mtd: spi-nor: core: Introduce method for RDID op

RDID is used in the core to auto detect the flash, but also by some
manufacturer drivers that contain flashes that support Octal DTR mode,
so that they can read the flash ID after the switch to Octal DTR was made
to test if the switch was successful. Introduce a core method for RDID op
to avoid code duplication.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220420103427.47867-5-tudor.ambarus@microchip.com

drivers/mtd/spi-nor/core.c

@@ -369,6 +369,37 @@ int spi_nor_write_disable(struct spi_nor *nor)
 	return ret;
 }
 
+/**
+ * spi_nor_read_id() - Read the JEDEC ID.
+ * @nor:	pointer to 'struct spi_nor'.
+ * @naddr:	number of address bytes to send. Can be zero if the operation
+ *		does not need to send an address.
+ * @ndummy:	number of dummy bytes to send after an opcode or address. Can
+ *		be zero if the operation does not require dummy bytes.
+ * @id:		pointer to a DMA-able buffer where the value of the JEDEC ID
+ *		will be written.
+ * @proto:	the SPI protocol for register operation.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_read_id(struct spi_nor *nor, u8 naddr, u8 ndummy, u8 *id,
+		    enum spi_nor_protocol proto)
+{
+	int ret;
+
+	if (nor->spimem) {
+		struct spi_mem_op op =
+			SPI_NOR_READID_OP(naddr, ndummy, id, SPI_NOR_MAX_ID_LEN);
+
+		spi_nor_spimem_setup_op(nor, &op, proto);
+		ret = spi_mem_exec_op(nor->spimem, &op);
+	} else {
+		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDID, id,
+						    SPI_NOR_MAX_ID_LEN);
+	}
+	return ret;
+}
+
 /**
  * spi_nor_read_sr() - Read the Status Register.
  * @nor:	pointer to 'struct spi_nor'.
@@ -1658,24 +1689,13 @@ static const struct flash_info *spi_nor_match_id(struct spi_nor *nor,
 	return NULL;
 }
 
-static const struct flash_info *spi_nor_read_id(struct spi_nor *nor)
+static const struct flash_info *spi_nor_detect(struct spi_nor *nor)
 {
 	const struct flash_info *info;
 	u8 *id = nor->bouncebuf;
 	int ret;
 
-	if (nor->spimem) {
-		struct spi_mem_op op =
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDID, 1),
-				   SPI_MEM_OP_NO_ADDR,
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_IN(SPI_NOR_MAX_ID_LEN, id, 1));
-
-		ret = spi_mem_exec_op(nor->spimem, &op);
-	} else {
-		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDID, id,
-						    SPI_NOR_MAX_ID_LEN);
-	}
+	ret = spi_nor_read_id(nor, 0, 0, id, nor->reg_proto);
 	if (ret) {
 		dev_dbg(nor->dev, "error %d reading JEDEC ID\n", ret);
 		return ERR_PTR(ret);
@@ -2909,7 +2929,7 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
 		info = spi_nor_match_name(nor, name);
 	/* Try to auto-detect if chip name wasn't specified or not found */
 	if (!info)
-		return spi_nor_read_id(nor);
+		return spi_nor_detect(nor);
 
 	/*
 	 * If caller has specified name of flash model that can normally be
@@ -2918,7 +2938,7 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
 	if (name && info->id_len) {
 		const struct flash_info *jinfo;
 
-		jinfo = spi_nor_read_id(nor);
+		jinfo = spi_nor_detect(nor);
 		if (IS_ERR(jinfo)) {
 			return jinfo;
 		} else if (jinfo != info) {

drivers/mtd/spi-nor/core.h

@@ -11,6 +11,13 @@
 
 #define SPI_NOR_MAX_ID_LEN	6
 
+/* Standard SPI NOR flash operations. */
+#define SPI_NOR_READID_OP(naddr, ndummy, buf, len)			\
+	SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDID, 0),			\
+		   SPI_MEM_OP_ADDR(naddr, 0, 0),			\
+		   SPI_MEM_OP_DUMMY(ndummy, 0),				\
+		   SPI_MEM_OP_DATA_IN(len, buf, 0))
+
 enum spi_nor_option_flags {
 	SNOR_F_HAS_SR_TB	= BIT(0),
 	SNOR_F_NO_OP_CHIP_ERASE	= BIT(1),
@@ -534,6 +541,8 @@ void spi_nor_unlock_and_unprep(struct spi_nor *nor);
 int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor);
 int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor);
 int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor);
+int spi_nor_read_id(struct spi_nor *nor, u8 naddr, u8 ndummy, u8 *id,
+		    enum spi_nor_protocol reg_proto);
 int spi_nor_read_sr(struct spi_nor *nor, u8 *sr);
 int spi_nor_sr_ready(struct spi_nor *nor);
 int spi_nor_read_cr(struct spi_nor *nor, u8 *cr);