[PATCH 1/3] mtd: spi nor: add support for dual and quad bit transfers

[Jean Pihet]

Use the flags field of the SPI slave struct to pass the dual and quad
read properties, from the SPI NOR layer to the low level driver.
Tested with TI QSPI in 1, 2 and 4 bits modes.

Signed-off-by: Jean Pihet <jean.pihet at newoldbits.com>
---
 drivers/mtd/spi/spi-nor-core.c | 34 +++++++++++++++++++++++++++++++---
 drivers/spi/spi-mem.c          |  8 +++++++-
 include/spi.h                  |  2 ++
 3 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index e16b0e1462..54569b3cba 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -94,22 +94,50 @@ static ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
 	/* convert the dummy cycles to the number of bytes */
 	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
 
+	/* Check for dual and quad I/O read */
+	switch (op.cmd.opcode) {
+	case SPINOR_OP_READ_1_1_2:
+	case SPINOR_OP_READ_1_2_2:
+	case SPINOR_OP_READ_1_1_2_4B:
+	case SPINOR_OP_READ_1_2_2_4B:
+	case SPINOR_OP_READ_1_2_2_DTR:
+	case SPINOR_OP_READ_1_2_2_DTR_4B:
+		nor->spi->flags |= SPI_XFER_DUAL_READ;
+		break;
+	case SPINOR_OP_READ_1_1_4:
+	case SPINOR_OP_READ_1_4_4:
+	case SPINOR_OP_READ_1_1_4_4B:
+	case SPINOR_OP_READ_1_4_4_4B:
+	case SPINOR_OP_READ_1_4_4_DTR:
+	case SPINOR_OP_READ_1_4_4_DTR_4B:
+		nor->spi->flags |= SPI_XFER_QUAD_READ;
+		break;
+	default:
+		break;
+	}
+
 	while (remaining) {
 		op.data.nbytes = remaining < UINT_MAX ? remaining : UINT_MAX;
 		ret = spi_mem_adjust_op_size(nor->spi, &op);
 		if (ret)
-			return ret;
+			goto out;
 
 		ret = spi_mem_exec_op(nor->spi, &op);
 		if (ret)
-			return ret;
+			goto out;
 
 		op.addr.val += op.data.nbytes;
 		remaining -= op.data.nbytes;
 		op.data.buf.in += op.data.nbytes;
 	}
 
-	return len;
+	ret = len;
+
+out:
+	/* Reset dual and quad I/O read flags for upcoming transactions */
+	nor->spi->flags &= ~(SPI_XFER_DUAL_READ | SPI_XFER_QUAD_READ);
+
+	return ret;
 }
 
 static ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index c095ae9505..24e38ea95e 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -387,9 +387,15 @@ int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op)
 		return ret;
 
 	/* 2nd transfer: rx or tx data path */
+	flag = SPI_XFER_END;
+	/* Check for dual and quad I/O reads */
+	if (slave->flags & SPI_XFER_DUAL_READ)
+		flag |= SPI_XFER_DUAL_READ;
+	if (slave->flags & SPI_XFER_QUAD_READ)
+		flag |= SPI_XFER_QUAD_READ;
 	if (tx_buf || rx_buf) {
 		ret = spi_xfer(slave, op->data.nbytes * 8, tx_buf,
-			       rx_buf, SPI_XFER_END);
+			       rx_buf, flag);
 		if (ret)
 			return ret;
 	}
diff --git a/include/spi.h b/include/spi.h
index ef8c1f6692..cf5f05e526 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -146,6 +146,8 @@ struct spi_slave {
 #define SPI_XFER_BEGIN		BIT(0)	/* Assert CS before transfer */
 #define SPI_XFER_END		BIT(1)	/* Deassert CS after transfer */
 #define SPI_XFER_ONCE		(SPI_XFER_BEGIN | SPI_XFER_END)
+#define SPI_XFER_DUAL_READ	BIT(2)  /* Dual I/O read */
+#define SPI_XFER_QUAD_READ	BIT(3)  /* Quad I/O read */
 };
 
 /**
-- 
2.26.2