/*
 * Freescale STMP378X SPI master driver
 *
 * Author: dmitry pervushin <dimka@embeddedalley.com>
 *
 * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
 */

/*
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>

#include <mach/platform.h>
#include <mach/stmp3xxx.h>
#include <mach/dma.h>
#include <mach/regs-ssp.h>
#include <mach/regs-apbh.h>


/* 0 means DMA mode(recommended, default), !0 - PIO mode */
static int pio;
static int clock;

/* default timeout for busy waits is 2 seconds */
#define STMP_SPI_TIMEOUT	(2 * HZ)

struct stmp_spi {
	int		id;

	void *  __iomem regs;	/* vaddr of the control registers */

	int		irq, err_irq;
	u32		dma;
	struct stmp3xxx_dma_descriptor d;

	u32		speed_khz;
	u32		saved_timings;
	u32		divider;

	struct clk	*clk;
	struct device	*master_dev;

	struct work_struct work;
	struct workqueue_struct *workqueue;

	/* lock protects queue access */
	spinlock_t lock;
	struct list_head queue;

	struct completion done;
};

#define busy_wait(cond)							\
	({								\
	unsigned long end_jiffies = jiffies + STMP_SPI_TIMEOUT;		\
	bool succeeded = false;						\
	do {								\
		if (cond) {						\
			succeeded = true;				\
			break;						\
		}							\
		cpu_relax();						\
	} while (time_before(end_jiffies, jiffies));			\
	succeeded;							\
	})

/**
 * stmp_spi_init_hw
 * Initialize the SSP port
 */
static int stmp_spi_init_hw(struct stmp_spi *ss)
{
	int err = 0;
	void *pins = ss->master_dev->platform_data;

	err = stmp3xxx_request_pin_group(pins, dev_name(ss->master_dev));
	if (err)
		goto out;

	ss->clk = clk_get(NULL, "ssp");
	if (IS_ERR(ss->clk)) {
		err = PTR_ERR(ss->clk);
		goto out_free_pins;
	}
	clk_enable(ss->clk);

	stmp3xxx_reset_block(ss->regs, false);
	stmp3xxx_dma_reset_channel(ss->dma);

	return 0;

out_free_pins:
	stmp3xxx_release_pin_group(pins, dev_name(ss->master_dev));
out:
	return err;
}

static void stmp_spi_release_hw(struct stmp_spi *ss)
{
	void *pins = ss->master_dev->platform_data;

	if (ss->clk && !IS_ERR(ss->clk)) {
		clk_disable(ss->clk);
		clk_put(ss->clk);
	}
	stmp3xxx_release_pin_group(pins, dev_name(ss->master_dev));
}

static int stmp_spi_setup_transfer(struct spi_device *spi,
		struct spi_transfer *t)
{
	u8 bits_per_word;
	u32 hz;
	struct stmp_spi *ss = spi_master_get_devdata(spi->master);
	u16 rate;

	bits_per_word = spi->bits_per_word;
	if (t && t->bits_per_word)
		bits_per_word = t->bits_per_word;

	/*
	 * Calculate speed:
	 *	- by default, use maximum speed from ssp clk
	 *	- if device overrides it, use it
	 *	- if transfer specifies other speed, use transfer's one
	 */
	hz = 1000 * ss->speed_khz / ss->divider;
	if (spi->max_speed_hz)
		hz = min(hz, spi->max_speed_hz);
	if (t && t->speed_hz)
		hz = min(hz, t->speed_hz);

	if (hz == 0) {
		dev_err(&spi->dev, "Cannot continue with zero clock\n");
		return -EINVAL;
	}

	if (bits_per_word != 8) {
		dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
			__func__, bits_per_word);
		return -EINVAL;
	}

	dev_dbg(&spi->dev, "Requested clk rate = %uHz, max = %uHz/%d = %uHz\n",
		hz, ss->speed_khz, ss->divider,
		ss->speed_khz * 1000 / ss->divider);

	if (ss->speed_khz * 1000 / ss->divider < hz) {
		dev_err(&spi->dev, "%s, unsupported clock rate %uHz\n",
			__func__, hz);
		return -EINVAL;
	}

	rate = 1000 * ss->speed_khz/ss->divider/hz;

	writel(BF(ss->divider, SSP_TIMING_CLOCK_DIVIDE)		|
	       BF(rate - 1, SSP_TIMING_CLOCK_RATE),
	       HW_SSP_TIMING + ss->regs);

	writel(BF(1 /* mode SPI */, SSP_CTRL1_SSP_MODE)		|
	       BF(4 /* 8 bits   */, SSP_CTRL1_WORD_LENGTH)	|
	       ((spi->mode & SPI_CPOL) ? BM_SSP_CTRL1_POLARITY : 0) |
	       ((spi->mode & SPI_CPHA) ? BM_SSP_CTRL1_PHASE : 0) |
	       (pio ? 0 : BM_SSP_CTRL1_DMA_ENABLE),
	       ss->regs + HW_SSP_CTRL1);

	return 0;
}

static int stmp_spi_setup(struct spi_device *spi)
{
	/* spi_setup() does basic checks,
	 * stmp_spi_setup_transfer() does more later
	 */
	if (spi->bits_per_word != 8) {
		dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
			__func__, spi->bits_per_word);
		return -EINVAL;
	}
	return 0;
}

static inline u32 stmp_spi_cs(unsigned cs)
{
	return  ((cs & 1) ? BM_SSP_CTRL0_WAIT_FOR_CMD : 0) |
		((cs & 2) ? BM_SSP_CTRL0_WAIT_FOR_IRQ : 0);
}

static int stmp_spi_txrx_dma(struct stmp_spi *ss, int cs,
		unsigned char *buf, dma_addr_t dma_buf, int len,
		int first, int last, bool write)
{
	u32 c0 = 0;
	dma_addr_t spi_buf_dma = dma_buf;
	int status = 0;
	enum dma_data_direction dir = write ? DMA_TO_DEVICE : DMA_FROM_DEVICE;

	c0 |= (first ? BM_SSP_CTRL0_LOCK_CS : 0);
	c0 |= (last ? BM_SSP_CTRL0_IGNORE_CRC : 0);
	c0 |= (write ? 0 : BM_SSP_CTRL0_READ);
	c0 |= BM_SSP_CTRL0_DATA_XFER;

	c0 |= stmp_spi_cs(cs);

	c0 |= BF(len, SSP_CTRL0_XFER_COUNT);

	if (!dma_buf)
		spi_buf_dma = dma_map_single(ss->master_dev, buf, len, dir);

	ss->d.command->cmd =
		BF(len, APBH_CHn_CMD_XFER_COUNT)	|
		BF(1, APBH_CHn_CMD_CMDWORDS)		|
		BM_APBH_CHn_CMD_WAIT4ENDCMD		|
		BM_APBH_CHn_CMD_IRQONCMPLT		|
		BF(write ? BV_APBH_CHn_CMD_COMMAND__DMA_READ :
			   BV_APBH_CHn_CMD_COMMAND__DMA_WRITE,
		   APBH_CHn_CMD_COMMAND);
	ss->d.command->pio_words[0] = c0;
	ss->d.command->buf_ptr = spi_buf_dma;

	stmp3xxx_dma_reset_channel(ss->dma);
	stmp3xxx_dma_clear_interrupt(ss->dma);
	stmp3xxx_dma_enable_interrupt(ss->dma);
	init_completion(&ss->done);
	stmp3xxx_dma_go(ss->dma, &ss->d, 1);
	wait_for_completion(&ss->done);

	if (!busy_wait(readl(ss->regs + HW_SSP_CTRL0) & BM_SSP_CTRL0_RUN))
		status = ETIMEDOUT;

	if (!dma_buf)
		dma_unmap_single(ss->master_dev, spi_buf_dma, len, dir);

	return status;
}

static inline void stmp_spi_enable(struct stmp_spi *ss)
{
	stmp3xxx_setl(BM_SSP_CTRL0_LOCK_CS, ss->regs + HW_SSP_CTRL0);
	stmp3xxx_clearl(BM_SSP_CTRL0_IGNORE_CRC, ss->regs + HW_SSP_CTRL0);
}

static inline void stmp_spi_disable(struct stmp_spi *ss)
{
	stmp3xxx_clearl(BM_SSP_CTRL0_LOCK_CS, ss->regs + HW_SSP_CTRL0);
	stmp3xxx_setl(BM_SSP_CTRL0_IGNORE_CRC, ss->regs + HW_SSP_CTRL0);
}

static int stmp_spi_txrx_pio(struct stmp_spi *ss, int cs,
		unsigned char *buf, int len,
		bool first, bool last, bool write)
{
	if (first)
		stmp_spi_enable(ss);

	stmp3xxx_setl(stmp_spi_cs(cs), ss->regs + HW_SSP_CTRL0);

	while (len--) {
		if (last && len <= 0)
			stmp_spi_disable(ss);

		stmp3xxx_clearl(BM_SSP_CTRL0_XFER_COUNT,
				ss->regs + HW_SSP_CTRL0);
		stmp3xxx_setl(1, ss->regs + HW_SSP_CTRL0);

		if (write)
			stmp3xxx_clearl(BM_SSP_CTRL0_READ,
					ss->regs + HW_SSP_CTRL0);
		else
			stmp3xxx_setl(BM_SSP_CTRL0_READ,
					ss->regs + HW_SSP_CTRL0);

		/* Run! */
		stmp3xxx_setl(BM_SSP_CTRL0_RUN, ss->regs + HW_SSP_CTRL0);

		if (!busy_wait(readl(ss->regs + HW_SSP_CTRL0) &
				BM_SSP_CTRL0_RUN))
			break;

		if (write)
			writel(*buf, ss->regs + HW_SSP_DATA);

		/* Set TRANSFER */
		stmp3xxx_setl(BM_SSP_CTRL0_DATA_XFER, ss->regs + HW_SSP_CTRL0);

		if (!write) {
			if (busy_wait((readl(ss->regs + HW_SSP_STATUS) &
					BM_SSP_STATUS_FIFO_EMPTY)))
				break;
			*buf = readl(ss->regs + HW_SSP_DATA) & 0xFF;
		}

		if (!busy_wait(readl(ss->regs + HW_SSP_CTRL0) &
					BM_SSP_CTRL0_RUN))
			break;

		/* advance to the next byte */
		buf++;
	}

	return len < 0 ? 0 : -ETIMEDOUT;
}

static int stmp_spi_handle_message(struct stmp_spi *ss, struct spi_message *m)
{
	bool first, last;
	struct spi_transfer *t, *tmp_t;
	int status = 0;
	int cs;

	cs = m->spi->chip_select;

	list_for_each_entry_safe(t, tmp_t, &m->transfers, transfer_list) {

		first = (&t->transfer_list == m->transfers.next);
		last = (&t->transfer_list == m->transfers.prev);

		if (first || t->speed_hz || t->bits_per_word)
			stmp_spi_setup_transfer(m->spi, t);

		/* reject "not last" transfers which request to change cs */
		if (t->cs_change && !last) {
			dev_err(&m->spi->dev,
				"Message with t->cs_change has been skipped\n");
			continue;
		}

		if (t->tx_buf) {
			status = pio ?
			   stmp_spi_txrx_pio(ss, cs, (void *)t->tx_buf,
				   t->len, first, last, true) :
			   stmp_spi_txrx_dma(ss, cs, (void *)t->tx_buf,
				   t->tx_dma, t->len, first, last, true);
#ifdef DEBUG
			if (t->len < 0x10)
				print_hex_dump_bytes("Tx ",
					DUMP_PREFIX_OFFSET,
					t->tx_buf, t->len);
			else
				pr_debug("Tx: %d bytes\n", t->len);
#endif
		}
		if (t->rx_buf) {
			status = pio ?
			   stmp_spi_txrx_pio(ss, cs, t->rx_buf,
				   t->len, first, last, false) :
			   stmp_spi_txrx_dma(ss, cs, t->rx_buf,
				   t->rx_dma, t->len, first, last, false);
#ifdef DEBUG
			if (t->len < 0x10)
				print_hex_dump_bytes("Rx ",
					DUMP_PREFIX_OFFSET,
					t->rx_buf, t->len);
			else
				pr_debug("Rx: %d bytes\n", t->len);
#endif
		}

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

		if (status)
			break;

	}
	return status;
}

/**
 * stmp_spi_handle - handle messages from the queue
 */
static void stmp_spi_handle(struct work_struct *w)
{
	struct stmp_spi *ss = container_of(w, struct stmp_spi, work);
	unsigned long flags;
	struct spi_message *m;

	spin_lock_irqsave(&ss->lock, flags);
	while (!list_empty(&ss->queue)) {
		m = list_entry(ss->queue.next, struct spi_message, queue);
		list_del_init(&m->queue);
		spin_unlock_irqrestore(&ss->lock, flags);

		m->status = stmp_spi_handle_message(ss, m);
		m->complete(m->context);

		spin_lock_irqsave(&ss->lock, flags);
	}
	spin_unlock_irqrestore(&ss->lock, flags);

	return;
}

/**
 * stmp_spi_transfer - perform message transfer.
 * Called indirectly from spi_async, queues all the messages to
 * spi_handle_message.
 * @spi: spi device
 * @m: message to be queued
 */
static int stmp_spi_transfer(struct spi_device *spi, struct spi_message *m)
{
	struct stmp_spi *ss = spi_master_get_devdata(spi->master);
	unsigned long flags;

	m->status = -EINPROGRESS;
	spin_lock_irqsave(&ss->lock, flags);
	list_add_tail(&m->queue, &ss->queue);
	queue_work(ss->workqueue, &ss->work);
	spin_unlock_irqrestore(&ss->lock, flags);
	return 0;
}

static irqreturn_t stmp_spi_irq(int irq, void *dev_id)
{
	struct stmp_spi *ss = dev_id;

	stmp3xxx_dma_clear_interrupt(ss->dma);
	complete(&ss->done);
	return IRQ_HANDLED;
}

static irqreturn_t stmp_spi_irq_err(int irq, void *dev_id)
{
	struct stmp_spi *ss = dev_id;
	u32 c1, st;

	c1 = readl(ss->regs + HW_SSP_CTRL1);
	st = readl(ss->regs + HW_SSP_STATUS);
	dev_err(ss->master_dev, "%s: status = 0x%08X, c1 = 0x%08X\n",
		__func__, st, c1);
	stmp3xxx_clearl(c1 & 0xCCCC0000, ss->regs + HW_SSP_CTRL1);

	return IRQ_HANDLED;
}

static int __devinit stmp_spi_probe(struct platform_device *dev)
{
	int err = 0;
	struct spi_master *master;
	struct stmp_spi *ss;
	struct resource *r;

	master = spi_alloc_master(&dev->dev, sizeof(struct stmp_spi));
	if (master == NULL) {
		err = -ENOMEM;
		goto out0;
	}
	master->flags = SPI_MASTER_HALF_DUPLEX;

	ss = spi_master_get_devdata(master);
	platform_set_drvdata(dev, master);

	/* Get resources(memory, IRQ) associated with the device */
	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
	if (r == NULL) {
		err = -ENODEV;
		goto out_put_master;
	}
	ss->regs = ioremap(r->start, resource_size(r));
	if (!ss->regs) {
		err = -EINVAL;
		goto out_put_master;
	}

	ss->master_dev = &dev->dev;
	ss->id = dev->id;

	INIT_WORK(&ss->work, stmp_spi_handle);
	INIT_LIST_HEAD(&ss->queue);
	spin_lock_init(&ss->lock);

	ss->workqueue = create_singlethread_workqueue(dev_name(&dev->dev));
	if (!ss->workqueue) {
		err = -ENXIO;
		goto out_put_master;
	}
	master->transfer = stmp_spi_transfer;
	master->setup = stmp_spi_setup;

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

	ss->irq = platform_get_irq(dev, 0);
	if (ss->irq < 0) {
		err = ss->irq;
		goto out_put_master;
	}
	ss->err_irq = platform_get_irq(dev, 1);
	if (ss->err_irq < 0) {
		err = ss->err_irq;
		goto out_put_master;
	}

	r = platform_get_resource(dev, IORESOURCE_DMA, 0);
	if (r == NULL) {
		err = -ENODEV;
		goto out_put_master;
	}

	ss->dma = r->start;
	err = stmp3xxx_dma_request(ss->dma, &dev->dev, dev_name(&dev->dev));
	if (err)
		goto out_put_master;

	err = stmp3xxx_dma_allocate_command(ss->dma, &ss->d);
	if (err)
		goto out_free_dma;

	master->bus_num = dev->id;
	master->num_chipselect = 1;

	/* SPI controller initializations */
	err = stmp_spi_init_hw(ss);
	if (err) {
		dev_dbg(&dev->dev, "cannot initialize hardware\n");
		goto out_free_dma_desc;
	}

	if (clock) {
		dev_info(&dev->dev, "clock rate forced to %d\n", clock);
		clk_set_rate(ss->clk, clock);
	}
	ss->speed_khz = clk_get_rate(ss->clk);
	ss->divider = 2;
	dev_info(&dev->dev, "max possible speed %d = %ld/%d kHz\n",
		ss->speed_khz, clk_get_rate(ss->clk), ss->divider);

	/* Register for SPI interrupt */
	err = request_irq(ss->irq, stmp_spi_irq, 0,
			  dev_name(&dev->dev), ss);
	if (err) {
		dev_dbg(&dev->dev, "request_irq failed, %d\n", err);
		goto out_release_hw;
	}

	/* ..and shared interrupt for all SSP controllers */
	err = request_irq(ss->err_irq, stmp_spi_irq_err, IRQF_SHARED,
			  dev_name(&dev->dev), ss);
	if (err) {
		dev_dbg(&dev->dev, "request_irq(error) failed, %d\n", err);
		goto out_free_irq;
	}

	err = spi_register_master(master);
	if (err) {
		dev_dbg(&dev->dev, "cannot register spi master, %d\n", err);
		goto out_free_irq_2;
	}
	dev_info(&dev->dev, "at (mapped) 0x%08X, irq=%d, bus %d, %s mode\n",
			(u32)ss->regs, ss->irq, master->bus_num,
			pio ? "PIO" : "DMA");
	return 0;

out_free_irq_2:
	free_irq(ss->err_irq, ss);
out_free_irq:
	free_irq(ss->irq, ss);
out_free_dma_desc:
	stmp3xxx_dma_free_command(ss->dma, &ss->d);
out_free_dma:
	stmp3xxx_dma_release(ss->dma);
out_release_hw:
	stmp_spi_release_hw(ss);
out_put_master:
	if (ss->workqueue)
		destroy_workqueue(ss->workqueue);
	if (ss->regs)
		iounmap(ss->regs);
	platform_set_drvdata(dev, NULL);
	spi_master_put(master);
out0:
	return err;
}

static int __devexit stmp_spi_remove(struct platform_device *dev)
{
	struct stmp_spi *ss;
	struct spi_master *master;

	master = platform_get_drvdata(dev);
	if (master == NULL)
		goto out0;
	ss = spi_master_get_devdata(master);

	spi_unregister_master(master);

	free_irq(ss->err_irq, ss);
	free_irq(ss->irq, ss);
	stmp3xxx_dma_free_command(ss->dma, &ss->d);
	stmp3xxx_dma_release(ss->dma);
	stmp_spi_release_hw(ss);
	destroy_workqueue(ss->workqueue);
	iounmap(ss->regs);
	spi_master_put(master);
	platform_set_drvdata(dev, NULL);
out0:
	return 0;
}

#ifdef CONFIG_PM
static int stmp_spi_suspend(struct platform_device *pdev, pm_message_t pmsg)
{
	struct stmp_spi *ss;
	struct spi_master *master;

	master = platform_get_drvdata(pdev);
	ss = spi_master_get_devdata(master);

	ss->saved_timings = readl(HW_SSP_TIMING + ss->regs);
	clk_disable(ss->clk);

	return 0;
}

static int stmp_spi_resume(struct platform_device *pdev)
{
	struct stmp_spi *ss;
	struct spi_master *master;

	master = platform_get_drvdata(pdev);
	ss = spi_master_get_devdata(master);

	clk_enable(ss->clk);
	stmp3xxx_reset_block(ss->regs, false);
	writel(ss->saved_timings, ss->regs + HW_SSP_TIMING);

	return 0;
}

#else
#define stmp_spi_suspend NULL
#define stmp_spi_resume  NULL
#endif

static struct platform_driver stmp_spi_driver = {
	.probe	= stmp_spi_probe,
	.remove	= __devexit_p(stmp_spi_remove),
	.driver = {
		.name = "stmp3xxx_ssp",
		.owner = THIS_MODULE,
	},
	.suspend = stmp_spi_suspend,
	.resume  = stmp_spi_resume,
};

static int __init stmp_spi_init(void)
{
	return platform_driver_register(&stmp_spi_driver);
}

static void __exit stmp_spi_exit(void)
{
	platform_driver_unregister(&stmp_spi_driver);
}

module_init(stmp_spi_init);
module_exit(stmp_spi_exit);
module_param(pio, int, S_IRUGO);
module_param(clock, int, S_IRUGO);
MODULE_AUTHOR("dmitry pervushin <dpervushin@embeddedalley.com>");
MODULE_DESCRIPTION("STMP3xxx SPI/SSP driver");
MODULE_LICENSE("GPL");