[PATCH v3 0/9] Add Tegra Quad SPI driver

[PATCH v3 0/9] Add Tegra Quad SPI driver

[Sowjanya Komatineni]

This series adds Tegra210, Tegra186, and Tegra194 Quad SPI driver and
enables Quad SPI on Jetson Nano and Jetson Xavier NX.

QSPI controller is available on Tegra210, Tegra186 and Tegra194.

Tegra186 and Tegra194 has additional feature of combined sequence mode
where command, address and data can all be transferred in a single transfer.

Combined sequence mode is useful with DMA mode transfer.

This series does not have combined sequence mode feature as Tegra186/Tegra194
GPCDMA driver is not upstreamed yet.

This series includes
- dt-binding document
- QSPI driver for Tegra210/Tegra186/Tegra194
- Enables QSPI on Jetson Nano and Jetson Xavier NX.

Delta between patch versions:
[v3]:	v2 has some mixed patches sent out accidentally.
	v3 sends proper patches with fixes mentioned in v2.
[v2]:	below v1 feedback
	- Added SPI_MASTER_USES_HW_DUMMY_CYCLES flag for controllers supporting
	  hardware dummy cycles and skips dummy bytes transfer from software for
	  these controllers.
	- Updated dt-binding doc with tx/rx tap delay properties.
	- Added qspi_out clock to dt-binding doc which will be used later with
	  ddr mode support.
	- All other v1 feedback on some cleanup.



Sowjanya Komatineni (9):
  dt-bindings: clock: tegra: Add clock ID TEGRA210_CLK_QSPI_PM
  dt-bindings: spi: Add Tegra Quad SPI device tree binding
  MAINTAINERS: Add Tegra Quad SPI driver section
  spi: tegra210-quad: Add support for Tegra210 QSPI controller
  spi: spi-mem: Allow masters to transfer dummy cycles directly by
    hardware
  spi: tegra210-quad: Add support for hardware dummy cycles
  arm64: tegra: Enable QSPI on Jetson Nano
  arm64: tegra: Add QSPI nodes on Tegra194
  arm64: tegra: Enable QSPI on Jetson Xavier NX

 .../bindings/spi/nvidia,tegra210-quad.yaml         |  130 ++
 MAINTAINERS                                        |    8 +
 .../dts/nvidia/tegra194-p3509-0000+p3668-0000.dts  |   12 +
 arch/arm64/boot/dts/nvidia/tegra194.dtsi           |   24 +
 arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts |   12 +
 arch/arm64/boot/dts/nvidia/tegra210.dtsi           |    5 +-
 drivers/spi/Kconfig                                |    9 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-mem.c                              |   18 +-
 drivers/spi/spi-tegra210-quad.c                    | 1407 ++++++++++++++++++++
 include/dt-bindings/clock/tegra210-car.h           |    2 +-
 include/linux/spi/spi.h                            |    8 +
 12 files changed, 1626 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
 create mode 100644 drivers/spi/spi-tegra210-quad.c

-- 
2.7.4

[PATCH v3 1/9] dt-bindings: clock: tegra: Add clock ID TEGRA210_CLK_QSPI_PM

[Sowjanya Komatineni]

Tegra210 QSPI clock output has divider DIV2_SEL which will be enabled
when using DDR interface mode.

This patch adds clock ID for this to dt-binding.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 include/dt-bindings/clock/tegra210-car.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/dt-bindings/clock/tegra210-car.h b/include/dt-bindings/clock/tegra210-car.h
index ab8b8a7..9cfcc3b 100644
--- a/include/dt-bindings/clock/tegra210-car.h
+++ b/include/dt-bindings/clock/tegra210-car.h
@@ -307,7 +307,7 @@
 #define TEGRA210_CLK_AUDIO4 275
 #define TEGRA210_CLK_SPDIF 276
 /* 277 */
-/* 278 */
+#define TEGRA210_CLK_QSPI_PM 278
 /* 279 */
 /* 280 */
 #define TEGRA210_CLK_SOR0_LVDS 281 /* deprecated */
-- 
2.7.4

[PATCH v3 2/9] dt-bindings: spi: Add Tegra Quad SPI device tree binding

[Sowjanya Komatineni]

This patch adds YAML based device tree binding document for Tegra
Quad SPI driver.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 .../bindings/spi/nvidia,tegra210-quad.yaml         | 130 +++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml

diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
new file mode 100644
index 0000000..0b5fea6
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
@@ -0,0 +1,130 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/nvidia,tegra210-quad.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Tegra Quad SPI Controller
+
+maintainers:
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Jonathan Hunter <jonathanh@nvidia.com>
+
+properties:
+  compatible:
+    enum:
+      - nvidia,tegra210-qspi
+      - nvidia,tegra186-qspi
+      - nvidia,tegra194-qspi
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: qspi
+      - const: qspi_out
+
+  clocks:
+    maxItems: 2
+
+  resets:
+    maxItems: 1
+
+  dmas:
+    maxItems: 2
+
+  dma-names:
+    items:
+      - const: rx
+      - const: tx
+
+patternProperties:
+  "^.*@[0-9a-f]+":
+    type: object
+
+    properties:
+      compatible:
+        description:
+          Compatible of the SPI device.
+
+      reg:
+        maxItems: 1
+
+      spi-max-frequency:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description:
+          Maximum Quad SPI clocking speed of the device in Hz.
+
+      spi-rx-bus-width:
+        description:
+          Bus width to the Quad SPI bus used for read transfers.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [1, 2, 4]
+
+      spi-tx-bus-width:
+        description:
+          Bus width to the Quad SPI bus used for write transfers.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [1, 2, 4]
+
+      nvidia,tx-clk-tap-delay:
+        description:
+          Delays the clock going out to device with this tap value.
+          Tap value varies based on platform design trace lengths from Tegra
+          QSPI to corresponding slave device.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 31
+
+      nvidia,rx-clk-tap-delay:
+        description:
+          Delays the clock coming in from the device with this tap value.
+          Tap value varies based on platform design trace lengths from Tegra
+          QSPI to corresponding slave device.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 255
+
+    required:
+      - reg
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clock-names
+  - clocks
+  - resets
+
+additionalProperties: true
+
+examples:
+  - |
+    #include <dt-bindings/clock/tegra210-car.h>
+    #include <dt-bindings/reset/tegra210-car.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    spi@70410000 {
+            compatible = "nvidia,tegra210-qspi";
+            reg = <0x70410000 0x1000>;
+            interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            clocks = <&tegra_car TEGRA210_CLK_QSPI>,
+                     <&tegra_car TEGRA210_CLK_QSPI_PM>;
+            clock-names = "qspi", "qspi_out";
+            resets = <&tegra_car 211>;
+            dmas = <&apbdma 5>, <&apbdma 5>;
+            dma-names = "rx", "tx";
+
+            flash@0 {
+                    compatible = "spi-nor";
+                    reg = <0>;
+                    spi-max-frequency = <104000000>;
+                    spi-tx-bus-width = <2>;
+                    spi-rx-bus-width = <2>;
+            };
+    };
-- 
2.7.4

[PATCH v3 3/9] MAINTAINERS: Add Tegra Quad SPI driver section

[Sowjanya Komatineni]

Add maintainers and mailing list entries to Tegra Quad SPI driver
section.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5b20bab..19db61f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17447,6 +17447,14 @@ M:	Laxman Dewangan <ldewangan@nvidia.com>
 S:	Supported
 F:	drivers/spi/spi-tegra*
 
+TEGRA QUAD SPI DRIVER
+M:	Thierry Reding <thierry.reding@gmail.com>
+M:	Jonathan Hunter <jonathanh@nvidia.com>
+M:	Sowjanya Komatineni <skomatineni@nvidia.com>
+L:	linux-tegra@vger.kernel.org
+S:	Maintained
+F:	drivers/spi/spi-tegra210-quad.c
+
 TEGRA VIDEO DRIVER
 M:	Thierry Reding <thierry.reding@gmail.com>
 M:	Jonathan Hunter <jonathanh@nvidia.com>
-- 
2.7.4

[PATCH v3 4/9] spi: tegra210-quad: Add support for Tegra210 QSPI controller

[Sowjanya Komatineni]

Tegra SoC has a Quad SPI controller starting from Tegra210.

This patch adds support for Tegra210 QSPI controller.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 drivers/spi/Kconfig             |    9 +
 drivers/spi/Makefile            |    1 +
 drivers/spi/spi-tegra210-quad.c | 1387 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 1397 insertions(+)
 create mode 100644 drivers/spi/spi-tegra210-quad.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index aadaea0..f56f20e 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -843,6 +843,15 @@ config SPI_MXS
 	help
 	  SPI driver for Freescale MXS devices.
 
+config SPI_TEGRA210_QUAD
+	tristate "NVIDIA Tegra QSPI Controller"
+	depends on ARCH_TEGRA || COMPILE_TEST
+	depends on RESET_CONTROLLER
+	help
+	  QSPI driver for NVIDIA Tegra QSPI Controller interface. This
+	  controller is different from the SPI controller and is available
+	  on Tegra SoCs starting from Tegra210.
+
 config SPI_TEGRA114
 	tristate "NVIDIA Tegra114 SPI Controller"
 	depends on (ARCH_TEGRA && TEGRA20_APB_DMA) || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 6fea582..c822c5e 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -115,6 +115,7 @@ obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
 obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
 obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
 obj-$(CONFIG_SPI_SYNQUACER)		+= spi-synquacer.o
+obj-$(CONFIG_SPI_TEGRA210_QUAD)		+= spi-tegra210-quad.o
 obj-$(CONFIG_SPI_TEGRA114)		+= spi-tegra114.o
 obj-$(CONFIG_SPI_TEGRA20_SFLASH)	+= spi-tegra20-sflash.o
 obj-$(CONFIG_SPI_TEGRA20_SLINK)		+= spi-tegra20-slink.o
diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
new file mode 100644
index 0000000..624f395
--- /dev/null
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -0,0 +1,1387 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright (C) 2020 NVIDIA CORPORATION.
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define QSPI_COMMAND1				0x000
+#define QSPI_BIT_LENGTH(x)			(((x) & 0x1f) << 0)
+#define QSPI_PACKED				BIT(5)
+#define QSPI_INTERFACE_WIDTH_MASK		(0x03 << 7)
+#define QSPI_INTERFACE_WIDTH(x)			(((x) & 0x03) << 7)
+#define QSPI_INTERFACE_WIDTH_SINGLE		QSPI_INTERFACE_WIDTH(0)
+#define QSPI_INTERFACE_WIDTH_DUAL		QSPI_INTERFACE_WIDTH(1)
+#define QSPI_INTERFACE_WIDTH_QUAD		QSPI_INTERFACE_WIDTH(2)
+#define QSPI_SDR_DDR_SEL			BIT(9)
+#define QSPI_TX_EN				BIT(11)
+#define QSPI_RX_EN				BIT(12)
+#define QSPI_CS_SW_VAL				BIT(20)
+#define QSPI_CS_SW_HW				BIT(21)
+#define QSPI_CONTROL_MODE_0			(0 << 28)
+#define QSPI_CONTROL_MODE_3			(3 << 28)
+#define QSPI_CONTROL_MODE_MASK			(3 << 28)
+#define QSPI_M_S				BIT(30)
+#define QSPI_PIO				BIT(31)
+
+#define QSPI_COMMAND2				0x004
+#define QSPI_TX_TAP_DELAY(x)			(((x) & 0x3f) << 10)
+#define QSPI_RX_TAP_DELAY(x)			(((x) & 0xff) << 0)
+
+#define QSPI_CS_TIMING1				0x008
+#define QSPI_SETUP_HOLD(setup, hold)		(((setup) << 4) | (hold))
+
+#define QSPI_CS_TIMING2				0x00c
+#define CYCLES_BETWEEN_PACKETS_0(x)		(((x) & 0x1f) << 0)
+#define CS_ACTIVE_BETWEEN_PACKETS_0		BIT(5)
+
+#define QSPI_TRANS_STATUS			0x010
+#define QSPI_BLK_CNT(val)			(((val) >> 0) & 0xffff)
+#define QSPI_RDY				BIT(30)
+
+#define QSPI_FIFO_STATUS			0x014
+#define QSPI_RX_FIFO_EMPTY			BIT(0)
+#define QSPI_RX_FIFO_FULL			BIT(1)
+#define QSPI_TX_FIFO_EMPTY			BIT(2)
+#define QSPI_TX_FIFO_FULL			BIT(3)
+#define QSPI_RX_FIFO_UNF			BIT(4)
+#define QSPI_RX_FIFO_OVF			BIT(5)
+#define QSPI_TX_FIFO_UNF			BIT(6)
+#define QSPI_TX_FIFO_OVF			BIT(7)
+#define QSPI_ERR				BIT(8)
+#define QSPI_TX_FIFO_FLUSH			BIT(14)
+#define QSPI_RX_FIFO_FLUSH			BIT(15)
+#define QSPI_TX_FIFO_EMPTY_COUNT(val)		(((val) >> 16) & 0x7f)
+#define QSPI_RX_FIFO_FULL_COUNT(val)		(((val) >> 23) & 0x7f)
+
+#define QSPI_FIFO_ERROR				(QSPI_RX_FIFO_UNF | \
+						 QSPI_RX_FIFO_OVF | \
+						 QSPI_TX_FIFO_UNF | \
+						 QSPI_TX_FIFO_OVF)
+#define QSPI_FIFO_EMPTY				(QSPI_RX_FIFO_EMPTY | \
+						 QSPI_TX_FIFO_EMPTY)
+
+#define QSPI_TX_DATA				0x018
+#define QSPI_RX_DATA				0x01c
+
+#define QSPI_DMA_CTL				0x020
+#define QSPI_TX_TRIG(n)				(((n) & 0x3) << 15)
+#define QSPI_TX_TRIG_1				QSPI_TX_TRIG(0)
+#define QSPI_TX_TRIG_4				QSPI_TX_TRIG(1)
+#define QSPI_TX_TRIG_8				QSPI_TX_TRIG(2)
+#define QSPI_TX_TRIG_16				QSPI_TX_TRIG(3)
+
+#define QSPI_RX_TRIG(n)				(((n) & 0x3) << 19)
+#define QSPI_RX_TRIG_1				QSPI_RX_TRIG(0)
+#define QSPI_RX_TRIG_4				QSPI_RX_TRIG(1)
+#define QSPI_RX_TRIG_8				QSPI_RX_TRIG(2)
+#define QSPI_RX_TRIG_16				QSPI_RX_TRIG(3)
+
+#define QSPI_DMA_EN				BIT(31)
+
+#define QSPI_DMA_BLK				0x024
+#define QSPI_DMA_BLK_SET(x)			(((x) & 0xffff) << 0)
+
+#define QSPI_TX_FIFO				0x108
+#define QSPI_RX_FIFO				0x188
+
+#define QSPI_FIFO_DEPTH				64
+
+#define QSPI_INTR_MASK				0x18c
+#define QSPI_INTR_RX_FIFO_UNF_MASK		BIT(25)
+#define QSPI_INTR_RX_FIFO_OVF_MASK		BIT(26)
+#define QSPI_INTR_TX_FIFO_UNF_MASK		BIT(27)
+#define QSPI_INTR_TX_FIFO_OVF_MASK		BIT(28)
+#define QSPI_INTR_RDY_MASK			BIT(29)
+#define QSPI_INTR_RX_TX_FIFO_ERR		(QSPI_INTR_RX_FIFO_UNF_MASK | \
+						 QSPI_INTR_RX_FIFO_OVF_MASK | \
+						 QSPI_INTR_TX_FIFO_UNF_MASK | \
+						 QSPI_INTR_TX_FIFO_OVF_MASK)
+
+#define QSPI_MISC_REG                           0x194
+#define QSPI_NUM_DUMMY_CYCLE(x)			(((x) & 0xff) << 0)
+
+#define DATA_DIR_TX				BIT(0)
+#define DATA_DIR_RX				BIT(1)
+
+#define QSPI_DMA_TIMEOUT			(msecs_to_jiffies(1000))
+#define DEFAULT_QSPI_DMA_BUF_LEN		(64 * 1024)
+
+struct tegra_qspi_client_data {
+	int tx_clk_tap_delay;
+	int rx_clk_tap_delay;
+};
+
+struct tegra_qspi {
+	struct device				*dev;
+	struct spi_master			*master;
+	/* lock to protect data accessed by irq */
+	spinlock_t				lock;
+
+	struct clk				*clk;
+	struct reset_control			*rst;
+	void __iomem				*base;
+	phys_addr_t				phys;
+	unsigned int				irq;
+
+	u32					cur_speed;
+	unsigned int				cur_pos;
+	unsigned int				words_per_32bit;
+	unsigned int				bytes_per_word;
+	unsigned int				curr_dma_words;
+	unsigned int				cur_direction;
+
+	unsigned int				cur_rx_pos;
+	unsigned int				cur_tx_pos;
+
+	unsigned int				dma_buf_size;
+	unsigned int				max_buf_size;
+	bool					is_curr_dma_xfer;
+
+	struct completion			rx_dma_complete;
+	struct completion			tx_dma_complete;
+
+	u32					tx_status;
+	u32					rx_status;
+	u32					status_reg;
+	bool					is_packed;
+	bool					use_dma;
+
+	u32					command1_reg;
+	u32					dma_control_reg;
+	u32					def_command1_reg;
+	u32					def_command2_reg;
+	u32					spi_cs_timing1;
+	u32					spi_cs_timing2;
+	u8					dummy_cycles;
+
+	struct completion			xfer_completion;
+	struct spi_transfer			*curr_xfer;
+
+	struct dma_chan				*rx_dma_chan;
+	u32					*rx_dma_buf;
+	dma_addr_t				rx_dma_phys;
+	struct dma_async_tx_descriptor		*rx_dma_desc;
+
+	struct dma_chan				*tx_dma_chan;
+	u32					*tx_dma_buf;
+	dma_addr_t				tx_dma_phys;
+	struct dma_async_tx_descriptor		*tx_dma_desc;
+};
+
+static inline u32 tegra_qspi_readl(struct tegra_qspi *tqspi, unsigned long offset)
+{
+	return readl(tqspi->base + offset);
+}
+
+static inline void tegra_qspi_writel(struct tegra_qspi *tqspi, u32 value, unsigned long offset)
+{
+	writel(value, tqspi->base + offset);
+
+	/* read back register to make sure that register writes completed */
+	if (offset != QSPI_TX_FIFO)
+		readl(tqspi->base + QSPI_COMMAND1);
+}
+
+static void tegra_qspi_mask_clear_irq(struct tegra_qspi *tqspi)
+{
+	u32 value;
+
+	/* write 1 to clear status register */
+	value = tegra_qspi_readl(tqspi, QSPI_TRANS_STATUS);
+	tegra_qspi_writel(tqspi, value, QSPI_TRANS_STATUS);
+
+	value = tegra_qspi_readl(tqspi, QSPI_INTR_MASK);
+	if (!(value & QSPI_INTR_RDY_MASK)) {
+		value |= (QSPI_INTR_RDY_MASK | QSPI_INTR_RX_TX_FIFO_ERR);
+		tegra_qspi_writel(tqspi, value, QSPI_INTR_MASK);
+	}
+
+	/* clear fifo status error if any */
+	value = tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS);
+	if (value & QSPI_ERR)
+		tegra_qspi_writel(tqspi, QSPI_ERR | QSPI_FIFO_ERROR, QSPI_FIFO_STATUS);
+}
+
+static unsigned int
+tegra_qspi_calculate_curr_xfer_param(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	unsigned int max_word, max_len, total_fifo_words;
+	unsigned int remain_len = t->len - tqspi->cur_pos;
+	unsigned int bits_per_word = t->bits_per_word;
+
+	tqspi->bytes_per_word = DIV_ROUND_UP(bits_per_word, 8);
+
+	/*
+	 * Tegra QSPI controller supports packed or unpacked mode transfers.
+	 * Packed mode is used for data transfers using 8, 16, or 32 bits per
+	 * word with a minimum transfer of 1 word and for all other transfers
+	 * unpacked mode will be used.
+	 */
+
+	if ((bits_per_word == 8 || bits_per_word == 16 ||
+	     bits_per_word == 32) && t->len > 3) {
+		tqspi->is_packed = true;
+		tqspi->words_per_32bit = 32 / bits_per_word;
+	} else {
+		tqspi->is_packed = false;
+		tqspi->words_per_32bit = 1;
+	}
+
+	if (tqspi->is_packed) {
+		max_len = min(remain_len, tqspi->max_buf_size);
+		tqspi->curr_dma_words = max_len / tqspi->bytes_per_word;
+		total_fifo_words = (max_len + 3) / 4;
+	} else {
+		max_word = (remain_len - 1) / tqspi->bytes_per_word + 1;
+		max_word = min(max_word, tqspi->max_buf_size / 4);
+		tqspi->curr_dma_words = max_word;
+		total_fifo_words = max_word;
+	}
+
+	return total_fifo_words;
+}
+
+static unsigned int
+tegra_qspi_fill_tx_fifo_from_client_txbuf(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	unsigned int written_words, fifo_words_left, count;
+	unsigned int len, tx_empty_count, max_n_32bit, i;
+	u8 *tx_buf = (u8 *)t->tx_buf + tqspi->cur_tx_pos;
+	u32 fifo_status;
+
+	fifo_status = tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS);
+	tx_empty_count = QSPI_TX_FIFO_EMPTY_COUNT(fifo_status);
+
+	if (tqspi->is_packed) {
+		fifo_words_left = tx_empty_count * tqspi->words_per_32bit;
+		written_words = min(fifo_words_left, tqspi->curr_dma_words);
+		len = written_words * tqspi->bytes_per_word;
+		max_n_32bit = DIV_ROUND_UP(len, 4);
+		for (count = 0; count < max_n_32bit; count++) {
+			u32 x = 0;
+
+			for (i = 0; (i < 4) && len; i++, len--)
+				x |= (u32)(*tx_buf++) << (i * 8);
+			tegra_qspi_writel(tqspi, x, QSPI_TX_FIFO);
+		}
+
+		tqspi->cur_tx_pos += written_words * tqspi->bytes_per_word;
+	} else {
+		unsigned int write_bytes;
+		u8 bytes_per_word = tqspi->bytes_per_word;
+
+		max_n_32bit = min(tqspi->curr_dma_words, tx_empty_count);
+		written_words = max_n_32bit;
+		len = written_words * tqspi->bytes_per_word;
+		if (len > t->len - tqspi->cur_pos)
+			len = t->len - tqspi->cur_pos;
+		write_bytes = len;
+		for (count = 0; count < max_n_32bit; count++) {
+			u32 x = 0;
+
+			for (i = 0; len && (i < bytes_per_word); i++, len--)
+				x |= (u32)(*tx_buf++) << (i * 8);
+			tegra_qspi_writel(tqspi, x, QSPI_TX_FIFO);
+		}
+
+		tqspi->cur_tx_pos += write_bytes;
+	}
+
+	return written_words;
+}
+
+static unsigned int
+tegra_qspi_read_rx_fifo_to_client_rxbuf(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	u8 *rx_buf = (u8 *)t->rx_buf + tqspi->cur_rx_pos;
+	unsigned int len, rx_full_count, count, i;
+	unsigned int read_words = 0;
+	u32 fifo_status, x;
+
+	fifo_status = tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS);
+	rx_full_count = QSPI_RX_FIFO_FULL_COUNT(fifo_status);
+	if (tqspi->is_packed) {
+		len = tqspi->curr_dma_words * tqspi->bytes_per_word;
+		for (count = 0; count < rx_full_count; count++) {
+			x = tegra_qspi_readl(tqspi, QSPI_RX_FIFO);
+
+			for (i = 0; len && (i < 4); i++, len--)
+				*rx_buf++ = (x >> i * 8) & 0xff;
+		}
+
+		read_words += tqspi->curr_dma_words;
+		tqspi->cur_rx_pos += tqspi->curr_dma_words * tqspi->bytes_per_word;
+	} else {
+		u32 rx_mask = ((u32)1 << t->bits_per_word) - 1;
+		u8 bytes_per_word = tqspi->bytes_per_word;
+		unsigned int read_bytes;
+
+		len = rx_full_count * bytes_per_word;
+		if (len > t->len - tqspi->cur_pos)
+			len = t->len - tqspi->cur_pos;
+		read_bytes = len;
+		for (count = 0; count < rx_full_count; count++) {
+			x = tegra_qspi_readl(tqspi, QSPI_RX_FIFO) & rx_mask;
+
+			for (i = 0; len && (i < bytes_per_word); i++, len--)
+				*rx_buf++ = (x >> (i * 8)) & 0xff;
+		}
+
+		read_words += rx_full_count;
+		tqspi->cur_rx_pos += read_bytes;
+	}
+
+	return read_words;
+}
+
+static void
+tegra_qspi_copy_client_txbuf_to_qspi_txbuf(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	dma_sync_single_for_cpu(tqspi->dev, tqspi->tx_dma_phys,
+				tqspi->dma_buf_size, DMA_TO_DEVICE);
+
+	/*
+	 * In packed mode, each word in FIFO may contain multiple packets
+	 * based on bits per word. So all bytes in each FIFO word are valid.
+	 *
+	 * In unpacked mode, each word in FIFO contains single packet and
+	 * based on bits per word any remaining bits in FIFO word will be
+	 * ignored by the hardware and are invalid bits.
+	 */
+	if (tqspi->is_packed) {
+		tqspi->cur_tx_pos += tqspi->curr_dma_words * tqspi->bytes_per_word;
+	} else {
+		u8 *tx_buf = (u8 *)t->tx_buf + tqspi->cur_tx_pos;
+		unsigned int i, count, consume, write_bytes;
+
+		/*
+		 * Fill tx_dma_buf to contain single packet in each word based
+		 * on bits per word from SPI core tx_buf.
+		 */
+		consume = tqspi->curr_dma_words * tqspi->bytes_per_word;
+		if (consume > t->len - tqspi->cur_pos)
+			consume = t->len - tqspi->cur_pos;
+		write_bytes = consume;
+		for (count = 0; count < tqspi->curr_dma_words; count++) {
+			u32 x = 0;
+
+			for (i = 0; consume && (i < tqspi->bytes_per_word); i++, consume--)
+				x |= (u32)(*tx_buf++) << (i * 8);
+			tqspi->tx_dma_buf[count] = x;
+		}
+
+		tqspi->cur_tx_pos += write_bytes;
+	}
+
+	dma_sync_single_for_device(tqspi->dev, tqspi->tx_dma_phys,
+				   tqspi->dma_buf_size, DMA_TO_DEVICE);
+}
+
+static void
+tegra_qspi_copy_qspi_rxbuf_to_client_rxbuf(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	dma_sync_single_for_cpu(tqspi->dev, tqspi->rx_dma_phys,
+				tqspi->dma_buf_size, DMA_FROM_DEVICE);
+
+	if (tqspi->is_packed) {
+		tqspi->cur_rx_pos += tqspi->curr_dma_words * tqspi->bytes_per_word;
+	} else {
+		unsigned char *rx_buf = t->rx_buf + tqspi->cur_rx_pos;
+		u32 rx_mask = ((u32)1 << t->bits_per_word) - 1;
+		unsigned int i, count, consume, read_bytes;
+
+		/*
+		 * Each FIFO word contains single data packet.
+		 * Skip invalid bits in each FIFO word based on bits per word
+		 * and align bytes while filling in SPI core rx_buf.
+		 */
+		consume = tqspi->curr_dma_words * tqspi->bytes_per_word;
+		if (consume > t->len - tqspi->cur_pos)
+			consume = t->len - tqspi->cur_pos;
+		read_bytes = consume;
+		for (count = 0; count < tqspi->curr_dma_words; count++) {
+			u32 x = tqspi->rx_dma_buf[count] & rx_mask;
+
+			for (i = 0; consume && (i < tqspi->bytes_per_word); i++, consume--)
+				*rx_buf++ = (x >> (i * 8)) & 0xff;
+		}
+
+		tqspi->cur_rx_pos += read_bytes;
+	}
+
+	dma_sync_single_for_device(tqspi->dev, tqspi->rx_dma_phys,
+				   tqspi->dma_buf_size, DMA_FROM_DEVICE);
+}
+
+static void tegra_qspi_dma_complete(void *args)
+{
+	struct completion *dma_complete = args;
+
+	complete(dma_complete);
+}
+
+static int tegra_qspi_start_tx_dma(struct tegra_qspi *tqspi, struct spi_transfer *t, int len)
+{
+	dma_addr_t tx_dma_phys;
+
+	reinit_completion(&tqspi->tx_dma_complete);
+
+	if (tqspi->is_packed)
+		tx_dma_phys = t->tx_dma;
+	else
+		tx_dma_phys = tqspi->tx_dma_phys;
+
+	tqspi->tx_dma_desc = dmaengine_prep_slave_single(tqspi->tx_dma_chan, tx_dma_phys,
+							 len, DMA_MEM_TO_DEV,
+							 DMA_PREP_INTERRUPT |  DMA_CTRL_ACK);
+
+	if (!tqspi->tx_dma_desc) {
+		dev_err(tqspi->dev, "Unable to get TX descriptor\n");
+		return -EIO;
+	}
+
+	tqspi->tx_dma_desc->callback = tegra_qspi_dma_complete;
+	tqspi->tx_dma_desc->callback_param = &tqspi->tx_dma_complete;
+	dmaengine_submit(tqspi->tx_dma_desc);
+	dma_async_issue_pending(tqspi->tx_dma_chan);
+
+	return 0;
+}
+
+static int tegra_qspi_start_rx_dma(struct tegra_qspi *tqspi, struct spi_transfer *t, int len)
+{
+	dma_addr_t rx_dma_phys;
+
+	reinit_completion(&tqspi->rx_dma_complete);
+
+	if (tqspi->is_packed)
+		rx_dma_phys = t->rx_dma;
+	else
+		rx_dma_phys = tqspi->rx_dma_phys;
+
+	tqspi->rx_dma_desc = dmaengine_prep_slave_single(tqspi->rx_dma_chan, rx_dma_phys,
+							 len, DMA_DEV_TO_MEM,
+							 DMA_PREP_INTERRUPT |  DMA_CTRL_ACK);
+
+	if (!tqspi->rx_dma_desc) {
+		dev_err(tqspi->dev, "Unable to get RX descriptor\n");
+		return -EIO;
+	}
+
+	tqspi->rx_dma_desc->callback = tegra_qspi_dma_complete;
+	tqspi->rx_dma_desc->callback_param = &tqspi->rx_dma_complete;
+	dmaengine_submit(tqspi->rx_dma_desc);
+	dma_async_issue_pending(tqspi->rx_dma_chan);
+
+	return 0;
+}
+
+static int tegra_qspi_flush_fifos(struct tegra_qspi *tqspi, bool atomic)
+{
+	void __iomem *addr = tqspi->base + QSPI_FIFO_STATUS;
+	u32 val;
+
+	val = tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS);
+	if ((val & QSPI_FIFO_EMPTY) == QSPI_FIFO_EMPTY)
+		return 0;
+
+	val |= QSPI_RX_FIFO_FLUSH | QSPI_TX_FIFO_FLUSH;
+	tegra_qspi_writel(tqspi, val, QSPI_FIFO_STATUS);
+
+	if (!atomic)
+		return readl_relaxed_poll_timeout(addr, val,
+						  (val & QSPI_FIFO_EMPTY) == QSPI_FIFO_EMPTY,
+						  1000, 1000000);
+
+	return readl_relaxed_poll_timeout_atomic(addr, val,
+						 (val & QSPI_FIFO_EMPTY) == QSPI_FIFO_EMPTY,
+						 1000, 1000000);
+}
+
+static void tegra_qspi_unmask_irq(struct tegra_qspi *tqspi)
+{
+	u32 intr_mask;
+
+	intr_mask = tegra_qspi_readl(tqspi, QSPI_INTR_MASK);
+	intr_mask &= ~(QSPI_INTR_RDY_MASK | QSPI_INTR_RX_TX_FIFO_ERR);
+	tegra_qspi_writel(tqspi, intr_mask, QSPI_INTR_MASK);
+}
+
+static int tegra_qspi_dma_map_xfer(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	u8 *tx_buf = (u8 *)t->tx_buf + tqspi->cur_tx_pos;
+	u8 *rx_buf = (u8 *)t->rx_buf + tqspi->cur_rx_pos;
+	unsigned int len;
+
+	len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
+
+	if (t->tx_buf) {
+		t->tx_dma = dma_map_single(tqspi->dev, (void *)tx_buf, len, DMA_TO_DEVICE);
+		if (dma_mapping_error(tqspi->dev, t->tx_dma))
+			return -ENOMEM;
+	}
+
+	if (t->rx_buf) {
+		t->rx_dma = dma_map_single(tqspi->dev, (void *)rx_buf, len, DMA_FROM_DEVICE);
+		if (dma_mapping_error(tqspi->dev, t->rx_dma)) {
+			dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+static void tegra_qspi_dma_unmap_xfer(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	unsigned int len;
+
+	len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
+
+	dma_unmap_single(tqspi->dev, t->tx_dma, len, DMA_TO_DEVICE);
+	dma_unmap_single(tqspi->dev, t->rx_dma, len, DMA_FROM_DEVICE);
+}
+
+static int tegra_qspi_start_dma_based_transfer(struct tegra_qspi *tqspi, struct spi_transfer *t)
+{
+	struct dma_slave_config dma_sconfig = { 0 };
+	unsigned int len;
+	u8 dma_burst;
+	int ret = 0;
+	u32 val;
+
+	if (tqspi->is_packed) {
+		ret = tegra_qspi_dma_map_xfer(tqspi, t);
+		if (ret < 0)
+			return ret;
+	}
+
+	val = QSPI_DMA_BLK_SET(tqspi->curr_dma_words - 1);
+	tegra_qspi_writel(tqspi, val, QSPI_DMA_BLK);
+
+	tegra_qspi_unmask_irq(tqspi);
+
+	if (tqspi->is_packed)
+		len = DIV_ROUND_UP(tqspi->curr_dma_words * tqspi->bytes_per_word, 4) * 4;
+	else
+		len = tqspi->curr_dma_words * 4;
+
+	/* set attention level based on length of transfer */
+	val = 0;
+	if (len & 0xf) {
+		val |= QSPI_TX_TRIG_1 | QSPI_RX_TRIG_1;
+		dma_burst = 1;
+	} else if (((len) >> 4) & 0x1) {
+		val |= QSPI_TX_TRIG_4 | QSPI_RX_TRIG_4;
+		dma_burst = 4;
+	} else {
+		val |= QSPI_TX_TRIG_8 | QSPI_RX_TRIG_8;
+		dma_burst = 8;
+	}
+
+	tegra_qspi_writel(tqspi, val, QSPI_DMA_CTL);
+	tqspi->dma_control_reg = val;
+
+	dma_sconfig.device_fc = true;
+	if (tqspi->cur_direction & DATA_DIR_TX) {
+		dma_sconfig.dst_addr = tqspi->phys + QSPI_TX_FIFO;
+		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		dma_sconfig.dst_maxburst = dma_burst;
+		ret = dmaengine_slave_config(tqspi->tx_dma_chan, &dma_sconfig);
+		if (ret < 0) {
+			dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
+			return ret;
+		}
+
+		tegra_qspi_copy_client_txbuf_to_qspi_txbuf(tqspi, t);
+		ret = tegra_qspi_start_tx_dma(tqspi, t, len);
+		if (ret < 0) {
+			dev_err(tqspi->dev, "failed to starting TX DMA: %d\n", ret);
+			return ret;
+		}
+	}
+
+	if (tqspi->cur_direction & DATA_DIR_RX) {
+		dma_sconfig.src_addr = tqspi->phys + QSPI_RX_FIFO;
+		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		dma_sconfig.src_maxburst = dma_burst;
+		ret = dmaengine_slave_config(tqspi->rx_dma_chan, &dma_sconfig);
+		if (ret < 0) {
+			dev_err(tqspi->dev, "failed DMA slave config: %d\n", ret);
+			return ret;
+		}
+
+		dma_sync_single_for_device(tqspi->dev, tqspi->rx_dma_phys,
+					   tqspi->dma_buf_size,
+					   DMA_FROM_DEVICE);
+
+		ret = tegra_qspi_start_rx_dma(tqspi, t, len);
+		if (ret < 0) {
+			dev_err(tqspi->dev, "failed to start RX DMA: %d\n", ret);
+			if (tqspi->cur_direction & DATA_DIR_TX)
+				dmaengine_terminate_all(tqspi->tx_dma_chan);
+			return ret;
+		}
+	}
+
+	tegra_qspi_writel(tqspi, tqspi->command1_reg, QSPI_COMMAND1);
+
+	tqspi->is_curr_dma_xfer = true;
+	tqspi->dma_control_reg = val;
+	val |= QSPI_DMA_EN;
+	tegra_qspi_writel(tqspi, val, QSPI_DMA_CTL);
+
+	return ret;
+}
+
+static int tegra_qspi_start_cpu_based_transfer(struct tegra_qspi *qspi, struct spi_transfer *t)
+{
+	u32 val;
+	unsigned int cur_words;
+
+	if (qspi->cur_direction & DATA_DIR_TX)
+		cur_words = tegra_qspi_fill_tx_fifo_from_client_txbuf(qspi, t);
+	else
+		cur_words = qspi->curr_dma_words;
+
+	val = QSPI_DMA_BLK_SET(cur_words - 1);
+	tegra_qspi_writel(qspi, val, QSPI_DMA_BLK);
+
+	tegra_qspi_unmask_irq(qspi);
+
+	qspi->is_curr_dma_xfer = false;
+	val = qspi->command1_reg;
+	val |= QSPI_PIO;
+	tegra_qspi_writel(qspi, val, QSPI_COMMAND1);
+
+	return 0;
+}
+
+static void tegra_qspi_deinit_dma(struct tegra_qspi *tqspi)
+{
+	if (tqspi->tx_dma_buf) {
+		dma_free_coherent(tqspi->dev, tqspi->dma_buf_size,
+				  tqspi->tx_dma_buf, tqspi->tx_dma_phys);
+		tqspi->tx_dma_buf = NULL;
+	}
+
+	if (tqspi->tx_dma_chan) {
+		dma_release_channel(tqspi->tx_dma_chan);
+		tqspi->tx_dma_chan = NULL;
+	}
+
+	if (tqspi->rx_dma_buf) {
+		dma_free_coherent(tqspi->dev, tqspi->dma_buf_size,
+				  tqspi->rx_dma_buf, tqspi->rx_dma_phys);
+		tqspi->rx_dma_buf = NULL;
+	}
+
+	if (tqspi->rx_dma_chan) {
+		dma_release_channel(tqspi->rx_dma_chan);
+		tqspi->rx_dma_chan = NULL;
+	}
+}
+
+static int tegra_qspi_init_dma(struct tegra_qspi *tqspi)
+{
+	struct dma_chan *dma_chan;
+	dma_addr_t dma_phys;
+	u32 *dma_buf;
+	int err;
+
+	dma_chan = dma_request_chan(tqspi->dev, "rx");
+	if (IS_ERR(dma_chan)) {
+		err = PTR_ERR(dma_chan);
+		goto err_out;
+	}
+
+	tqspi->rx_dma_chan = dma_chan;
+
+	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
+	if (!dma_buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	tqspi->rx_dma_buf = dma_buf;
+	tqspi->rx_dma_phys = dma_phys;
+
+	dma_chan = dma_request_chan(tqspi->dev, "tx");
+	if (IS_ERR(dma_chan)) {
+		err = PTR_ERR(dma_chan);
+		goto err_out;
+	}
+
+	tqspi->tx_dma_chan = dma_chan;
+
+	dma_buf = dma_alloc_coherent(tqspi->dev, tqspi->dma_buf_size, &dma_phys, GFP_KERNEL);
+	if (!dma_buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	tqspi->tx_dma_buf = dma_buf;
+	tqspi->tx_dma_phys = dma_phys;
+	tqspi->use_dma = true;
+
+	return 0;
+
+err_out:
+	tegra_qspi_deinit_dma(tqspi);
+
+	if (err != -EPROBE_DEFER) {
+		dev_err(tqspi->dev, "cannot use DMA: %d\n", err);
+		dev_err(tqspi->dev, "falling back to PIO\n");
+		return 0;
+	}
+
+	return err;
+}
+
+static u32 tegra_qspi_setup_transfer_one(struct spi_device *spi, struct spi_transfer *t,
+					 bool is_first_of_msg)
+{
+	struct tegra_qspi *tqspi = spi_master_get_devdata(spi->master);
+	struct tegra_qspi_client_data *cdata = spi->controller_data;
+	u32 command1, command2, speed = t->speed_hz;
+	u8 bits_per_word = t->bits_per_word;
+	u32 tx_tap = 0, rx_tap = 0;
+	int req_mode;
+
+	if (speed != tqspi->cur_speed) {
+		clk_set_rate(tqspi->clk, speed);
+		tqspi->cur_speed = speed;
+	}
+
+	tqspi->cur_pos = 0;
+	tqspi->cur_rx_pos = 0;
+	tqspi->cur_tx_pos = 0;
+	tqspi->curr_xfer = t;
+
+	if (is_first_of_msg) {
+		tegra_qspi_mask_clear_irq(tqspi);
+
+		command1 = tqspi->def_command1_reg;
+		command1 |= QSPI_BIT_LENGTH(bits_per_word - 1);
+
+		command1 &= ~QSPI_CONTROL_MODE_MASK;
+		req_mode = spi->mode & 0x3;
+		if (req_mode == SPI_MODE_3)
+			command1 |= QSPI_CONTROL_MODE_3;
+		else
+			command1 |= QSPI_CONTROL_MODE_0;
+
+		if (spi->mode & SPI_CS_HIGH)
+			command1 |= QSPI_CS_SW_VAL;
+		else
+			command1 &= ~QSPI_CS_SW_VAL;
+		tegra_qspi_writel(tqspi, command1, QSPI_COMMAND1);
+
+		if (cdata && cdata->tx_clk_tap_delay)
+			tx_tap = cdata->tx_clk_tap_delay;
+
+		if (cdata && cdata->rx_clk_tap_delay)
+			rx_tap = cdata->rx_clk_tap_delay;
+
+		command2 = QSPI_TX_TAP_DELAY(tx_tap) | QSPI_RX_TAP_DELAY(rx_tap);
+		if (command2 != tqspi->def_command2_reg)
+			tegra_qspi_writel(tqspi, command2, QSPI_COMMAND2);
+
+	} else {
+		command1 = tqspi->command1_reg;
+		command1 &= ~QSPI_BIT_LENGTH(~0);
+		command1 |= QSPI_BIT_LENGTH(bits_per_word - 1);
+	}
+
+	command1 &= ~QSPI_SDR_DDR_SEL;
+
+	return command1;
+}
+
+static int tegra_qspi_start_transfer_one(struct spi_device *spi,
+					 struct spi_transfer *t, u32 command1)
+{
+	struct tegra_qspi *tqspi = spi_master_get_devdata(spi->master);
+	unsigned int total_fifo_words;
+	u8 bus_width = 0;
+	int ret;
+
+	total_fifo_words = tegra_qspi_calculate_curr_xfer_param(tqspi, t);
+
+	command1 &= ~QSPI_PACKED;
+	if (tqspi->is_packed)
+		command1 |= QSPI_PACKED;
+	tegra_qspi_writel(tqspi, command1, QSPI_COMMAND1);
+
+	tqspi->cur_direction = 0;
+
+	command1 &= ~(QSPI_TX_EN | QSPI_RX_EN);
+	if (t->rx_buf) {
+		command1 |= QSPI_RX_EN;
+		tqspi->cur_direction |= DATA_DIR_RX;
+		bus_width = t->rx_nbits;
+	}
+
+	if (t->tx_buf) {
+		command1 |= QSPI_TX_EN;
+		tqspi->cur_direction |= DATA_DIR_TX;
+		bus_width = t->tx_nbits;
+	}
+
+	command1 &= ~QSPI_INTERFACE_WIDTH_MASK;
+
+	if (bus_width == SPI_NBITS_QUAD)
+		command1 |= QSPI_INTERFACE_WIDTH_QUAD;
+	else if (bus_width == SPI_NBITS_DUAL)
+		command1 |= QSPI_INTERFACE_WIDTH_DUAL;
+	else
+		command1 |= QSPI_INTERFACE_WIDTH_SINGLE;
+
+	tqspi->command1_reg = command1;
+
+	ret = tegra_qspi_flush_fifos(tqspi, false);
+	if (ret < 0)
+		return ret;
+
+	if (tqspi->use_dma && total_fifo_words > QSPI_FIFO_DEPTH)
+		ret = tegra_qspi_start_dma_based_transfer(tqspi, t);
+	else
+		ret = tegra_qspi_start_cpu_based_transfer(tqspi, t);
+
+	return ret;
+}
+
+static struct tegra_qspi_client_data *tegra_qspi_parse_cdata_dt(struct spi_device *spi)
+{
+	struct tegra_qspi_client_data *cdata;
+	struct device_node *slave_np = spi->dev.of_node;
+
+	cdata = kzalloc(sizeof(*cdata), GFP_KERNEL);
+	if (!cdata)
+		return NULL;
+
+	of_property_read_u32(slave_np, "nvidia,tx-clk-tap-delay",
+			     &cdata->tx_clk_tap_delay);
+	of_property_read_u32(slave_np, "nvidia,rx-clk-tap-delay",
+			     &cdata->rx_clk_tap_delay);
+	return cdata;
+}
+
+static void tegra_qspi_cleanup(struct spi_device *spi)
+{
+	struct tegra_qspi_client_data *cdata = spi->controller_data;
+
+	spi->controller_data = NULL;
+	kfree(cdata);
+}
+
+static int tegra_qspi_setup(struct spi_device *spi)
+{
+	struct tegra_qspi *tqspi = spi_master_get_devdata(spi->master);
+	struct tegra_qspi_client_data *cdata = spi->controller_data;
+	unsigned long flags;
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(tqspi->dev);
+	if (ret < 0) {
+		dev_err(tqspi->dev, "failed to get runtime PM: %d\n", ret);
+		return ret;
+	}
+
+	if (!cdata) {
+		cdata = tegra_qspi_parse_cdata_dt(spi);
+		spi->controller_data = cdata;
+	}
+
+	spin_lock_irqsave(&tqspi->lock, flags);
+
+	/* keep default cs state to inactive */
+	val = tqspi->def_command1_reg;
+	if (spi->mode & SPI_CS_HIGH)
+		val &= ~QSPI_CS_SW_VAL;
+	else
+		val |= QSPI_CS_SW_VAL;
+
+	tqspi->def_command1_reg = val;
+	tegra_qspi_writel(tqspi, tqspi->def_command1_reg, QSPI_COMMAND1);
+
+	spin_unlock_irqrestore(&tqspi->lock, flags);
+
+	pm_runtime_put(tqspi->dev);
+
+	return 0;
+}
+
+static void tegra_qspi_dump_regs(struct tegra_qspi *tqspi)
+{
+	dev_dbg(tqspi->dev, "============ QSPI REGISTER DUMP ============\n");
+	dev_dbg(tqspi->dev, "Command1:    0x%08x | Command2:    0x%08x\n",
+		tegra_qspi_readl(tqspi, QSPI_COMMAND1),
+		tegra_qspi_readl(tqspi, QSPI_COMMAND2));
+	dev_dbg(tqspi->dev, "DMA_CTL:     0x%08x | DMA_BLK:     0x%08x\n",
+		tegra_qspi_readl(tqspi, QSPI_DMA_CTL),
+		tegra_qspi_readl(tqspi, QSPI_DMA_BLK));
+	dev_dbg(tqspi->dev, "INTR_MASK:  0x%08x | MISC: 0x%08x\n",
+		tegra_qspi_readl(tqspi, QSPI_INTR_MASK),
+		tegra_qspi_readl(tqspi, QSPI_MISC_REG));
+	dev_dbg(tqspi->dev, "TRANS_STAT:  0x%08x | FIFO_STATUS: 0x%08x\n",
+		tegra_qspi_readl(tqspi, QSPI_TRANS_STATUS),
+		tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS));
+}
+
+static void tegra_qspi_handle_error(struct tegra_qspi *tqspi)
+{
+	dev_err(tqspi->dev, "error in transfer, fifo status 0x%08x\n", tqspi->status_reg);
+	tegra_qspi_dump_regs(tqspi);
+	tegra_qspi_flush_fifos(tqspi, true);
+	reset_control_assert(tqspi->rst);
+	udelay(2);
+	reset_control_deassert(tqspi->rst);
+}
+
+static void tegra_qspi_transfer_end(struct spi_device *spi)
+{
+	struct tegra_qspi *tqspi = spi_master_get_devdata(spi->master);
+	int cs_val = (spi->mode & SPI_CS_HIGH) ? 0 : 1;
+
+	if (cs_val)
+		tqspi->command1_reg |= QSPI_CS_SW_VAL;
+	else
+		tqspi->command1_reg &= ~QSPI_CS_SW_VAL;
+	tegra_qspi_writel(tqspi, tqspi->command1_reg, QSPI_COMMAND1);
+	tegra_qspi_writel(tqspi, tqspi->def_command1_reg, QSPI_COMMAND1);
+}
+
+static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi_message *msg)
+{
+	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
+	struct spi_device *spi = msg->spi;
+	struct spi_transfer *xfer;
+	bool is_first_msg = true;
+	int ret;
+
+	msg->status = 0;
+	msg->actual_length = 0;
+	tqspi->tx_status = 0;
+	tqspi->rx_status = 0;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		u32 cmd1;
+
+		reinit_completion(&tqspi->xfer_completion);
+
+		cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);
+
+		ret = tegra_qspi_start_transfer_one(spi, xfer, cmd1);
+		if (ret < 0) {
+			dev_err(tqspi->dev, "failed to start transfer: %d\n", ret);
+			goto complete_xfer;
+		}
+
+		is_first_msg = false;
+		ret = wait_for_completion_timeout(&tqspi->xfer_completion,
+						  QSPI_DMA_TIMEOUT);
+		if (WARN_ON(ret == 0)) {
+			dev_err(tqspi->dev, "transfer timeout: %d\n", ret);
+			if (tqspi->is_curr_dma_xfer && (tqspi->cur_direction & DATA_DIR_TX))
+				dmaengine_terminate_all(tqspi->tx_dma_chan);
+			if (tqspi->is_curr_dma_xfer && (tqspi->cur_direction & DATA_DIR_RX))
+				dmaengine_terminate_all(tqspi->rx_dma_chan);
+			tegra_qspi_handle_error(tqspi);
+			ret = -EIO;
+			goto complete_xfer;
+		}
+
+		if (tqspi->tx_status ||  tqspi->rx_status) {
+			tegra_qspi_handle_error(tqspi);
+			ret = -EIO;
+			goto complete_xfer;
+		}
+
+		msg->actual_length += xfer->len;
+
+complete_xfer:
+		if (ret < 0) {
+			tegra_qspi_transfer_end(spi);
+			spi_transfer_delay_exec(xfer);
+			goto exit;
+		}
+
+		if (list_is_last(&xfer->transfer_list, &msg->transfers)) {
+			/* de-activate CS after last transfer only when cs_change is not set */
+			if (!xfer->cs_change) {
+				tegra_qspi_transfer_end(spi);
+				spi_transfer_delay_exec(xfer);
+			}
+		} else if (xfer->cs_change) {
+			 /* de-activated CS between the transfers only when cs_change is set */
+			tegra_qspi_transfer_end(spi);
+			spi_transfer_delay_exec(xfer);
+		}
+	}
+
+	ret = 0;
+exit:
+	msg->status = ret;
+	spi_finalize_current_message(master);
+	return ret;
+}
+
+static irqreturn_t handle_cpu_based_xfer(struct tegra_qspi *tqspi)
+{
+	struct spi_transfer *t = tqspi->curr_xfer;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tqspi->lock, flags);
+
+	if (tqspi->tx_status ||  tqspi->rx_status) {
+		tegra_qspi_handle_error(tqspi);
+		complete(&tqspi->xfer_completion);
+		goto exit;
+	}
+
+	if (tqspi->cur_direction & DATA_DIR_RX)
+		tegra_qspi_read_rx_fifo_to_client_rxbuf(tqspi, t);
+
+	if (tqspi->cur_direction & DATA_DIR_TX)
+		tqspi->cur_pos = tqspi->cur_tx_pos;
+	else
+		tqspi->cur_pos = tqspi->cur_rx_pos;
+
+	if (tqspi->cur_pos == t->len) {
+		complete(&tqspi->xfer_completion);
+		goto exit;
+	}
+
+	tegra_qspi_calculate_curr_xfer_param(tqspi, t);
+	tegra_qspi_start_cpu_based_transfer(tqspi, t);
+exit:
+	spin_unlock_irqrestore(&tqspi->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t handle_dma_based_xfer(struct tegra_qspi *tqspi)
+{
+	struct spi_transfer *t = tqspi->curr_xfer;
+	unsigned int total_fifo_words;
+	unsigned long flags;
+	long wait_status;
+	int err = 0;
+
+	if (tqspi->cur_direction & DATA_DIR_TX) {
+		if (tqspi->tx_status) {
+			dmaengine_terminate_all(tqspi->tx_dma_chan);
+			err += 1;
+		} else {
+			wait_status = wait_for_completion_interruptible_timeout(
+				&tqspi->tx_dma_complete, QSPI_DMA_TIMEOUT);
+			if (wait_status <= 0) {
+				dmaengine_terminate_all(tqspi->tx_dma_chan);
+				dev_err(tqspi->dev, "failed TX DMA transfer\n");
+				err += 1;
+			}
+		}
+	}
+
+	if (tqspi->cur_direction & DATA_DIR_RX) {
+		if (tqspi->rx_status) {
+			dmaengine_terminate_all(tqspi->rx_dma_chan);
+			err += 2;
+		} else {
+			wait_status = wait_for_completion_interruptible_timeout(
+				&tqspi->rx_dma_complete, QSPI_DMA_TIMEOUT);
+			if (wait_status <= 0) {
+				dmaengine_terminate_all(tqspi->rx_dma_chan);
+				dev_err(tqspi->dev, "failed RX DMA transfer\n");
+				err += 2;
+			}
+		}
+	}
+
+	spin_lock_irqsave(&tqspi->lock, flags);
+
+	if (err) {
+		tegra_qspi_dma_unmap_xfer(tqspi, t);
+		tegra_qspi_handle_error(tqspi);
+		complete(&tqspi->xfer_completion);
+		goto exit;
+	}
+
+	if (tqspi->cur_direction & DATA_DIR_RX)
+		tegra_qspi_copy_qspi_rxbuf_to_client_rxbuf(tqspi, t);
+
+	if (tqspi->cur_direction & DATA_DIR_TX)
+		tqspi->cur_pos = tqspi->cur_tx_pos;
+	else
+		tqspi->cur_pos = tqspi->cur_rx_pos;
+
+	if (tqspi->cur_pos == t->len) {
+		tegra_qspi_dma_unmap_xfer(tqspi, t);
+		complete(&tqspi->xfer_completion);
+		goto exit;
+	}
+
+	tegra_qspi_dma_unmap_xfer(tqspi, t);
+
+	/* continue transfer in current message */
+	total_fifo_words = tegra_qspi_calculate_curr_xfer_param(tqspi, t);
+	if (total_fifo_words > QSPI_FIFO_DEPTH)
+		err = tegra_qspi_start_dma_based_transfer(tqspi, t);
+	else
+		err = tegra_qspi_start_cpu_based_transfer(tqspi, t);
+
+exit:
+	spin_unlock_irqrestore(&tqspi->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tegra_qspi_isr_thread(int irq, void *context_data)
+{
+	struct tegra_qspi *tqspi = context_data;
+
+	tqspi->status_reg = tegra_qspi_readl(tqspi, QSPI_FIFO_STATUS);
+
+	if (tqspi->cur_direction & DATA_DIR_TX)
+		tqspi->tx_status = tqspi->status_reg & (QSPI_TX_FIFO_UNF | QSPI_TX_FIFO_OVF);
+
+	if (tqspi->cur_direction & DATA_DIR_RX)
+		tqspi->rx_status = tqspi->status_reg & (QSPI_RX_FIFO_OVF | QSPI_RX_FIFO_UNF);
+
+	tegra_qspi_mask_clear_irq(tqspi);
+
+	if (!tqspi->is_curr_dma_xfer)
+		return handle_cpu_based_xfer(tqspi);
+
+	return handle_dma_based_xfer(tqspi);
+}
+
+static const struct of_device_id tegra_qspi_of_match[] = {
+	{ .compatible = "nvidia,tegra210-qspi", },
+	{ .compatible = "nvidia,tegra186-qspi", },
+	{ .compatible = "nvidia,tegra194-qspi", },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, tegra_qspi_of_match);
+
+static int tegra_qspi_probe(struct platform_device *pdev)
+{
+	struct spi_master	*master;
+	struct tegra_qspi	*tqspi;
+	struct resource		*r;
+	int ret, qspi_irq;
+	int bus_num;
+
+	master = devm_spi_alloc_master(&pdev->dev, sizeof(*tqspi));
+	if (!master) {
+		dev_err(&pdev->dev, "failed to allocate spi_master\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, master);
+	tqspi = spi_master_get_devdata(master);
+
+	master->mode_bits = SPI_MODE_0 | SPI_MODE_3 | SPI_CS_HIGH |
+			    SPI_TX_DUAL | SPI_RX_DUAL | SPI_TX_QUAD | SPI_RX_QUAD;
+	master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
+	master->setup = tegra_qspi_setup;
+	master->cleanup = tegra_qspi_cleanup;
+	master->transfer_one_message = tegra_qspi_transfer_one_message;
+	master->num_chipselect = 1;
+	master->auto_runtime_pm = true;
+
+	bus_num = of_alias_get_id(pdev->dev.of_node, "spi");
+	if (bus_num >= 0)
+		master->bus_num = bus_num;
+
+	tqspi->master = master;
+	tqspi->dev = &pdev->dev;
+	spin_lock_init(&tqspi->lock);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	tqspi->base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(tqspi->base))
+		return PTR_ERR(tqspi->base);
+
+	tqspi->phys = r->start;
+	qspi_irq = platform_get_irq(pdev, 0);
+	tqspi->irq = qspi_irq;
+
+	tqspi->clk = devm_clk_get(&pdev->dev, "qspi");
+	if (IS_ERR(tqspi->clk)) {
+		ret = PTR_ERR(tqspi->clk);
+		dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
+		return ret;
+	}
+
+	tqspi->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(tqspi->rst)) {
+		ret = PTR_ERR(tqspi->rst);
+		dev_err(&pdev->dev, "failed to get reset control: %d\n", ret);
+		return ret;
+	}
+
+	tqspi->max_buf_size = QSPI_FIFO_DEPTH << 2;
+	tqspi->dma_buf_size = DEFAULT_QSPI_DMA_BUF_LEN;
+
+	ret = tegra_qspi_init_dma(tqspi);
+	if (ret < 0)
+		return ret;
+
+	if (tqspi->use_dma)
+		tqspi->max_buf_size = tqspi->dma_buf_size;
+
+	init_completion(&tqspi->tx_dma_complete);
+	init_completion(&tqspi->rx_dma_complete);
+	init_completion(&tqspi->xfer_completion);
+
+	pm_runtime_enable(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get runtime PM: %d\n", ret);
+		goto exit_pm_disable;
+	}
+
+	reset_control_assert(tqspi->rst);
+	udelay(2);
+	reset_control_deassert(tqspi->rst);
+
+	tqspi->def_command1_reg = QSPI_M_S | QSPI_CS_SW_HW |  QSPI_CS_SW_VAL;
+	tegra_qspi_writel(tqspi, tqspi->def_command1_reg, QSPI_COMMAND1);
+	tqspi->spi_cs_timing1 = tegra_qspi_readl(tqspi, QSPI_CS_TIMING1);
+	tqspi->spi_cs_timing2 = tegra_qspi_readl(tqspi, QSPI_CS_TIMING2);
+	tqspi->def_command2_reg = tegra_qspi_readl(tqspi, QSPI_COMMAND2);
+
+	pm_runtime_put(&pdev->dev);
+
+	ret = request_threaded_irq(tqspi->irq, NULL,
+				   tegra_qspi_isr_thread, IRQF_ONESHOT,
+				   dev_name(&pdev->dev), tqspi);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n", tqspi->irq, ret);
+		goto exit_pm_disable;
+	}
+
+	master->dev.of_node = pdev->dev.of_node;
+	ret = spi_register_master(master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to register master: %d\n", ret);
+		goto exit_free_irq;
+	}
+
+	return 0;
+
+exit_free_irq:
+	free_irq(qspi_irq, tqspi);
+exit_pm_disable:
+	pm_runtime_disable(&pdev->dev);
+	tegra_qspi_deinit_dma(tqspi);
+	return ret;
+}
+
+static int tegra_qspi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
+
+	spi_unregister_master(master);
+	free_irq(tqspi->irq, tqspi);
+	tegra_qspi_deinit_dma(tqspi);
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int tegra_qspi_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+
+	return spi_master_suspend(master);
+}
+
+static int tegra_qspi_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		dev_err(dev, "failed to get runtime PM: %d\n", ret);
+		return ret;
+	}
+
+	tegra_qspi_writel(tqspi, tqspi->command1_reg, QSPI_COMMAND1);
+	tegra_qspi_writel(tqspi, tqspi->def_command2_reg, QSPI_COMMAND2);
+	pm_runtime_put(dev);
+
+	return spi_master_resume(master);
+}
+#endif
+
+static int tegra_qspi_runtime_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
+
+	/* flush all write which are in PPSB queue by reading back */
+	tegra_qspi_readl(tqspi, QSPI_COMMAND1);
+
+	clk_disable_unprepare(tqspi->clk);
+
+	return 0;
+}
+
+static int tegra_qspi_runtime_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(tqspi->clk);
+	if (ret < 0)
+		dev_err(tqspi->dev, "failed to enable clock: %d\n", ret);
+
+	return ret;
+}
+
+static const struct dev_pm_ops tegra_qspi_pm_ops = {
+	SET_RUNTIME_PM_OPS(tegra_qspi_runtime_suspend, tegra_qspi_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(tegra_qspi_suspend, tegra_qspi_resume)
+};
+
+static struct platform_driver tegra_qspi_driver = {
+	.driver = {
+		.name		= "tegra-qspi",
+		.pm		= &tegra_qspi_pm_ops,
+		.of_match_table	= tegra_qspi_of_match,
+	},
+	.probe =	tegra_qspi_probe,
+	.remove =	tegra_qspi_remove,
+};
+module_platform_driver(tegra_qspi_driver);
+
+MODULE_ALIAS("platform:qspi-tegra");
+MODULE_DESCRIPTION("NVIDIA Tegra QSPI Controller Driver");
+MODULE_AUTHOR("Sowjanya Komatineni <skomatineni@nvidia.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

[PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Sowjanya Komatineni]

This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
that support transfer of dummy cycles by the hardware directly.

For controller with this flag set, spi-mem driver will skip dummy bytes
transfer in the spi message.

Controller drivers can get the number of dummy cycles from spi_message.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 drivers/spi/spi-mem.c   | 18 +++++++++++-------
 include/linux/spi/spi.h |  8 ++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index f3a3f19..38a523b 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	}
 
 	if (op->dummy.nbytes) {
-		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
-		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
-		xfers[xferpos].len = op->dummy.nbytes;
-		xfers[xferpos].tx_nbits = op->dummy.buswidth;
-		spi_message_add_tail(&xfers[xferpos], &msg);
-		xferpos++;
-		totalxferlen += op->dummy.nbytes;
+		if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
+			msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
+		} else {
+			memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
+			xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
+			xfers[xferpos].len = op->dummy.nbytes;
+			xfers[xferpos].tx_nbits = op->dummy.buswidth;
+			spi_message_add_tail(&xfers[xferpos], &msg);
+			xferpos++;
+			totalxferlen += op->dummy.nbytes;
+		}
 	}
 
 	if (op->data.nbytes) {
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index aa09fdc..2024149 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -512,6 +512,8 @@ struct spi_controller {
 
 #define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must select slave */
 
+#define SPI_MASTER_USES_HW_DUMMY_CYCLES	BIT(6)	/* HW dummy bytes transfer */
+
 	/* flag indicating this is an SPI slave controller */
 	bool			slave;
 
@@ -1022,6 +1024,12 @@ struct spi_message {
 	unsigned		actual_length;
 	int			status;
 
+	/*
+	 * dummy cycles in the message transfer. This is used by the controller
+	 * drivers supports transfer of dummy cycles directly by the hardware.
+	 */
+	u8			dummy_cycles;
+
 	/* for optional use by whatever driver currently owns the
 	 * spi_message ...  between calls to spi_async and then later
 	 * complete(), that's the spi_controller controller driver.
-- 
2.7.4

[PATCH v3 6/9] spi: tegra210-quad: Add support for hardware dummy cycles

[Sowjanya Komatineni]

Tegra Quad SPI controller hardware supports sending dummy cycles
after address bytes.

This patch adds this support.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 drivers/spi/spi-tegra210-quad.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
index 624f395..1d1b125 100644
--- a/drivers/spi/spi-tegra210-quad.c
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -124,6 +124,13 @@
 #define QSPI_DMA_TIMEOUT			(msecs_to_jiffies(1000))
 #define DEFAULT_QSPI_DMA_BUF_LEN		(64 * 1024)
 
+enum transfer_phase {
+	CMD_BYTE_XFER = 0,
+	ADDR_BYTES_XFER,
+	DATA_BYTES_XFER,
+	MAX_XFERS,
+};
+
 struct tegra_qspi_client_data {
 	int tx_clk_tap_delay;
 	int rx_clk_tap_delay;
@@ -857,6 +864,8 @@ static int tegra_qspi_start_transfer_one(struct spi_device *spi,
 
 	tqspi->command1_reg = command1;
 
+	tegra_qspi_writel(tqspi, QSPI_NUM_DUMMY_CYCLE(tqspi->dummy_cycles), QSPI_MISC_REG);
+
 	ret = tegra_qspi_flush_fifos(tqspi, false);
 	if (ret < 0)
 		return ret;
@@ -977,7 +986,7 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
 	struct spi_device *spi = msg->spi;
 	struct spi_transfer *xfer;
 	bool is_first_msg = true;
-	int ret;
+	int ret, xfer_phase = 0;
 
 	msg->status = 0;
 	msg->actual_length = 0;
@@ -987,6 +996,15 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 		u32 cmd1;
 
+		/*
+		 * Program dummy clock cycles in Tegra QSPI register only
+		 * during address transfer phase.
+		 */
+		if (xfer_phase == ADDR_BYTES_XFER)
+			tqspi->dummy_cycles = msg->dummy_cycles;
+		else
+			tqspi->dummy_cycles = 0;
+
 		reinit_completion(&tqspi->xfer_completion);
 
 		cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);
@@ -1018,6 +1036,7 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
 		}
 
 		msg->actual_length += xfer->len;
+		xfer_phase++;
 
 complete_xfer:
 		if (ret < 0) {
@@ -1203,6 +1222,7 @@ static int tegra_qspi_probe(struct platform_device *pdev)
 	master->mode_bits = SPI_MODE_0 | SPI_MODE_3 | SPI_CS_HIGH |
 			    SPI_TX_DUAL | SPI_RX_DUAL | SPI_TX_QUAD | SPI_RX_QUAD;
 	master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
+	master->flags = SPI_MASTER_USES_HW_DUMMY_CYCLES;
 	master->setup = tegra_qspi_setup;
 	master->cleanup = tegra_qspi_cleanup;
 	master->transfer_one_message = tegra_qspi_transfer_one_message;
-- 
2.7.4

[PATCH v3 7/9] arm64: tegra: Enable QSPI on Jetson Nano

[Sowjanya Komatineni]

This patch enables QSPI on Jetson Nano.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts | 12 ++++++++++++
 arch/arm64/boot/dts/nvidia/tegra210.dtsi           |  5 +++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts b/arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts
index 6a877de..a1b4603 100644
--- a/arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts
+++ b/arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts
@@ -638,6 +638,18 @@
 		};
 	};
 
+	spi@70410000 {
+		status = "okay";
+
+		flash@0 {
+			compatible = "spi-nor";
+			reg = <0>;
+			spi-max-frequency = <104000000>;
+			spi-tx-bus-width = <2>;
+			spi-rx-bus-width = <2>;
+		};
+	};
+
 	clk32k_in: clock@0 {
 		compatible = "fixed-clock";
 		clock-frequency = <32768>;
diff --git a/arch/arm64/boot/dts/nvidia/tegra210.dtsi b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
index 4fbf8c1..998fa81 100644
--- a/arch/arm64/boot/dts/nvidia/tegra210.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
@@ -1536,8 +1536,9 @@
 		interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>;
 		#address-cells = <1>;
 		#size-cells = <0>;
-		clocks = <&tegra_car TEGRA210_CLK_QSPI>;
-		clock-names = "qspi";
+		clocks = <&tegra_car TEGRA210_CLK_QSPI>,
+			 <&tegra_car TEGRA210_CLK_QSPI_PM>;
+		clock-names = "qspi", "qspi_out";
 		resets = <&tegra_car 211>;
 		reset-names = "qspi";
 		dmas = <&apbdma 5>, <&apbdma 5>;
-- 
2.7.4

[PATCH v3 8/9] arm64: tegra: Add QSPI nodes on Tegra194

[Sowjanya Komatineni]

Tegra194 has 2 QSPI controllers.

This patch adds DT node for these 2 QSPI controllers.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra194.dtsi | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
index 25f36d6..63ed788 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
@@ -609,6 +609,30 @@
 			status = "disabled";
 		};
 
+		spi@3270000 {
+			compatible = "nvidia,tegra194-qspi";
+			reg = <0x3270000 0x1000>;
+			interrupts = <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&bpmp TEGRA194_CLK_QSPI0>,
+				 <&bpmp TEGRA194_CLK_QSPI0_PM>;
+			clock-names = "qspi", "qspi_out";
+			resets = <&bpmp TEGRA194_RESET_QSPI0>;
+			reset-names = "qspi";
+			status = "disabled";
+		};
+
+		spi@3300000 {
+			compatible = "nvidia,tegra194-qspi";
+			reg = <0x3300000 0x1000>;
+			interrupts = <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&bpmp TEGRA194_CLK_QSPI1>,
+				 <&bpmp TEGRA194_CLK_QSPI1_PM>;
+			clock-names = "qspi", "qspi_out";
+			resets = <&bpmp TEGRA194_RESET_QSPI1>;
+			reset-names = "qspi";
+			status = "disabled";
+		};
+
 		pwm1: pwm@3280000 {
 			compatible = "nvidia,tegra194-pwm",
 				     "nvidia,tegra186-pwm";
-- 
2.7.4

[PATCH v3 9/9] arm64: tegra: Enable QSPI on Jetson Xavier NX

[Sowjanya Komatineni]

This patch enables QSPI on Jetson Xavier NX.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
 .../arm64/boot/dts/nvidia/tegra194-p3509-0000+p3668-0000.dts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm64/boot/dts/nvidia/tegra194-p3509-0000+p3668-0000.dts b/arch/arm64/boot/dts/nvidia/tegra194-p3509-0000+p3668-0000.dts
index 7f97b34..f1053e7 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194-p3509-0000+p3668-0000.dts
+++ b/arch/arm64/boot/dts/nvidia/tegra194-p3509-0000+p3668-0000.dts
@@ -100,6 +100,18 @@
 			phy-names = "usb2-1", "usb2-2", "usb3-2";
 		};
 
+		spi@3270000 {
+			status = "okay";
+
+			flash@0 {
+				compatible = "spi-nor";
+				reg = <0>;
+				spi-max-frequency = <102000000>;
+				spi-tx-bus-width = <4>;
+				spi-rx-bus-width = <4>;
+			};
+		};
+
 		pwm@32d0000 {
 			status = "okay";
 		};
-- 
2.7.4

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Boris Brezillon]

On Fri, 11 Dec 2020 13:15:59 -0800
Sowjanya Komatineni <skomatineni@nvidia.com> wrote:

> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
> that support transfer of dummy cycles by the hardware directly.

Hm, not sure this is a good idea. I mean, if we expect regular SPI
devices to use this feature, then why not, but if it's just for
spi-mem, I'd recommend implementing a driver-specific exec_op() instead
of using the default one.

If we go for those core changes, we should at least add a
ctrl->max_dummy_cycles field so the core can fallback to regular writes
when the number of dummy cycles in the spi_mem_op exceeds what the
controller can do.

> 
> For controller with this flag set, spi-mem driver will skip dummy bytes
> transfer in the spi message.
> 
> Controller drivers can get the number of dummy cycles from spi_message.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
>  drivers/spi/spi-mem.c   | 18 +++++++++++-------
>  include/linux/spi/spi.h |  8 ++++++++
>  2 files changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index f3a3f19..38a523b 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>  	}
>  
>  	if (op->dummy.nbytes) {
> -		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> -		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> -		xfers[xferpos].len = op->dummy.nbytes;
> -		xfers[xferpos].tx_nbits = op->dummy.buswidth;
> -		spi_message_add_tail(&xfers[xferpos], &msg);
> -		xferpos++;
> -		totalxferlen += op->dummy.nbytes;
> +		if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
> +			msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
> +		} else {
> +			memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> +			xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> +			xfers[xferpos].len = op->dummy.nbytes;
> +			xfers[xferpos].tx_nbits = op->dummy.buswidth;
> +			spi_message_add_tail(&xfers[xferpos], &msg);
> +			xferpos++;
> +			totalxferlen += op->dummy.nbytes;
> +		}
>  	}
>  
>  	if (op->data.nbytes) {
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index aa09fdc..2024149 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -512,6 +512,8 @@ struct spi_controller {
>  
>  #define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must select slave */
>  
> +#define SPI_MASTER_USES_HW_DUMMY_CYCLES	BIT(6)	/* HW dummy bytes transfer */
> +
>  	/* flag indicating this is an SPI slave controller */
>  	bool			slave;
>  
> @@ -1022,6 +1024,12 @@ struct spi_message {
>  	unsigned		actual_length;
>  	int			status;
>  
> +	/*
> +	 * dummy cycles in the message transfer. This is used by the controller
> +	 * drivers supports transfer of dummy cycles directly by the hardware.
> +	 */
> +	u8			dummy_cycles;
> +
>  	/* for optional use by whatever driver currently owns the
>  	 * spi_message ...  between calls to spi_async and then later
>  	 * complete(), that's the spi_controller controller driver.

Re: [PATCH v3 4/9] spi: tegra210-quad: Add support for Tegra210 QSPI controller

[Lukas Wunner]

On Fri, Dec 11, 2020 at 01:15:58PM -0800, Sowjanya Komatineni wrote:
> Tegra SoC has a Quad SPI controller starting from Tegra210.

The probe/remove hooks LGTM now.  Just two tiny nits that caught my eye:


> +	master = devm_spi_alloc_master(&pdev->dev, sizeof(*tqspi));
> +	if (!master) {
> +		dev_err(&pdev->dev, "failed to allocate spi_master\n");
> +		return -ENOMEM;
> +	}

The memory allocater already emits an error message if it can't satisfy
a request.  Emitting an additional message here isn't really necessary.


> +exit_free_irq:
> +	free_irq(qspi_irq, tqspi);
> +exit_pm_disable:
> +	pm_runtime_disable(&pdev->dev);
> +	tegra_qspi_deinit_dma(tqspi);
> +	return ret;
> +}
> +
> +static int tegra_qspi_remove(struct platform_device *pdev)
> +{
> +	struct spi_master *master = platform_get_drvdata(pdev);
> +	struct tegra_qspi *tqspi = spi_master_get_devdata(master);
> +
> +	spi_unregister_master(master);
> +	free_irq(tqspi->irq, tqspi);
> +	tegra_qspi_deinit_dma(tqspi);
> +	pm_runtime_disable(&pdev->dev);

The order of tegra_qspi_deinit_dma() and pm_runtime_disable() is
reversed in the remove hook vis-a-vis the probe error path.
It's nicer to use the same order as in the probe error path.

Thanks,

Lukas

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Sowjanya Komatineni]

On 12/12/20 2:57 AM, Boris Brezillon wrote:
> On Fri, 11 Dec 2020 13:15:59 -0800
> Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
>
>> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
>> that support transfer of dummy cycles by the hardware directly.
> Hm, not sure this is a good idea. I mean, if we expect regular SPI
> devices to use this feature, then why not, but if it's just for
> spi-mem, I'd recommend implementing a driver-specific exec_op() instead
> of using the default one.

dummy cycles programming is SPI device specific.

Transfer of dummy bytes by SW or HW controller can be depending on 
features supported by controller.

Adding controller driver specific exec_op() Just for skipping dummy 
bytes transfer will have so much of redundant code pretty much what all 
spi_mem_exec_op does.

So in v1, I handled this in controller driver by skipping SW transfer of 
dummy bytes during dummy phase and programming dummy cycles in 
controller register to allow HW to transfer.

Based on v1 feedback discussion, added this flag 
SPI_MASTER_USES_HW_DUMMY_CYCLES which can be used by controllers 
supporting HW dummy bytes transfer and updated spi_mem_exec_op to skip 
SW dummy bytes.

This helps other controllers supporting HW transfer of dummy bytes as 
well just to set the flag and use dummy cycles directly.

> If we go for those core changes, we should at least add a
> ctrl->max_dummy_cycles field so the core can fallback to regular writes
> when the number of dummy cycles in the spi_mem_op exceeds what the
> controller can do.
Yes makes sense. Will add this once we decide on keeping this flag to 
identify controllers supporting HW transfer of dummy bytes Vs SW transfer.
>> For controller with this flag set, spi-mem driver will skip dummy bytes
>> transfer in the spi message.
>>
>> Controller drivers can get the number of dummy cycles from spi_message.
>>
>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>> ---
>>   drivers/spi/spi-mem.c   | 18 +++++++++++-------
>>   include/linux/spi/spi.h |  8 ++++++++
>>   2 files changed, 19 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index f3a3f19..38a523b 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>>   	}
>>   
>>   	if (op->dummy.nbytes) {
>> -		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
>> -		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
>> -		xfers[xferpos].len = op->dummy.nbytes;
>> -		xfers[xferpos].tx_nbits = op->dummy.buswidth;
>> -		spi_message_add_tail(&xfers[xferpos], &msg);
>> -		xferpos++;
>> -		totalxferlen += op->dummy.nbytes;
>> +		if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
>> +			msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
>> +		} else {
>> +			memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
>> +			xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
>> +			xfers[xferpos].len = op->dummy.nbytes;
>> +			xfers[xferpos].tx_nbits = op->dummy.buswidth;
>> +			spi_message_add_tail(&xfers[xferpos], &msg);
>> +			xferpos++;
>> +			totalxferlen += op->dummy.nbytes;
>> +		}
>>   	}
>>   
>>   	if (op->data.nbytes) {
>> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
>> index aa09fdc..2024149 100644
>> --- a/include/linux/spi/spi.h
>> +++ b/include/linux/spi/spi.h
>> @@ -512,6 +512,8 @@ struct spi_controller {
>>   
>>   #define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must select slave */
>>   
>> +#define SPI_MASTER_USES_HW_DUMMY_CYCLES	BIT(6)	/* HW dummy bytes transfer */
>> +
>>   	/* flag indicating this is an SPI slave controller */
>>   	bool			slave;
>>   
>> @@ -1022,6 +1024,12 @@ struct spi_message {
>>   	unsigned		actual_length;
>>   	int			status;
>>   
>> +	/*
>> +	 * dummy cycles in the message transfer. This is used by the controller
>> +	 * drivers supports transfer of dummy cycles directly by the hardware.
>> +	 */
>> +	u8			dummy_cycles;
>> +
>>   	/* for optional use by whatever driver currently owns the
>>   	 * spi_message ...  between calls to spi_async and then later
>>   	 * complete(), that's the spi_controller controller driver.

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Boris Brezillon]

On Sat, 12 Dec 2020 09:28:50 -0800
Sowjanya Komatineni <skomatineni@nvidia.com> wrote:

> On 12/12/20 2:57 AM, Boris Brezillon wrote:
> > On Fri, 11 Dec 2020 13:15:59 -0800
> > Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
> >  
> >> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
> >> that support transfer of dummy cycles by the hardware directly.  
> > Hm, not sure this is a good idea. I mean, if we expect regular SPI
> > devices to use this feature, then why not, but if it's just for
> > spi-mem, I'd recommend implementing a driver-specific exec_op() instead
> > of using the default one.  
> 
> dummy cycles programming is SPI device specific.
> 
> Transfer of dummy bytes by SW or HW controller can be depending on 
> features supported by controller.
> 
> Adding controller driver specific exec_op() Just for skipping dummy 
> bytes transfer will have so much of redundant code pretty much what all 
> spi_mem_exec_op does.
> 
> So in v1, I handled this in controller driver by skipping SW transfer of 
> dummy bytes during dummy phase and programming dummy cycles in 
> controller register to allow HW to transfer.
> 
> Based on v1 feedback discussion, added this flag 
> SPI_MASTER_USES_HW_DUMMY_CYCLES which can be used by controllers 
> supporting HW dummy bytes transfer and updated spi_mem_exec_op to skip 
> SW dummy bytes.
> 
> This helps other controllers supporting HW transfer of dummy bytes as 
> well just to set the flag and use dummy cycles directly.

Except saying a spi_message has X dummy cycle is not precise enough.
Where are those dummy cycles in the transfer sequence? spi-mem has well
defined sequencing (cmd[+addr][+dummy][+data]) so we know exacly where
dummy cycles are, but trying to retro-fit the dummy-cycle concept in
the generic spi_message is confusing IMHO. If want to avoid code
duplication, I'm pretty sure the driver can be reworked so the
spi_transfer/exec_op() path can share most of the logic (that probably
implies declaring a tegra_qspi_op).

> 
> > If we go for those core changes, we should at least add a
> > ctrl->max_dummy_cycles field so the core can fallback to regular writes
> > when the number of dummy cycles in the spi_mem_op exceeds what the
> > controller can do.  
> Yes makes sense. Will add this once we decide on keeping this flag to 
> identify controllers supporting HW transfer of dummy bytes Vs SW transfer.
> >> For controller with this flag set, spi-mem driver will skip dummy bytes
> >> transfer in the spi message.
> >>
> >> Controller drivers can get the number of dummy cycles from spi_message.
> >>
> >> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> >> ---
> >>   drivers/spi/spi-mem.c   | 18 +++++++++++-------
> >>   include/linux/spi/spi.h |  8 ++++++++
> >>   2 files changed, 19 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> >> index f3a3f19..38a523b 100644
> >> --- a/drivers/spi/spi-mem.c
> >> +++ b/drivers/spi/spi-mem.c
> >> @@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> >>   	}
> >>   
> >>   	if (op->dummy.nbytes) {
> >> -		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> >> -		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> >> -		xfers[xferpos].len = op->dummy.nbytes;
> >> -		xfers[xferpos].tx_nbits = op->dummy.buswidth;
> >> -		spi_message_add_tail(&xfers[xferpos], &msg);
> >> -		xferpos++;
> >> -		totalxferlen += op->dummy.nbytes;
> >> +		if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
> >> +			msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
> >> +		} else {
> >> +			memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> >> +			xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> >> +			xfers[xferpos].len = op->dummy.nbytes;
> >> +			xfers[xferpos].tx_nbits = op->dummy.buswidth;
> >> +			spi_message_add_tail(&xfers[xferpos], &msg);
> >> +			xferpos++;
> >> +			totalxferlen += op->dummy.nbytes;
> >> +		}
> >>   	}
> >>   
> >>   	if (op->data.nbytes) {
> >> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> >> index aa09fdc..2024149 100644
> >> --- a/include/linux/spi/spi.h
> >> +++ b/include/linux/spi/spi.h
> >> @@ -512,6 +512,8 @@ struct spi_controller {
> >>   
> >>   #define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must select slave */
> >>   
> >> +#define SPI_MASTER_USES_HW_DUMMY_CYCLES	BIT(6)	/* HW dummy bytes transfer */
> >> +
> >>   	/* flag indicating this is an SPI slave controller */
> >>   	bool			slave;
> >>   
> >> @@ -1022,6 +1024,12 @@ struct spi_message {
> >>   	unsigned		actual_length;
> >>   	int			status;
> >>   
> >> +	/*
> >> +	 * dummy cycles in the message transfer. This is used by the controller
> >> +	 * drivers supports transfer of dummy cycles directly by the hardware.
> >> +	 */
> >> +	u8			dummy_cycles;
> >> +
> >>   	/* for optional use by whatever driver currently owns the
> >>   	 * spi_message ...  between calls to spi_async and then later
> >>   	 * complete(), that's the spi_controller controller driver.  

Re: [PATCH v3 6/9] spi: tegra210-quad: Add support for hardware dummy cycles

[Boris Brezillon]

On Fri, 11 Dec 2020 13:16:00 -0800
Sowjanya Komatineni <skomatineni@nvidia.com> wrote:

> Tegra Quad SPI controller hardware supports sending dummy cycles
> after address bytes.
> 
> This patch adds this support.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
>  drivers/spi/spi-tegra210-quad.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
> index 624f395..1d1b125 100644
> --- a/drivers/spi/spi-tegra210-quad.c
> +++ b/drivers/spi/spi-tegra210-quad.c
> @@ -124,6 +124,13 @@
>  #define QSPI_DMA_TIMEOUT			(msecs_to_jiffies(1000))
>  #define DEFAULT_QSPI_DMA_BUF_LEN		(64 * 1024)
>  
> +enum transfer_phase {
> +	CMD_BYTE_XFER = 0,
> +	ADDR_BYTES_XFER,
> +	DATA_BYTES_XFER,
> +	MAX_XFERS,
> +};
> +
>  struct tegra_qspi_client_data {
>  	int tx_clk_tap_delay;
>  	int rx_clk_tap_delay;
> @@ -857,6 +864,8 @@ static int tegra_qspi_start_transfer_one(struct spi_device *spi,
>  
>  	tqspi->command1_reg = command1;
>  
> +	tegra_qspi_writel(tqspi, QSPI_NUM_DUMMY_CYCLE(tqspi->dummy_cycles), QSPI_MISC_REG);
> +
>  	ret = tegra_qspi_flush_fifos(tqspi, false);
>  	if (ret < 0)
>  		return ret;
> @@ -977,7 +986,7 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
>  	struct spi_device *spi = msg->spi;
>  	struct spi_transfer *xfer;
>  	bool is_first_msg = true;
> -	int ret;
> +	int ret, xfer_phase = 0;
>  
>  	msg->status = 0;
>  	msg->actual_length = 0;
> @@ -987,6 +996,15 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
>  	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
>  		u32 cmd1;
>  
> +		/*
> +		 * Program dummy clock cycles in Tegra QSPI register only
> +		 * during address transfer phase.
> +		 */
> +		if (xfer_phase == ADDR_BYTES_XFER)
> +			tqspi->dummy_cycles = msg->dummy_cycles;
> +		else
> +			tqspi->dummy_cycles = 0;

That's fragile. You're trying to guess the phase (which is clearly a
spi-mem concept) from the position of the transfer in the list. What
happens if a spi-mem operation has no address bytes but requires dummy
cycles after the command? What happens if we patch spi_mem_exec_op() to
merge the cmd and address bytes in a single transfer (that's an option
I considered at some point when designing the framework before deciding
it was not worth the extra complexity)?

Besides, I keep thinking the regular transfer path should not assume
it's being passed spi-mem operations, if it is, that means you should
overload the default exec_op(). The more I look at it the less I like
this idea of adding a dummy_cycles field to spi_message. I'm pretty
sure we can find other ways to avoid code duplication if that's your
main concern.

> +
>  		reinit_completion(&tqspi->xfer_completion);
>  
>  		cmd1 = tegra_qspi_setup_transfer_one(spi, xfer, is_first_msg);
> @@ -1018,6 +1036,7 @@ static int tegra_qspi_transfer_one_message(struct spi_master *master, struct spi
>  		}
>  
>  		msg->actual_length += xfer->len;
> +		xfer_phase++;
>  
>  complete_xfer:
>  		if (ret < 0) {
> @@ -1203,6 +1222,7 @@ static int tegra_qspi_probe(struct platform_device *pdev)
>  	master->mode_bits = SPI_MODE_0 | SPI_MODE_3 | SPI_CS_HIGH |
>  			    SPI_TX_DUAL | SPI_RX_DUAL | SPI_TX_QUAD | SPI_RX_QUAD;
>  	master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
> +	master->flags = SPI_MASTER_USES_HW_DUMMY_CYCLES;
>  	master->setup = tegra_qspi_setup;
>  	master->cleanup = tegra_qspi_cleanup;
>  	master->transfer_one_message = tegra_qspi_transfer_one_message;

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Boris Brezillon]

On Sun, 13 Dec 2020 10:54:26 +0100
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> On Sat, 12 Dec 2020 09:28:50 -0800
> Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
> 
> > On 12/12/20 2:57 AM, Boris Brezillon wrote:  
> > > On Fri, 11 Dec 2020 13:15:59 -0800
> > > Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
> > >    
> > >> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
> > >> that support transfer of dummy cycles by the hardware directly.    
> > > Hm, not sure this is a good idea. I mean, if we expect regular SPI
> > > devices to use this feature, then why not, but if it's just for
> > > spi-mem, I'd recommend implementing a driver-specific exec_op() instead
> > > of using the default one.    
> > 
> > dummy cycles programming is SPI device specific.
> > 
> > Transfer of dummy bytes by SW or HW controller can be depending on 
> > features supported by controller.
> > 
> > Adding controller driver specific exec_op() Just for skipping dummy 
> > bytes transfer will have so much of redundant code pretty much what all 
> > spi_mem_exec_op does.
> > 
> > So in v1, I handled this in controller driver by skipping SW transfer of 
> > dummy bytes during dummy phase and programming dummy cycles in 
> > controller register to allow HW to transfer.
> > 
> > Based on v1 feedback discussion, added this flag 
> > SPI_MASTER_USES_HW_DUMMY_CYCLES which can be used by controllers 
> > supporting HW dummy bytes transfer and updated spi_mem_exec_op to skip 
> > SW dummy bytes.
> > 
> > This helps other controllers supporting HW transfer of dummy bytes as 
> > well just to set the flag and use dummy cycles directly.  
> 
> Except saying a spi_message has X dummy cycle is not precise enough.
> Where are those dummy cycles in the transfer sequence? spi-mem has well
> defined sequencing (cmd[+addr][+dummy][+data]) so we know exacly where
> dummy cycles are, but trying to retro-fit the dummy-cycle concept in
> the generic spi_message is confusing IMHO. If want to avoid code
> duplication, I'm pretty sure the driver can be reworked so the
> spi_transfer/exec_op() path can share most of the logic (that probably
> implies declaring a tegra_qspi_op).

Something like that might also do the trick:

--->8---

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index ef53290b7d24..8b0476f37fbb 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -353,6 +353,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
                xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
                xfers[xferpos].len = op->dummy.nbytes;
                xfers[xferpos].tx_nbits = op->dummy.buswidth;
+               xfers[xferpos].dummy_data = 1;
                spi_message_add_tail(&xfers[xferpos], &msg);
                xferpos++;
                totalxferlen += op->dummy.nbytes;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 99380c0825db..ecf7989318c5 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -807,6 +807,10 @@ extern void spi_res_release(struct spi_controller *ctlr,
  *      transfer. If 0 the default (from @spi_device) is used.
  * @bits_per_word: select a bits_per_word other than the device default
  *      for this transfer. If 0 the default (from @spi_device) is used.
+ * @dummy_data: set to 1 for a dummy transfer (a transfer whose data is
+ *      ignored). Controllers that are able to issue dummy cycles can ignore
+ *      tx_buf, for those that can't tx_buf will contain dummy bytes. The
+ *      number of  dummy cycles to issue is (len * tx_bits) / 8.
  * @cs_change: affects chipselect after this transfer completes
  * @cs_change_delay: delay between cs deassert and assert when
  *      @cs_change is set and @spi_transfer is not the last in @spi_message
@@ -919,6 +923,7 @@ struct spi_transfer {
        struct sg_table tx_sg;
        struct sg_table rx_sg;
 
+       unsigned        dummy_data:1;
        unsigned        cs_change:1;
        unsigned        tx_nbits:3;
        unsigned        rx_nbits:3;

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Sowjanya Komatineni]

On 12/13/20 3:28 AM, Boris Brezillon wrote:
> On Sun, 13 Dec 2020 10:54:26 +0100
> Boris Brezillon <boris.brezillon@collabora.com> wrote:
>
>> On Sat, 12 Dec 2020 09:28:50 -0800
>> Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
>>
>>> On 12/12/20 2:57 AM, Boris Brezillon wrote:
>>>> On Fri, 11 Dec 2020 13:15:59 -0800
>>>> Sowjanya Komatineni <skomatineni@nvidia.com> wrote:
>>>>     
>>>>> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
>>>>> that support transfer of dummy cycles by the hardware directly.
>>>> Hm, not sure this is a good idea. I mean, if we expect regular SPI
>>>> devices to use this feature, then why not, but if it's just for
>>>> spi-mem, I'd recommend implementing a driver-specific exec_op() instead
>>>> of using the default one.
>>> dummy cycles programming is SPI device specific.
>>>
>>> Transfer of dummy bytes by SW or HW controller can be depending on
>>> features supported by controller.
>>>
>>> Adding controller driver specific exec_op() Just for skipping dummy
>>> bytes transfer will have so much of redundant code pretty much what all
>>> spi_mem_exec_op does.
>>>
>>> So in v1, I handled this in controller driver by skipping SW transfer of
>>> dummy bytes during dummy phase and programming dummy cycles in
>>> controller register to allow HW to transfer.
>>>
>>> Based on v1 feedback discussion, added this flag
>>> SPI_MASTER_USES_HW_DUMMY_CYCLES which can be used by controllers
>>> supporting HW dummy bytes transfer and updated spi_mem_exec_op to skip
>>> SW dummy bytes.
>>>
>>> This helps other controllers supporting HW transfer of dummy bytes as
>>> well just to set the flag and use dummy cycles directly.
>> Except saying a spi_message has X dummy cycle is not precise enough.
>> Where are those dummy cycles in the transfer sequence? spi-mem has well
>> defined sequencing (cmd[+addr][+dummy][+data]) so we know exacly where
>> dummy cycles are, but trying to retro-fit the dummy-cycle concept in
>> the generic spi_message is confusing IMHO. If want to avoid code
>> duplication, I'm pretty sure the driver can be reworked so the
>> spi_transfer/exec_op() path can share most of the logic (that probably
>> implies declaring a tegra_qspi_op).
> Something like that might also do the trick:
>
> --->8---
>
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index ef53290b7d24..8b0476f37fbb 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -353,6 +353,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>                  xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
>                  xfers[xferpos].len = op->dummy.nbytes;
>                  xfers[xferpos].tx_nbits = op->dummy.buswidth;
> +               xfers[xferpos].dummy_data = 1;
>                  spi_message_add_tail(&xfers[xferpos], &msg);
>                  xferpos++;
>                  totalxferlen += op->dummy.nbytes;
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 99380c0825db..ecf7989318c5 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -807,6 +807,10 @@ extern void spi_res_release(struct spi_controller *ctlr,
>    *      transfer. If 0 the default (from @spi_device) is used.
>    * @bits_per_word: select a bits_per_word other than the device default
>    *      for this transfer. If 0 the default (from @spi_device) is used.
> + * @dummy_data: set to 1 for a dummy transfer (a transfer whose data is
> + *      ignored). Controllers that are able to issue dummy cycles can ignore
> + *      tx_buf, for those that can't tx_buf will contain dummy bytes. The
> + *      number of  dummy cycles to issue is (len * tx_bits) / 8.
>    * @cs_change: affects chipselect after this transfer completes
>    * @cs_change_delay: delay between cs deassert and assert when
>    *      @cs_change is set and @spi_transfer is not the last in @spi_message
> @@ -919,6 +923,7 @@ struct spi_transfer {
>          struct sg_table tx_sg;
>          struct sg_table rx_sg;
>   
> +       unsigned        dummy_data:1;
>          unsigned        cs_change:1;
>          unsigned        tx_nbits:3;
>          unsigned        rx_nbits:3;

Thanks Boris.

Sorry was thinking of spi flash device only as we only support quad spi 
flash on Tegra QSPI interface.

But to make it more generic where spi message preparation can happen 
from any client driver, agree order of transfers may vary.

Also having controller driver implement exec_op callback is also not 
useful considering cases where spi message transfers dont' go thru spi_mem.

Yes adding dummy_data field to indicate transfer is dummy bytes transfer 
helps for any types of message transfers.

Tegra QSPI controller dummy cycles need be programmed with transfer 
after which dummy cycles are needed.

So, will have v4 to add dummy_data to spi_transfer and will update 
controller driver to convert dummy bytes to dummy cycles and program 
dummy cycles with its previous transfer and skip dummy transfer buffer.

Thanks

Sowjanya

Re: [PATCH v3 5/9] spi: spi-mem: Allow masters to transfer dummy cycles directly by hardware

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1169 bytes --]

On Sat, Dec 12, 2020 at 11:57:15AM +0100, Boris Brezillon wrote:
> Sowjanya Komatineni <skomatineni@nvidia.com> wrote:

> > This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
> > that support transfer of dummy cycles by the hardware directly.

> Hm, not sure this is a good idea. I mean, if we expect regular SPI
> devices to use this feature, then why not, but if it's just for
> spi-mem, I'd recommend implementing a driver-specific exec_op() instead
> of using the default one.

I *have* seen other high speed devices which had padding bits in the
transfer (see regmap's pad_bits feature), I think that corresponds to
flash dummy bits but haven't checked that the hardware support lines up.
I'm not sure it's ever been seen as something that we particularly
needed to speed up with hardware offload though.

> If we go for those core changes, we should at least add a
> ctrl->max_dummy_cycles field so the core can fallback to regular writes
> when the number of dummy cycles in the spi_mem_op exceeds what the
> controller can do.

That seems sensible if there's a risk of controllers being too limited,
which knowing hardware seems likely.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v3 1/9] dt-bindings: clock: tegra: Add clock ID TEGRA210_CLK_QSPI_PM

[Rob Herring]

On Fri, 11 Dec 2020 13:15:55 -0800, Sowjanya Komatineni wrote:
> Tegra210 QSPI clock output has divider DIV2_SEL which will be enabled
> when using DDR interface mode.
> 
> This patch adds clock ID for this to dt-binding.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
>  include/dt-bindings/clock/tegra210-car.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v3 2/9] dt-bindings: spi: Add Tegra Quad SPI device tree binding

[Rob Herring]

On Fri, Dec 11, 2020 at 01:15:56PM -0800, Sowjanya Komatineni wrote:
> This patch adds YAML based device tree binding document for Tegra
> Quad SPI driver.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
>  .../bindings/spi/nvidia,tegra210-quad.yaml         | 130 +++++++++++++++++++++
>  1 file changed, 130 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
> 
> diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
> new file mode 100644
> index 0000000..0b5fea6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
> @@ -0,0 +1,130 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/spi/nvidia,tegra210-quad.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Tegra Quad SPI Controller
> +
> +maintainers:
> +  - Thierry Reding <thierry.reding@gmail.com>
> +  - Jonathan Hunter <jonathanh@nvidia.com>

allOf:
  - $ref: spi-controller.yaml#

> +
> +properties:
> +  compatible:
> +    enum:
> +      - nvidia,tegra210-qspi
> +      - nvidia,tegra186-qspi
> +      - nvidia,tegra194-qspi
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clock-names:
> +    items:
> +      - const: qspi
> +      - const: qspi_out
> +
> +  clocks:
> +    maxItems: 2
> +
> +  resets:
> +    maxItems: 1
> +
> +  dmas:
> +    maxItems: 2
> +
> +  dma-names:
> +    items:
> +      - const: rx
> +      - const: tx
> +
> +patternProperties:
> +  "^.*@[0-9a-f]+":

You can drop '^.*'.

> +    type: object
> +
> +    properties:
> +      compatible:
> +        description:
> +          Compatible of the SPI device.
> +
> +      reg:
> +        maxItems: 1
> +
> +      spi-max-frequency:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description:
> +          Maximum Quad SPI clocking speed of the device in Hz.
> +
> +      spi-rx-bus-width:
> +        description:
> +          Bus width to the Quad SPI bus used for read transfers.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        enum: [1, 2, 4]
> +
> +      spi-tx-bus-width:
> +        description:
> +          Bus width to the Quad SPI bus used for write transfers.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        enum: [1, 2, 4]

All of the above 5 properties are covered by spi-controller.yaml. You 
only need additional constraints here. As 8-bit mode is not supported, 
you need:

spi-tx-bus-width:
  enum: [1, 2, 4]

> +
> +      nvidia,tx-clk-tap-delay:
> +        description:
> +          Delays the clock going out to device with this tap value.
> +          Tap value varies based on platform design trace lengths from Tegra
> +          QSPI to corresponding slave device.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        minimum: 0
> +        maximum: 31
> +
> +      nvidia,rx-clk-tap-delay:
> +        description:
> +          Delays the clock coming in from the device with this tap value.
> +          Tap value varies based on platform design trace lengths from Tegra
> +          QSPI to corresponding slave device.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        minimum: 0
> +        maximum: 255

Please include these properties in your example.

> +
> +    required:
> +      - reg
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clock-names
> +  - clocks
> +  - resets
> +
> +additionalProperties: true

That's generally wrong unless it's a schema to be included by other 
schemas.

unevaluatedProperties: false

> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/tegra210-car.h>
> +    #include <dt-bindings/reset/tegra210-car.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    spi@70410000 {
> +            compatible = "nvidia,tegra210-qspi";
> +            reg = <0x70410000 0x1000>;
> +            interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            clocks = <&tegra_car TEGRA210_CLK_QSPI>,
> +                     <&tegra_car TEGRA210_CLK_QSPI_PM>;
> +            clock-names = "qspi", "qspi_out";
> +            resets = <&tegra_car 211>;
> +            dmas = <&apbdma 5>, <&apbdma 5>;
> +            dma-names = "rx", "tx";
> +
> +            flash@0 {
> +                    compatible = "spi-nor";
> +                    reg = <0>;
> +                    spi-max-frequency = <104000000>;
> +                    spi-tx-bus-width = <2>;
> +                    spi-rx-bus-width = <2>;
> +            };
> +    };
> -- 
> 2.7.4
>