/*
 * 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/delay.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/input/matrix_keypad.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/types.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\n",
                        __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\n",
                                __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;

        do {
                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\n");
                        break;
                }

                /* Assume that key code 0 signifies empty FIFO */
                if (reg <= 0)
                        break;

                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);

        } while (1);

        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\n");
                return IRQ_NONE;
        }

        if (!reg)
                return IRQ_NONE;

        if (reg & INT_STAT_OVR_FLOW_INT)
                dev_warn(&keypad_data->client->dev, "overflow occurred\n");

        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\n");

        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 = 0;

        /* 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);

        if (error)
                return error;

        error = tca8418_write_byte(keypad_data, REG_CFG,
                                CFG_INT_CFG | CFG_OVR_FLOW_IEN | CFG_KE_IEN);

        return error;
}

static int tca8418_keypad_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct tca8418_keypad *keypad_data;
        struct input_dev *input;
        u32 rows = 0, cols = 0;
        int error, row_shift;
        u8 reg;

        /* Check i2c driver capabilities */
        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
                dev_err(dev, "%s adapter not supported\n",
                        dev_driver_string(&client->adapter->dev));
                return -ENODEV;
        }

        error = matrix_keypad_parse_properties(dev, &rows, &cols);
        if (error)
                return error;

        if (!rows || rows > TCA8418_MAX_ROWS) {
                dev_err(dev, "invalid rows\n");
                return -EINVAL;
        }

        if (!cols || cols > TCA8418_MAX_COLS) {
                dev_err(dev, "invalid columns\n");
                return -EINVAL;
        }

        row_shift = get_count_order(cols);

        /* 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;

        /* Read key lock register, if this fails assume device not present */
        error = tca8418_read_byte(keypad_data, REG_KEY_LCK_EC, &reg);
        if (error)
                return -ENODEV;

        /* 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(NULL, NULL, rows, cols, NULL, input);
        if (error) {
                dev_err(dev, "Failed to build keymap\n");
                return error;
        }

        if (device_property_read_bool(dev, "keypad,autorepeat"))
                __set_bit(EV_REP, input->evbit);

        input_set_capability(input, EV_MSC, MSC_SCAN);

        error = devm_request_threaded_irq(dev, client->irq,
                                          NULL, tca8418_irq_handler,
                                          IRQF_SHARED | IRQF_ONESHOT,
                                          client->name, keypad_data);
        if (error) {
                dev_err(dev, "Unable to claim irq %d; error %d\n",
                        client->irq, error);
                return error;
        }

        /* Initialize the chip */
        error = tca8418_configure(keypad_data, rows, cols);
        if (error < 0)
                return error;

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

        return 0;
}

static const struct i2c_device_id tca8418_id[] = {
        { .name = "tca8418", .driver_data = 8418 },
        { }
};
MODULE_DEVICE_TABLE(i2c, tca8418_id);

static const struct of_device_id tca8418_dt_ids[] = {
        { .compatible = "ti,tca8418", },
        { }
};
MODULE_DEVICE_TABLE(of, tca8418_dt_ids);

static struct i2c_driver tca8418_keypad_driver = {
        .driver = {
                .name   = "tca8418_keypad",
                .of_match_table = tca8418_dt_ids,
        },
        .probe          = tca8418_keypad_probe,
        .id_table       = tca8418_id,
};
module_i2c_driver(tca8418_keypad_driver);

MODULE_AUTHOR("Kyle Manna <kyle.manna@fuel7.com>");
MODULE_DESCRIPTION("Keypad driver for TCA8418");
MODULE_LICENSE("GPL");