[PATCH v8 3/5] mtd: rawnand: Write a compatibility layer

[Miquel Raynal <miquel.raynal@bootlin.com>]

Before moving generic bits from the raw NAND core to the generic NAND
core, let's disociate clearly what is a rawnand legacy property, and
what should be made public to other NAND users.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/nand/raw/nand_base.c | 158 +++++++++++++++++++++----------
 include/linux/mtd/rawnand.h      |  12 ---
 2 files changed, 107 insertions(+), 63 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index f120b0b4f591..8dc230892b90 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5029,14 +5029,6 @@ static int nand_detect(struct nand_chip *chip, struct nand_flash_dev *type)
 	return ret;
 }
 
-static const char * const nand_ecc_modes[] = {
-	[NAND_ECC_NONE]		= "none",
-	[NAND_ECC_SOFT]		= "soft",
-	[NAND_ECC_HW]		= "hw",
-	[NAND_ECC_HW_SYNDROME]	= "hw_syndrome",
-	[NAND_ECC_ON_DIE]	= "on-die",
-};
-
 static const char * const nand_ecc_placement[] = {
 	[NAND_ECC_PLACEMENT_OOB] = "oob",
 	[NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved",
@@ -5045,7 +5037,30 @@ static const char * const nand_ecc_placement[] = {
 static enum nand_ecc_engine_type
 of_get_nand_ecc_engine_type(struct device_node *np)
 {
-	enum nand_ecc_mode eng_type;
+	return NAND_ECC_ENGINE_TYPE_INVALID;
+}
+
+static enum nand_ecc_engine_type
+of_get_rawnand_ecc_engine_type_legacy(struct device_node *np)
+{
+	enum nand_ecc_legacy_mode {
+		NAND_ECC_INVALID,
+		NAND_ECC_NONE,
+		NAND_ECC_SOFT,
+		NAND_ECC_SOFT_BCH,
+		NAND_ECC_HW,
+		NAND_ECC_HW_SYNDROME,
+		NAND_ECC_ON_DIE,
+	};
+	const char * const nand_ecc_legacy_modes[] = {
+		[NAND_ECC_NONE]		= "none",
+		[NAND_ECC_SOFT]		= "soft",
+		[NAND_ECC_SOFT_BCH]	= "soft_bch",
+		[NAND_ECC_HW]		= "hw",
+		[NAND_ECC_HW_SYNDROME]	= "hw_syndrome",
+		[NAND_ECC_ON_DIE]	= "on-die",
+	};
+	enum nand_ecc_legacy_mode eng_type;
 	const char *pm;
 	int err;
 
@@ -5054,12 +5069,13 @@ of_get_nand_ecc_engine_type(struct device_node *np)
 		return NAND_ECC_ENGINE_TYPE_INVALID;
 
 	for (eng_type = NAND_ECC_NONE;
-	     eng_type < ARRAY_SIZE(nand_ecc_modes); eng_type++) {
-		if (!strcasecmp(pm, nand_ecc_modes[eng_type])) {
+	     eng_type < ARRAY_SIZE(nand_ecc_legacy_modes); eng_type++) {
+		if (!strcasecmp(pm, nand_ecc_legacy_modes[eng_type])) {
 			switch (eng_type) {
 			case NAND_ECC_NONE:
 				return NAND_ECC_ENGINE_TYPE_NONE;
 			case NAND_ECC_SOFT:
+			case NAND_ECC_SOFT_BCH:
 				return NAND_ECC_ENGINE_TYPE_SOFT;
 			case NAND_ECC_HW:
 			case NAND_ECC_HW_SYNDROME:
@@ -5072,14 +5088,6 @@ of_get_nand_ecc_engine_type(struct device_node *np)
 		}
 	}
 
-	/*
-	 * For backward compatibility we support few obsoleted values that don't
-	 * have their mappings into the nand_ecc_engine_providers enum anymore
-	 * (they were merged with other enums).
-	 */
-	if (!strcasecmp(pm, "soft_bch"))
-		return NAND_ECC_ENGINE_TYPE_SOFT;
-
 	return NAND_ECC_ENGINE_TYPE_INVALID;
 }
 
@@ -5091,17 +5099,22 @@ enum nand_ecc_placement of_get_nand_ecc_placement(struct device_node *np)
 
 	err = of_property_read_string(np, "nand-ecc-placement", &pm);
 	if (!err) {
-		for (placement = NAND_ECC_PLACEMENT_INTERLEAVED;
+		for (placement = NAND_ECC_PLACEMENT_OOB;
 		     placement < ARRAY_SIZE(nand_ecc_placement); placement++) {
 			if (!strcasecmp(pm, nand_ecc_placement[placement]))
 				return placement;
 		}
 	}
 
-	/*
-	 * For backward compatibility we support few obsoleted values that don't
-	 * have their mappings into the nand_ecc_placement enum anymore.
-	 */
+	return NAND_ECC_PLACEMENT_UNKNOWN;
+}
+
+enum nand_ecc_placement
+of_get_rawnand_ecc_placement_legacy(struct device_node *np)
+{
+	const char *pm;
+	int err;
+
 	err = of_property_read_string(np, "nand-ecc-mode", &pm);
 	if (!err) {
 		if (!strcasecmp(pm, "hw_syndrome"))
@@ -5133,10 +5146,14 @@ static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np)
 		}
 	}
 
-	/*
-	 * For backward compatibility we also read "nand-ecc-mode" checking
-	 * for some obsoleted values that were specifying ECC algorithm.
-	 */
+	return NAND_ECC_ALGO_UNKNOWN;
+}
+
+static enum nand_ecc_algo of_get_rawnand_ecc_algo_legacy(struct device_node *np)
+{
+	const char *pm;
+	int err;
+
 	err = of_property_read_string(np, "nand-ecc-mode", &pm);
 	if (!err) {
 		if (!strcasecmp(pm, "soft"))
@@ -5166,6 +5183,41 @@ static int of_get_nand_ecc_strength(struct device_node *np)
 	return ret ? ret : val;
 }
 
+static void nand_ecc_read_user_conf(struct nand_chip *chip)
+{
+	struct device_node *dn = nand_get_flash_node(chip);
+	struct nand_device *nand = &chip->base;
+	int strength, size;
+
+	nand->ecc.user_conf.engine_type = of_get_nand_ecc_engine_type(dn);
+	nand->ecc.user_conf.algo = of_get_nand_ecc_algo(dn);
+	nand->ecc.user_conf.placement = of_get_nand_ecc_placement(dn);
+
+	strength = of_get_nand_ecc_strength(dn);
+	if (strength >= 0)
+		nand->ecc.user_conf.strength = strength;
+
+	size = of_get_nand_ecc_step_size(dn);
+	if (size >= 0)
+		nand->ecc.user_conf.step_size = size;
+}
+
+static void rawnand_ecc_read_legacy_user_conf(struct nand_chip *chip)
+{
+	struct device_node *dn = nand_get_flash_node(chip);
+	struct nand_device *nand = &chip->base;
+	struct nand_ecc_props *user_conf = &nand->ecc.user_conf;
+
+	if (user_conf->engine_type != NAND_ECC_ENGINE_TYPE_INVALID)
+		user_conf->engine_type = of_get_rawnand_ecc_engine_type_legacy(dn);
+
+	if (user_conf->algo != NAND_ECC_ALGO_UNKNOWN)
+		user_conf->algo = of_get_rawnand_ecc_algo_legacy(dn);
+
+	if (user_conf->placement != NAND_ECC_PLACEMENT_UNKNOWN)
+		user_conf->placement = of_get_rawnand_ecc_placement_legacy(dn);
+}
+
 static int of_get_nand_bus_width(struct device_node *np)
 {
 	u32 val;
@@ -5187,12 +5239,10 @@ static bool of_get_nand_on_flash_bbt(struct device_node *np)
 	return of_property_read_bool(np, "nand-on-flash-bbt");
 }
 
-static int nand_dt_init(struct nand_chip *chip)
+static int rawnand_dt_init(struct nand_chip *chip)
 {
+	struct nand_device *nand = mtd_to_nanddev(nand_to_mtd(chip));
 	struct device_node *dn = nand_get_flash_node(chip);
-	enum nand_ecc_engine_type ecc_type;
-	enum nand_ecc_algo ecc_algo;
-	int ecc_strength, ecc_step;
 
 	if (!dn)
 		return 0;
@@ -5206,27 +5256,33 @@ static int nand_dt_init(struct nand_chip *chip)
 	if (of_get_nand_on_flash_bbt(dn))
 		chip->bbt_options |= NAND_BBT_USE_FLASH;
 
-	ecc_type = of_get_nand_ecc_engine_type(dn);
-	ecc_algo = of_get_nand_ecc_algo(dn);
-	chip->ecc.placement = of_get_nand_ecc_placement(dn);
-	ecc_strength = of_get_nand_ecc_strength(dn);
-	ecc_step = of_get_nand_ecc_step_size(dn);
-
-	if (ecc_type != NAND_ECC_ENGINE_TYPE_INVALID)
-		chip->ecc.engine_type = ecc_type;
-
-	if (ecc_algo != NAND_ECC_ALGO_UNKNOWN)
-		chip->ecc.algo = ecc_algo;
-
-	if (ecc_strength >= 0)
-		chip->ecc.strength = ecc_strength;
-
-	if (ecc_step > 0)
-		chip->ecc.size = ecc_step;
-
 	if (of_property_read_bool(dn, "nand-ecc-maximize"))
 		chip->ecc.options |= NAND_ECC_MAXIMIZE;
 
+	nand_ecc_read_user_conf(chip);
+	rawnand_ecc_read_legacy_user_conf(chip);
+
+	/*
+	 * If neither the user nor the NAND controller have requested a specific
+	 * ECC engine type, we will default to NAND_ECC_ENGINE_TYPE_ON_HOST.
+	 */
+	nand->ecc.defaults.engine_type = NAND_ECC_ENGINE_TYPE_ON_HOST;
+
+	/*
+	 * Use the user requested engine type, unless there is none, in this
+	 * case default to the NAND controller choice, otherwise fallback to
+	 * the raw NAND default one.
+	 */
+	if (nand->ecc.user_conf.engine_type != NAND_ECC_ENGINE_TYPE_INVALID)
+		chip->ecc.engine_type = nand->ecc.user_conf.engine_type;
+	if (chip->ecc.engine_type == NAND_ECC_ENGINE_TYPE_INVALID)
+		chip->ecc.engine_type = nand->ecc.defaults.engine_type;
+
+	chip->ecc.placement = nand->ecc.user_conf.placement;
+	chip->ecc.algo = nand->ecc.user_conf.algo;
+	chip->ecc.strength = nand->ecc.user_conf.strength;
+	chip->ecc.size = nand->ecc.user_conf.step_size;
+
 	return 0;
 }
 
@@ -5263,7 +5319,7 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips,
 	/* Enforce the right timings for reset/detection */
 	onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0);
 
-	ret = nand_dt_init(chip);
+	ret = rawnand_dt_init(chip);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index f3eb47c09e57..b455cb22168f 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -80,18 +80,6 @@ struct nand_chip;
 
 #define NAND_DATA_IFACE_CHECK_ONLY	-1
 
-/*
- * Constants for ECC_MODES
- */
-enum nand_ecc_mode {
-	NAND_ECC_INVALID,
-	NAND_ECC_NONE,
-	NAND_ECC_SOFT,
-	NAND_ECC_HW,
-	NAND_ECC_HW_SYNDROME,
-	NAND_ECC_ON_DIE,
-};
-
 /*
  * Constants for Hardware ECC
  */
-- 
2.20.1