/*
 * Allwinner sunxi resistive touchscreen controller driver
 *
 * Copyright (C) 2013 - 2014 Hans de Goede <hdegoede@redhat.com>
 *
 * The hwmon parts are based on work by Corentin LABBE which is:
 * Copyright (C) 2013 Corentin LABBE <clabbe.montjoie@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 */

/*
 * The sun4i-ts controller is capable of detecting a second touch, but when a
 * second touch is present then the accuracy becomes so bad the reported touch
 * location is not useable.
 *
 * The original android driver contains some complicated heuristics using the
 * aprox. distance between the 2 touches to see if the user is making a pinch
 * open / close movement, and then reports emulated multi-touch events around
 * the last touch coordinate (as the dual-touch coordinates are worthless).
 *
 * These kinds of heuristics are just asking for trouble (and don't belong
 * in the kernel). So this driver offers straight forward, reliable single
 * touch functionality only.
 *
 * s.a. A20 User Manual "1.15 TP" (Documentation/arm/sunxi/README)
 * (looks like the description in the A20 User Manual v1.3 is better
 * than the one in the A10 User Manual v.1.5)
 */

#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/thermal.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define TP_CTRL0                0x00
#define TP_CTRL1                0x04
#define TP_CTRL2                0x08
#define TP_CTRL3                0x0c
#define TP_INT_FIFOC            0x10
#define TP_INT_FIFOS            0x14
#define TP_TPR                  0x18
#define TP_CDAT                 0x1c
#define TEMP_DATA               0x20
#define TP_DATA                 0x24

/* TP_CTRL0 bits */
#define ADC_FIRST_DLY(x)        ((x) << 24) /* 8 bits */
#define ADC_FIRST_DLY_MODE(x)   ((x) << 23)
#define ADC_CLK_SEL(x)          ((x) << 22)
#define ADC_CLK_DIV(x)          ((x) << 20) /* 3 bits */
#define FS_DIV(x)               ((x) << 16) /* 4 bits */
#define T_ACQ(x)                ((x) << 0) /* 16 bits */

/* TP_CTRL1 bits */
#define STYLUS_UP_DEBOUN(x)     ((x) << 12) /* 8 bits */
#define STYLUS_UP_DEBOUN_EN(x)  ((x) << 9)
#define TOUCH_PAN_CALI_EN(x)    ((x) << 6)
#define TP_DUAL_EN(x)           ((x) << 5)
#define TP_MODE_EN(x)           ((x) << 4)
#define TP_ADC_SELECT(x)        ((x) << 3)
#define ADC_CHAN_SELECT(x)      ((x) << 0)  /* 3 bits */

/* on sun6i, bits 3~6 are left shifted by 1 to 4~7 */
#define SUN6I_TP_MODE_EN(x)     ((x) << 5)

/* TP_CTRL2 bits */
#define TP_SENSITIVE_ADJUST(x)  ((x) << 28) /* 4 bits */
#define TP_MODE_SELECT(x)       ((x) << 26) /* 2 bits */
#define PRE_MEA_EN(x)           ((x) << 24)
#define PRE_MEA_THRE_CNT(x)     ((x) << 0) /* 24 bits */

/* TP_CTRL3 bits */
#define FILTER_EN(x)            ((x) << 2)
#define FILTER_TYPE(x)          ((x) << 0)  /* 2 bits */

/* TP_INT_FIFOC irq and fifo mask / control bits */
#define TEMP_IRQ_EN(x)          ((x) << 18)
#define OVERRUN_IRQ_EN(x)       ((x) << 17)
#define DATA_IRQ_EN(x)          ((x) << 16)
#define TP_DATA_XY_CHANGE(x)    ((x) << 13)
#define FIFO_TRIG(x)            ((x) << 8)  /* 5 bits */
#define DATA_DRQ_EN(x)          ((x) << 7)
#define FIFO_FLUSH(x)           ((x) << 4)
#define TP_UP_IRQ_EN(x)         ((x) << 1)
#define TP_DOWN_IRQ_EN(x)       ((x) << 0)

/* TP_INT_FIFOS irq and fifo status bits */
#define TEMP_DATA_PENDING       BIT(18)
#define FIFO_OVERRUN_PENDING    BIT(17)
#define FIFO_DATA_PENDING       BIT(16)
#define TP_IDLE_FLG             BIT(2)
#define TP_UP_PENDING           BIT(1)
#define TP_DOWN_PENDING         BIT(0)

/* TP_TPR bits */
#define TEMP_ENABLE(x)          ((x) << 16)
#define TEMP_PERIOD(x)          ((x) << 0)  /* t = x * 256 * 16 / clkin */

struct sun4i_ts_data {
        struct device *dev;
        struct input_dev *input;
        void __iomem *base;
        unsigned int irq;
        bool ignore_fifo_data;
        int temp_data;
        int temp_offset;
        int temp_step;
};

static void sun4i_ts_irq_handle_input(struct sun4i_ts_data *ts, u32 reg_val)
{
        u32 x, y;

        if (reg_val & FIFO_DATA_PENDING) {
                x = readl(ts->base + TP_DATA);
                y = readl(ts->base + TP_DATA);
                /* The 1st location reported after an up event is unreliable */
                if (!ts->ignore_fifo_data) {
                        input_report_abs(ts->input, ABS_X, x);
                        input_report_abs(ts->input, ABS_Y, y);
                        /*
                         * The hardware has a separate down status bit, but
                         * that gets set before we get the first location,
                         * resulting in reporting a click on the old location.
                         */
                        input_report_key(ts->input, BTN_TOUCH, 1);
                        input_sync(ts->input);
                } else {
                        ts->ignore_fifo_data = false;
                }
        }

        if (reg_val & TP_UP_PENDING) {
                ts->ignore_fifo_data = true;
                input_report_key(ts->input, BTN_TOUCH, 0);
                input_sync(ts->input);
        }
}

static irqreturn_t sun4i_ts_irq(int irq, void *dev_id)
{
        struct sun4i_ts_data *ts = dev_id;
        u32 reg_val;

        reg_val  = readl(ts->base + TP_INT_FIFOS);

        if (reg_val & TEMP_DATA_PENDING)
                ts->temp_data = readl(ts->base + TEMP_DATA);

        if (ts->input)
                sun4i_ts_irq_handle_input(ts, reg_val);

        writel(reg_val, ts->base + TP_INT_FIFOS);

        return IRQ_HANDLED;
}

static int sun4i_ts_open(struct input_dev *dev)
{
        struct sun4i_ts_data *ts = input_get_drvdata(dev);

        /* Flush, set trig level to 1, enable temp, data and up irqs */
        writel(TEMP_IRQ_EN(1) | DATA_IRQ_EN(1) | FIFO_TRIG(1) | FIFO_FLUSH(1) |
                TP_UP_IRQ_EN(1), ts->base + TP_INT_FIFOC);

        return 0;
}

static void sun4i_ts_close(struct input_dev *dev)
{
        struct sun4i_ts_data *ts = input_get_drvdata(dev);

        /* Deactivate all input IRQs */
        writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
}

static int sun4i_get_temp(const struct sun4i_ts_data *ts, int *temp)
{
        /* No temp_data until the first irq */
        if (ts->temp_data == -1)
                return -EAGAIN;

        *temp = ts->temp_data * ts->temp_step - ts->temp_offset;

        return 0;
}

static int sun4i_get_tz_temp(void *data, int *temp)
{
        return sun4i_get_temp(data, temp);
}

static const struct thermal_zone_of_device_ops sun4i_ts_tz_ops = {
        .get_temp = sun4i_get_tz_temp,
};

static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
                         char *buf)
{
        struct sun4i_ts_data *ts = dev_get_drvdata(dev);
        int temp;
        int error;

        error = sun4i_get_temp(ts, &temp);
        if (error)
                return error;

        return sprintf(buf, "%d\n", temp);
}

static ssize_t show_temp_label(struct device *dev,
                              struct device_attribute *devattr, char *buf)
{
        return sprintf(buf, "SoC temperature\n");
}

static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL);
static DEVICE_ATTR(temp1_label, S_IRUGO, show_temp_label, NULL);

static struct attribute *sun4i_ts_attrs[] = {
        &dev_attr_temp1_input.attr,
        &dev_attr_temp1_label.attr,
        NULL
};
ATTRIBUTE_GROUPS(sun4i_ts);

static int sun4i_ts_probe(struct platform_device *pdev)
{
        struct sun4i_ts_data *ts;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct device *hwmon;
        int error;
        u32 reg;
        bool ts_attached;
        u32 tp_sensitive_adjust = 15;
        u32 filter_type = 1;

        ts = devm_kzalloc(dev, sizeof(struct sun4i_ts_data), GFP_KERNEL);
        if (!ts)
                return -ENOMEM;

        ts->dev = dev;
        ts->ignore_fifo_data = true;
        ts->temp_data = -1;
        if (of_device_is_compatible(np, "allwinner,sun6i-a31-ts")) {
                /* Allwinner SDK has temperature (C) = (value / 6) - 271 */
                ts->temp_offset = 271000;
                ts->temp_step = 167;
        } else if (of_device_is_compatible(np, "allwinner,sun4i-a10-ts")) {
                /*
                 * The A10 temperature sensor has quite a wide spread, these
                 * parameters are based on the averaging of the calibration
                 * results of 4 completely different boards, with a spread of
                 * temp_step from 0.096 - 0.170 and temp_offset from 176 - 331.
                 */
                ts->temp_offset = 257000;
                ts->temp_step = 133;
        } else {
                /*
                 * The user manuals do not contain the formula for calculating
                 * the temperature. The formula used here is from the AXP209,
                 * which is designed by X-Powers, an affiliate of Allwinner:
                 *
                 *     temperature (C) = (value * 0.1) - 144.7
                 *
                 * Allwinner does not have any documentation whatsoever for
                 * this hardware. Moreover, it is claimed that the sensor
                 * is inaccurate and cannot work properly.
                 */
                ts->temp_offset = 144700;
                ts->temp_step = 100;
        }

        ts_attached = of_property_read_bool(np, "allwinner,ts-attached");
        if (ts_attached) {
                ts->input = devm_input_allocate_device(dev);
                if (!ts->input)
                        return -ENOMEM;

                ts->input->name = pdev->name;
                ts->input->phys = "sun4i_ts/input0";
                ts->input->open = sun4i_ts_open;
                ts->input->close = sun4i_ts_close;
                ts->input->id.bustype = BUS_HOST;
                ts->input->id.vendor = 0x0001;
                ts->input->id.product = 0x0001;
                ts->input->id.version = 0x0100;
                ts->input->evbit[0] =  BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);
                __set_bit(BTN_TOUCH, ts->input->keybit);
                input_set_abs_params(ts->input, ABS_X, 0, 4095, 0, 0);
                input_set_abs_params(ts->input, ABS_Y, 0, 4095, 0, 0);
                input_set_drvdata(ts->input, ts);
        }

        ts->base = devm_ioremap_resource(dev,
                              platform_get_resource(pdev, IORESOURCE_MEM, 0));
        if (IS_ERR(ts->base))
                return PTR_ERR(ts->base);

        ts->irq = platform_get_irq(pdev, 0);
        error = devm_request_irq(dev, ts->irq, sun4i_ts_irq, 0, "sun4i-ts", ts);
        if (error)
                return error;

        /*
         * Select HOSC clk, clkin = clk / 6, adc samplefreq = clkin / 8192,
         * t_acq = clkin / (16 * 64)
         */
        writel(ADC_CLK_SEL(0) | ADC_CLK_DIV(2) | FS_DIV(7) | T_ACQ(63),
               ts->base + TP_CTRL0);

        /*
         * tp_sensitive_adjust is an optional property
         * tp_mode = 0 : only x and y coordinates, as we don't use dual touch
         */
        of_property_read_u32(np, "allwinner,tp-sensitive-adjust",
                             &tp_sensitive_adjust);
        writel(TP_SENSITIVE_ADJUST(tp_sensitive_adjust) | TP_MODE_SELECT(0),
               ts->base + TP_CTRL2);

        /*
         * Enable median and averaging filter, optional property for
         * filter type.
         */
        of_property_read_u32(np, "allwinner,filter-type", &filter_type);
        writel(FILTER_EN(1) | FILTER_TYPE(filter_type), ts->base + TP_CTRL3);

        /* Enable temperature measurement, period 1953 (2 seconds) */
        writel(TEMP_ENABLE(1) | TEMP_PERIOD(1953), ts->base + TP_TPR);

        /*
         * Set stylus up debounce to aprox 10 ms, enable debounce, and
         * finally enable tp mode.
         */
        reg = STYLUS_UP_DEBOUN(5) | STYLUS_UP_DEBOUN_EN(1);
        if (of_device_is_compatible(np, "allwinner,sun6i-a31-ts"))
                reg |= SUN6I_TP_MODE_EN(1);
        else
                reg |= TP_MODE_EN(1);
        writel(reg, ts->base + TP_CTRL1);

        /*
         * The thermal core does not register hwmon devices for DT-based
         * thermal zone sensors, such as this one.
         */
        hwmon = devm_hwmon_device_register_with_groups(ts->dev, "sun4i_ts",
                                                       ts, sun4i_ts_groups);
        if (IS_ERR(hwmon))
                return PTR_ERR(hwmon);

        devm_thermal_zone_of_sensor_register(ts->dev, 0, ts, &sun4i_ts_tz_ops);

        writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);

        if (ts_attached) {
                error = input_register_device(ts->input);
                if (error) {
                        writel(0, ts->base + TP_INT_FIFOC);
                        return error;
                }
        }

        platform_set_drvdata(pdev, ts);
        return 0;
}

static int sun4i_ts_remove(struct platform_device *pdev)
{
        struct sun4i_ts_data *ts = platform_get_drvdata(pdev);

        /* Explicit unregister to avoid open/close changing the imask later */
        if (ts->input)
                input_unregister_device(ts->input);

        /* Deactivate all IRQs */
        writel(0, ts->base + TP_INT_FIFOC);

        return 0;
}

static const struct of_device_id sun4i_ts_of_match[] = {
        { .compatible = "allwinner,sun4i-a10-ts", },
        { .compatible = "allwinner,sun5i-a13-ts", },
        { .compatible = "allwinner,sun6i-a31-ts", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sun4i_ts_of_match);

static struct platform_driver sun4i_ts_driver = {
        .driver = {
                .name   = "sun4i-ts",
                .of_match_table = of_match_ptr(sun4i_ts_of_match),
        },
        .probe  = sun4i_ts_probe,
        .remove = sun4i_ts_remove,
};

module_platform_driver(sun4i_ts_driver);

MODULE_DESCRIPTION("Allwinner sun4i resistive touchscreen controller driver");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");