// SPDX-License-Identifier: GPL-2.0
/*
 *  Microchip AT42QT1050 QTouch Sensor Controller
 *
 *  Copyright (C) 2019 Pengutronix, Marco Felsch <kernel@pengutronix.de>
 *
 *  Base on AT42QT1070 driver by:
 *  Bo Shen <voice.shen@atmel.com>
 *  Copyright (C) 2011 Atmel
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>

/* Chip ID */
#define QT1050_CHIP_ID          0x00
#define QT1050_CHIP_ID_VER      0x46

/* Firmware version */
#define QT1050_FW_VERSION       0x01

/* Detection status */
#define QT1050_DET_STATUS       0x02

/* Key status */
#define QT1050_KEY_STATUS       0x03

/* Key Signals */
#define QT1050_KEY_SIGNAL_0_MSB 0x06
#define QT1050_KEY_SIGNAL_0_LSB 0x07
#define QT1050_KEY_SIGNAL_1_MSB 0x08
#define QT1050_KEY_SIGNAL_1_LSB 0x09
#define QT1050_KEY_SIGNAL_2_MSB 0x0c
#define QT1050_KEY_SIGNAL_2_LSB 0x0d
#define QT1050_KEY_SIGNAL_3_MSB 0x0e
#define QT1050_KEY_SIGNAL_3_LSB 0x0f
#define QT1050_KEY_SIGNAL_4_MSB 0x10
#define QT1050_KEY_SIGNAL_4_LSB 0x11

/* Reference data */
#define QT1050_REF_DATA_0_MSB   0x14
#define QT1050_REF_DATA_0_LSB   0x15
#define QT1050_REF_DATA_1_MSB   0x16
#define QT1050_REF_DATA_1_LSB   0x17
#define QT1050_REF_DATA_2_MSB   0x1a
#define QT1050_REF_DATA_2_LSB   0x1b
#define QT1050_REF_DATA_3_MSB   0x1c
#define QT1050_REF_DATA_3_LSB   0x1d
#define QT1050_REF_DATA_4_MSB   0x1e
#define QT1050_REF_DATA_4_LSB   0x1f

/* Negative threshold level */
#define QT1050_NTHR_0           0x21
#define QT1050_NTHR_1           0x22
#define QT1050_NTHR_2           0x24
#define QT1050_NTHR_3           0x25
#define QT1050_NTHR_4           0x26

/* Pulse / Scale  */
#define QT1050_PULSE_SCALE_0    0x28
#define QT1050_PULSE_SCALE_1    0x29
#define QT1050_PULSE_SCALE_2    0x2b
#define QT1050_PULSE_SCALE_3    0x2c
#define QT1050_PULSE_SCALE_4    0x2d

/* Detection integrator counter / AKS */
#define QT1050_DI_AKS_0         0x2f
#define QT1050_DI_AKS_1         0x30
#define QT1050_DI_AKS_2         0x32
#define QT1050_DI_AKS_3         0x33
#define QT1050_DI_AKS_4         0x34

/* Charge Share Delay */
#define QT1050_CSD_0            0x36
#define QT1050_CSD_1            0x37
#define QT1050_CSD_2            0x39
#define QT1050_CSD_3            0x3a
#define QT1050_CSD_4            0x3b

/* Low Power Mode */
#define QT1050_LPMODE           0x3d

/* Calibration and Reset */
#define QT1050_RES_CAL          0x3f
#define QT1050_RES_CAL_RESET            BIT(7)
#define QT1050_RES_CAL_CALIBRATE        BIT(1)

#define QT1050_MAX_KEYS         5
#define QT1050_RESET_TIME       255

struct qt1050_key_regs {
        unsigned int nthr;
        unsigned int pulse_scale;
        unsigned int di_aks;
        unsigned int csd;
};

struct qt1050_key {
        u32 num;
        u32 charge_delay;
        u32 thr_cnt;
        u32 samples;
        u32 scale;
        u32 keycode;
};

struct qt1050_priv {
        struct i2c_client       *client;
        struct input_dev        *input;
        struct regmap           *regmap;
        struct qt1050_key       keys[QT1050_MAX_KEYS];
        unsigned short          keycodes[QT1050_MAX_KEYS];
        u8                      reg_keys;
        u8                      last_keys;
};

static const struct qt1050_key_regs qt1050_key_regs_data[] = {
        {
                .nthr = QT1050_NTHR_0,
                .pulse_scale = QT1050_PULSE_SCALE_0,
                .di_aks = QT1050_DI_AKS_0,
                .csd = QT1050_CSD_0,
        }, {
                .nthr = QT1050_NTHR_1,
                .pulse_scale = QT1050_PULSE_SCALE_1,
                .di_aks = QT1050_DI_AKS_1,
                .csd = QT1050_CSD_1,
        }, {
                .nthr = QT1050_NTHR_2,
                .pulse_scale = QT1050_PULSE_SCALE_2,
                .di_aks = QT1050_DI_AKS_2,
                .csd = QT1050_CSD_2,
        }, {
                .nthr = QT1050_NTHR_3,
                .pulse_scale = QT1050_PULSE_SCALE_3,
                .di_aks = QT1050_DI_AKS_3,
                .csd = QT1050_CSD_3,
        }, {
                .nthr = QT1050_NTHR_4,
                .pulse_scale = QT1050_PULSE_SCALE_4,
                .di_aks = QT1050_DI_AKS_4,
                .csd = QT1050_CSD_4,
        }
};

static bool qt1050_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case QT1050_DET_STATUS:
        case QT1050_KEY_STATUS:
        case QT1050_KEY_SIGNAL_0_MSB:
        case QT1050_KEY_SIGNAL_0_LSB:
        case QT1050_KEY_SIGNAL_1_MSB:
        case QT1050_KEY_SIGNAL_1_LSB:
        case QT1050_KEY_SIGNAL_2_MSB:
        case QT1050_KEY_SIGNAL_2_LSB:
        case QT1050_KEY_SIGNAL_3_MSB:
        case QT1050_KEY_SIGNAL_3_LSB:
        case QT1050_KEY_SIGNAL_4_MSB:
        case QT1050_KEY_SIGNAL_4_LSB:
                return true;
        default:
                return false;
        }
}

static const struct regmap_range qt1050_readable_ranges[] = {
        regmap_reg_range(QT1050_CHIP_ID, QT1050_KEY_STATUS),
        regmap_reg_range(QT1050_KEY_SIGNAL_0_MSB, QT1050_KEY_SIGNAL_1_LSB),
        regmap_reg_range(QT1050_KEY_SIGNAL_2_MSB, QT1050_KEY_SIGNAL_4_LSB),
        regmap_reg_range(QT1050_REF_DATA_0_MSB, QT1050_REF_DATA_1_LSB),
        regmap_reg_range(QT1050_REF_DATA_2_MSB, QT1050_REF_DATA_4_LSB),
        regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
        regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
        regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
        regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
        regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
        regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
        regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
        regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
};

static const struct regmap_access_table qt1050_readable_table = {
        .yes_ranges = qt1050_readable_ranges,
        .n_yes_ranges = ARRAY_SIZE(qt1050_readable_ranges),
};

static const struct regmap_range qt1050_writeable_ranges[] = {
        regmap_reg_range(QT1050_NTHR_0, QT1050_NTHR_1),
        regmap_reg_range(QT1050_NTHR_2, QT1050_NTHR_4),
        regmap_reg_range(QT1050_PULSE_SCALE_0, QT1050_PULSE_SCALE_1),
        regmap_reg_range(QT1050_PULSE_SCALE_2, QT1050_PULSE_SCALE_4),
        regmap_reg_range(QT1050_DI_AKS_0, QT1050_DI_AKS_1),
        regmap_reg_range(QT1050_DI_AKS_2, QT1050_DI_AKS_4),
        regmap_reg_range(QT1050_CSD_0, QT1050_CSD_1),
        regmap_reg_range(QT1050_CSD_2, QT1050_RES_CAL),
};

static const struct regmap_access_table qt1050_writeable_table = {
        .yes_ranges = qt1050_writeable_ranges,
        .n_yes_ranges = ARRAY_SIZE(qt1050_writeable_ranges),
};

static const struct regmap_config qt1050_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = QT1050_RES_CAL,

        .cache_type = REGCACHE_MAPLE,

        .wr_table = &qt1050_writeable_table,
        .rd_table = &qt1050_readable_table,
        .volatile_reg = qt1050_volatile_reg,
};

static bool qt1050_identify(struct qt1050_priv *ts)
{
        unsigned int val;
        int err;

        /* Read Chip ID */
        err = regmap_read(ts->regmap, QT1050_CHIP_ID, &val);
        if (err) {
                dev_err(&ts->client->dev, "Failed to read chip ID: %d\n", err);
                return false;
        }

        if (val != QT1050_CHIP_ID_VER) {
                dev_err(&ts->client->dev, "ID %d not supported\n", val);
                return false;
        }

        /* Read firmware version */
        err = regmap_read(ts->regmap, QT1050_FW_VERSION, &val);
        if (err) {
                dev_err(&ts->client->dev, "could not read the firmware version\n");
                return false;
        }

        dev_info(&ts->client->dev, "AT42QT1050 firmware version %1d.%1d\n",
                 val >> 4, val & 0xf);

        return true;
}

static irqreturn_t qt1050_irq_threaded(int irq, void *dev_id)
{
        struct qt1050_priv *ts = dev_id;
        struct input_dev *input = ts->input;
        unsigned long new_keys, changed;
        unsigned int val;
        int i, err;

        /* Read the detected status register, thus clearing interrupt */
        err = regmap_read(ts->regmap, QT1050_DET_STATUS, &val);
        if (err) {
                dev_err(&ts->client->dev, "Fail to read detection status: %d\n",
                        err);
                return IRQ_NONE;
        }

        /* Read which key changed, keys are not continuous */
        err = regmap_read(ts->regmap, QT1050_KEY_STATUS, &val);
        if (err) {
                dev_err(&ts->client->dev,
                        "Fail to determine the key status: %d\n", err);
                return IRQ_NONE;
        }
        new_keys = (val & 0x70) >> 2 | (val & 0x6) >> 1;
        changed = ts->last_keys ^ new_keys;
        /* Report registered keys only */
        changed &= ts->reg_keys;

        for_each_set_bit(i, &changed, QT1050_MAX_KEYS)
                input_report_key(input, ts->keys[i].keycode,
                                 test_bit(i, &new_keys));

        ts->last_keys = new_keys;
        input_sync(input);

        return IRQ_HANDLED;
}

static const struct qt1050_key_regs *qt1050_get_key_regs(int key_num)
{
        return &qt1050_key_regs_data[key_num];
}

static int qt1050_set_key(struct regmap *map, int number, int on)
{
        const struct qt1050_key_regs *key_regs;

        key_regs = qt1050_get_key_regs(number);

        return regmap_update_bits(map, key_regs->di_aks, 0xfc,
                                  on ? BIT(4) : 0x00);
}

static int qt1050_apply_fw_data(struct qt1050_priv *ts)
{
        struct regmap *map = ts->regmap;
        struct qt1050_key *button = &ts->keys[0];
        const struct qt1050_key_regs *key_regs;
        int i, err;

        /* Disable all keys and enable only the specified ones */
        for (i = 0; i < QT1050_MAX_KEYS; i++) {
                err = qt1050_set_key(map, i, 0);
                if (err)
                        return err;
        }

        for (i = 0; i < QT1050_MAX_KEYS; i++, button++) {
                /* Keep KEY_RESERVED keys off */
                if (button->keycode == KEY_RESERVED)
                        continue;

                err = qt1050_set_key(map, button->num, 1);
                if (err)
                        return err;

                key_regs = qt1050_get_key_regs(button->num);

                err = regmap_write(map, key_regs->pulse_scale,
                                   (button->samples << 4) | (button->scale));
                if (err)
                        return err;
                err = regmap_write(map, key_regs->csd, button->charge_delay);
                if (err)
                        return err;
                err = regmap_write(map, key_regs->nthr, button->thr_cnt);
                if (err)
                        return err;
        }

        return 0;
}

static int qt1050_parse_fw(struct qt1050_priv *ts)
{
        struct device *dev = &ts->client->dev;
        int nbuttons;

        nbuttons = device_get_child_node_count(dev);
        if (nbuttons == 0 || nbuttons > QT1050_MAX_KEYS)
                return -ENODEV;

        device_for_each_child_node_scoped(dev, child) {
                struct qt1050_key button;

                /* Required properties */
                if (fwnode_property_read_u32(child, "linux,code",
                                             &button.keycode)) {
                        dev_err(dev, "Button without keycode\n");
                        return -EINVAL;
                }
                if (button.keycode >= KEY_MAX) {
                        dev_err(dev, "Invalid keycode 0x%x\n",
                                button.keycode);
                        return -EINVAL;
                }

                if (fwnode_property_read_u32(child, "reg",
                                             &button.num)) {
                        dev_err(dev, "Button without pad number\n");
                        return -EINVAL;
                }
                if (button.num < 0 || button.num > QT1050_MAX_KEYS - 1)
                        return -EINVAL;

                ts->reg_keys |= BIT(button.num);

                /* Optional properties */
                if (fwnode_property_read_u32(child,
                                             "microchip,pre-charge-time-ns",
                                             &button.charge_delay)) {
                        button.charge_delay = 0;
                } else {
                        if (button.charge_delay % 2500 == 0)
                                button.charge_delay =
                                        button.charge_delay / 2500;
                        else
                                button.charge_delay = 0;
                }

                if (fwnode_property_read_u32(child, "microchip,average-samples",
                                         &button.samples)) {
                        button.samples = 0;
                } else {
                        if (is_power_of_2(button.samples))
                                button.samples = ilog2(button.samples);
                        else
                                button.samples = 0;
                }

                if (fwnode_property_read_u32(child, "microchip,average-scaling",
                                             &button.scale)) {
                        button.scale = 0;
                } else {
                        if (is_power_of_2(button.scale))
                                button.scale = ilog2(button.scale);
                        else
                                button.scale = 0;

                }

                if (fwnode_property_read_u32(child, "microchip,threshold",
                                         &button.thr_cnt)) {
                        button.thr_cnt = 20;
                } else {
                        if (button.thr_cnt > 255)
                                button.thr_cnt = 20;
                }

                ts->keys[button.num] = button;
        }

        return 0;
}

static int qt1050_probe(struct i2c_client *client)
{
        struct qt1050_priv *ts;
        struct input_dev *input;
        struct device *dev = &client->dev;
        struct regmap *map;
        unsigned int status, i;
        int err;

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

        if (!client->irq) {
                dev_err(dev, "assign a irq line to this device\n");
                return -EINVAL;
        }

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

        input = devm_input_allocate_device(dev);
        if (!input)
                return -ENOMEM;

        map = devm_regmap_init_i2c(client, &qt1050_regmap_config);
        if (IS_ERR(map))
                return PTR_ERR(map);

        ts->client = client;
        ts->input = input;
        ts->regmap = map;

        i2c_set_clientdata(client, ts);

        /* Identify the qt1050 chip */
        if (!qt1050_identify(ts))
                return -ENODEV;

        /* Get pdata */
        err = qt1050_parse_fw(ts);
        if (err) {
                dev_err(dev, "Failed to parse firmware: %d\n", err);
                return err;
        }

        input->name = "AT42QT1050 QTouch Sensor";
        input->dev.parent = &client->dev;
        input->id.bustype = BUS_I2C;

        /* Add the keycode */
        input->keycode = ts->keycodes;
        input->keycodesize = sizeof(ts->keycodes[0]);
        input->keycodemax = QT1050_MAX_KEYS;

        __set_bit(EV_KEY, input->evbit);
        for (i = 0; i < QT1050_MAX_KEYS; i++) {
                ts->keycodes[i] = ts->keys[i].keycode;
                __set_bit(ts->keycodes[i], input->keybit);
        }

        /* Trigger re-calibration */
        err = regmap_update_bits(ts->regmap, QT1050_RES_CAL, 0x7f,
                                 QT1050_RES_CAL_CALIBRATE);
        if (err) {
                dev_err(dev, "Trigger calibration failed: %d\n", err);
                return err;
        }
        err = regmap_read_poll_timeout(ts->regmap, QT1050_DET_STATUS, status,
                                 status >> 7 == 1, 10000, 200000);
        if (err) {
                dev_err(dev, "Calibration failed: %d\n", err);
                return err;
        }

        /* Soft reset to set defaults */
        err = regmap_update_bits(ts->regmap, QT1050_RES_CAL,
                                 QT1050_RES_CAL_RESET, QT1050_RES_CAL_RESET);
        if (err) {
                dev_err(dev, "Trigger soft reset failed: %d\n", err);
                return err;
        }
        msleep(QT1050_RESET_TIME);

        /* Set pdata */
        err = qt1050_apply_fw_data(ts);
        if (err) {
                dev_err(dev, "Failed to set firmware data: %d\n", err);
                return err;
        }

        err = devm_request_threaded_irq(dev, client->irq, NULL,
                                        qt1050_irq_threaded, IRQF_ONESHOT,
                                        "qt1050", ts);
        if (err) {
                dev_err(&client->dev, "Failed to request irq: %d\n", err);
                return err;
        }

        /* Clear #CHANGE line */
        err = regmap_read(ts->regmap, QT1050_DET_STATUS, &status);
        if (err) {
                dev_err(dev, "Failed to clear #CHANGE line level: %d\n", err);
                return err;
        }

        /* Register the input device */
        err = input_register_device(ts->input);
        if (err) {
                dev_err(&client->dev, "Failed to register input device: %d\n",
                        err);
                return err;
        }

        return 0;
}

static int qt1050_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct qt1050_priv *ts = i2c_get_clientdata(client);

        disable_irq(client->irq);

        /*
         * Set measurement interval to 1s (125 x 8ms) if wakeup is allowed
         * else turn off. The 1s interval seems to be a good compromise between
         * low power and response time.
         */
        return regmap_write(ts->regmap, QT1050_LPMODE,
                            device_may_wakeup(dev) ? 125 : 0);
}

static int qt1050_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct qt1050_priv *ts = i2c_get_clientdata(client);

        enable_irq(client->irq);

        /* Set measurement interval back to 16ms (2 x 8ms) */
        return regmap_write(ts->regmap, QT1050_LPMODE, 2);
}

static DEFINE_SIMPLE_DEV_PM_OPS(qt1050_pm_ops, qt1050_suspend, qt1050_resume);

static const struct of_device_id __maybe_unused qt1050_of_match[] = {
        { .compatible = "microchip,qt1050", },
        { },
};
MODULE_DEVICE_TABLE(of, qt1050_of_match);

static struct i2c_driver qt1050_driver = {
        .driver = {
                .name = "qt1050",
                .of_match_table = of_match_ptr(qt1050_of_match),
                .pm = pm_sleep_ptr(&qt1050_pm_ops),
        },
        .probe = qt1050_probe,
};

module_i2c_driver(qt1050_driver);

MODULE_AUTHOR("Marco Felsch <kernel@pengutronix.de");
MODULE_DESCRIPTION("Driver for AT42QT1050 QTouch sensor");
MODULE_LICENSE("GPL v2");