/*
   * Driver for TCA8418 I2C keyboard
   *
   * Copyright (C) 2011 Fuel7, Inc.  All rights reserved.
   *
   * Author: Kyle Manna <kyle.manna@fuel7.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * 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., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   *
   * If you can't comply with GPLv2, alternative licensing terms may be
   * arranged. Please contact Fuel7, Inc. (http://fuel7.com/) for proprietary
   * alternative licensing inquiries.
   */
  
  #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/input/tca8418_keypad.h>
  #include <linux/of.h>
  
  /* TCA8418 hardware limits */
  #define TCA8418_MAX_ROWS	8
  #define TCA8418_MAX_COLS	10
  
  /* TCA8418 register offsets */
  #define REG_CFG			0x01
  #define REG_INT_STAT		0x02
  #define REG_KEY_LCK_EC		0x03
  #define REG_KEY_EVENT_A		0x04
  #define REG_KEY_EVENT_B		0x05
  #define REG_KEY_EVENT_C		0x06
  #define REG_KEY_EVENT_D		0x07
  #define REG_KEY_EVENT_E		0x08
  #define REG_KEY_EVENT_F		0x09
  #define REG_KEY_EVENT_G		0x0A
  #define REG_KEY_EVENT_H		0x0B
  #define REG_KEY_EVENT_I		0x0C
  #define REG_KEY_EVENT_J		0x0D
  #define REG_KP_LCK_TIMER	0x0E
  #define REG_UNLOCK1		0x0F
  #define REG_UNLOCK2		0x10
  #define REG_GPIO_INT_STAT1	0x11
  #define REG_GPIO_INT_STAT2	0x12
  #define REG_GPIO_INT_STAT3	0x13
  #define REG_GPIO_DAT_STAT1	0x14
  #define REG_GPIO_DAT_STAT2	0x15
  #define REG_GPIO_DAT_STAT3	0x16
  #define REG_GPIO_DAT_OUT1	0x17
  #define REG_GPIO_DAT_OUT2	0x18
  #define REG_GPIO_DAT_OUT3	0x19
  #define REG_GPIO_INT_EN1	0x1A
  #define REG_GPIO_INT_EN2	0x1B
  #define REG_GPIO_INT_EN3	0x1C
  #define REG_KP_GPIO1		0x1D
  #define REG_KP_GPIO2		0x1E
  #define REG_KP_GPIO3		0x1F
  #define REG_GPI_EM1		0x20
  #define REG_GPI_EM2		0x21
  #define REG_GPI_EM3		0x22
  #define REG_GPIO_DIR1		0x23
  #define REG_GPIO_DIR2		0x24
  #define REG_GPIO_DIR3		0x25
  #define REG_GPIO_INT_LVL1	0x26
  #define REG_GPIO_INT_LVL2	0x27
  #define REG_GPIO_INT_LVL3	0x28
  #define REG_DEBOUNCE_DIS1	0x29
  #define REG_DEBOUNCE_DIS2	0x2A
  #define REG_DEBOUNCE_DIS3	0x2B
  #define REG_GPIO_PULL1		0x2C
  #define REG_GPIO_PULL2		0x2D
  #define REG_GPIO_PULL3		0x2E
  
  /* TCA8418 bit definitions */
  #define CFG_AI			BIT(7)
  #define CFG_GPI_E_CFG		BIT(6)
  #define CFG_OVR_FLOW_M		BIT(5)
  #define CFG_INT_CFG		BIT(4)
  #define CFG_OVR_FLOW_IEN	BIT(3)
  #define CFG_K_LCK_IEN		BIT(2)
  #define CFG_GPI_IEN		BIT(1)
  #define CFG_KE_IEN		BIT(0)
  
  #define INT_STAT_CAD_INT	BIT(4)
  #define INT_STAT_OVR_FLOW_INT	BIT(3)
  #define INT_STAT_K_LCK_INT	BIT(2)
  #define INT_STAT_GPI_INT	BIT(1)
  #define INT_STAT_K_INT		BIT(0)
  
  /* TCA8418 register masks */
  #define KEY_LCK_EC_KEC		0x7
  #define KEY_EVENT_CODE		0x7f
  #define KEY_EVENT_VALUE		0x80
  
  struct tca8418_keypad {
  	struct i2c_client *client;
  	struct input_dev *input;
  
  	unsigned int row_shift;
  };
  
  /*
   * Write a byte to the TCA8418
   */
  static int tca8418_write_byte(struct tca8418_keypad *keypad_data,
  			      int reg, u8 val)
  {
  	int error;
  
  	error = i2c_smbus_write_byte_data(keypad_data->client, reg, val);
  	if (error < 0) {
  		dev_err(&keypad_data->client->dev,
  			"%s failed, reg: %d, val: %d, error: %d
  ",
  			__func__, reg, val, error);
  		return error;
  	}
  
  	return 0;
  }
  
  /*
   * Read a byte from the TCA8418
   */
  static int tca8418_read_byte(struct tca8418_keypad *keypad_data,
  			     int reg, u8 *val)
  {
  	int error;
  
  	error = i2c_smbus_read_byte_data(keypad_data->client, reg);
  	if (error < 0) {
  		dev_err(&keypad_data->client->dev,
  				"%s failed, reg: %d, error: %d
  ",
  				__func__, reg, error);
  		return error;
  	}
  
  	*val = (u8)error;
  
  	return 0;
  }
  
  static void tca8418_read_keypad(struct tca8418_keypad *keypad_data)
  {
  	struct input_dev *input = keypad_data->input;
  	unsigned short *keymap = input->keycode;
  	int error, col, row;
  	u8 reg, state, code;
  
  	/* Initial read of the key event FIFO */
  	error = tca8418_read_byte(keypad_data, REG_KEY_EVENT_A, &reg);
  
  	/* Assume that key code 0 signifies empty FIFO */
  	while (error >= 0 && reg > 0) {
  		state = reg & KEY_EVENT_VALUE;
  		code  = reg & KEY_EVENT_CODE;
  
  		row = code / TCA8418_MAX_COLS;
  		col = code % TCA8418_MAX_COLS;
  
  		row = (col) ? row : row - 1;
  		col = (col) ? col - 1 : TCA8418_MAX_COLS - 1;
  
  		code = MATRIX_SCAN_CODE(row, col, keypad_data->row_shift);
  		input_event(input, EV_MSC, MSC_SCAN, code);
  		input_report_key(input, keymap[code], state);
  
  		/* Read for next loop */
  		error = tca8418_read_byte(keypad_data, REG_KEY_EVENT_A, &reg);
  	}
  
  	if (error < 0)
  		dev_err(&keypad_data->client->dev,
  			"unable to read REG_KEY_EVENT_A
  ");
  
  	input_sync(input);
  }
  
  /*
   * Threaded IRQ handler and this can (and will) sleep.
   */
  static irqreturn_t tca8418_irq_handler(int irq, void *dev_id)
  {
  	struct tca8418_keypad *keypad_data = dev_id;
  	u8 reg;
  	int error;
  
  	error = tca8418_read_byte(keypad_data, REG_INT_STAT, &reg);
  	if (error) {
  		dev_err(&keypad_data->client->dev,
  			"unable to read REG_INT_STAT
  ");
  		return IRQ_NONE;
  	}
  
  	if (!reg)
  		return IRQ_NONE;
  
  	if (reg & INT_STAT_OVR_FLOW_INT)
  		dev_warn(&keypad_data->client->dev, "overflow occurred
  ");
  
  	if (reg & INT_STAT_K_INT)
  		tca8418_read_keypad(keypad_data);
  
  	/* Clear all interrupts, even IRQs we didn't check (GPI, CAD, LCK) */
  	reg = 0xff;
  	error = tca8418_write_byte(keypad_data, REG_INT_STAT, reg);
  	if (error)
  		dev_err(&keypad_data->client->dev,
  			"unable to clear REG_INT_STAT
  ");
  
  	return IRQ_HANDLED;
  }
  
  /*
   * Configure the TCA8418 for keypad operation
   */
  static int tca8418_configure(struct tca8418_keypad *keypad_data,
  			     u32 rows, u32 cols)
  {
  	int reg, error;
  
  	/* Write config register, if this fails assume device not present */
  	error = tca8418_write_byte(keypad_data, REG_CFG,
  				CFG_INT_CFG | CFG_OVR_FLOW_IEN | CFG_KE_IEN);
  	if (error < 0)
  		return -ENODEV;
  
  
  	/* Assemble a mask for row and column registers */
  	reg  =  ~(~0 << rows);
  	reg += (~(~0 << cols)) << 8;
  
  	/* Set registers to keypad mode */
  	error |= tca8418_write_byte(keypad_data, REG_KP_GPIO1, reg);
  	error |= tca8418_write_byte(keypad_data, REG_KP_GPIO2, reg >> 8);
  	error |= tca8418_write_byte(keypad_data, REG_KP_GPIO3, reg >> 16);
  
  	/* Enable column debouncing */
  	error |= tca8418_write_byte(keypad_data, REG_DEBOUNCE_DIS1, reg);
  	error |= tca8418_write_byte(keypad_data, REG_DEBOUNCE_DIS2, reg >> 8);
  	error |= tca8418_write_byte(keypad_data, REG_DEBOUNCE_DIS3, reg >> 16);
  
  	return error;
  }
  
  static int tca8418_keypad_probe(struct i2c_client *client,
  					  const struct i2c_device_id *id)
  {
  	struct device *dev = &client->dev;
  	const struct tca8418_keypad_platform_data *pdata =
  						dev_get_platdata(dev);
  	struct tca8418_keypad *keypad_data;
  	struct input_dev *input;
  	const struct matrix_keymap_data *keymap_data = NULL;
  	u32 rows = 0, cols = 0;
  	bool rep = false;
  	bool irq_is_gpio = false;
  	int irq;
  	int error, row_shift, max_keys;
  
  	/* Copy the platform data */
  	if (pdata) {
  		if (!pdata->keymap_data) {
  			dev_err(dev, "no keymap data defined
  ");
  			return -EINVAL;
  		}
  		keymap_data = pdata->keymap_data;
  		rows = pdata->rows;
  		cols = pdata->cols;
  		rep  = pdata->rep;
  		irq_is_gpio = pdata->irq_is_gpio;
  	} else {
  		struct device_node *np = dev->of_node;
  		int err;
  
  		err = matrix_keypad_parse_of_params(dev, &rows, &cols);
  		if (err)
  			return err;
  		rep = of_property_read_bool(np, "keypad,autorepeat");
  	}
  
  	if (!rows || rows > TCA8418_MAX_ROWS) {
  		dev_err(dev, "invalid rows
  ");
  		return -EINVAL;
  	}
  
  	if (!cols || cols > TCA8418_MAX_COLS) {
  		dev_err(dev, "invalid columns
  ");
  		return -EINVAL;
  	}
  
  	/* Check i2c driver capabilities */
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
  		dev_err(dev, "%s adapter not supported
  ",
  			dev_driver_string(&client->adapter->dev));
  		return -ENODEV;
  	}
  
  	row_shift = get_count_order(cols);
  	max_keys = rows << row_shift;
  
  	/* Allocate memory for keypad_data and input device */
  	keypad_data = devm_kzalloc(dev, sizeof(*keypad_data), GFP_KERNEL);
  	if (!keypad_data)
  		return -ENOMEM;
  
  	keypad_data->client = client;
  	keypad_data->row_shift = row_shift;
  
  	/* Initialize the chip or fail if chip isn't present */
  	error = tca8418_configure(keypad_data, rows, cols);
  	if (error < 0)
  		return error;
  
  	/* Configure input device */
  	input = devm_input_allocate_device(dev);
  	if (!input)
  		return -ENOMEM;
  
  	keypad_data->input = input;
  
  	input->name = client->name;
  	input->id.bustype = BUS_I2C;
  	input->id.vendor  = 0x0001;
  	input->id.product = 0x001;
  	input->id.version = 0x0001;
  
  	error = matrix_keypad_build_keymap(keymap_data, NULL, rows, cols,
  					   NULL, input);
  	if (error) {
  		dev_err(dev, "Failed to build keymap
  ");
  		return error;
  	}
  
  	if (rep)
  		__set_bit(EV_REP, input->evbit);
  	input_set_capability(input, EV_MSC, MSC_SCAN);
  
  	input_set_drvdata(input, keypad_data);
  
  	irq = client->irq;
  	if (irq_is_gpio)
  		irq = gpio_to_irq(irq);
  
  	error = devm_request_threaded_irq(dev, irq, NULL, tca8418_irq_handler,
  					  IRQF_TRIGGER_FALLING |
  						IRQF_SHARED |
  						IRQF_ONESHOT,
  					  client->name, keypad_data);
  	if (error) {
  		dev_err(dev, "Unable to claim irq %d; error %d
  ",
  			client->irq, error);
  		return error;
  	}
  
  	error = input_register_device(input);
  	if (error) {
  		dev_err(dev, "Unable to register input device, error: %d
  ",
  			error);
  		return error;
  	}
  
  	return 0;
  }
  
  static const struct i2c_device_id tca8418_id[] = {
  	{ TCA8418_NAME, 8418, },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, tca8418_id);
  
  #ifdef CONFIG_OF
  static const struct of_device_id tca8418_dt_ids[] = {
  	{ .compatible = "ti,tca8418", },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, tca8418_dt_ids);
  
  /*
   * The device tree based i2c loader looks for
   * "i2c:" + second_component_of(property("compatible"))
   * and therefore we need an alias to be found.
   */
  MODULE_ALIAS("i2c:tca8418");
  #endif
  
  static struct i2c_driver tca8418_keypad_driver = {
  	.driver = {
  		.name	= TCA8418_NAME,
  		.of_match_table = of_match_ptr(tca8418_dt_ids),
  	},
  	.probe		= tca8418_keypad_probe,
  	.id_table	= tca8418_id,
  };
  
  static int __init tca8418_keypad_init(void)
  {
  	return i2c_add_driver(&tca8418_keypad_driver);
  }
  subsys_initcall(tca8418_keypad_init);
  
  static void __exit tca8418_keypad_exit(void)
  {
  	i2c_del_driver(&tca8418_keypad_driver);
  }
  module_exit(tca8418_keypad_exit);
  
  MODULE_AUTHOR("Kyle Manna <kyle.manna@fuel7.com>");
  MODULE_DESCRIPTION("Keypad driver for TCA8418");
  MODULE_LICENSE("GPL");