[PATCH] SPI: Add driver for Cadence SPI controller

[Harini Katakam]

Add driver for Cadence SPI controller. This is used in Xilinx Zynq.

Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>
---
 .../devicetree/bindings/spi/spi-cadence.txt        |   25 +
 drivers/spi/Kconfig                                |    7 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-cadence.c                          |  804 ++++++++++++++++++++
 4 files changed, 837 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-cadence.txt
 create mode 100644 drivers/spi/spi-cadence.c

diff --git a/Documentation/devicetree/bindings/spi/spi-cadence.txt b/Documentation/devicetree/bindings/spi/spi-cadence.txt
new file mode 100644
index 0000000..d25bc2d
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-cadence.txt
@@ -0,0 +1,25 @@
+Cadence SPI controller Device Tree Bindings
+-------------------------------------------
+
+Required properties:
+- compatible		: Should be "cdns,spi-r1p6".
+- reg			: Physical base address and size of SPI registers map.
+- interrupts		: Property with a value describing the interrupt
+			  number.
+- interrupt-parent	: Must be core interrupt controller
+- clock-names		: List of input clock names - "ref_clk", "pclk"
+			  (See clock bindings for details).
+- clocks		: Clock phandles (see clock bindings for details).
+- num-chip-select	: Number of chip selects used.
+
+Example:
+
+	spi@e0007000 {
+		clock-names = "ref_clk", "pclk";
+		clocks = <&clkc 26>, <&clkc 35>;
+		compatible = "cdns,spi-r1p6";
+		interrupt-parent = <&intc>;
+		interrupts = <0 49 4>;
+		num-chip-select = /bits/ 16 <4>;
+		reg = <0xe0007000 0x1000>;
+	} ;
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 581ee2a..aeae44a 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -148,6 +148,13 @@ config SPI_BUTTERFLY
 	  inexpensive battery powered microcontroller evaluation board.
 	  This same cable can be used to flash new firmware.
 
+config SPI_CADENCE
+	tristate "Cadence SPI controller"
+	depends on SPI_MASTER
+	help
+	  This selects the Cadence SPI controller master driver
+	  used by Xilinx Zynq.
+
 config SPI_CLPS711X
 	tristate "CLPS711X host SPI controller"
 	depends on ARCH_CLPS711X
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 95af48d..1be2ed7 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_SPI_BFIN_V3)               += spi-bfin-v3.o
 obj-$(CONFIG_SPI_BFIN_SPORT)		+= spi-bfin-sport.o
 obj-$(CONFIG_SPI_BITBANG)		+= spi-bitbang.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi-butterfly.o
+obj-$(CONFIG_SPI_CADENCE)		+= spi-cadence.o
 obj-$(CONFIG_SPI_CLPS711X)		+= spi-clps711x.o
 obj-$(CONFIG_SPI_COLDFIRE_QSPI)		+= spi-coldfire-qspi.o
 obj-$(CONFIG_SPI_DAVINCI)		+= spi-davinci.o
diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
new file mode 100644
index 0000000..7344411
--- /dev/null
+++ b/drivers/spi/spi-cadence.c
@@ -0,0 +1,804 @@
+/*
+ * Cadence SPI controller driver (master mode only)
+ *
+ * Copyright (C) 2008 - 2014 Xilinx, Inc.
+ *
+ * based on Blackfin On-Chip SPI Driver (spi_bfin5xx.c)
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+/* Name of this driver */
+#define CDNS_SPI_NAME		"cdns-spi"
+
+/* Register offset definitions */
+#define CDNS_SPI_CR_OFFSET	0x00 /* Configuration  Register, RW */
+#define CDNS_SPI_ISR_OFFSET	0x04 /* Interrupt Status Register, RO */
+#define CDNS_SPI_IER_OFFSET	0x08 /* Interrupt Enable Register, WO */
+#define CDNS_SPI_IDR_OFFSET	0x0c /* Interrupt Disable Register, WO */
+#define CDNS_SPI_IMR_OFFSET	0x10 /* Interrupt Enabled Mask Register, RO */
+#define CDNS_SPI_ER_OFFSET	0x14 /* Enable/Disable Register, RW */
+#define CDNS_SPI_DR_OFFSET	0x18 /* Delay Register, RW */
+#define CDNS_SPI_TXD_OFFSET	0x1C /* Data Transmit Register, WO */
+#define CDNS_SPI_RXD_OFFSET	0x20 /* Data Receive Register, RO */
+#define CDNS_SPI_SICR_OFFSET	0x24 /* Slave Idle Count Register, RW */
+#define CDNS_SPI_THLD_OFFSET	0x28 /* Transmit FIFO Watermark Register,RW */
+
+/*
+ * SPI Configuration Register bit Masks
+ *
+ * This register contains various control bits that affect the operation
+ * of the SPI controller
+ */
+#define CDNS_SPI_CR_MANSTRT_MASK	0x00010000 /* Manual TX Start */
+#define CDNS_SPI_CR_CPHA_MASK		0x00000004 /* Clock Phase Control */
+#define CDNS_SPI_CR_CPOL_MASK		0x00000002 /* Clock Polarity Control */
+#define CDNS_SPI_CR_SSCTRL_MASK		0x00003C00 /* Slave Select Mask */
+#define CDNS_SPI_CR_BAUD_DIV_MASK	0x00000038 /* Baud Rate Divisor Mask */
+#define CDNS_SPI_CR_MSTREN_MASK		0x00000001 /* Master Enable Mask */
+#define CDNS_SPI_CR_MANSTRTEN_MASK	0x00008000 /* Manual TX Enable Mask */
+#define CDNS_SPI_CR_SSFORCE_MASK	0x00004000 /* Manual SS Enable Mask */
+#define CDNS_SPI_CR_BAUD_DIV_4_MASK	0x00000008 /* Default Baud Div Mask */
+#define CDNS_SPI_CR_DEFAULT_MASK	(CDNS_SPI_CR_MSTREN_MASK | \
+					CDNS_SPI_CR_SSCTRL_MASK | \
+					CDNS_SPI_CR_SSFORCE_MASK | \
+					CDNS_SPI_CR_BAUD_DIV_4_MASK)
+
+/*
+ * SPI Configuration Register - Baud rate and slave select
+ *
+ * These are the values used in the calculation of baud rate divisor and
+ * setting the slave select.
+ */
+
+#define CDNS_SPI_BAUD_DIV_MAX		7 /* Baud rate divisor maximum */
+#define CDNS_SPI_BAUD_DIV_MIN		1 /* Baud rate divisor minimum */
+#define CDNS_SPI_BAUD_DIV_SHIFT		3 /* Baud rate divisor shift in CR */
+#define CDNS_SPI_SS_SHIFT		10 /* Slave Select field shift in CR */
+#define CDNS_SPI_SS0			0x1 /* Slave Select zero */
+
+/*
+ * SPI Interrupt Registers bit Masks
+ *
+ * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
+ * bit definitions.
+ */
+#define CDNS_SPI_IXR_TXOW_MASK	0x00000004 /* SPI TX FIFO Overwater */
+#define CDNS_SPI_IXR_MODF_MASK	0x00000002 /* SPI Mode Fault */
+#define CDNS_SPI_IXR_RXNEMTY_MASK 0x00000010 /* SPI RX FIFO Not Empty */
+#define CDNS_SPI_IXR_DEFAULT_MASK	(CDNS_SPI_IXR_TXOW_MASK | \
+					CDNS_SPI_IXR_MODF_MASK)
+#define CDNS_SPI_IXR_TXFULL_MASK	0x00000008 /* SPI TX Full */
+#define CDNS_SPI_IXR_ALL_MASK	0x0000007F /* SPI all interrupts */
+
+/*
+ * SPI Enable Register bit Masks
+ *
+ * This register is used to enable or disable the SPI controller
+ */
+#define CDNS_SPI_ER_ENABLE_MASK	0x00000001 /* SPI Enable Bit Mask */
+#define CDNS_SPI_ER_DISABLE_MASK	0x0 /* SPI Disable Bit Mask */
+
+/* SPI timeout value */
+#define CDNS_SPI_TIMEOUT	(5 * HZ)
+
+/* SPI FIFO depth in bytes */
+#define CDNS_SPI_FIFO_DEPTH	128
+
+/* Macros for the SPI controller read/write */
+#define cdns_spi_read(addr)	readl_relaxed(addr)
+#define cdns_spi_write(addr, val)	writel_relaxed((val), (addr))
+
+/* Driver state - suspend/ready */
+enum driver_state_val {
+	CDNS_SPI_DRIVER_STATE_READY = 0,
+	CDNS_SPI_DRIVER_STATE_SUSPEND
+};
+
+/**
+ * struct cdns_spi - This definition defines spi driver instance
+ * @regs:		Virtual address of the SPI controller registers
+ * @ref_clk:		Pointer to the peripheral clock
+ * @pclk:		Pointer to the APB clock
+ * @speed_hz:		Current SPI bus clock speed in Hz
+ * @txbuf:		Pointer	to the TX buffer
+ * @rxbuf:		Pointer to the RX buffer
+ * @remaining_bytes:	Number of bytes left to transfer
+ * @requested_bytes:	Number of bytes requested
+ * @dev_busy:		Device busy flag
+ * @done:		Transfer complete status
+ * @driver_state:	Describes driver state - ready/suspended
+ */
+struct cdns_spi {
+	void __iomem *regs;
+	struct clk *ref_clk;
+	struct clk *pclk;
+	u32 speed_hz;
+	const u8 *txbuf;
+	u8 *rxbuf;
+	int remaining_bytes;
+	int requested_bytes;
+	u8 dev_busy;
+	struct completion done;
+	enum driver_state_val driver_state;
+};
+
+/**
+ * cdns_spi_init_hw - Initialize the hardware and configure the SPI controller
+ * @regs_base:		Base address of SPI controller
+ *
+ * On reset the SPI controller is configured to be in master mode, baud rate
+ * divisor is set to 4, threshold value for TX FIFO not full interrupt is set
+ * to 1 and size of the word to be transferred as 8 bit.
+ * This function initializes the SPI controller to disable and clear all the
+ * interrupts, enable manual slave select and manual start, deselect all the
+ * chip select lines, and enable the SPI controller.
+ */
+static void cdns_spi_init_hw(void __iomem *regs_base)
+{
+	cdns_spi_write(regs_base + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+	cdns_spi_write(regs_base + CDNS_SPI_IDR_OFFSET, CDNS_SPI_IXR_ALL_MASK);
+
+	/* Clear the RX FIFO */
+	while (cdns_spi_read(regs_base + CDNS_SPI_ISR_OFFSET) &
+	       CDNS_SPI_IXR_RXNEMTY_MASK)
+		cdns_spi_read(regs_base + CDNS_SPI_RXD_OFFSET);
+
+	cdns_spi_write(regs_base + CDNS_SPI_ISR_OFFSET, CDNS_SPI_IXR_ALL_MASK);
+	cdns_spi_write(regs_base + CDNS_SPI_CR_OFFSET,
+		       CDNS_SPI_CR_DEFAULT_MASK);
+	cdns_spi_write(regs_base + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_ENABLE_MASK);
+}
+
+/**
+ * cdns_spi_chipselect - Select or deselect the chip select line
+ * @spi:	Pointer to the spi_device structure
+ * @is_on:	Select(1) or deselect (0) the chip select line
+ */
+static void cdns_spi_chipselect(struct spi_device *spi, int is_on)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
+	u32 ctrl_reg;
+
+	ctrl_reg = cdns_spi_read(xspi->regs + CDNS_SPI_CR_OFFSET);
+
+	if (is_on) {
+		/* Select the slave */
+		ctrl_reg &= ~CDNS_SPI_CR_SSCTRL_MASK;
+		ctrl_reg |= ((~(CDNS_SPI_SS0 << spi->chip_select)) <<
+			     CDNS_SPI_SS_SHIFT) & CDNS_SPI_CR_SSCTRL_MASK;
+	} else {
+		/* Deselect the slave */
+		ctrl_reg |= CDNS_SPI_CR_SSCTRL_MASK;
+	}
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_CR_OFFSET, ctrl_reg);
+}
+
+/**
+ * cdns_spi_config_clock - Sets clock polarity, phase and frequency
+ * @spi:	Pointer to the spi_device structure
+ * @transfer:	Pointer to the spi_transfer structure which provides
+ *		information about next transfer setup parameters
+ *
+ * Sets the requested clock polarity, phase and frequency.
+ * Note: If the requested frequency is not an exact match with what can be
+ * obtained using the prescalar value the driver sets the clock frequency which
+ * is lower than the requested frequency (maximum lower) for the transfer. If
+ * the requested frequency is higher or lower than that is supported by the SPI
+ * controller the driver will set the highest or lowest frequency supported by
+ * controller.
+ */
+static void cdns_spi_config_clock(struct spi_device *spi,
+		struct spi_transfer *transfer)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
+	u32 ctrl_reg, req_hz, baud_rate_val;
+	unsigned long frequency;
+
+	if (transfer && transfer->speed_hz)
+		req_hz = transfer->speed_hz;
+	else
+		req_hz = spi->max_speed_hz;
+
+	frequency = clk_get_rate(xspi->ref_clk);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+	ctrl_reg = cdns_spi_read(xspi->regs + CDNS_SPI_CR_OFFSET);
+
+	/* Set the SPI clock phase and clock polarity */
+	ctrl_reg &= ~(CDNS_SPI_CR_CPHA_MASK | CDNS_SPI_CR_CPOL_MASK);
+	if (spi->mode & SPI_CPHA)
+		ctrl_reg |= CDNS_SPI_CR_CPHA_MASK;
+	if (spi->mode & SPI_CPOL)
+		ctrl_reg |= CDNS_SPI_CR_CPOL_MASK;
+
+	/* Set the clock frequency */
+	if (xspi->speed_hz != req_hz) {
+		/* first valid value is 1 */
+		baud_rate_val = CDNS_SPI_BAUD_DIV_MIN;
+		while ((baud_rate_val < CDNS_SPI_BAUD_DIV_MAX) &&
+		       (frequency / (2 << baud_rate_val)) > req_hz)
+			baud_rate_val++;
+
+		ctrl_reg &= ~CDNS_SPI_CR_BAUD_DIV_MASK;
+		ctrl_reg |= baud_rate_val << CDNS_SPI_BAUD_DIV_SHIFT;
+
+		xspi->speed_hz = frequency / (2 << baud_rate_val);
+	}
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_CR_OFFSET, ctrl_reg);
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_ENABLE_MASK);
+}
+
+/**
+ * cdns_spi_setup_transfer - Configure SPI controller for specified transfer
+ * @spi:	Pointer to the spi_device structure
+ * @transfer:	Pointer to the spi_transfer structure which provides
+ *		information about next transfer setup parameters
+ *
+ * Sets the operational mode of SPI controller for the next SPI transfer and
+ * sets the requested clock frequency.
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cdns_spi_setup_transfer(struct spi_device *spi,
+		struct spi_transfer *transfer)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
+	u8 bits_per_word;
+
+	bits_per_word = transfer ?
+			transfer->bits_per_word : spi->bits_per_word;
+
+	if (bits_per_word != 8) {
+		dev_err(&spi->dev, "%s, unsupported bits per word %x\n",
+			__func__, spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	cdns_spi_config_clock(spi, transfer);
+
+	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u clock speed\n",
+		__func__, spi->mode, spi->bits_per_word,
+		xspi->speed_hz);
+
+	return 0;
+}
+
+/**
+ * cdns_spi_setup - Configure the SPI controller
+ * @spi:	Pointer to the spi_device structure
+ *
+ * Sets the operational mode of SPI controller for the next SPI transfer, sets
+ * the baud rate and divisor value to setup the requested spi clock.
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cdns_spi_setup(struct spi_device *spi)
+{
+	if (!spi->max_speed_hz)
+		return -EINVAL;
+
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	return cdns_spi_setup_transfer(spi, NULL);
+}
+
+/**
+ * cdns_spi_fill_tx_fifo - Fills the TX FIFO with as many bytes as possible
+ * @xspi:	Pointer to the cdns_spi structure
+ */
+static void cdns_spi_fill_tx_fifo(struct cdns_spi *xspi)
+{
+	unsigned long trans_cnt = 0;
+
+	while ((trans_cnt < CDNS_SPI_FIFO_DEPTH) &&
+	       (xspi->remaining_bytes > 0)) {
+		if (xspi->txbuf)
+			cdns_spi_write(xspi->regs + CDNS_SPI_TXD_OFFSET,
+				       *xspi->txbuf++);
+		else
+			cdns_spi_write(xspi->regs + CDNS_SPI_TXD_OFFSET, 0);
+
+		xspi->remaining_bytes--;
+		trans_cnt++;
+	}
+}
+
+/**
+ * cdns_spi_irq - Interrupt service routine of the SPI controller
+ * @irq:	IRQ number
+ * @dev_id:	Pointer to the xspi structure
+ *
+ * This function handles TX empty and Mode Fault interrupts only.
+ * On TX empty interrupt this function reads the received data from RX FIFO and
+ * fills the TX FIFO if there is any data remaining to be transferred.
+ * On Mode Fault interrupt this function indicates that transfer is completed,
+ * the SPI subsystem will identify the error as the remaining bytes to be
+ * transferred is non-zero.
+ *
+ * Return:	IRQ_HANDLED always
+ */
+static irqreturn_t cdns_spi_irq(int irq, void *dev_id)
+{
+	struct cdns_spi *xspi = dev_id;
+	u32 intr_status;
+
+	intr_status = cdns_spi_read(xspi->regs + CDNS_SPI_ISR_OFFSET);
+	cdns_spi_write(xspi->regs + CDNS_SPI_ISR_OFFSET, intr_status);
+
+	if (intr_status & CDNS_SPI_IXR_MODF_MASK) {
+		/* Indicate that transfer is completed, the SPI subsystem will
+		 * identify the error as the remaining bytes to be
+		 * transferred is non-zero
+		 */
+		cdns_spi_write(xspi->regs + CDNS_SPI_IDR_OFFSET,
+			       CDNS_SPI_IXR_DEFAULT_MASK);
+		complete(&xspi->done);
+	} else if (intr_status & CDNS_SPI_IXR_TXOW_MASK) {
+		unsigned long trans_cnt;
+
+		trans_cnt = xspi->requested_bytes - xspi->remaining_bytes;
+
+		/* Read out the data from the RX FIFO */
+		while (trans_cnt) {
+			u8 data;
+
+			data = cdns_spi_read(xspi->regs + CDNS_SPI_RXD_OFFSET);
+			if (xspi->rxbuf)
+				*xspi->rxbuf++ = data;
+
+			xspi->requested_bytes--;
+			trans_cnt--;
+		}
+
+		if (xspi->remaining_bytes) {
+			/* There is more data to send */
+			cdns_spi_fill_tx_fifo(xspi);
+		} else {
+			/* Transfer is completed */
+			cdns_spi_write(xspi->regs + CDNS_SPI_IDR_OFFSET,
+				       CDNS_SPI_IXR_DEFAULT_MASK);
+			complete(&xspi->done);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * cdns_spi_reset_controller - Resets SPI controller
+ * @spi:	Pointer to the spi_device structure
+ *
+ * This function disables the interrupts, de-asserts the chip select and
+ * disables the SPI controller.
+ */
+static void cdns_spi_reset_controller(struct spi_device *spi)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_IDR_OFFSET,
+		       CDNS_SPI_IXR_DEFAULT_MASK);
+	cdns_spi_chipselect(spi, 0);
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+}
+
+/**
+ * cdns_spi_start_transfer - Initiates the SPI transfer
+ * @spi:	Pointer to the spi_device structure
+ * @transfer:	Pointer to the spi_transfer structure which provides
+ *		information about next transfer parameters
+ *
+ * This function fills the TX FIFO, starts the SPI transfer, and waits for the
+ * transfer to be completed.
+ *
+ * Return:	Number of bytes transferred in the last transfer
+ */
+static int cdns_spi_start_transfer(struct spi_device *spi,
+			struct spi_transfer *transfer)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(spi->master);
+	int ret;
+
+	xspi->txbuf = transfer->tx_buf;
+	xspi->rxbuf = transfer->rx_buf;
+	xspi->remaining_bytes = transfer->len;
+	xspi->requested_bytes = transfer->len;
+	reinit_completion(&xspi->done);
+
+	cdns_spi_fill_tx_fifo(xspi);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_IER_OFFSET,
+		       CDNS_SPI_IXR_DEFAULT_MASK);
+
+	ret = wait_for_completion_interruptible_timeout(&xspi->done,
+							CDNS_SPI_TIMEOUT);
+	if (ret < 1) {
+		cdns_spi_reset_controller(spi);
+		if (!ret)
+			return -ETIMEDOUT;
+
+		return ret;
+	}
+
+	return transfer->len - xspi->remaining_bytes;
+}
+
+/**
+ * cdns_prepare_transfer_hardware - Prepares hardware for transfer.
+ * @master:	Pointer to the spi_master structure which provides
+ *		information about the controller.
+ *
+ * This function enables SPI master controller.
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cdns_prepare_transfer_hardware(struct spi_master *master)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+
+	if (xspi->driver_state != CDNS_SPI_DRIVER_STATE_READY)
+		return -EINVAL;
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_ENABLE_MASK);
+
+	return 0;
+}
+
+/**
+ * cdns_transfer_one_message - Sets up and transfer a message.
+ * @master:	Pointer to the spi_master structure which provides
+ *		information about the controller.
+ * @msg:	Pointer to the spi_message which contains the
+ *		data to be transferred.
+ *
+ * This function calls the necessary functions to setup operational mode,
+ * clock, control chip select and completes the transfer.
+ *
+ * Return:	0 on success and error value on error.
+ */
+static int cdns_transfer_one_message(struct spi_master *master,
+				     struct spi_message *msg)
+{
+	struct spi_device *spi;
+	unsigned cs_change = 1;
+	int status = 0, length = 0;
+	struct spi_transfer *transfer;
+
+	spi = msg->spi;
+
+	list_for_each_entry(transfer, &msg->transfers, transfer_list) {
+		if ((transfer->bits_per_word || transfer->speed_hz) &&
+		    cs_change) {
+			status = cdns_spi_setup_transfer(spi, transfer);
+			if (status < 0)
+				break;
+		}
+
+		if (cs_change)
+			cdns_spi_chipselect(spi, 1);
+
+		cs_change = transfer->cs_change;
+
+		if (!transfer->tx_buf && !transfer->rx_buf &&
+			transfer->len) {
+			status = -EINVAL;
+			break;
+		}
+
+		if (transfer->len)
+			length = cdns_spi_start_transfer(spi, transfer);
+
+		if (length != transfer->len) {
+			if (length > 0)
+				status = -EMSGSIZE;
+			else
+				status = length;
+			break;
+		}
+		msg->actual_length += length;
+		status = 0;
+
+		if (transfer->delay_usecs)
+			udelay(transfer->delay_usecs);
+
+		if (!cs_change)
+			continue;
+
+		if (transfer->transfer_list.next == &msg->transfers)
+			break;
+
+		cdns_spi_chipselect(spi, 0);
+	}
+
+	if (status || !cs_change)
+		cdns_spi_chipselect(spi, 0);
+
+	msg->status = status;
+	spi_finalize_current_message(master);
+
+	return status;
+}
+
+/**
+ * cdns_unprepare_transfer_hardware - Relaxes hardware after transfer
+ * @master:	Pointer to the spi_master structure which provides
+ *		information about the controller.
+ *
+ * This function disables the SPI master controller.
+ *
+ * Return:	0 always
+ */
+static int cdns_unprepare_transfer_hardware(struct spi_master *master)
+{
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+
+	return 0;
+}
+
+/**
+ * cdns_spi_probe - Probe method for the SPI driver
+ * @pdev:	Pointer to the platform_device structure
+ *
+ * This function initializes the driver data structures and the hardware.
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cdns_spi_probe(struct platform_device *pdev)
+{
+	int ret = 0, irq;
+	struct spi_master *master;
+	struct cdns_spi *xspi;
+	struct resource *res;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*xspi));
+	if (master == NULL)
+		return -ENOMEM;
+
+	xspi = spi_master_get_devdata(master);
+	master->dev.of_node = pdev->dev.of_node;
+	platform_set_drvdata(pdev, master);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	xspi->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(xspi->regs)) {
+		ret = PTR_ERR(xspi->regs);
+		goto remove_master;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		ret = -ENXIO;
+		dev_err(&pdev->dev, "irq number is negative\n");
+		goto remove_master;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, cdns_spi_irq,
+			       0, pdev->name, xspi);
+	if (ret != 0) {
+		ret = -ENXIO;
+		dev_err(&pdev->dev, "request_irq failed\n");
+		goto remove_master;
+	}
+
+	xspi->pclk = devm_clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(xspi->pclk)) {
+		dev_err(&pdev->dev, "pclk clock not found.\n");
+		ret = PTR_ERR(xspi->pclk);
+		goto remove_master;
+	}
+
+	xspi->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
+	if (IS_ERR(xspi->ref_clk)) {
+		dev_err(&pdev->dev, "ref_clk clock not found.\n");
+		ret = PTR_ERR(xspi->ref_clk);
+		goto remove_master;
+	}
+
+	ret = clk_prepare_enable(xspi->pclk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable APB clock.\n");
+		goto remove_master;
+	}
+
+	ret = clk_prepare_enable(xspi->ref_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable device clock.\n");
+		goto clk_dis_apb;
+	}
+
+	/* SPI controller initializations */
+	cdns_spi_init_hw(xspi->regs);
+
+	init_completion(&xspi->done);
+
+	ret = of_property_read_u16(pdev->dev.of_node, "num-chip-select",
+				   &master->num_chipselect);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "couldn't determine num-chip-select\n");
+		goto clk_dis_all;
+	}
+	master->setup = cdns_spi_setup;
+	master->prepare_transfer_hardware = cdns_prepare_transfer_hardware;
+	master->transfer_one_message = cdns_transfer_one_message;
+	master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;
+	master->mode_bits = SPI_CPOL | SPI_CPHA;
+
+	/* Set to default valid value */
+	xspi->speed_hz = clk_get_rate(xspi->ref_clk) / 4;
+
+	xspi->driver_state = CDNS_SPI_DRIVER_STATE_READY;
+
+	ret = spi_register_master(master);
+	if (ret) {
+		dev_err(&pdev->dev, "spi_register_master failed\n");
+		goto clk_dis_all;
+	}
+
+	dev_info(&pdev->dev, "at 0x%08X mapped to 0x%08X, irq=%d\n",
+		 res->start, (u32 __force)xspi->regs, irq);
+
+	return ret;
+
+clk_dis_all:
+	clk_disable_unprepare(xspi->ref_clk);
+clk_dis_apb:
+	clk_disable_unprepare(xspi->pclk);
+remove_master:
+	spi_master_put(master);
+	return ret;
+}
+
+/**
+ * cdns_spi_remove - Remove method for the SPI driver
+ * @pdev:	Pointer to the platform_device structure
+ *
+ * This function is called if a device is physically removed from the system or
+ * if the driver module is being unloaded. It frees all resources allocated to
+ * the device.
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cdns_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+
+	clk_disable_unprepare(xspi->ref_clk);
+	clk_disable_unprepare(xspi->pclk);
+
+	spi_unregister_master(master);
+	spi_master_put(master);
+
+	dev_dbg(&pdev->dev, "remove succeeded\n");
+	return 0;
+}
+
+/**
+ * cdns_spi_suspend - Suspend method for the SPI driver
+ * @dev:	Address of the platform_device structure
+ *
+ * This function disables the SPI controller and
+ * changes the driver state to "suspend"
+ *
+ * Return:	0 on success and error value on error
+ */
+static int __maybe_unused cdns_spi_suspend(struct device *dev)
+{
+	struct platform_device *pdev = container_of(dev,
+			struct platform_device, dev);
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+	u32 ctrl_reg;
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_IDR_OFFSET,
+		       CDNS_SPI_IXR_DEFAULT_MASK);
+	complete(&xspi->done);
+
+	ctrl_reg = cdns_spi_read(xspi->regs + CDNS_SPI_CR_OFFSET);
+	ctrl_reg |= CDNS_SPI_CR_SSCTRL_MASK;
+	cdns_spi_write(xspi->regs + CDNS_SPI_CR_OFFSET, ctrl_reg);
+
+	cdns_spi_write(xspi->regs + CDNS_SPI_ER_OFFSET,
+		       CDNS_SPI_ER_DISABLE_MASK);
+
+	xspi->driver_state = CDNS_SPI_DRIVER_STATE_SUSPEND;
+
+	clk_disable(xspi->ref_clk);
+	clk_disable(xspi->pclk);
+
+	dev_dbg(&pdev->dev, "suspend succeeded\n");
+	return 0;
+}
+
+/**
+ * cdns_spi_resume - Resume method for the SPI driver
+ * @dev:	Address of the platform_device structure
+ *
+ * This function changes the driver state to "ready"
+ *
+ * Return:	0 on success and error value on error
+ */
+static int __maybe_unused cdns_spi_resume(struct device *dev)
+{
+	struct platform_device *pdev = container_of(dev,
+			struct platform_device, dev);
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+	int ret = 0;
+
+	ret = clk_enable(xspi->pclk);
+	if (ret) {
+		dev_err(dev, "Cannot enable APB clock.\n");
+		return ret;
+	}
+
+	ret = clk_enable(xspi->ref_clk);
+	if (ret) {
+		dev_err(dev, "Cannot enable device clock.\n");
+		clk_disable(xspi->pclk);
+		return ret;
+	}
+
+	xspi->driver_state = CDNS_SPI_DRIVER_STATE_READY;
+
+	dev_dbg(&pdev->dev, "resume succeeded\n");
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(cdns_spi_dev_pm_ops, cdns_spi_suspend,
+			 cdns_spi_resume);
+
+/* Work with hotplug and coldplug */
+MODULE_ALIAS("platform:" CDNS_SPI_NAME);
+
+static struct of_device_id cdns_spi_of_match[] = {
+	{ .compatible = "cdns,spi-r1p6" },
+	{ /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, cdns_spi_of_match);
+
+/* cdns_spi_driver - This structure defines the SPI subsystem platform driver */
+static struct platform_driver cdns_spi_driver = {
+	.probe	= cdns_spi_probe,
+	.remove	= cdns_spi_remove,
+	.driver = {
+		.name = CDNS_SPI_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = cdns_spi_of_match,
+		.pm = &cdns_spi_dev_pm_ops,
+	},
+};
+
+module_platform_driver(cdns_spi_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Cadence SPI driver");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5

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