[PATCH 2/3] mtd: spi-nor: Add Octal SPI support to Cadence QSPI driver.

[Artur Jedrysek]

Recent versions of Cadence QSPI controller support Octal SPI transfers
as well. This patch updates existing driver to support such feature.

It is not possible to determine whether or not octal mode is supported
just by looking at revision register alone. To solve that, an additional
property in Device Tree is added to indicate such capability.
Both (revision and DT property) are used to determine, which mode to
pass to spi_nor_scan() call.

Additionally, the driver works on Xtensa CPU, hence Kconfig update.

Signed-off-by: Artur Jedrysek <jartur at cadence.com>
---
 drivers/mtd/spi-nor/Kconfig           |  2 +-
 drivers/mtd/spi-nor/cadence-quadspi.c | 40 ++++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index 7252087..f195749 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -50,7 +50,7 @@ config SPI_ATMEL_QUADSPI
 
 config SPI_CADENCE_QUADSPI
 	tristate "Cadence Quad SPI controller"
-	depends on OF && (ARM || COMPILE_TEST)
+	depends on OF && (ARM || XTENSA || COMPILE_TEST)
 	help
 	  Enable support for the Cadence Quad SPI Flash controller.
 
diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index 9f8102d..5c06102 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -87,6 +87,7 @@ struct cqspi_st {
 #define CQSPI_INST_TYPE_SINGLE			0
 #define CQSPI_INST_TYPE_DUAL			1
 #define CQSPI_INST_TYPE_QUAD			2
+#define CQSPI_INST_TYPE_OCTAL			3
 
 #define CQSPI_DUMMY_CLKS_PER_BYTE		8
 #define CQSPI_DUMMY_BYTES_MAX			4
@@ -204,6 +205,14 @@ struct cqspi_st {
 #define CQSPI_REG_CMDWRITEDATALOWER		0xA8
 #define CQSPI_REG_CMDWRITEDATAUPPER		0xAC
 
+#define CQSPI_REG_MODULEID			0xFC
+#define CQSPI_REG_MODULEID_CONF_ID_MASK		0x3
+#define CQSPI_REG_MODULEID_CONF_ID_LSB		0
+#define CQSPI_REG_MODULEID_CONF_ID_OCTAL_PHY	0x0
+#define CQSPI_REG_MODULEID_CONF_ID_OCTAL	0x1
+#define CQSPI_REG_MODULEID_CONF_ID_QUAD_PHY	0x2
+#define CQSPI_REG_MODULEID_CONF_ID_QUAD		0x3
+
 /* Interrupt status bits */
 #define CQSPI_REG_IRQ_MODE_ERR			BIT(0)
 #define CQSPI_REG_IRQ_UNDERFLOW			BIT(1)
@@ -866,6 +875,9 @@ static int cqspi_set_protocol(struct spi_nor *nor, const int read)
 		case SPI_NOR_QUAD:
 			f_pdata->data_width = CQSPI_INST_TYPE_QUAD;
 			break;
+		case SPI_NOR_OCTAL:
+			f_pdata->data_width = CQSPI_INST_TYPE_OCTAL;
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -1074,9 +1086,35 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
 	struct cqspi_flash_pdata *f_pdata;
 	struct spi_nor *nor;
 	struct mtd_info *mtd;
+	enum read_mode mode;
+	enum read_mode dt_mode = SPI_NOR_QUAD;
 	unsigned int cs;
+	unsigned int rev_reg;
 	int i, ret;
 
+	/* Determine, whether or not octal transfer MAY be supported */
+	rev_reg = readl(cqspi->iobase + CQSPI_REG_MODULEID);
+	dev_info(dev, "CQSPI Module id %x\n", rev_reg);
+
+	switch (rev_reg & CQSPI_REG_MODULEID_CONF_ID_MASK) {
+	case CQSPI_REG_MODULEID_CONF_ID_OCTAL_PHY:
+	case CQSPI_REG_MODULEID_CONF_ID_OCTAL:
+		mode = SPI_NOR_OCTAL;
+		break;
+	case CQSPI_REG_MODULEID_CONF_ID_QUAD:
+	case CQSPI_REG_MODULEID_CONF_ID_QUAD_PHY:
+		mode = SPI_NOR_QUAD;
+		break;
+	}
+
+	if (of_property_read_bool(np, "cdns,octal-controller"))
+		dt_mode = SPI_NOR_OCTAL;
+
+	if (mode == SPI_NOR_QUAD && dt_mode == SPI_NOR_OCTAL)
+		dev_warn(dev, "Requested octal mode is not supported by the device.");
+	else if (mode == SPI_NOR_OCTAL && dt_mode == SPI_NOR_QUAD)
+		mode = SPI_NOR_QUAD;
+
 	/* Get flash device data */
 	for_each_available_child_of_node(dev->of_node, np) {
 		ret = of_property_read_u32(np, "reg", &cs);
@@ -1123,7 +1161,7 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
 			goto err;
 		}
 
-		ret = spi_nor_scan(nor, NULL, SPI_NOR_QUAD);
+		ret = spi_nor_scan(nor, NULL, mode);
 		if (ret)
 			goto err;
 
-- 
2.2.2