mtd: spi-nor: spansion: Rework spi_nor_cypress_octal_dtr_enable()

Introduce template operation to remove code duplication.
Split spi_nor_cypress_octal_dtr_enable() in
spi_nor_cypress_octal_dtr_ena() spi_nor_cypress_octal_dtr_dis() as it no
longer made sense to try to keep everything alltogether: too many
"if (enable)" throughout the code, which made the code difficult to read.
Add debug messages in case spi_nor_read_id() fails.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220420103427.47867-9-tudor.ambarus@microchip.com

Author: ambarus

drivers/mtd/spi-nor/spansion.c

@@ -23,94 +23,104 @@
 #define SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_DS	0
 #define SPINOR_OP_CYPRESS_RD_FAST		0xee
 
-/**
- * cypress_nor_octal_dtr_enable() - Enable octal DTR on Cypress flashes.
- * @nor:		pointer to a 'struct spi_nor'
- * @enable:              whether to enable or disable Octal DTR
- *
- * This also sets the memory access latency cycles to 24 to allow the flash to
- * run at up to 200MHz.
- *
- * Return: 0 on success, -errno otherwise.
- */
-static int cypress_nor_octal_dtr_enable(struct spi_nor *nor, bool enable)
+/* Cypress SPI NOR flash operations. */
+#define CYPRESS_NOR_WR_ANY_REG_OP(naddr, addr, ndata, buf)		\
+	SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_ANY_REG, 0),		\
+		   SPI_MEM_OP_ADDR(naddr, addr, 0),			\
+		   SPI_MEM_OP_NO_DUMMY,					\
+		   SPI_MEM_OP_DATA_OUT(ndata, buf, 0))
+
+static int cypress_nor_octal_dtr_en(struct spi_nor *nor)
 {
 	struct spi_mem_op op;
 	u8 *buf = nor->bouncebuf;
 	int ret;
 
-	if (enable) {
-		/* Use 24 dummy cycles for memory array reads. */
-		ret = spi_nor_write_enable(nor);
-		if (ret)
-			return ret;
+	/* Use 24 dummy cycles for memory array reads. */
+	*buf = SPINOR_REG_CYPRESS_CFR2V_MEMLAT_11_24;
+	op = (struct spi_mem_op)
+		CYPRESS_NOR_WR_ANY_REG_OP(3, SPINOR_REG_CYPRESS_CFR2V, 1, buf);
 
-		*buf = SPINOR_REG_CYPRESS_CFR2V_MEMLAT_11_24;
-		op = (struct spi_mem_op)
-			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_ANY_REG, 1),
-				   SPI_MEM_OP_ADDR(3, SPINOR_REG_CYPRESS_CFR2V,
-						   1),
-				   SPI_MEM_OP_NO_DUMMY,
-				   SPI_MEM_OP_DATA_OUT(1, buf, 1));
+	ret = spi_nor_write_any_volatile_reg(nor, &op, nor->reg_proto);
+	if (ret)
+		return ret;
 
-		ret = spi_mem_exec_op(nor->spimem, &op);
-		if (ret)
-			return ret;
+	ret = spi_nor_wait_till_ready(nor);
+	if (ret)
+		return ret;
 
-		ret = spi_nor_wait_till_ready(nor);
-		if (ret)
-			return ret;
+	nor->read_dummy = 24;
 
-		nor->read_dummy = 24;
-	}
+	/* Set the octal and DTR enable bits. */
+	buf[0] = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_EN;
+	op = (struct spi_mem_op)
+		CYPRESS_NOR_WR_ANY_REG_OP(3, SPINOR_REG_CYPRESS_CFR5V, 1, buf);
 
-	/* Set/unset the octal and DTR enable bits. */
-	ret = spi_nor_write_enable(nor);
+	ret = spi_nor_write_any_volatile_reg(nor, &op, nor->reg_proto);
 	if (ret)
 		return ret;
 
-	if (enable) {
-		buf[0] = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_EN;
-	} else {
-		/*
-		 * The register is 1-byte wide, but 1-byte transactions are not
-		 * allowed in 8D-8D-8D mode. Since there is no register at the
-		 * next location, just initialize the value to 0 and let the
-		 * transaction go on.
-		 */
-		buf[0] = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_DS;
-		buf[1] = 0;
+	/* Read flash ID to make sure the switch was successful. */
+	ret = spi_nor_read_id(nor, 4, 3, buf, SNOR_PROTO_8_8_8_DTR);
+	if (ret) {
+		dev_dbg(nor->dev, "error %d reading JEDEC ID after enabling 8D-8D-8D mode\n", ret);
+		return ret;
 	}
 
-	op = (struct spi_mem_op)
-		SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WR_ANY_REG, 1),
-			   SPI_MEM_OP_ADDR(enable ? 3 : 4,
-					   SPINOR_REG_CYPRESS_CFR5V,
-					   1),
-			   SPI_MEM_OP_NO_DUMMY,
-			   SPI_MEM_OP_DATA_OUT(enable ? 1 : 2, buf, 1));
+	if (memcmp(buf, nor->info->id, nor->info->id_len))
+		return -EINVAL;
 
-	if (!enable)
-		spi_nor_spimem_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
+	return 0;
+}
 
-	ret = spi_mem_exec_op(nor->spimem, &op);
+static int cypress_nor_octal_dtr_dis(struct spi_nor *nor)
+{
+	struct spi_mem_op op;
+	u8 *buf = nor->bouncebuf;
+	int ret;
+
+	/*
+	 * The register is 1-byte wide, but 1-byte transactions are not allowed
+	 * in 8D-8D-8D mode. Since there is no register at the next location,
+	 * just initialize the value to 0 and let the transaction go on.
+	 */
+	buf[0] = SPINOR_REG_CYPRESS_CFR5V_OCT_DTR_DS;
+	buf[1] = 0;
+	op = (struct spi_mem_op)
+		CYPRESS_NOR_WR_ANY_REG_OP(4, SPINOR_REG_CYPRESS_CFR5V, 2, buf);
+	ret = spi_nor_write_any_volatile_reg(nor, &op, SNOR_PROTO_8_8_8_DTR);
 	if (ret)
 		return ret;
 
 	/* Read flash ID to make sure the switch was successful. */
-	if (enable)
-		ret = spi_nor_read_id(nor, 4, 3, buf, SNOR_PROTO_8_8_8_DTR);
-	else
-		ret = spi_nor_read_id(nor, 0, 0, buf, SNOR_PROTO_1_1_1);
-	if (ret)
+	ret = spi_nor_read_id(nor, 0, 0, buf, SNOR_PROTO_1_1_1);
+	if (ret) {
+		dev_dbg(nor->dev, "error %d reading JEDEC ID after disabling 8D-8D-8D mode\n", ret);
 		return ret;
+	}
 
 	if (memcmp(buf, nor->info->id, nor->info->id_len))
 		return -EINVAL;
 
 	return 0;
 }
 
+/**
+ * cypress_nor_octal_dtr_enable() - Enable octal DTR on Cypress flashes.
+ * @nor:		pointer to a 'struct spi_nor'
+ * @enable:              whether to enable or disable Octal DTR
+ *
+ * This also sets the memory access latency cycles to 24 to allow the flash to
+ * run at up to 200MHz.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int cypress_nor_octal_dtr_enable(struct spi_nor *nor, bool enable)
+{
+	return enable ? cypress_nor_octal_dtr_en(nor) :
+			cypress_nor_octal_dtr_dis(nor);
+}
+
 static void s28hs512t_default_init(struct spi_nor *nor)
 {
 	nor->params->octal_dtr_enable = cypress_nor_octal_dtr_enable;