[PATCH v3 17/22] mtd: spinand: Create direct mapping descriptors for ECC operations

[Miquel Raynal]

In order for pipelined ECC engines to be able to enable/disable the ECC
engine only when needed and avoid races when future parallel-operations
will be supported, we need to provide the information about the use of
the ECC engine in the direct mapping hooks. As direct mapping
configurations are meant to be static, it is best to create two new
mappings: one for regular 'raw' accesses and one for accesses involving
correction. It is up to the driver to use or not the new ECC enable
boolean contained in the spi-mem operation.

As dirmaps are not free (they consume a few pages of MMIO address space)
and because these extra entries are only meant to be used by pipelined
engines, let's limit their use to this specific type of engine and save
a bit of memory with all the other setups.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/nand/spi/core.c | 35 +++++++++++++++++++++++++++++++++--
 include/linux/mtd/spinand.h |  2 ++
 include/linux/spi/spi-mem.h |  3 +++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 715cad26fdef..eb999e47e978 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -381,7 +381,10 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 		}
 	}
 
-	rdesc = spinand->dirmaps[req->pos.plane].rdesc;
+	if (req->mode == MTD_OPS_RAW)
+		rdesc = spinand->dirmaps[req->pos.plane].rdesc;
+	else
+		rdesc = spinand->dirmaps[req->pos.plane].rdesc_ecc;
 
 	while (nbytes) {
 		ret = spi_mem_dirmap_read(rdesc, column, nbytes, buf);
@@ -452,7 +455,10 @@ static int spinand_write_to_cache_op(struct spinand_device *spinand,
 			       req->ooblen);
 	}
 
-	wdesc = spinand->dirmaps[req->pos.plane].wdesc;
+	if (req->mode == MTD_OPS_RAW)
+		wdesc = spinand->dirmaps[req->pos.plane].wdesc;
+	else
+		wdesc = spinand->dirmaps[req->pos.plane].wdesc_ecc;
 
 	while (nbytes) {
 		ret = spi_mem_dirmap_write(wdesc, column, nbytes, buf);
@@ -866,6 +872,31 @@ static int spinand_create_dirmap(struct spinand_device *spinand,
 
 	spinand->dirmaps[plane].rdesc = desc;
 
+	if (nand->ecc.engine->integration != NAND_ECC_ENGINE_INTEGRATION_PIPELINED) {
+		spinand->dirmaps[plane].wdesc_ecc = spinand->dirmaps[plane].wdesc;
+		spinand->dirmaps[plane].rdesc_ecc = spinand->dirmaps[plane].rdesc;
+
+		return 0;
+	}
+
+	info.op_tmpl = *spinand->op_templates.update_cache;
+	info.op_tmpl.ecc_en = true;
+	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
+					  spinand->spimem, &info);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	spinand->dirmaps[plane].wdesc_ecc = desc;
+
+	info.op_tmpl = *spinand->op_templates.read_cache;
+	info.op_tmpl.ecc_en = true;
+	desc = devm_spi_mem_dirmap_create(&spinand->spimem->spi->dev,
+					  spinand->spimem, &info);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	spinand->dirmaps[plane].rdesc_ecc = desc;
+
 	return 0;
 }
 
diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
index 6988956b8492..3aa28240a77f 100644
--- a/include/linux/mtd/spinand.h
+++ b/include/linux/mtd/spinand.h
@@ -389,6 +389,8 @@ struct spinand_info {
 struct spinand_dirmap {
 	struct spi_mem_dirmap_desc *wdesc;
 	struct spi_mem_dirmap_desc *rdesc;
+	struct spi_mem_dirmap_desc *wdesc_ecc;
+	struct spi_mem_dirmap_desc *rdesc_ecc;
 };
 
 /**
diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
index 85e2ff7b840d..3be594be24c0 100644
--- a/include/linux/spi/spi-mem.h
+++ b/include/linux/spi/spi-mem.h
@@ -94,6 +94,7 @@ enum spi_mem_data_dir {
  *		 operation does not involve transferring data
  * @data.buf.in: input buffer (must be DMA-able)
  * @data.buf.out: output buffer (must be DMA-able)
+ * @ecc_en: error correction is required
  */
 struct spi_mem_op {
 	struct {
@@ -126,6 +127,8 @@ struct spi_mem_op {
 			const void *out;
 		} buf;
 	} data;
+
+	bool ecc_en;
 };
 
 #define SPI_MEM_OP(__cmd, __addr, __dummy, __data)		\
-- 
2.27.0