[PATCH 0/2] Introduce Socionext F_OSPI SPI flash controller

[PATCH 0/2] Introduce Socionext F_OSPI SPI flash controller

[Kunihiko Hayashi]

This series adds dt-bindings and a driver for Socionext F_OSPI controller
for connecting an SPI Flash memory over up to 8-bit wide bus.
The controller supports up to 4 chip selects.

Kunihiko Hayashi (2):
  dt-bindings: spi: Add Socionext F_OSPI controller bindings
  spi: Add Socionext F_OSPI SPI flash controller driver

 .../bindings/spi/socionext,f-ospi.yaml        |  99 +++
 drivers/spi/Kconfig                           |   9 +
 drivers/spi/Makefile                          |   1 +
 drivers/spi/spi-sn-f-ospi.c                   | 818 ++++++++++++++++++
 4 files changed, 927 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml
 create mode 100644 drivers/spi/spi-sn-f-ospi.c

-- 
2.25.1

[PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Kunihiko Hayashi]

Add devicetree binding documentation for Socionext F_OSPI SPI flash
controller.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
 .../bindings/spi/socionext,f-ospi.yaml        | 99 +++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml

diff --git a/Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml b/Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml
new file mode 100644
index 000000000000..f52cac9ee9f8
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml
@@ -0,0 +1,99 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/spi/socionext,f-ospi.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Socionext F_OSPI controller
+
+description: |
+  The Socionext F_OSPI is a controller used to interface with flash
+  memories using the SPI communication interface.
+
+maintainers:
+  - Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
+
+allOf:
+  - $ref: "spi-controller.yaml#"
+
+properties:
+  compatible:
+    const: socionext,f-ospi
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  num-cs:
+    minimum: 1
+    maximum: 4
+
+  socionext,cs-start-cycle:
+    description:
+      Specifies the number of SPI_CLK cycles between CS assertion and
+      command transfer.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 15
+
+  socionext,cs-end-cycle:
+    description:
+      Specify the number of SPI_CLK cycles between data transfer and
+      CS deassertion.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 15
+
+  socionext,cs-deassert-clk-cycle:
+    description:
+      Specify the number of SPI_CLK cycles to output while CS is deasserted.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 15
+
+  socionext,alternative-byte:
+    description:
+      Specify the extra bytes to transfer after address transfer.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    items:
+      - description: the number of bytes to transfer
+        maximum: 4
+      - description: value to transfer
+        default: 0
+      - description: bit-width to transfer
+        enum: [0, 1, 2, 4, 8]
+
+  socionext,data-swap-2byte:
+    description:
+      Indicates swap byte order per 2-bytes.
+    type: boolean
+
+  socionext,data-swap-4byte:
+    description:
+      Indicates swap byte order per 4-bytes.
+    type: boolean
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - "#address-cells"
+  - "#size-cells"
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    ospi0: spi@80000000 {
+        compatible = "socionext,f-ospi";
+        reg = <0x80000000 0x1000>;
+        clocks = <&clks 0>;
+        num-cs = <1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+            compatible = "spansion,s25fl128s", "jedec,spi-nor";
+            reg = <0>;
+            spi-max-frequency = <50000000>;
+        };
+    };
-- 
2.25.1

[PATCH 2/2] spi: Add Socionext F_OSPI SPI flash controller driver

[Kunihiko Hayashi]

Introduce Socionext F_OSPI controller driver. This controller is used to
communicate with slave devices such as SPI Flash memories. It supports
4 slave devices and up to 8-bit wide bus, but supports master mode only.

This driver uses spi-mem framework for SPI flash memory access, and
can only operate indirect access mode and single data rate mode.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
 drivers/spi/Kconfig         |   9 +
 drivers/spi/Makefile        |   1 +
 drivers/spi/spi-sn-f-ospi.c | 818 ++++++++++++++++++++++++++++++++++++
 3 files changed, 828 insertions(+)
 create mode 100644 drivers/spi/spi-sn-f-ospi.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index cb7e3a8ef3a5..c6fb8cd6d2ae 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -906,6 +906,15 @@ config SPI_SLAVE_MT27XX
 	  say Y or M here.If you are not sure, say N.
 	  SPI slave drivers for Mediatek MT27XX series ARM SoCs.
 
+config SPI_SN_F_OSPI
+	tristate "Socionext F_OSPI SPI flash controller"
+	depends on OF && HAS_IOMEM
+	depends on SPI_MEM
+	help
+	  This enables support for the Socionext F_OSPI controller
+	  for connecting an SPI Flash memory over up to 8-bit wide bus.
+	  It supports indirect access mode only.
+
 config SPI_SPRD
 	tristate "Spreadtrum SPI controller"
 	depends on ARCH_SPRD || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 60d0b2f611f1..971bd62e4481 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -121,6 +121,7 @@ obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIFIVE)		+= spi-sifive.o
 obj-$(CONFIG_SPI_SLAVE_MT27XX)          += spi-slave-mt27xx.o
+obj-$(CONFIG_SPI_SN_F_OSPI)		+= spi-sn-f-ospi.o
 obj-$(CONFIG_SPI_SPRD)			+= spi-sprd.o
 obj-$(CONFIG_SPI_SPRD_ADI)		+= spi-sprd-adi.o
 obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
diff --git a/drivers/spi/spi-sn-f-ospi.c b/drivers/spi/spi-sn-f-ospi.c
new file mode 100644
index 000000000000..cd935fa86a6d
--- /dev/null
+++ b/drivers/spi/spi-sn-f-ospi.c
@@ -0,0 +1,818 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Socionext SPI flash controller F_OSPI driver
+ * Copyright (C) 2021 Socionext Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+
+/* Registers */
+#define OSPI_PROT_CTL_INDIR			0x00
+#define   OSPI_PROT_MODE_DATA_MASK		GENMASK(31, 30)
+#define   OSPI_PROT_MODE_ALT_MASK		GENMASK(29, 28)
+#define   OSPI_PROT_MODE_ADDR_MASK		GENMASK(27, 26)
+#define   OSPI_PROT_MODE_CODE_MASK		GENMASK(25, 24)
+#define     OSPI_PROT_MODE_SINGLE		0
+#define     OSPI_PROT_MODE_DUAL			1
+#define     OSPI_PROT_MODE_QUAD			2
+#define     OSPI_PROT_MODE_OCTAL		3
+#define   OSPI_PROT_DATA_RATE_DATA		BIT(23)
+#define   OSPI_PROT_DATA_RATE_ALT		BIT(22)
+#define   OSPI_PROT_DATA_RATE_ADDR		BIT(21)
+#define   OSPI_PROT_DATA_RATE_CODE		BIT(20)
+#define     OSPI_PROT_SDR			0
+#define     OSPI_PROT_DDR			1
+#define   OSPI_PROT_BIT_POS_DATA		BIT(19)
+#define   OSPI_PROT_BIT_POS_ALT			BIT(18)
+#define   OSPI_PROT_BIT_POS_ADDR		BIT(17)
+#define   OSPI_PROT_BIT_POS_CODE		BIT(16)
+#define   OSPI_PROT_SAMP_EDGE			BIT(12)
+#define   OSPI_PROT_DATA_UNIT_MASK		GENMASK(11, 10)
+#define     OSPI_PROT_DATA_UNIT_1B		0
+#define     OSPI_PROT_DATA_UNIT_2B		1
+#define     OSPI_PROT_DATA_UNIT_4B		3
+#define   OSPI_PROT_TRANS_DIR_WRITE		BIT(9)
+#define   OSPI_PROT_DATA_EN			BIT(8)
+#define   OSPI_PROT_ALT_SIZE_MASK		GENMASK(7, 5)
+#define   OSPI_PROT_ADDR_SIZE_MASK		GENMASK(4, 2)
+#define   OSPI_PROT_CODE_SIZE_MASK		GENMASK(1, 0)
+
+#define OSPI_CLK_CTL				0x10
+#define   OSPI_CLK_CTL_BOOT_INT_CLK_EN		BIT(16)
+#define   OSPI_CLK_CTL_PHA			BIT(12)
+#define     OSPI_CLK_CTL_PHA_180		0
+#define     OSPI_CLK_CTL_PHA_90			1
+#define   OSPI_CLK_CTL_DIV			GENMASK(9, 8)
+#define     OSPI_CLK_CTL_DIV_1			0
+#define     OSPI_CLK_CTL_DIV_2			1
+#define     OSPI_CLK_CTL_DIV_4			2
+#define     OSPI_CLK_CTL_DIV_8			3
+#define   OSPI_CLK_CTL_INT_CLK_EN		BIT(0)
+
+#define OSPI_CS_CTL1				0x14
+#define   OSPI_CS_CTL1_CS_START_MASK		GENMASK(7, 4)
+#define   OSPI_CS_CTL1_CS_END_MASK		GENMASK(3, 0)
+
+#define OSPI_CS_CTL2				0x18
+#define   OSPI_CS_CTL2_CS_DESEL_CYC_MASK	GENMASK(7, 4)
+#define   OSPI_CS_CTL2_CS_DESEL_EN		BIT(0)
+
+#define OSPI_SSEL				0x20
+#define OSPI_CMD_IDX_INDIR			0x40
+#define OSPI_ADDR				0x50
+#define OSPI_ALT_INDIR				0x60
+#define OSPI_DMY_INDIR				0x70
+#define OSPI_DAT				0x80
+#define OSPI_DAT_SWP_INDIR			0x90
+#define   OSPI_DAT_SWP_EN			BIT(8)
+#define   OSPI_DAT_SWP_4TH_BYTE			GENMASK(7, 6)
+#define   OSPI_DAT_SWP_3RD_BYTE			GENMASK(5, 4)
+#define   OSPI_DAT_SWP_2ND_BYTE			GENMASK(3, 2)
+#define   OSPI_DAT_SWP_1ST_BYTE			GENMASK(1, 0)
+
+#define OSPI_DAT_SIZE_INDIR			0xA0
+#define   OSPI_DAT_SIZE_EN			BIT(15)
+#define   OSPI_DAT_SIZE_MASK			GENMASK(10, 0)
+#define   OSPI_DAT_SIZE_MAX			(OSPI_DAT_SIZE_MASK + 1)
+
+#define OSPI_TRANS_CTL				0xC0
+#define   OSPI_TRANS_CTL_STOP_REQ		BIT(1)	/* RW1AC */
+#define   OSPI_TRANS_CTL_START_REQ		BIT(0)	/* RW1AC */
+
+#define OSPI_ACC_MODE				0xC4
+#define   OSPI_ACC_MODE_BOOT_DISABLE		BIT(0)
+
+#define OSPI_SWRST				0xD0
+#define   OSPI_SWRST_INDIR_WRITE_FIFO		BIT(9)	/* RW1AC */
+#define   OSPI_SWRST_INDIR_READ_FIFO		BIT(8)	/* RW1AC */
+
+#define OSPI_STAT				0xE0
+#define   OSPI_STAT_IS_AXI_WRITING		BIT(10)
+#define   OSPI_STAT_IS_AXI_READING		BIT(9)
+#define   OSPI_STAT_IS_SPI_INT_CLK_STOP		BIT(4)
+#define   OSPI_STAT_IS_SPI_IDLE			BIT(3)
+
+#define OSPI_IRQ				0xF0
+#define   OSPI_IRQ_CS_DEASSERT			BIT(8)
+#define   OSPI_IRQ_WRITE_BUF_READY		BIT(2)
+#define   OSPI_IRQ_READ_BUF_READY		BIT(1)
+#define   OSPI_IRQ_CS_TRANS_COMP		BIT(0)
+#define   OSPI_IRQ_ALL				\
+		(OSPI_IRQ_CS_DEASSERT | OSPI_IRQ_WRITE_BUF_READY \
+		 | OSPI_IRQ_READ_BUF_READY | OSPI_IRQ_CS_TRANS_COMP)
+
+#define OSPI_IRQ_STAT_EN			0xF4
+#define OSPI_IRQ_SIG_EN				0xF8
+
+/* Parameters */
+#define OSPI_NUM_CS				4
+#define OSPI_DUMMY_CYCLE_MAX			255
+#define OSPI_WAIT_MAX_MSEC			100
+
+enum f_ospi_swap_mode {
+	OSPI_SWAP_MODE_NONE = 0,
+	OSPI_SWAP_MODE_2BYTE,
+	OSPI_SWAP_MODE_4BYTE,
+};
+
+struct f_ospi {
+	struct mutex mlock;
+	void __iomem *base;
+	struct device *dev;
+	struct clk *clk;
+
+	u8 cs_cyc_start;
+	u8 cs_cyc_end;
+	u8 cs_cyc_deassert;
+	bool cs_cyc_deassert_en;
+
+	struct {
+		u8 nbytes;
+		u8 buswidth;
+		u32 val;
+	} alt;
+
+	enum f_ospi_swap_mode swap_mode;
+};
+
+static u32 f_ospi_get_dummy_cycle(const struct spi_mem_op *op)
+{
+	return (op->dummy.nbytes * 8) / op->dummy.buswidth;
+}
+
+static void f_ospi_clear_irq(struct f_ospi *ospi)
+{
+	writel(OSPI_IRQ_CS_DEASSERT | OSPI_IRQ_CS_TRANS_COMP,
+	       ospi->base + OSPI_IRQ);
+}
+
+static void f_ospi_enable_irq_status(struct f_ospi *ospi, u32 irq_bits)
+{
+	u32 val;
+
+	val = readl(ospi->base + OSPI_IRQ_STAT_EN);
+	val |= irq_bits;
+	writel(val, ospi->base + OSPI_IRQ_STAT_EN);
+}
+
+static void f_ospi_disable_irq_status(struct f_ospi *ospi, u32 irq_bits)
+{
+	u32 val;
+
+	val = readl(ospi->base + OSPI_IRQ_STAT_EN);
+	val &= ~irq_bits;
+	writel(val, ospi->base + OSPI_IRQ_STAT_EN);
+}
+
+static void f_ospi_disable_irq_output(struct f_ospi *ospi, u32 irq_bits)
+{
+	u32 val;
+
+	val = readl(ospi->base + OSPI_IRQ_SIG_EN);
+	val &= ~irq_bits;
+	writel(val, ospi->base + OSPI_IRQ_SIG_EN);
+}
+
+static int f_ospi_prepare_config(struct f_ospi *ospi)
+{
+	u32 val, stat0, stat1;
+
+	/* G4: Disable internal clock */
+	val = readl(ospi->base + OSPI_CLK_CTL);
+	val &= ~(OSPI_CLK_CTL_BOOT_INT_CLK_EN | OSPI_CLK_CTL_INT_CLK_EN);
+	writel(val, ospi->base + OSPI_CLK_CTL);
+
+	/* G5: Wait for stop */
+	stat0 = OSPI_STAT_IS_AXI_WRITING | OSPI_STAT_IS_AXI_READING;
+	stat1 = OSPI_STAT_IS_SPI_IDLE | OSPI_STAT_IS_SPI_INT_CLK_STOP;
+
+	return readl_poll_timeout(ospi->base + OSPI_STAT,
+				  val, (val & (stat0 | stat1)) == stat1,
+				  0, OSPI_WAIT_MAX_MSEC);
+}
+
+static int f_ospi_unprepare_config(struct f_ospi *ospi)
+{
+	u32 val;
+
+	/* G11: Enable internal clock */
+	val = readl(ospi->base + OSPI_CLK_CTL);
+	val |= OSPI_CLK_CTL_BOOT_INT_CLK_EN | OSPI_CLK_CTL_INT_CLK_EN;
+	writel(val, ospi->base + OSPI_CLK_CTL);
+
+	/* G12: Wait for clock to start */
+	return readl_poll_timeout(ospi->base + OSPI_STAT,
+				  val, !(val & OSPI_STAT_IS_SPI_INT_CLK_STOP),
+				  0, OSPI_WAIT_MAX_MSEC);
+}
+
+static void f_ospi_config_clk(struct f_ospi *ospi, u32 device_hz)
+{
+	long rate_hz = clk_get_rate(ospi->clk);
+	u32 div = DIV_ROUND_UP(rate_hz, device_hz);
+	u32 div_reg;
+	u32 val;
+
+	if (rate_hz < device_hz) {
+		dev_warn(ospi->dev, "Device frequency too large: %d\n",
+			 device_hz);
+		div_reg = OSPI_CLK_CTL_DIV_1;
+	} else {
+		if (div == 1) {
+			div_reg = OSPI_CLK_CTL_DIV_1;
+		} else if (div == 2) {
+			div_reg = OSPI_CLK_CTL_DIV_2;
+		} else if (div <= 4) {
+			div_reg = OSPI_CLK_CTL_DIV_4;
+		} else if (div <= 8) {
+			div_reg = OSPI_CLK_CTL_DIV_8;
+		} else {
+			dev_warn(ospi->dev, "Device frequency too small: %d\n",
+				 device_hz);
+			div_reg = OSPI_CLK_CTL_DIV_8;
+		}
+	}
+
+	/*
+	 * G7: Set clock mode
+	 * clock phase is fixed at 180 degrees and configure edge direction
+	 * instead.
+	 */
+	val = readl(ospi->base + OSPI_CLK_CTL);
+
+	val &= ~(OSPI_CLK_CTL_PHA | OSPI_CLK_CTL_DIV);
+	val |= FIELD_PREP(OSPI_CLK_CTL_PHA, OSPI_CLK_CTL_PHA_180)
+	     | FIELD_PREP(OSPI_CLK_CTL_DIV, div_reg);
+
+	writel(val, ospi->base + OSPI_CLK_CTL);
+}
+
+static void f_ospi_config_dll(struct f_ospi *ospi)
+{
+	/* G8: Configure DLL, nothing */
+}
+
+static u8 f_ospi_get_mode(struct f_ospi *ospi, int width, int data_size)
+{
+	u8 mode = OSPI_PROT_MODE_SINGLE;
+
+	switch (width) {
+	case 1:
+		mode = OSPI_PROT_MODE_SINGLE;
+		break;
+	case 2:
+		mode = OSPI_PROT_MODE_DUAL;
+		break;
+	case 4:
+		mode = OSPI_PROT_MODE_QUAD;
+		break;
+	case 8:
+		mode = OSPI_PROT_MODE_OCTAL;
+		break;
+	default:
+		if (data_size)
+			dev_err(ospi->dev, "Invalid buswidth: %d\n", width);
+		break;
+	}
+
+	return mode;
+}
+
+static void f_ospi_config_indir_protocol(struct f_ospi *ospi,
+					 struct spi_mem *mem,
+					 const struct spi_mem_op *op)
+{
+	struct spi_device *spi = mem->spi;
+	u8 mode;
+	u32 prot = 0, val;
+	int unit;
+
+	/* Set one chip select */
+	writel(BIT(spi->chip_select), ospi->base + OSPI_SSEL);
+
+	mode = f_ospi_get_mode(ospi, op->cmd.buswidth, 1);
+	prot |= FIELD_PREP(OSPI_PROT_MODE_CODE_MASK, mode);
+
+	mode = f_ospi_get_mode(ospi, op->addr.buswidth, op->addr.nbytes);
+	prot |= FIELD_PREP(OSPI_PROT_MODE_ADDR_MASK, mode);
+
+	mode = f_ospi_get_mode(ospi, op->data.buswidth, op->data.nbytes);
+	prot |= FIELD_PREP(OSPI_PROT_MODE_DATA_MASK, mode);
+
+	mode = f_ospi_get_mode(ospi, ospi->alt.buswidth, ospi->alt.nbytes);
+	prot |= FIELD_PREP(OSPI_PROT_MODE_ALT_MASK, mode);
+
+	prot |= FIELD_PREP(OSPI_PROT_DATA_RATE_DATA, OSPI_PROT_SDR);
+	prot |= FIELD_PREP(OSPI_PROT_DATA_RATE_ALT,  OSPI_PROT_SDR);
+	prot |= FIELD_PREP(OSPI_PROT_DATA_RATE_ADDR, OSPI_PROT_SDR);
+	prot |= FIELD_PREP(OSPI_PROT_DATA_RATE_CODE, OSPI_PROT_SDR);
+
+	if (spi->mode & SPI_LSB_FIRST)
+		prot |= OSPI_PROT_BIT_POS_DATA | OSPI_PROT_BIT_POS_ALT
+		      | OSPI_PROT_BIT_POS_ADDR | OSPI_PROT_BIT_POS_CODE;
+
+	if (spi->mode & SPI_CPHA)
+		prot |= OSPI_PROT_SAMP_EDGE;
+
+	/* Examine nbytes % 4 */
+	switch (op->data.nbytes & 0x3) {
+	case 0:
+		unit = OSPI_PROT_DATA_UNIT_4B;
+		val = 0;
+		break;
+	case 2:
+		unit = OSPI_PROT_DATA_UNIT_2B;
+		val = OSPI_DAT_SIZE_EN | (op->data.nbytes - 1);
+		break;
+	default:
+		unit = OSPI_PROT_DATA_UNIT_1B;
+		val = OSPI_DAT_SIZE_EN | (op->data.nbytes - 1);
+		break;
+	}
+	prot |= FIELD_PREP(OSPI_PROT_DATA_UNIT_MASK, unit);
+
+	switch (op->data.dir) {
+	case SPI_MEM_DATA_IN:
+		prot |= OSPI_PROT_DATA_EN;
+		break;
+
+	case SPI_MEM_DATA_OUT:
+		prot |= OSPI_PROT_TRANS_DIR_WRITE | OSPI_PROT_DATA_EN;
+		break;
+
+	case SPI_MEM_NO_DATA:
+		prot |= OSPI_PROT_TRANS_DIR_WRITE;
+		break;
+
+	default:
+		dev_warn(ospi->dev, "Unsupported direction");
+		break;
+	}
+
+	prot |= FIELD_PREP(OSPI_PROT_ALT_SIZE_MASK, ospi->alt.nbytes);
+	prot |= FIELD_PREP(OSPI_PROT_ADDR_SIZE_MASK, op->addr.nbytes);
+	prot |= FIELD_PREP(OSPI_PROT_CODE_SIZE_MASK, 1);	/* 1byte */
+
+	writel(prot, ospi->base + OSPI_PROT_CTL_INDIR);
+	writel(val, ospi->base + OSPI_DAT_SIZE_INDIR);
+}
+
+static int f_ospi_indir_prepare_op(struct f_ospi *ospi, struct spi_mem *mem,
+				   const struct spi_mem_op *op)
+{
+	struct spi_device *spi = mem->spi;
+	u32 irq_stat_en;
+	int ret;
+
+	ret = f_ospi_prepare_config(ospi);
+	if (ret)
+		return ret;
+
+	f_ospi_config_clk(ospi, spi->max_speed_hz);
+
+	f_ospi_config_indir_protocol(ospi, mem, op);
+
+	writel(f_ospi_get_dummy_cycle(op), ospi->base + OSPI_DMY_INDIR);
+	writel(op->addr.val, ospi->base + OSPI_ADDR);
+	writel(op->cmd.opcode, ospi->base + OSPI_CMD_IDX_INDIR);
+
+	f_ospi_clear_irq(ospi);
+
+	switch (op->data.dir) {
+	case SPI_MEM_DATA_IN:
+		irq_stat_en = OSPI_IRQ_READ_BUF_READY | OSPI_IRQ_CS_TRANS_COMP;
+		break;
+
+	case SPI_MEM_DATA_OUT:
+		irq_stat_en = OSPI_IRQ_WRITE_BUF_READY | OSPI_IRQ_CS_TRANS_COMP;
+		break;
+
+	case SPI_MEM_NO_DATA:
+		irq_stat_en = OSPI_IRQ_CS_TRANS_COMP;
+		break;
+
+	default:
+		dev_warn(ospi->dev, "Unsupported direction");
+		irq_stat_en = 0;
+	}
+
+	f_ospi_disable_irq_status(ospi, ~irq_stat_en);
+	f_ospi_enable_irq_status(ospi, irq_stat_en);
+
+	return f_ospi_unprepare_config(ospi);
+}
+
+static void f_ospi_indir_start_xfer(struct f_ospi *ospi)
+{
+	/* Write only 1, auto cleared */
+	writel(OSPI_TRANS_CTL_START_REQ, ospi->base + OSPI_TRANS_CTL);
+}
+
+static void f_ospi_indir_stop_xfer(struct f_ospi *ospi)
+{
+	/* Write only 1, auto cleared */
+	writel(OSPI_TRANS_CTL_STOP_REQ, ospi->base + OSPI_TRANS_CTL);
+}
+
+static int f_ospi_indir_wait_xfer_complete(struct f_ospi *ospi)
+{
+	u32 val;
+
+	return readl_poll_timeout(ospi->base + OSPI_IRQ, val,
+				  val & OSPI_IRQ_CS_TRANS_COMP,
+				  0, OSPI_WAIT_MAX_MSEC);
+}
+
+static int f_ospi_indir_read(struct f_ospi *ospi, struct spi_mem *mem,
+			     const struct spi_mem_op *op)
+{
+	u8 *buf = op->data.buf.in;
+	u32 val;
+	int i, ret;
+
+	mutex_lock(&ospi->mlock);
+
+	/* E1-2: Prepare transfer operation */
+	ret = f_ospi_indir_prepare_op(ospi, mem, op);
+	if (ret)
+		goto out;
+
+	f_ospi_indir_start_xfer(ospi);
+
+	/* E3-4: Wait for ready and read data */
+	for (i = 0; i < op->data.nbytes; i++) {
+		ret = readl_poll_timeout(ospi->base + OSPI_IRQ, val,
+					 val & OSPI_IRQ_READ_BUF_READY,
+					 0, OSPI_WAIT_MAX_MSEC);
+		if (ret)
+			goto out;
+
+		buf[i] = readl(ospi->base + OSPI_DAT) & 0xFF;
+	}
+
+	/* E5-6: Stop transfer if data size is nothing */
+	if (!(readl(ospi->base + OSPI_DAT_SIZE_INDIR) & OSPI_DAT_SIZE_EN))
+		f_ospi_indir_stop_xfer(ospi);
+
+	/* E7-8: Wait for completion and clear */
+	ret = f_ospi_indir_wait_xfer_complete(ospi);
+	if (ret)
+		goto out;
+
+	writel(OSPI_IRQ_CS_TRANS_COMP, ospi->base + OSPI_IRQ);
+
+	/* E9: Do nothing if data size is valid */
+	if (readl(ospi->base + OSPI_DAT_SIZE_INDIR) & OSPI_DAT_SIZE_EN)
+		goto out;
+
+	/* E10-11: Reset and check read fifo */
+	writel(OSPI_SWRST_INDIR_READ_FIFO, ospi->base + OSPI_SWRST);
+
+	ret = readl_poll_timeout(ospi->base + OSPI_SWRST, val,
+				 !(val & OSPI_SWRST_INDIR_READ_FIFO),
+				 0, OSPI_WAIT_MAX_MSEC);
+out:
+	mutex_unlock(&ospi->mlock);
+
+	return ret;
+}
+
+static int f_ospi_indir_write(struct f_ospi *ospi, struct spi_mem *mem,
+			      const struct spi_mem_op *op)
+{
+	u8 *buf = (u8 *)op->data.buf.out;
+	u32 val;
+	int i, ret;
+
+	mutex_lock(&ospi->mlock);
+
+	/* F1-3: Prepare transfer operation */
+	ret = f_ospi_indir_prepare_op(ospi, mem, op);
+	if (ret)
+		goto out;
+
+	f_ospi_indir_start_xfer(ospi);
+
+	if (!(readl(ospi->base + OSPI_PROT_CTL_INDIR) & OSPI_PROT_DATA_EN))
+		goto nodata;
+
+	/* F4-5: Wait for buffer ready and write data */
+	for (i = 0; i < op->data.nbytes; i++) {
+		ret = readl_poll_timeout(ospi->base + OSPI_IRQ, val,
+					 val & OSPI_IRQ_WRITE_BUF_READY,
+					 0, OSPI_WAIT_MAX_MSEC);
+		if (ret)
+			goto out;
+
+		writel(buf[i], ospi->base + OSPI_DAT);
+	}
+
+	/* F6-7: Stop transfer if data size is nothing */
+	if (!(readl(ospi->base + OSPI_DAT_SIZE_INDIR) & OSPI_DAT_SIZE_EN))
+		f_ospi_indir_stop_xfer(ospi);
+
+nodata:
+	/* F8-9: Wait for completion and clear */
+	ret = f_ospi_indir_wait_xfer_complete(ospi);
+	if (ret)
+		goto out;
+
+	writel(OSPI_IRQ_CS_TRANS_COMP, ospi->base + OSPI_IRQ);
+out:
+	mutex_unlock(&ospi->mlock);
+
+	return ret;
+}
+
+static int f_ospi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+	struct f_ospi *ospi = spi_controller_get_devdata(mem->spi->master);
+	int err = 0;
+
+	switch (op->data.dir) {
+	case SPI_MEM_DATA_IN:
+		err = f_ospi_indir_read(ospi, mem, op);
+		break;
+
+	case SPI_MEM_DATA_OUT:
+		fallthrough;
+	case SPI_MEM_NO_DATA:
+		err = f_ospi_indir_write(ospi, mem, op);
+		break;
+
+	default:
+		dev_warn(ospi->dev, "Unsupported direction");
+		err = -EOPNOTSUPP;
+	}
+
+	return err;
+}
+
+static bool f_ospi_supports_op_width(struct spi_mem *mem,
+				     const struct spi_mem_op *op)
+{
+	u8 width_available[] = { 0, 1, 2, 4, 8 };
+	u8 width_op[] = { op->cmd.buswidth, op->addr.buswidth,
+			  op->dummy.buswidth, op->data.buswidth };
+	bool is_match_found;
+	int i, j;
+
+	for (i = 0; i < ARRAY_SIZE(width_op); i++) {
+		is_match_found = false;
+
+		for (j = 0; j < ARRAY_SIZE(width_available); j++) {
+			if (width_op[i] == width_available[j]) {
+				is_match_found = true;
+				break;
+			}
+		}
+
+		if (!is_match_found)
+			return false;
+	}
+
+	return true;
+}
+
+static bool f_ospi_supports_op(struct spi_mem *mem,
+			       const struct spi_mem_op *op)
+{
+	if (f_ospi_get_dummy_cycle(op) > OSPI_DUMMY_CYCLE_MAX)
+		return false;
+
+	if (op->addr.nbytes > 5)
+		return false;
+
+	if (!f_ospi_supports_op_width(mem, op))
+		return false;
+
+	return true;
+}
+
+static int f_ospi_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
+	op->data.nbytes = min((int)op->data.nbytes, (int)(OSPI_DAT_SIZE_MAX));
+
+	return 0;
+}
+
+static const struct spi_controller_mem_ops f_ospi_mem_ops = {
+	.adjust_op_size = f_ospi_adjust_op_size,
+	.supports_op = f_ospi_supports_op,
+	.exec_op = f_ospi_exec_op,
+};
+
+static int f_ospi_init(struct f_ospi *ospi)
+{
+	u32 val;
+	int ret;
+
+	ret = f_ospi_prepare_config(ospi);
+	if (ret)
+		return ret;
+
+	/* Disable boot signal */
+	writel(OSPI_ACC_MODE_BOOT_DISABLE, ospi->base + OSPI_ACC_MODE);
+
+	f_ospi_config_dll(ospi);
+
+	/* Configure DT-derived parameters */
+	writel(FIELD_PREP(OSPI_CS_CTL1_CS_START_MASK, ospi->cs_cyc_start)
+	       | FIELD_PREP(OSPI_CS_CTL1_CS_END_MASK, ospi->cs_cyc_end),
+	       ospi->base + OSPI_CS_CTL1);
+
+	val = FIELD_PREP(OSPI_CS_CTL2_CS_DESEL_CYC_MASK, ospi->cs_cyc_deassert)
+		| OSPI_CS_CTL2_CS_DESEL_EN;
+	writel(ospi->cs_cyc_deassert_en ? val : 0, ospi->base + OSPI_CS_CTL2);
+
+	writel(ospi->alt.val, ospi->base + OSPI_ALT_INDIR);
+
+	/* Set data byte order */
+	switch (ospi->swap_mode) {
+	case OSPI_SWAP_MODE_4BYTE:
+		val = OSPI_DAT_SWP_EN
+			| FIELD_PREP(OSPI_DAT_SWP_4TH_BYTE, 3)
+			| FIELD_PREP(OSPI_DAT_SWP_3RD_BYTE, 2)
+			| FIELD_PREP(OSPI_DAT_SWP_2ND_BYTE, 1)
+			| FIELD_PREP(OSPI_DAT_SWP_1ST_BYTE, 0);
+		break;
+	case OSPI_SWAP_MODE_2BYTE:
+		val = OSPI_DAT_SWP_EN
+			| FIELD_PREP(OSPI_DAT_SWP_4TH_BYTE, 1)
+			| FIELD_PREP(OSPI_DAT_SWP_3RD_BYTE, 0)
+			| FIELD_PREP(OSPI_DAT_SWP_2ND_BYTE, 3)
+			| FIELD_PREP(OSPI_DAT_SWP_1ST_BYTE, 2);
+		break;
+	default:
+		val = 0;
+		break;
+	}
+	writel(val, ospi->base + OSPI_DAT_SWP_INDIR);
+
+	/* Disable IRQ */
+	f_ospi_clear_irq(ospi);
+	f_ospi_disable_irq_status(ospi, OSPI_IRQ_ALL);
+	f_ospi_disable_irq_output(ospi, OSPI_IRQ_ALL);
+
+	return f_ospi_unprepare_config(ospi);
+}
+
+static void f_ospi_parse_dt(struct f_ospi *ospi, struct device_node *node)
+{
+	u32 alt[4];
+	u32 val;
+
+	if (!of_property_read_u32(node, "socionext,cs-start-cycle", &val))
+		ospi->cs_cyc_start = val;
+
+	if (!of_property_read_u32(node, "socionext,cs-end-cycle", &val))
+		ospi->cs_cyc_end = val;
+
+	if (!of_property_read_u32(node, "socionext,cs-deassert-clk-cycle",
+				  &val)) {
+		ospi->cs_cyc_deassert_en = true;
+		ospi->cs_cyc_deassert = val;
+
+		if (ospi->cs_cyc_deassert > 15) {
+			dev_warn(ospi->dev, "cs-deassert-clk-cycle too large: %d\n",
+				 ospi->cs_cyc_deassert);
+			ospi->cs_cyc_deassert = 0;	/* infinite */
+		}
+	}
+
+	if (!of_property_read_u32_array(node, "socionext,alternative-byte",
+					alt, 3)) {
+		ospi->alt.nbytes = alt[0];
+		ospi->alt.val = alt[1];
+		ospi->alt.buswidth = alt[2];
+
+		if (ospi->alt.nbytes > 4) {
+			dev_warn(ospi->dev,
+				 "alternative-byte size too large: %d\n",
+				 ospi->alt.nbytes);
+			ospi->alt.nbytes = 4;
+		}
+	}
+
+	if (of_property_read_bool(node, "socionext,data-swap-2byte"))
+		ospi->swap_mode = OSPI_SWAP_MODE_2BYTE;
+	else if (of_property_read_bool(node, "socionext,data-swap-4byte"))
+		ospi->swap_mode = OSPI_SWAP_MODE_4BYTE;
+	else
+		ospi->swap_mode = OSPI_SWAP_MODE_NONE;
+}
+
+static int f_ospi_probe(struct platform_device *pdev)
+{
+	struct spi_controller *ctlr;
+	struct device *dev = &pdev->dev;
+	struct f_ospi *ospi;
+	u32 num_cs = OSPI_NUM_CS;
+	int ret;
+
+	ctlr = spi_alloc_master(dev, sizeof(*ospi));
+	if (!ctlr)
+		return -ENOMEM;
+
+	ctlr->mode_bits = SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL
+		| SPI_RX_DUAL | SPI_RX_QUAD | SPI_TX_OCTAL
+		| SPI_MODE_0 | SPI_MODE_1 | SPI_LSB_FIRST;
+	ctlr->mem_ops = &f_ospi_mem_ops;
+	ctlr->bus_num = -1;
+	of_property_read_u32(dev->of_node, "num-cs", &num_cs);
+	if (num_cs > OSPI_NUM_CS) {
+		dev_err(dev, "num-cs too large: %d\n", num_cs);
+		return -ENOMEM;
+	}
+	ctlr->num_chipselect = num_cs;
+	ctlr->dev.of_node = dev->of_node;
+
+	ospi = spi_controller_get_devdata(ctlr);
+	ospi->dev = dev;
+
+	f_ospi_parse_dt(ospi, dev->of_node);
+
+	platform_set_drvdata(pdev, ospi);
+
+	ospi->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ospi->base)) {
+		ret = PTR_ERR(ospi->base);
+		goto err_put_ctlr;
+	}
+
+	ospi->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ospi->clk)) {
+		ret = PTR_ERR(ospi->clk);
+		goto err_put_ctlr;
+	}
+
+	ret = clk_prepare_enable(ospi->clk);
+	if (ret) {
+		dev_err(dev, "Failed to enable the clock\n");
+		goto err_disable_clk;
+	}
+
+	mutex_init(&ospi->mlock);
+
+	ret = f_ospi_init(ospi);
+	if (ret)
+		goto err_destroy_mutex;
+
+	ret = devm_spi_register_controller(dev, ctlr);
+	if (ret)
+		goto err_destroy_mutex;
+
+	return 0;
+
+err_destroy_mutex:
+	mutex_destroy(&ospi->mlock);
+
+err_disable_clk:
+	clk_disable_unprepare(ospi->clk);
+
+err_put_ctlr:
+	spi_controller_put(ctlr);
+
+	return ret;
+}
+
+static int f_ospi_remove(struct platform_device *pdev)
+{
+	struct f_ospi *ospi = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(ospi->clk);
+
+	mutex_destroy(&ospi->mlock);
+
+	return 0;
+}
+
+static const struct of_device_id f_ospi_dt_ids[] = {
+	{ .compatible = "socionext,f-ospi" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, f_ospi_dt_ids);
+
+static struct platform_driver f_ospi_driver = {
+	.driver = {
+		.name = "socionext,f-ospi",
+		.of_match_table = f_ospi_dt_ids,
+	},
+	.probe = f_ospi_probe,
+	.remove = f_ospi_remove,
+};
+module_platform_driver(f_ospi_driver);
+
+MODULE_DESCRIPTION("Socionext F_OSPI controller driver");
+MODULE_AUTHOR("Socionext Inc.");
+MODULE_AUTHOR("Kunihiko Hayashi <hayashi.kunihiko@socionext.com>");
+MODULE_LICENSE("GPL");
-- 
2.25.1

Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Mark Brown]

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On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:

> +  socionext,cs-start-cycle:
> +  socionext,cs-end-cycle:
> +  socionext,cs-deassert-clk-cycle:

These are all generic SPI properties so we should add them
generically, on the device rather than the controller since this
is something that might vary per client device.  There was also a
core function spi_set_cs_timing() which was in earlier versions
and is about to get reintroduced.

> +  socionext,alternative-byte:
> +    description:
> +      Specify the extra bytes to transfer after address transfer.

This just doesn't seem like something the controller should be
worrying about, the device should just send whatever the device
needs sending.  

> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    items:
> +      - description: the number of bytes to transfer
> +        maximum: 4
> +      - description: value to transfer
> +        default: 0
> +      - description: bit-width to transfer
> +        enum: [0, 1, 2, 4, 8]

This is also something SPI device should set up, as far as I can
tell this should be set vis spi_mem_op.dummy.nbytes.

> +  socionext,data-swap-2byte:
> +    description:
> +      Indicates swap byte order per 2-bytes.
> +    type: boolean

> +  socionext,data-swap-4byte:
> +    description:
> +      Indicates swap byte order per 4-bytes.
> +    type: boolean

Again these should be set by the device.  I think these should be
set based on a combination of bits per word and if the host is in
big endian or little endian mode.

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Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Kunihiko Hayashi]

Hi Mark,

Thank you for your comment.

On 2022/11/18 20:39, Mark Brown wrote:
> On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:
> 
>> +  socionext,cs-start-cycle:
>> +  socionext,cs-end-cycle:
>> +  socionext,cs-deassert-clk-cycle:
> 
> These are all generic SPI properties so we should add them
> generically, on the device rather than the controller since this
> is something that might vary per client device.  There was also a
> core function spi_set_cs_timing() which was in earlier versions
> and is about to get reintroduced.

So I understand you mean that these properties should be defined like
spi-peripheral-props.yaml for the devices.

If yes, I'll drop these properties once and define our vendor-specific
"peripheral-props" in the next series.

>> +  socionext,alternative-byte:
>> +    description:
>> +      Specify the extra bytes to transfer after address transfer.
> 
> This just doesn't seem like something the controller should be
> worrying about, the device should just send whatever the device
> needs sending.

This seems to be a feature added for the special devices,
so this should be device matter.

>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>> +    items:
>> +      - description: the number of bytes to transfer
>> +        maximum: 4
>> +      - description: value to transfer
>> +        default: 0
>> +      - description: bit-width to transfer
>> +        enum: [0, 1, 2, 4, 8]
> 
> This is also something SPI device should set up, as far as I can
> tell this should be set vis spi_mem_op.dummy.nbytes.

Yes, but the controller also supports dummy cycles, and can send
extra bytes before the dummy cycles.

>> +  socionext,data-swap-2byte:
>> +    description:
>> +      Indicates swap byte order per 2-bytes.
>> +    type: boolean
> 
>> +  socionext,data-swap-4byte:
>> +    description:
>> +      Indicates swap byte order per 4-bytes.
>> +    type: boolean
> 
> Again these should be set by the device.  I think these should be
> set based on a combination of bits per word and if the host is in
> big endian or little endian mode.

I see. This feature is complicated to use, so I'll not add it here.

Thank you,

---
Best Regards
Kunihiko Hayashi

Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 2240 bytes --]

On Fri, Nov 18, 2022 at 11:16:22PM +0900, Kunihiko Hayashi wrote:
> On 2022/11/18 20:39, Mark Brown wrote:
> > On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:

> > > +  socionext,cs-start-cycle:
> > > +  socionext,cs-end-cycle:
> > > +  socionext,cs-deassert-clk-cycle:

> > These are all generic SPI properties so we should add them
> > generically, on the device rather than the controller since this
> > is something that might vary per client device.  There was also a
> > core function spi_set_cs_timing() which was in earlier versions
> > and is about to get reintroduced.

> So I understand you mean that these properties should be defined like
> spi-peripheral-props.yaml for the devices.

> If yes, I'll drop these properties once and define our vendor-specific
> "peripheral-props" in the next series.

Yes, sounds good.

> > > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    items:
> > > +      - description: the number of bytes to transfer
> > > +        maximum: 4
> > > +      - description: value to transfer
> > > +        default: 0
> > > +      - description: bit-width to transfer
> > > +        enum: [0, 1, 2, 4, 8]

> > This is also something SPI device should set up, as far as I can
> > tell this should be set vis spi_mem_op.dummy.nbytes.

> Yes, but the controller also supports dummy cycles, and can send
> extra bytes before the dummy cycles.

Ah, so this is some additional thing on top of dummy cycles?  I'd
not realised that.  It probably wants to be added into spi-mem I
guess.

> > > +  socionext,data-swap-2byte:
> > > +    description:
> > > +      Indicates swap byte order per 2-bytes.
> > > +    type: boolean
> > 
> > > +  socionext,data-swap-4byte:
> > > +    description:
> > > +      Indicates swap byte order per 4-bytes.
> > > +    type: boolean

> > Again these should be set by the device.  I think these should be
> > set based on a combination of bits per word and if the host is in
> > big endian or little endian mode.

> I see. This feature is complicated to use, so I'll not add it here.

That also works, someone can always add additional support later
when they have a concrete use case.

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Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Kunihiko Hayashi]

On 2022/11/19 0:36, Mark Brown wrote:
> On Fri, Nov 18, 2022 at 11:16:22PM +0900, Kunihiko Hayashi wrote:
>> On 2022/11/18 20:39, Mark Brown wrote:
>>> On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:
> 
>>>> +  socionext,cs-start-cycle:
>>>> +  socionext,cs-end-cycle:
>>>> +  socionext,cs-deassert-clk-cycle:
> 
>>> These are all generic SPI properties so we should add them
>>> generically, on the device rather than the controller since this
>>> is something that might vary per client device.  There was also a
>>> core function spi_set_cs_timing() which was in earlier versions
>>> and is about to get reintroduced.
> 
>> So I understand you mean that these properties should be defined like
>> spi-peripheral-props.yaml for the devices.
> 
>> If yes, I'll drop these properties once and define our vendor-specific
>> "peripheral-props" in the next series.
> 
> Yes, sounds good.

Okay, I'll send simple one in v2.

>>>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>>>> +    items:
>>>> +      - description: the number of bytes to transfer
>>>> +        maximum: 4
>>>> +      - description: value to transfer
>>>> +        default: 0
>>>> +      - description: bit-width to transfer
>>>> +        enum: [0, 1, 2, 4, 8]
> 
>>> This is also something SPI device should set up, as far as I can
>>> tell this should be set vis spi_mem_op.dummy.nbytes.
> 
>> Yes, but the controller also supports dummy cycles, and can send
>> extra bytes before the dummy cycles.
> 
> Ah, so this is some additional thing on top of dummy cycles?  I'd
> not realised that.  It probably wants to be added into spi-mem I
> guess.

Yes, however, it's tough to handle with spi-mem and I don't have
any use case, so drop it.

>>>> +  socionext,data-swap-2byte:
>>>> +    description:
>>>> +      Indicates swap byte order per 2-bytes.
>>>> +    type: boolean
>>>
>>>> +  socionext,data-swap-4byte:
>>>> +    description:
>>>> +      Indicates swap byte order per 4-bytes.
>>>> +    type: boolean
> 
>>> Again these should be set by the device.  I think these should be
>>> set based on a combination of bits per word and if the host is in
>>> big endian or little endian mode.
> 
>> I see. This feature is complicated to use, so I'll not add it here.
> 
> That also works, someone can always add additional support later
> when they have a concrete use case.

I understand.

Thank you,

---
Best Regards
Kunihiko Hayashi