/*
 * TI Touch Screen driver
 *
 * Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */


#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/sort.h>
#include <linux/pm_wakeirq.h>

#include <linux/mfd/ti_am335x_tscadc.h>

#define ADCFSM_STEPID           0x10
#define SEQ_SETTLE              275
#define MAX_12BIT               ((1 << 12) - 1)

#define TSC_IRQENB_MASK         (IRQENB_FIFO0THRES | IRQENB_EOS | IRQENB_HW_PEN)

static const int config_pins[] = {
        STEPCONFIG_XPP,
        STEPCONFIG_XNN,
        STEPCONFIG_YPP,
        STEPCONFIG_YNN,
};

struct titsc {
        struct input_dev        *input;
        struct ti_tscadc_dev    *mfd_tscadc;
        struct device           *dev;
        unsigned int            irq;
        unsigned int            wires;
        unsigned int            x_plate_resistance;
        bool                    pen_down;
        int                     coordinate_readouts;
        u32                     config_inp[4];
        u32                     bit_xp, bit_xn, bit_yp, bit_yn;
        u32                     inp_xp, inp_xn, inp_yp, inp_yn;
        u32                     step_mask;
        u32                     charge_delay;
};

static unsigned int titsc_readl(struct titsc *ts, unsigned int reg)
{
        return readl(ts->mfd_tscadc->tscadc_base + reg);
}

static void titsc_writel(struct titsc *tsc, unsigned int reg,
                                        unsigned int val)
{
        writel(val, tsc->mfd_tscadc->tscadc_base + reg);
}

static int titsc_config_wires(struct titsc *ts_dev)
{
        u32 analog_line[4];
        u32 wire_order[4];
        int i, bit_cfg;

        for (i = 0; i < 4; i++) {
                /*
                 * Get the order in which TSC wires are attached
                 * w.r.t. each of the analog input lines on the EVM.
                 */
                analog_line[i] = (ts_dev->config_inp[i] & 0xF0) >> 4;
                wire_order[i] = ts_dev->config_inp[i] & 0x0F;
                if (WARN_ON(analog_line[i] > 7))
                        return -EINVAL;
                if (WARN_ON(wire_order[i] >= ARRAY_SIZE(config_pins)))
                        return -EINVAL;
        }

        for (i = 0; i < 4; i++) {
                int an_line;
                int wi_order;

                an_line = analog_line[i];
                wi_order = wire_order[i];
                bit_cfg = config_pins[wi_order];
                if (bit_cfg == 0)
                        return -EINVAL;
                switch (wi_order) {
                case 0:
                        ts_dev->bit_xp = bit_cfg;
                        ts_dev->inp_xp = an_line;
                        break;

                case 1:
                        ts_dev->bit_xn = bit_cfg;
                        ts_dev->inp_xn = an_line;
                        break;

                case 2:
                        ts_dev->bit_yp = bit_cfg;
                        ts_dev->inp_yp = an_line;
                        break;
                case 3:
                        ts_dev->bit_yn = bit_cfg;
                        ts_dev->inp_yn = an_line;
                        break;
                }
        }
        return 0;
}

static void titsc_step_config(struct titsc *ts_dev)
{
        unsigned int    config;
        int i, n;
        int end_step, first_step, tsc_steps;
        u32 stepenable;

        config = STEPCONFIG_MODE_HWSYNC |
                        STEPCONFIG_AVG_16 | ts_dev->bit_xp |
                        STEPCONFIG_INM_ADCREFM;
        switch (ts_dev->wires) {
        case 4:
                config |= STEPCONFIG_INP(ts_dev->inp_yp) | ts_dev->bit_xn;
                break;
        case 5:
                config |= ts_dev->bit_yn |
                                STEPCONFIG_INP_AN4 | ts_dev->bit_xn |
                                ts_dev->bit_yp;
                break;
        case 8:
                config |= STEPCONFIG_INP(ts_dev->inp_yp) | ts_dev->bit_xn;
                break;
        }

        tsc_steps = ts_dev->coordinate_readouts * 2 + 2;
        first_step = TOTAL_STEPS - tsc_steps;
        /* Steps 16 to 16-coordinate_readouts is for X */
        end_step = first_step + tsc_steps;
        n = 0;
        for (i = end_step - ts_dev->coordinate_readouts; i < end_step; i++) {
                titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
                titsc_writel(ts_dev, REG_STEPDELAY(i),
                             n++ == 0 ? STEPCONFIG_OPENDLY : 0);
        }

        config = STEPCONFIG_MODE_HWSYNC |
                        STEPCONFIG_AVG_16 | ts_dev->bit_yn |
                        STEPCONFIG_INM_ADCREFM;
        switch (ts_dev->wires) {
        case 4:
                config |= ts_dev->bit_yp | STEPCONFIG_INP(ts_dev->inp_xp);
                break;
        case 5:
                config |= ts_dev->bit_xp | STEPCONFIG_INP_AN4 |
                                STEPCONFIG_XNP | STEPCONFIG_YPN;
                break;
        case 8:
                config |= ts_dev->bit_yp | STEPCONFIG_INP(ts_dev->inp_xp);
                break;
        }

        /* 1 ... coordinate_readouts is for Y */
        end_step = first_step + ts_dev->coordinate_readouts;
        n = 0;
        for (i = first_step; i < end_step; i++) {
                titsc_writel(ts_dev, REG_STEPCONFIG(i), config);
                titsc_writel(ts_dev, REG_STEPDELAY(i),
                             n++ == 0 ? STEPCONFIG_OPENDLY : 0);
        }

        /* Make CHARGECONFIG same as IDLECONFIG */

        config = titsc_readl(ts_dev, REG_IDLECONFIG);
        titsc_writel(ts_dev, REG_CHARGECONFIG, config);
        titsc_writel(ts_dev, REG_CHARGEDELAY, ts_dev->charge_delay);

        /* coordinate_readouts + 1 ... coordinate_readouts + 2 is for Z */
        config = STEPCONFIG_MODE_HWSYNC |
                        STEPCONFIG_AVG_16 | ts_dev->bit_yp |
                        ts_dev->bit_xn | STEPCONFIG_INM_ADCREFM |
                        STEPCONFIG_INP(ts_dev->inp_xp);
        titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
        titsc_writel(ts_dev, REG_STEPDELAY(end_step),
                        STEPCONFIG_OPENDLY);

        end_step++;
        config = STEPCONFIG_MODE_HWSYNC |
                        STEPCONFIG_AVG_16 | ts_dev->bit_yp |
                        ts_dev->bit_xn | STEPCONFIG_INM_ADCREFM |
                        STEPCONFIG_INP(ts_dev->inp_yn);
        titsc_writel(ts_dev, REG_STEPCONFIG(end_step), config);
        titsc_writel(ts_dev, REG_STEPDELAY(end_step),
                        STEPCONFIG_OPENDLY);

        /* The steps end ... end - readouts * 2 + 2 and bit 0 for TS_Charge */
        stepenable = 1;
        for (i = 0; i < tsc_steps; i++)
                stepenable |= 1 << (first_step + i + 1);

        ts_dev->step_mask = stepenable;
        am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
}

static int titsc_cmp_coord(const void *a, const void *b)
{
        return *(int *)a - *(int *)b;
}

static void titsc_read_coordinates(struct titsc *ts_dev,
                u32 *x, u32 *y, u32 *z1, u32 *z2)
{
        unsigned int yvals[7], xvals[7];
        unsigned int i, xsum = 0, ysum = 0;
        unsigned int creads = ts_dev->coordinate_readouts;

        for (i = 0; i < creads; i++) {
                yvals[i] = titsc_readl(ts_dev, REG_FIFO0);
                yvals[i] &= 0xfff;
        }

        *z1 = titsc_readl(ts_dev, REG_FIFO0);
        *z1 &= 0xfff;
        *z2 = titsc_readl(ts_dev, REG_FIFO0);
        *z2 &= 0xfff;

        for (i = 0; i < creads; i++) {
                xvals[i] = titsc_readl(ts_dev, REG_FIFO0);
                xvals[i] &= 0xfff;
        }

        /*
         * If co-ordinates readouts is less than 4 then
         * report the average. In case of 4 or more
         * readouts, sort the co-ordinate samples, drop
         * min and max values and report the average of
         * remaining values.
         */
        if (creads <=  3) {
                for (i = 0; i < creads; i++) {
                        ysum += yvals[i];
                        xsum += xvals[i];
                }
                ysum /= creads;
                xsum /= creads;
        } else {
                sort(yvals, creads, sizeof(unsigned int),
                     titsc_cmp_coord, NULL);
                sort(xvals, creads, sizeof(unsigned int),
                     titsc_cmp_coord, NULL);
                for (i = 1; i < creads - 1; i++) {
                        ysum += yvals[i];
                        xsum += xvals[i];
                }
                ysum /= creads - 2;
                xsum /= creads - 2;
        }
        *y = ysum;
        *x = xsum;
}

static irqreturn_t titsc_irq(int irq, void *dev)
{
        struct titsc *ts_dev = dev;
        struct input_dev *input_dev = ts_dev->input;
        unsigned int fsm, status, irqclr = 0;
        unsigned int x = 0, y = 0;
        unsigned int z1, z2, z;

        status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
        if (status & IRQENB_HW_PEN) {
                ts_dev->pen_down = true;
                irqclr |= IRQENB_HW_PEN;
                pm_stay_awake(ts_dev->dev);
        }

        if (status & IRQENB_PENUP) {
                fsm = titsc_readl(ts_dev, REG_ADCFSM);
                if (fsm == ADCFSM_STEPID) {
                        ts_dev->pen_down = false;
                        input_report_key(input_dev, BTN_TOUCH, 0);
                        input_report_abs(input_dev, ABS_PRESSURE, 0);
                        input_sync(input_dev);
                        pm_relax(ts_dev->dev);
                } else {
                        ts_dev->pen_down = true;
                }
                irqclr |= IRQENB_PENUP;
        }

        if (status & IRQENB_EOS)
                irqclr |= IRQENB_EOS;

        /*
         * ADC and touchscreen share the IRQ line.
         * FIFO1 interrupts are used by ADC. Handle FIFO0 IRQs here only
         */
        if (status & IRQENB_FIFO0THRES) {

                titsc_read_coordinates(ts_dev, &x, &y, &z1, &z2);

                if (ts_dev->pen_down && z1 != 0 && z2 != 0) {
                        /*
                         * Calculate pressure using formula
                         * Resistance(touch) = x plate resistance *
                         * x position/4096 * ((z2 / z1) - 1)
                         */
                        z = z1 - z2;
                        z *= x;
                        z *= ts_dev->x_plate_resistance;
                        z /= z2;
                        z = (z + 2047) >> 12;

                        if (z <= MAX_12BIT) {
                                input_report_abs(input_dev, ABS_X, x);
                                input_report_abs(input_dev, ABS_Y, y);
                                input_report_abs(input_dev, ABS_PRESSURE, z);
                                input_report_key(input_dev, BTN_TOUCH, 1);
                                input_sync(input_dev);
                        }
                }
                irqclr |= IRQENB_FIFO0THRES;
        }
        if (irqclr) {
                titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);
                if (status & IRQENB_EOS)
                        am335x_tsc_se_set_cache(ts_dev->mfd_tscadc,
                                                ts_dev->step_mask);
                return IRQ_HANDLED;
        }
        return IRQ_NONE;
}

static int titsc_parse_dt(struct platform_device *pdev,
                                        struct titsc *ts_dev)
{
        struct device_node *node = pdev->dev.of_node;
        int err;

        if (!node)
                return -EINVAL;

        err = of_property_read_u32(node, "ti,wires", &ts_dev->wires);
        if (err < 0)
                return err;
        switch (ts_dev->wires) {
        case 4:
        case 5:
        case 8:
                break;
        default:
                return -EINVAL;
        }

        err = of_property_read_u32(node, "ti,x-plate-resistance",
                        &ts_dev->x_plate_resistance);
        if (err < 0)
                return err;

        /*
         * Try with the new binding first. If it fails, try again with
         * bogus, miss-spelled version.
         */
        err = of_property_read_u32(node, "ti,coordinate-readouts",
                        &ts_dev->coordinate_readouts);
        if (err < 0) {
                dev_warn(&pdev->dev, "please use 'ti,coordinate-readouts' instead\n");
                err = of_property_read_u32(node, "ti,coordiante-readouts",
                                &ts_dev->coordinate_readouts);
        }

        if (err < 0)
                return err;

        if (ts_dev->coordinate_readouts <= 0) {
                dev_warn(&pdev->dev,
                         "invalid co-ordinate readouts, resetting it to 5\n");
                ts_dev->coordinate_readouts = 5;
        } else if (ts_dev->coordinate_readouts > 6) {
                dev_warn(&pdev->dev,
                         "co-ordinate readouts too large, limiting to 6\n");
                ts_dev->coordinate_readouts = 6;
        }

        err = of_property_read_u32(node, "ti,charge-delay",
                                   &ts_dev->charge_delay);
        /*
         * If ti,charge-delay value is not specified, then use
         * CHARGEDLY_OPENDLY as the default value.
         */
        if (err < 0) {
                ts_dev->charge_delay = CHARGEDLY_OPENDLY;
                dev_warn(&pdev->dev, "ti,charge-delay not specified\n");
        }

        return of_property_read_u32_array(node, "ti,wire-config",
                        ts_dev->config_inp, ARRAY_SIZE(ts_dev->config_inp));
}

/*
 * The functions for inserting/removing driver as a module.
 */

static int titsc_probe(struct platform_device *pdev)
{
        struct titsc *ts_dev;
        struct input_dev *input_dev;
        struct ti_tscadc_dev *tscadc_dev = ti_tscadc_dev_get(pdev);
        int err;

        /* Allocate memory for device */
        ts_dev = kzalloc_obj(*ts_dev);
        input_dev = input_allocate_device();
        if (!ts_dev || !input_dev) {
                dev_err(&pdev->dev, "failed to allocate memory.\n");
                err = -ENOMEM;
                goto err_free_mem;
        }

        tscadc_dev->tsc = ts_dev;
        ts_dev->mfd_tscadc = tscadc_dev;
        ts_dev->input = input_dev;
        ts_dev->irq = tscadc_dev->irq;
        ts_dev->dev = &pdev->dev;

        err = titsc_parse_dt(pdev, ts_dev);
        if (err) {
                dev_err(&pdev->dev, "Could not find valid DT data.\n");
                goto err_free_mem;
        }

        err = request_irq(ts_dev->irq, titsc_irq,
                          IRQF_SHARED, pdev->dev.driver->name, ts_dev);
        if (err) {
                dev_err(&pdev->dev, "failed to allocate irq.\n");
                goto err_free_mem;
        }

        device_init_wakeup(&pdev->dev, true);
        err = dev_pm_set_wake_irq(&pdev->dev, ts_dev->irq);
        if (err)
                dev_err(&pdev->dev, "irq wake enable failed.\n");

        titsc_writel(ts_dev, REG_IRQSTATUS, TSC_IRQENB_MASK);
        titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_FIFO0THRES);
        titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_EOS);
        err = titsc_config_wires(ts_dev);
        if (err) {
                dev_err(&pdev->dev, "wrong i/p wire configuration\n");
                goto err_free_irq;
        }
        titsc_step_config(ts_dev);
        titsc_writel(ts_dev, REG_FIFO0THR,
                        ts_dev->coordinate_readouts * 2 + 2 - 1);

        input_dev->name = "ti-tsc";
        input_dev->dev.parent = &pdev->dev;

        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
        input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

        input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
        input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);

        /* register to the input system */
        err = input_register_device(input_dev);
        if (err)
                goto err_free_irq;

        platform_set_drvdata(pdev, ts_dev);
        return 0;

err_free_irq:
        dev_pm_clear_wake_irq(&pdev->dev);
        device_init_wakeup(&pdev->dev, false);
        free_irq(ts_dev->irq, ts_dev);
err_free_mem:
        input_free_device(input_dev);
        kfree(ts_dev);
        return err;
}

static void titsc_remove(struct platform_device *pdev)
{
        struct titsc *ts_dev = platform_get_drvdata(pdev);
        u32 steps;

        dev_pm_clear_wake_irq(&pdev->dev);
        device_init_wakeup(&pdev->dev, false);
        free_irq(ts_dev->irq, ts_dev);

        /* total steps followed by the enable mask */
        steps = 2 * ts_dev->coordinate_readouts + 2;
        steps = (1 << steps) - 1;
        am335x_tsc_se_clr(ts_dev->mfd_tscadc, steps);

        input_unregister_device(ts_dev->input);

        kfree(ts_dev);
}

static int titsc_suspend(struct device *dev)
{
        struct titsc *ts_dev = dev_get_drvdata(dev);
        unsigned int idle;

        if (device_may_wakeup(dev)) {
                titsc_writel(ts_dev, REG_IRQSTATUS, TSC_IRQENB_MASK);
                idle = titsc_readl(ts_dev, REG_IRQENABLE);
                titsc_writel(ts_dev, REG_IRQENABLE,
                                (idle | IRQENB_HW_PEN));
                titsc_writel(ts_dev, REG_IRQWAKEUP, IRQWKUP_ENB);
        }
        return 0;
}

static int titsc_resume(struct device *dev)
{
        struct titsc *ts_dev = dev_get_drvdata(dev);

        if (device_may_wakeup(dev)) {
                titsc_writel(ts_dev, REG_IRQWAKEUP,
                                0x00);
                titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
                pm_relax(dev);
        }
        titsc_step_config(ts_dev);
        titsc_writel(ts_dev, REG_FIFO0THR,
                        ts_dev->coordinate_readouts * 2 + 2 - 1);
        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(titsc_pm_ops, titsc_suspend, titsc_resume);

static const struct of_device_id ti_tsc_dt_ids[] = {
        { .compatible = "ti,am3359-tsc", },
        { }
};
MODULE_DEVICE_TABLE(of, ti_tsc_dt_ids);

static struct platform_driver ti_tsc_driver = {
        .probe  = titsc_probe,
        .remove = titsc_remove,
        .driver = {
                .name   = "TI-am335x-tsc",
                .pm     = pm_sleep_ptr(&titsc_pm_ops),
                .of_match_table = ti_tsc_dt_ids,
        },
};
module_platform_driver(ti_tsc_driver);

MODULE_DESCRIPTION("TI touchscreen controller driver");
MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
MODULE_LICENSE("GPL");