/* -------------------------------------------------------------------------
 * Copyright (C) 2014-2015, Intel Corporation
 *
 * Derived from:
 *  gslX68X.c
 *  Copyright (C) 2010-2015, Shanghai Sileadinc Co.Ltd
 *
 *  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; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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.
 * -------------------------------------------------------------------------
 */

#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/gpio/consumer.h>
#include <linux/delay.h>
#include <linux/firmware.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/input/touchscreen.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/irq.h>
#include <linux/regulator/consumer.h>

#include <asm/unaligned.h>

#define SILEAD_TS_NAME		"silead_ts"

#define SILEAD_REG_RESET	0xE0
#define SILEAD_REG_DATA		0x80
#define SILEAD_REG_TOUCH_NR	0x80
#define SILEAD_REG_POWER	0xBC
#define SILEAD_REG_CLOCK	0xE4
#define SILEAD_REG_STATUS	0xB0
#define SILEAD_REG_ID		0xFC
#define SILEAD_REG_MEM_CHECK	0xB0

#define SILEAD_STATUS_OK	0x5A5A5A5A
#define SILEAD_TS_DATA_LEN	44
#define SILEAD_CLOCK		0x04

#define SILEAD_CMD_RESET	0x88
#define SILEAD_CMD_START	0x00

#define SILEAD_POINT_DATA_LEN	0x04
#define SILEAD_POINT_Y_OFF      0x00
#define SILEAD_POINT_Y_MSB_OFF	0x01
#define SILEAD_POINT_X_OFF	0x02
#define SILEAD_POINT_X_MSB_OFF	0x03
#define SILEAD_EXTRA_DATA_MASK	0xF0

#define SILEAD_CMD_SLEEP_MIN	10000
#define SILEAD_CMD_SLEEP_MAX	20000
#define SILEAD_POWER_SLEEP	20
#define SILEAD_STARTUP_SLEEP	30

#define SILEAD_MAX_FINGERS	10

enum silead_ts_power {
	SILEAD_POWER_ON  = 1,
	SILEAD_POWER_OFF = 0
};

struct silead_ts_data {
	struct i2c_client *client;
	struct gpio_desc *gpio_power;
	struct input_dev *input;
	struct regulator_bulk_data regulators[2];
	char fw_name[64];
	struct touchscreen_properties prop;
	u32 max_fingers;
	u32 chip_id;
	struct input_mt_pos pos[SILEAD_MAX_FINGERS];
	int slots[SILEAD_MAX_FINGERS];
	int id[SILEAD_MAX_FINGERS];
};

struct silead_fw_data {
	u32 offset;
	u32 val;
};

static int silead_ts_request_input_dev(struct silead_ts_data *data)
{
	struct device *dev = &data->client->dev;
	int error;

	data->input = devm_input_allocate_device(dev);
	if (!data->input) {
		dev_err(dev,
			"Failed to allocate input device\n");
		return -ENOMEM;
	}

	input_set_abs_params(data->input, ABS_MT_POSITION_X, 0, 4095, 0, 0);
	input_set_abs_params(data->input, ABS_MT_POSITION_Y, 0, 4095, 0, 0);
	touchscreen_parse_properties(data->input, true, &data->prop);

	input_mt_init_slots(data->input, data->max_fingers,
			    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED |
			    INPUT_MT_TRACK);

	if (device_property_read_bool(dev, "silead,home-button"))
		input_set_capability(data->input, EV_KEY, KEY_LEFTMETA);

	data->input->name = SILEAD_TS_NAME;
	data->input->phys = "input/ts";
	data->input->id.bustype = BUS_I2C;

	error = input_register_device(data->input);
	if (error) {
		dev_err(dev, "Failed to register input device: %d\n", error);
		return error;
	}

	return 0;
}

static void silead_ts_set_power(struct i2c_client *client,
				enum silead_ts_power state)
{
	struct silead_ts_data *data = i2c_get_clientdata(client);

	if (data->gpio_power) {
		gpiod_set_value_cansleep(data->gpio_power, state);
		msleep(SILEAD_POWER_SLEEP);
	}
}

static void silead_ts_read_data(struct i2c_client *client)
{
	struct silead_ts_data *data = i2c_get_clientdata(client);
	struct input_dev *input = data->input;
	struct device *dev = &client->dev;
	u8 *bufp, buf[SILEAD_TS_DATA_LEN];
	int touch_nr, softbutton, error, i;
	bool softbutton_pressed = false;

	error = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_DATA,
					      SILEAD_TS_DATA_LEN, buf);
	if (error < 0) {
		dev_err(dev, "Data read error %d\n", error);
		return;
	}

	if (buf[0] > data->max_fingers) {
		dev_warn(dev, "More touches reported then supported %d > %d\n",
			 buf[0], data->max_fingers);
		buf[0] = data->max_fingers;
	}

	touch_nr = 0;
	bufp = buf + SILEAD_POINT_DATA_LEN;
	for (i = 0; i < buf[0]; i++, bufp += SILEAD_POINT_DATA_LEN) {
		softbutton = (bufp[SILEAD_POINT_Y_MSB_OFF] &
			      SILEAD_EXTRA_DATA_MASK) >> 4;

		if (softbutton) {
			/*
			 * For now only respond to softbutton == 0x01, some
			 * tablets *without* a capacative button send 0x04
			 * when crossing the edges of the screen.
			 */
			if (softbutton == 0x01)
				softbutton_pressed = true;

			continue;
		}

		/*
		 * Bits 4-7 are the touch id, note not all models have
		 * hardware touch ids so atm we don't use these.
		 */
		data->id[touch_nr] = (bufp[SILEAD_POINT_X_MSB_OFF] &
				      SILEAD_EXTRA_DATA_MASK) >> 4;
		touchscreen_set_mt_pos(&data->pos[touch_nr], &data->prop,
			get_unaligned_le16(&bufp[SILEAD_POINT_X_OFF]) & 0xfff,
			get_unaligned_le16(&bufp[SILEAD_POINT_Y_OFF]) & 0xfff);
		touch_nr++;
	}

	input_mt_assign_slots(input, data->slots, data->pos, touch_nr, 0);

	for (i = 0; i < touch_nr; i++) {
		input_mt_slot(input, data->slots[i]);
		input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
		input_report_abs(input, ABS_MT_POSITION_X, data->pos[i].x);
		input_report_abs(input, ABS_MT_POSITION_Y, data->pos[i].y);

		dev_dbg(dev, "x=%d y=%d hw_id=%d sw_id=%d\n", data->pos[i].x,
			data->pos[i].y, data->id[i], data->slots[i]);
	}

	input_mt_sync_frame(input);
	input_report_key(input, KEY_LEFTMETA, softbutton_pressed);
	input_sync(input);
}

static int silead_ts_init(struct i2c_client *client)
{
	struct silead_ts_data *data = i2c_get_clientdata(client);
	int error;

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_RESET,
					  SILEAD_CMD_RESET);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_TOUCH_NR,
					data->max_fingers);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_CLOCK,
					  SILEAD_CLOCK);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_RESET,
					  SILEAD_CMD_START);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	return 0;

i2c_write_err:
	dev_err(&client->dev, "Registers clear error %d\n", error);
	return error;
}

static int silead_ts_reset(struct i2c_client *client)
{
	int error;

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_RESET,
					  SILEAD_CMD_RESET);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_CLOCK,
					  SILEAD_CLOCK);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_POWER,
					  SILEAD_CMD_START);
	if (error)
		goto i2c_write_err;
	usleep_range(SILEAD_CMD_SLEEP_MIN, SILEAD_CMD_SLEEP_MAX);

	return 0;

i2c_write_err:
	dev_err(&client->dev, "Chip reset error %d\n", error);
	return error;
}

static int silead_ts_startup(struct i2c_client *client)
{
	int error;

	error = i2c_smbus_write_byte_data(client, SILEAD_REG_RESET, 0x00);
	if (error) {
		dev_err(&client->dev, "Startup error %d\n", error);
		return error;
	}

	msleep(SILEAD_STARTUP_SLEEP);

	return 0;
}

static int silead_ts_load_fw(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct silead_ts_data *data = i2c_get_clientdata(client);
	unsigned int fw_size, i;
	const struct firmware *fw;
	struct silead_fw_data *fw_data;
	int error;

	dev_dbg(dev, "Firmware file name: %s", data->fw_name);

	error = request_firmware(&fw, data->fw_name, dev);
	if (error) {
		dev_err(dev, "Firmware request error %d\n", error);
		return error;
	}

	fw_size = fw->size / sizeof(*fw_data);
	fw_data = (struct silead_fw_data *)fw->data;

	for (i = 0; i < fw_size; i++) {
		error = i2c_smbus_write_i2c_block_data(client,
						       fw_data[i].offset,
						       4,
						       (u8 *)&fw_data[i].val);
		if (error) {
			dev_err(dev, "Firmware load error %d\n", error);
			break;
		}
	}

	release_firmware(fw);
	return error ?: 0;
}

static u32 silead_ts_get_status(struct i2c_client *client)
{
	int error;
	__le32 status;

	error = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_STATUS,
					      sizeof(status), (u8 *)&status);
	if (error < 0) {
		dev_err(&client->dev, "Status read error %d\n", error);
		return error;
	}

	return le32_to_cpu(status);
}

static int silead_ts_get_id(struct i2c_client *client)
{
	struct silead_ts_data *data = i2c_get_clientdata(client);
	__le32 chip_id;
	int error;

	error = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_ID,
					      sizeof(chip_id), (u8 *)&chip_id);
	if (error < 0)
		return error;

	data->chip_id = le32_to_cpu(chip_id);
	dev_info(&client->dev, "Silead chip ID: 0x%8X", data->chip_id);

	return 0;
}

static int silead_ts_setup(struct i2c_client *client)
{
	int error;
	u32 status;

	/*
	 * Some buggy BIOS-es bring up the chip in a stuck state where it
	 * blocks the I2C bus. The following steps are necessary to
	 * unstuck the chip / bus:
	 * 1. Turn off the Silead chip.
	 * 2. Try to do an I2C transfer with the chip, this will fail in
	 *    response to which the I2C-bus-driver will call:
	 *    i2c_recover_bus() which will unstuck the I2C-bus. Note the
	 *    unstuck-ing of the I2C bus only works if we first drop the
	 *    chip off the bus by turning it off.
	 * 3. Turn the chip back on.
	 *
	 * On the x86/ACPI systems were this problem is seen, step 1. and
	 * 3. require making ACPI calls and dealing with ACPI Power
	 * Resources. The workaround below runtime-suspends the chip to
	 * turn it off, leaving it up to the ACPI subsystem to deal with
	 * this.
	 */

	if (device_property_read_bool(&client->dev,
				      "silead,stuck-controller-bug")) {
		pm_runtime_set_active(&client->dev);
		pm_runtime_enable(&client->dev);
		pm_runtime_allow(&client->dev);

		pm_runtime_suspend(&client->dev);

		dev_warn(&client->dev, FW_BUG "Stuck I2C bus: please ignore the next 'controller timed out' error\n");
		silead_ts_get_id(client);

		/* The forbid will also resume the device */
		pm_runtime_forbid(&client->dev);
		pm_runtime_disable(&client->dev);
	}

	silead_ts_set_power(client, SILEAD_POWER_OFF);
	silead_ts_set_power(client, SILEAD_POWER_ON);

	error = silead_ts_get_id(client);
	if (error) {
		dev_err(&client->dev, "Chip ID read error %d\n", error);
		return error;
	}

	error = silead_ts_init(client);
	if (error)
		return error;

	error = silead_ts_reset(client);
	if (error)
		return error;

	error = silead_ts_load_fw(client);
	if (error)
		return error;

	error = silead_ts_startup(client);
	if (error)
		return error;

	status = silead_ts_get_status(client);
	if (status != SILEAD_STATUS_OK) {
		dev_err(&client->dev,
			"Initialization error, status: 0x%X\n", status);
		return -ENODEV;
	}

	return 0;
}

static irqreturn_t silead_ts_threaded_irq_handler(int irq, void *id)
{
	struct silead_ts_data *data = id;
	struct i2c_client *client = data->client;

	silead_ts_read_data(client);

	return IRQ_HANDLED;
}

static void silead_ts_read_props(struct i2c_client *client)
{
	struct silead_ts_data *data = i2c_get_clientdata(client);
	struct device *dev = &client->dev;
	const char *str;
	int error;

	error = device_property_read_u32(dev, "silead,max-fingers",
					 &data->max_fingers);
	if (error) {
		dev_dbg(dev, "Max fingers read error %d\n", error);
		data->max_fingers = 5; /* Most devices handle up-to 5 fingers */
	}

	error = device_property_read_string(dev, "firmware-name", &str);
	if (!error)
		snprintf(data->fw_name, sizeof(data->fw_name),
			 "silead/%s", str);
	else
		dev_dbg(dev, "Firmware file name read error. Using default.");
}

#ifdef CONFIG_ACPI
static int silead_ts_set_default_fw_name(struct silead_ts_data *data,
					 const struct i2c_device_id *id)
{
	const struct acpi_device_id *acpi_id;
	struct device *dev = &data->client->dev;
	int i;

	if (ACPI_HANDLE(dev)) {
		acpi_id = acpi_match_device(dev->driver->acpi_match_table, dev);
		if (!acpi_id)
			return -ENODEV;

		snprintf(data->fw_name, sizeof(data->fw_name),
			 "silead/%s.fw", acpi_id->id);

		for (i = 0; i < strlen(data->fw_name); i++)
			data->fw_name[i] = tolower(data->fw_name[i]);
	} else {
		snprintf(data->fw_name, sizeof(data->fw_name),
			 "silead/%s.fw", id->name);
	}

	return 0;
}
#else
static int silead_ts_set_default_fw_name(struct silead_ts_data *data,
					 const struct i2c_device_id *id)
{
	snprintf(data->fw_name, sizeof(data->fw_name),
		 "silead/%s.fw", id->name);
	return 0;
}
#endif

static void silead_disable_regulator(void *arg)
{
	struct silead_ts_data *data = arg;

	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
}

static int silead_ts_probe(struct i2c_client *client,
			   const struct i2c_device_id *id)
{
	struct silead_ts_data *data;
	struct device *dev = &client->dev;
	int error;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_I2C |
				     I2C_FUNC_SMBUS_READ_I2C_BLOCK |
				     I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
		dev_err(dev, "I2C functionality check failed\n");
		return -ENXIO;
	}

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	i2c_set_clientdata(client, data);
	data->client = client;

	error = silead_ts_set_default_fw_name(data, id);
	if (error)
		return error;

	silead_ts_read_props(client);

	/* We must have the IRQ provided by DT or ACPI subsytem */
	if (client->irq <= 0)
		return -ENODEV;

	data->regulators[0].supply = "vddio";
	data->regulators[1].supply = "avdd";
	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->regulators),
					data->regulators);
	if (error)
		return error;

	/*
	 * Enable regulators at probe and disable them at remove, we need
	 * to keep the chip powered otherwise it forgets its firmware.
	 */
	error = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
				      data->regulators);
	if (error)
		return error;

	error = devm_add_action_or_reset(dev, silead_disable_regulator, data);
	if (error)
		return error;

	/* Power GPIO pin */
	data->gpio_power = devm_gpiod_get_optional(dev, "power", GPIOD_OUT_LOW);
	if (IS_ERR(data->gpio_power)) {
		if (PTR_ERR(data->gpio_power) != -EPROBE_DEFER)
			dev_err(dev, "Shutdown GPIO request failed\n");
		return PTR_ERR(data->gpio_power);
	}

	error = silead_ts_setup(client);
	if (error)
		return error;

	error = silead_ts_request_input_dev(data);
	if (error)
		return error;

	error = devm_request_threaded_irq(dev, client->irq,
					  NULL, silead_ts_threaded_irq_handler,
					  IRQF_ONESHOT, client->name, data);
	if (error) {
		if (error != -EPROBE_DEFER)
			dev_err(dev, "IRQ request failed %d\n", error);
		return error;
	}

	return 0;
}

static int __maybe_unused silead_ts_suspend(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);

	disable_irq(client->irq);
	silead_ts_set_power(client, SILEAD_POWER_OFF);
	return 0;
}

static int __maybe_unused silead_ts_resume(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	bool second_try = false;
	int error, status;

	silead_ts_set_power(client, SILEAD_POWER_ON);

 retry:
	error = silead_ts_reset(client);
	if (error)
		return error;

	if (second_try) {
		error = silead_ts_load_fw(client);
		if (error)
			return error;
	}

	error = silead_ts_startup(client);
	if (error)
		return error;

	status = silead_ts_get_status(client);
	if (status != SILEAD_STATUS_OK) {
		if (!second_try) {
			second_try = true;
			dev_dbg(dev, "Reloading firmware after unsuccessful resume\n");
			goto retry;
		}
		dev_err(dev, "Resume error, status: 0x%02x\n", status);
		return -ENODEV;
	}

	enable_irq(client->irq);

	return 0;
}

static SIMPLE_DEV_PM_OPS(silead_ts_pm, silead_ts_suspend, silead_ts_resume);

static const struct i2c_device_id silead_ts_id[] = {
	{ "gsl1680", 0 },
	{ "gsl1688", 0 },
	{ "gsl3670", 0 },
	{ "gsl3675", 0 },
	{ "gsl3692", 0 },
	{ "mssl1680", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, silead_ts_id);

#ifdef CONFIG_ACPI
static const struct acpi_device_id silead_ts_acpi_match[] = {
	{ "GSL1680", 0 },
	{ "GSL1688", 0 },
	{ "GSL3670", 0 },
	{ "GSL3675", 0 },
	{ "GSL3692", 0 },
	{ "MSSL1680", 0 },
	{ "MSSL0001", 0 },
	{ "MSSL0002", 0 },
	{ "MSSL0017", 0 },
	{ }
};
MODULE_DEVICE_TABLE(acpi, silead_ts_acpi_match);
#endif

#ifdef CONFIG_OF
static const struct of_device_id silead_ts_of_match[] = {
	{ .compatible = "silead,gsl1680" },
	{ .compatible = "silead,gsl1688" },
	{ .compatible = "silead,gsl3670" },
	{ .compatible = "silead,gsl3675" },
	{ .compatible = "silead,gsl3692" },
	{ },
};
MODULE_DEVICE_TABLE(of, silead_ts_of_match);
#endif

static struct i2c_driver silead_ts_driver = {
	.probe = silead_ts_probe,
	.id_table = silead_ts_id,
	.driver = {
		.name = SILEAD_TS_NAME,
		.acpi_match_table = ACPI_PTR(silead_ts_acpi_match),
		.of_match_table = of_match_ptr(silead_ts_of_match),
		.pm = &silead_ts_pm,
	},
};
module_i2c_driver(silead_ts_driver);

MODULE_AUTHOR("Robert Dolca <robert.dolca@intel.com>");
MODULE_DESCRIPTION("Silead I2C touchscreen driver");
MODULE_LICENSE("GPL");