// SPDX-License-Identifier: GPL-2.0+
/*
 * Azoteq IQS550/572/525 Trackpad/Touchscreen Controller
 *
 * Copyright (C) 2018
 * Author: Jeff LaBundy <jeff@labundy.com>
 *
 * These devices require firmware exported from a PC-based configuration tool
 * made available by the vendor. Firmware files may be pushed to the device's
 * nonvolatile memory by writing the filename to the 'fw_file' sysfs control.
 *
 * Link to PC-based configuration tool and data sheet: http://www.azoteq.com/
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/firmware.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/input/touchscreen.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <asm/unaligned.h>

#define IQS5XX_FW_FILE_LEN      64
#define IQS5XX_NUM_RETRIES      10
#define IQS5XX_NUM_POINTS       256
#define IQS5XX_NUM_CONTACTS     5
#define IQS5XX_WR_BYTES_MAX     2

#define IQS5XX_PROD_NUM_IQS550  40
#define IQS5XX_PROD_NUM_IQS572  58
#define IQS5XX_PROD_NUM_IQS525  52
#define IQS5XX_PROJ_NUM_A000    0
#define IQS5XX_PROJ_NUM_B000    15
#define IQS5XX_MAJOR_VER_MIN    2

#define IQS5XX_RESUME           0x00
#define IQS5XX_SUSPEND          0x01

#define IQS5XX_SW_INPUT_EVENT   0x10
#define IQS5XX_SETUP_COMPLETE   0x40
#define IQS5XX_EVENT_MODE       0x01
#define IQS5XX_TP_EVENT         0x04

#define IQS5XX_FLIP_X           0x01
#define IQS5XX_FLIP_Y           0x02
#define IQS5XX_SWITCH_XY_AXIS   0x04

#define IQS5XX_PROD_NUM         0x0000
#define IQS5XX_ABS_X            0x0016
#define IQS5XX_ABS_Y            0x0018
#define IQS5XX_SYS_CTRL0        0x0431
#define IQS5XX_SYS_CTRL1        0x0432
#define IQS5XX_SYS_CFG0         0x058E
#define IQS5XX_SYS_CFG1         0x058F
#define IQS5XX_TOTAL_RX         0x063D
#define IQS5XX_TOTAL_TX         0x063E
#define IQS5XX_XY_CFG0          0x0669
#define IQS5XX_X_RES            0x066E
#define IQS5XX_Y_RES            0x0670
#define IQS5XX_CHKSM            0x83C0
#define IQS5XX_APP              0x8400
#define IQS5XX_CSTM             0xBE00
#define IQS5XX_PMAP_END         0xBFFF
#define IQS5XX_END_COMM         0xEEEE

#define IQS5XX_CHKSM_LEN        (IQS5XX_APP - IQS5XX_CHKSM)
#define IQS5XX_APP_LEN          (IQS5XX_CSTM - IQS5XX_APP)
#define IQS5XX_CSTM_LEN         (IQS5XX_PMAP_END + 1 - IQS5XX_CSTM)
#define IQS5XX_PMAP_LEN         (IQS5XX_PMAP_END + 1 - IQS5XX_CHKSM)

#define IQS5XX_REC_HDR_LEN      4
#define IQS5XX_REC_LEN_MAX      255
#define IQS5XX_REC_TYPE_DATA    0x00
#define IQS5XX_REC_TYPE_EOF     0x01

#define IQS5XX_BL_ADDR_MASK     0x40
#define IQS5XX_BL_CMD_VER       0x00
#define IQS5XX_BL_CMD_READ      0x01
#define IQS5XX_BL_CMD_EXEC      0x02
#define IQS5XX_BL_CMD_CRC       0x03
#define IQS5XX_BL_BLK_LEN_MAX   64
#define IQS5XX_BL_ID            0x0200
#define IQS5XX_BL_STATUS_RESET  0x00
#define IQS5XX_BL_STATUS_AVAIL  0xA5
#define IQS5XX_BL_STATUS_NONE   0xEE
#define IQS5XX_BL_CRC_PASS      0x00
#define IQS5XX_BL_CRC_FAIL      0x01
#define IQS5XX_BL_ATTEMPTS      3

struct iqs5xx_private {
        struct i2c_client *client;
        struct input_dev *input;
        struct gpio_desc *reset_gpio;
        struct mutex lock;
        u8 bl_status;
};

struct iqs5xx_dev_id_info {
        __be16 prod_num;
        __be16 proj_num;
        u8 major_ver;
        u8 minor_ver;
        u8 bl_status;
} __packed;

struct iqs5xx_ihex_rec {
        char start;
        char len[2];
        char addr[4];
        char type[2];
        char data[2];
} __packed;

struct iqs5xx_touch_data {
        __be16 abs_x;
        __be16 abs_y;
        __be16 strength;
        u8 area;
} __packed;

static int iqs5xx_read_burst(struct i2c_client *client,
                             u16 reg, void *val, u16 len)
{
        __be16 reg_buf = cpu_to_be16(reg);
        int ret, i;
        struct i2c_msg msg[] = {
                {
                        .addr = client->addr,
                        .flags = 0,
                        .len = sizeof(reg_buf),
                        .buf = (u8 *)&reg_buf,
                },
                {
                        .addr = client->addr,
                        .flags = I2C_M_RD,
                        .len = len,
                        .buf = (u8 *)val,
                },
        };

        /*
         * The first addressing attempt outside of a communication window fails
         * and must be retried, after which the device clock stretches until it
         * is available.
         */
        for (i = 0; i < IQS5XX_NUM_RETRIES; i++) {
                ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
                if (ret == ARRAY_SIZE(msg))
                        return 0;

                usleep_range(200, 300);
        }

        if (ret >= 0)
                ret = -EIO;

        dev_err(&client->dev, "Failed to read from address 0x%04X: %d\n",
                reg, ret);

        return ret;
}

static int iqs5xx_read_word(struct i2c_client *client, u16 reg, u16 *val)
{
        __be16 val_buf;
        int error;

        error = iqs5xx_read_burst(client, reg, &val_buf, sizeof(val_buf));
        if (error)
                return error;

        *val = be16_to_cpu(val_buf);

        return 0;
}

static int iqs5xx_read_byte(struct i2c_client *client, u16 reg, u8 *val)
{
        return iqs5xx_read_burst(client, reg, val, sizeof(*val));
}

static int iqs5xx_write_burst(struct i2c_client *client,
                              u16 reg, const void *val, u16 len)
{
        int ret, i;
        u16 mlen = sizeof(reg) + len;
        u8 mbuf[sizeof(reg) + IQS5XX_WR_BYTES_MAX];

        if (len > IQS5XX_WR_BYTES_MAX)
                return -EINVAL;

        put_unaligned_be16(reg, mbuf);
        memcpy(mbuf + sizeof(reg), val, len);

        /*
         * The first addressing attempt outside of a communication window fails
         * and must be retried, after which the device clock stretches until it
         * is available.
         */
        for (i = 0; i < IQS5XX_NUM_RETRIES; i++) {
                ret = i2c_master_send(client, mbuf, mlen);
                if (ret == mlen)
                        return 0;

                usleep_range(200, 300);
        }

        if (ret >= 0)
                ret = -EIO;

        dev_err(&client->dev, "Failed to write to address 0x%04X: %d\n",
                reg, ret);

        return ret;
}

static int iqs5xx_write_word(struct i2c_client *client, u16 reg, u16 val)
{
        __be16 val_buf = cpu_to_be16(val);

        return iqs5xx_write_burst(client, reg, &val_buf, sizeof(val_buf));
}

static int iqs5xx_write_byte(struct i2c_client *client, u16 reg, u8 val)
{
        return iqs5xx_write_burst(client, reg, &val, sizeof(val));
}

static void iqs5xx_reset(struct i2c_client *client)
{
        struct iqs5xx_private *iqs5xx = i2c_get_clientdata(client);

        gpiod_set_value_cansleep(iqs5xx->reset_gpio, 1);
        usleep_range(200, 300);

        gpiod_set_value_cansleep(iqs5xx->reset_gpio, 0);
}

static int iqs5xx_bl_cmd(struct i2c_client *client, u8 bl_cmd, u16 bl_addr)
{
        struct i2c_msg msg;
        int ret;
        u8 mbuf[sizeof(bl_cmd) + sizeof(bl_addr)];

        msg.addr = client->addr ^ IQS5XX_BL_ADDR_MASK;
        msg.flags = 0;
        msg.len = sizeof(bl_cmd);
        msg.buf = mbuf;

        *mbuf = bl_cmd;

        switch (bl_cmd) {
        case IQS5XX_BL_CMD_VER:
        case IQS5XX_BL_CMD_CRC:
        case IQS5XX_BL_CMD_EXEC:
                break;
        case IQS5XX_BL_CMD_READ:
                msg.len += sizeof(bl_addr);
                put_unaligned_be16(bl_addr, mbuf + sizeof(bl_cmd));
                break;
        default:
                return -EINVAL;
        }

        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret != 1)
                goto msg_fail;

        switch (bl_cmd) {
        case IQS5XX_BL_CMD_VER:
                msg.len = sizeof(u16);
                break;
        case IQS5XX_BL_CMD_CRC:
                msg.len = sizeof(u8);
                /*
                 * This delay saves the bus controller the trouble of having to
                 * tolerate a relatively long clock-stretching period while the
                 * CRC is calculated.
                 */
                msleep(50);
                break;
        case IQS5XX_BL_CMD_EXEC:
                usleep_range(10000, 10100);
                /* fall through */
        default:
                return 0;
        }

        msg.flags = I2C_M_RD;

        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret != 1)
                goto msg_fail;

        if (bl_cmd == IQS5XX_BL_CMD_VER &&
            get_unaligned_be16(mbuf) != IQS5XX_BL_ID) {
                dev_err(&client->dev, "Unrecognized bootloader ID: 0x%04X\n",
                        get_unaligned_be16(mbuf));
                return -EINVAL;
        }

        if (bl_cmd == IQS5XX_BL_CMD_CRC && *mbuf != IQS5XX_BL_CRC_PASS) {
                dev_err(&client->dev, "Bootloader CRC failed\n");
                return -EIO;
        }

        return 0;

msg_fail:
        if (ret >= 0)
                ret = -EIO;

        if (bl_cmd != IQS5XX_BL_CMD_VER)
                dev_err(&client->dev,
                        "Unsuccessful bootloader command 0x%02X: %d\n",
                        bl_cmd, ret);

        return ret;
}

static int iqs5xx_bl_open(struct i2c_client *client)
{
        int error, i, j;

        /*
         * The device opens a bootloader polling window for 2 ms following the
         * release of reset. If the host cannot establish communication during
         * this time frame, it must cycle reset again.
         */
        for (i = 0; i < IQS5XX_BL_ATTEMPTS; i++) {
                iqs5xx_reset(client);

                for (j = 0; j < IQS5XX_NUM_RETRIES; j++) {
                        error = iqs5xx_bl_cmd(client, IQS5XX_BL_CMD_VER, 0);
                        if (!error || error == -EINVAL)
                                return error;
                }
        }

        dev_err(&client->dev, "Failed to open bootloader: %d\n", error);

        return error;
}

static int iqs5xx_bl_write(struct i2c_client *client,
                           u16 bl_addr, u8 *pmap_data, u16 pmap_len)
{
        struct i2c_msg msg;
        int ret, i;
        u8 mbuf[sizeof(bl_addr) + IQS5XX_BL_BLK_LEN_MAX];

        if (pmap_len % IQS5XX_BL_BLK_LEN_MAX)
                return -EINVAL;

        msg.addr = client->addr ^ IQS5XX_BL_ADDR_MASK;
        msg.flags = 0;
        msg.len = sizeof(mbuf);
        msg.buf = mbuf;

        for (i = 0; i < pmap_len; i += IQS5XX_BL_BLK_LEN_MAX) {
                put_unaligned_be16(bl_addr + i, mbuf);
                memcpy(mbuf + sizeof(bl_addr), pmap_data + i,
                       sizeof(mbuf) - sizeof(bl_addr));

                ret = i2c_transfer(client->adapter, &msg, 1);
                if (ret != 1)
                        goto msg_fail;

                usleep_range(10000, 10100);
        }

        return 0;

msg_fail:
        if (ret >= 0)
                ret = -EIO;

        dev_err(&client->dev, "Failed to write block at address 0x%04X: %d\n",
                bl_addr + i, ret);

        return ret;
}

static int iqs5xx_bl_verify(struct i2c_client *client,
                            u16 bl_addr, u8 *pmap_data, u16 pmap_len)
{
        struct i2c_msg msg;
        int ret, i;
        u8 bl_data[IQS5XX_BL_BLK_LEN_MAX];

        if (pmap_len % IQS5XX_BL_BLK_LEN_MAX)
                return -EINVAL;

        msg.addr = client->addr ^ IQS5XX_BL_ADDR_MASK;
        msg.flags = I2C_M_RD;
        msg.len = sizeof(bl_data);
        msg.buf = bl_data;

        for (i = 0; i < pmap_len; i += IQS5XX_BL_BLK_LEN_MAX) {
                ret = iqs5xx_bl_cmd(client, IQS5XX_BL_CMD_READ, bl_addr + i);
                if (ret)
                        return ret;

                ret = i2c_transfer(client->adapter, &msg, 1);
                if (ret != 1)
                        goto msg_fail;

                if (memcmp(bl_data, pmap_data + i, sizeof(bl_data))) {
                        dev_err(&client->dev,
                                "Failed to verify block at address 0x%04X\n",
                                bl_addr + i);
                        return -EIO;
                }
        }

        return 0;

msg_fail:
        if (ret >= 0)
                ret = -EIO;

        dev_err(&client->dev, "Failed to read block at address 0x%04X: %d\n",
                bl_addr + i, ret);

        return ret;
}

static int iqs5xx_set_state(struct i2c_client *client, u8 state)
{
        struct iqs5xx_private *iqs5xx = i2c_get_clientdata(client);
        int error1, error2;

        if (iqs5xx->bl_status == IQS5XX_BL_STATUS_RESET)
                return 0;

        mutex_lock(&iqs5xx->lock);

        /*
         * Addressing the device outside of a communication window prompts it
         * to assert the RDY output, so disable the interrupt line to prevent
         * the handler from servicing a false interrupt.
         */
        disable_irq(client->irq);

        error1 = iqs5xx_write_byte(client, IQS5XX_SYS_CTRL1, state);
        error2 = iqs5xx_write_byte(client, IQS5XX_END_COMM, 0);

        usleep_range(50, 100);
        enable_irq(client->irq);

        mutex_unlock(&iqs5xx->lock);

        if (error1)
                return error1;

        return error2;
}

static int iqs5xx_open(struct input_dev *input)
{
        struct iqs5xx_private *iqs5xx = input_get_drvdata(input);

        return iqs5xx_set_state(iqs5xx->client, IQS5XX_RESUME);
}

static void iqs5xx_close(struct input_dev *input)
{
        struct iqs5xx_private *iqs5xx = input_get_drvdata(input);

        iqs5xx_set_state(iqs5xx->client, IQS5XX_SUSPEND);
}

static int iqs5xx_axis_init(struct i2c_client *client)
{
        struct iqs5xx_private *iqs5xx = i2c_get_clientdata(client);
        struct touchscreen_properties prop;
        struct input_dev *input;
        int error;
        u16 max_x, max_x_hw;
        u16 max_y, max_y_hw;
        u8 val;

        if (!iqs5xx->input) {
                input = devm_input_allocate_device(&client->dev);
                if (!input)
                        return -ENOMEM;

                input->name = client->name;
                input->id.bustype = BUS_I2C;
                input->open = iqs5xx_open;
                input->close = iqs5xx_close;

                input_set_capability(input, EV_ABS, ABS_MT_POSITION_X);
                input_set_capability(input, EV_ABS, ABS_MT_POSITION_Y);
                input_set_capability(input, EV_ABS, ABS_MT_PRESSURE);

                input_set_drvdata(input, iqs5xx);
                iqs5xx->input = input;
        }

        touchscreen_parse_properties(iqs5xx->input, true, &prop);

        error = iqs5xx_read_byte(client, IQS5XX_TOTAL_RX, &val);
        if (error)
                return error;
        max_x_hw = (val - 1) * IQS5XX_NUM_POINTS;

        error = iqs5xx_read_byte(client, IQS5XX_TOTAL_TX, &val);
        if (error)
                return error;
        max_y_hw = (val - 1) * IQS5XX_NUM_POINTS;

        error = iqs5xx_read_byte(client, IQS5XX_XY_CFG0, &val);
        if (error)
                return error;

        if (val & IQS5XX_SWITCH_XY_AXIS)
                swap(max_x_hw, max_y_hw);

        if (prop.swap_x_y)
                val ^= IQS5XX_SWITCH_XY_AXIS;

        if (prop.invert_x)
                val ^= prop.swap_x_y ? IQS5XX_FLIP_Y : IQS5XX_FLIP_X;

        if (prop.invert_y)
                val ^= prop.swap_x_y ? IQS5XX_FLIP_X : IQS5XX_FLIP_Y;

        error = iqs5xx_write_byte(client, IQS5XX_XY_CFG0, val);
        if (error)
                return error;

        if (prop.max_x > max_x_hw) {
                dev_err(&client->dev, "Invalid maximum x-coordinate: %u > %u\n",
                        prop.max_x, max_x_hw);
                return -EINVAL;
        } else if (prop.max_x == 0) {
                error = iqs5xx_read_word(client, IQS5XX_X_RES, &max_x);
                if (error)
                        return error;

                input_abs_set_max(iqs5xx->input,
                                  prop.swap_x_y ? ABS_MT_POSITION_Y :
                                                  ABS_MT_POSITION_X,
                                  max_x);
        } else {
                max_x = (u16)prop.max_x;
        }

        if (prop.max_y > max_y_hw) {
                dev_err(&client->dev, "Invalid maximum y-coordinate: %u > %u\n",
                        prop.max_y, max_y_hw);
                return -EINVAL;
        } else if (prop.max_y == 0) {
                error = iqs5xx_read_word(client, IQS5XX_Y_RES, &max_y);
                if (error)
                        return error;

                input_abs_set_max(iqs5xx->input,
                                  prop.swap_x_y ? ABS_MT_POSITION_X :
                                                  ABS_MT_POSITION_Y,
                                  max_y);
        } else {
                max_y = (u16)prop.max_y;
        }

        /*
         * Write horizontal and vertical resolution to the device in case its
         * original defaults were overridden or swapped as per the properties
         * specified in the device tree.
         */
        error = iqs5xx_write_word(client,
                                  prop.swap_x_y ? IQS5XX_Y_RES : IQS5XX_X_RES,
                                  max_x);
        if (error)
                return error;

        error = iqs5xx_write_word(client,
                                  prop.swap_x_y ? IQS5XX_X_RES : IQS5XX_Y_RES,
                                  max_y);
        if (error)
                return error;

        error = input_mt_init_slots(iqs5xx->input, IQS5XX_NUM_CONTACTS,
                                    INPUT_MT_DIRECT);
        if (error)
                dev_err(&client->dev, "Failed to initialize slots: %d\n",
                        error);

        return error;
}

static int iqs5xx_dev_init(struct i2c_client *client)
{
        struct iqs5xx_private *iqs5xx = i2c_get_clientdata(client);
        struct iqs5xx_dev_id_info *dev_id_info;
        int error;
        u8 val;
        u8 buf[sizeof(*dev_id_info) + 1];

        error = iqs5xx_read_burst(client, IQS5XX_PROD_NUM,
                                  &buf[1], sizeof(*dev_id_info));
        if (error)
                return iqs5xx_bl_open(client);

        /*
         * A000 and B000 devices use 8-bit and 16-bit addressing, respectively.
         * Querying an A000 device's version information with 16-bit addressing
         * gives the appearance that the data is shifted by one byte; a nonzero
         * leading array element suggests this could be the case (in which case
         * the missing zero is prepended).
         */
        buf[0] = 0;
        dev_id_info = (struct iqs5xx_dev_id_info *)&buf[(buf[1] > 0) ? 0 : 1];

        switch (be16_to_cpu(dev_id_info->prod_num)) {
        case IQS5XX_PROD_NUM_IQS550:
        case IQS5XX_PROD_NUM_IQS572:
        case IQS5XX_PROD_NUM_IQS525:
                break;
        default:
                dev_err(&client->dev, "Unrecognized product number: %u\n",
                        be16_to_cpu(dev_id_info->prod_num));
                return -EINVAL;
        }

        switch (be16_to_cpu(dev_id_info->proj_num)) {
        case IQS5XX_PROJ_NUM_A000:
                dev_err(&client->dev, "Unsupported project number: %u\n",
                        be16_to_cpu(dev_id_info->proj_num));
                return iqs5xx_bl_open(client);
        case IQS5XX_PROJ_NUM_B000:
                break;
        default:
                dev_err(&client->dev, "Unrecognized project number: %u\n",
                        be16_to_cpu(dev_id_info->proj_num));
                return -EINVAL;
        }

        if (dev_id_info->major_ver < IQS5XX_MAJOR_VER_MIN) {
                dev_err(&client->dev, "Unsupported major version: %u\n",
                        dev_id_info->major_ver);
                return iqs5xx_bl_open(client);
        }

        switch (dev_id_info->bl_status) {
        case IQS5XX_BL_STATUS_AVAIL:
        case IQS5XX_BL_STATUS_NONE:
                break;
        default:
                dev_err(&client->dev,
                        "Unrecognized bootloader status: 0x%02X\n",
                        dev_id_info->bl_status);
                return -EINVAL;
        }

        error = iqs5xx_axis_init(client);
        if (error)
                return error;

        error = iqs5xx_read_byte(client, IQS5XX_SYS_CFG0, &val);
        if (error)
                return error;

        val |= IQS5XX_SETUP_COMPLETE;
        val &= ~IQS5XX_SW_INPUT_EVENT;
        error = iqs5xx_write_byte(client, IQS5XX_SYS_CFG0, val);
        if (error)
                return error;

        val = IQS5XX_TP_EVENT | IQS5XX_EVENT_MODE;
        error = iqs5xx_write_byte(client, IQS5XX_SYS_CFG1, val);
        if (error)
                return error;

        error = iqs5xx_write_byte(client, IQS5XX_END_COMM, 0);
        if (error)
                return error;

        iqs5xx->bl_status = dev_id_info->bl_status;

        /*
         * Closure of the first communication window that appears following the
         * release of reset appears to kick off an initialization period during
         * which further communication is met with clock stretching. The return
         * from this function is delayed so that further communication attempts
         * avoid this period.
         */
        msleep(100);

        return 0;
}

static irqreturn_t iqs5xx_irq(int irq, void *data)
{
        struct iqs5xx_private *iqs5xx = data;
        struct iqs5xx_touch_data touch_data[IQS5XX_NUM_CONTACTS];
        struct i2c_client *client = iqs5xx->client;
        struct input_dev *input = iqs5xx->input;
        int error, i;

        /*
         * This check is purely a precaution, as the device does not assert the
         * RDY output during bootloader mode. If the device operates outside of
         * bootloader mode, the input device is guaranteed to be allocated.
         */
        if (iqs5xx->bl_status == IQS5XX_BL_STATUS_RESET)
                return IRQ_NONE;

        error = iqs5xx_read_burst(client, IQS5XX_ABS_X,
                                  touch_data, sizeof(touch_data));
        if (error)
                return IRQ_NONE;

        for (i = 0; i < ARRAY_SIZE(touch_data); i++) {
                u16 pressure = be16_to_cpu(touch_data[i].strength);

                input_mt_slot(input, i);
                if (input_mt_report_slot_state(input, MT_TOOL_FINGER,
                                               pressure != 0)) {
                        input_report_abs(input, ABS_MT_POSITION_X,
                                         be16_to_cpu(touch_data[i].abs_x));
                        input_report_abs(input, ABS_MT_POSITION_Y,
                                         be16_to_cpu(touch_data[i].abs_y));
                        input_report_abs(input, ABS_MT_PRESSURE, pressure);
                }
        }

        input_mt_sync_frame(input);
        input_sync(input);

        error = iqs5xx_write_byte(client, IQS5XX_END_COMM, 0);
        if (error)
                return IRQ_NONE;

        /*
         * Once the communication window is closed, a small delay is added to
         * ensure the device's RDY output has been deasserted by the time the
         * interrupt handler returns.
         */
        usleep_range(50, 100);

        return IRQ_HANDLED;
}

static int iqs5xx_fw_file_parse(struct i2c_client *client,
                                const char *fw_file, u8 *pmap)
{
        const struct firmware *fw;
        struct iqs5xx_ihex_rec *rec;
        size_t pos = 0;
        int error, i;
        u16 rec_num = 1;
        u16 rec_addr;
        u8 rec_len, rec_type, rec_chksm, chksm;
        u8 rec_hdr[IQS5XX_REC_HDR_LEN];
        u8 rec_data[IQS5XX_REC_LEN_MAX];

        /*
         * Firmware exported from the vendor's configuration tool deviates from
         * standard ihex as follows: (1) the checksum for records corresponding
         * to user-exported settings is not recalculated, and (2) an address of
         * 0xFFFF is used for the EOF record.
         *
         * Because the ihex2fw tool tolerates neither (1) nor (2), the slightly
         * nonstandard ihex firmware is parsed directly by the driver.
         */
        error = request_firmware(&fw, fw_file, &client->dev);
        if (error) {
                dev_err(&client->dev, "Failed to request firmware %s: %d\n",
                        fw_file, error);
                return error;
        }

        do {
                if (pos + sizeof(*rec) > fw->size) {
                        dev_err(&client->dev, "Insufficient firmware size\n");
                        error = -EINVAL;
                        break;
                }
                rec = (struct iqs5xx_ihex_rec *)(fw->data + pos);
                pos += sizeof(*rec);

                if (rec->start != ':') {
                        dev_err(&client->dev, "Invalid start at record %u\n",
                                rec_num);
                        error = -EINVAL;
                        break;
                }

                error = hex2bin(rec_hdr, rec->len, sizeof(rec_hdr));
                if (error) {
                        dev_err(&client->dev, "Invalid header at record %u\n",
                                rec_num);
                        break;
                }

                rec_len = *rec_hdr;
                rec_addr = get_unaligned_be16(rec_hdr + sizeof(rec_len));
                rec_type = *(rec_hdr + sizeof(rec_len) + sizeof(rec_addr));

                if (pos + rec_len * 2 > fw->size) {
                        dev_err(&client->dev, "Insufficient firmware size\n");
                        error = -EINVAL;
                        break;
                }
                pos += (rec_len * 2);

                error = hex2bin(rec_data, rec->data, rec_len);
                if (error) {
                        dev_err(&client->dev, "Invalid data at record %u\n",
                                rec_num);
                        break;
                }

                error = hex2bin(&rec_chksm,
                                rec->data + rec_len * 2, sizeof(rec_chksm));
                if (error) {
                        dev_err(&client->dev, "Invalid checksum at record %u\n",
                                rec_num);
                        break;
                }

                chksm = 0;
                for (i = 0; i < sizeof(rec_hdr); i++)
                        chksm += rec_hdr[i];
                for (i = 0; i < rec_len; i++)
                        chksm += rec_data[i];
                chksm = ~chksm + 1;

                if (chksm != rec_chksm && rec_addr < IQS5XX_CSTM) {
                        dev_err(&client->dev,
                                "Incorrect checksum at record %u\n",
                                rec_num);
                        error = -EINVAL;
                        break;
                }

                switch (rec_type) {
                case IQS5XX_REC_TYPE_DATA:
                        if (rec_addr < IQS5XX_CHKSM ||
                            rec_addr > IQS5XX_PMAP_END) {
                                dev_err(&client->dev,
                                        "Invalid address at record %u\n",
                                        rec_num);
                                error = -EINVAL;
                        } else {
                                memcpy(pmap + rec_addr - IQS5XX_CHKSM,
                                       rec_data, rec_len);
                        }
                        break;
                case IQS5XX_REC_TYPE_EOF:
                        break;
                default:
                        dev_err(&client->dev, "Invalid type at record %u\n",
                                rec_num);
                        error = -EINVAL;
                }

                if (error)
                        break;

                rec_num++;
                while (pos < fw->size) {
                        if (*(fw->data + pos) == ':')
                                break;
                        pos++;
                }
        } while (rec_type != IQS5XX_REC_TYPE_EOF);

        release_firmware(fw);

        return error;
}

static int iqs5xx_fw_file_write(struct i2c_client *client, const char *fw_file)
{
        struct iqs5xx_private *iqs5xx = i2c_get_clientdata(client);
        int error;
        u8 *pmap;

        if (iqs5xx->bl_status == IQS5XX_BL_STATUS_NONE)
                return -EPERM;

        pmap = kzalloc(IQS5XX_PMAP_LEN, GFP_KERNEL);
        if (!pmap)
                return -ENOMEM;

        error = iqs5xx_fw_file_parse(client, fw_file, pmap);
        if (error)
                goto err_kfree;

        mutex_lock(&iqs5xx->lock);

        /*
         * Disable the interrupt line in case the first attempt(s) to enter the
         * bootloader don't happen quickly enough, in which case the device may
         * assert the RDY output until the next attempt.
         */
        disable_irq(client->irq);

        iqs5xx->bl_status = IQS5XX_BL_STATUS_RESET;

        error = iqs5xx_bl_cmd(client, IQS5XX_BL_CMD_VER, 0);
        if (error) {
                error = iqs5xx_bl_open(client);
                if (error)
                        goto err_reset;
        }

        error = iqs5xx_bl_write(client, IQS5XX_CHKSM, pmap, IQS5XX_PMAP_LEN);
        if (error)
                goto err_reset;

        error = iqs5xx_bl_cmd(client, IQS5XX_BL_CMD_CRC, 0);
        if (error)
                goto err_reset;

        error = iqs5xx_bl_verify(client, IQS5XX_CSTM,
                                 pmap + IQS5XX_CHKSM_LEN + IQS5XX_APP_LEN,
                                 IQS5XX_CSTM_LEN);
        if (error)
                goto err_reset;

        error = iqs5xx_bl_cmd(client, IQS5XX_BL_CMD_EXEC, 0);

err_reset:
        if (error) {
                iqs5xx_reset(client);
                usleep_range(10000, 10100);
        }

        error = iqs5xx_dev_init(client);
        if (!error && iqs5xx->bl_status == IQS5XX_BL_STATUS_RESET)
                error = -EINVAL;

        enable_irq(client->irq);

        mutex_unlock(&iqs5xx->lock);

err_kfree:
        kfree(pmap);

        return error;
}

static ssize_t fw_file_store(struct device *dev, struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct iqs5xx_private *iqs5xx = dev_get_drvdata(dev);
        struct i2c_client *client = iqs5xx->client;
        size_t len = count;
        bool input_reg = !iqs5xx->input;
        char fw_file[IQS5XX_FW_FILE_LEN + 1];
        int error;

        if (!len)
                return -EINVAL;

        if (buf[len - 1] == '\n')
                len--;

        if (len > IQS5XX_FW_FILE_LEN)
                return -ENAMETOOLONG;

        memcpy(fw_file, buf, len);
        fw_file[len] = '\0';

        error = iqs5xx_fw_file_write(client, fw_file);
        if (error)
                return error;

        /*
         * If the input device was not allocated already, it is guaranteed to
         * be allocated by this point and can finally be registered.
         */
        if (input_reg) {
                error = input_register_device(iqs5xx->input);
                if (error) {
                        dev_err(&client->dev,
                                "Failed to register device: %d\n",
                                error);
                        return error;
                }
        }

        return count;
}

static DEVICE_ATTR_WO(fw_file);

static struct attribute *iqs5xx_attrs[] = {

        &dev_attr_fw_file.attr,
        NULL,
};

static const struct attribute_group iqs5xx_attr_group = {
        .attrs = iqs5xx_attrs,
};

static int __maybe_unused iqs5xx_suspend(struct device *dev)
{
        struct iqs5xx_private *iqs5xx = dev_get_drvdata(dev);
        struct input_dev *input = iqs5xx->input;
        int error = 0;

        if (!input)
                return error;

        mutex_lock(&input->mutex);

        if (input->users)
                error = iqs5xx_set_state(iqs5xx->client, IQS5XX_SUSPEND);

        mutex_unlock(&input->mutex);

        return error;
}

static int __maybe_unused iqs5xx_resume(struct device *dev)
{
        struct iqs5xx_private *iqs5xx = dev_get_drvdata(dev);
        struct input_dev *input = iqs5xx->input;
        int error = 0;

        if (!input)
                return error;

        mutex_lock(&input->mutex);

        if (input->users)
                error = iqs5xx_set_state(iqs5xx->client, IQS5XX_RESUME);

        mutex_unlock(&input->mutex);

        return error;
}

static SIMPLE_DEV_PM_OPS(iqs5xx_pm, iqs5xx_suspend, iqs5xx_resume);

static int iqs5xx_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct iqs5xx_private *iqs5xx;
        int error;

        iqs5xx = devm_kzalloc(&client->dev, sizeof(*iqs5xx), GFP_KERNEL);
        if (!iqs5xx)
                return -ENOMEM;

        i2c_set_clientdata(client, iqs5xx);
        iqs5xx->client = client;

        iqs5xx->reset_gpio = devm_gpiod_get(&client->dev,
                                            "reset", GPIOD_OUT_LOW);
        if (IS_ERR(iqs5xx->reset_gpio)) {
                error = PTR_ERR(iqs5xx->reset_gpio);
                dev_err(&client->dev, "Failed to request GPIO: %d\n", error);
                return error;
        }

        mutex_init(&iqs5xx->lock);

        iqs5xx_reset(client);
        usleep_range(10000, 10100);

        error = iqs5xx_dev_init(client);
        if (error)
                return error;

        error = devm_request_threaded_irq(&client->dev, client->irq,
                                          NULL, iqs5xx_irq, IRQF_ONESHOT,
                                          client->name, iqs5xx);
        if (error) {
                dev_err(&client->dev, "Failed to request IRQ: %d\n", error);
                return error;
        }

        error = devm_device_add_group(&client->dev, &iqs5xx_attr_group);
        if (error) {
                dev_err(&client->dev, "Failed to add attributes: %d\n", error);
                return error;
        }

        if (iqs5xx->input) {
                error = input_register_device(iqs5xx->input);
                if (error)
                        dev_err(&client->dev,
                                "Failed to register device: %d\n",
                                error);
        }

        return error;
}

static const struct i2c_device_id iqs5xx_id[] = {
        { "iqs550", 0 },
        { "iqs572", 1 },
        { "iqs525", 2 },
        { }
};
MODULE_DEVICE_TABLE(i2c, iqs5xx_id);

static const struct of_device_id iqs5xx_of_match[] = {
        { .compatible = "azoteq,iqs550" },
        { .compatible = "azoteq,iqs572" },
        { .compatible = "azoteq,iqs525" },
        { }
};
MODULE_DEVICE_TABLE(of, iqs5xx_of_match);

static struct i2c_driver iqs5xx_i2c_driver = {
        .driver = {
                .name           = "iqs5xx",
                .of_match_table = iqs5xx_of_match,
                .pm             = &iqs5xx_pm,
        },
        .id_table       = iqs5xx_id,
        .probe          = iqs5xx_probe,
};
module_i2c_driver(iqs5xx_i2c_driver);

MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
MODULE_DESCRIPTION("Azoteq IQS550/572/525 Trackpad/Touchscreen Controller");
MODULE_LICENSE("GPL");