drivers/spi/spi-ti-ssp.c - kernel/msm-4.9 - Gitiles

 /*
  * Sequencer Serial Port (SSP) based SPI master driver
  *
  * Copyright (C) 2010 Texas Instruments Inc
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */

 #include <linux/kernel.h>
 #include <linux/err.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>
 #include <linux/mfd/ti_ssp.h>

 #define MODE_BITS	(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)

 struct ti_ssp_spi {
 	struct spi_master		*master;
 	struct device			*dev;
 	spinlock_t			lock;
 	struct list_head		msg_queue;
 	struct completion		complete;
 	bool				shutdown;
 	struct workqueue_struct		*workqueue;
 	struct work_struct		work;
 	u8				mode, bpw;
 	int				cs_active;
 	u32				pc_en, pc_dis, pc_wr, pc_rd;
 	void				(*select)(int cs);
 };

 static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
 {
 	u32 ret;

 	ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
 	return ret;
 }

 static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
 {
 	ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
 }

 static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
 		       struct spi_transfer *t)
 {
 	int count;

 	if (hw->bpw <= 8) {
 		u8		*rx = t->rx_buf;
 		const u8	*tx = t->tx_buf;

 		for (count = 0; count < t->len; count += 1) {
 			if (t->tx_buf)
 				ti_ssp_spi_tx(hw, *tx++);
 			if (t->rx_buf)
 				*rx++ = ti_ssp_spi_rx(hw);
 		}
 	} else if (hw->bpw <= 16) {
 		u16		*rx = t->rx_buf;
 		const u16	*tx = t->tx_buf;

 		for (count = 0; count < t->len; count += 2) {
 			if (t->tx_buf)
 				ti_ssp_spi_tx(hw, *tx++);
 			if (t->rx_buf)
 				*rx++ = ti_ssp_spi_rx(hw);
 		}
 	} else {
 		u32		*rx = t->rx_buf;
 		const u32	*tx = t->tx_buf;

 		for (count = 0; count < t->len; count += 4) {
 			if (t->tx_buf)
 				ti_ssp_spi_tx(hw, *tx++);
 			if (t->rx_buf)
 				*rx++ = ti_ssp_spi_rx(hw);
 		}
 	}

 	msg->actual_length += count; /* bytes transferred */

 	dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
 		t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
 		hw->bpw, count, (count < t->len) ? " (under)" : "");

 	return (count < t->len) ? -EIO : 0; /* left over data */
 }

 static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
 {
 	cs_active = !!cs_active;
 	if (cs_active == hw->cs_active)
 		return;
 	ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
 	hw->cs_active = cs_active;
 }

 #define __SHIFT_OUT(bits)	(SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
 				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
 #define __SHIFT_IN(bits)	(SSP_OPCODE_SHIFT | SSP_IN_MODE  | \
 				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))

 static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
 {
 	int error, idx = 0;
 	u32 seqram[16];
 	u32 cs_en, cs_dis, clk;
 	u32 topbits, botbits;

 	mode &= MODE_BITS;
 	if (mode == hw->mode && bpw == hw->bpw)
 		return 0;

 	cs_en  = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
 	cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW  : SSP_CS_HIGH;
 	clk    = (mode & SPI_CPOL)    ? SSP_CLK_HIGH : SSP_CLK_LOW;

 	/* Construct instructions */

 	/* Disable Chip Select */
 	hw->pc_dis = idx;
 	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
 	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_dis | clk;

 	/* Enable Chip Select */
 	hw->pc_en = idx;
 	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
 	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_en | clk;

 	/* Reads and writes need to be split for bpw > 16 */
 	topbits = (bpw > 16) ? 16 : bpw;
 	botbits = bpw - topbits;

 	/* Write */
 	hw->pc_wr = idx;
 	seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
 	if (botbits)
 		seqram[idx++] = __SHIFT_OUT(botbits)  | SSP_DATA_REG;
 	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;

 	/* Read */
 	hw->pc_rd = idx;
 	if (botbits)
 		seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
 	seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
 	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;

 	error = ti_ssp_load(hw->dev, 0, seqram, idx);
 	if (error < 0)
 		return error;

 	error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
 					  0 : SSP_EARLY_DIN));
 	if (error < 0)
 		return error;

 	hw->bpw = bpw;
 	hw->mode = mode;

 	return error;
 }

 static void ti_ssp_spi_work(struct work_struct *work)
 {
 	struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);

 	spin_lock(&hw->lock);

 	 while (!list_empty(&hw->msg_queue)) {
 		struct spi_message	*m;
 		struct spi_device	*spi;
 		struct spi_transfer	*t = NULL;
 		int			status = 0;

 		m = container_of(hw->msg_queue.next, struct spi_message,
 				 queue);

 		list_del_init(&m->queue);

 		spin_unlock(&hw->lock);

 		spi = m->spi;

 		if (hw->select)
 			hw->select(spi->chip_select);

 		list_for_each_entry(t, &m->transfers, transfer_list) {
 			int bpw = spi->bits_per_word;
 			int xfer_status;

 			if (t->bits_per_word)
 				bpw = t->bits_per_word;

 			if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
 				break;

 			ti_ssp_spi_chip_select(hw, 1);

 			xfer_status = ti_ssp_spi_txrx(hw, m, t);
 			if (xfer_status < 0)
 				status = xfer_status;

 			if (t->delay_usecs)
 				udelay(t->delay_usecs);

 			if (t->cs_change)
 				ti_ssp_spi_chip_select(hw, 0);
 		}

 		ti_ssp_spi_chip_select(hw, 0);
 		m->status = status;
 		m->complete(m->context);

 		spin_lock(&hw->lock);
 	}

 	if (hw->shutdown)
 		complete(&hw->complete);

 	spin_unlock(&hw->lock);
 }

 static int ti_ssp_spi_setup(struct spi_device *spi)
 {
 	if (spi->bits_per_word > 32)
 		return -EINVAL;

 	return 0;
 }

 static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
 {
 	struct ti_ssp_spi	*hw;
 	struct spi_transfer	*t;
 	int			error = 0;

 	m->actual_length = 0;
 	m->status = -EINPROGRESS;

 	hw = spi_master_get_devdata(spi->master);

 	if (list_empty(&m->transfers) || !m->complete)
 		return -EINVAL;

 	list_for_each_entry(t, &m->transfers, transfer_list) {
 		if (t->len && !(t->rx_buf || t->tx_buf)) {
 			dev_err(&spi->dev, "invalid xfer, no buffer\n");
 			return -EINVAL;
 		}

 		if (t->len && t->rx_buf && t->tx_buf) {
 			dev_err(&spi->dev, "invalid xfer, full duplex\n");
 			return -EINVAL;
 		}

 		if (t->bits_per_word > 32) {
 			dev_err(&spi->dev, "invalid xfer width %d\n",
 				t->bits_per_word);
 			return -EINVAL;
 		}
 	}

 	spin_lock(&hw->lock);
 	if (hw->shutdown) {
 		error = -ESHUTDOWN;
 		goto error_unlock;
 	}
 	list_add_tail(&m->queue, &hw->msg_queue);
 	queue_work(hw->workqueue, &hw->work);
 error_unlock:
 	spin_unlock(&hw->lock);
 	return error;
 }

 static int ti_ssp_spi_probe(struct platform_device *pdev)
 {
 	const struct ti_ssp_spi_data *pdata;
 	struct ti_ssp_spi *hw;
 	struct spi_master *master;
 	struct device *dev = &pdev->dev;
 	int error = 0;

 	pdata = dev->platform_data;
 	if (!pdata) {
 		dev_err(dev, "platform data not found\n");
 		return -EINVAL;
 	}

 	master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
 	if (!master) {
 		dev_err(dev, "cannot allocate SPI master\n");
 		return -ENOMEM;
 	}

 	hw = spi_master_get_devdata(master);
 	platform_set_drvdata(pdev, hw);

 	hw->master = master;
 	hw->dev = dev;
 	hw->select = pdata->select;

 	spin_lock_init(&hw->lock);
 	init_completion(&hw->complete);
 	INIT_LIST_HEAD(&hw->msg_queue);
 	INIT_WORK(&hw->work, ti_ssp_spi_work);

 	hw->workqueue = create_singlethread_workqueue(dev_name(dev));
 	if (!hw->workqueue) {
 		error = -ENOMEM;
 		dev_err(dev, "work queue creation failed\n");
 		goto error_wq;
 	}

 	error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
 	if (error < 0) {
 		dev_err(dev, "io setup failed\n");
 		goto error_iosel;
 	}

 	master->bus_num		= pdev->id;
 	master->num_chipselect	= pdata->num_cs;
 	master->mode_bits	= MODE_BITS;
 	master->flags		= SPI_MASTER_HALF_DUPLEX;
 	master->setup		= ti_ssp_spi_setup;
 	master->transfer	= ti_ssp_spi_transfer;

 	error = spi_register_master(master);
 	if (error) {
 		dev_err(dev, "master registration failed\n");
 		goto error_reg;
 	}

 	return 0;

 error_reg:
 error_iosel:
 	destroy_workqueue(hw->workqueue);
 error_wq:
 	spi_master_put(master);
 	return error;
 }

 static int ti_ssp_spi_remove(struct platform_device *pdev)
 {
 	struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
 	int error;

 	hw->shutdown = 1;
 	while (!list_empty(&hw->msg_queue)) {
 		error = wait_for_completion_interruptible(&hw->complete);
 		if (error < 0) {
 			hw->shutdown = 0;
 			return error;
 		}
 	}
 	destroy_workqueue(hw->workqueue);
 	spi_unregister_master(hw->master);

 	return 0;
 }

 static struct platform_driver ti_ssp_spi_driver = {
 	.probe		= ti_ssp_spi_probe,
 	.remove		= ti_ssp_spi_remove,
 	.driver		= {
 		.name	= "ti-ssp-spi",
 		.owner	= THIS_MODULE,
 	},
 };
 module_platform_driver(ti_ssp_spi_driver);

 MODULE_DESCRIPTION("SSP SPI Master");
 MODULE_AUTHOR("Cyril Chemparathy");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:ti-ssp-spi");
	/*
	* Sequencer Serial Port (SSP) based SPI master driver
	*
	* Copyright (C) 2010 Texas Instruments Inc
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/kernel.h>
	#include <linux/err.h>
	#include <linux/completion.h>
	#include <linux/delay.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/spi/spi.h>
	#include <linux/mfd/ti_ssp.h>

	#define MODE_BITS (SPI_CPHA \| SPI_CPOL \| SPI_CS_HIGH)

	struct ti_ssp_spi {
	struct spi_master *master;
	struct device *dev;
	spinlock_t lock;
	struct list_head msg_queue;
	struct completion complete;
	bool shutdown;
	struct workqueue_struct *workqueue;
	struct work_struct work;
	u8 mode, bpw;
	int cs_active;
	u32 pc_en, pc_dis, pc_wr, pc_rd;
	void (*select)(int cs);
	};

	static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
	{
	u32 ret;

	ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
	return ret;
	}

	static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
	{
	ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
	}

	static int ti_ssp_spi_txrx(struct ti_ssp_spi hw, struct spi_message msg,
	struct spi_transfer *t)
	{
	int count;

	if (hw->bpw <= 8) {
	u8 *rx = t->rx_buf;
	const u8 *tx = t->tx_buf;

	for (count = 0; count < t->len; count += 1) {
	if (t->tx_buf)
	ti_ssp_spi_tx(hw, *tx++);
	if (t->rx_buf)
	*rx++ = ti_ssp_spi_rx(hw);
	}
	} else if (hw->bpw <= 16) {
	u16 *rx = t->rx_buf;
	const u16 *tx = t->tx_buf;

	for (count = 0; count < t->len; count += 2) {
	if (t->tx_buf)
	ti_ssp_spi_tx(hw, *tx++);
	if (t->rx_buf)
	*rx++ = ti_ssp_spi_rx(hw);
	}
	} else {
	u32 *rx = t->rx_buf;
	const u32 *tx = t->tx_buf;

	for (count = 0; count < t->len; count += 4) {
	if (t->tx_buf)
	ti_ssp_spi_tx(hw, *tx++);
	if (t->rx_buf)
	*rx++ = ti_ssp_spi_rx(hw);
	}
	}

	msg->actual_length += count; /* bytes transferred */

	dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
	t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
	hw->bpw, count, (count < t->len) ? " (under)" : "");

	return (count < t->len) ? -EIO : 0; /* left over data */
	}

	static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
	{
	cs_active = !!cs_active;
	if (cs_active == hw->cs_active)
	return;
	ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
	hw->cs_active = cs_active;
	}

	#define __SHIFT_OUT(bits) (SSP_OPCODE_SHIFT \| SSP_OUT_MODE \| \
	cs_en \| clk \| SSP_COUNT((bits) * 2 - 1))
	#define __SHIFT_IN(bits) (SSP_OPCODE_SHIFT \| SSP_IN_MODE \| \
	cs_en \| clk \| SSP_COUNT((bits) * 2 - 1))

	static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
	{
	int error, idx = 0;
	u32 seqram[16];
	u32 cs_en, cs_dis, clk;
	u32 topbits, botbits;

	mode &= MODE_BITS;
	if (mode == hw->mode && bpw == hw->bpw)
	return 0;

	cs_en = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
	cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW : SSP_CS_HIGH;
	clk = (mode & SPI_CPOL) ? SSP_CLK_HIGH : SSP_CLK_LOW;

	/* Construct instructions */

	/* Disable Chip Select */
	hw->pc_dis = idx;
	seqram[idx++] = SSP_OPCODE_DIRECT \| SSP_OUT_MODE \| cs_dis \| clk;
	seqram[idx++] = SSP_OPCODE_STOP \| SSP_OUT_MODE \| cs_dis \| clk;

	/* Enable Chip Select */
	hw->pc_en = idx;
	seqram[idx++] = SSP_OPCODE_DIRECT \| SSP_OUT_MODE \| cs_en \| clk;
	seqram[idx++] = SSP_OPCODE_STOP \| SSP_OUT_MODE \| cs_en \| clk;

	/* Reads and writes need to be split for bpw > 16 */
	topbits = (bpw > 16) ? 16 : bpw;
	botbits = bpw - topbits;

	/* Write */
	hw->pc_wr = idx;
	seqram[idx++] = __SHIFT_OUT(topbits) \| SSP_ADDR_REG;
	if (botbits)
	seqram[idx++] = __SHIFT_OUT(botbits) \| SSP_DATA_REG;
	seqram[idx++] = SSP_OPCODE_STOP \| SSP_OUT_MODE \| cs_en \| clk;

	/* Read */
	hw->pc_rd = idx;
	if (botbits)
	seqram[idx++] = __SHIFT_IN(botbits) \| SSP_ADDR_REG;
	seqram[idx++] = __SHIFT_IN(topbits) \| SSP_DATA_REG;
	seqram[idx++] = SSP_OPCODE_STOP \| SSP_OUT_MODE \| cs_en \| clk;

	error = ti_ssp_load(hw->dev, 0, seqram, idx);
	if (error < 0)
	return error;

	error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
	0 : SSP_EARLY_DIN));
	if (error < 0)
	return error;

	hw->bpw = bpw;
	hw->mode = mode;

	return error;
	}

	static void ti_ssp_spi_work(struct work_struct *work)
	{
	struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);

	spin_lock(&hw->lock);

	while (!list_empty(&hw->msg_queue)) {
	struct spi_message *m;
	struct spi_device *spi;
	struct spi_transfer *t = NULL;
	int status = 0;

	m = container_of(hw->msg_queue.next, struct spi_message,
	queue);

	list_del_init(&m->queue);

	spin_unlock(&hw->lock);

	spi = m->spi;

	if (hw->select)
	hw->select(spi->chip_select);

	list_for_each_entry(t, &m->transfers, transfer_list) {
	int bpw = spi->bits_per_word;
	int xfer_status;

	if (t->bits_per_word)
	bpw = t->bits_per_word;

	if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
	break;

	ti_ssp_spi_chip_select(hw, 1);

	xfer_status = ti_ssp_spi_txrx(hw, m, t);
	if (xfer_status < 0)
	status = xfer_status;

	if (t->delay_usecs)
	udelay(t->delay_usecs);

	if (t->cs_change)
	ti_ssp_spi_chip_select(hw, 0);
	}

	ti_ssp_spi_chip_select(hw, 0);
	m->status = status;
	m->complete(m->context);

	spin_lock(&hw->lock);
	}

	if (hw->shutdown)
	complete(&hw->complete);

	spin_unlock(&hw->lock);
	}

	static int ti_ssp_spi_setup(struct spi_device *spi)
	{
	if (spi->bits_per_word > 32)
	return -EINVAL;

	return 0;
	}

	static int ti_ssp_spi_transfer(struct spi_device spi, struct spi_message m)
	{
	struct ti_ssp_spi *hw;
	struct spi_transfer *t;
	int error = 0;

	m->actual_length = 0;
	m->status = -EINPROGRESS;

	hw = spi_master_get_devdata(spi->master);

	if (list_empty(&m->transfers) \|\| !m->complete)
	return -EINVAL;

	list_for_each_entry(t, &m->transfers, transfer_list) {
	if (t->len && !(t->rx_buf \|\| t->tx_buf)) {
	dev_err(&spi->dev, "invalid xfer, no buffer\n");
	return -EINVAL;
	}

	if (t->len && t->rx_buf && t->tx_buf) {
	dev_err(&spi->dev, "invalid xfer, full duplex\n");
	return -EINVAL;
	}

	if (t->bits_per_word > 32) {
	dev_err(&spi->dev, "invalid xfer width %d\n",
	t->bits_per_word);
	return -EINVAL;
	}
	}

	spin_lock(&hw->lock);
	if (hw->shutdown) {
	error = -ESHUTDOWN;
	goto error_unlock;
	}
	list_add_tail(&m->queue, &hw->msg_queue);
	queue_work(hw->workqueue, &hw->work);
	error_unlock:
	spin_unlock(&hw->lock);
	return error;
	}

	static int ti_ssp_spi_probe(struct platform_device *pdev)
	{
	const struct ti_ssp_spi_data *pdata;
	struct ti_ssp_spi *hw;
	struct spi_master *master;
	struct device *dev = &pdev->dev;
	int error = 0;

	pdata = dev->platform_data;
	if (!pdata) {
	dev_err(dev, "platform data not found\n");
	return -EINVAL;
	}

	master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
	if (!master) {
	dev_err(dev, "cannot allocate SPI master\n");
	return -ENOMEM;
	}

	hw = spi_master_get_devdata(master);
	platform_set_drvdata(pdev, hw);

	hw->master = master;
	hw->dev = dev;
	hw->select = pdata->select;

	spin_lock_init(&hw->lock);
	init_completion(&hw->complete);
	INIT_LIST_HEAD(&hw->msg_queue);
	INIT_WORK(&hw->work, ti_ssp_spi_work);

	hw->workqueue = create_singlethread_workqueue(dev_name(dev));
	if (!hw->workqueue) {
	error = -ENOMEM;
	dev_err(dev, "work queue creation failed\n");
	goto error_wq;
	}

	error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
	if (error < 0) {
	dev_err(dev, "io setup failed\n");
	goto error_iosel;
	}

	master->bus_num = pdev->id;
	master->num_chipselect = pdata->num_cs;
	master->mode_bits = MODE_BITS;
	master->flags = SPI_MASTER_HALF_DUPLEX;
	master->setup = ti_ssp_spi_setup;
	master->transfer = ti_ssp_spi_transfer;

	error = spi_register_master(master);
	if (error) {
	dev_err(dev, "master registration failed\n");
	goto error_reg;
	}

	return 0;

	error_reg:
	error_iosel:
	destroy_workqueue(hw->workqueue);
	error_wq:
	spi_master_put(master);
	return error;
	}

	static int ti_ssp_spi_remove(struct platform_device *pdev)
	{
	struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
	int error;

	hw->shutdown = 1;
	while (!list_empty(&hw->msg_queue)) {
	error = wait_for_completion_interruptible(&hw->complete);
	if (error < 0) {
	hw->shutdown = 0;
	return error;
	}
	}
	destroy_workqueue(hw->workqueue);
	spi_unregister_master(hw->master);

	return 0;
	}

	static struct platform_driver ti_ssp_spi_driver = {
	.probe = ti_ssp_spi_probe,
	.remove = ti_ssp_spi_remove,
	.driver = {
	.name = "ti-ssp-spi",
	.owner = THIS_MODULE,
	},
	};
	module_platform_driver(ti_ssp_spi_driver);

	MODULE_DESCRIPTION("SSP SPI Master");
	MODULE_AUTHOR("Cyril Chemparathy");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:ti-ssp-spi");