/*
 * Touchkey driver for Freescale MPR121 Controllor
 *
 * Copyright (C) 2011 Freescale Semiconductor, Inc.
 * Author: Zhang Jiejing <jiejing.zhang@freescale.com>
 *
 * Based on mcs_touchkey.c
 *
 * 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/module.h>
#include <linux/input.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/i2c/mpr121_touchkey.h>

/* Register definitions */
#define ELE_TOUCH_STATUS_0_ADDR	0x0
#define ELE_TOUCH_STATUS_1_ADDR	0X1
#define MHD_RISING_ADDR		0x2b
#define NHD_RISING_ADDR		0x2c
#define NCL_RISING_ADDR		0x2d
#define FDL_RISING_ADDR		0x2e
#define MHD_FALLING_ADDR	0x2f
#define NHD_FALLING_ADDR	0x30
#define NCL_FALLING_ADDR	0x31
#define FDL_FALLING_ADDR	0x32
#define ELE0_TOUCH_THRESHOLD_ADDR	0x41
#define ELE0_RELEASE_THRESHOLD_ADDR	0x42
#define AFE_CONF_ADDR			0x5c
#define FILTER_CONF_ADDR		0x5d

/*
 * ELECTRODE_CONF_ADDR: This register configures the number of
 * enabled capacitance sensing inputs and its run/suspend mode.
 */
#define ELECTRODE_CONF_ADDR		0x5e
#define ELECTRODE_CONF_QUICK_CHARGE	0x80
#define AUTO_CONFIG_CTRL_ADDR		0x7b
#define AUTO_CONFIG_USL_ADDR		0x7d
#define AUTO_CONFIG_LSL_ADDR		0x7e
#define AUTO_CONFIG_TL_ADDR		0x7f

/* Threshold of touch/release trigger */
#define TOUCH_THRESHOLD			0x08
#define RELEASE_THRESHOLD		0x05
/* Masks for touch and release triggers */
#define TOUCH_STATUS_MASK		0xfff
/* MPR121 has 12 keys */
#define MPR121_MAX_KEY_COUNT		12

struct mpr121_touchkey {
	struct i2c_client	*client;
	struct input_dev	*input_dev;
	unsigned int		key_val;
	unsigned int		statusbits;
	unsigned int		keycount;
	u16			keycodes[MPR121_MAX_KEY_COUNT];
};

struct mpr121_init_register {
	int addr;
	u8 val;
};

static const struct mpr121_init_register init_reg_table[] = {
	{ MHD_RISING_ADDR,	0x1 },
	{ NHD_RISING_ADDR,	0x1 },
	{ MHD_FALLING_ADDR,	0x1 },
	{ NHD_FALLING_ADDR,	0x1 },
	{ NCL_FALLING_ADDR,	0xff },
	{ FDL_FALLING_ADDR,	0x02 },
	{ FILTER_CONF_ADDR,	0x04 },
	{ AFE_CONF_ADDR,	0x0b },
	{ AUTO_CONFIG_CTRL_ADDR, 0x0b },
};

static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
{
	struct mpr121_touchkey *mpr121 = dev_id;
	struct i2c_client *client = mpr121->client;
	struct input_dev *input = mpr121->input_dev;
	unsigned long bit_changed;
	unsigned int key_num;
	int reg;

	reg = i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_1_ADDR);
	if (reg < 0) {
		dev_err(&client->dev, "i2c read error [%d]\n", reg);
		goto out;
	}

	reg <<= 8;
	reg |= i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_0_ADDR);
	if (reg < 0) {
		dev_err(&client->dev, "i2c read error [%d]\n", reg);
		goto out;
	}

	reg &= TOUCH_STATUS_MASK;
	/* use old press bit to figure out which bit changed */
	bit_changed = reg ^ mpr121->statusbits;
	mpr121->statusbits = reg;
	for_each_set_bit(key_num, &bit_changed, mpr121->keycount) {
		unsigned int key_val, pressed;

		pressed = reg & BIT(key_num);
		key_val = mpr121->keycodes[key_num];

		input_event(input, EV_MSC, MSC_SCAN, key_num);
		input_report_key(input, key_val, pressed);

		dev_dbg(&client->dev, "key %d %d %s\n", key_num, key_val,
			pressed ? "pressed" : "released");

	}
	input_sync(input);

out:
	return IRQ_HANDLED;
}

static int mpr121_phys_init(const struct mpr121_platform_data *pdata,
				      struct mpr121_touchkey *mpr121,
				      struct i2c_client *client)
{
	const struct mpr121_init_register *reg;
	unsigned char usl, lsl, tl, eleconf;
	int i, t, vdd, ret;

	/* Set up touch/release threshold for ele0-ele11 */
	for (i = 0; i <= MPR121_MAX_KEY_COUNT; i++) {
		t = ELE0_TOUCH_THRESHOLD_ADDR + (i * 2);
		ret = i2c_smbus_write_byte_data(client, t, TOUCH_THRESHOLD);
		if (ret < 0)
			goto err_i2c_write;
		ret = i2c_smbus_write_byte_data(client, t + 1,
						RELEASE_THRESHOLD);
		if (ret < 0)
			goto err_i2c_write;
	}

	/* Set up init register */
	for (i = 0; i < ARRAY_SIZE(init_reg_table); i++) {
		reg = &init_reg_table[i];
		ret = i2c_smbus_write_byte_data(client, reg->addr, reg->val);
		if (ret < 0)
			goto err_i2c_write;
	}


	/*
	 * Capacitance on sensing input varies and needs to be compensated.
	 * The internal MPR121-auto-configuration can do this if it's
	 * registers are set properly (based on pdata->vdd_uv).
	 */
	vdd = pdata->vdd_uv / 1000;
	usl = ((vdd - 700) * 256) / vdd;
	lsl = (usl * 65) / 100;
	tl = (usl * 90) / 100;
	ret = i2c_smbus_write_byte_data(client, AUTO_CONFIG_USL_ADDR, usl);
	ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_LSL_ADDR, lsl);
	ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_TL_ADDR, tl);

	/*
	 * Quick charge bit will let the capacitive charge to ready
	 * state quickly, or the buttons may not function after system
	 * boot.
	 */
	eleconf = mpr121->keycount | ELECTRODE_CONF_QUICK_CHARGE;
	ret |= i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
					 eleconf);
	if (ret != 0)
		goto err_i2c_write;

	dev_dbg(&client->dev, "set up with %x keys.\n", mpr121->keycount);

	return 0;

err_i2c_write:
	dev_err(&client->dev, "i2c write error: %d\n", ret);
	return ret;
}

static int mpr_touchkey_probe(struct i2c_client *client,
			      const struct i2c_device_id *id)
{
	const struct mpr121_platform_data *pdata =
			dev_get_platdata(&client->dev);
	struct mpr121_touchkey *mpr121;
	struct input_dev *input_dev;
	int error;
	int i;

	if (!pdata) {
		dev_err(&client->dev, "no platform data defined\n");
		return -EINVAL;
	}

	if (!pdata->keymap || !pdata->keymap_size) {
		dev_err(&client->dev, "missing keymap data\n");
		return -EINVAL;
	}

	if (pdata->keymap_size > MPR121_MAX_KEY_COUNT) {
		dev_err(&client->dev, "too many keys defined\n");
		return -EINVAL;
	}

	if (!client->irq) {
		dev_err(&client->dev, "irq number should not be zero\n");
		return -EINVAL;
	}

	mpr121 = devm_kzalloc(&client->dev, sizeof(*mpr121),
			      GFP_KERNEL);
	if (!mpr121)
		return -ENOMEM;

	input_dev = devm_input_allocate_device(&client->dev);
	if (!input_dev)
		return -ENOMEM;

	mpr121->client = client;
	mpr121->input_dev = input_dev;
	mpr121->keycount = pdata->keymap_size;

	input_dev->name = "Freescale MPR121 Touchkey";
	input_dev->id.bustype = BUS_I2C;
	input_dev->dev.parent = &client->dev;
	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
	input_set_capability(input_dev, EV_MSC, MSC_SCAN);

	input_dev->keycode = mpr121->keycodes;
	input_dev->keycodesize = sizeof(mpr121->keycodes[0]);
	input_dev->keycodemax = mpr121->keycount;

	for (i = 0; i < pdata->keymap_size; i++) {
		input_set_capability(input_dev, EV_KEY, pdata->keymap[i]);
		mpr121->keycodes[i] = pdata->keymap[i];
	}

	error = mpr121_phys_init(pdata, mpr121, client);
	if (error) {
		dev_err(&client->dev, "Failed to init register\n");
		return error;
	}

	error = devm_request_threaded_irq(&client->dev, client->irq, NULL,
				     mpr_touchkey_interrupt,
				     IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
				     client->dev.driver->name, mpr121);
	if (error) {
		dev_err(&client->dev, "Failed to register interrupt\n");
		return error;
	}

	error = input_register_device(input_dev);
	if (error)
		return error;

	i2c_set_clientdata(client, mpr121);
	device_init_wakeup(&client->dev, pdata->wakeup);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int mpr_suspend(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);

	if (device_may_wakeup(&client->dev))
		enable_irq_wake(client->irq);

	i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR, 0x00);

	return 0;
}

static int mpr_resume(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct mpr121_touchkey *mpr121 = i2c_get_clientdata(client);

	if (device_may_wakeup(&client->dev))
		disable_irq_wake(client->irq);

	i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
				  mpr121->keycount);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(mpr121_touchkey_pm_ops, mpr_suspend, mpr_resume);

static const struct i2c_device_id mpr121_id[] = {
	{ "mpr121_touchkey", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, mpr121_id);

static struct i2c_driver mpr_touchkey_driver = {
	.driver = {
		.name	= "mpr121",
		.pm	= &mpr121_touchkey_pm_ops,
	},
	.id_table	= mpr121_id,
	.probe		= mpr_touchkey_probe,
};

module_i2c_driver(mpr_touchkey_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Zhang Jiejing <jiejing.zhang@freescale.com>");
MODULE_DESCRIPTION("Touch Key driver for Freescale MPR121 Chip");