/*
   * Driver for keys on TCA6416 I2C IO expander
   *
   * Copyright (C) 2010 Texas Instruments
   *
   * Author : Sriramakrishnan.A.G. <srk@ti.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/types.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  #include <linux/workqueue.h>
  #include <linux/gpio.h>
  #include <linux/i2c.h>
  #include <linux/input.h>
  #include <linux/tca6416_keypad.h>
  
  #define TCA6416_INPUT          0
  #define TCA6416_OUTPUT         1
  #define TCA6416_INVERT         2
  #define TCA6416_DIRECTION      3
  
  static const struct i2c_device_id tca6416_id[] = {
  	{ "tca6416-keys", 16, },
  	{ "tca6408-keys", 8, },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, tca6416_id);
  
  struct tca6416_drv_data {
  	struct input_dev *input;
  	struct tca6416_button data[0];
  };
  
  struct tca6416_keypad_chip {
  	uint16_t reg_output;
  	uint16_t reg_direction;
  	uint16_t reg_input;
  
  	struct i2c_client *client;
  	struct input_dev *input;
  	struct delayed_work dwork;
  	int io_size;
  	int irqnum;
  	u16 pinmask;
  	bool use_polling;
  	struct tca6416_button buttons[0];
  };
  
  static int tca6416_write_reg(struct tca6416_keypad_chip *chip, int reg, u16 val)
  {
  	int error;
  
  	error = chip->io_size > 8 ?
  		i2c_smbus_write_word_data(chip->client, reg << 1, val) :
  		i2c_smbus_write_byte_data(chip->client, reg, val);
  	if (error < 0) {
  		dev_err(&chip->client->dev,
  			"%s failed, reg: %d, val: %d, error: %d
  ",
  			__func__, reg, val, error);
  		return error;
  	}
  
  	return 0;
  }
  
  static int tca6416_read_reg(struct tca6416_keypad_chip *chip, int reg, u16 *val)
  {
  	int retval;
  
  	retval = chip->io_size > 8 ?
  		 i2c_smbus_read_word_data(chip->client, reg << 1) :
  		 i2c_smbus_read_byte_data(chip->client, reg);
  	if (retval < 0) {
  		dev_err(&chip->client->dev, "%s failed, reg: %d, error: %d
  ",
  			__func__, reg, retval);
  		return retval;
  	}
  
  	*val = (u16)retval;
  	return 0;
  }
  
  static void tca6416_keys_scan(struct tca6416_keypad_chip *chip)
  {
  	struct input_dev *input = chip->input;
  	u16 reg_val, val;
  	int error, i, pin_index;
  
  	error = tca6416_read_reg(chip, TCA6416_INPUT, &reg_val);
  	if (error)
  		return;
  
  	reg_val &= chip->pinmask;
  
  	/* Figure out which lines have changed */
  	val = reg_val ^ chip->reg_input;
  	chip->reg_input = reg_val;
  
  	for (i = 0, pin_index = 0; i < 16; i++) {
  		if (val & (1 << i)) {
  			struct tca6416_button *button = &chip->buttons[pin_index];
  			unsigned int type = button->type ?: EV_KEY;
  			int state = ((reg_val & (1 << i)) ? 1 : 0)
  						^ button->active_low;
  
  			input_event(input, type, button->code, !!state);
  			input_sync(input);
  		}
  
  		if (chip->pinmask & (1 << i))
  			pin_index++;
  	}
  }
  
  /*
   * This is threaded IRQ handler and this can (and will) sleep.
   */
  static irqreturn_t tca6416_keys_isr(int irq, void *dev_id)
  {
  	struct tca6416_keypad_chip *chip = dev_id;
  
  	tca6416_keys_scan(chip);
  
  	return IRQ_HANDLED;
  }
  
  static void tca6416_keys_work_func(struct work_struct *work)
  {
  	struct tca6416_keypad_chip *chip =
  		container_of(work, struct tca6416_keypad_chip, dwork.work);
  
  	tca6416_keys_scan(chip);
  	schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
  }
  
  static int tca6416_keys_open(struct input_dev *dev)
  {
  	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
  
  	/* Get initial device state in case it has switches */
  	tca6416_keys_scan(chip);
  
  	if (chip->use_polling)
  		schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
  	else
  		enable_irq(chip->irqnum);
  
  	return 0;
  }
  
  static void tca6416_keys_close(struct input_dev *dev)
  {
  	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
  
  	if (chip->use_polling)
  		cancel_delayed_work_sync(&chip->dwork);
  	else
  		disable_irq(chip->irqnum);
  }
  
  static int tca6416_setup_registers(struct tca6416_keypad_chip *chip)
  {
  	int error;
  
  	error = tca6416_read_reg(chip, TCA6416_OUTPUT, &chip->reg_output);
  	if (error)
  		return error;
  
  	error = tca6416_read_reg(chip, TCA6416_DIRECTION, &chip->reg_direction);
  	if (error)
  		return error;
  
  	/* ensure that keypad pins are set to input */
  	error = tca6416_write_reg(chip, TCA6416_DIRECTION,
  				  chip->reg_direction | chip->pinmask);
  	if (error)
  		return error;
  
  	error = tca6416_read_reg(chip, TCA6416_DIRECTION, &chip->reg_direction);
  	if (error)
  		return error;
  
  	error = tca6416_read_reg(chip, TCA6416_INPUT, &chip->reg_input);
  	if (error)
  		return error;
  
  	chip->reg_input &= chip->pinmask;
  
  	return 0;
  }
  
  static int tca6416_keypad_probe(struct i2c_client *client,
  				   const struct i2c_device_id *id)
  {
  	struct tca6416_keys_platform_data *pdata;
  	struct tca6416_keypad_chip *chip;
  	struct input_dev *input;
  	int error;
  	int i;
  
  	/* Check functionality */
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
  		dev_err(&client->dev, "%s adapter not supported
  ",
  			dev_driver_string(&client->adapter->dev));
  		return -ENODEV;
  	}
  
  	pdata = dev_get_platdata(&client->dev);
  	if (!pdata) {
  		dev_dbg(&client->dev, "no platform data
  ");
  		return -EINVAL;
  	}
  
  	chip = kzalloc(sizeof(struct tca6416_keypad_chip) +
  		       pdata->nbuttons * sizeof(struct tca6416_button),
  		       GFP_KERNEL);
  	input = input_allocate_device();
  	if (!chip || !input) {
  		error = -ENOMEM;
  		goto fail1;
  	}
  
  	chip->client = client;
  	chip->input = input;
  	chip->io_size = id->driver_data;
  	chip->pinmask = pdata->pinmask;
  	chip->use_polling = pdata->use_polling;
  
  	INIT_DELAYED_WORK(&chip->dwork, tca6416_keys_work_func);
  
  	input->phys = "tca6416-keys/input0";
  	input->name = client->name;
  	input->dev.parent = &client->dev;
  
  	input->open = tca6416_keys_open;
  	input->close = tca6416_keys_close;
  
  	input->id.bustype = BUS_HOST;
  	input->id.vendor = 0x0001;
  	input->id.product = 0x0001;
  	input->id.version = 0x0100;
  
  	/* Enable auto repeat feature of Linux input subsystem */
  	if (pdata->rep)
  		__set_bit(EV_REP, input->evbit);
  
  	for (i = 0; i < pdata->nbuttons; i++) {
  		unsigned int type;
  
  		chip->buttons[i] = pdata->buttons[i];
  		type = (pdata->buttons[i].type) ?: EV_KEY;
  		input_set_capability(input, type, pdata->buttons[i].code);
  	}
  
  	input_set_drvdata(input, chip);
  
  	/*
  	 * Initialize cached registers from their original values.
  	 * we can't share this chip with another i2c master.
  	 */
  	error = tca6416_setup_registers(chip);
  	if (error)
  		goto fail1;
  
  	if (!chip->use_polling) {
  		if (pdata->irq_is_gpio)
  			chip->irqnum = gpio_to_irq(client->irq);
  		else
  			chip->irqnum = client->irq;
  
  		error = request_threaded_irq(chip->irqnum, NULL,
  					     tca6416_keys_isr,
  					     IRQF_TRIGGER_FALLING |
  						IRQF_ONESHOT,
  					     "tca6416-keypad", chip);
  		if (error) {
  			dev_dbg(&client->dev,
  				"Unable to claim irq %d; error %d
  ",
  				chip->irqnum, error);
  			goto fail1;
  		}
  		disable_irq(chip->irqnum);
  	}
  
  	error = input_register_device(input);
  	if (error) {
  		dev_dbg(&client->dev,
  			"Unable to register input device, error: %d
  ", error);
  		goto fail2;
  	}
  
  	i2c_set_clientdata(client, chip);
  	device_init_wakeup(&client->dev, 1);
  
  	return 0;
  
  fail2:
  	if (!chip->use_polling) {
  		free_irq(chip->irqnum, chip);
  		enable_irq(chip->irqnum);
  	}
  fail1:
  	input_free_device(input);
  	kfree(chip);
  	return error;
  }
  
  static int tca6416_keypad_remove(struct i2c_client *client)
  {
  	struct tca6416_keypad_chip *chip = i2c_get_clientdata(client);
  
  	if (!chip->use_polling) {
  		free_irq(chip->irqnum, chip);
  		enable_irq(chip->irqnum);
  	}
  
  	input_unregister_device(chip->input);
  	kfree(chip);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int tca6416_keypad_suspend(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tca6416_keypad_chip *chip = i2c_get_clientdata(client);
  
  	if (device_may_wakeup(dev))
  		enable_irq_wake(chip->irqnum);
  
  	return 0;
  }
  
  static int tca6416_keypad_resume(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tca6416_keypad_chip *chip = i2c_get_clientdata(client);
  
  	if (device_may_wakeup(dev))
  		disable_irq_wake(chip->irqnum);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(tca6416_keypad_dev_pm_ops,
  			 tca6416_keypad_suspend, tca6416_keypad_resume);
  
  static struct i2c_driver tca6416_keypad_driver = {
  	.driver = {
  		.name	= "tca6416-keypad",
  		.pm	= &tca6416_keypad_dev_pm_ops,
  	},
  	.probe		= tca6416_keypad_probe,
  	.remove		= tca6416_keypad_remove,
  	.id_table	= tca6416_id,
  };
  
  static int __init tca6416_keypad_init(void)
  {
  	return i2c_add_driver(&tca6416_keypad_driver);
  }
  
  subsys_initcall(tca6416_keypad_init);
  
  static void __exit tca6416_keypad_exit(void)
  {
  	i2c_del_driver(&tca6416_keypad_driver);
  }
  module_exit(tca6416_keypad_exit);
  
  MODULE_AUTHOR("Sriramakrishnan <srk@ti.com>");
  MODULE_DESCRIPTION("Keypad driver over tca6146 IO expander");
  MODULE_LICENSE("GPL");