/*

   * MicroWire interface driver for OMAP

   *
   * Copyright 2003 MontaVista Software Inc. <source@mvista.com>
   *
   * Ported to 2.6 OMAP uwire interface.
   * Copyright (C) 2004 Texas Instruments.
   *
   * Generalization patches by Juha Yrjola <juha.yrjola@nokia.com>
   *
   * Copyright (C) 2005 David Brownell (ported to 2.6 SPI interface)
   * Copyright (C) 2006 Nokia
   *
   * Many updates by Imre Deak <imre.deak@nokia.com>
   *
   * 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 SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
   * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * 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.,
   * 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/platform_device.h>
  #include <linux/workqueue.h>
  #include <linux/interrupt.h>
  #include <linux/err.h>
  #include <linux/clk.h>

  #include <linux/slab.h>

  
  #include <linux/spi/spi.h>
  #include <linux/spi/spi_bitbang.h>

  #include <linux/module.h>

  
  #include <asm/system.h>
  #include <asm/irq.h>

  #include <mach/hardware.h>

  #include <asm/io.h>
  #include <asm/mach-types.h>

  #include <plat/mux.h>
  #include <plat/omap7xx.h>	/* OMAP7XX_IO_CONF registers */

  
  
  /* FIXME address is now a platform device resource,
   * and irqs should show there too...
   */
  #define UWIRE_BASE_PHYS		0xFFFB3000

  
  /* uWire Registers: */
  #define UWIRE_IO_SIZE 0x20
  #define UWIRE_TDR     0x00
  #define UWIRE_RDR     0x00
  #define UWIRE_CSR     0x01
  #define UWIRE_SR1     0x02
  #define UWIRE_SR2     0x03
  #define UWIRE_SR3     0x04
  #define UWIRE_SR4     0x05
  #define UWIRE_SR5     0x06
  
  /* CSR bits */
  #define	RDRB	(1 << 15)
  #define	CSRB	(1 << 14)
  #define	START	(1 << 13)
  #define	CS_CMD	(1 << 12)
  
  /* SR1 or SR2 bits */
  #define UWIRE_READ_FALLING_EDGE		0x0001
  #define UWIRE_READ_RISING_EDGE		0x0000
  #define UWIRE_WRITE_FALLING_EDGE	0x0000
  #define UWIRE_WRITE_RISING_EDGE		0x0002
  #define UWIRE_CS_ACTIVE_LOW		0x0000
  #define UWIRE_CS_ACTIVE_HIGH		0x0004
  #define UWIRE_FREQ_DIV_2		0x0000
  #define UWIRE_FREQ_DIV_4		0x0008
  #define UWIRE_FREQ_DIV_8		0x0010
  #define UWIRE_CHK_READY			0x0020
  #define UWIRE_CLK_INVERTED		0x0040
  
  
  struct uwire_spi {
  	struct spi_bitbang	bitbang;
  	struct clk		*ck;
  };
  
  struct uwire_state {
  	unsigned	bits_per_word;
  	unsigned	div1_idx;
  };
  
  /* REVISIT compile time constant for idx_shift? */

  /*
   * Or, put it in a structure which is used throughout the driver;
   * that avoids having to issue two loads for each bit of static data.
   */

  static unsigned int uwire_idx_shift;

  static void __iomem *uwire_base;

  
  static inline void uwire_write_reg(int idx, u16 val)
  {

  	__raw_writew(val, uwire_base + (idx << uwire_idx_shift));

  }
  
  static inline u16 uwire_read_reg(int idx)
  {

  	return __raw_readw(uwire_base + (idx << uwire_idx_shift));

  }
  
  static inline void omap_uwire_configure_mode(u8 cs, unsigned long flags)
  {
  	u16	w, val = 0;
  	int	shift, reg;
  
  	if (flags & UWIRE_CLK_INVERTED)
  		val ^= 0x03;
  	val = flags & 0x3f;
  	if (cs & 1)
  		shift = 6;
  	else
  		shift = 0;
  	if (cs <= 1)
  		reg = UWIRE_SR1;
  	else
  		reg = UWIRE_SR2;
  
  	w = uwire_read_reg(reg);
  	w &= ~(0x3f << shift);
  	w |= val << shift;
  	uwire_write_reg(reg, w);
  }
  
  static int wait_uwire_csr_flag(u16 mask, u16 val, int might_not_catch)
  {
  	u16 w;
  	int c = 0;
  	unsigned long max_jiffies = jiffies + HZ;
  
  	for (;;) {
  		w = uwire_read_reg(UWIRE_CSR);
  		if ((w & mask) == val)
  			break;
  		if (time_after(jiffies, max_jiffies)) {
  			printk(KERN_ERR "%s: timeout. reg=%#06x "
  					"mask=%#06x val=%#06x
  ",

  			       __func__, w, mask, val);

  			return -1;
  		}
  		c++;
  		if (might_not_catch && c > 64)
  			break;
  	}
  	return 0;
  }
  
  static void uwire_set_clk1_div(int div1_idx)
  {
  	u16 w;
  
  	w = uwire_read_reg(UWIRE_SR3);
  	w &= ~(0x03 << 1);
  	w |= div1_idx << 1;
  	uwire_write_reg(UWIRE_SR3, w);
  }
  
  static void uwire_chipselect(struct spi_device *spi, int value)
  {
  	struct	uwire_state *ust = spi->controller_state;
  	u16	w;
  	int	old_cs;
  
  
  	BUG_ON(wait_uwire_csr_flag(CSRB, 0, 0));
  
  	w = uwire_read_reg(UWIRE_CSR);
  	old_cs = (w >> 10) & 0x03;
  	if (value == BITBANG_CS_INACTIVE || old_cs != spi->chip_select) {
  		/* Deselect this CS, or the previous CS */
  		w &= ~CS_CMD;
  		uwire_write_reg(UWIRE_CSR, w);
  	}
  	/* activate specfied chipselect */
  	if (value == BITBANG_CS_ACTIVE) {
  		uwire_set_clk1_div(ust->div1_idx);
  		/* invert clock? */
  		if (spi->mode & SPI_CPOL)
  			uwire_write_reg(UWIRE_SR4, 1);
  		else
  			uwire_write_reg(UWIRE_SR4, 0);
  
  		w = spi->chip_select << 10;
  		w |= CS_CMD;
  		uwire_write_reg(UWIRE_CSR, w);
  	}
  }
  
  static int uwire_txrx(struct spi_device *spi, struct spi_transfer *t)
  {
  	struct uwire_state *ust = spi->controller_state;
  	unsigned	len = t->len;
  	unsigned	bits = ust->bits_per_word;
  	unsigned	bytes;
  	u16		val, w;

  	int		status = 0;

  
  	if (!t->tx_buf && !t->rx_buf)
  		return 0;
  
  	/* Microwire doesn't read and write concurrently */
  	if (t->tx_buf && t->rx_buf)
  		return -EPERM;
  
  	w = spi->chip_select << 10;
  	w |= CS_CMD;
  
  	if (t->tx_buf) {
  		const u8	*buf = t->tx_buf;
  
  		/* NOTE:  DMA could be used for TX transfers */
  
  		/* write one or two bytes at a time */
  		while (len >= 1) {
  			/* tx bit 15 is first sent; we byteswap multibyte words
  			 * (msb-first) on the way out from memory.
  			 */
  			val = *buf++;
  			if (bits > 8) {
  				bytes = 2;
  				val |= *buf++ << 8;
  			} else
  				bytes = 1;
  			val <<= 16 - bits;
  
  #ifdef	VERBOSE
  			pr_debug("%s: write-%d =%04x
  ",

  					dev_name(&spi->dev), bits, val);

  #endif
  			if (wait_uwire_csr_flag(CSRB, 0, 0))
  				goto eio;
  
  			uwire_write_reg(UWIRE_TDR, val);
  
  			/* start write */
  			val = START | w | (bits << 5);
  
  			uwire_write_reg(UWIRE_CSR, val);
  			len -= bytes;
  
  			/* Wait till write actually starts.
  			 * This is needed with MPU clock 60+ MHz.
  			 * REVISIT: we may not have time to catch it...
  			 */
  			if (wait_uwire_csr_flag(CSRB, CSRB, 1))
  				goto eio;
  
  			status += bytes;
  		}
  
  		/* REVISIT:  save this for later to get more i/o overlap */
  		if (wait_uwire_csr_flag(CSRB, 0, 0))
  			goto eio;
  
  	} else if (t->rx_buf) {
  		u8		*buf = t->rx_buf;
  
  		/* read one or two bytes at a time */
  		while (len) {
  			if (bits > 8) {
  				bytes = 2;
  			} else
  				bytes = 1;
  
  			/* start read */
  			val = START | w | (bits << 0);
  			uwire_write_reg(UWIRE_CSR, val);
  			len -= bytes;
  
  			/* Wait till read actually starts */
  			(void) wait_uwire_csr_flag(CSRB, CSRB, 1);
  
  			if (wait_uwire_csr_flag(RDRB | CSRB,
  						RDRB, 0))
  				goto eio;
  
  			/* rx bit 0 is last received; multibyte words will
  			 * be properly byteswapped on the way to memory.
  			 */
  			val = uwire_read_reg(UWIRE_RDR);
  			val &= (1 << bits) - 1;
  			*buf++ = (u8) val;
  			if (bytes == 2)
  				*buf++ = val >> 8;
  			status += bytes;
  #ifdef	VERBOSE
  			pr_debug("%s: read-%d =%04x
  ",

  					dev_name(&spi->dev), bits, val);

  #endif
  
  		}
  	}
  	return status;
  eio:
  	return -EIO;
  }
  
  static int uwire_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
  {
  	struct uwire_state	*ust = spi->controller_state;
  	struct uwire_spi	*uwire;
  	unsigned		flags = 0;
  	unsigned		bits;
  	unsigned		hz;
  	unsigned long		rate;
  	int			div1_idx;
  	int			div1;
  	int			div2;
  	int			status;
  
  	uwire = spi_master_get_devdata(spi->master);
  
  	if (spi->chip_select > 3) {

  		pr_debug("%s: cs%d?
  ", dev_name(&spi->dev), spi->chip_select);

  		status = -ENODEV;
  		goto done;
  	}
  
  	bits = spi->bits_per_word;
  	if (t != NULL && t->bits_per_word)
  		bits = t->bits_per_word;

  
  	if (bits > 16) {

  		pr_debug("%s: wordsize %d?
  ", dev_name(&spi->dev), bits);

  		status = -ENODEV;
  		goto done;
  	}
  	ust->bits_per_word = bits;
  
  	/* mode 0..3, clock inverted separately;
  	 * standard nCS signaling;
  	 * don't treat DI=high as "not ready"
  	 */
  	if (spi->mode & SPI_CS_HIGH)
  		flags |= UWIRE_CS_ACTIVE_HIGH;
  
  	if (spi->mode & SPI_CPOL)
  		flags |= UWIRE_CLK_INVERTED;
  
  	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
  	case SPI_MODE_0:
  	case SPI_MODE_3:

  		flags |= UWIRE_WRITE_FALLING_EDGE | UWIRE_READ_RISING_EDGE;

  		break;
  	case SPI_MODE_1:
  	case SPI_MODE_2:

  		flags |= UWIRE_WRITE_RISING_EDGE | UWIRE_READ_FALLING_EDGE;

  		break;
  	}
  
  	/* assume it's already enabled */
  	rate = clk_get_rate(uwire->ck);
  
  	hz = spi->max_speed_hz;
  	if (t != NULL && t->speed_hz)
  		hz = t->speed_hz;
  
  	if (!hz) {

  		pr_debug("%s: zero speed?
  ", dev_name(&spi->dev));

  		status = -EINVAL;
  		goto done;
  	}
  
  	/* F_INT = mpu_xor_clk / DIV1 */
  	for (div1_idx = 0; div1_idx < 4; div1_idx++) {
  		switch (div1_idx) {
  		case 0:
  			div1 = 2;
  			break;
  		case 1:
  			div1 = 4;
  			break;
  		case 2:
  			div1 = 7;
  			break;
  		default:
  		case 3:
  			div1 = 10;
  			break;
  		}
  		div2 = (rate / div1 + hz - 1) / hz;
  		if (div2 <= 8)
  			break;
  	}
  	if (div1_idx == 4) {
  		pr_debug("%s: lowest clock %ld, need %d
  ",

  			dev_name(&spi->dev), rate / 10 / 8, hz);

  		status = -EDOM;
  		goto done;
  	}
  
  	/* we have to cache this and reset in uwire_chipselect as this is a
  	 * global parameter and another uwire device can change it under
  	 * us */
  	ust->div1_idx = div1_idx;
  	uwire_set_clk1_div(div1_idx);
  
  	rate /= div1;
  
  	switch (div2) {
  	case 0:
  	case 1:
  	case 2:
  		flags |= UWIRE_FREQ_DIV_2;
  		rate /= 2;
  		break;
  	case 3:
  	case 4:
  		flags |= UWIRE_FREQ_DIV_4;
  		rate /= 4;
  		break;
  	case 5:
  	case 6:
  	case 7:
  	case 8:
  		flags |= UWIRE_FREQ_DIV_8;
  		rate /= 8;
  		break;
  	}
  	omap_uwire_configure_mode(spi->chip_select, flags);
  	pr_debug("%s: uwire flags %02x, armxor %lu KHz, SCK %lu KHz
  ",

  			__func__, flags,

  			clk_get_rate(uwire->ck) / 1000,
  			rate / 1000);
  	status = 0;
  done:
  	return status;
  }
  
  static int uwire_setup(struct spi_device *spi)
  {
  	struct uwire_state *ust = spi->controller_state;
  
  	if (ust == NULL) {
  		ust = kzalloc(sizeof(*ust), GFP_KERNEL);
  		if (ust == NULL)
  			return -ENOMEM;
  		spi->controller_state = ust;
  	}
  
  	return uwire_setup_transfer(spi, NULL);
  }

  static void uwire_cleanup(struct spi_device *spi)

  {
  	kfree(spi->controller_state);
  }
  
  static void uwire_off(struct uwire_spi *uwire)
  {
  	uwire_write_reg(UWIRE_SR3, 0);
  	clk_disable(uwire->ck);
  	clk_put(uwire->ck);
  	spi_master_put(uwire->bitbang.master);
  }

  static int __init uwire_probe(struct platform_device *pdev)

  {
  	struct spi_master	*master;
  	struct uwire_spi	*uwire;
  	int			status;
  
  	master = spi_alloc_master(&pdev->dev, sizeof *uwire);
  	if (!master)
  		return -ENODEV;
  
  	uwire = spi_master_get_devdata(master);

  
  	uwire_base = ioremap(UWIRE_BASE_PHYS, UWIRE_IO_SIZE);
  	if (!uwire_base) {
  		dev_dbg(&pdev->dev, "can't ioremap UWIRE
  ");
  		spi_master_put(master);
  		return -ENOMEM;
  	}

  	dev_set_drvdata(&pdev->dev, uwire);

  	uwire->ck = clk_get(&pdev->dev, "fck");
  	if (IS_ERR(uwire->ck)) {
  		status = PTR_ERR(uwire->ck);
  		dev_dbg(&pdev->dev, "no functional clock?
  ");

  		spi_master_put(master);

  		return status;

  	}
  	clk_enable(uwire->ck);

  	if (cpu_is_omap7xx())

  		uwire_idx_shift = 1;
  	else
  		uwire_idx_shift = 2;
  
  	uwire_write_reg(UWIRE_SR3, 1);

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

  	master->flags = SPI_MASTER_HALF_DUPLEX;

  	master->bus_num = 2;	/* "official" */
  	master->num_chipselect = 4;
  	master->setup = uwire_setup;
  	master->cleanup = uwire_cleanup;
  
  	uwire->bitbang.master = master;
  	uwire->bitbang.chipselect = uwire_chipselect;
  	uwire->bitbang.setup_transfer = uwire_setup_transfer;
  	uwire->bitbang.txrx_bufs = uwire_txrx;
  
  	status = spi_bitbang_start(&uwire->bitbang);

  	if (status < 0) {

  		uwire_off(uwire);

  		iounmap(uwire_base);
  	}

  	return status;
  }

  static int __exit uwire_remove(struct platform_device *pdev)

  {
  	struct uwire_spi	*uwire = dev_get_drvdata(&pdev->dev);
  	int			status;
  
  	// FIXME remove all child devices, somewhere ...
  
  	status = spi_bitbang_stop(&uwire->bitbang);
  	uwire_off(uwire);

  	iounmap(uwire_base);

  	return status;
  }

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

  static struct platform_driver uwire_driver = {
  	.driver = {
  		.name		= "omap_uwire",

  		.owner		= THIS_MODULE,
  	},

  	.remove		= __exit_p(uwire_remove),

  	// suspend ... unuse ck
  	// resume ... use ck
  };
  
  static int __init omap_uwire_init(void)
  {
  	/* FIXME move these into the relevant board init code. also, include
  	 * H3 support; it uses tsc2101 like H2 (on a different chipselect).
  	 */
  
  	if (machine_is_omap_h2()) {
  		/* defaults: W21 SDO, U18 SDI, V19 SCL */
  		omap_cfg_reg(N14_1610_UWIRE_CS0);
  		omap_cfg_reg(N15_1610_UWIRE_CS1);
  	}
  	if (machine_is_omap_perseus2()) {
  		/* configure pins: MPU_UW_nSCS1, MPU_UW_SDO, MPU_UW_SCLK */

  		int val = omap_readl(OMAP7XX_IO_CONF_9) & ~0x00EEE000;
  		omap_writel(val | 0x00AAA000, OMAP7XX_IO_CONF_9);

  	}

  	return platform_driver_probe(&uwire_driver, uwire_probe);

  }
  
  static void __exit omap_uwire_exit(void)
  {
  	platform_driver_unregister(&uwire_driver);
  }
  
  subsys_initcall(omap_uwire_init);
  module_exit(omap_uwire_exit);
  
  MODULE_LICENSE("GPL");