/*
 * Copyright (C) 2011 Kionix, Inc.
 * Written by Chris Hudson <chudson@kionix.com>
 *
 * 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.
 *
 * 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
 * 02111-1307, USA
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input/kxtj9.h>
#include <linux/input-polldev.h>

#define NAME                    "kxtj9"
#define G_MAX                   8000
/* OUTPUT REGISTERS */
#define XOUT_L                  0x06
#define WHO_AM_I                0x0F
/* CONTROL REGISTERS */
#define INT_REL                 0x1A
#define CTRL_REG1               0x1B
#define INT_CTRL1               0x1E
#define DATA_CTRL               0x21
/* CONTROL REGISTER 1 BITS */
#define PC1_OFF                 0x7F
#define PC1_ON                  (1 << 7)
/* Data ready funtion enable bit: set during probe if using irq mode */
#define DRDYE                   (1 << 5)
/* DATA CONTROL REGISTER BITS */
#define ODR12_5F                0
#define ODR25F                  1
#define ODR50F                  2
#define ODR100F         3
#define ODR200F         4
#define ODR400F         5
#define ODR800F         6
/* INTERRUPT CONTROL REGISTER 1 BITS */
/* Set these during probe if using irq mode */
#define KXTJ9_IEL               (1 << 3)
#define KXTJ9_IEA               (1 << 4)
#define KXTJ9_IEN               (1 << 5)
/* INPUT_ABS CONSTANTS */
#define FUZZ                    3
#define FLAT                    3
/* RESUME STATE INDICES */
#define RES_DATA_CTRL           0
#define RES_CTRL_REG1           1
#define RES_INT_CTRL1           2
#define RESUME_ENTRIES          3

/*
 * The following table lists the maximum appropriate poll interval for each
 * available output data rate.
 */
static const struct {
        unsigned int cutoff;
        u8 mask;
} kxtj9_odr_table[] = {
        { 3,    ODR800F },
        { 5,    ODR400F },
        { 10,   ODR200F },
        { 20,   ODR100F },
        { 40,   ODR50F  },
        { 80,   ODR25F  },
        { 0,    ODR12_5F},
};

struct kxtj9_data {
        struct i2c_client *client;
        struct kxtj9_platform_data pdata;
        struct input_dev *input_dev;
#ifdef CONFIG_INPUT_KXTJ9_POLLED_MODE
        struct input_polled_dev *poll_dev;
#endif
        unsigned int last_poll_interval;
        u8 shift;
        u8 ctrl_reg1;
        u8 data_ctrl;
        u8 int_ctrl;
};

static int kxtj9_i2c_read(struct kxtj9_data *tj9, u8 addr, u8 *data, int len)
{
        struct i2c_msg msgs[] = {
                {
                        .addr = tj9->client->addr,
                        .flags = tj9->client->flags,
                        .len = 1,
                        .buf = &addr,
                },
                {
                        .addr = tj9->client->addr,
                        .flags = tj9->client->flags | I2C_M_RD,
                        .len = len,
                        .buf = data,
                },
        };

        return i2c_transfer(tj9->client->adapter, msgs, 2);
}

static void kxtj9_report_acceleration_data(struct kxtj9_data *tj9)
{
        s16 acc_data[3]; /* Data bytes from hardware xL, xH, yL, yH, zL, zH */
        s16 x, y, z;
        int err;

        err = kxtj9_i2c_read(tj9, XOUT_L, (u8 *)acc_data, 6);
        if (err < 0)
                dev_err(&tj9->client->dev, "accelerometer data read failed\n");

        x = le16_to_cpu(acc_data[tj9->pdata.axis_map_x]);
        y = le16_to_cpu(acc_data[tj9->pdata.axis_map_y]);
        z = le16_to_cpu(acc_data[tj9->pdata.axis_map_z]);

        x >>= tj9->shift;
        y >>= tj9->shift;
        z >>= tj9->shift;

        input_report_abs(tj9->input_dev, ABS_X, tj9->pdata.negate_x ? -x : x);
        input_report_abs(tj9->input_dev, ABS_Y, tj9->pdata.negate_y ? -y : y);
        input_report_abs(tj9->input_dev, ABS_Z, tj9->pdata.negate_z ? -z : z);
        input_sync(tj9->input_dev);
}

static irqreturn_t kxtj9_isr(int irq, void *dev)
{
        struct kxtj9_data *tj9 = dev;
        int err;

        /* data ready is the only possible interrupt type */
        kxtj9_report_acceleration_data(tj9);

        err = i2c_smbus_read_byte_data(tj9->client, INT_REL);
        if (err < 0)
                dev_err(&tj9->client->dev,
                        "error clearing interrupt status: %d\n", err);

        return IRQ_HANDLED;
}

static int kxtj9_update_g_range(struct kxtj9_data *tj9, u8 new_g_range)
{
        switch (new_g_range) {
        case KXTJ9_G_2G:
                tj9->shift = 4;
                break;
        case KXTJ9_G_4G:
                tj9->shift = 3;
                break;
        case KXTJ9_G_8G:
                tj9->shift = 2;
                break;
        default:
                return -EINVAL;
        }

        tj9->ctrl_reg1 &= 0xe7;
        tj9->ctrl_reg1 |= new_g_range;

        return 0;
}

static int kxtj9_update_odr(struct kxtj9_data *tj9, unsigned int poll_interval)
{
        int err;
        int i;

        /* Use the lowest ODR that can support the requested poll interval */
        for (i = 0; i < ARRAY_SIZE(kxtj9_odr_table); i++) {
                tj9->data_ctrl = kxtj9_odr_table[i].mask;
                if (poll_interval < kxtj9_odr_table[i].cutoff)
                        break;
        }

        err = i2c_smbus_write_byte_data(tj9->client, CTRL_REG1, 0);
        if (err < 0)
                return err;

        err = i2c_smbus_write_byte_data(tj9->client, DATA_CTRL, tj9->data_ctrl);
        if (err < 0)
                return err;

        err = i2c_smbus_write_byte_data(tj9->client, CTRL_REG1, tj9->ctrl_reg1);
        if (err < 0)
                return err;

        return 0;
}

static int kxtj9_device_power_on(struct kxtj9_data *tj9)
{
        if (tj9->pdata.power_on)
                return tj9->pdata.power_on();

        return 0;
}

static void kxtj9_device_power_off(struct kxtj9_data *tj9)
{
        int err;

        tj9->ctrl_reg1 &= PC1_OFF;
        err = i2c_smbus_write_byte_data(tj9->client, CTRL_REG1, tj9->ctrl_reg1);
        if (err < 0)
                dev_err(&tj9->client->dev, "soft power off failed\n");

        if (tj9->pdata.power_off)
                tj9->pdata.power_off();
}

static int kxtj9_enable(struct kxtj9_data *tj9)
{
        int err;

        err = kxtj9_device_power_on(tj9);
        if (err < 0)
                return err;

        /* ensure that PC1 is cleared before updating control registers */
        err = i2c_smbus_write_byte_data(tj9->client, CTRL_REG1, 0);
        if (err < 0)
                return err;

        /* only write INT_CTRL_REG1 if in irq mode */
        if (tj9->client->irq) {
                err = i2c_smbus_write_byte_data(tj9->client,
                                                INT_CTRL1, tj9->int_ctrl);
                if (err < 0)
                        return err;
        }

        err = kxtj9_update_g_range(tj9, tj9->pdata.g_range);
        if (err < 0)
                return err;

        /* turn on outputs */
        tj9->ctrl_reg1 |= PC1_ON;
        err = i2c_smbus_write_byte_data(tj9->client, CTRL_REG1, tj9->ctrl_reg1);
        if (err < 0)
                return err;

        err = kxtj9_update_odr(tj9, tj9->last_poll_interval);
        if (err < 0)
                return err;

        /* clear initial interrupt if in irq mode */
        if (tj9->client->irq) {
                err = i2c_smbus_read_byte_data(tj9->client, INT_REL);
                if (err < 0) {
                        dev_err(&tj9->client->dev,
                                "error clearing interrupt: %d\n", err);
                        goto fail;
                }
        }

        return 0;

fail:
        kxtj9_device_power_off(tj9);
        return err;
}

static void kxtj9_disable(struct kxtj9_data *tj9)
{
        kxtj9_device_power_off(tj9);
}

static int kxtj9_input_open(struct input_dev *input)
{
        struct kxtj9_data *tj9 = input_get_drvdata(input);

        return kxtj9_enable(tj9);
}

static void kxtj9_input_close(struct input_dev *dev)
{
        struct kxtj9_data *tj9 = input_get_drvdata(dev);

        kxtj9_disable(tj9);
}

static void kxtj9_init_input_device(struct kxtj9_data *tj9,
                                              struct input_dev *input_dev)
{
        __set_bit(EV_ABS, input_dev->evbit);
        input_set_abs_params(input_dev, ABS_X, -G_MAX, G_MAX, FUZZ, FLAT);
        input_set_abs_params(input_dev, ABS_Y, -G_MAX, G_MAX, FUZZ, FLAT);
        input_set_abs_params(input_dev, ABS_Z, -G_MAX, G_MAX, FUZZ, FLAT);

        input_dev->name = "kxtj9_accel";
        input_dev->id.bustype = BUS_I2C;
        input_dev->dev.parent = &tj9->client->dev;
}

static int kxtj9_setup_input_device(struct kxtj9_data *tj9)
{
        struct input_dev *input_dev;
        int err;

        input_dev = input_allocate_device();
        if (!input_dev) {
                dev_err(&tj9->client->dev, "input device allocate failed\n");
                return -ENOMEM;
        }

        tj9->input_dev = input_dev;

        input_dev->open = kxtj9_input_open;
        input_dev->close = kxtj9_input_close;
        input_set_drvdata(input_dev, tj9);

        kxtj9_init_input_device(tj9, input_dev);

        err = input_register_device(tj9->input_dev);
        if (err) {
                dev_err(&tj9->client->dev,
                        "unable to register input polled device %s: %d\n",
                        tj9->input_dev->name, err);
                input_free_device(tj9->input_dev);
                return err;
        }

        return 0;
}

/*
 * When IRQ mode is selected, we need to provide an interface to allow the user
 * to change the output data rate of the part.  For consistency, we are using
 * the set_poll method, which accepts a poll interval in milliseconds, and then
 * calls update_odr() while passing this value as an argument.  In IRQ mode, the
 * data outputs will not be read AT the requested poll interval, rather, the
 * lowest ODR that can support the requested interval.  The client application
 * will be responsible for retrieving data from the input node at the desired
 * interval.
 */

/* Returns currently selected poll interval (in ms) */
static ssize_t kxtj9_get_poll(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct kxtj9_data *tj9 = i2c_get_clientdata(client);

        return sprintf(buf, "%d\n", tj9->last_poll_interval);
}

/* Allow users to select a new poll interval (in ms) */
static ssize_t kxtj9_set_poll(struct device *dev, struct device_attribute *attr,
                                                const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct kxtj9_data *tj9 = i2c_get_clientdata(client);
        struct input_dev *input_dev = tj9->input_dev;
        unsigned int interval;
        int error;

        error = kstrtouint(buf, 10, &interval);
        if (error < 0)
                return error;

        /* Lock the device to prevent races with open/close (and itself) */
        mutex_lock(&input_dev->mutex);

        disable_irq(client->irq);

        /*
         * Set current interval to the greater of the minimum interval or
         * the requested interval
         */
        tj9->last_poll_interval = max(interval, tj9->pdata.min_interval);

        kxtj9_update_odr(tj9, tj9->last_poll_interval);

        enable_irq(client->irq);
        mutex_unlock(&input_dev->mutex);

        return count;
}

static DEVICE_ATTR(poll, S_IRUGO|S_IWUSR, kxtj9_get_poll, kxtj9_set_poll);

static struct attribute *kxtj9_attributes[] = {
        &dev_attr_poll.attr,
        NULL
};

static struct attribute_group kxtj9_attribute_group = {
        .attrs = kxtj9_attributes
};


#ifdef CONFIG_INPUT_KXTJ9_POLLED_MODE
static void kxtj9_poll(struct input_polled_dev *dev)
{
        struct kxtj9_data *tj9 = dev->private;
        unsigned int poll_interval = dev->poll_interval;

        kxtj9_report_acceleration_data(tj9);

        if (poll_interval != tj9->last_poll_interval) {
                kxtj9_update_odr(tj9, poll_interval);
                tj9->last_poll_interval = poll_interval;
        }
}

static void kxtj9_polled_input_open(struct input_polled_dev *dev)
{
        struct kxtj9_data *tj9 = dev->private;

        kxtj9_enable(tj9);
}

static void kxtj9_polled_input_close(struct input_polled_dev *dev)
{
        struct kxtj9_data *tj9 = dev->private;

        kxtj9_disable(tj9);
}

static int kxtj9_setup_polled_device(struct kxtj9_data *tj9)
{
        int err;
        struct input_polled_dev *poll_dev;
        poll_dev = input_allocate_polled_device();

        if (!poll_dev) {
                dev_err(&tj9->client->dev,
                        "Failed to allocate polled device\n");
                return -ENOMEM;
        }

        tj9->poll_dev = poll_dev;
        tj9->input_dev = poll_dev->input;

        poll_dev->private = tj9;
        poll_dev->poll = kxtj9_poll;
        poll_dev->open = kxtj9_polled_input_open;
        poll_dev->close = kxtj9_polled_input_close;

        kxtj9_init_input_device(tj9, poll_dev->input);

        err = input_register_polled_device(poll_dev);
        if (err) {
                dev_err(&tj9->client->dev,
                        "Unable to register polled device, err=%d\n", err);
                input_free_polled_device(poll_dev);
                return err;
        }

        return 0;
}

static void kxtj9_teardown_polled_device(struct kxtj9_data *tj9)
{
        input_unregister_polled_device(tj9->poll_dev);
        input_free_polled_device(tj9->poll_dev);
}

#else

static inline int kxtj9_setup_polled_device(struct kxtj9_data *tj9)
{
        return -ENOSYS;
}

static inline void kxtj9_teardown_polled_device(struct kxtj9_data *tj9)
{
}

#endif

static int kxtj9_verify(struct kxtj9_data *tj9)
{
        int retval;

        retval = kxtj9_device_power_on(tj9);
        if (retval < 0)
                return retval;

        retval = i2c_smbus_read_byte_data(tj9->client, WHO_AM_I);
        if (retval < 0) {
                dev_err(&tj9->client->dev, "read err int source\n");
                goto out;
        }

        retval = (retval != 0x07 && retval != 0x08) ? -EIO : 0;

out:
        kxtj9_device_power_off(tj9);
        return retval;
}

static int kxtj9_probe(struct i2c_client *client,
                                 const struct i2c_device_id *id)
{
        const struct kxtj9_platform_data *pdata =
                        dev_get_platdata(&client->dev);
        struct kxtj9_data *tj9;
        int err;

        if (!i2c_check_functionality(client->adapter,
                                I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE_DATA)) {
                dev_err(&client->dev, "client is not i2c capable\n");
                return -ENXIO;
        }

        if (!pdata) {
                dev_err(&client->dev, "platform data is NULL; exiting\n");
                return -EINVAL;
        }

        tj9 = kzalloc(sizeof(*tj9), GFP_KERNEL);
        if (!tj9) {
                dev_err(&client->dev,
                        "failed to allocate memory for module data\n");
                return -ENOMEM;
        }

        tj9->client = client;
        tj9->pdata = *pdata;

        if (pdata->init) {
                err = pdata->init();
                if (err < 0)
                        goto err_free_mem;
        }

        err = kxtj9_verify(tj9);
        if (err < 0) {
                dev_err(&client->dev, "device not recognized\n");
                goto err_pdata_exit;
        }

        i2c_set_clientdata(client, tj9);

        tj9->ctrl_reg1 = tj9->pdata.res_12bit | tj9->pdata.g_range;
        tj9->last_poll_interval = tj9->pdata.init_interval;

        if (client->irq) {
                /* If in irq mode, populate INT_CTRL_REG1 and enable DRDY. */
                tj9->int_ctrl |= KXTJ9_IEN | KXTJ9_IEA | KXTJ9_IEL;
                tj9->ctrl_reg1 |= DRDYE;

                err = kxtj9_setup_input_device(tj9);
                if (err)
                        goto err_pdata_exit;

                err = request_threaded_irq(client->irq, NULL, kxtj9_isr,
                                           IRQF_TRIGGER_RISING | IRQF_ONESHOT,
                                           "kxtj9-irq", tj9);
                if (err) {
                        dev_err(&client->dev, "request irq failed: %d\n", err);
                        goto err_destroy_input;
                }

                err = sysfs_create_group(&client->dev.kobj, &kxtj9_attribute_group);
                if (err) {
                        dev_err(&client->dev, "sysfs create failed: %d\n", err);
                        goto err_free_irq;
                }

        } else {
                err = kxtj9_setup_polled_device(tj9);
                if (err)
                        goto err_pdata_exit;
        }

        return 0;

err_free_irq:
        free_irq(client->irq, tj9);
err_destroy_input:
        input_unregister_device(tj9->input_dev);
err_pdata_exit:
        if (tj9->pdata.exit)
                tj9->pdata.exit();
err_free_mem:
        kfree(tj9);
        return err;
}

static int kxtj9_remove(struct i2c_client *client)
{
        struct kxtj9_data *tj9 = i2c_get_clientdata(client);

        if (client->irq) {
                sysfs_remove_group(&client->dev.kobj, &kxtj9_attribute_group);
                free_irq(client->irq, tj9);
                input_unregister_device(tj9->input_dev);
        } else {
                kxtj9_teardown_polled_device(tj9);
        }

        if (tj9->pdata.exit)
                tj9->pdata.exit();

        kfree(tj9);

        return 0;
}

static int __maybe_unused kxtj9_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct kxtj9_data *tj9 = i2c_get_clientdata(client);
        struct input_dev *input_dev = tj9->input_dev;

        mutex_lock(&input_dev->mutex);

        if (input_dev->users)
                kxtj9_disable(tj9);

        mutex_unlock(&input_dev->mutex);
        return 0;
}

static int __maybe_unused kxtj9_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct kxtj9_data *tj9 = i2c_get_clientdata(client);
        struct input_dev *input_dev = tj9->input_dev;

        mutex_lock(&input_dev->mutex);

        if (input_dev->users)
                kxtj9_enable(tj9);

        mutex_unlock(&input_dev->mutex);
        return 0;
}

static SIMPLE_DEV_PM_OPS(kxtj9_pm_ops, kxtj9_suspend, kxtj9_resume);

static const struct i2c_device_id kxtj9_id[] = {
        { NAME, 0 },
        { },
};

MODULE_DEVICE_TABLE(i2c, kxtj9_id);

static struct i2c_driver kxtj9_driver = {
        .driver = {
                .name   = NAME,
                .pm     = &kxtj9_pm_ops,
        },
        .probe          = kxtj9_probe,
        .remove         = kxtj9_remove,
        .id_table       = kxtj9_id,
};

module_i2c_driver(kxtj9_driver);

MODULE_DESCRIPTION("KXTJ9 accelerometer driver");
MODULE_AUTHOR("Chris Hudson <chudson@kionix.com>");
MODULE_LICENSE("GPL");