// SPDX-License-Identifier: GPL-2.0
/*
 * Rohm BU21029 touchscreen controller driver
 *
 * Copyright (C) 2015-2018 Bosch Sicherheitssysteme GmbH
 *
 * 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/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/input/touchscreen.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/timer.h>

/*
 * HW_ID1 Register (PAGE=0, ADDR=0x0E, Reset value=0x02, Read only)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |                                 HW_IDH                                |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * HW_ID2 Register (PAGE=0, ADDR=0x0F, Reset value=0x29, Read only)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |                                 HW_IDL                                |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * HW_IDH: high 8bits of IC's ID
 * HW_IDL: low  8bits of IC's ID
 */
#define BU21029_HWID_REG        (0x0E << 3)
#define SUPPORTED_HWID          0x0229

/*
 * CFR0 Register (PAGE=0, ADDR=0x00, Reset value=0x20)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   0    |   0    |  CALIB |  INTRM |   0    |   0    |   0    |   0    |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * CALIB: 0 = not to use calibration result (*)
 *        1 = use calibration result
 * INTRM: 0 = INT output depend on "pen down" (*)
 *        1 = INT output always "0"
 */
#define BU21029_CFR0_REG        (0x00 << 3)
#define CFR0_VALUE              0x00

/*
 * CFR1 Register (PAGE=0, ADDR=0x01, Reset value=0xA6)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |  MAV   |         AVE[2:0]         |   0    |         SMPL[2:0]        |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * MAV:  0 = median average filter off
 *       1 = median average filter on (*)
 * AVE:  AVE+1 = number of average samples for MAV,
 *               if AVE>SMPL, then AVE=SMPL (=3)
 * SMPL: SMPL+1 = number of conversion samples for MAV (=7)
 */
#define BU21029_CFR1_REG        (0x01 << 3)
#define CFR1_VALUE              0xA6

/*
 * CFR2 Register (PAGE=0, ADDR=0x02, Reset value=0x04)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |          INTVL_TIME[3:0]          |          TIME_ST_ADC[3:0]         |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * INTVL_TIME: waiting time between completion of conversion
 *             and start of next conversion, only usable in
 *             autoscan mode (=20.480ms)
 * TIME_ST_ADC: waiting time between application of voltage
 *              to panel and start of A/D conversion (=100us)
 */
#define BU21029_CFR2_REG        (0x02 << 3)
#define CFR2_VALUE              0xC9

/*
 * CFR3 Register (PAGE=0, ADDR=0x0B, Reset value=0x72)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |  RM8   | STRETCH|  PU90K |  DUAL  |           PIDAC_OFS[3:0]          |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * RM8: 0 = coordinate resolution is 12bit (*)
 *      1 = coordinate resolution is 8bit
 * STRETCH: 0 = SCL_STRETCH function off
 *          1 = SCL_STRETCH function on (*)
 * PU90K: 0 = internal pull-up resistance for touch detection is ~50kohms (*)
 *        1 = internal pull-up resistance for touch detection is ~90kohms
 * DUAL: 0 = dual touch detection off (*)
 *       1 = dual touch detection on
 * PIDAC_OFS: dual touch detection circuit adjustment, it is not necessary
 *            to change this from initial value
 */
#define BU21029_CFR3_REG        (0x0B << 3)
#define CFR3_VALUE              0x42

/*
 * LDO Register (PAGE=0, ADDR=0x0C, Reset value=0x00)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   0    |         PVDD[2:0]        |   0    |         AVDD[2:0]        |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * PVDD: output voltage of panel output regulator (=2.000V)
 * AVDD: output voltage of analog circuit regulator (=2.000V)
 */
#define BU21029_LDO_REG         (0x0C << 3)
#define LDO_VALUE               0x77

/*
 * Serial Interface Command Byte 1 (CID=1)
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   D7   |   D6   |   D5   |   D4   |   D3   |   D2   |   D1   |   D0   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * |   1    |                 CF                |  CMSK  |  PDM   |  STP   |
 * +--------+--------+--------+--------+--------+--------+--------+--------+
 * CF: conversion function, see table 3 in datasheet p6 (=0000, automatic scan)
 * CMSK: 0 = executes convert function (*)
 *       1 = reads the convert result
 * PDM: 0 = power down after convert function stops (*)
 *      1 = keep power on after convert function stops
 * STP: 1 = abort current conversion and power down, set to "0" automatically
 */
#define BU21029_AUTOSCAN        0x80

/*
 * The timeout value needs to be larger than INTVL_TIME + tConv4 (sample and
 * conversion time), where tConv4 is calculated by formula:
 * tPON + tDLY1 + (tTIME_ST_ADC + (tADC * tSMPL) * 2 + tDLY2) * 3
 * see figure 8 in datasheet p15 for details of each field.
 */
#define PEN_UP_TIMEOUT_MS       50

#define STOP_DELAY_MIN_US       50
#define STOP_DELAY_MAX_US       1000
#define START_DELAY_MS          2
#define BUF_LEN                 8
#define SCALE_12BIT             (1 << 12)
#define MAX_12BIT               ((1 << 12) - 1)
#define DRIVER_NAME             "bu21029"

struct bu21029_ts_data {
        struct i2c_client               *client;
        struct input_dev                *in_dev;
        struct timer_list               timer;
        struct regulator                *vdd;
        struct gpio_desc                *reset_gpios;
        u32                             x_plate_ohms;
        struct touchscreen_properties   prop;
};

static void bu21029_touch_report(struct bu21029_ts_data *bu21029, const u8 *buf)
{
        u16 x, y, z1, z2;
        u32 rz;
        s32 max_pressure = input_abs_get_max(bu21029->in_dev, ABS_PRESSURE);

        /*
         * compose upper 8 and lower 4 bits into a 12bit value:
         * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
         * |            ByteH              |            ByteL              |
         * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
         * |b07|b06|b05|b04|b03|b02|b01|b00|b07|b06|b05|b04|b03|b02|b01|b00|
         * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
         * |v11|v10|v09|v08|v07|v06|v05|v04|v03|v02|v01|v00| 0 | 0 | 0 | 0 |
         * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
         */
        x  = (buf[0] << 4) | (buf[1] >> 4);
        y  = (buf[2] << 4) | (buf[3] >> 4);
        z1 = (buf[4] << 4) | (buf[5] >> 4);
        z2 = (buf[6] << 4) | (buf[7] >> 4);

        if (z1 && z2) {
                /*
                 * calculate Rz (pressure resistance value) by equation:
                 * Rz = Rx * (x/Q) * ((z2/z1) - 1), where
                 * Rx is x-plate resistance,
                 * Q  is the touch screen resolution (8bit = 256, 12bit = 4096)
                 * x, z1, z2 are the measured positions.
                 */
                rz  = z2 - z1;
                rz *= x;
                rz *= bu21029->x_plate_ohms;
                rz /= z1;
                rz  = DIV_ROUND_CLOSEST(rz, SCALE_12BIT);
                if (rz <= max_pressure) {
                        touchscreen_report_pos(bu21029->in_dev, &bu21029->prop,
                                               x, y, false);
                        input_report_abs(bu21029->in_dev, ABS_PRESSURE,
                                         max_pressure - rz);
                        input_report_key(bu21029->in_dev, BTN_TOUCH, 1);
                        input_sync(bu21029->in_dev);
                }
        }
}

static void bu21029_touch_release(struct timer_list *t)
{
        struct bu21029_ts_data *bu21029 = timer_container_of(bu21029, t,
                                                             timer);

        input_report_abs(bu21029->in_dev, ABS_PRESSURE, 0);
        input_report_key(bu21029->in_dev, BTN_TOUCH, 0);
        input_sync(bu21029->in_dev);
}

static irqreturn_t bu21029_touch_soft_irq(int irq, void *data)
{
        struct bu21029_ts_data *bu21029 = data;
        u8 buf[BUF_LEN];
        int error;

        /*
         * Read touch data and deassert interrupt (will assert again after
         * INTVL_TIME + tConv4 for continuous touch)
         */
        error = i2c_smbus_read_i2c_block_data(bu21029->client, BU21029_AUTOSCAN,
                                              sizeof(buf), buf);
        if (error < 0)
                goto out;

        bu21029_touch_report(bu21029, buf);

        /* reset timer for pen up detection */
        mod_timer(&bu21029->timer,
                  jiffies + msecs_to_jiffies(PEN_UP_TIMEOUT_MS));

out:
        return IRQ_HANDLED;
}

static void bu21029_put_chip_in_reset(struct bu21029_ts_data *bu21029)
{
        if (bu21029->reset_gpios) {
                gpiod_set_value_cansleep(bu21029->reset_gpios, 1);
                usleep_range(STOP_DELAY_MIN_US, STOP_DELAY_MAX_US);
        }
}

static int bu21029_start_chip(struct input_dev *dev)
{
        struct bu21029_ts_data *bu21029 = input_get_drvdata(dev);
        struct i2c_client *i2c = bu21029->client;
        struct {
                u8 reg;
                u8 value;
        } init_table[] = {
                {BU21029_CFR0_REG, CFR0_VALUE},
                {BU21029_CFR1_REG, CFR1_VALUE},
                {BU21029_CFR2_REG, CFR2_VALUE},
                {BU21029_CFR3_REG, CFR3_VALUE},
                {BU21029_LDO_REG,  LDO_VALUE}
        };
        int error, i;
        __be16 hwid;

        error = regulator_enable(bu21029->vdd);
        if (error) {
                dev_err(&i2c->dev, "failed to power up chip: %d", error);
                return error;
        }

        /* take chip out of reset */
        if (bu21029->reset_gpios) {
                gpiod_set_value_cansleep(bu21029->reset_gpios, 0);
                msleep(START_DELAY_MS);
        }

        error = i2c_smbus_read_i2c_block_data(i2c, BU21029_HWID_REG,
                                              sizeof(hwid), (u8 *)&hwid);
        if (error < 0) {
                dev_err(&i2c->dev, "failed to read HW ID\n");
                goto err_out;
        }

        if (be16_to_cpu(hwid) != SUPPORTED_HWID) {
                dev_err(&i2c->dev,
                        "unsupported HW ID 0x%x\n", be16_to_cpu(hwid));
                error = -ENODEV;
                goto err_out;
        }

        for (i = 0; i < ARRAY_SIZE(init_table); ++i) {
                error = i2c_smbus_write_byte_data(i2c,
                                                  init_table[i].reg,
                                                  init_table[i].value);
                if (error < 0) {
                        dev_err(&i2c->dev,
                                "failed to write %#02x to register %#02x: %d\n",
                                init_table[i].value, init_table[i].reg,
                                error);
                        goto err_out;
                }
        }

        error = i2c_smbus_write_byte(i2c, BU21029_AUTOSCAN);
        if (error < 0) {
                dev_err(&i2c->dev, "failed to start autoscan\n");
                goto err_out;
        }

        enable_irq(bu21029->client->irq);
        return 0;

err_out:
        bu21029_put_chip_in_reset(bu21029);
        regulator_disable(bu21029->vdd);
        return error;
}

static void bu21029_stop_chip(struct input_dev *dev)
{
        struct bu21029_ts_data *bu21029 = input_get_drvdata(dev);

        disable_irq(bu21029->client->irq);
        timer_delete_sync(&bu21029->timer);

        bu21029_put_chip_in_reset(bu21029);
        regulator_disable(bu21029->vdd);
}

static int bu21029_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct bu21029_ts_data *bu21029;
        struct input_dev *in_dev;
        int error;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_WRITE_BYTE |
                                     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
                                     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
                dev_err(dev, "i2c functionality support is not sufficient\n");
                return -EIO;
        }

        bu21029 = devm_kzalloc(dev, sizeof(*bu21029), GFP_KERNEL);
        if (!bu21029)
                return -ENOMEM;

        error = device_property_read_u32(dev, "rohm,x-plate-ohms", &bu21029->x_plate_ohms);
        if (error) {
                dev_err(dev, "invalid 'x-plate-ohms' supplied: %d\n", error);
                return error;
        }

        bu21029->vdd = devm_regulator_get(dev, "vdd");
        if (IS_ERR(bu21029->vdd))
                return dev_err_probe(dev, PTR_ERR(bu21029->vdd),
                                     "failed to acquire 'vdd' supply\n");

        bu21029->reset_gpios = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(bu21029->reset_gpios))
                return dev_err_probe(dev, PTR_ERR(bu21029->reset_gpios),
                                     "failed to acquire 'reset' gpio\n");

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

        bu21029->client = client;
        bu21029->in_dev = in_dev;
        timer_setup(&bu21029->timer, bu21029_touch_release, 0);

        in_dev->name            = DRIVER_NAME;
        in_dev->id.bustype      = BUS_I2C;
        in_dev->open            = bu21029_start_chip;
        in_dev->close           = bu21029_stop_chip;

        input_set_capability(in_dev, EV_KEY, BTN_TOUCH);
        input_set_abs_params(in_dev, ABS_X, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(in_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(in_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
        touchscreen_parse_properties(in_dev, false, &bu21029->prop);

        input_set_drvdata(in_dev, bu21029);

        error = devm_request_threaded_irq(dev, client->irq, NULL,
                                          bu21029_touch_soft_irq,
                                          IRQF_ONESHOT | IRQF_NO_AUTOEN,
                                          DRIVER_NAME, bu21029);
        if (error) {
                dev_err(dev, "unable to request touch irq: %d\n", error);
                return error;
        }

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

        i2c_set_clientdata(client, bu21029);

        return 0;
}

static int bu21029_suspend(struct device *dev)
{
        struct i2c_client *i2c = to_i2c_client(dev);
        struct bu21029_ts_data *bu21029 = i2c_get_clientdata(i2c);

        if (!device_may_wakeup(dev)) {
                mutex_lock(&bu21029->in_dev->mutex);
                if (input_device_enabled(bu21029->in_dev))
                        bu21029_stop_chip(bu21029->in_dev);
                mutex_unlock(&bu21029->in_dev->mutex);
        }

        return 0;
}

static int bu21029_resume(struct device *dev)
{
        struct i2c_client *i2c = to_i2c_client(dev);
        struct bu21029_ts_data *bu21029 = i2c_get_clientdata(i2c);

        if (!device_may_wakeup(dev)) {
                mutex_lock(&bu21029->in_dev->mutex);
                if (input_device_enabled(bu21029->in_dev))
                        bu21029_start_chip(bu21029->in_dev);
                mutex_unlock(&bu21029->in_dev->mutex);
        }

        return 0;
}
static DEFINE_SIMPLE_DEV_PM_OPS(bu21029_pm_ops, bu21029_suspend, bu21029_resume);

static const struct i2c_device_id bu21029_ids[] = {
        { DRIVER_NAME },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, bu21029_ids);

#ifdef CONFIG_OF
static const struct of_device_id bu21029_of_ids[] = {
        { .compatible = "rohm,bu21029" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, bu21029_of_ids);
#endif

static struct i2c_driver bu21029_driver = {
        .driver = {
                .name           = DRIVER_NAME,
                .of_match_table = of_match_ptr(bu21029_of_ids),
                .pm             = pm_sleep_ptr(&bu21029_pm_ops),
        },
        .id_table       = bu21029_ids,
        .probe          = bu21029_probe,
};
module_i2c_driver(bu21029_driver);

MODULE_AUTHOR("Zhu Yi <yi.zhu5@cn.bosch.com>");
MODULE_DESCRIPTION("Rohm BU21029 touchscreen controller driver");
MODULE_LICENSE("GPL v2");