drivers/spi/mpc52xx_spi.c - kernel/msm-4.9 - Gitiles

 /*
  * MPC52xx SPI bus driver.
  *
  * Copyright (C) 2008 Secret Lab Technologies Ltd.
  *
  * This file is released under the GPLv2
  *
  * This is the driver for the MPC5200's dedicated SPI controller.
  *
  * Note: this driver does not support the MPC5200 PSC in SPI mode.  For
  * that driver see drivers/spi/mpc52xx_psc_spi.c
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/of_platform.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/spi/spi.h>
 #include <linux/io.h>
 #include <linux/of_gpio.h>
 #include <linux/slab.h>
 #include <asm/time.h>
 #include <asm/mpc52xx.h>

 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver");
 MODULE_LICENSE("GPL");

 /* Register offsets */
 #define SPI_CTRL1	0x00
 #define SPI_CTRL1_SPIE		(1 << 7)
 #define SPI_CTRL1_SPE		(1 << 6)
 #define SPI_CTRL1_MSTR		(1 << 4)
 #define SPI_CTRL1_CPOL		(1 << 3)
 #define SPI_CTRL1_CPHA		(1 << 2)
 #define SPI_CTRL1_SSOE		(1 << 1)
 #define SPI_CTRL1_LSBFE		(1 << 0)

 #define SPI_CTRL2	0x01
 #define SPI_BRR		0x04

 #define SPI_STATUS	0x05
 #define SPI_STATUS_SPIF		(1 << 7)
 #define SPI_STATUS_WCOL		(1 << 6)
 #define SPI_STATUS_MODF		(1 << 4)

 #define SPI_DATA	0x09
 #define SPI_PORTDATA	0x0d
 #define SPI_DATADIR	0x10

 /* FSM state return values */
 #define FSM_STOP	0	/* Nothing more for the state machine to */
 				/* do.  If something interesting happens */
 				/* then an IRQ will be received */
 #define FSM_POLL	1	/* need to poll for completion, an IRQ is */
 				/* not expected */
 #define FSM_CONTINUE	2	/* Keep iterating the state machine */

 /* Driver internal data */
 struct mpc52xx_spi {
 	struct spi_master *master;
 	void __iomem *regs;
 	int irq0;	/* MODF irq */
 	int irq1;	/* SPIF irq */
 	unsigned int ipb_freq;

 	/* Statistics; not used now, but will be reintroduced for debugfs */
 	int msg_count;
 	int wcol_count;
 	int wcol_ticks;
 	u32 wcol_tx_timestamp;
 	int modf_count;
 	int byte_count;

 	struct list_head queue;		/* queue of pending messages */
 	spinlock_t lock;
 	struct work_struct work;

 	/* Details of current transfer (length, and buffer pointers) */
 	struct spi_message *message;	/* current message */
 	struct spi_transfer *transfer;	/* current transfer */
 	int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data);
 	int len;
 	int timestamp;
 	u8 *rx_buf;
 	const u8 *tx_buf;
 	int cs_change;
 	int gpio_cs_count;
 	unsigned int *gpio_cs;
 };

 /*
  * CS control function
  */
 static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value)
 {
 	int cs;

 	if (ms->gpio_cs_count > 0) {
 		cs = ms->message->spi->chip_select;
 		gpio_set_value(ms->gpio_cs[cs], value ? 0 : 1);
 	} else
 		out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08);
 }

 /*
  * Start a new transfer.  This is called both by the idle state
  * for the first transfer in a message, and by the wait state when the
  * previous transfer in a message is complete.
  */
 static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms)
 {
 	ms->rx_buf = ms->transfer->rx_buf;
 	ms->tx_buf = ms->transfer->tx_buf;
 	ms->len = ms->transfer->len;

 	/* Activate the chip select */
 	if (ms->cs_change)
 		mpc52xx_spi_chipsel(ms, 1);
 	ms->cs_change = ms->transfer->cs_change;

 	/* Write out the first byte */
 	ms->wcol_tx_timestamp = get_tbl();
 	if (ms->tx_buf)
 		out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
 	else
 		out_8(ms->regs + SPI_DATA, 0);
 }

 /* Forward declaration of state handlers */
 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
 					 u8 status, u8 data);
 static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms,
 				     u8 status, u8 data);

 /*
  * IDLE state
  *
  * No transfers are in progress; if another transfer is pending then retrieve
  * it and kick it off.  Otherwise, stop processing the state machine
  */
 static int
 mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
 {
 	struct spi_device *spi;
 	int spr, sppr;
 	u8 ctrl1;

 	if (status && (irq != NO_IRQ))
 		dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
 			status);

 	/* Check if there is another transfer waiting. */
 	if (list_empty(&ms->queue))
 		return FSM_STOP;

 	/* get the head of the queue */
 	ms->message = list_first_entry(&ms->queue, struct spi_message, queue);
 	list_del_init(&ms->message->queue);

 	/* Setup the controller parameters */
 	ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
 	spi = ms->message->spi;
 	if (spi->mode & SPI_CPHA)
 		ctrl1 |= SPI_CTRL1_CPHA;
 	if (spi->mode & SPI_CPOL)
 		ctrl1 |= SPI_CTRL1_CPOL;
 	if (spi->mode & SPI_LSB_FIRST)
 		ctrl1 |= SPI_CTRL1_LSBFE;
 	out_8(ms->regs + SPI_CTRL1, ctrl1);

 	/* Setup the controller speed */
 	/* minimum divider is '2'.  Also, add '1' to force rounding the
 	 * divider up. */
 	sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1;
 	spr = 0;
 	if (sppr < 1)
 		sppr = 1;
 	while (((sppr - 1) & ~0x7) != 0) {
 		sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */
 		spr++;
 	}
 	sppr--;		/* sppr quantity in register is offset by 1 */
 	if (spr > 7) {
 		/* Don't overrun limits of SPI baudrate register */
 		spr = 7;
 		sppr = 7;
 	}
 	out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */

 	ms->cs_change = 1;
 	ms->transfer = container_of(ms->message->transfers.next,
 				    struct spi_transfer, transfer_list);

 	mpc52xx_spi_start_transfer(ms);
 	ms->state = mpc52xx_spi_fsmstate_transfer;

 	return FSM_CONTINUE;
 }

 /*
  * TRANSFER state
  *
  * In the middle of a transfer.  If the SPI core has completed processing
  * a byte, then read out the received data and write out the next byte
  * (unless this transfer is finished; in which case go on to the wait
  * state)
  */
 static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
 					 u8 status, u8 data)
 {
 	if (!status)
 		return ms->irq0 ? FSM_STOP : FSM_POLL;

 	if (status & SPI_STATUS_WCOL) {
 		/* The SPI controller is stoopid.  At slower speeds, it may
 		 * raise the SPIF flag before the state machine is actually
 		 * finished, which causes a collision (internal to the state
 		 * machine only).  The manual recommends inserting a delay
 		 * between receiving the interrupt and sending the next byte,
 		 * but it can also be worked around simply by retrying the
 		 * transfer which is what we do here. */
 		ms->wcol_count++;
 		ms->wcol_ticks += get_tbl() - ms->wcol_tx_timestamp;
 		ms->wcol_tx_timestamp = get_tbl();
 		data = 0;
 		if (ms->tx_buf)
 			data = *(ms->tx_buf - 1);
 		out_8(ms->regs + SPI_DATA, data); /* try again */
 		return FSM_CONTINUE;
 	} else if (status & SPI_STATUS_MODF) {
 		ms->modf_count++;
 		dev_err(&ms->master->dev, "mode fault\n");
 		mpc52xx_spi_chipsel(ms, 0);
 		ms->message->status = -EIO;
 		ms->message->complete(ms->message->context);
 		ms->state = mpc52xx_spi_fsmstate_idle;
 		return FSM_CONTINUE;
 	}

 	/* Read data out of the spi device */
 	ms->byte_count++;
 	if (ms->rx_buf)
 		*ms->rx_buf++ = data;

 	/* Is the transfer complete? */
 	ms->len--;
 	if (ms->len == 0) {
 		ms->timestamp = get_tbl();
 		ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec;
 		ms->state = mpc52xx_spi_fsmstate_wait;
 		return FSM_CONTINUE;
 	}

 	/* Write out the next byte */
 	ms->wcol_tx_timestamp = get_tbl();
 	if (ms->tx_buf)
 		out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
 	else
 		out_8(ms->regs + SPI_DATA, 0);

 	return FSM_CONTINUE;
 }

 /*
  * WAIT state
  *
  * A transfer has completed; need to wait for the delay period to complete
  * before starting the next transfer
  */
 static int
 mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
 {
 	if (status && irq)
 		dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
 			status);

 	if (((int)get_tbl()) - ms->timestamp < 0)
 		return FSM_POLL;

 	ms->message->actual_length += ms->transfer->len;

 	/* Check if there is another transfer in this message.  If there
 	 * aren't then deactivate CS, notify sender, and drop back to idle
 	 * to start the next message. */
 	if (ms->transfer->transfer_list.next == &ms->message->transfers) {
 		ms->msg_count++;
 		mpc52xx_spi_chipsel(ms, 0);
 		ms->message->status = 0;
 		ms->message->complete(ms->message->context);
 		ms->state = mpc52xx_spi_fsmstate_idle;
 		return FSM_CONTINUE;
 	}

 	/* There is another transfer; kick it off */

 	if (ms->cs_change)
 		mpc52xx_spi_chipsel(ms, 0);

 	ms->transfer = container_of(ms->transfer->transfer_list.next,
 				    struct spi_transfer, transfer_list);
 	mpc52xx_spi_start_transfer(ms);
 	ms->state = mpc52xx_spi_fsmstate_transfer;
 	return FSM_CONTINUE;
 }

 /**
  * mpc52xx_spi_fsm_process - Finite State Machine iteration function
  * @irq: irq number that triggered the FSM or 0 for polling
  * @ms: pointer to mpc52xx_spi driver data
  */
 static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms)
 {
 	int rc = FSM_CONTINUE;
 	u8 status, data;

 	while (rc == FSM_CONTINUE) {
 		/* Interrupt cleared by read of STATUS followed by
 		 * read of DATA registers */
 		status = in_8(ms->regs + SPI_STATUS);
 		data = in_8(ms->regs + SPI_DATA);
 		rc = ms->state(irq, ms, status, data);
 	}

 	if (rc == FSM_POLL)
 		schedule_work(&ms->work);
 }

 /**
  * mpc52xx_spi_irq - IRQ handler
  */
 static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms)
 {
 	struct mpc52xx_spi *ms = _ms;
 	spin_lock(&ms->lock);
 	mpc52xx_spi_fsm_process(irq, ms);
 	spin_unlock(&ms->lock);
 	return IRQ_HANDLED;
 }

 /**
  * mpc52xx_spi_wq - Workqueue function for polling the state machine
  */
 static void mpc52xx_spi_wq(struct work_struct *work)
 {
 	struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work);
 	unsigned long flags;

 	spin_lock_irqsave(&ms->lock, flags);
 	mpc52xx_spi_fsm_process(0, ms);
 	spin_unlock_irqrestore(&ms->lock, flags);
 }

 /*
  * spi_master ops
  */

 static int mpc52xx_spi_setup(struct spi_device *spi)
 {
 	if (spi->bits_per_word % 8)
 		return -EINVAL;

 	if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST))
 		return -EINVAL;

 	if (spi->chip_select >= spi->master->num_chipselect)
 		return -EINVAL;

 	return 0;
 }

 static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m)
 {
 	struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master);
 	unsigned long flags;

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

 	spin_lock_irqsave(&ms->lock, flags);
 	list_add_tail(&m->queue, &ms->queue);
 	spin_unlock_irqrestore(&ms->lock, flags);
 	schedule_work(&ms->work);

 	return 0;
 }

 /*
  * OF Platform Bus Binding
  */
 static int __devinit mpc52xx_spi_probe(struct platform_device *op)
 {
 	struct spi_master *master;
 	struct mpc52xx_spi *ms;
 	void __iomem *regs;
 	u8 ctrl1;
 	int rc, i = 0;
 	int gpio_cs;

 	/* MMIO registers */
 	dev_dbg(&op->dev, "probing mpc5200 SPI device\n");
 	regs = of_iomap(op->dev.of_node, 0);
 	if (!regs)
 		return -ENODEV;

 	/* initialize the device */
 	ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
 	out_8(regs + SPI_CTRL1, ctrl1);
 	out_8(regs + SPI_CTRL2, 0x0);
 	out_8(regs + SPI_DATADIR, 0xe);	/* Set output pins */
 	out_8(regs + SPI_PORTDATA, 0x8);	/* Deassert /SS signal */

 	/* Clear the status register and re-read it to check for a MODF
 	 * failure.  This driver cannot currently handle multiple masters
 	 * on the SPI bus.  This fault will also occur if the SPI signals
 	 * are not connected to any pins (port_config setting) */
 	in_8(regs + SPI_STATUS);
 	out_8(regs + SPI_CTRL1, ctrl1);

 	in_8(regs + SPI_DATA);
 	if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) {
 		dev_err(&op->dev, "mode fault; is port_config correct?\n");
 		rc = -EIO;
 		goto err_init;
 	}

 	dev_dbg(&op->dev, "allocating spi_master struct\n");
 	master = spi_alloc_master(&op->dev, sizeof *ms);
 	if (!master) {
 		rc = -ENOMEM;
 		goto err_alloc;
 	}

 	master->bus_num = -1;
 	master->setup = mpc52xx_spi_setup;
 	master->transfer = mpc52xx_spi_transfer;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;
 	master->dev.of_node = op->dev.of_node;

 	dev_set_drvdata(&op->dev, master);

 	ms = spi_master_get_devdata(master);
 	ms->master = master;
 	ms->regs = regs;
 	ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0);
 	ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1);
 	ms->state = mpc52xx_spi_fsmstate_idle;
 	ms->ipb_freq = mpc5xxx_get_bus_frequency(op->dev.of_node);
 	ms->gpio_cs_count = of_gpio_count(op->dev.of_node);
 	if (ms->gpio_cs_count > 0) {
 		master->num_chipselect = ms->gpio_cs_count;
 		ms->gpio_cs = kmalloc(ms->gpio_cs_count * sizeof(unsigned int),
 				GFP_KERNEL);
 		if (!ms->gpio_cs) {
 			rc = -ENOMEM;
 			goto err_alloc;
 		}

 		for (i = 0; i < ms->gpio_cs_count; i++) {
 			gpio_cs = of_get_gpio(op->dev.of_node, i);
 			if (gpio_cs < 0) {
 				dev_err(&op->dev,
 					"could not parse the gpio field "
 					"in oftree\n");
 				rc = -ENODEV;
 				goto err_gpio;
 			}

 			rc = gpio_request(gpio_cs, dev_name(&op->dev));
 			if (rc) {
 				dev_err(&op->dev,
 					"can't request spi cs gpio #%d "
 					"on gpio line %d\n", i, gpio_cs);
 				goto err_gpio;
 			}

 			gpio_direction_output(gpio_cs, 1);
 			ms->gpio_cs[i] = gpio_cs;
 		}
 	} else {
 		master->num_chipselect = 1;
 	}

 	spin_lock_init(&ms->lock);
 	INIT_LIST_HEAD(&ms->queue);
 	INIT_WORK(&ms->work, mpc52xx_spi_wq);

 	/* Decide if interrupts can be used */
 	if (ms->irq0 && ms->irq1) {
 		rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0,
 				  "mpc5200-spi-modf", ms);
 		rc |= request_irq(ms->irq1, mpc52xx_spi_irq, 0,
 				  "mpc5200-spi-spif", ms);
 		if (rc) {
 			free_irq(ms->irq0, ms);
 			free_irq(ms->irq1, ms);
 			ms->irq0 = ms->irq1 = 0;
 		}
 	} else {
 		/* operate in polled mode */
 		ms->irq0 = ms->irq1 = 0;
 	}

 	if (!ms->irq0)
 		dev_info(&op->dev, "using polled mode\n");

 	dev_dbg(&op->dev, "registering spi_master struct\n");
 	rc = spi_register_master(master);
 	if (rc)
 		goto err_register;

 	dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n");

 	return rc;

  err_register:
 	dev_err(&ms->master->dev, "initialization failed\n");
 	spi_master_put(master);
  err_gpio:
 	while (i-- > 0)
 		gpio_free(ms->gpio_cs[i]);

 	kfree(ms->gpio_cs);
  err_alloc:
  err_init:
 	iounmap(regs);
 	return rc;
 }

 static int __devexit mpc52xx_spi_remove(struct platform_device *op)
 {
 	struct spi_master *master = dev_get_drvdata(&op->dev);
 	struct mpc52xx_spi *ms = spi_master_get_devdata(master);
 	int i;

 	free_irq(ms->irq0, ms);
 	free_irq(ms->irq1, ms);

 	for (i = 0; i < ms->gpio_cs_count; i++)
 		gpio_free(ms->gpio_cs[i]);

 	kfree(ms->gpio_cs);
 	spi_unregister_master(master);
 	spi_master_put(master);
 	iounmap(ms->regs);

 	return 0;
 }

 static const struct of_device_id mpc52xx_spi_match[] __devinitconst = {
 	{ .compatible = "fsl,mpc5200-spi", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, mpc52xx_spi_match);

 static struct platform_driver mpc52xx_spi_of_driver = {
 	.driver = {
 		.name = "mpc52xx-spi",
 		.owner = THIS_MODULE,
 		.of_match_table = mpc52xx_spi_match,
 	},
 	.probe = mpc52xx_spi_probe,
 	.remove = __devexit_p(mpc52xx_spi_remove),
 };

 static int __init mpc52xx_spi_init(void)
 {
 	return platform_driver_register(&mpc52xx_spi_of_driver);
 }
 module_init(mpc52xx_spi_init);

 static void __exit mpc52xx_spi_exit(void)
 {
 	platform_driver_unregister(&mpc52xx_spi_of_driver);
 }
 module_exit(mpc52xx_spi_exit);
	/*
	* MPC52xx SPI bus driver.
	*
	* Copyright (C) 2008 Secret Lab Technologies Ltd.
	*
	* This file is released under the GPLv2
	*
	* This is the driver for the MPC5200's dedicated SPI controller.
	*
	* Note: this driver does not support the MPC5200 PSC in SPI mode. For
	* that driver see drivers/spi/mpc52xx_psc_spi.c
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/errno.h>
	#include <linux/of_platform.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/spi/spi.h>
	#include <linux/io.h>
	#include <linux/of_gpio.h>
	#include <linux/slab.h>
	#include <asm/time.h>
	#include <asm/mpc52xx.h>

	MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
	MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver");
	MODULE_LICENSE("GPL");

	/* Register offsets */
	#define SPI_CTRL1 0x00
	#define SPI_CTRL1_SPIE (1 << 7)
	#define SPI_CTRL1_SPE (1 << 6)
	#define SPI_CTRL1_MSTR (1 << 4)
	#define SPI_CTRL1_CPOL (1 << 3)
	#define SPI_CTRL1_CPHA (1 << 2)
	#define SPI_CTRL1_SSOE (1 << 1)
	#define SPI_CTRL1_LSBFE (1 << 0)

	#define SPI_CTRL2 0x01
	#define SPI_BRR 0x04

	#define SPI_STATUS 0x05
	#define SPI_STATUS_SPIF (1 << 7)
	#define SPI_STATUS_WCOL (1 << 6)
	#define SPI_STATUS_MODF (1 << 4)

	#define SPI_DATA 0x09
	#define SPI_PORTDATA 0x0d
	#define SPI_DATADIR 0x10

	/* FSM state return values */
	#define FSM_STOP 0 /* Nothing more for the state machine to */
	/* do. If something interesting happens */
	/* then an IRQ will be received */
	#define FSM_POLL 1 /* need to poll for completion, an IRQ is */
	/* not expected */
	#define FSM_CONTINUE 2 /* Keep iterating the state machine */

	/* Driver internal data */
	struct mpc52xx_spi {
	struct spi_master *master;
	void __iomem *regs;
	int irq0; /* MODF irq */
	int irq1; /* SPIF irq */
	unsigned int ipb_freq;

	/* Statistics; not used now, but will be reintroduced for debugfs */
	int msg_count;
	int wcol_count;
	int wcol_ticks;
	u32 wcol_tx_timestamp;
	int modf_count;
	int byte_count;

	struct list_head queue; /* queue of pending messages */
	spinlock_t lock;
	struct work_struct work;

	/* Details of current transfer (length, and buffer pointers) */
	struct spi_message message; / current message */
	struct spi_transfer transfer; / current transfer */
	int (state)(int irq, struct mpc52xx_spi ms, u8 status, u8 data);
	int len;
	int timestamp;
	u8 *rx_buf;
	const u8 *tx_buf;
	int cs_change;
	int gpio_cs_count;
	unsigned int *gpio_cs;
	};

	/*
	* CS control function
	*/
	static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value)
	{
	int cs;

	if (ms->gpio_cs_count > 0) {
	cs = ms->message->spi->chip_select;
	gpio_set_value(ms->gpio_cs[cs], value ? 0 : 1);
	} else
	out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08);
	}

	/*
	* Start a new transfer. This is called both by the idle state
	* for the first transfer in a message, and by the wait state when the
	* previous transfer in a message is complete.
	*/
	static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms)
	{
	ms->rx_buf = ms->transfer->rx_buf;
	ms->tx_buf = ms->transfer->tx_buf;
	ms->len = ms->transfer->len;

	/* Activate the chip select */
	if (ms->cs_change)
	mpc52xx_spi_chipsel(ms, 1);
	ms->cs_change = ms->transfer->cs_change;

	/* Write out the first byte */
	ms->wcol_tx_timestamp = get_tbl();
	if (ms->tx_buf)
	out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
	else
	out_8(ms->regs + SPI_DATA, 0);
	}

	/* Forward declaration of state handlers */
	static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
	u8 status, u8 data);
	static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms,
	u8 status, u8 data);

	/*
	* IDLE state
	*
	* No transfers are in progress; if another transfer is pending then retrieve
	* it and kick it off. Otherwise, stop processing the state machine
	*/
	static int
	mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
	{
	struct spi_device *spi;
	int spr, sppr;
	u8 ctrl1;

	if (status && (irq != NO_IRQ))
	dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
	status);

	/* Check if there is another transfer waiting. */
	if (list_empty(&ms->queue))
	return FSM_STOP;

	/* get the head of the queue */
	ms->message = list_first_entry(&ms->queue, struct spi_message, queue);
	list_del_init(&ms->message->queue);

	/* Setup the controller parameters */
	ctrl1 = SPI_CTRL1_SPIE \| SPI_CTRL1_SPE \| SPI_CTRL1_MSTR;
	spi = ms->message->spi;
	if (spi->mode & SPI_CPHA)
	ctrl1 \|= SPI_CTRL1_CPHA;
	if (spi->mode & SPI_CPOL)
	ctrl1 \|= SPI_CTRL1_CPOL;
	if (spi->mode & SPI_LSB_FIRST)
	ctrl1 \|= SPI_CTRL1_LSBFE;
	out_8(ms->regs + SPI_CTRL1, ctrl1);

	/* Setup the controller speed */
	/* minimum divider is '2'. Also, add '1' to force rounding the
	* divider up. */
	sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1;
	spr = 0;
	if (sppr < 1)
	sppr = 1;
	while (((sppr - 1) & ~0x7) != 0) {
	sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */
	spr++;
	}
	sppr--; /* sppr quantity in register is offset by 1 */
	if (spr > 7) {
	/* Don't overrun limits of SPI baudrate register */
	spr = 7;
	sppr = 7;
	}
	out_8(ms->regs + SPI_BRR, sppr << 4 \| spr); /* Set speed */

	ms->cs_change = 1;
	ms->transfer = container_of(ms->message->transfers.next,
	struct spi_transfer, transfer_list);

	mpc52xx_spi_start_transfer(ms);
	ms->state = mpc52xx_spi_fsmstate_transfer;

	return FSM_CONTINUE;
	}

	/*
	* TRANSFER state
	*
	* In the middle of a transfer. If the SPI core has completed processing
	* a byte, then read out the received data and write out the next byte
	* (unless this transfer is finished; in which case go on to the wait
	* state)
	*/
	static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
	u8 status, u8 data)
	{
	if (!status)
	return ms->irq0 ? FSM_STOP : FSM_POLL;

	if (status & SPI_STATUS_WCOL) {
	/* The SPI controller is stoopid. At slower speeds, it may
	* raise the SPIF flag before the state machine is actually
	* finished, which causes a collision (internal to the state
	* machine only). The manual recommends inserting a delay
	* between receiving the interrupt and sending the next byte,
	* but it can also be worked around simply by retrying the
	* transfer which is what we do here. */
	ms->wcol_count++;
	ms->wcol_ticks += get_tbl() - ms->wcol_tx_timestamp;
	ms->wcol_tx_timestamp = get_tbl();
	data = 0;
	if (ms->tx_buf)
	data = *(ms->tx_buf - 1);
	out_8(ms->regs + SPI_DATA, data); /* try again */
	return FSM_CONTINUE;
	} else if (status & SPI_STATUS_MODF) {
	ms->modf_count++;
	dev_err(&ms->master->dev, "mode fault\n");
	mpc52xx_spi_chipsel(ms, 0);
	ms->message->status = -EIO;
	ms->message->complete(ms->message->context);
	ms->state = mpc52xx_spi_fsmstate_idle;
	return FSM_CONTINUE;
	}

	/* Read data out of the spi device */
	ms->byte_count++;
	if (ms->rx_buf)
	*ms->rx_buf++ = data;

	/* Is the transfer complete? */
	ms->len--;
	if (ms->len == 0) {
	ms->timestamp = get_tbl();
	ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec;
	ms->state = mpc52xx_spi_fsmstate_wait;
	return FSM_CONTINUE;
	}

	/* Write out the next byte */
	ms->wcol_tx_timestamp = get_tbl();
	if (ms->tx_buf)
	out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
	else
	out_8(ms->regs + SPI_DATA, 0);

	return FSM_CONTINUE;
	}

	/*
	* WAIT state
	*
	* A transfer has completed; need to wait for the delay period to complete
	* before starting the next transfer
	*/
	static int
	mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
	{
	if (status && irq)
	dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
	status);

	if (((int)get_tbl()) - ms->timestamp < 0)
	return FSM_POLL;

	ms->message->actual_length += ms->transfer->len;

	/* Check if there is another transfer in this message. If there
	* aren't then deactivate CS, notify sender, and drop back to idle
	* to start the next message. */
	if (ms->transfer->transfer_list.next == &ms->message->transfers) {
	ms->msg_count++;
	mpc52xx_spi_chipsel(ms, 0);
	ms->message->status = 0;
	ms->message->complete(ms->message->context);
	ms->state = mpc52xx_spi_fsmstate_idle;
	return FSM_CONTINUE;
	}

	/* There is another transfer; kick it off */

	if (ms->cs_change)
	mpc52xx_spi_chipsel(ms, 0);

	ms->transfer = container_of(ms->transfer->transfer_list.next,
	struct spi_transfer, transfer_list);
	mpc52xx_spi_start_transfer(ms);
	ms->state = mpc52xx_spi_fsmstate_transfer;
	return FSM_CONTINUE;
	}

	/**
	* mpc52xx_spi_fsm_process - Finite State Machine iteration function
	* @irq: irq number that triggered the FSM or 0 for polling
	* @ms: pointer to mpc52xx_spi driver data
	*/
	static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms)
	{
	int rc = FSM_CONTINUE;
	u8 status, data;

	while (rc == FSM_CONTINUE) {
	/* Interrupt cleared by read of STATUS followed by
	* read of DATA registers */
	status = in_8(ms->regs + SPI_STATUS);
	data = in_8(ms->regs + SPI_DATA);
	rc = ms->state(irq, ms, status, data);
	}

	if (rc == FSM_POLL)
	schedule_work(&ms->work);
	}

	/**
	* mpc52xx_spi_irq - IRQ handler
	*/
	static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms)
	{
	struct mpc52xx_spi *ms = _ms;
	spin_lock(&ms->lock);
	mpc52xx_spi_fsm_process(irq, ms);
	spin_unlock(&ms->lock);
	return IRQ_HANDLED;
	}

	/**
	* mpc52xx_spi_wq - Workqueue function for polling the state machine
	*/
	static void mpc52xx_spi_wq(struct work_struct *work)
	{
	struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work);
	unsigned long flags;

	spin_lock_irqsave(&ms->lock, flags);
	mpc52xx_spi_fsm_process(0, ms);
	spin_unlock_irqrestore(&ms->lock, flags);
	}

	/*
	* spi_master ops
	*/

	static int mpc52xx_spi_setup(struct spi_device *spi)
	{
	if (spi->bits_per_word % 8)
	return -EINVAL;

	if (spi->mode & ~(SPI_CPOL \| SPI_CPHA \| SPI_LSB_FIRST))
	return -EINVAL;

	if (spi->chip_select >= spi->master->num_chipselect)
	return -EINVAL;

	return 0;
	}

	static int mpc52xx_spi_transfer(struct spi_device spi, struct spi_message m)
	{
	struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master);
	unsigned long flags;

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

	spin_lock_irqsave(&ms->lock, flags);
	list_add_tail(&m->queue, &ms->queue);
	spin_unlock_irqrestore(&ms->lock, flags);
	schedule_work(&ms->work);

	return 0;
	}

	/*
	* OF Platform Bus Binding
	*/
	static int __devinit mpc52xx_spi_probe(struct platform_device *op)
	{
	struct spi_master *master;
	struct mpc52xx_spi *ms;
	void __iomem *regs;
	u8 ctrl1;
	int rc, i = 0;
	int gpio_cs;

	/* MMIO registers */
	dev_dbg(&op->dev, "probing mpc5200 SPI device\n");
	regs = of_iomap(op->dev.of_node, 0);
	if (!regs)
	return -ENODEV;

	/* initialize the device */
	ctrl1 = SPI_CTRL1_SPIE \| SPI_CTRL1_SPE \| SPI_CTRL1_MSTR;
	out_8(regs + SPI_CTRL1, ctrl1);
	out_8(regs + SPI_CTRL2, 0x0);
	out_8(regs + SPI_DATADIR, 0xe); /* Set output pins */
	out_8(regs + SPI_PORTDATA, 0x8); /* Deassert /SS signal */

	/* Clear the status register and re-read it to check for a MODF
	* failure. This driver cannot currently handle multiple masters
	* on the SPI bus. This fault will also occur if the SPI signals
	* are not connected to any pins (port_config setting) */
	in_8(regs + SPI_STATUS);
	out_8(regs + SPI_CTRL1, ctrl1);

	in_8(regs + SPI_DATA);
	if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) {
	dev_err(&op->dev, "mode fault; is port_config correct?\n");
	rc = -EIO;
	goto err_init;
	}

	dev_dbg(&op->dev, "allocating spi_master struct\n");
	master = spi_alloc_master(&op->dev, sizeof *ms);
	if (!master) {
	rc = -ENOMEM;
	goto err_alloc;
	}

	master->bus_num = -1;
	master->setup = mpc52xx_spi_setup;
	master->transfer = mpc52xx_spi_transfer;
	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_LSB_FIRST;
	master->dev.of_node = op->dev.of_node;

	dev_set_drvdata(&op->dev, master);

	ms = spi_master_get_devdata(master);
	ms->master = master;
	ms->regs = regs;
	ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0);
	ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1);
	ms->state = mpc52xx_spi_fsmstate_idle;
	ms->ipb_freq = mpc5xxx_get_bus_frequency(op->dev.of_node);
	ms->gpio_cs_count = of_gpio_count(op->dev.of_node);
	if (ms->gpio_cs_count > 0) {
	master->num_chipselect = ms->gpio_cs_count;
	ms->gpio_cs = kmalloc(ms->gpio_cs_count * sizeof(unsigned int),
	GFP_KERNEL);
	if (!ms->gpio_cs) {
	rc = -ENOMEM;
	goto err_alloc;
	}

	for (i = 0; i < ms->gpio_cs_count; i++) {
	gpio_cs = of_get_gpio(op->dev.of_node, i);
	if (gpio_cs < 0) {
	dev_err(&op->dev,
	"could not parse the gpio field "
	"in oftree\n");
	rc = -ENODEV;
	goto err_gpio;
	}

	rc = gpio_request(gpio_cs, dev_name(&op->dev));
	if (rc) {
	dev_err(&op->dev,
	"can't request spi cs gpio #%d "
	"on gpio line %d\n", i, gpio_cs);
	goto err_gpio;
	}

	gpio_direction_output(gpio_cs, 1);
	ms->gpio_cs[i] = gpio_cs;
	}
	} else {
	master->num_chipselect = 1;
	}

	spin_lock_init(&ms->lock);
	INIT_LIST_HEAD(&ms->queue);
	INIT_WORK(&ms->work, mpc52xx_spi_wq);

	/* Decide if interrupts can be used */
	if (ms->irq0 && ms->irq1) {
	rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0,
	"mpc5200-spi-modf", ms);
	rc \|= request_irq(ms->irq1, mpc52xx_spi_irq, 0,
	"mpc5200-spi-spif", ms);
	if (rc) {
	free_irq(ms->irq0, ms);
	free_irq(ms->irq1, ms);
	ms->irq0 = ms->irq1 = 0;
	}
	} else {
	/* operate in polled mode */
	ms->irq0 = ms->irq1 = 0;
	}

	if (!ms->irq0)
	dev_info(&op->dev, "using polled mode\n");

	dev_dbg(&op->dev, "registering spi_master struct\n");
	rc = spi_register_master(master);
	if (rc)
	goto err_register;

	dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n");

	return rc;

	err_register:
	dev_err(&ms->master->dev, "initialization failed\n");
	spi_master_put(master);
	err_gpio:
	while (i-- > 0)
	gpio_free(ms->gpio_cs[i]);

	kfree(ms->gpio_cs);
	err_alloc:
	err_init:
	iounmap(regs);
	return rc;
	}

	static int __devexit mpc52xx_spi_remove(struct platform_device *op)
	{
	struct spi_master *master = dev_get_drvdata(&op->dev);
	struct mpc52xx_spi *ms = spi_master_get_devdata(master);
	int i;

	free_irq(ms->irq0, ms);
	free_irq(ms->irq1, ms);

	for (i = 0; i < ms->gpio_cs_count; i++)
	gpio_free(ms->gpio_cs[i]);

	kfree(ms->gpio_cs);
	spi_unregister_master(master);
	spi_master_put(master);
	iounmap(ms->regs);

	return 0;
	}

	static const struct of_device_id mpc52xx_spi_match[] __devinitconst = {
	{ .compatible = "fsl,mpc5200-spi", },
	{}
	};
	MODULE_DEVICE_TABLE(of, mpc52xx_spi_match);

	static struct platform_driver mpc52xx_spi_of_driver = {
	.driver = {
	.name = "mpc52xx-spi",
	.owner = THIS_MODULE,
	.of_match_table = mpc52xx_spi_match,
	},
	.probe = mpc52xx_spi_probe,
	.remove = __devexit_p(mpc52xx_spi_remove),
	};

	static int __init mpc52xx_spi_init(void)
	{
	return platform_driver_register(&mpc52xx_spi_of_driver);
	}
	module_init(mpc52xx_spi_init);

	static void __exit mpc52xx_spi_exit(void)
	{
	platform_driver_unregister(&mpc52xx_spi_of_driver);
	}
	module_exit(mpc52xx_spi_exit);