/*

   *  MAX732x I2C Port Expander with 8/16 I/O

   *
   *  Copyright (C) 2007 Marvell International Ltd.
   *  Copyright (C) 2008 Jack Ren <jack.ren@marvell.com>
   *  Copyright (C) 2008 Eric Miao <eric.miao@marvell.com>
   *
   *  Derived from drivers/gpio/pca953x.c
   *
   *  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; version 2 of the License.
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/gpio.h>

  #include <linux/interrupt.h>
  #include <linux/irq.h>

  #include <linux/i2c.h>
  #include <linux/i2c/max732x.h>
  
  
  /*
   * Each port of MAX732x (including MAX7319) falls into one of the
   * following three types:
   *
   *   - Push Pull Output
   *   - Input
   *   - Open Drain I/O
   *
   * designated by 'O', 'I' and 'P' individually according to MAXIM's

   * datasheets. 'I' and 'P' ports are interrupt capables, some with
   * a dedicated interrupt mask.

   *
   * There are two groups of I/O ports, each group usually includes
   * up to 8 I/O ports, and is accessed by a specific I2C address:
   *
   *   - Group A : by I2C address 0b'110xxxx
   *   - Group B : by I2C address 0b'101xxxx
   *
   * where 'xxxx' is decided by the connections of pin AD2/AD0.  The
   * address used also affects the initial state of output signals.
   *
   * Within each group of ports, there are five known combinations of
   * I/O ports: 4I4O, 4P4O, 8I, 8P, 8O, see the definitions below for

   * the detailed organization of these ports. Only Goup A is interrupt
   * capable.

   *
   * GPIO numbers start from 'gpio_base + 0' to 'gpio_base + 8/16',
   * and GPIOs from GROUP_A are numbered before those from GROUP_B
   * (if there are two groups).
   *
   * NOTE: MAX7328/MAX7329 are drop-in replacements for PCF8574/a, so
   * they are not supported by this driver.
   */
  
  #define PORT_NONE	0x0	/* '/' No Port */
  #define PORT_OUTPUT	0x1	/* 'O' Push-Pull, Output Only */
  #define PORT_INPUT	0x2	/* 'I' Input Only */
  #define PORT_OPENDRAIN	0x3	/* 'P' Open-Drain, I/O */
  
  #define IO_4I4O		0x5AA5	/* O7 O6 I5 I4 I3 I2 O1 O0 */
  #define IO_4P4O		0x5FF5	/* O7 O6 P5 P4 P3 P2 O1 O0 */
  #define IO_8I		0xAAAA	/* I7 I6 I5 I4 I3 I2 I1 I0 */
  #define IO_8P		0xFFFF	/* P7 P6 P5 P4 P3 P2 P1 P0 */
  #define IO_8O		0x5555	/* O7 O6 O5 O4 O3 O2 O1 O0 */
  
  #define GROUP_A(x)	((x) & 0xffff)	/* I2C Addr: 0b'110xxxx */
  #define GROUP_B(x)	((x) << 16)	/* I2C Addr: 0b'101xxxx */

  #define INT_NONE	0x0	/* No interrupt capability */
  #define INT_NO_MASK	0x1	/* Has interrupts, no mask */
  #define INT_INDEP_MASK	0x2	/* Has interrupts, independent mask */
  #define INT_MERGED_MASK 0x3	/* Has interrupts, merged mask */
  
  #define INT_CAPS(x)	(((uint64_t)(x)) << 32)
  
  enum {
  	MAX7319,
  	MAX7320,
  	MAX7321,
  	MAX7322,
  	MAX7323,
  	MAX7324,
  	MAX7325,
  	MAX7326,
  	MAX7327,
  };
  
  static uint64_t max732x_features[] = {
  	[MAX7319] = GROUP_A(IO_8I) | INT_CAPS(INT_MERGED_MASK),
  	[MAX7320] = GROUP_B(IO_8O),
  	[MAX7321] = GROUP_A(IO_8P) | INT_CAPS(INT_NO_MASK),
  	[MAX7322] = GROUP_A(IO_4I4O) | INT_CAPS(INT_MERGED_MASK),
  	[MAX7323] = GROUP_A(IO_4P4O) | INT_CAPS(INT_INDEP_MASK),
  	[MAX7324] = GROUP_A(IO_8I) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
  	[MAX7325] = GROUP_A(IO_8P) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
  	[MAX7326] = GROUP_A(IO_4I4O) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
  	[MAX7327] = GROUP_A(IO_4P4O) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
  };

  static const struct i2c_device_id max732x_id[] = {

  	{ "max7319", MAX7319 },
  	{ "max7320", MAX7320 },
  	{ "max7321", MAX7321 },
  	{ "max7322", MAX7322 },
  	{ "max7323", MAX7323 },
  	{ "max7324", MAX7324 },
  	{ "max7325", MAX7325 },
  	{ "max7326", MAX7326 },
  	{ "max7327", MAX7327 },

  	{ },
  };
  MODULE_DEVICE_TABLE(i2c, max732x_id);
  
  struct max732x_chip {
  	struct gpio_chip gpio_chip;
  
  	struct i2c_client *client;	/* "main" client */
  	struct i2c_client *client_dummy;
  	struct i2c_client *client_group_a;
  	struct i2c_client *client_group_b;
  
  	unsigned int	mask_group_a;
  	unsigned int	dir_input;
  	unsigned int	dir_output;
  
  	struct mutex	lock;
  	uint8_t		reg_out[2];

  
  #ifdef CONFIG_GPIO_MAX732X_IRQ
  	struct mutex	irq_lock;
  	int		irq_base;
  	uint8_t		irq_mask;
  	uint8_t		irq_mask_cur;
  	uint8_t		irq_trig_raise;
  	uint8_t		irq_trig_fall;
  	uint8_t		irq_features;
  #endif

  };

  static int max732x_writeb(struct max732x_chip *chip, int group_a, uint8_t val)

  {
  	struct i2c_client *client;
  	int ret;
  
  	client = group_a ? chip->client_group_a : chip->client_group_b;
  	ret = i2c_smbus_write_byte(client, val);
  	if (ret < 0) {
  		dev_err(&client->dev, "failed writing
  ");
  		return ret;
  	}
  
  	return 0;
  }

  static int max732x_readb(struct max732x_chip *chip, int group_a, uint8_t *val)

  {
  	struct i2c_client *client;
  	int ret;
  
  	client = group_a ? chip->client_group_a : chip->client_group_b;
  	ret = i2c_smbus_read_byte(client);
  	if (ret < 0) {
  		dev_err(&client->dev, "failed reading
  ");
  		return ret;
  	}
  
  	*val = (uint8_t)ret;
  	return 0;
  }
  
  static inline int is_group_a(struct max732x_chip *chip, unsigned off)
  {
  	return (1u << off) & chip->mask_group_a;
  }
  
  static int max732x_gpio_get_value(struct gpio_chip *gc, unsigned off)
  {
  	struct max732x_chip *chip;
  	uint8_t reg_val;
  	int ret;
  
  	chip = container_of(gc, struct max732x_chip, gpio_chip);

  	ret = max732x_readb(chip, is_group_a(chip, off), &reg_val);

  	if (ret < 0)
  		return 0;
  
  	return reg_val & (1u << (off & 0x7));
  }
  
  static void max732x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
  {
  	struct max732x_chip *chip;
  	uint8_t reg_out, mask = 1u << (off & 0x7);
  	int ret;
  
  	chip = container_of(gc, struct max732x_chip, gpio_chip);
  
  	mutex_lock(&chip->lock);
  
  	reg_out = (off > 7) ? chip->reg_out[1] : chip->reg_out[0];
  	reg_out = (val) ? reg_out | mask : reg_out & ~mask;

  	ret = max732x_writeb(chip, is_group_a(chip, off), reg_out);

  	if (ret < 0)
  		goto out;
  
  	/* update the shadow register then */
  	if (off > 7)
  		chip->reg_out[1] = reg_out;
  	else
  		chip->reg_out[0] = reg_out;
  out:
  	mutex_unlock(&chip->lock);
  }
  
  static int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
  {
  	struct max732x_chip *chip;
  	unsigned int mask = 1u << off;
  
  	chip = container_of(gc, struct max732x_chip, gpio_chip);
  
  	if ((mask & chip->dir_input) == 0) {
  		dev_dbg(&chip->client->dev, "%s port %d is output only
  ",
  			chip->client->name, off);
  		return -EACCES;
  	}

  	/*
  	 * Open-drain pins must be set to high impedance (which is
  	 * equivalent to output-high) to be turned into an input.
  	 */
  	if ((mask & chip->dir_output))
  		max732x_gpio_set_value(gc, off, 1);

  	return 0;
  }
  
  static int max732x_gpio_direction_output(struct gpio_chip *gc,
  		unsigned off, int val)
  {
  	struct max732x_chip *chip;
  	unsigned int mask = 1u << off;
  
  	chip = container_of(gc, struct max732x_chip, gpio_chip);
  
  	if ((mask & chip->dir_output) == 0) {
  		dev_dbg(&chip->client->dev, "%s port %d is input only
  ",
  			chip->client->name, off);
  		return -EACCES;
  	}
  
  	max732x_gpio_set_value(gc, off, val);
  	return 0;
  }

  #ifdef CONFIG_GPIO_MAX732X_IRQ
  static int max732x_writew(struct max732x_chip *chip, uint16_t val)
  {
  	int ret;
  
  	val = cpu_to_le16(val);
  
  	ret = i2c_master_send(chip->client_group_a, (char *)&val, 2);
  	if (ret < 0) {
  		dev_err(&chip->client_group_a->dev, "failed writing
  ");
  		return ret;
  	}
  
  	return 0;
  }
  
  static int max732x_readw(struct max732x_chip *chip, uint16_t *val)
  {
  	int ret;
  
  	ret = i2c_master_recv(chip->client_group_a, (char *)val, 2);
  	if (ret < 0) {
  		dev_err(&chip->client_group_a->dev, "failed reading
  ");
  		return ret;
  	}
  
  	*val = le16_to_cpu(*val);
  	return 0;
  }
  
  static void max732x_irq_update_mask(struct max732x_chip *chip)
  {
  	uint16_t msg;
  
  	if (chip->irq_mask == chip->irq_mask_cur)
  		return;
  
  	chip->irq_mask = chip->irq_mask_cur;
  
  	if (chip->irq_features == INT_NO_MASK)
  		return;
  
  	mutex_lock(&chip->lock);
  
  	switch (chip->irq_features) {
  	case INT_INDEP_MASK:
  		msg = (chip->irq_mask << 8) | chip->reg_out[0];
  		max732x_writew(chip, msg);
  		break;
  
  	case INT_MERGED_MASK:
  		msg = chip->irq_mask | chip->reg_out[0];
  		max732x_writeb(chip, 1, (uint8_t)msg);
  		break;
  	}
  
  	mutex_unlock(&chip->lock);
  }
  
  static int max732x_gpio_to_irq(struct gpio_chip *gc, unsigned off)
  {
  	struct max732x_chip *chip;
  
  	chip = container_of(gc, struct max732x_chip, gpio_chip);
  	return chip->irq_base + off;
  }

  static void max732x_irq_mask(struct irq_data *d)

  {

  	struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

  	chip->irq_mask_cur &= ~(1 << (d->irq - chip->irq_base));

  }

  static void max732x_irq_unmask(struct irq_data *d)

  {

  	struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

  	chip->irq_mask_cur |= 1 << (d->irq - chip->irq_base);

  }

  static void max732x_irq_bus_lock(struct irq_data *d)

  {

  	struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

  
  	mutex_lock(&chip->irq_lock);
  	chip->irq_mask_cur = chip->irq_mask;
  }

  static void max732x_irq_bus_sync_unlock(struct irq_data *d)

  {

  	struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

  
  	max732x_irq_update_mask(chip);
  	mutex_unlock(&chip->irq_lock);
  }

  static int max732x_irq_set_type(struct irq_data *d, unsigned int type)

  {

  	struct max732x_chip *chip = irq_data_get_irq_chip_data(d);
  	uint16_t off = d->irq - chip->irq_base;

  	uint16_t mask = 1 << off;
  
  	if (!(mask & chip->dir_input)) {
  		dev_dbg(&chip->client->dev, "%s port %d is output only
  ",
  			chip->client->name, off);
  		return -EACCES;
  	}
  
  	if (!(type & IRQ_TYPE_EDGE_BOTH)) {
  		dev_err(&chip->client->dev, "irq %d: unsupported type %d
  ",

  			d->irq, type);

  		return -EINVAL;
  	}
  
  	if (type & IRQ_TYPE_EDGE_FALLING)
  		chip->irq_trig_fall |= mask;
  	else
  		chip->irq_trig_fall &= ~mask;
  
  	if (type & IRQ_TYPE_EDGE_RISING)
  		chip->irq_trig_raise |= mask;
  	else
  		chip->irq_trig_raise &= ~mask;
  
  	return max732x_gpio_direction_input(&chip->gpio_chip, off);
  }
  
  static struct irq_chip max732x_irq_chip = {
  	.name			= "max732x",

  	.irq_mask		= max732x_irq_mask,
  	.irq_unmask		= max732x_irq_unmask,
  	.irq_bus_lock		= max732x_irq_bus_lock,
  	.irq_bus_sync_unlock	= max732x_irq_bus_sync_unlock,
  	.irq_set_type		= max732x_irq_set_type,

  };
  
  static uint8_t max732x_irq_pending(struct max732x_chip *chip)
  {
  	uint8_t cur_stat;
  	uint8_t old_stat;
  	uint8_t trigger;
  	uint8_t pending;
  	uint16_t status;
  	int ret;
  
  	ret = max732x_readw(chip, &status);
  	if (ret)
  		return 0;
  
  	trigger = status >> 8;
  	trigger &= chip->irq_mask;
  
  	if (!trigger)
  		return 0;
  
  	cur_stat = status & 0xFF;
  	cur_stat &= chip->irq_mask;
  
  	old_stat = cur_stat ^ trigger;
  
  	pending = (old_stat & chip->irq_trig_fall) |
  		  (cur_stat & chip->irq_trig_raise);
  	pending &= trigger;
  
  	return pending;
  }
  
  static irqreturn_t max732x_irq_handler(int irq, void *devid)
  {
  	struct max732x_chip *chip = devid;
  	uint8_t pending;
  	uint8_t level;
  
  	pending = max732x_irq_pending(chip);
  
  	if (!pending)
  		return IRQ_HANDLED;
  
  	do {
  		level = __ffs(pending);
  		handle_nested_irq(level + chip->irq_base);
  
  		pending &= ~(1 << level);
  	} while (pending);
  
  	return IRQ_HANDLED;
  }
  
  static int max732x_irq_setup(struct max732x_chip *chip,
  			     const struct i2c_device_id *id)
  {
  	struct i2c_client *client = chip->client;
  	struct max732x_platform_data *pdata = client->dev.platform_data;
  	int has_irq = max732x_features[id->driver_data] >> 32;
  	int ret;
  
  	if (pdata->irq_base && has_irq != INT_NONE) {
  		int lvl;
  
  		chip->irq_base = pdata->irq_base;
  		chip->irq_features = has_irq;
  		mutex_init(&chip->irq_lock);
  
  		for (lvl = 0; lvl < chip->gpio_chip.ngpio; lvl++) {
  			int irq = lvl + chip->irq_base;
  
  			if (!(chip->dir_input & (1 << lvl)))
  				continue;

  			irq_set_chip_data(irq, chip);
  			irq_set_chip_and_handler(irq, &max732x_irq_chip,

  						 handle_edge_irq);

  			irq_set_nested_thread(irq, 1);

  #ifdef CONFIG_ARM
  			set_irq_flags(irq, IRQF_VALID);
  #else

  			irq_set_noprobe(irq);

  #endif
  		}
  
  		ret = request_threaded_irq(client->irq,
  					   NULL,
  					   max732x_irq_handler,
  					   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
  					   dev_name(&client->dev), chip);
  		if (ret) {
  			dev_err(&client->dev, "failed to request irq %d
  ",
  				client->irq);
  			goto out_failed;
  		}
  
  		chip->gpio_chip.to_irq = max732x_gpio_to_irq;
  	}
  
  	return 0;
  
  out_failed:
  	chip->irq_base = 0;
  	return ret;
  }
  
  static void max732x_irq_teardown(struct max732x_chip *chip)
  {
  	if (chip->irq_base)
  		free_irq(chip->client->irq, chip);
  }
  #else /* CONFIG_GPIO_MAX732X_IRQ */
  static int max732x_irq_setup(struct max732x_chip *chip,
  			     const struct i2c_device_id *id)
  {
  	struct i2c_client *client = chip->client;
  	struct max732x_platform_data *pdata = client->dev.platform_data;
  	int has_irq = max732x_features[id->driver_data] >> 32;
  
  	if (pdata->irq_base && has_irq != INT_NONE)
  		dev_warn(&client->dev, "interrupt support not compiled in
  ");
  
  	return 0;
  }
  
  static void max732x_irq_teardown(struct max732x_chip *chip)
  {
  }
  #endif

  static int __devinit max732x_setup_gpio(struct max732x_chip *chip,
  					const struct i2c_device_id *id,
  					unsigned gpio_start)
  {
  	struct gpio_chip *gc = &chip->gpio_chip;

  	uint32_t id_data = (uint32_t)max732x_features[id->driver_data];

  	int i, port = 0;
  
  	for (i = 0; i < 16; i++, id_data >>= 2) {
  		unsigned int mask = 1 << port;
  
  		switch (id_data & 0x3) {
  		case PORT_OUTPUT:
  			chip->dir_output |= mask;
  			break;
  		case PORT_INPUT:
  			chip->dir_input |= mask;
  			break;
  		case PORT_OPENDRAIN:
  			chip->dir_output |= mask;
  			chip->dir_input |= mask;
  			break;
  		default:
  			continue;
  		}
  
  		if (i < 8)
  			chip->mask_group_a |= mask;
  		port++;
  	}
  
  	if (chip->dir_input)
  		gc->direction_input = max732x_gpio_direction_input;
  	if (chip->dir_output) {
  		gc->direction_output = max732x_gpio_direction_output;
  		gc->set = max732x_gpio_set_value;
  	}
  	gc->get = max732x_gpio_get_value;
  	gc->can_sleep = 1;
  
  	gc->base = gpio_start;
  	gc->ngpio = port;
  	gc->label = chip->client->name;
  	gc->owner = THIS_MODULE;
  
  	return port;
  }
  
  static int __devinit max732x_probe(struct i2c_client *client,
  				   const struct i2c_device_id *id)
  {
  	struct max732x_platform_data *pdata;
  	struct max732x_chip *chip;
  	struct i2c_client *c;
  	uint16_t addr_a, addr_b;
  	int ret, nr_port;
  
  	pdata = client->dev.platform_data;

  	if (pdata == NULL) {
  		dev_dbg(&client->dev, "no platform data
  ");
  		return -EINVAL;
  	}

  
  	chip = kzalloc(sizeof(struct max732x_chip), GFP_KERNEL);
  	if (chip == NULL)
  		return -ENOMEM;
  	chip->client = client;
  
  	nr_port = max732x_setup_gpio(chip, id, pdata->gpio_base);
  
  	addr_a = (client->addr & 0x0f) | 0x60;
  	addr_b = (client->addr & 0x0f) | 0x50;
  
  	switch (client->addr & 0x70) {
  	case 0x60:
  		chip->client_group_a = client;

  		if (nr_port > 8) {

  			c = i2c_new_dummy(client->adapter, addr_b);
  			chip->client_group_b = chip->client_dummy = c;
  		}
  		break;
  	case 0x50:
  		chip->client_group_b = client;

  		if (nr_port > 8) {

  			c = i2c_new_dummy(client->adapter, addr_a);
  			chip->client_group_a = chip->client_dummy = c;
  		}
  		break;
  	default:
  		dev_err(&client->dev, "invalid I2C address specified %02x
  ",
  				client->addr);
  		ret = -EINVAL;
  		goto out_failed;
  	}
  
  	mutex_init(&chip->lock);

  	max732x_readb(chip, is_group_a(chip, 0), &chip->reg_out[0]);

  	if (nr_port > 8)

  		max732x_readb(chip, is_group_a(chip, 8), &chip->reg_out[1]);
  
  	ret = max732x_irq_setup(chip, id);
  	if (ret)
  		goto out_failed;

  
  	ret = gpiochip_add(&chip->gpio_chip);
  	if (ret)
  		goto out_failed;
  
  	if (pdata->setup) {
  		ret = pdata->setup(client, chip->gpio_chip.base,
  				chip->gpio_chip.ngpio, pdata->context);
  		if (ret < 0)
  			dev_warn(&client->dev, "setup failed, %d
  ", ret);
  	}
  
  	i2c_set_clientdata(client, chip);
  	return 0;
  
  out_failed:

  	max732x_irq_teardown(chip);

  	kfree(chip);
  	return ret;
  }
  
  static int __devexit max732x_remove(struct i2c_client *client)
  {
  	struct max732x_platform_data *pdata = client->dev.platform_data;
  	struct max732x_chip *chip = i2c_get_clientdata(client);
  	int ret;
  
  	if (pdata->teardown) {
  		ret = pdata->teardown(client, chip->gpio_chip.base,
  				chip->gpio_chip.ngpio, pdata->context);
  		if (ret < 0) {
  			dev_err(&client->dev, "%s failed, %d
  ",
  					"teardown", ret);
  			return ret;
  		}
  	}
  
  	ret = gpiochip_remove(&chip->gpio_chip);
  	if (ret) {
  		dev_err(&client->dev, "%s failed, %d
  ",
  				"gpiochip_remove()", ret);
  		return ret;
  	}

  	max732x_irq_teardown(chip);

  	/* unregister any dummy i2c_client */
  	if (chip->client_dummy)
  		i2c_unregister_device(chip->client_dummy);
  
  	kfree(chip);
  	return 0;
  }
  
  static struct i2c_driver max732x_driver = {
  	.driver = {
  		.name	= "max732x",
  		.owner	= THIS_MODULE,
  	},
  	.probe		= max732x_probe,
  	.remove		= __devexit_p(max732x_remove),
  	.id_table	= max732x_id,
  };
  
  static int __init max732x_init(void)
  {
  	return i2c_add_driver(&max732x_driver);
  }

  /* register after i2c postcore initcall and before
   * subsys initcalls that may rely on these GPIOs
   */
  subsys_initcall(max732x_init);

  
  static void __exit max732x_exit(void)
  {
  	i2c_del_driver(&max732x_driver);
  }
  module_exit(max732x_exit);
  
  MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
  MODULE_DESCRIPTION("GPIO expander driver for MAX732X");
  MODULE_LICENSE("GPL");