/*

   * MCP23S08 SPI/GPIO gpio expander driver

   */
  
  #include <linux/kernel.h>
  #include <linux/device.h>

  #include <linux/mutex.h>

  #include <linux/module.h>

  #include <linux/gpio.h>

  #include <linux/i2c.h>

  #include <linux/spi/spi.h>
  #include <linux/spi/mcp23s08.h>

  #include <linux/slab.h>

  #include <asm/byteorder.h>

  /**
   * MCP types supported by driver
   */
  #define MCP_TYPE_S08	0
  #define MCP_TYPE_S17	1

  #define MCP_TYPE_008	2
  #define MCP_TYPE_017	3

  
  /* Registers are all 8 bits wide.
   *
   * The mcp23s17 has twice as many bits, and can be configured to work
   * with either 16 bit registers or with two adjacent 8 bit banks.

   */
  #define MCP_IODIR	0x00		/* init/reset:  all ones */
  #define MCP_IPOL	0x01
  #define MCP_GPINTEN	0x02
  #define MCP_DEFVAL	0x03
  #define MCP_INTCON	0x04
  #define MCP_IOCON	0x05
  #	define IOCON_SEQOP	(1 << 5)
  #	define IOCON_HAEN	(1 << 3)
  #	define IOCON_ODR	(1 << 2)
  #	define IOCON_INTPOL	(1 << 1)
  #define MCP_GPPU	0x06
  #define MCP_INTF	0x07
  #define MCP_INTCAP	0x08
  #define MCP_GPIO	0x09
  #define MCP_OLAT	0x0a

  struct mcp23s08;
  
  struct mcp23s08_ops {
  	int	(*read)(struct mcp23s08 *mcp, unsigned reg);
  	int	(*write)(struct mcp23s08 *mcp, unsigned reg, unsigned val);
  	int	(*read_regs)(struct mcp23s08 *mcp, unsigned reg,
  			     u16 *vals, unsigned n);
  };

  struct mcp23s08 {

  	u8			addr;

  	u16			cache[11];

  	/* lock protects the cached values */
  	struct mutex		lock;

  
  	struct gpio_chip	chip;

  	const struct mcp23s08_ops	*ops;

  	void			*data; /* ops specific data */

  };

  /* A given spi_device can represent up to eight mcp23sxx chips

   * sharing the same chipselect but using different addresses
   * (e.g. chips #0 and #3 might be populated, but not #1 or $2).
   * Driver data holds all the per-chip data.
   */
  struct mcp23s08_driver_data {
  	unsigned		ngpio;

  	struct mcp23s08		*mcp[8];

  	struct mcp23s08		chip[];
  };

  /*----------------------------------------------------------------------*/
  
  #ifdef CONFIG_I2C
  
  static int mcp23008_read(struct mcp23s08 *mcp, unsigned reg)
  {
  	return i2c_smbus_read_byte_data(mcp->data, reg);
  }
  
  static int mcp23008_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
  {
  	return i2c_smbus_write_byte_data(mcp->data, reg, val);
  }
  
  static int
  mcp23008_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
  {
  	while (n--) {
  		int ret = mcp23008_read(mcp, reg++);
  		if (ret < 0)
  			return ret;
  		*vals++ = ret;
  	}
  
  	return 0;
  }
  
  static int mcp23017_read(struct mcp23s08 *mcp, unsigned reg)
  {
  	return i2c_smbus_read_word_data(mcp->data, reg << 1);
  }
  
  static int mcp23017_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
  {
  	return i2c_smbus_write_word_data(mcp->data, reg << 1, val);
  }
  
  static int
  mcp23017_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
  {
  	while (n--) {
  		int ret = mcp23017_read(mcp, reg++);
  		if (ret < 0)
  			return ret;
  		*vals++ = ret;
  	}
  
  	return 0;
  }
  
  static const struct mcp23s08_ops mcp23008_ops = {
  	.read		= mcp23008_read,
  	.write		= mcp23008_write,
  	.read_regs	= mcp23008_read_regs,
  };
  
  static const struct mcp23s08_ops mcp23017_ops = {
  	.read		= mcp23017_read,
  	.write		= mcp23017_write,
  	.read_regs	= mcp23017_read_regs,
  };
  
  #endif /* CONFIG_I2C */
  
  /*----------------------------------------------------------------------*/

  #ifdef CONFIG_SPI_MASTER

  static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
  {
  	u8	tx[2], rx[1];
  	int	status;
  
  	tx[0] = mcp->addr | 0x01;
  	tx[1] = reg;

  	status = spi_write_then_read(mcp->data, tx, sizeof tx, rx, sizeof rx);

  	return (status < 0) ? status : rx[0];
  }

  static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)

  {
  	u8	tx[3];
  
  	tx[0] = mcp->addr;
  	tx[1] = reg;
  	tx[2] = val;

  	return spi_write_then_read(mcp->data, tx, sizeof tx, NULL, 0);

  }
  
  static int

  mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)

  {

  	u8	tx[2], *tmp;
  	int	status;

  
  	if ((n + reg) > sizeof mcp->cache)
  		return -EINVAL;
  	tx[0] = mcp->addr | 0x01;
  	tx[1] = reg;

  
  	tmp = (u8 *)vals;

  	status = spi_write_then_read(mcp->data, tx, sizeof tx, tmp, n);

  	if (status >= 0) {
  		while (n--)
  			vals[n] = tmp[n]; /* expand to 16bit */
  	}
  	return status;
  }
  
  static int mcp23s17_read(struct mcp23s08 *mcp, unsigned reg)
  {
  	u8	tx[2], rx[2];
  	int	status;
  
  	tx[0] = mcp->addr | 0x01;
  	tx[1] = reg << 1;

  	status = spi_write_then_read(mcp->data, tx, sizeof tx, rx, sizeof rx);

  	return (status < 0) ? status : (rx[0] | (rx[1] << 8));
  }
  
  static int mcp23s17_write(struct mcp23s08 *mcp, unsigned reg, unsigned val)
  {
  	u8	tx[4];
  
  	tx[0] = mcp->addr;
  	tx[1] = reg << 1;
  	tx[2] = val;
  	tx[3] = val >> 8;

  	return spi_write_then_read(mcp->data, tx, sizeof tx, NULL, 0);

  }
  
  static int
  mcp23s17_read_regs(struct mcp23s08 *mcp, unsigned reg, u16 *vals, unsigned n)
  {
  	u8	tx[2];
  	int	status;
  
  	if ((n + reg) > sizeof mcp->cache)
  		return -EINVAL;
  	tx[0] = mcp->addr | 0x01;
  	tx[1] = reg << 1;

  	status = spi_write_then_read(mcp->data, tx, sizeof tx,

  				     (u8 *)vals, n * 2);
  	if (status >= 0) {
  		while (n--)
  			vals[n] = __le16_to_cpu((__le16)vals[n]);
  	}
  
  	return status;

  }

  static const struct mcp23s08_ops mcp23s08_ops = {
  	.read		= mcp23s08_read,
  	.write		= mcp23s08_write,
  	.read_regs	= mcp23s08_read_regs,
  };
  
  static const struct mcp23s08_ops mcp23s17_ops = {
  	.read		= mcp23s17_read,
  	.write		= mcp23s17_write,
  	.read_regs	= mcp23s17_read_regs,
  };

  #endif /* CONFIG_SPI_MASTER */

  /*----------------------------------------------------------------------*/
  
  static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
  {
  	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
  	int status;
  
  	mutex_lock(&mcp->lock);
  	mcp->cache[MCP_IODIR] |= (1 << offset);

  	status = mcp->ops->write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);

  	mutex_unlock(&mcp->lock);
  	return status;
  }
  
  static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
  {
  	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
  	int status;
  
  	mutex_lock(&mcp->lock);
  
  	/* REVISIT reading this clears any IRQ ... */

  	status = mcp->ops->read(mcp, MCP_GPIO);

  	if (status < 0)
  		status = 0;
  	else {
  		mcp->cache[MCP_GPIO] = status;
  		status = !!(status & (1 << offset));
  	}
  	mutex_unlock(&mcp->lock);
  	return status;
  }
  
  static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
  {

  	unsigned olat = mcp->cache[MCP_OLAT];

  
  	if (value)
  		olat |= mask;
  	else
  		olat &= ~mask;
  	mcp->cache[MCP_OLAT] = olat;

  	return mcp->ops->write(mcp, MCP_OLAT, olat);

  }
  
  static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
  {
  	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);

  	unsigned mask = 1 << offset;

  
  	mutex_lock(&mcp->lock);
  	__mcp23s08_set(mcp, mask, value);
  	mutex_unlock(&mcp->lock);
  }
  
  static int
  mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
  {
  	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);

  	unsigned mask = 1 << offset;

  	int status;
  
  	mutex_lock(&mcp->lock);
  	status = __mcp23s08_set(mcp, mask, value);
  	if (status == 0) {
  		mcp->cache[MCP_IODIR] &= ~mask;

  		status = mcp->ops->write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);

  	}
  	mutex_unlock(&mcp->lock);
  	return status;
  }
  
  /*----------------------------------------------------------------------*/
  
  #ifdef CONFIG_DEBUG_FS
  
  #include <linux/seq_file.h>
  
  /*
   * This shows more info than the generic gpio dump code:
   * pullups, deglitching, open drain drive.
   */
  static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
  {
  	struct mcp23s08	*mcp;
  	char		bank;

  	int		t;

  	unsigned	mask;
  
  	mcp = container_of(chip, struct mcp23s08, chip);
  
  	/* NOTE: we only handle one bank for now ... */

  	bank = '0' + ((mcp->addr >> 1) & 0x7);

  
  	mutex_lock(&mcp->lock);

  	t = mcp->ops->read_regs(mcp, 0, mcp->cache, ARRAY_SIZE(mcp->cache));

  	if (t < 0) {
  		seq_printf(s, " I/O ERROR %d
  ", t);
  		goto done;
  	}

  	for (t = 0, mask = 1; t < chip->ngpio; t++, mask <<= 1) {

  		const char	*label;
  
  		label = gpiochip_is_requested(chip, t);
  		if (!label)
  			continue;
  
  		seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
  			chip->base + t, bank, t, label,
  			(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
  			(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
  			(mcp->cache[MCP_GPPU] & mask) ? "  " : "up");
  		/* NOTE:  ignoring the irq-related registers */
  		seq_printf(s, "
  ");
  	}
  done:
  	mutex_unlock(&mcp->lock);
  }
  
  #else
  #define mcp23s08_dbg_show	NULL
  #endif
  
  /*----------------------------------------------------------------------*/

  static int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev,
  			      void *data, unsigned addr,

  			      unsigned type, unsigned base, unsigned pullups)

  {

  	int status;

  	mutex_init(&mcp->lock);

  	mcp->data = data;
  	mcp->addr = addr;

  	mcp->chip.direction_input = mcp23s08_direction_input;
  	mcp->chip.get = mcp23s08_get;
  	mcp->chip.direction_output = mcp23s08_direction_output;
  	mcp->chip.set = mcp23s08_set;
  	mcp->chip.dbg_show = mcp23s08_dbg_show;

  	switch (type) {
  #ifdef CONFIG_SPI_MASTER
  	case MCP_TYPE_S08:

  		mcp->ops = &mcp23s08_ops;
  		mcp->chip.ngpio = 8;
  		mcp->chip.label = "mcp23s08";

  		break;
  
  	case MCP_TYPE_S17:
  		mcp->ops = &mcp23s17_ops;
  		mcp->chip.ngpio = 16;
  		mcp->chip.label = "mcp23s17";
  		break;
  #endif /* CONFIG_SPI_MASTER */

  #ifdef CONFIG_I2C
  	case MCP_TYPE_008:
  		mcp->ops = &mcp23008_ops;
  		mcp->chip.ngpio = 8;
  		mcp->chip.label = "mcp23008";
  		break;
  
  	case MCP_TYPE_017:
  		mcp->ops = &mcp23017_ops;
  		mcp->chip.ngpio = 16;
  		mcp->chip.label = "mcp23017";
  		break;
  #endif /* CONFIG_I2C */

  	default:
  		dev_err(dev, "invalid device type (%d)
  ", type);
  		return -EINVAL;

  	}

  	mcp->chip.base = base;

  	mcp->chip.can_sleep = 1;

  	mcp->chip.dev = dev;

  	mcp->chip.owner = THIS_MODULE;

  	/* verify MCP_IOCON.SEQOP = 0, so sequential reads work,
  	 * and MCP_IOCON.HAEN = 1, so we work with all chips.
  	 */

  	status = mcp->ops->read(mcp, MCP_IOCON);

  	if (status < 0)
  		goto fail;

  	if ((status & IOCON_SEQOP) || !(status & IOCON_HAEN)) {

  		/* mcp23s17 has IOCON twice, make sure they are in sync */
  		status &= ~(IOCON_SEQOP | (IOCON_SEQOP << 8));
  		status |= IOCON_HAEN | (IOCON_HAEN << 8);
  		status = mcp->ops->write(mcp, MCP_IOCON, status);

  		if (status < 0)
  			goto fail;
  	}
  
  	/* configure ~100K pullups */

  	status = mcp->ops->write(mcp, MCP_GPPU, pullups);

  	if (status < 0)
  		goto fail;

  	status = mcp->ops->read_regs(mcp, 0, mcp->cache, ARRAY_SIZE(mcp->cache));

  	if (status < 0)
  		goto fail;
  
  	/* disable inverter on input */
  	if (mcp->cache[MCP_IPOL] != 0) {
  		mcp->cache[MCP_IPOL] = 0;

  		status = mcp->ops->write(mcp, MCP_IPOL, 0);
  		if (status < 0)
  			goto fail;

  	}
  
  	/* disable irqs */
  	if (mcp->cache[MCP_GPINTEN] != 0) {
  		mcp->cache[MCP_GPINTEN] = 0;

  		status = mcp->ops->write(mcp, MCP_GPINTEN, 0);

  		if (status < 0)
  			goto fail;

  	}
  
  	status = gpiochip_add(&mcp->chip);

  fail:
  	if (status < 0)

  		dev_dbg(dev, "can't setup chip %d, --> %d
  ",
  			addr, status);

  	return status;
  }

  /*----------------------------------------------------------------------*/
  
  #ifdef CONFIG_I2C
  
  static int __devinit mcp230xx_probe(struct i2c_client *client,
  				    const struct i2c_device_id *id)
  {
  	struct mcp23s08_platform_data *pdata;
  	struct mcp23s08 *mcp;
  	int status;
  
  	pdata = client->dev.platform_data;
  	if (!pdata || !gpio_is_valid(pdata->base)) {
  		dev_dbg(&client->dev, "invalid or missing platform data
  ");
  		return -EINVAL;
  	}
  
  	mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
  	if (!mcp)
  		return -ENOMEM;
  
  	status = mcp23s08_probe_one(mcp, &client->dev, client, client->addr,
  				    id->driver_data, pdata->base,
  				    pdata->chip[0].pullups);
  	if (status)
  		goto fail;
  
  	i2c_set_clientdata(client, mcp);
  
  	return 0;
  
  fail:
  	kfree(mcp);
  
  	return status;
  }
  
  static int __devexit mcp230xx_remove(struct i2c_client *client)
  {
  	struct mcp23s08 *mcp = i2c_get_clientdata(client);
  	int status;
  
  	status = gpiochip_remove(&mcp->chip);
  	if (status == 0)
  		kfree(mcp);
  
  	return status;
  }
  
  static const struct i2c_device_id mcp230xx_id[] = {
  	{ "mcp23008", MCP_TYPE_008 },
  	{ "mcp23017", MCP_TYPE_017 },
  	{ },
  };
  MODULE_DEVICE_TABLE(i2c, mcp230xx_id);
  
  static struct i2c_driver mcp230xx_driver = {
  	.driver = {
  		.name	= "mcp230xx",
  		.owner	= THIS_MODULE,
  	},
  	.probe		= mcp230xx_probe,
  	.remove		= __devexit_p(mcp230xx_remove),
  	.id_table	= mcp230xx_id,
  };
  
  static int __init mcp23s08_i2c_init(void)
  {
  	return i2c_add_driver(&mcp230xx_driver);
  }
  
  static void mcp23s08_i2c_exit(void)
  {
  	i2c_del_driver(&mcp230xx_driver);
  }
  
  #else
  
  static int __init mcp23s08_i2c_init(void) { return 0; }
  static void mcp23s08_i2c_exit(void) { }
  
  #endif /* CONFIG_I2C */
  
  /*----------------------------------------------------------------------*/

  #ifdef CONFIG_SPI_MASTER

  static int mcp23s08_probe(struct spi_device *spi)
  {
  	struct mcp23s08_platform_data	*pdata;
  	unsigned			addr;
  	unsigned			chips = 0;
  	struct mcp23s08_driver_data	*data;

  	int				status, type;

  	unsigned			base;

  	type = spi_get_device_id(spi)->driver_data;

  	pdata = spi->dev.platform_data;

  	if (!pdata || !gpio_is_valid(pdata->base)) {
  		dev_dbg(&spi->dev, "invalid or missing platform data
  ");
  		return -EINVAL;
  	}

  	for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {

  		if (!pdata->chip[addr].is_present)
  			continue;
  		chips++;

  		if ((type == MCP_TYPE_S08) && (addr > 3)) {
  			dev_err(&spi->dev,
  				"mcp23s08 only supports address 0..3
  ");
  			return -EINVAL;
  		}

  	}
  	if (!chips)
  		return -ENODEV;
  
  	data = kzalloc(sizeof *data + chips * sizeof(struct mcp23s08),
  			GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  	spi_set_drvdata(spi, data);
  
  	base = pdata->base;

  	for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {

  		if (!pdata->chip[addr].is_present)
  			continue;
  		chips--;
  		data->mcp[addr] = &data->chip[chips];

  		status = mcp23s08_probe_one(data->mcp[addr], &spi->dev, spi,
  					    0x40 | (addr << 1), type, base,

  					    pdata->chip[addr].pullups);

  		if (status < 0)
  			goto fail;

  
  		base += (type == MCP_TYPE_S17) ? 16 : 8;

  	}
  	data->ngpio = base - pdata->base;

  
  	/* NOTE:  these chips have a relatively sane IRQ framework, with
  	 * per-signal masking and level/edge triggering.  It's not yet
  	 * handled here...
  	 */

  	return 0;
  
  fail:

  	for (addr = 0; addr < ARRAY_SIZE(data->mcp); addr++) {

  		int tmp;
  
  		if (!data->mcp[addr])
  			continue;
  		tmp = gpiochip_remove(&data->mcp[addr]->chip);
  		if (tmp < 0)
  			dev_err(&spi->dev, "%s --> %d
  ", "remove", tmp);
  	}
  	kfree(data);

  	return status;
  }
  
  static int mcp23s08_remove(struct spi_device *spi)
  {

  	struct mcp23s08_driver_data	*data = spi_get_drvdata(spi);

  	unsigned			addr;

  	int				status = 0;

  	for (addr = 0; addr < ARRAY_SIZE(data->mcp); addr++) {

  		int tmp;
  
  		if (!data->mcp[addr])
  			continue;
  
  		tmp = gpiochip_remove(&data->mcp[addr]->chip);
  		if (tmp < 0) {
  			dev_err(&spi->dev, "%s --> %d
  ", "remove", tmp);
  			status = tmp;
  		}
  	}

  	if (status == 0)

  		kfree(data);

  	return status;
  }

  static const struct spi_device_id mcp23s08_ids[] = {
  	{ "mcp23s08", MCP_TYPE_S08 },
  	{ "mcp23s17", MCP_TYPE_S17 },
  	{ },
  };
  MODULE_DEVICE_TABLE(spi, mcp23s08_ids);

  static struct spi_driver mcp23s08_driver = {
  	.probe		= mcp23s08_probe,
  	.remove		= mcp23s08_remove,

  	.id_table	= mcp23s08_ids,

  	.driver = {
  		.name	= "mcp23s08",
  		.owner	= THIS_MODULE,
  	},
  };

  static int __init mcp23s08_spi_init(void)
  {
  	return spi_register_driver(&mcp23s08_driver);
  }
  
  static void mcp23s08_spi_exit(void)
  {
  	spi_unregister_driver(&mcp23s08_driver);
  }
  
  #else
  
  static int __init mcp23s08_spi_init(void) { return 0; }
  static void mcp23s08_spi_exit(void) { }
  
  #endif /* CONFIG_SPI_MASTER */

  /*----------------------------------------------------------------------*/
  
  static int __init mcp23s08_init(void)
  {

  	int ret;
  
  	ret = mcp23s08_spi_init();
  	if (ret)
  		goto spi_fail;
  
  	ret = mcp23s08_i2c_init();
  	if (ret)
  		goto i2c_fail;
  
  	return 0;
  
   i2c_fail:
  	mcp23s08_spi_exit();
   spi_fail:
  	return ret;

  }

  /* register after spi/i2c postcore initcall and before

   * subsys initcalls that may rely on these GPIOs
   */
  subsys_initcall(mcp23s08_init);

  
  static void __exit mcp23s08_exit(void)
  {

  	mcp23s08_spi_exit();

  	mcp23s08_i2c_exit();

  }
  module_exit(mcp23s08_exit);
  
  MODULE_LICENSE("GPL");