mtd: rawnand: loongson: Add 6-byte NAND ID reading support

Loongson-1C and Loongson-2K SoCs support NAND flash chips with 6-byte ID.
However, the current implementation only handles 5-byte ID which can lead
to incorrect chip detection.

Extend loongson_nand_read_id_type_exec() to support 6-byte NAND ID.

Signed-off-by: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: kelvincheung

drivers/mtd/nand/raw/loongson-nand-controller.c

@@ -50,6 +50,9 @@
 #define LOONGSON_NAND_COL_ADDR_CYC	2U
 #define LOONGSON_NAND_MAX_ADDR_CYC	5U
 
+#define LOONGSON_NAND_READ_ID_SLEEP_US		1000
+#define LOONGSON_NAND_READ_ID_TIMEOUT_US	5000
+
 #define BITS_PER_WORD			(4 * BITS_PER_BYTE)
 
 struct loongson_nand_host;
@@ -73,6 +76,8 @@ struct loongson_nand_op {
 };
 
 struct loongson_nand_data {
+	unsigned int max_id_cycle;
+	unsigned int id_cycle_field;
 	unsigned int status_field;
 	unsigned int op_scope_field;
 	unsigned int hold_cycle;
@@ -458,22 +463,27 @@ static int loongson_nand_read_id_type_exec(struct nand_chip *chip, const struct
 	struct loongson_nand_op op = {};
 	int i, ret;
 	union {
-		char ids[5];
+		char ids[6];
 		struct {
 			int idl;
-			char idh;
+			u16 idh;
 		};
 	} nand_id;
 
 	ret = loongson_nand_misc_type_exec(chip, subop, &op);
 	if (ret)
 		return ret;
 
-	nand_id.idl = readl(host->reg_base + LOONGSON_NAND_IDL);
-	nand_id.idh = readb(host->reg_base + LOONGSON_NAND_IDH_STATUS);
+	ret = regmap_read_poll_timeout(host->regmap, LOONGSON_NAND_IDL, nand_id.idl, nand_id.idl,
+				       LOONGSON_NAND_READ_ID_SLEEP_US,
+				       LOONGSON_NAND_READ_ID_TIMEOUT_US);
+	if (ret)
+		return ret;
 
-	for (i = 0; i < min(sizeof(nand_id.ids), op.orig_len); i++)
-		op.buf[i] = nand_id.ids[sizeof(nand_id.ids) - 1 - i];
+	nand_id.idh = readw(host->reg_base + LOONGSON_NAND_IDH_STATUS);
+
+	for (i = 0; i < min(host->data->max_id_cycle, op.orig_len); i++)
+		op.buf[i] = nand_id.ids[host->data->max_id_cycle - 1 - i];
 
 	return ret;
 }
@@ -676,6 +686,10 @@ static int loongson_nand_controller_init(struct loongson_nand_host *host)
 	if (IS_ERR(host->regmap))
 		return dev_err_probe(dev, PTR_ERR(host->regmap), "failed to init regmap\n");
 
+	if (host->data->id_cycle_field)
+		regmap_update_bits(host->regmap, LOONGSON_NAND_PARAM, host->data->id_cycle_field,
+				   host->data->max_id_cycle << __ffs(host->data->id_cycle_field));
+
 	chan = dma_request_chan(dev, "rxtx");
 	if (IS_ERR(chan))
 		return dev_err_probe(dev, PTR_ERR(chan), "failed to request DMA channel\n");
@@ -800,13 +814,16 @@ static void loongson_nand_remove(struct platform_device *pdev)
 }
 
 static const struct loongson_nand_data ls1b_nand_data = {
+	.max_id_cycle = 5,
 	.status_field = GENMASK(15, 8),
 	.hold_cycle = 0x2,
 	.wait_cycle = 0xc,
 	.set_addr = ls1b_nand_set_addr,
 };
 
 static const struct loongson_nand_data ls1c_nand_data = {
+	.max_id_cycle = 6,
+	.id_cycle_field = GENMASK(14, 12),
 	.status_field = GENMASK(23, 16),
 	.op_scope_field = GENMASK(29, 16),
 	.hold_cycle = 0x2,