && req->continuous)
+			return -EIO;
 	}
 
 	if (req->datalen)
@@ -672,6 +701,125 @@ static int spinand_mtd_regular_page_read(struct mtd_info *mtd, loff_t from,
 	return ret;
 }
 
+static int spinand_mtd_continuous_page_read(struct mtd_info *mtd, loff_t from,
+					    struct mtd_oob_ops *ops,
+					    unsigned int *max_bitflips)
+{
+	struct spinand_device *spinand = mtd_to_spinand(mtd);
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	struct nand_io_iter iter;
+	u8 status;
+	int ret;
+
+	ret = spinand_cont_read_enable(spinand, true);
+	if (ret)
+		return ret;
+
+	/*
+	 * The cache is divided into two halves. While one half of the cache has
+	 * the requested data, the other half is loaded with the next chunk of data.
+	 * Therefore, the host can read out the data continuously from page to page.
+	 * Each data read must be a multiple of 4-bytes and full pages should be read;
+	 * otherwise, the data output might get out of sequence from one read command
+	 * to another.
+	 */
+	nanddev_io_for_each_block(nand, NAND_PAGE_READ, from, ops, &iter) {
+		ret = spinand_select_target(spinand, iter.req.pos.target);
+		if (ret)
+			goto end_cont_read;
+
+		ret = nand_ecc_prepare_io_req(nand, &iter.req);
+		if (ret)
+			goto end_cont_read;
+
+		ret = spinand_load_page_op(spinand, &iter.req);
+		if (ret)
+			goto end_cont_read;
+
+		ret = spinand_wait(spinand, SPINAND_READ_INITIAL_DELAY_US,
+				   SPINAND_READ_POLL_DELAY_US, NULL);
+		if (ret < 0)
+			goto end_cont_read;
+
+		ret = spinand_read_from_cache_op(spinand, &iter.req);
+		if (ret)
+			goto end_cont_read;
+
+		ops->retlen += iter.req.datalen;
+
+		ret = spinand_read_status(spinand, &status);
+		if (ret)
+			goto end_cont_read;
+
+		spinand_ondie_ecc_save_status(nand, status);
+
+		ret = nand_ecc_finish_io_req(nand, &iter.req);
+		if (ret < 0)
+			goto end_cont_read;
+
+		*max_bitflips = max_t(unsigned int, *max_bitflips, ret);
+		ret = 0;
+	}
+
+end_cont_read:
+	/*
+	 * Once all the data has been read out, the host can either pull CS#
+	 * high and wait for tRST or manually clear the bit in the configuration
+	 * register to terminate the continuous read operation. We have no
+	 * guarantee the SPI controller drivers will effectively deassert the CS
+	 * when we expect them to, so take the register based approach.
+	 */
+	spinand_cont_read_enable(spinand, false);
+
+	return ret;
+}
+
+static void spinand_cont_read_init(struct spinand_device *spinand)
+{
+	struct nand_device *nand = spinand_to_nand(spinand);
+	enum nand_ecc_engine_type engine_type = nand->ecc.ctx.conf.engine_type;
+
+	/* OOBs cannot be retrieved so external/on-host ECC engine won't work */
+	if (spinand->set_cont_read &&
+	    (engine_type == NAND_ECC_ENGINE_TYPE_ON_DIE ||
+	     engine_type == NAND_ECC_ENGINE_TYPE_NONE)) {
+		spinand->cont_read_possible = true;
+	}
+}
+
+static bool spinand_use_cont_read(struct mtd_info *mtd, loff_t from,
+				  struct mtd_oob_ops *ops)
+{
+	struct nand_device *nand = mtd_to_nanddev(mtd);
+	struct spinand_device *spinand = nand_to_spinand(nand);
+	struct nand_pos start_pos, end_pos;
+
+	if (!spinand->cont_read_possible)
+		return false;
+
+	/* OOBs won't be retrieved */
+	if (ops->ooblen || ops->oobbuf)
+		return false;
+
+	nanddev_offs_to_pos(nand, from, &start_pos);
+	nanddev_offs_to_pos(nand, from + ops->len - 1, &end_pos);
+
+	/*
+	 * Continuous reads never cross LUN boundaries. Some devices don't
+	 * support crossing planes boundaries. Some devices don't even support
+	 * crossing blocks boundaries. The common case being to read through UBI,
+	 * we will very rarely read two consequent blocks or more, so it is safer
+	 * and easier (can be improved) to only enable continuous reads when
+	 * reading within the same erase block.
+	 */
+	if (start_pos.target != end_pos.target ||
+	    start_pos.plane != end_pos.plane ||
+	    start_pos.eraseblock != end_pos.eraseblock)
+		return false;
+
+	return start_pos.page < end_pos.page;
+}
+
 static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 			    struct mtd_oob_ops *ops)
 {
@@ -684,7 +832,10 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 
 	old_stats = mtd->ecc_stats;
 
-	ret = spinand_mtd_regular_page_read(mtd, from, ops, &max_bitflips);
+	if (spinand_use_cont_read(mtd, from, ops))
+		ret = spinand_mtd_continuous_page_read(mtd, from, ops, &max_bitflips);
+	else
+		ret = spinand_mtd_regular_page_read(mtd, from, ops, &max_bitflips);
 
 	if (ops->stats) {
 		ops->stats->uncorrectable_errors +=
@@ -874,6 +1025,9 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 	};
 	struct spi_mem_dirmap_desc *desc;
 
+	if (spinand->cont_read_possible)
+		info.length = nanddev_eraseblock_size(nand);
+
 	/* The plane number is passed in MSB just above the column address */
 	info.offset = plane << fls(nand->memorg.pagesize);
 
@@ -1107,6 +1261,7 @@ int spinand_match_and_init(struct spinand_device *spinand,
 		spinand->flags = table[i].flags;
 		spinand->id.len = 1 + table[i].devid.len;
 		spinand->select_target = table[i].select_target;
+		spinand->set_cont_read = table[i].set_cont_read;
 
 		op = spinand_select_op_variant(spinand,
 					       info->op_variants.read_cache);
@@ -1248,9 +1403,8 @@ static int spinand_init(struct spinand_device *spinand)
 	 * may use this buffer for DMA access.
 	 * Memory allocated by devm_ does not guarantee DMA-safe alignment.
 	 */
-	spinand->databuf = kzalloc(nanddev_page_size(nand) +
-			       nanddev_per_page_oobsize(nand),
-			       GFP_KERNEL);
+	spinand->databuf = kzalloc(nanddev_eraseblock_size(nand),
+				   GFP_KERNEL);
 	if (!spinand->databuf) {
 		ret = -ENOMEM;
 		goto err_free_bufs;
@@ -1279,6 +1433,12 @@ static int spinand_init(struct spinand_device *spinand)
 	if (ret)
 		goto err_cleanup_nanddev;
 
+	/*
+	 * Continuous read can only be enabled with an on-die ECC engine, so the
+	 * ECC initialization must have happened previously.
+	 */
+	spinand_cont_read_init(spinand);
+
 	mtd->_read_oob = spinand_mtd_read;
 	mtd->_write_oob = spinand_mtd_write;
 	mtd->_block_isbad = spinand_mtd_block_isbad;