mtd: spinand: Instantiate a SPI-NAND on-die ECC engine

Make use of the existing functions taken from the SPI-NAND core to
instantiate an on-die ECC engine specific to the SPI-NAND core. The
next step will be to tweak the core to use this object instead of
calling the helpers directly.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200930154109.3922-4-miquel.raynal@bootlin.com

drivers/mtd/nand/spi/core.c

@@ -246,6 +246,73 @@ static const struct mtd_ooblayout_ops spinand_noecc_ooblayout = {
 	.free = spinand_noecc_ooblayout_free,
 };
 
+static int spinand_ondie_ecc_init_ctx(struct nand_device *nand)
+{
+	struct spinand_device *spinand = nand_to_spinand(nand);
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	struct spinand_ondie_ecc_conf *engine_conf;
+
+	nand->ecc.ctx.conf.engine_type = NAND_ECC_ENGINE_TYPE_ON_DIE;
+	nand->ecc.ctx.conf.step_size = nand->ecc.requirements.step_size;
+	nand->ecc.ctx.conf.strength = nand->ecc.requirements.strength;
+
+	engine_conf = kzalloc(sizeof(*engine_conf), GFP_KERNEL);
+	if (!engine_conf)
+		return -ENOMEM;
+
+	nand->ecc.ctx.priv = engine_conf;
+
+	if (spinand->eccinfo.ooblayout)
+		mtd_set_ooblayout(mtd, spinand->eccinfo.ooblayout);
+	else
+		mtd_set_ooblayout(mtd, &spinand_noecc_ooblayout);
+
+	return 0;
+}
+
+static void spinand_ondie_ecc_cleanup_ctx(struct nand_device *nand)
+{
+	kfree(nand->ecc.ctx.priv);
+}
+
+static int spinand_ondie_ecc_prepare_io_req(struct nand_device *nand,
+					    struct nand_page_io_req *req)
+{
+	struct spinand_device *spinand = nand_to_spinand(nand);
+	bool enable = (req->mode != MTD_OPS_RAW);
+
+	/* Only enable or disable the engine */
+	return spinand_ecc_enable(spinand, enable);
+}
+
+static int spinand_ondie_ecc_finish_io_req(struct nand_device *nand,
+					   struct nand_page_io_req *req)
+{
+	struct spinand_ondie_ecc_conf *engine_conf = nand->ecc.ctx.priv;
+	struct spinand_device *spinand = nand_to_spinand(nand);
+
+	if (req->mode == MTD_OPS_RAW)
+		return 0;
+
+	/* Nothing to do when finishing a page write */
+	if (req->type == NAND_PAGE_WRITE)
+		return 0;
+
+	/* Finish a page write: check the status, report errors/bitflips */
+	return spinand_check_ecc_status(spinand, engine_conf->status);
+}
+
+static struct nand_ecc_engine_ops spinand_ondie_ecc_engine_ops = {
+	.init_ctx = spinand_ondie_ecc_init_ctx,
+	.cleanup_ctx = spinand_ondie_ecc_cleanup_ctx,
+	.prepare_io_req = spinand_ondie_ecc_prepare_io_req,
+	.finish_io_req = spinand_ondie_ecc_finish_io_req,
+};
+
+static __maybe_unused struct nand_ecc_engine spinand_ondie_ecc_engine = {
+	.ops = &spinand_ondie_ecc_engine_ops,
+};
+
 static int spinand_write_enable_op(struct spinand_device *spinand)
 {
 	struct spi_mem_op op = SPINAND_WR_EN_DIS_OP(true);

include/linux/mtd/spinand.h

@@ -286,6 +286,15 @@ struct spinand_ecc_info {
 #define SPINAND_HAS_QE_BIT		BIT(0)
 #define SPINAND_HAS_CR_FEAT_BIT		BIT(1)
 
+/**
+ * struct spinand_ondie_ecc_conf - private SPI-NAND on-die ECC engine structure
+ * @status: status of the last wait operation that will be used in case
+ *          ->get_status() is not populated by the spinand device.
+ */
+struct spinand_ondie_ecc_conf {
+	u8 status;
+};
+
 /**
  * struct spinand_info - Structure used to describe SPI NAND chips
  * @model: model name