/*
   * Input driver for Microchip CAP11xx based capacitive touch sensors
   *
   * (c) 2014 Daniel Mack <linux@zonque.org>
   *
   * 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/kernel.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/input.h>
  #include <linux/leds.h>
  #include <linux/of_irq.h>
  #include <linux/regmap.h>
  #include <linux/i2c.h>
  #include <linux/gpio/consumer.h>
  
  #define CAP11XX_REG_MAIN_CONTROL	0x00
  #define CAP11XX_REG_MAIN_CONTROL_GAIN_SHIFT	(6)
  #define CAP11XX_REG_MAIN_CONTROL_GAIN_MASK	(0xc0)
  #define CAP11XX_REG_MAIN_CONTROL_DLSEEP		BIT(4)
  #define CAP11XX_REG_GENERAL_STATUS	0x02
  #define CAP11XX_REG_SENSOR_INPUT	0x03
  #define CAP11XX_REG_NOISE_FLAG_STATUS	0x0a
  #define CAP11XX_REG_SENOR_DELTA(X)	(0x10 + (X))
  #define CAP11XX_REG_SENSITIVITY_CONTROL	0x1f
  #define CAP11XX_REG_CONFIG		0x20
  #define CAP11XX_REG_SENSOR_ENABLE	0x21
  #define CAP11XX_REG_SENSOR_CONFIG	0x22
  #define CAP11XX_REG_SENSOR_CONFIG2	0x23
  #define CAP11XX_REG_SAMPLING_CONFIG	0x24
  #define CAP11XX_REG_CALIBRATION		0x26
  #define CAP11XX_REG_INT_ENABLE		0x27
  #define CAP11XX_REG_REPEAT_RATE		0x28
  #define CAP11XX_REG_MT_CONFIG		0x2a
  #define CAP11XX_REG_MT_PATTERN_CONFIG	0x2b
  #define CAP11XX_REG_MT_PATTERN		0x2d
  #define CAP11XX_REG_RECALIB_CONFIG	0x2f
  #define CAP11XX_REG_SENSOR_THRESH(X)	(0x30 + (X))
  #define CAP11XX_REG_SENSOR_NOISE_THRESH	0x38
  #define CAP11XX_REG_STANDBY_CHANNEL	0x40
  #define CAP11XX_REG_STANDBY_CONFIG	0x41
  #define CAP11XX_REG_STANDBY_SENSITIVITY	0x42
  #define CAP11XX_REG_STANDBY_THRESH	0x43
  #define CAP11XX_REG_CONFIG2		0x44
  #define CAP11XX_REG_CONFIG2_ALT_POL	BIT(6)
  #define CAP11XX_REG_SENSOR_BASE_CNT(X)	(0x50 + (X))
  #define CAP11XX_REG_LED_POLARITY	0x73
  #define CAP11XX_REG_LED_OUTPUT_CONTROL	0x74
  
  #define CAP11XX_REG_LED_DUTY_CYCLE_1	0x90
  #define CAP11XX_REG_LED_DUTY_CYCLE_2	0x91
  #define CAP11XX_REG_LED_DUTY_CYCLE_3	0x92
  #define CAP11XX_REG_LED_DUTY_CYCLE_4	0x93
  
  #define CAP11XX_REG_LED_DUTY_MIN_MASK	(0x0f)
  #define CAP11XX_REG_LED_DUTY_MIN_MASK_SHIFT	(0)
  #define CAP11XX_REG_LED_DUTY_MAX_MASK	(0xf0)
  #define CAP11XX_REG_LED_DUTY_MAX_MASK_SHIFT	(4)
  #define CAP11XX_REG_LED_DUTY_MAX_VALUE	(15)
  
  #define CAP11XX_REG_SENSOR_CALIB	(0xb1 + (X))
  #define CAP11XX_REG_SENSOR_CALIB_LSB1	0xb9
  #define CAP11XX_REG_SENSOR_CALIB_LSB2	0xba
  #define CAP11XX_REG_PRODUCT_ID		0xfd
  #define CAP11XX_REG_MANUFACTURER_ID	0xfe
  #define CAP11XX_REG_REVISION		0xff
  
  #define CAP11XX_MANUFACTURER_ID	0x5d
  
  #ifdef CONFIG_LEDS_CLASS
  struct cap11xx_led {
  	struct cap11xx_priv *priv;
  	struct led_classdev cdev;
  	struct work_struct work;
  	u32 reg;
  	enum led_brightness new_brightness;
  };
  #endif
  
  struct cap11xx_priv {
  	struct regmap *regmap;
  	struct input_dev *idev;
  
  	struct cap11xx_led *leds;
  	int num_leds;
  
  	/* config */
  	u32 keycodes[];
  };
  
  struct cap11xx_hw_model {
  	u8 product_id;
  	unsigned int num_channels;
  	unsigned int num_leds;
  };
  
  enum {
  	CAP1106,
  	CAP1126,
  	CAP1188,
  };
  
  static const struct cap11xx_hw_model cap11xx_devices[] = {
  	[CAP1106] = { .product_id = 0x55, .num_channels = 6, .num_leds = 0 },
  	[CAP1126] = { .product_id = 0x53, .num_channels = 6, .num_leds = 2 },
  	[CAP1188] = { .product_id = 0x50, .num_channels = 8, .num_leds = 8 },
  };
  
  static const struct reg_default cap11xx_reg_defaults[] = {
  	{ CAP11XX_REG_MAIN_CONTROL,		0x00 },
  	{ CAP11XX_REG_GENERAL_STATUS,		0x00 },
  	{ CAP11XX_REG_SENSOR_INPUT,		0x00 },
  	{ CAP11XX_REG_NOISE_FLAG_STATUS,	0x00 },
  	{ CAP11XX_REG_SENSITIVITY_CONTROL,	0x2f },
  	{ CAP11XX_REG_CONFIG,			0x20 },
  	{ CAP11XX_REG_SENSOR_ENABLE,		0x3f },
  	{ CAP11XX_REG_SENSOR_CONFIG,		0xa4 },
  	{ CAP11XX_REG_SENSOR_CONFIG2,		0x07 },
  	{ CAP11XX_REG_SAMPLING_CONFIG,		0x39 },
  	{ CAP11XX_REG_CALIBRATION,		0x00 },
  	{ CAP11XX_REG_INT_ENABLE,		0x3f },
  	{ CAP11XX_REG_REPEAT_RATE,		0x3f },
  	{ CAP11XX_REG_MT_CONFIG,		0x80 },
  	{ CAP11XX_REG_MT_PATTERN_CONFIG,	0x00 },
  	{ CAP11XX_REG_MT_PATTERN,		0x3f },
  	{ CAP11XX_REG_RECALIB_CONFIG,		0x8a },
  	{ CAP11XX_REG_SENSOR_THRESH(0),		0x40 },
  	{ CAP11XX_REG_SENSOR_THRESH(1),		0x40 },
  	{ CAP11XX_REG_SENSOR_THRESH(2),		0x40 },
  	{ CAP11XX_REG_SENSOR_THRESH(3),		0x40 },
  	{ CAP11XX_REG_SENSOR_THRESH(4),		0x40 },
  	{ CAP11XX_REG_SENSOR_THRESH(5),		0x40 },
  	{ CAP11XX_REG_SENSOR_NOISE_THRESH,	0x01 },
  	{ CAP11XX_REG_STANDBY_CHANNEL,		0x00 },
  	{ CAP11XX_REG_STANDBY_CONFIG,		0x39 },
  	{ CAP11XX_REG_STANDBY_SENSITIVITY,	0x02 },
  	{ CAP11XX_REG_STANDBY_THRESH,		0x40 },
  	{ CAP11XX_REG_CONFIG2,			0x40 },
  	{ CAP11XX_REG_LED_POLARITY,		0x00 },
  	{ CAP11XX_REG_SENSOR_CALIB_LSB1,	0x00 },
  	{ CAP11XX_REG_SENSOR_CALIB_LSB2,	0x00 },
  };
  
  static bool cap11xx_volatile_reg(struct device *dev, unsigned int reg)
  {
  	switch (reg) {
  	case CAP11XX_REG_MAIN_CONTROL:
  	case CAP11XX_REG_SENSOR_INPUT:
  	case CAP11XX_REG_SENOR_DELTA(0):
  	case CAP11XX_REG_SENOR_DELTA(1):
  	case CAP11XX_REG_SENOR_DELTA(2):
  	case CAP11XX_REG_SENOR_DELTA(3):
  	case CAP11XX_REG_SENOR_DELTA(4):
  	case CAP11XX_REG_SENOR_DELTA(5):
  	case CAP11XX_REG_PRODUCT_ID:
  	case CAP11XX_REG_MANUFACTURER_ID:
  	case CAP11XX_REG_REVISION:
  		return true;
  	}
  
  	return false;
  }
  
  static const struct regmap_config cap11xx_regmap_config = {
  	.reg_bits = 8,
  	.val_bits = 8,
  
  	.max_register = CAP11XX_REG_REVISION,
  	.reg_defaults = cap11xx_reg_defaults,
  
  	.num_reg_defaults = ARRAY_SIZE(cap11xx_reg_defaults),
  	.cache_type = REGCACHE_RBTREE,
  	.volatile_reg = cap11xx_volatile_reg,
  };
  
  static irqreturn_t cap11xx_thread_func(int irq_num, void *data)
  {
  	struct cap11xx_priv *priv = data;
  	unsigned int status;
  	int ret, i;
  
  	/*
  	 * Deassert interrupt. This needs to be done before reading the status
  	 * registers, which will not carry valid values otherwise.
  	 */
  	ret = regmap_update_bits(priv->regmap, CAP11XX_REG_MAIN_CONTROL, 1, 0);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_read(priv->regmap, CAP11XX_REG_SENSOR_INPUT, &status);
  	if (ret < 0)
  		goto out;
  
  	for (i = 0; i < priv->idev->keycodemax; i++)
  		input_report_key(priv->idev, priv->keycodes[i],
  				 status & (1 << i));
  
  	input_sync(priv->idev);
  
  out:
  	return IRQ_HANDLED;
  }
  
  static int cap11xx_set_sleep(struct cap11xx_priv *priv, bool sleep)
  {
  	/*
  	 * DLSEEP mode will turn off all LEDS, prevent this
  	 */
  	if (IS_ENABLED(CONFIG_LEDS_CLASS) && priv->num_leds)
  		return 0;
  
  	return regmap_update_bits(priv->regmap, CAP11XX_REG_MAIN_CONTROL,
  				  CAP11XX_REG_MAIN_CONTROL_DLSEEP,
  				  sleep ? CAP11XX_REG_MAIN_CONTROL_DLSEEP : 0);
  }
  
  static int cap11xx_input_open(struct input_dev *idev)
  {
  	struct cap11xx_priv *priv = input_get_drvdata(idev);
  
  	return cap11xx_set_sleep(priv, false);
  }
  
  static void cap11xx_input_close(struct input_dev *idev)
  {
  	struct cap11xx_priv *priv = input_get_drvdata(idev);
  
  	cap11xx_set_sleep(priv, true);
  }
  
  #ifdef CONFIG_LEDS_CLASS
  static void cap11xx_led_work(struct work_struct *work)
  {
  	struct cap11xx_led *led = container_of(work, struct cap11xx_led, work);
  	struct cap11xx_priv *priv = led->priv;
  	int value = led->new_brightness;
  
  	/*
  	 * All LEDs share the same duty cycle as this is a HW limitation.
  	 * Brightness levels per LED are either 0 (OFF) and 1 (ON).
  	 */
  	regmap_update_bits(priv->regmap, CAP11XX_REG_LED_OUTPUT_CONTROL,
  				BIT(led->reg), value ? BIT(led->reg) : 0);
  }
  
  static void cap11xx_led_set(struct led_classdev *cdev,
  			   enum led_brightness value)
  {
  	struct cap11xx_led *led = container_of(cdev, struct cap11xx_led, cdev);
  
  	if (led->new_brightness == value)
  		return;
  
  	led->new_brightness = value;
  	schedule_work(&led->work);
  }
  
  static int cap11xx_init_leds(struct device *dev,
  			     struct cap11xx_priv *priv, int num_leds)
  {
  	struct device_node *node = dev->of_node, *child;
  	struct cap11xx_led *led;
  	int cnt = of_get_child_count(node);
  	int error;
  
  	if (!num_leds || !cnt)
  		return 0;
  
  	if (cnt > num_leds)
  		return -EINVAL;
  
  	led = devm_kcalloc(dev, cnt, sizeof(struct cap11xx_led), GFP_KERNEL);
  	if (!led)
  		return -ENOMEM;
  
  	priv->leds = led;
  
  	error = regmap_update_bits(priv->regmap,
  				CAP11XX_REG_LED_OUTPUT_CONTROL, 0xff, 0);
  	if (error)
  		return error;
  
  	error = regmap_update_bits(priv->regmap, CAP11XX_REG_LED_DUTY_CYCLE_4,
  				CAP11XX_REG_LED_DUTY_MAX_MASK,
  				CAP11XX_REG_LED_DUTY_MAX_VALUE <<
  				CAP11XX_REG_LED_DUTY_MAX_MASK_SHIFT);
  	if (error)
  		return error;
  
  	for_each_child_of_node(node, child) {
  		u32 reg;
  
  		led->cdev.name =
  			of_get_property(child, "label", NULL) ? : child->name;
  		led->cdev.default_trigger =
  			of_get_property(child, "linux,default-trigger", NULL);
  		led->cdev.flags = 0;
  		led->cdev.brightness_set = cap11xx_led_set;
  		led->cdev.max_brightness = 1;
  		led->cdev.brightness = LED_OFF;
  
  		error = of_property_read_u32(child, "reg", &reg);
  		if (error != 0 || reg >= num_leds)
  			return -EINVAL;
  
  		led->reg = reg;
  		led->priv = priv;
  
  		INIT_WORK(&led->work, cap11xx_led_work);
  
  		error = devm_led_classdev_register(dev, &led->cdev);
  		if (error)
  			return error;
  
  		priv->num_leds++;
  		led++;
  	}
  
  	return 0;
  }
  #else
  static int cap11xx_init_leds(struct device *dev,
  			     struct cap11xx_priv *priv, int num_leds)
  {
  	return 0;
  }
  #endif
  
  static int cap11xx_i2c_probe(struct i2c_client *i2c_client,
  			     const struct i2c_device_id *id)
  {
  	struct device *dev = &i2c_client->dev;
  	struct cap11xx_priv *priv;
  	struct device_node *node;
  	const struct cap11xx_hw_model *cap;
  	int i, error, irq, gain = 0;
  	unsigned int val, rev;
  	u32 gain32;
  
  	if (id->driver_data >= ARRAY_SIZE(cap11xx_devices)) {
  		dev_err(dev, "Invalid device ID %lu
  ", id->driver_data);
  		return -EINVAL;
  	}
  
  	cap = &cap11xx_devices[id->driver_data];
  	if (!cap || !cap->num_channels) {
  		dev_err(dev, "Invalid device configuration
  ");
  		return -EINVAL;
  	}
  
  	priv = devm_kzalloc(dev,
  			    sizeof(*priv) +
  				cap->num_channels * sizeof(priv->keycodes[0]),
  			    GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	priv->regmap = devm_regmap_init_i2c(i2c_client, &cap11xx_regmap_config);
  	if (IS_ERR(priv->regmap))
  		return PTR_ERR(priv->regmap);
  
  	error = regmap_read(priv->regmap, CAP11XX_REG_PRODUCT_ID, &val);
  	if (error)
  		return error;
  
  	if (val != cap->product_id) {
  		dev_err(dev, "Product ID: Got 0x%02x, expected 0x%02x
  ",
  			val, cap->product_id);
  		return -ENXIO;
  	}
  
  	error = regmap_read(priv->regmap, CAP11XX_REG_MANUFACTURER_ID, &val);
  	if (error)
  		return error;
  
  	if (val != CAP11XX_MANUFACTURER_ID) {
  		dev_err(dev, "Manufacturer ID: Got 0x%02x, expected 0x%02x
  ",
  			val, CAP11XX_MANUFACTURER_ID);
  		return -ENXIO;
  	}
  
  	error = regmap_read(priv->regmap, CAP11XX_REG_REVISION, &rev);
  	if (error < 0)
  		return error;
  
  	dev_info(dev, "CAP11XX detected, revision 0x%02x
  ", rev);
  	i2c_set_clientdata(i2c_client, priv);
  	node = dev->of_node;
  
  	if (!of_property_read_u32(node, "microchip,sensor-gain", &gain32)) {
  		if (is_power_of_2(gain32) && gain32 <= 8)
  			gain = ilog2(gain32);
  		else
  			dev_err(dev, "Invalid sensor-gain value %d
  ", gain32);
  	}
  
  	if (of_property_read_bool(node, "microchip,irq-active-high")) {
  		error = regmap_update_bits(priv->regmap, CAP11XX_REG_CONFIG2,
  					   CAP11XX_REG_CONFIG2_ALT_POL, 0);
  		if (error)
  			return error;
  	}
  
  	/* Provide some useful defaults */
  	for (i = 0; i < cap->num_channels; i++)
  		priv->keycodes[i] = KEY_A + i;
  
  	of_property_read_u32_array(node, "linux,keycodes",
  				   priv->keycodes, cap->num_channels);
  
  	error = regmap_update_bits(priv->regmap, CAP11XX_REG_MAIN_CONTROL,
  				   CAP11XX_REG_MAIN_CONTROL_GAIN_MASK,
  				   gain << CAP11XX_REG_MAIN_CONTROL_GAIN_SHIFT);
  	if (error)
  		return error;
  
  	/* Disable autorepeat. The Linux input system has its own handling. */
  	error = regmap_write(priv->regmap, CAP11XX_REG_REPEAT_RATE, 0);
  	if (error)
  		return error;
  
  	priv->idev = devm_input_allocate_device(dev);
  	if (!priv->idev)
  		return -ENOMEM;
  
  	priv->idev->name = "CAP11XX capacitive touch sensor";
  	priv->idev->id.bustype = BUS_I2C;
  	priv->idev->evbit[0] = BIT_MASK(EV_KEY);
  
  	if (of_property_read_bool(node, "autorepeat"))
  		__set_bit(EV_REP, priv->idev->evbit);
  
  	for (i = 0; i < cap->num_channels; i++)
  		__set_bit(priv->keycodes[i], priv->idev->keybit);
  
  	__clear_bit(KEY_RESERVED, priv->idev->keybit);
  
  	priv->idev->keycode = priv->keycodes;
  	priv->idev->keycodesize = sizeof(priv->keycodes[0]);
  	priv->idev->keycodemax = cap->num_channels;
  
  	priv->idev->id.vendor = CAP11XX_MANUFACTURER_ID;
  	priv->idev->id.product = cap->product_id;
  	priv->idev->id.version = rev;
  
  	priv->idev->open = cap11xx_input_open;
  	priv->idev->close = cap11xx_input_close;
  
  	error = cap11xx_init_leds(dev, priv, cap->num_leds);
  	if (error)
  		return error;
  
  	input_set_drvdata(priv->idev, priv);
  
  	/*
  	 * Put the device in deep sleep mode for now.
  	 * ->open() will bring it back once the it is actually needed.
  	 */
  	cap11xx_set_sleep(priv, true);
  
  	error = input_register_device(priv->idev);
  	if (error)
  		return error;
  
  	irq = irq_of_parse_and_map(node, 0);
  	if (!irq) {
  		dev_err(dev, "Unable to parse or map IRQ
  ");
  		return -ENXIO;
  	}
  
  	error = devm_request_threaded_irq(dev, irq, NULL, cap11xx_thread_func,
  					  IRQF_ONESHOT, dev_name(dev), priv);
  	if (error)
  		return error;
  
  	return 0;
  }
  
  static const struct of_device_id cap11xx_dt_ids[] = {
  	{ .compatible = "microchip,cap1106", },
  	{ .compatible = "microchip,cap1126", },
  	{ .compatible = "microchip,cap1188", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, cap11xx_dt_ids);
  
  static const struct i2c_device_id cap11xx_i2c_ids[] = {
  	{ "cap1106", CAP1106 },
  	{ "cap1126", CAP1126 },
  	{ "cap1188", CAP1188 },
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, cap11xx_i2c_ids);
  
  static struct i2c_driver cap11xx_i2c_driver = {
  	.driver = {
  		.name	= "cap11xx",
  		.of_match_table = cap11xx_dt_ids,
  	},
  	.id_table	= cap11xx_i2c_ids,
  	.probe		= cap11xx_i2c_probe,
  };
  
  module_i2c_driver(cap11xx_i2c_driver);
  
  MODULE_DESCRIPTION("Microchip CAP11XX driver");
  MODULE_AUTHOR("Daniel Mack <linux@zonque.org>");
  MODULE_LICENSE("GPL v2");