drivers/spi/spi-xilinx.c - kernel/bruno - Git at Google

 /*
  * Xilinx SPI controller driver (master mode only)
  *
  * Author: MontaVista Software, Inc.
  *	source@mvista.com
  *
  * Copyright (c) 2010 Secret Lab Technologies, Ltd.
  * Copyright (c) 2009 Intel Corporation
  * 2002-2007 (c) MontaVista Software, Inc.

  * 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.
  */

 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/spi/xilinx_spi.h>
 #include <linux/io.h>

 #define XILINX_SPI_NAME "xilinx_spi"

 /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
  * Product Specification", DS464
  */
 #define XSPI_CR_OFFSET		0x60	/* Control Register */

 #define XSPI_CR_LOOP		0x01
 #define XSPI_CR_ENABLE		0x02
 #define XSPI_CR_MASTER_MODE	0x04
 #define XSPI_CR_CPOL		0x08
 #define XSPI_CR_CPHA		0x10
 #define XSPI_CR_MODE_MASK	(XSPI_CR_CPHA | XSPI_CR_CPOL)
 #define XSPI_CR_TXFIFO_RESET	0x20
 #define XSPI_CR_RXFIFO_RESET	0x40
 #define XSPI_CR_MANUAL_SSELECT	0x80
 #define XSPI_CR_TRANS_INHIBIT	0x100
 #define XSPI_CR_LSB_FIRST	0x200

 #define XSPI_SR_OFFSET		0x64	/* Status Register */

 #define XSPI_SR_RX_EMPTY_MASK	0x01	/* Receive FIFO is empty */
 #define XSPI_SR_RX_FULL_MASK	0x02	/* Receive FIFO is full */
 #define XSPI_SR_TX_EMPTY_MASK	0x04	/* Transmit FIFO is empty */
 #define XSPI_SR_TX_FULL_MASK	0x08	/* Transmit FIFO is full */
 #define XSPI_SR_MODE_FAULT_MASK	0x10	/* Mode fault error */

 #define XSPI_TXD_OFFSET		0x68	/* Data Transmit Register */
 #define XSPI_RXD_OFFSET		0x6c	/* Data Receive Register */

 #define XSPI_SSR_OFFSET		0x70	/* 32-bit Slave Select Register */

 /* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
  * IPIF registers are 32 bit
  */
 #define XIPIF_V123B_DGIER_OFFSET	0x1c	/* IPIF global int enable reg */
 #define XIPIF_V123B_GINTR_ENABLE	0x80000000

 #define XIPIF_V123B_IISR_OFFSET		0x20	/* IPIF interrupt status reg */
 #define XIPIF_V123B_IIER_OFFSET		0x28	/* IPIF interrupt enable reg */

 #define XSPI_INTR_MODE_FAULT		0x01	/* Mode fault error */
 #define XSPI_INTR_SLAVE_MODE_FAULT	0x02	/* Selected as slave while
 						 * disabled */
 #define XSPI_INTR_TX_EMPTY		0x04	/* TxFIFO is empty */
 #define XSPI_INTR_TX_UNDERRUN		0x08	/* TxFIFO was underrun */
 #define XSPI_INTR_RX_FULL		0x10	/* RxFIFO is full */
 #define XSPI_INTR_RX_OVERRUN		0x20	/* RxFIFO was overrun */
 #define XSPI_INTR_TX_HALF_EMPTY		0x40	/* TxFIFO is half empty */

 #define XIPIF_V123B_RESETR_OFFSET	0x40	/* IPIF reset register */
 #define XIPIF_V123B_RESET_MASK		0x0a	/* the value to write */

 struct xilinx_spi {
 	/* bitbang has to be first */
 	struct spi_bitbang bitbang;
 	struct completion done;
 	void __iomem	*regs;	/* virt. address of the control registers */

 	int		irq;

 	u8 *rx_ptr;		/* pointer in the Tx buffer */
 	const u8 *tx_ptr;	/* pointer in the Rx buffer */
 	int remaining_bytes;	/* the number of bytes left to transfer */
 	u8 bits_per_word;
 	unsigned int (*read_fn)(void __iomem *);
 	void (*write_fn)(u32, void __iomem *);
 	void (*tx_fn)(struct xilinx_spi *);
 	void (*rx_fn)(struct xilinx_spi *);
 };

 static void xspi_write32(u32 val, void __iomem *addr)
 {
 	iowrite32(val, addr);
 }

 static unsigned int xspi_read32(void __iomem *addr)
 {
 	return ioread32(addr);
 }

 static void xspi_write32_be(u32 val, void __iomem *addr)
 {
 	iowrite32be(val, addr);
 }

 static unsigned int xspi_read32_be(void __iomem *addr)
 {
 	return ioread32be(addr);
 }

 static void xspi_tx8(struct xilinx_spi *xspi)
 {
 	xspi->write_fn(*xspi->tx_ptr, xspi->regs + XSPI_TXD_OFFSET);
 	xspi->tx_ptr++;
 }

 static void xspi_tx16(struct xilinx_spi *xspi)
 {
 	xspi->write_fn(*(u16 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
 	xspi->tx_ptr += 2;
 }

 static void xspi_tx32(struct xilinx_spi *xspi)
 {
 	xspi->write_fn(*(u32 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
 	xspi->tx_ptr += 4;
 }

 static void xspi_rx8(struct xilinx_spi *xspi)
 {
 	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 	if (xspi->rx_ptr) {
 		*xspi->rx_ptr = data & 0xff;
 		xspi->rx_ptr++;
 	}
 }

 static void xspi_rx16(struct xilinx_spi *xspi)
 {
 	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 	if (xspi->rx_ptr) {
 		*(u16 *)(xspi->rx_ptr) = data & 0xffff;
 		xspi->rx_ptr += 2;
 	}
 }

 static void xspi_rx32(struct xilinx_spi *xspi)
 {
 	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
 	if (xspi->rx_ptr) {
 		*(u32 *)(xspi->rx_ptr) = data;
 		xspi->rx_ptr += 4;
 	}
 }

 static void xspi_init_hw(struct xilinx_spi *xspi)
 {
 	void __iomem *regs_base = xspi->regs;

 	/* Reset the SPI device */
 	xspi->write_fn(XIPIF_V123B_RESET_MASK,
 		regs_base + XIPIF_V123B_RESETR_OFFSET);
 	/* Disable all the interrupts just in case */
 	xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
 	/* Enable the global IPIF interrupt */
 	xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
 		regs_base + XIPIF_V123B_DGIER_OFFSET);
 	/* Deselect the slave on the SPI bus */
 	xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
 	/* Disable the transmitter, enable Manual Slave Select Assertion,
 	 * put SPI controller into master mode, and enable it */
 	xspi->write_fn(XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT |
 		XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET |
 		XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET);
 }

 static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
 {
 	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);

 	if (is_on == BITBANG_CS_INACTIVE) {
 		/* Deselect the slave on the SPI bus */
 		xspi->write_fn(0xffff, xspi->regs + XSPI_SSR_OFFSET);
 	} else if (is_on == BITBANG_CS_ACTIVE) {
 		/* Set the SPI clock phase and polarity */
 		u16 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET)
 			 & ~XSPI_CR_MODE_MASK;
 		if (spi->mode & SPI_CPHA)
 			cr |= XSPI_CR_CPHA;
 		if (spi->mode & SPI_CPOL)
 			cr |= XSPI_CR_CPOL;
 		xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);

 		/* We do not check spi->max_speed_hz here as the SPI clock
 		 * frequency is not software programmable (the IP block design
 		 * parameter)
 		 */

 		/* Activate the chip select */
 		xspi->write_fn(~(0x0001 << spi->chip_select),
 			xspi->regs + XSPI_SSR_OFFSET);
 	}
 }

 /* spi_bitbang requires custom setup_transfer() to be defined if there is a
  * custom txrx_bufs().
  */
 static int xilinx_spi_setup_transfer(struct spi_device *spi,
 		struct spi_transfer *t)
 {
 	return 0;
 }

 static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi)
 {
 	u8 sr;

 	/* Fill the Tx FIFO with as many bytes as possible */
 	sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 	while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) {
 		if (xspi->tx_ptr)
 			xspi->tx_fn(xspi);
 		else
 			xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
 		xspi->remaining_bytes -= xspi->bits_per_word / 8;
 		sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 	}
 }

 static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
 {
 	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
 	u32 ipif_ier;

 	/* We get here with transmitter inhibited */

 	xspi->tx_ptr = t->tx_buf;
 	xspi->rx_ptr = t->rx_buf;
 	xspi->remaining_bytes = t->len;
 	reinit_completion(&xspi->done);


 	/* Enable the transmit empty interrupt, which we use to determine
 	 * progress on the transmission.
 	 */
 	ipif_ier = xspi->read_fn(xspi->regs + XIPIF_V123B_IIER_OFFSET);
 	xspi->write_fn(ipif_ier | XSPI_INTR_TX_EMPTY,
 		xspi->regs + XIPIF_V123B_IIER_OFFSET);

 	for (;;) {
 		u16 cr;
 		u8 sr;

 		xilinx_spi_fill_tx_fifo(xspi);

 		/* Start the transfer by not inhibiting the transmitter any
 		 * longer
 		 */
 		cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
 							~XSPI_CR_TRANS_INHIBIT;
 		xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);

 		wait_for_completion(&xspi->done);

 		/* A transmit has just completed. Process received data and
 		 * check for more data to transmit. Always inhibit the
 		 * transmitter while the Isr refills the transmit register/FIFO,
 		 * or make sure it is stopped if we're done.
 		 */
 		cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 		xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
 			       xspi->regs + XSPI_CR_OFFSET);

 		/* Read out all the data from the Rx FIFO */
 		sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 		while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
 			xspi->rx_fn(xspi);
 			sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
 		}

 		/* See if there is more data to send */
 		if (xspi->remaining_bytes <= 0)
 			break;
 	}

 	/* Disable the transmit empty interrupt */
 	xspi->write_fn(ipif_ier, xspi->regs + XIPIF_V123B_IIER_OFFSET);

 	return t->len - xspi->remaining_bytes;
 }


 /* This driver supports single master mode only. Hence Tx FIFO Empty
  * is the only interrupt we care about.
  * Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
  * Fault are not to happen.
  */
 static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
 {
 	struct xilinx_spi *xspi = dev_id;
 	u32 ipif_isr;

 	/* Get the IPIF interrupts, and clear them immediately */
 	ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
 	xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);

 	if (ipif_isr & XSPI_INTR_TX_EMPTY) {	/* Transmission completed */
 		complete(&xspi->done);
 	}

 	return IRQ_HANDLED;
 }

 static const struct of_device_id xilinx_spi_of_match[] = {
 	{ .compatible = "xlnx,xps-spi-2.00.a", },
 	{ .compatible = "xlnx,xps-spi-2.00.b", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);

 static int xilinx_spi_probe(struct platform_device *pdev)
 {
 	struct xilinx_spi *xspi;
 	struct xspi_platform_data *pdata;
 	struct resource *res;
 	int ret, num_cs = 0, bits_per_word = 8;
 	struct spi_master *master;
 	u32 tmp;
 	u8 i;

 	pdata = dev_get_platdata(&pdev->dev);
 	if (pdata) {
 		num_cs = pdata->num_chipselect;
 		bits_per_word = pdata->bits_per_word;
 	} else {
 		of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits",
 					  &num_cs);
 	}

 	if (!num_cs) {
 		dev_err(&pdev->dev,
 			"Missing slave select configuration data\n");
 		return -EINVAL;
 	}

 	master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi));
 	if (!master)
 		return -ENODEV;

 	/* the spi->mode bits understood by this driver: */
 	master->mode_bits = SPI_CPOL | SPI_CPHA;

 	xspi = spi_master_get_devdata(master);
 	xspi->bitbang.master = master;
 	xspi->bitbang.chipselect = xilinx_spi_chipselect;
 	xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
 	xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
 	init_completion(&xspi->done);

 	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 put_master;
 	}

 	master->bus_num = pdev->id;
 	master->num_chipselect = num_cs;
 	master->dev.of_node = pdev->dev.of_node;

 	/*
 	 * Detect endianess on the IP via loop bit in CR. Detection
 	 * must be done before reset is sent because incorrect reset
 	 * value generates error interrupt.
 	 * Setup little endian helper functions first and try to use them
 	 * and check if bit was correctly setup or not.
 	 */
 	xspi->read_fn = xspi_read32;
 	xspi->write_fn = xspi_write32;

 	xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
 	tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
 	tmp &= XSPI_CR_LOOP;
 	if (tmp != XSPI_CR_LOOP) {
 		xspi->read_fn = xspi_read32_be;
 		xspi->write_fn = xspi_write32_be;
 	}

 	master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word);
 	xspi->bits_per_word = bits_per_word;
 	if (xspi->bits_per_word == 8) {
 		xspi->tx_fn = xspi_tx8;
 		xspi->rx_fn = xspi_rx8;
 	} else if (xspi->bits_per_word == 16) {
 		xspi->tx_fn = xspi_tx16;
 		xspi->rx_fn = xspi_rx16;
 	} else if (xspi->bits_per_word == 32) {
 		xspi->tx_fn = xspi_tx32;
 		xspi->rx_fn = xspi_rx32;
 	} else {
 		ret = -EINVAL;
 		goto put_master;
 	}

 	/* SPI controller initializations */
 	xspi_init_hw(xspi);

 	xspi->irq = platform_get_irq(pdev, 0);
 	if (xspi->irq < 0) {
 		ret = xspi->irq;
 		goto put_master;
 	}

 	/* Register for SPI Interrupt */
 	ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
 			       dev_name(&pdev->dev), xspi);
 	if (ret)
 		goto put_master;

 	ret = spi_bitbang_start(&xspi->bitbang);
 	if (ret) {
 		dev_err(&pdev->dev, "spi_bitbang_start FAILED\n");
 		goto put_master;
 	}

 	dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
 		(unsigned long long)res->start, xspi->regs, xspi->irq);

 	if (pdata) {
 		for (i = 0; i < pdata->num_devices; i++)
 			spi_new_device(master, pdata->devices + i);
 	}

 	platform_set_drvdata(pdev, master);
 	return 0;

 put_master:
 	spi_master_put(master);

 	return ret;
 }

 static int xilinx_spi_remove(struct platform_device *pdev)
 {
 	struct spi_master *master = platform_get_drvdata(pdev);
 	struct xilinx_spi *xspi = spi_master_get_devdata(master);
 	void __iomem *regs_base = xspi->regs;

 	spi_bitbang_stop(&xspi->bitbang);

 	/* Disable all the interrupts just in case */
 	xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
 	/* Disable the global IPIF interrupt */
 	xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);

 	spi_master_put(xspi->bitbang.master);

 	return 0;
 }

 /* work with hotplug and coldplug */
 MODULE_ALIAS("platform:" XILINX_SPI_NAME);

 static struct platform_driver xilinx_spi_driver = {
 	.probe = xilinx_spi_probe,
 	.remove = xilinx_spi_remove,
 	.driver = {
 		.name = XILINX_SPI_NAME,
 		.of_match_table = xilinx_spi_of_match,
 	},
 };
 module_platform_driver(xilinx_spi_driver);

 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
 MODULE_DESCRIPTION("Xilinx SPI driver");
 MODULE_LICENSE("GPL");
	/*
	* Xilinx SPI controller driver (master mode only)
	*
	* Author: MontaVista Software, Inc.
	* source@mvista.com
	*
	* Copyright (c) 2010 Secret Lab Technologies, Ltd.
	* Copyright (c) 2009 Intel Corporation
	* 2002-2007 (c) MontaVista Software, Inc.

	* 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.
	*/

	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/spi_bitbang.h>
	#include <linux/spi/xilinx_spi.h>
	#include <linux/io.h>

	#define XILINX_SPI_NAME "xilinx_spi"

	/* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
	* Product Specification", DS464
	*/
	#define XSPI_CR_OFFSET 0x60 /* Control Register */

	#define XSPI_CR_LOOP 0x01
	#define XSPI_CR_ENABLE 0x02
	#define XSPI_CR_MASTER_MODE 0x04
	#define XSPI_CR_CPOL 0x08
	#define XSPI_CR_CPHA 0x10
	#define XSPI_CR_MODE_MASK (XSPI_CR_CPHA \| XSPI_CR_CPOL)
	#define XSPI_CR_TXFIFO_RESET 0x20
	#define XSPI_CR_RXFIFO_RESET 0x40
	#define XSPI_CR_MANUAL_SSELECT 0x80
	#define XSPI_CR_TRANS_INHIBIT 0x100
	#define XSPI_CR_LSB_FIRST 0x200

	#define XSPI_SR_OFFSET 0x64 /* Status Register */

	#define XSPI_SR_RX_EMPTY_MASK 0x01 /* Receive FIFO is empty */
	#define XSPI_SR_RX_FULL_MASK 0x02 /* Receive FIFO is full */
	#define XSPI_SR_TX_EMPTY_MASK 0x04 /* Transmit FIFO is empty */
	#define XSPI_SR_TX_FULL_MASK 0x08 /* Transmit FIFO is full */
	#define XSPI_SR_MODE_FAULT_MASK 0x10 /* Mode fault error */

	#define XSPI_TXD_OFFSET 0x68 /* Data Transmit Register */
	#define XSPI_RXD_OFFSET 0x6c /* Data Receive Register */

	#define XSPI_SSR_OFFSET 0x70 /* 32-bit Slave Select Register */

	/* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
	* IPIF registers are 32 bit
	*/
	#define XIPIF_V123B_DGIER_OFFSET 0x1c /* IPIF global int enable reg */
	#define XIPIF_V123B_GINTR_ENABLE 0x80000000

	#define XIPIF_V123B_IISR_OFFSET 0x20 /* IPIF interrupt status reg */
	#define XIPIF_V123B_IIER_OFFSET 0x28 /* IPIF interrupt enable reg */

	#define XSPI_INTR_MODE_FAULT 0x01 /* Mode fault error */
	#define XSPI_INTR_SLAVE_MODE_FAULT 0x02 /* Selected as slave while
	* disabled */
	#define XSPI_INTR_TX_EMPTY 0x04 /* TxFIFO is empty */
	#define XSPI_INTR_TX_UNDERRUN 0x08 /* TxFIFO was underrun */
	#define XSPI_INTR_RX_FULL 0x10 /* RxFIFO is full */
	#define XSPI_INTR_RX_OVERRUN 0x20 /* RxFIFO was overrun */
	#define XSPI_INTR_TX_HALF_EMPTY 0x40 /* TxFIFO is half empty */

	#define XIPIF_V123B_RESETR_OFFSET 0x40 /* IPIF reset register */
	#define XIPIF_V123B_RESET_MASK 0x0a /* the value to write */

	struct xilinx_spi {
	/* bitbang has to be first */
	struct spi_bitbang bitbang;
	struct completion done;
	void __iomem regs; / virt. address of the control registers */

	int irq;

	u8 rx_ptr; / pointer in the Tx buffer */
	const u8 tx_ptr; / pointer in the Rx buffer */
	int remaining_bytes; /* the number of bytes left to transfer */
	u8 bits_per_word;
	unsigned int (read_fn)(void __iomem );
	void (write_fn)(u32, void __iomem );
	void (tx_fn)(struct xilinx_spi );
	void (rx_fn)(struct xilinx_spi );
	};

	static void xspi_write32(u32 val, void __iomem *addr)
	{
	iowrite32(val, addr);
	}

	static unsigned int xspi_read32(void __iomem *addr)
	{
	return ioread32(addr);
	}

	static void xspi_write32_be(u32 val, void __iomem *addr)
	{
	iowrite32be(val, addr);
	}

	static unsigned int xspi_read32_be(void __iomem *addr)
	{
	return ioread32be(addr);
	}

	static void xspi_tx8(struct xilinx_spi *xspi)
	{
	xspi->write_fn(*xspi->tx_ptr, xspi->regs + XSPI_TXD_OFFSET);
	xspi->tx_ptr++;
	}

	static void xspi_tx16(struct xilinx_spi *xspi)
	{
	xspi->write_fn((u16 )(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
	xspi->tx_ptr += 2;
	}

	static void xspi_tx32(struct xilinx_spi *xspi)
	{
	xspi->write_fn((u32 )(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
	xspi->tx_ptr += 4;
	}

	static void xspi_rx8(struct xilinx_spi *xspi)
	{
	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
	if (xspi->rx_ptr) {
	*xspi->rx_ptr = data & 0xff;
	xspi->rx_ptr++;
	}
	}

	static void xspi_rx16(struct xilinx_spi *xspi)
	{
	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
	if (xspi->rx_ptr) {
	(u16 )(xspi->rx_ptr) = data & 0xffff;
	xspi->rx_ptr += 2;
	}
	}

	static void xspi_rx32(struct xilinx_spi *xspi)
	{
	u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
	if (xspi->rx_ptr) {
	(u32 )(xspi->rx_ptr) = data;
	xspi->rx_ptr += 4;
	}
	}

	static void xspi_init_hw(struct xilinx_spi *xspi)
	{
	void __iomem *regs_base = xspi->regs;

	/* Reset the SPI device */
	xspi->write_fn(XIPIF_V123B_RESET_MASK,
	regs_base + XIPIF_V123B_RESETR_OFFSET);
	/* Disable all the interrupts just in case */
	xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
	/* Enable the global IPIF interrupt */
	xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
	regs_base + XIPIF_V123B_DGIER_OFFSET);
	/* Deselect the slave on the SPI bus */
	xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
	/* Disable the transmitter, enable Manual Slave Select Assertion,
	* put SPI controller into master mode, and enable it */
	xspi->write_fn(XSPI_CR_TRANS_INHIBIT \| XSPI_CR_MANUAL_SSELECT \|
	XSPI_CR_MASTER_MODE \| XSPI_CR_ENABLE \| XSPI_CR_TXFIFO_RESET \|
	XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET);
	}

	static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
	{
	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);

	if (is_on == BITBANG_CS_INACTIVE) {
	/* Deselect the slave on the SPI bus */
	xspi->write_fn(0xffff, xspi->regs + XSPI_SSR_OFFSET);
	} else if (is_on == BITBANG_CS_ACTIVE) {
	/* Set the SPI clock phase and polarity */
	u16 cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET)
	& ~XSPI_CR_MODE_MASK;
	if (spi->mode & SPI_CPHA)
	cr \|= XSPI_CR_CPHA;
	if (spi->mode & SPI_CPOL)
	cr \|= XSPI_CR_CPOL;
	xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);

	/* We do not check spi->max_speed_hz here as the SPI clock
	* frequency is not software programmable (the IP block design
	* parameter)
	*/

	/* Activate the chip select */
	xspi->write_fn(~(0x0001 << spi->chip_select),
	xspi->regs + XSPI_SSR_OFFSET);
	}
	}

	/* spi_bitbang requires custom setup_transfer() to be defined if there is a
	* custom txrx_bufs().
	*/
	static int xilinx_spi_setup_transfer(struct spi_device *spi,
	struct spi_transfer *t)
	{
	return 0;
	}

	static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi)
	{
	u8 sr;

	/* Fill the Tx FIFO with as many bytes as possible */
	sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
	while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) {
	if (xspi->tx_ptr)
	xspi->tx_fn(xspi);
	else
	xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
	xspi->remaining_bytes -= xspi->bits_per_word / 8;
	sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
	}
	}

	static int xilinx_spi_txrx_bufs(struct spi_device spi, struct spi_transfer t)
	{
	struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
	u32 ipif_ier;

	/* We get here with transmitter inhibited */

	xspi->tx_ptr = t->tx_buf;
	xspi->rx_ptr = t->rx_buf;
	xspi->remaining_bytes = t->len;
	reinit_completion(&xspi->done);


	/* Enable the transmit empty interrupt, which we use to determine
	* progress on the transmission.
	*/
	ipif_ier = xspi->read_fn(xspi->regs + XIPIF_V123B_IIER_OFFSET);
	xspi->write_fn(ipif_ier \| XSPI_INTR_TX_EMPTY,
	xspi->regs + XIPIF_V123B_IIER_OFFSET);

	for (;;) {
	u16 cr;
	u8 sr;

	xilinx_spi_fill_tx_fifo(xspi);

	/* Start the transfer by not inhibiting the transmitter any
	* longer
	*/
	cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
	~XSPI_CR_TRANS_INHIBIT;
	xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);

	wait_for_completion(&xspi->done);

	/* A transmit has just completed. Process received data and
	* check for more data to transmit. Always inhibit the
	* transmitter while the Isr refills the transmit register/FIFO,
	* or make sure it is stopped if we're done.
	*/
	cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
	xspi->write_fn(cr \| XSPI_CR_TRANS_INHIBIT,
	xspi->regs + XSPI_CR_OFFSET);

	/* Read out all the data from the Rx FIFO */
	sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
	while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
	xspi->rx_fn(xspi);
	sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
	}

	/* See if there is more data to send */
	if (xspi->remaining_bytes <= 0)
	break;
	}

	/* Disable the transmit empty interrupt */
	xspi->write_fn(ipif_ier, xspi->regs + XIPIF_V123B_IIER_OFFSET);

	return t->len - xspi->remaining_bytes;
	}


	/* This driver supports single master mode only. Hence Tx FIFO Empty
	* is the only interrupt we care about.
	* Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
	* Fault are not to happen.
	*/
	static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
	{
	struct xilinx_spi *xspi = dev_id;
	u32 ipif_isr;

	/* Get the IPIF interrupts, and clear them immediately */
	ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
	xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);

	if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */
	complete(&xspi->done);
	}

	return IRQ_HANDLED;
	}

	static const struct of_device_id xilinx_spi_of_match[] = {
	{ .compatible = "xlnx,xps-spi-2.00.a", },
	{ .compatible = "xlnx,xps-spi-2.00.b", },
	{}
	};
	MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);

	static int xilinx_spi_probe(struct platform_device *pdev)
	{
	struct xilinx_spi *xspi;
	struct xspi_platform_data *pdata;
	struct resource *res;
	int ret, num_cs = 0, bits_per_word = 8;
	struct spi_master *master;
	u32 tmp;
	u8 i;

	pdata = dev_get_platdata(&pdev->dev);
	if (pdata) {
	num_cs = pdata->num_chipselect;
	bits_per_word = pdata->bits_per_word;
	} else {
	of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits",
	&num_cs);
	}

	if (!num_cs) {
	dev_err(&pdev->dev,
	"Missing slave select configuration data\n");
	return -EINVAL;
	}

	master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi));
	if (!master)
	return -ENODEV;

	/* the spi->mode bits understood by this driver: */
	master->mode_bits = SPI_CPOL \| SPI_CPHA;

	xspi = spi_master_get_devdata(master);
	xspi->bitbang.master = master;
	xspi->bitbang.chipselect = xilinx_spi_chipselect;
	xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
	xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
	init_completion(&xspi->done);

	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 put_master;
	}

	master->bus_num = pdev->id;
	master->num_chipselect = num_cs;
	master->dev.of_node = pdev->dev.of_node;

	/*
	* Detect endianess on the IP via loop bit in CR. Detection
	* must be done before reset is sent because incorrect reset
	* value generates error interrupt.
	* Setup little endian helper functions first and try to use them
	* and check if bit was correctly setup or not.
	*/
	xspi->read_fn = xspi_read32;
	xspi->write_fn = xspi_write32;

	xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
	tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
	tmp &= XSPI_CR_LOOP;
	if (tmp != XSPI_CR_LOOP) {
	xspi->read_fn = xspi_read32_be;
	xspi->write_fn = xspi_write32_be;
	}

	master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word);
	xspi->bits_per_word = bits_per_word;
	if (xspi->bits_per_word == 8) {
	xspi->tx_fn = xspi_tx8;
	xspi->rx_fn = xspi_rx8;
	} else if (xspi->bits_per_word == 16) {
	xspi->tx_fn = xspi_tx16;
	xspi->rx_fn = xspi_rx16;
	} else if (xspi->bits_per_word == 32) {
	xspi->tx_fn = xspi_tx32;
	xspi->rx_fn = xspi_rx32;
	} else {
	ret = -EINVAL;
	goto put_master;
	}

	/* SPI controller initializations */
	xspi_init_hw(xspi);

	xspi->irq = platform_get_irq(pdev, 0);
	if (xspi->irq < 0) {
	ret = xspi->irq;
	goto put_master;
	}

	/* Register for SPI Interrupt */
	ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
	dev_name(&pdev->dev), xspi);
	if (ret)
	goto put_master;

	ret = spi_bitbang_start(&xspi->bitbang);
	if (ret) {
	dev_err(&pdev->dev, "spi_bitbang_start FAILED\n");
	goto put_master;
	}

	dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
	(unsigned long long)res->start, xspi->regs, xspi->irq);

	if (pdata) {
	for (i = 0; i < pdata->num_devices; i++)
	spi_new_device(master, pdata->devices + i);
	}

	platform_set_drvdata(pdev, master);
	return 0;

	put_master:
	spi_master_put(master);

	return ret;
	}

	static int xilinx_spi_remove(struct platform_device *pdev)
	{
	struct spi_master *master = platform_get_drvdata(pdev);
	struct xilinx_spi *xspi = spi_master_get_devdata(master);
	void __iomem *regs_base = xspi->regs;

	spi_bitbang_stop(&xspi->bitbang);

	/* Disable all the interrupts just in case */
	xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
	/* Disable the global IPIF interrupt */
	xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);

	spi_master_put(xspi->bitbang.master);

	return 0;
	}

	/* work with hotplug and coldplug */
	MODULE_ALIAS("platform:" XILINX_SPI_NAME);

	static struct platform_driver xilinx_spi_driver = {
	.probe = xilinx_spi_probe,
	.remove = xilinx_spi_remove,
	.driver = {
	.name = XILINX_SPI_NAME,
	.of_match_table = xilinx_spi_of_match,
	},
	};
	module_platform_driver(xilinx_spi_driver);

	MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
	MODULE_DESCRIPTION("Xilinx SPI driver");
	MODULE_LICENSE("GPL");