drivers/spi/spi-s3c24xx.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2006 Ben Dooks
  * Copyright 2006-2009 Simtec Electronics
  *	Ben Dooks <ben@simtec.co.uk>
 */

 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/slab.h>

 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/spi/s3c24xx.h>
 #include <linux/spi/s3c24xx-fiq.h>
 #include <linux/module.h>

 #include <asm/fiq.h>

 #include "spi-s3c24xx-regs.h"

 /**
  * struct s3c24xx_spi_devstate - per device data
  * @hz: Last frequency calculated for @sppre field.
  * @mode: Last mode setting for the @spcon field.
  * @spcon: Value to write to the SPCON register.
  * @sppre: Value to write to the SPPRE register.
  */
 struct s3c24xx_spi_devstate {
 	unsigned int	hz;
 	unsigned int	mode;
 	u8		spcon;
 	u8		sppre;
 };

 enum spi_fiq_mode {
 	FIQ_MODE_NONE	= 0,
 	FIQ_MODE_TX	= 1,
 	FIQ_MODE_RX	= 2,
 	FIQ_MODE_TXRX	= 3,
 };

 struct s3c24xx_spi {
 	/* bitbang has to be first */
 	struct spi_bitbang	 bitbang;
 	struct completion	 done;

 	void __iomem		*regs;
 	int			 irq;
 	int			 len;
 	int			 count;

 	struct fiq_handler	 fiq_handler;
 	enum spi_fiq_mode	 fiq_mode;
 	unsigned char		 fiq_inuse;
 	unsigned char		 fiq_claimed;

 	/* data buffers */
 	const unsigned char	*tx;
 	unsigned char		*rx;

 	struct clk		*clk;
 	struct spi_master	*master;
 	struct spi_device	*curdev;
 	struct device		*dev;
 	struct s3c2410_spi_info *pdata;
 };

 #define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
 #define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)

 static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev)
 {
 	return spi_master_get_devdata(sdev->master);
 }

 static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
 {
 	struct s3c24xx_spi_devstate *cs = spi->controller_state;
 	struct s3c24xx_spi *hw = to_hw(spi);

 	/* change the chipselect state and the state of the spi engine clock */

 	switch (value) {
 	case BITBANG_CS_INACTIVE:
 		writeb(cs->spcon, hw->regs + S3C2410_SPCON);
 		break;

 	case BITBANG_CS_ACTIVE:
 		writeb(cs->spcon | S3C2410_SPCON_ENSCK,
 		       hw->regs + S3C2410_SPCON);
 		break;
 	}
 }

 static int s3c24xx_spi_update_state(struct spi_device *spi,
 				    struct spi_transfer *t)
 {
 	struct s3c24xx_spi *hw = to_hw(spi);
 	struct s3c24xx_spi_devstate *cs = spi->controller_state;
 	unsigned int hz;
 	unsigned int div;
 	unsigned long clk;

 	hz  = t ? t->speed_hz : spi->max_speed_hz;

 	if (!hz)
 		hz = spi->max_speed_hz;

 	if (spi->mode != cs->mode) {
 		u8 spcon = SPCON_DEFAULT | S3C2410_SPCON_ENSCK;

 		if (spi->mode & SPI_CPHA)
 			spcon |= S3C2410_SPCON_CPHA_FMTB;

 		if (spi->mode & SPI_CPOL)
 			spcon |= S3C2410_SPCON_CPOL_HIGH;

 		cs->mode = spi->mode;
 		cs->spcon = spcon;
 	}

 	if (cs->hz != hz) {
 		clk = clk_get_rate(hw->clk);
 		div = DIV_ROUND_UP(clk, hz * 2) - 1;

 		if (div > 255)
 			div = 255;

 		dev_dbg(&spi->dev, "pre-scaler=%d (wanted %d, got %ld)\n",
 			div, hz, clk / (2 * (div + 1)));

 		cs->hz = hz;
 		cs->sppre = div;
 	}

 	return 0;
 }

 static int s3c24xx_spi_setupxfer(struct spi_device *spi,
 				 struct spi_transfer *t)
 {
 	struct s3c24xx_spi_devstate *cs = spi->controller_state;
 	struct s3c24xx_spi *hw = to_hw(spi);
 	int ret;

 	ret = s3c24xx_spi_update_state(spi, t);
 	if (!ret)
 		writeb(cs->sppre, hw->regs + S3C2410_SPPRE);

 	return ret;
 }

 static int s3c24xx_spi_setup(struct spi_device *spi)
 {
 	struct s3c24xx_spi_devstate *cs = spi->controller_state;
 	struct s3c24xx_spi *hw = to_hw(spi);
 	int ret;

 	/* allocate settings on the first call */
 	if (!cs) {
 		cs = devm_kzalloc(&spi->dev,
 				  sizeof(struct s3c24xx_spi_devstate),
 				  GFP_KERNEL);
 		if (!cs)
 			return -ENOMEM;

 		cs->spcon = SPCON_DEFAULT;
 		cs->hz = -1;
 		spi->controller_state = cs;
 	}

 	/* initialise the state from the device */
 	ret = s3c24xx_spi_update_state(spi, NULL);
 	if (ret)
 		return ret;

 	mutex_lock(&hw->bitbang.lock);
 	if (!hw->bitbang.busy) {
 		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
 		/* need to ndelay for 0.5 clocktick ? */
 	}
 	mutex_unlock(&hw->bitbang.lock);

 	return 0;
 }

 static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
 {
 	return hw->tx ? hw->tx[count] : 0;
 }

 #ifdef CONFIG_SPI_S3C24XX_FIQ
 /* Support for FIQ based pseudo-DMA to improve the transfer speed.
  *
  * This code uses the assembly helper in spi_s3c24xx_spi.S which is
  * used by the FIQ core to move data between main memory and the peripheral
  * block. Since this is code running on the processor, there is no problem
  * with cache coherency of the buffers, so we can use any buffer we like.
  */

 /**
  * struct spi_fiq_code - FIQ code and header
  * @length: The length of the code fragment, excluding this header.
  * @ack_offset: The offset from @data to the word to place the IRQ ACK bit at.
  * @data: The code itself to install as a FIQ handler.
  */
 struct spi_fiq_code {
 	u32	length;
 	u32	ack_offset;
 	u8	data[];
 };

 /**
  * s3c24xx_spi_tryfiq - attempt to claim and setup FIQ for transfer
  * @hw: The hardware state.
  *
  * Claim the FIQ handler (only one can be active at any one time) and
  * then setup the correct transfer code for this transfer.
  *
  * This call updates all the necessary state information if successful,
  * so the caller does not need to do anything more than start the transfer
  * as normal, since the IRQ will have been re-routed to the FIQ handler.
 */
 static void s3c24xx_spi_tryfiq(struct s3c24xx_spi *hw)
 {
 	struct pt_regs regs;
 	enum spi_fiq_mode mode;
 	struct spi_fiq_code *code;
 	u32 *ack_ptr = NULL;
 	int ret;

 	if (!hw->fiq_claimed) {
 		/* try and claim fiq if we haven't got it, and if not
 		 * then return and simply use another transfer method */

 		ret = claim_fiq(&hw->fiq_handler);
 		if (ret)
 			return;
 	}

 	if (hw->tx && !hw->rx)
 		mode = FIQ_MODE_TX;
 	else if (hw->rx && !hw->tx)
 		mode = FIQ_MODE_RX;
 	else
 		mode = FIQ_MODE_TXRX;

 	regs.uregs[fiq_rspi] = (long)hw->regs;
 	regs.uregs[fiq_rrx]  = (long)hw->rx;
 	regs.uregs[fiq_rtx]  = (long)hw->tx + 1;
 	regs.uregs[fiq_rcount] = hw->len - 1;

 	set_fiq_regs(&regs);

 	if (hw->fiq_mode != mode) {
 		hw->fiq_mode = mode;

 		switch (mode) {
 		case FIQ_MODE_TX:
 			code = &s3c24xx_spi_fiq_tx;
 			break;
 		case FIQ_MODE_RX:
 			code = &s3c24xx_spi_fiq_rx;
 			break;
 		case FIQ_MODE_TXRX:
 			code = &s3c24xx_spi_fiq_txrx;
 			break;
 		default:
 			code = NULL;
 		}

 		BUG_ON(!code);

 		ack_ptr = (u32 *)&code->data[code->ack_offset];
 		set_fiq_handler(&code->data, code->length);
 	}

 	s3c24xx_set_fiq(hw->irq, ack_ptr, true);

 	hw->fiq_mode = mode;
 	hw->fiq_inuse = 1;
 }

 /**
  * s3c24xx_spi_fiqop - FIQ core code callback
  * @pw: Data registered with the handler
  * @release: Whether this is a release or a return.
  *
  * Called by the FIQ code when another module wants to use the FIQ, so
  * return whether we are currently using this or not and then update our
  * internal state.
  */
 static int s3c24xx_spi_fiqop(void *pw, int release)
 {
 	struct s3c24xx_spi *hw = pw;
 	int ret = 0;

 	if (release) {
 		if (hw->fiq_inuse)
 			ret = -EBUSY;

 		/* note, we do not need to unroute the FIQ, as the FIQ
 		 * vector code de-routes it to signal the end of transfer */

 		hw->fiq_mode = FIQ_MODE_NONE;
 		hw->fiq_claimed = 0;
 	} else {
 		hw->fiq_claimed = 1;
 	}

 	return ret;
 }

 /**
  * s3c24xx_spi_initfiq - setup the information for the FIQ core
  * @hw: The hardware state.
  *
  * Setup the fiq_handler block to pass to the FIQ core.
  */
 static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *hw)
 {
 	hw->fiq_handler.dev_id = hw;
 	hw->fiq_handler.name = dev_name(hw->dev);
 	hw->fiq_handler.fiq_op = s3c24xx_spi_fiqop;
 }

 /**
  * s3c24xx_spi_usefiq - return if we should be using FIQ.
  * @hw: The hardware state.
  *
  * Return true if the platform data specifies whether this channel is
  * allowed to use the FIQ.
  */
 static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *hw)
 {
 	return hw->pdata->use_fiq;
 }

 /**
  * s3c24xx_spi_usingfiq - return if channel is using FIQ
  * @spi: The hardware state.
  *
  * Return whether the channel is currently using the FIQ (separate from
  * whether the FIQ is claimed).
  */
 static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *spi)
 {
 	return spi->fiq_inuse;
 }
 #else

 static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *s) { }
 static inline void s3c24xx_spi_tryfiq(struct s3c24xx_spi *s) { }
 static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *s) { return false; }
 static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *s) { return false; }

 #endif /* CONFIG_SPI_S3C24XX_FIQ */

 static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 {
 	struct s3c24xx_spi *hw = to_hw(spi);

 	hw->tx = t->tx_buf;
 	hw->rx = t->rx_buf;
 	hw->len = t->len;
 	hw->count = 0;

 	init_completion(&hw->done);

 	hw->fiq_inuse = 0;
 	if (s3c24xx_spi_usefiq(hw) && t->len >= 3)
 		s3c24xx_spi_tryfiq(hw);

 	/* send the first byte */
 	writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);

 	wait_for_completion(&hw->done);
 	return hw->count;
 }

 static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
 {
 	struct s3c24xx_spi *hw = dev;
 	unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
 	unsigned int count = hw->count;

 	if (spsta & S3C2410_SPSTA_DCOL) {
 		dev_dbg(hw->dev, "data-collision\n");
 		complete(&hw->done);
 		goto irq_done;
 	}

 	if (!(spsta & S3C2410_SPSTA_READY)) {
 		dev_dbg(hw->dev, "spi not ready for tx?\n");
 		complete(&hw->done);
 		goto irq_done;
 	}

 	if (!s3c24xx_spi_usingfiq(hw)) {
 		hw->count++;

 		if (hw->rx)
 			hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);

 		count++;

 		if (count < hw->len)
 			writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
 		else
 			complete(&hw->done);
 	} else {
 		hw->count = hw->len;
 		hw->fiq_inuse = 0;

 		if (hw->rx)
 			hw->rx[hw->len-1] = readb(hw->regs + S3C2410_SPRDAT);

 		complete(&hw->done);
 	}

  irq_done:
 	return IRQ_HANDLED;
 }

 static void s3c24xx_spi_initialsetup(struct s3c24xx_spi *hw)
 {
 	/* for the moment, permanently enable the clock */

 	clk_enable(hw->clk);

 	/* program defaults into the registers */

 	writeb(0xff, hw->regs + S3C2410_SPPRE);
 	writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
 	writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);
 }

 static int s3c24xx_spi_probe(struct platform_device *pdev)
 {
 	struct s3c2410_spi_info *pdata;
 	struct s3c24xx_spi *hw;
 	struct spi_master *master;
 	int err = 0;

 	master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
 	if (master == NULL) {
 		dev_err(&pdev->dev, "No memory for spi_master\n");
 		return -ENOMEM;
 	}

 	hw = spi_master_get_devdata(master);

 	hw->master = master;
 	hw->pdata = pdata = dev_get_platdata(&pdev->dev);
 	hw->dev = &pdev->dev;

 	if (pdata == NULL) {
 		dev_err(&pdev->dev, "No platform data supplied\n");
 		err = -ENOENT;
 		goto err_no_pdata;
 	}

 	platform_set_drvdata(pdev, hw);
 	init_completion(&hw->done);

 	/* initialise fiq handler */

 	s3c24xx_spi_initfiq(hw);

 	/* setup the master state. */

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

 	master->num_chipselect = hw->pdata->num_cs;
 	master->bus_num = pdata->bus_num;
 	master->bits_per_word_mask = SPI_BPW_MASK(8);
 	/* we need to call the local chipselect callback */
 	master->flags = SPI_MASTER_GPIO_SS;
 	master->use_gpio_descriptors = true;

 	/* setup the state for the bitbang driver */

 	hw->bitbang.master         = hw->master;
 	hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
 	hw->bitbang.chipselect     = s3c24xx_spi_chipsel;
 	hw->bitbang.txrx_bufs      = s3c24xx_spi_txrx;

 	hw->master->setup  = s3c24xx_spi_setup;

 	dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);

 	/* find and map our resources */
 	hw->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(hw->regs)) {
 		err = PTR_ERR(hw->regs);
 		goto err_no_pdata;
 	}

 	hw->irq = platform_get_irq(pdev, 0);
 	if (hw->irq < 0) {
 		err = -ENOENT;
 		goto err_no_pdata;
 	}

 	err = devm_request_irq(&pdev->dev, hw->irq, s3c24xx_spi_irq, 0,
 				pdev->name, hw);
 	if (err) {
 		dev_err(&pdev->dev, "Cannot claim IRQ\n");
 		goto err_no_pdata;
 	}

 	hw->clk = devm_clk_get(&pdev->dev, "spi");
 	if (IS_ERR(hw->clk)) {
 		dev_err(&pdev->dev, "No clock for device\n");
 		err = PTR_ERR(hw->clk);
 		goto err_no_pdata;
 	}

 	s3c24xx_spi_initialsetup(hw);

 	/* register our spi controller */

 	err = spi_bitbang_start(&hw->bitbang);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to register SPI master\n");
 		goto err_register;
 	}

 	return 0;

  err_register:
 	clk_disable(hw->clk);

  err_no_pdata:
 	spi_master_put(hw->master);
 	return err;
 }

 static int s3c24xx_spi_remove(struct platform_device *dev)
 {
 	struct s3c24xx_spi *hw = platform_get_drvdata(dev);

 	spi_bitbang_stop(&hw->bitbang);
 	clk_disable(hw->clk);
 	spi_master_put(hw->master);
 	return 0;
 }


 #ifdef CONFIG_PM

 static int s3c24xx_spi_suspend(struct device *dev)
 {
 	struct s3c24xx_spi *hw = dev_get_drvdata(dev);
 	int ret;

 	ret = spi_master_suspend(hw->master);
 	if (ret)
 		return ret;

 	clk_disable(hw->clk);
 	return 0;
 }

 static int s3c24xx_spi_resume(struct device *dev)
 {
 	struct s3c24xx_spi *hw = dev_get_drvdata(dev);

 	s3c24xx_spi_initialsetup(hw);
 	return spi_master_resume(hw->master);
 }

 static const struct dev_pm_ops s3c24xx_spi_pmops = {
 	.suspend	= s3c24xx_spi_suspend,
 	.resume		= s3c24xx_spi_resume,
 };

 #define S3C24XX_SPI_PMOPS &s3c24xx_spi_pmops
 #else
 #define S3C24XX_SPI_PMOPS NULL
 #endif /* CONFIG_PM */

 MODULE_ALIAS("platform:s3c2410-spi");
 static struct platform_driver s3c24xx_spi_driver = {
 	.probe		= s3c24xx_spi_probe,
 	.remove		= s3c24xx_spi_remove,
 	.driver		= {
 		.name	= "s3c2410-spi",
 		.pm	= S3C24XX_SPI_PMOPS,
 	},
 };
 module_platform_driver(s3c24xx_spi_driver);

 MODULE_DESCRIPTION("S3C24XX SPI Driver");
 MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (c) 2006 Ben Dooks
	* Copyright 2006-2009 Simtec Electronics
	* Ben Dooks <ben@simtec.co.uk>
	*/

	#include <linux/spinlock.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/err.h>
	#include <linux/clk.h>
	#include <linux/platform_device.h>
	#include <linux/io.h>
	#include <linux/slab.h>

	#include <linux/spi/spi.h>
	#include <linux/spi/spi_bitbang.h>
	#include <linux/spi/s3c24xx.h>
	#include <linux/spi/s3c24xx-fiq.h>
	#include <linux/module.h>

	#include <asm/fiq.h>

	#include "spi-s3c24xx-regs.h"

	/**
	* struct s3c24xx_spi_devstate - per device data
	* @hz: Last frequency calculated for @sppre field.
	* @mode: Last mode setting for the @spcon field.
	* @spcon: Value to write to the SPCON register.
	* @sppre: Value to write to the SPPRE register.
	*/
	struct s3c24xx_spi_devstate {
	unsigned int hz;
	unsigned int mode;
	u8 spcon;
	u8 sppre;
	};

	enum spi_fiq_mode {
	FIQ_MODE_NONE = 0,
	FIQ_MODE_TX = 1,
	FIQ_MODE_RX = 2,
	FIQ_MODE_TXRX = 3,
	};

	struct s3c24xx_spi {
	/* bitbang has to be first */
	struct spi_bitbang bitbang;
	struct completion done;

	void __iomem *regs;
	int irq;
	int len;
	int count;

	struct fiq_handler fiq_handler;
	enum spi_fiq_mode fiq_mode;
	unsigned char fiq_inuse;
	unsigned char fiq_claimed;

	/* data buffers */
	const unsigned char *tx;
	unsigned char *rx;

	struct clk *clk;
	struct spi_master *master;
	struct spi_device *curdev;
	struct device *dev;
	struct s3c2410_spi_info *pdata;
	};

	#define SPCON_DEFAULT (S3C2410_SPCON_MSTR \| S3C2410_SPCON_SMOD_INT)
	#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)

	static inline struct s3c24xx_spi to_hw(struct spi_device sdev)
	{
	return spi_master_get_devdata(sdev->master);
	}

	static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
	{
	struct s3c24xx_spi_devstate *cs = spi->controller_state;
	struct s3c24xx_spi *hw = to_hw(spi);

	/* change the chipselect state and the state of the spi engine clock */

	switch (value) {
	case BITBANG_CS_INACTIVE:
	writeb(cs->spcon, hw->regs + S3C2410_SPCON);
	break;

	case BITBANG_CS_ACTIVE:
	writeb(cs->spcon \| S3C2410_SPCON_ENSCK,
	hw->regs + S3C2410_SPCON);
	break;
	}
	}

	static int s3c24xx_spi_update_state(struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct s3c24xx_spi *hw = to_hw(spi);
	struct s3c24xx_spi_devstate *cs = spi->controller_state;
	unsigned int hz;
	unsigned int div;
	unsigned long clk;

	hz = t ? t->speed_hz : spi->max_speed_hz;

	if (!hz)
	hz = spi->max_speed_hz;

	if (spi->mode != cs->mode) {
	u8 spcon = SPCON_DEFAULT \| S3C2410_SPCON_ENSCK;

	if (spi->mode & SPI_CPHA)
	spcon \|= S3C2410_SPCON_CPHA_FMTB;

	if (spi->mode & SPI_CPOL)
	spcon \|= S3C2410_SPCON_CPOL_HIGH;

	cs->mode = spi->mode;
	cs->spcon = spcon;
	}

	if (cs->hz != hz) {
	clk = clk_get_rate(hw->clk);
	div = DIV_ROUND_UP(clk, hz * 2) - 1;

	if (div > 255)
	div = 255;

	dev_dbg(&spi->dev, "pre-scaler=%d (wanted %d, got %ld)\n",
	div, hz, clk / (2 * (div + 1)));

	cs->hz = hz;
	cs->sppre = div;
	}

	return 0;
	}

	static int s3c24xx_spi_setupxfer(struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct s3c24xx_spi_devstate *cs = spi->controller_state;
	struct s3c24xx_spi *hw = to_hw(spi);
	int ret;

	ret = s3c24xx_spi_update_state(spi, t);
	if (!ret)
	writeb(cs->sppre, hw->regs + S3C2410_SPPRE);

	return ret;
	}

	static int s3c24xx_spi_setup(struct spi_device *spi)
	{
	struct s3c24xx_spi_devstate *cs = spi->controller_state;
	struct s3c24xx_spi *hw = to_hw(spi);
	int ret;

	/* allocate settings on the first call */
	if (!cs) {
	cs = devm_kzalloc(&spi->dev,
	sizeof(struct s3c24xx_spi_devstate),
	GFP_KERNEL);
	if (!cs)
	return -ENOMEM;

	cs->spcon = SPCON_DEFAULT;
	cs->hz = -1;
	spi->controller_state = cs;
	}

	/* initialise the state from the device */
	ret = s3c24xx_spi_update_state(spi, NULL);
	if (ret)
	return ret;

	mutex_lock(&hw->bitbang.lock);
	if (!hw->bitbang.busy) {
	hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
	/* need to ndelay for 0.5 clocktick ? */
	}
	mutex_unlock(&hw->bitbang.lock);

	return 0;
	}

	static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
	{
	return hw->tx ? hw->tx[count] : 0;
	}

	#ifdef CONFIG_SPI_S3C24XX_FIQ
	/* Support for FIQ based pseudo-DMA to improve the transfer speed.
	*
	* This code uses the assembly helper in spi_s3c24xx_spi.S which is
	* used by the FIQ core to move data between main memory and the peripheral
	* block. Since this is code running on the processor, there is no problem
	* with cache coherency of the buffers, so we can use any buffer we like.
	*/

	/**
	* struct spi_fiq_code - FIQ code and header
	* @length: The length of the code fragment, excluding this header.
	* @ack_offset: The offset from @data to the word to place the IRQ ACK bit at.
	* @data: The code itself to install as a FIQ handler.
	*/
	struct spi_fiq_code {
	u32 length;
	u32 ack_offset;
	u8 data[];
	};

	/**
	* s3c24xx_spi_tryfiq - attempt to claim and setup FIQ for transfer
	* @hw: The hardware state.
	*
	* Claim the FIQ handler (only one can be active at any one time) and
	* then setup the correct transfer code for this transfer.
	*
	* This call updates all the necessary state information if successful,
	* so the caller does not need to do anything more than start the transfer
	* as normal, since the IRQ will have been re-routed to the FIQ handler.
	*/
	static void s3c24xx_spi_tryfiq(struct s3c24xx_spi *hw)
	{
	struct pt_regs regs;
	enum spi_fiq_mode mode;
	struct spi_fiq_code *code;
	u32 *ack_ptr = NULL;
	int ret;

	if (!hw->fiq_claimed) {
	/* try and claim fiq if we haven't got it, and if not
	* then return and simply use another transfer method */

	ret = claim_fiq(&hw->fiq_handler);
	if (ret)
	return;
	}

	if (hw->tx && !hw->rx)
	mode = FIQ_MODE_TX;
	else if (hw->rx && !hw->tx)
	mode = FIQ_MODE_RX;
	else
	mode = FIQ_MODE_TXRX;

	regs.uregs[fiq_rspi] = (long)hw->regs;
	regs.uregs[fiq_rrx] = (long)hw->rx;
	regs.uregs[fiq_rtx] = (long)hw->tx + 1;
	regs.uregs[fiq_rcount] = hw->len - 1;

	set_fiq_regs(&regs);

	if (hw->fiq_mode != mode) {
	hw->fiq_mode = mode;

	switch (mode) {
	case FIQ_MODE_TX:
	code = &s3c24xx_spi_fiq_tx;
	break;
	case FIQ_MODE_RX:
	code = &s3c24xx_spi_fiq_rx;
	break;
	case FIQ_MODE_TXRX:
	code = &s3c24xx_spi_fiq_txrx;
	break;
	default:
	code = NULL;
	}

	BUG_ON(!code);

	ack_ptr = (u32 *)&code->data[code->ack_offset];
	set_fiq_handler(&code->data, code->length);
	}

	s3c24xx_set_fiq(hw->irq, ack_ptr, true);

	hw->fiq_mode = mode;
	hw->fiq_inuse = 1;
	}

	/**
	* s3c24xx_spi_fiqop - FIQ core code callback
	* @pw: Data registered with the handler
	* @release: Whether this is a release or a return.
	*
	* Called by the FIQ code when another module wants to use the FIQ, so
	* return whether we are currently using this or not and then update our
	* internal state.
	*/
	static int s3c24xx_spi_fiqop(void *pw, int release)
	{
	struct s3c24xx_spi *hw = pw;
	int ret = 0;

	if (release) {
	if (hw->fiq_inuse)
	ret = -EBUSY;

	/* note, we do not need to unroute the FIQ, as the FIQ
	* vector code de-routes it to signal the end of transfer */

	hw->fiq_mode = FIQ_MODE_NONE;
	hw->fiq_claimed = 0;
	} else {
	hw->fiq_claimed = 1;
	}

	return ret;
	}

	/**
	* s3c24xx_spi_initfiq - setup the information for the FIQ core
	* @hw: The hardware state.
	*
	* Setup the fiq_handler block to pass to the FIQ core.
	*/
	static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *hw)
	{
	hw->fiq_handler.dev_id = hw;
	hw->fiq_handler.name = dev_name(hw->dev);
	hw->fiq_handler.fiq_op = s3c24xx_spi_fiqop;
	}

	/**
	* s3c24xx_spi_usefiq - return if we should be using FIQ.
	* @hw: The hardware state.
	*
	* Return true if the platform data specifies whether this channel is
	* allowed to use the FIQ.
	*/
	static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *hw)
	{
	return hw->pdata->use_fiq;
	}

	/**
	* s3c24xx_spi_usingfiq - return if channel is using FIQ
	* @spi: The hardware state.
	*
	* Return whether the channel is currently using the FIQ (separate from
	* whether the FIQ is claimed).
	*/
	static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *spi)
	{
	return spi->fiq_inuse;
	}
	#else

	static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *s) { }
	static inline void s3c24xx_spi_tryfiq(struct s3c24xx_spi *s) { }
	static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *s) { return false; }
	static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *s) { return false; }

	#endif /* CONFIG_SPI_S3C24XX_FIQ */

	static int s3c24xx_spi_txrx(struct spi_device spi, struct spi_transfer t)
	{
	struct s3c24xx_spi *hw = to_hw(spi);

	hw->tx = t->tx_buf;
	hw->rx = t->rx_buf;
	hw->len = t->len;
	hw->count = 0;

	init_completion(&hw->done);

	hw->fiq_inuse = 0;
	if (s3c24xx_spi_usefiq(hw) && t->len >= 3)
	s3c24xx_spi_tryfiq(hw);

	/* send the first byte */
	writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);

	wait_for_completion(&hw->done);
	return hw->count;
	}

	static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
	{
	struct s3c24xx_spi *hw = dev;
	unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
	unsigned int count = hw->count;

	if (spsta & S3C2410_SPSTA_DCOL) {
	dev_dbg(hw->dev, "data-collision\n");
	complete(&hw->done);
	goto irq_done;
	}

	if (!(spsta & S3C2410_SPSTA_READY)) {
	dev_dbg(hw->dev, "spi not ready for tx?\n");
	complete(&hw->done);
	goto irq_done;
	}

	if (!s3c24xx_spi_usingfiq(hw)) {
	hw->count++;

	if (hw->rx)
	hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);

	count++;

	if (count < hw->len)
	writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
	else
	complete(&hw->done);
	} else {
	hw->count = hw->len;
	hw->fiq_inuse = 0;

	if (hw->rx)
	hw->rx[hw->len-1] = readb(hw->regs + S3C2410_SPRDAT);

	complete(&hw->done);
	}

	irq_done:
	return IRQ_HANDLED;
	}

	static void s3c24xx_spi_initialsetup(struct s3c24xx_spi *hw)
	{
	/* for the moment, permanently enable the clock */

	clk_enable(hw->clk);

	/* program defaults into the registers */

	writeb(0xff, hw->regs + S3C2410_SPPRE);
	writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
	writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);
	}

	static int s3c24xx_spi_probe(struct platform_device *pdev)
	{
	struct s3c2410_spi_info *pdata;
	struct s3c24xx_spi *hw;
	struct spi_master *master;
	int err = 0;

	master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
	if (master == NULL) {
	dev_err(&pdev->dev, "No memory for spi_master\n");
	return -ENOMEM;
	}

	hw = spi_master_get_devdata(master);

	hw->master = master;
	hw->pdata = pdata = dev_get_platdata(&pdev->dev);
	hw->dev = &pdev->dev;

	if (pdata == NULL) {
	dev_err(&pdev->dev, "No platform data supplied\n");
	err = -ENOENT;
	goto err_no_pdata;
	}

	platform_set_drvdata(pdev, hw);
	init_completion(&hw->done);

	/* initialise fiq handler */

	s3c24xx_spi_initfiq(hw);

	/* setup the master state. */

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

	master->num_chipselect = hw->pdata->num_cs;
	master->bus_num = pdata->bus_num;
	master->bits_per_word_mask = SPI_BPW_MASK(8);
	/* we need to call the local chipselect callback */
	master->flags = SPI_MASTER_GPIO_SS;
	master->use_gpio_descriptors = true;

	/* setup the state for the bitbang driver */

	hw->bitbang.master = hw->master;
	hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
	hw->bitbang.chipselect = s3c24xx_spi_chipsel;
	hw->bitbang.txrx_bufs = s3c24xx_spi_txrx;

	hw->master->setup = s3c24xx_spi_setup;

	dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);

	/* find and map our resources */
	hw->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(hw->regs)) {
	err = PTR_ERR(hw->regs);
	goto err_no_pdata;
	}

	hw->irq = platform_get_irq(pdev, 0);
	if (hw->irq < 0) {
	err = -ENOENT;
	goto err_no_pdata;
	}

	err = devm_request_irq(&pdev->dev, hw->irq, s3c24xx_spi_irq, 0,
	pdev->name, hw);
	if (err) {
	dev_err(&pdev->dev, "Cannot claim IRQ\n");
	goto err_no_pdata;
	}

	hw->clk = devm_clk_get(&pdev->dev, "spi");
	if (IS_ERR(hw->clk)) {
	dev_err(&pdev->dev, "No clock for device\n");
	err = PTR_ERR(hw->clk);
	goto err_no_pdata;
	}

	s3c24xx_spi_initialsetup(hw);

	/* register our spi controller */

	err = spi_bitbang_start(&hw->bitbang);
	if (err) {
	dev_err(&pdev->dev, "Failed to register SPI master\n");
	goto err_register;
	}

	return 0;

	err_register:
	clk_disable(hw->clk);

	err_no_pdata:
	spi_master_put(hw->master);
	return err;
	}

	static int s3c24xx_spi_remove(struct platform_device *dev)
	{
	struct s3c24xx_spi *hw = platform_get_drvdata(dev);

	spi_bitbang_stop(&hw->bitbang);
	clk_disable(hw->clk);
	spi_master_put(hw->master);
	return 0;
	}


	#ifdef CONFIG_PM

	static int s3c24xx_spi_suspend(struct device *dev)
	{
	struct s3c24xx_spi *hw = dev_get_drvdata(dev);
	int ret;

	ret = spi_master_suspend(hw->master);
	if (ret)
	return ret;

	clk_disable(hw->clk);
	return 0;
	}

	static int s3c24xx_spi_resume(struct device *dev)
	{
	struct s3c24xx_spi *hw = dev_get_drvdata(dev);

	s3c24xx_spi_initialsetup(hw);
	return spi_master_resume(hw->master);
	}

	static const struct dev_pm_ops s3c24xx_spi_pmops = {
	.suspend = s3c24xx_spi_suspend,
	.resume = s3c24xx_spi_resume,
	};

	#define S3C24XX_SPI_PMOPS &s3c24xx_spi_pmops
	#else
	#define S3C24XX_SPI_PMOPS NULL
	#endif /* CONFIG_PM */

	MODULE_ALIAS("platform:s3c2410-spi");
	static struct platform_driver s3c24xx_spi_driver = {
	.probe = s3c24xx_spi_probe,
	.remove = s3c24xx_spi_remove,
	.driver = {
	.name = "s3c2410-spi",
	.pm = S3C24XX_SPI_PMOPS,
	},
	};
	module_platform_driver(s3c24xx_spi_driver);

	MODULE_DESCRIPTION("S3C24XX SPI Driver");
	MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
	MODULE_LICENSE("GPL");