/*
 * Freescale i.MX28 LRADC driver
 *
 * Copyright (c) 2012 DENX Software Engineering, GmbH.
 * Marek Vasut <marex@denx.de>
 *
 * 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.
 */

#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/sysfs.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/stmp_device.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/clk.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#define DRIVER_NAME             "mxs-lradc"

#define LRADC_MAX_DELAY_CHANS   4
#define LRADC_MAX_MAPPED_CHANS  8
#define LRADC_MAX_TOTAL_CHANS   16

#define LRADC_DELAY_TIMER_HZ    2000

/*
 * Make this runtime configurable if necessary. Currently, if the buffered mode
 * is enabled, the LRADC takes LRADC_DELAY_TIMER_LOOP samples of data before
 * triggering IRQ. The sampling happens every (LRADC_DELAY_TIMER_PER / 2000)
 * seconds. The result is that the samples arrive every 500mS.
 */
#define LRADC_DELAY_TIMER_PER   200
#define LRADC_DELAY_TIMER_LOOP  5

/*
 * Once the pen touches the touchscreen, the touchscreen switches from
 * IRQ-driven mode to polling mode to prevent interrupt storm. The polling
 * is realized by worker thread, which is called every 20 or so milliseconds.
 * This gives the touchscreen enough fluence and does not strain the system
 * too much.
 */
#define LRADC_TS_SAMPLE_DELAY_MS        5

/*
 * The LRADC reads the following amount of samples from each touchscreen
 * channel and the driver then computes avarage of these.
 */
#define LRADC_TS_SAMPLE_AMOUNT          4

enum mxs_lradc_id {
        IMX23_LRADC,
        IMX28_LRADC,
};

static const char * const mx23_lradc_irq_names[] = {
        "mxs-lradc-touchscreen",
        "mxs-lradc-channel0",
        "mxs-lradc-channel1",
        "mxs-lradc-channel2",
        "mxs-lradc-channel3",
        "mxs-lradc-channel4",
        "mxs-lradc-channel5",
        "mxs-lradc-channel6",
        "mxs-lradc-channel7",
};

static const char * const mx28_lradc_irq_names[] = {
        "mxs-lradc-touchscreen",
        "mxs-lradc-thresh0",
        "mxs-lradc-thresh1",
        "mxs-lradc-channel0",
        "mxs-lradc-channel1",
        "mxs-lradc-channel2",
        "mxs-lradc-channel3",
        "mxs-lradc-channel4",
        "mxs-lradc-channel5",
        "mxs-lradc-channel6",
        "mxs-lradc-channel7",
        "mxs-lradc-button0",
        "mxs-lradc-button1",
};

struct mxs_lradc_of_config {
        const int               irq_count;
        const char * const      *irq_name;
        const uint32_t          *vref_mv;
};

#define VREF_MV_BASE 1850

static const uint32_t mx23_vref_mv[LRADC_MAX_TOTAL_CHANS] = {
        VREF_MV_BASE,           /* CH0 */
        VREF_MV_BASE,           /* CH1 */
        VREF_MV_BASE,           /* CH2 */
        VREF_MV_BASE,           /* CH3 */
        VREF_MV_BASE,           /* CH4 */
        VREF_MV_BASE,           /* CH5 */
        VREF_MV_BASE * 2,       /* CH6 VDDIO */
        VREF_MV_BASE * 4,       /* CH7 VBATT */
        VREF_MV_BASE,           /* CH8 Temp sense 0 */
        VREF_MV_BASE,           /* CH9 Temp sense 1 */
        VREF_MV_BASE,           /* CH10 */
        VREF_MV_BASE,           /* CH11 */
        VREF_MV_BASE,           /* CH12 USB_DP */
        VREF_MV_BASE,           /* CH13 USB_DN */
        VREF_MV_BASE,           /* CH14 VBG */
        VREF_MV_BASE * 4,       /* CH15 VDD5V */
};

static const uint32_t mx28_vref_mv[LRADC_MAX_TOTAL_CHANS] = {
        VREF_MV_BASE,           /* CH0 */
        VREF_MV_BASE,           /* CH1 */
        VREF_MV_BASE,           /* CH2 */
        VREF_MV_BASE,           /* CH3 */
        VREF_MV_BASE,           /* CH4 */
        VREF_MV_BASE,           /* CH5 */
        VREF_MV_BASE,           /* CH6 */
        VREF_MV_BASE * 4,       /* CH7 VBATT */
        VREF_MV_BASE,           /* CH8 Temp sense 0 */
        VREF_MV_BASE,           /* CH9 Temp sense 1 */
        VREF_MV_BASE * 2,       /* CH10 VDDIO */
        VREF_MV_BASE,           /* CH11 VTH */
        VREF_MV_BASE * 2,       /* CH12 VDDA */
        VREF_MV_BASE,           /* CH13 VDDD */
        VREF_MV_BASE,           /* CH14 VBG */
        VREF_MV_BASE * 4,       /* CH15 VDD5V */
};

static const struct mxs_lradc_of_config mxs_lradc_of_config[] = {
        [IMX23_LRADC] = {
                .irq_count      = ARRAY_SIZE(mx23_lradc_irq_names),
                .irq_name       = mx23_lradc_irq_names,
                .vref_mv        = mx23_vref_mv,
        },
        [IMX28_LRADC] = {
                .irq_count      = ARRAY_SIZE(mx28_lradc_irq_names),
                .irq_name       = mx28_lradc_irq_names,
                .vref_mv        = mx28_vref_mv,
        },
};

enum mxs_lradc_ts {
        MXS_LRADC_TOUCHSCREEN_NONE = 0,
        MXS_LRADC_TOUCHSCREEN_4WIRE,
        MXS_LRADC_TOUCHSCREEN_5WIRE,
};

/*
 * Touchscreen handling
 */
enum lradc_ts_plate {
        LRADC_TOUCH = 0,
        LRADC_SAMPLE_X,
        LRADC_SAMPLE_Y,
        LRADC_SAMPLE_PRESSURE,
        LRADC_SAMPLE_VALID,
};

enum mxs_lradc_divbytwo {
        MXS_LRADC_DIV_DISABLED = 0,
        MXS_LRADC_DIV_ENABLED,
};

struct mxs_lradc_scale {
        unsigned int            integer;
        unsigned int            nano;
};

struct mxs_lradc {
        struct device           *dev;
        void __iomem            *base;
        int                     irq[13];

        struct clk              *clk;

        uint32_t                *buffer;
        struct iio_trigger      *trig;

        struct mutex            lock;

        struct completion       completion;

        const uint32_t          *vref_mv;
        struct mxs_lradc_scale  scale_avail[LRADC_MAX_TOTAL_CHANS][2];
        unsigned long           is_divided;

        /*
         * When the touchscreen is enabled, we give it two private virtual
         * channels: #6 and #7. This means that only 6 virtual channels (instead
         * of 8) will be available for buffered capture.
         */
#define TOUCHSCREEN_VCHANNEL1           7
#define TOUCHSCREEN_VCHANNEL2           6
#define BUFFER_VCHANS_LIMITED           0x3f
#define BUFFER_VCHANS_ALL               0xff
        u8                      buffer_vchans;

        /*
         * Furthermore, certain LRADC channels are shared between touchscreen
         * and/or touch-buttons and generic LRADC block. Therefore when using
         * either of these, these channels are not available for the regular
         * sampling. The shared channels are as follows:
         *
         * CH0 -- Touch button #0
         * CH1 -- Touch button #1
         * CH2 -- Touch screen XPUL
         * CH3 -- Touch screen YPLL
         * CH4 -- Touch screen XNUL
         * CH5 -- Touch screen YNLR
         * CH6 -- Touch screen WIPER (5-wire only)
         *
         * The bitfields below represents which parts of the LRADC block are
         * switched into special mode of operation. These channels can not
         * be sampled as regular LRADC channels. The driver will refuse any
         * attempt to sample these channels.
         */
#define CHAN_MASK_TOUCHBUTTON           (BIT(1) | BIT(0))
#define CHAN_MASK_TOUCHSCREEN_4WIRE     (0xf << 2)
#define CHAN_MASK_TOUCHSCREEN_5WIRE     (0x1f << 2)
        enum mxs_lradc_ts       use_touchscreen;
        bool                    use_touchbutton;

        struct input_dev        *ts_input;

        enum mxs_lradc_id       soc;
        enum lradc_ts_plate     cur_plate; /* statemachine */
        bool                    ts_valid;
        unsigned                ts_x_pos;
        unsigned                ts_y_pos;
        unsigned                ts_pressure;

        /* handle touchscreen's physical behaviour */
        /* samples per coordinate */
        unsigned                over_sample_cnt;
        /* time clocks between samples */
        unsigned                over_sample_delay;
        /* time in clocks to wait after the plates where switched */
        unsigned                settling_delay;
};

#define LRADC_CTRL0                             0x00
# define LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE   BIT(23)
# define LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE     BIT(22)
# define LRADC_CTRL0_MX28_YNNSW /* YM */        BIT(21)
# define LRADC_CTRL0_MX28_YPNSW /* YP */        BIT(20)
# define LRADC_CTRL0_MX28_YPPSW /* YP */        BIT(19)
# define LRADC_CTRL0_MX28_XNNSW /* XM */        BIT(18)
# define LRADC_CTRL0_MX28_XNPSW /* XM */        BIT(17)
# define LRADC_CTRL0_MX28_XPPSW /* XP */        BIT(16)

# define LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE   BIT(20)
# define LRADC_CTRL0_MX23_YM                    BIT(19)
# define LRADC_CTRL0_MX23_XM                    BIT(18)
# define LRADC_CTRL0_MX23_YP                    BIT(17)
# define LRADC_CTRL0_MX23_XP                    BIT(16)

# define LRADC_CTRL0_MX28_PLATE_MASK \
                (LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE | \
                LRADC_CTRL0_MX28_YNNSW | LRADC_CTRL0_MX28_YPNSW | \
                LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW | \
                LRADC_CTRL0_MX28_XNPSW | LRADC_CTRL0_MX28_XPPSW)

# define LRADC_CTRL0_MX23_PLATE_MASK \
                (LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE | \
                LRADC_CTRL0_MX23_YM | LRADC_CTRL0_MX23_XM | \
                LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XP)

#define LRADC_CTRL1                             0x10
#define LRADC_CTRL1_TOUCH_DETECT_IRQ_EN         BIT(24)
#define LRADC_CTRL1_LRADC_IRQ_EN(n)             (1 << ((n) + 16))
#define LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK      (0x1fff << 16)
#define LRADC_CTRL1_MX23_LRADC_IRQ_EN_MASK      (0x01ff << 16)
#define LRADC_CTRL1_LRADC_IRQ_EN_OFFSET         16
#define LRADC_CTRL1_TOUCH_DETECT_IRQ            BIT(8)
#define LRADC_CTRL1_LRADC_IRQ(n)                (1 << (n))
#define LRADC_CTRL1_MX28_LRADC_IRQ_MASK         0x1fff
#define LRADC_CTRL1_MX23_LRADC_IRQ_MASK         0x01ff
#define LRADC_CTRL1_LRADC_IRQ_OFFSET            0

#define LRADC_CTRL2                             0x20
#define LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET        24
#define LRADC_CTRL2_TEMPSENSE_PWD               BIT(15)

#define LRADC_STATUS                            0x40
#define LRADC_STATUS_TOUCH_DETECT_RAW           BIT(0)

#define LRADC_CH(n)                             (0x50 + (0x10 * (n)))
#define LRADC_CH_ACCUMULATE                     BIT(29)
#define LRADC_CH_NUM_SAMPLES_MASK               (0x1f << 24)
#define LRADC_CH_NUM_SAMPLES_OFFSET             24
#define LRADC_CH_NUM_SAMPLES(x) \
                                ((x) << LRADC_CH_NUM_SAMPLES_OFFSET)
#define LRADC_CH_VALUE_MASK                     0x3ffff
#define LRADC_CH_VALUE_OFFSET                   0

#define LRADC_DELAY(n)                          (0xd0 + (0x10 * (n)))
#define LRADC_DELAY_TRIGGER_LRADCS_MASK         (0xff << 24)
#define LRADC_DELAY_TRIGGER_LRADCS_OFFSET       24
#define LRADC_DELAY_TRIGGER(x) \
                                (((x) << LRADC_DELAY_TRIGGER_LRADCS_OFFSET) & \
                                LRADC_DELAY_TRIGGER_LRADCS_MASK)
#define LRADC_DELAY_KICK                        (1 << 20)
#define LRADC_DELAY_TRIGGER_DELAYS_MASK         (0xf << 16)
#define LRADC_DELAY_TRIGGER_DELAYS_OFFSET       16
#define LRADC_DELAY_TRIGGER_DELAYS(x) \
                                (((x) << LRADC_DELAY_TRIGGER_DELAYS_OFFSET) & \
                                LRADC_DELAY_TRIGGER_DELAYS_MASK)
#define LRADC_DELAY_LOOP_COUNT_MASK             (0x1f << 11)
#define LRADC_DELAY_LOOP_COUNT_OFFSET           11
#define LRADC_DELAY_LOOP(x) \
                                (((x) << LRADC_DELAY_LOOP_COUNT_OFFSET) & \
                                LRADC_DELAY_LOOP_COUNT_MASK)
#define LRADC_DELAY_DELAY_MASK                  0x7ff
#define LRADC_DELAY_DELAY_OFFSET                0
#define LRADC_DELAY_DELAY(x) \
                                (((x) << LRADC_DELAY_DELAY_OFFSET) & \
                                LRADC_DELAY_DELAY_MASK)

#define LRADC_CTRL4                             0x140
#define LRADC_CTRL4_LRADCSELECT_MASK(n)         (0xf << ((n) * 4))
#define LRADC_CTRL4_LRADCSELECT_OFFSET(n)       ((n) * 4)
#define LRADC_CTRL4_LRADCSELECT(n, x) \
                                (((x) << LRADC_CTRL4_LRADCSELECT_OFFSET(n)) & \
                                LRADC_CTRL4_LRADCSELECT_MASK(n))

#define LRADC_RESOLUTION                        12
#define LRADC_SINGLE_SAMPLE_MASK                ((1 << LRADC_RESOLUTION) - 1)

static void mxs_lradc_reg_set(struct mxs_lradc *lradc, u32 val, u32 reg)
{
        writel(val, lradc->base + reg + STMP_OFFSET_REG_SET);
}

static void mxs_lradc_reg_clear(struct mxs_lradc *lradc, u32 val, u32 reg)
{
        writel(val, lradc->base + reg + STMP_OFFSET_REG_CLR);
}

static void mxs_lradc_reg_wrt(struct mxs_lradc *lradc, u32 val, u32 reg)
{
        writel(val, lradc->base + reg);
}

static u32 mxs_lradc_plate_mask(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL0_MX23_PLATE_MASK;
        return LRADC_CTRL0_MX28_PLATE_MASK;
}

static u32 mxs_lradc_irq_en_mask(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL1_MX23_LRADC_IRQ_EN_MASK;
        return LRADC_CTRL1_MX28_LRADC_IRQ_EN_MASK;
}

static u32 mxs_lradc_irq_mask(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL1_MX23_LRADC_IRQ_MASK;
        return LRADC_CTRL1_MX28_LRADC_IRQ_MASK;
}

static u32 mxs_lradc_touch_detect_bit(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE;
        return LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE;
}

static u32 mxs_lradc_drive_x_plate(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL0_MX23_XP | LRADC_CTRL0_MX23_XM;
        return LRADC_CTRL0_MX28_XPPSW | LRADC_CTRL0_MX28_XNNSW;
}

static u32 mxs_lradc_drive_y_plate(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_YM;
        return LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_YNNSW;
}

static u32 mxs_lradc_drive_pressure(struct mxs_lradc *lradc)
{
        if (lradc->soc == IMX23_LRADC)
                return LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XM;
        return LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_XNNSW;
}

static bool mxs_lradc_check_touch_event(struct mxs_lradc *lradc)
{
        return !!(readl(lradc->base + LRADC_STATUS) &
                                        LRADC_STATUS_TOUCH_DETECT_RAW);
}

static void mxs_lradc_map_channel(struct mxs_lradc *lradc, unsigned vch,
                                  unsigned ch)
{
        mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(vch),
                                LRADC_CTRL4);
        mxs_lradc_reg_set(lradc, LRADC_CTRL4_LRADCSELECT(vch, ch), LRADC_CTRL4);
}

static void mxs_lradc_setup_ts_channel(struct mxs_lradc *lradc, unsigned ch)
{
        /*
         * prepare for oversampling conversion
         *
         * from the datasheet:
         * "The ACCUMULATE bit in the appropriate channel register
         * HW_LRADC_CHn must be set to 1 if NUM_SAMPLES is greater then 0;
         * otherwise, the IRQs will not fire."
         */
        mxs_lradc_reg_wrt(lradc, LRADC_CH_ACCUMULATE |
                        LRADC_CH_NUM_SAMPLES(lradc->over_sample_cnt - 1),
                        LRADC_CH(ch));

        /* from the datasheet:
         * "Software must clear this register in preparation for a
         * multi-cycle accumulation.
         */
        mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch));

        /*
         * prepare the delay/loop unit according to the oversampling count
         *
         * from the datasheet:
         * "The DELAY fields in HW_LRADC_DELAY0, HW_LRADC_DELAY1,
         * HW_LRADC_DELAY2, and HW_LRADC_DELAY3 must be non-zero; otherwise,
         * the LRADC will not trigger the delay group."
         */
        mxs_lradc_reg_wrt(lradc, LRADC_DELAY_TRIGGER(1 << ch) |
                LRADC_DELAY_TRIGGER_DELAYS(0) |
                LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) |
                LRADC_DELAY_DELAY(lradc->over_sample_delay - 1),
                        LRADC_DELAY(3));

        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(ch), LRADC_CTRL1);

        /*
         * after changing the touchscreen plates setting
         * the signals need some initial time to settle. Start the
         * SoC's delay unit and start the conversion later
         * and automatically.
         */
        mxs_lradc_reg_wrt(lradc,
                LRADC_DELAY_TRIGGER(0) | /* don't trigger ADC */
                LRADC_DELAY_TRIGGER_DELAYS(BIT(3)) | /* trigger DELAY unit#3 */
                LRADC_DELAY_KICK |
                LRADC_DELAY_DELAY(lradc->settling_delay),
                        LRADC_DELAY(2));
}

/*
 * Pressure detection is special:
 * We want to do both required measurements for the pressure detection in
 * one turn. Use the hardware features to chain both conversions and let the
 * hardware report one interrupt if both conversions are done
 */
static void mxs_lradc_setup_ts_pressure(struct mxs_lradc *lradc, unsigned ch1,
                                                        unsigned ch2)
{
        u32 reg;

        /*
         * prepare for oversampling conversion
         *
         * from the datasheet:
         * "The ACCUMULATE bit in the appropriate channel register
         * HW_LRADC_CHn must be set to 1 if NUM_SAMPLES is greater then 0;
         * otherwise, the IRQs will not fire."
         */
        reg = LRADC_CH_ACCUMULATE |
                LRADC_CH_NUM_SAMPLES(lradc->over_sample_cnt - 1);
        mxs_lradc_reg_wrt(lradc, reg, LRADC_CH(ch1));
        mxs_lradc_reg_wrt(lradc, reg, LRADC_CH(ch2));

        /* from the datasheet:
         * "Software must clear this register in preparation for a
         * multi-cycle accumulation.
         */
        mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch1));
        mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch2));

        /* prepare the delay/loop unit according to the oversampling count */
        mxs_lradc_reg_wrt(lradc, LRADC_DELAY_TRIGGER(1 << ch1) |
                LRADC_DELAY_TRIGGER(1 << ch2) | /* start both channels */
                LRADC_DELAY_TRIGGER_DELAYS(0) |
                LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) |
                LRADC_DELAY_DELAY(lradc->over_sample_delay - 1),
                                        LRADC_DELAY(3));

        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ(ch2), LRADC_CTRL1);

        /*
         * after changing the touchscreen plates setting
         * the signals need some initial time to settle. Start the
         * SoC's delay unit and start the conversion later
         * and automatically.
         */
        mxs_lradc_reg_wrt(lradc,
                LRADC_DELAY_TRIGGER(0) | /* don't trigger ADC */
                LRADC_DELAY_TRIGGER_DELAYS(BIT(3)) | /* trigger DELAY unit#3 */
                LRADC_DELAY_KICK |
                LRADC_DELAY_DELAY(lradc->settling_delay), LRADC_DELAY(2));
}

static unsigned mxs_lradc_read_raw_channel(struct mxs_lradc *lradc,
                                                        unsigned channel)
{
        u32 reg;
        unsigned num_samples, val;

        reg = readl(lradc->base + LRADC_CH(channel));
        if (reg & LRADC_CH_ACCUMULATE)
                num_samples = lradc->over_sample_cnt;
        else
                num_samples = 1;

        val = (reg & LRADC_CH_VALUE_MASK) >> LRADC_CH_VALUE_OFFSET;
        return val / num_samples;
}

static unsigned mxs_lradc_read_ts_pressure(struct mxs_lradc *lradc,
                                                unsigned ch1, unsigned ch2)
{
        u32 reg, mask;
        unsigned pressure, m1, m2;

        mask = LRADC_CTRL1_LRADC_IRQ(ch1) | LRADC_CTRL1_LRADC_IRQ(ch2);
        reg = readl(lradc->base + LRADC_CTRL1) & mask;

        while (reg != mask) {
                reg = readl(lradc->base + LRADC_CTRL1) & mask;
                dev_dbg(lradc->dev, "One channel is still busy: %X\n", reg);
        }

        m1 = mxs_lradc_read_raw_channel(lradc, ch1);
        m2 = mxs_lradc_read_raw_channel(lradc, ch2);

        if (m2 == 0) {
                dev_warn(lradc->dev, "Cannot calculate pressure\n");
                return 1 << (LRADC_RESOLUTION - 1);
        }

        /* simply scale the value from 0 ... max ADC resolution */
        pressure = m1;
        pressure *= (1 << LRADC_RESOLUTION);
        pressure /= m2;

        dev_dbg(lradc->dev, "Pressure = %u\n", pressure);
        return pressure;
}

#define TS_CH_XP 2
#define TS_CH_YP 3
#define TS_CH_XM 4
#define TS_CH_YM 5

/*
 * YP(open)--+-------------+
 *           |             |--+
 *           |             |  |
 *    YM(-)--+-------------+  |
 *             +--------------+
 *             |              |
 *         XP(weak+)        XM(open)
 *
 * "weak+" means 200k Ohm VDDIO
 * (-) means GND
 */
static void mxs_lradc_setup_touch_detection(struct mxs_lradc *lradc)
{
        /*
         * In order to detect a touch event the 'touch detect enable' bit
         * enables:
         *  - a weak pullup to the X+ connector
         *  - a strong ground at the Y- connector
         */
        mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
        mxs_lradc_reg_set(lradc, mxs_lradc_touch_detect_bit(lradc),
                                LRADC_CTRL0);
}

/*
 * YP(meas)--+-------------+
 *           |             |--+
 *           |             |  |
 * YM(open)--+-------------+  |
 *             +--------------+
 *             |              |
 *           XP(+)          XM(-)
 *
 * (+) means here 1.85 V
 * (-) means here GND
 */
static void mxs_lradc_prepare_x_pos(struct mxs_lradc *lradc)
{
        mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
        mxs_lradc_reg_set(lradc, mxs_lradc_drive_x_plate(lradc), LRADC_CTRL0);

        lradc->cur_plate = LRADC_SAMPLE_X;
        mxs_lradc_map_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_YP);
        mxs_lradc_setup_ts_channel(lradc, TOUCHSCREEN_VCHANNEL1);
}

/*
 *   YP(+)--+-------------+
 *          |             |--+
 *          |             |  |
 *   YM(-)--+-------------+  |
 *            +--------------+
 *            |              |
 *         XP(open)        XM(meas)
 *
 * (+) means here 1.85 V
 * (-) means here GND
 */
static void mxs_lradc_prepare_y_pos(struct mxs_lradc *lradc)
{
        mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
        mxs_lradc_reg_set(lradc, mxs_lradc_drive_y_plate(lradc), LRADC_CTRL0);

        lradc->cur_plate = LRADC_SAMPLE_Y;
        mxs_lradc_map_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_XM);
        mxs_lradc_setup_ts_channel(lradc, TOUCHSCREEN_VCHANNEL1);
}

/*
 *    YP(+)--+-------------+
 *           |             |--+
 *           |             |  |
 * YM(meas)--+-------------+  |
 *             +--------------+
 *             |              |
 *          XP(meas)        XM(-)
 *
 * (+) means here 1.85 V
 * (-) means here GND
 */
static void mxs_lradc_prepare_pressure(struct mxs_lradc *lradc)
{
        mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
        mxs_lradc_reg_set(lradc, mxs_lradc_drive_pressure(lradc), LRADC_CTRL0);

        lradc->cur_plate = LRADC_SAMPLE_PRESSURE;
        mxs_lradc_map_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_YM);
        mxs_lradc_map_channel(lradc, TOUCHSCREEN_VCHANNEL2, TS_CH_XP);
        mxs_lradc_setup_ts_pressure(lradc, TOUCHSCREEN_VCHANNEL2,
                                                TOUCHSCREEN_VCHANNEL1);
}

static void mxs_lradc_enable_touch_detection(struct mxs_lradc *lradc)
{
        mxs_lradc_setup_touch_detection(lradc);

        lradc->cur_plate = LRADC_TOUCH;
        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ |
                                LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
        mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
}

static void mxs_lradc_start_touch_event(struct mxs_lradc *lradc)
{
        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
                                LRADC_CTRL1);
        mxs_lradc_reg_set(lradc,
                LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1), LRADC_CTRL1);
        /*
         * start with the Y-pos, because it uses nearly the same plate
         * settings like the touch detection
         */
        mxs_lradc_prepare_y_pos(lradc);
}

static void mxs_lradc_report_ts_event(struct mxs_lradc *lradc)
{
        input_report_abs(lradc->ts_input, ABS_X, lradc->ts_x_pos);
        input_report_abs(lradc->ts_input, ABS_Y, lradc->ts_y_pos);
        input_report_abs(lradc->ts_input, ABS_PRESSURE, lradc->ts_pressure);
        input_report_key(lradc->ts_input, BTN_TOUCH, 1);
        input_sync(lradc->ts_input);
}

static void mxs_lradc_complete_touch_event(struct mxs_lradc *lradc)
{
        mxs_lradc_setup_touch_detection(lradc);
        lradc->cur_plate = LRADC_SAMPLE_VALID;
        /*
         * start a dummy conversion to burn time to settle the signals
         * note: we are not interested in the conversion's value
         */
        mxs_lradc_reg_wrt(lradc, 0, LRADC_CH(TOUCHSCREEN_VCHANNEL1));
        mxs_lradc_reg_clear(lradc,
                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1) |
                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL2), LRADC_CTRL1);
        mxs_lradc_reg_wrt(lradc,
                LRADC_DELAY_TRIGGER(1 << TOUCHSCREEN_VCHANNEL1) |
                LRADC_DELAY_KICK | LRADC_DELAY_DELAY(10), /* waste 5 ms */
                        LRADC_DELAY(2));
}

/*
 * in order to avoid false measurements, report only samples where
 * the surface is still touched after the position measurement
 */
static void mxs_lradc_finish_touch_event(struct mxs_lradc *lradc, bool valid)
{
        /* if it is still touched, report the sample */
        if (valid && mxs_lradc_check_touch_event(lradc)) {
                lradc->ts_valid = true;
                mxs_lradc_report_ts_event(lradc);
        }

        /* if it is even still touched, continue with the next measurement */
        if (mxs_lradc_check_touch_event(lradc)) {
                mxs_lradc_prepare_y_pos(lradc);
                return;
        }

        if (lradc->ts_valid) {
                /* signal the release */
                lradc->ts_valid = false;
                input_report_key(lradc->ts_input, BTN_TOUCH, 0);
                input_sync(lradc->ts_input);
        }

        /* if it is released, wait for the next touch via IRQ */
        lradc->cur_plate = LRADC_TOUCH;
        mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(2));
        mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(3));
        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ |
                LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1) |
                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1), LRADC_CTRL1);
        mxs_lradc_reg_set(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
}

/* touchscreen's state machine */
static void mxs_lradc_handle_touch(struct mxs_lradc *lradc)
{
        switch (lradc->cur_plate) {
        case LRADC_TOUCH:
                if (mxs_lradc_check_touch_event(lradc))
                        mxs_lradc_start_touch_event(lradc);
                mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ,
                                        LRADC_CTRL1);
                return;

        case LRADC_SAMPLE_Y:
                lradc->ts_y_pos = mxs_lradc_read_raw_channel(lradc,
                                                        TOUCHSCREEN_VCHANNEL1);
                mxs_lradc_prepare_x_pos(lradc);
                return;

        case LRADC_SAMPLE_X:
                lradc->ts_x_pos = mxs_lradc_read_raw_channel(lradc,
                                                        TOUCHSCREEN_VCHANNEL1);
                mxs_lradc_prepare_pressure(lradc);
                return;

        case LRADC_SAMPLE_PRESSURE:
                lradc->ts_pressure = mxs_lradc_read_ts_pressure(lradc,
                                                        TOUCHSCREEN_VCHANNEL2,
                                                        TOUCHSCREEN_VCHANNEL1);
                mxs_lradc_complete_touch_event(lradc);
                return;

        case LRADC_SAMPLE_VALID:
                mxs_lradc_finish_touch_event(lradc, 1);
                break;
        }
}

/*
 * Raw I/O operations
 */
static int mxs_lradc_read_single(struct iio_dev *iio_dev, int chan, int *val)
{
        struct mxs_lradc *lradc = iio_priv(iio_dev);
        int ret;

        /*
         * See if there is no buffered operation in progess. If there is, simply
         * bail out. This can be improved to support both buffered and raw IO at
         * the same time, yet the code becomes horribly complicated. Therefore I
         * applied KISS principle here.
         */
        ret = mutex_trylock(&lradc->lock);
        if (!ret)
                return -EBUSY;

        reinit_completion(&lradc->completion);

        /*
         * No buffered operation in progress, map the channel and trigger it.
         * Virtual channel 0 is always used here as the others are always not
         * used if doing raw sampling.
         */
        if (lradc->soc == IMX28_LRADC)
                mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0),
                        LRADC_CTRL1);
        mxs_lradc_reg_clear(lradc, 0x1, LRADC_CTRL0);

        /* Enable / disable the divider per requirement */
        if (test_bit(chan, &lradc->is_divided))
                mxs_lradc_reg_set(lradc, 1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET,
                        LRADC_CTRL2);
        else
                mxs_lradc_reg_clear(lradc,
                        1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET, LRADC_CTRL2);

        /* Clean the slot's previous content, then set new one. */
        mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(0),
                        LRADC_CTRL4);
        mxs_lradc_reg_set(lradc, chan, LRADC_CTRL4);

        mxs_lradc_reg_wrt(lradc, 0, LRADC_CH(0));

        /* Enable the IRQ and start sampling the channel. */
        mxs_lradc_reg_set(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0), LRADC_CTRL1);
        mxs_lradc_reg_set(lradc, BIT(0), LRADC_CTRL0);

        /* Wait for completion on the channel, 1 second max. */
        ret = wait_for_completion_killable_timeout(&lradc->completion, HZ);
        if (!ret)
                ret = -ETIMEDOUT;
        if (ret < 0)
                goto err;

        /* Read the data. */
        *val = readl(lradc->base + LRADC_CH(0)) & LRADC_CH_VALUE_MASK;
        ret = IIO_VAL_INT;

err:
        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_LRADC_IRQ_EN(0), LRADC_CTRL1);

        mutex_unlock(&lradc->lock);

        return ret;
}

static int mxs_lradc_read_temp(struct iio_dev *iio_dev, int *val)
{
        int ret, min, max;

        ret = mxs_lradc_read_single(iio_dev, 8, &min);
        if (ret != IIO_VAL_INT)
                return ret;

        ret = mxs_lradc_read_single(iio_dev, 9, &max);
        if (ret != IIO_VAL_INT)
                return ret;

        *val = max - min;

        return IIO_VAL_INT;
}

static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
                        const struct iio_chan_spec *chan,
                        int *val, int *val2, long m)
{
        struct mxs_lradc *lradc = iio_priv(iio_dev);

        switch (m) {
        case IIO_CHAN_INFO_RAW:
                if (chan->type == IIO_TEMP)
                        return mxs_lradc_read_temp(iio_dev, val);

                return mxs_lradc_read_single(iio_dev, chan->channel, val);

        case IIO_CHAN_INFO_SCALE:
                if (chan->type == IIO_TEMP) {
                        /* From the datasheet, we have to multiply by 1.012 and
                         * divide by 4
                         */
                        *val = 0;
                        *val2 = 253000;
                        return IIO_VAL_INT_PLUS_MICRO;
                }

                *val = lradc->vref_mv[chan->channel];
                *val2 = chan->scan_type.realbits -
                        test_bit(chan->channel, &lradc->is_divided);
                return IIO_VAL_FRACTIONAL_LOG2;

        case IIO_CHAN_INFO_OFFSET:
                if (chan->type == IIO_TEMP) {
                        /* The calculated value from the ADC is in Kelvin, we
                         * want Celsius for hwmon so the offset is
                         * -272.15 * scale
                         */
                        *val = -1075;
                        *val2 = 691699;

                        return IIO_VAL_INT_PLUS_MICRO;
                }

                return -EINVAL;

        default:
                break;
        }

        return -EINVAL;
}

static int mxs_lradc_write_raw(struct iio_dev *iio_dev,
                               const struct iio_chan_spec *chan,
                               int val, int val2, long m)
{
        struct mxs_lradc *lradc = iio_priv(iio_dev);
        struct mxs_lradc_scale *scale_avail =
                        lradc->scale_avail[chan->channel];
        int ret;

        ret = mutex_trylock(&lradc->lock);
        if (!ret)
                return -EBUSY;

        switch (m) {
        case IIO_CHAN_INFO_SCALE:
                ret = -EINVAL;
                if (val == scale_avail[MXS_LRADC_DIV_DISABLED].integer &&
                    val2 == scale_avail[MXS_LRADC_DIV_DISABLED].nano) {
                        /* divider by two disabled */
                        clear_bit(chan->channel, &lradc->is_divided);
                        ret = 0;
                } else if (val == scale_avail[MXS_LRADC_DIV_ENABLED].integer &&
                           val2 == scale_avail[MXS_LRADC_DIV_ENABLED].nano) {
                        /* divider by two enabled */
                        set_bit(chan->channel, &lradc->is_divided);
                        ret = 0;
                }

                break;
        default:
                ret = -EINVAL;
                break;
        }

        mutex_unlock(&lradc->lock);

        return ret;
}

static int mxs_lradc_write_raw_get_fmt(struct iio_dev *iio_dev,
                                       const struct iio_chan_spec *chan,
                                       long m)
{
        return IIO_VAL_INT_PLUS_NANO;
}

static ssize_t mxs_lradc_show_scale_available_ch(struct device *dev,
                struct device_attribute *attr,
                char *buf,
                int ch)
{
        struct iio_dev *iio = dev_to_iio_dev(dev);
        struct mxs_lradc *lradc = iio_priv(iio);
        int i, len = 0;

        for (i = 0; i < ARRAY_SIZE(lradc->scale_avail[ch]); i++)
                len += sprintf(buf + len, "%u.%09u ",
                               lradc->scale_avail[ch][i].integer,
                               lradc->scale_avail[ch][i].nano);

        len += sprintf(buf + len, "\n");

        return len;
}

static ssize_t mxs_lradc_show_scale_available(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
        struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);

        return mxs_lradc_show_scale_available_ch(dev, attr, buf,
                                                 iio_attr->address);
}

#define SHOW_SCALE_AVAILABLE_ATTR(ch)                                   \
static IIO_DEVICE_ATTR(in_voltage##ch##_scale_available, S_IRUGO,       \
                       mxs_lradc_show_scale_available, NULL, ch)

SHOW_SCALE_AVAILABLE_ATTR(0);
SHOW_SCALE_AVAILABLE_ATTR(1);
SHOW_SCALE_AVAILABLE_ATTR(2);
SHOW_SCALE_AVAILABLE_ATTR(3);
SHOW_SCALE_AVAILABLE_ATTR(4);
SHOW_SCALE_AVAILABLE_ATTR(5);
SHOW_SCALE_AVAILABLE_ATTR(6);
SHOW_SCALE_AVAILABLE_ATTR(7);
SHOW_SCALE_AVAILABLE_ATTR(10);
SHOW_SCALE_AVAILABLE_ATTR(11);
SHOW_SCALE_AVAILABLE_ATTR(12);
SHOW_SCALE_AVAILABLE_ATTR(13);
SHOW_SCALE_AVAILABLE_ATTR(14);
SHOW_SCALE_AVAILABLE_ATTR(15);

static struct attribute *mxs_lradc_attributes[] = {
        &iio_dev_attr_in_voltage0_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage1_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage2_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage3_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage4_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage5_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage6_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage7_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage10_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage11_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage12_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage13_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage14_scale_available.dev_attr.attr,
        &iio_dev_attr_in_voltage15_scale_available.dev_attr.attr,
        NULL
};

static const struct attribute_group mxs_lradc_attribute_group = {
        .attrs = mxs_lradc_attributes,
};

static const struct iio_info mxs_lradc_iio_info = {
        .driver_module          = THIS_MODULE,
        .read_raw               = mxs_lradc_read_raw,
        .write_raw              = mxs_lradc_write_raw,
        .write_raw_get_fmt      = mxs_lradc_write_raw_get_fmt,
        .attrs                  = &mxs_lradc_attribute_group,
};

static int mxs_lradc_ts_open(struct input_dev *dev)
{
        struct mxs_lradc *lradc = input_get_drvdata(dev);

        /* Enable the touch-detect circuitry. */
        mxs_lradc_enable_touch_detection(lradc);

        return 0;
}

static void mxs_lradc_disable_ts(struct mxs_lradc *lradc)
{
        /* stop all interrupts from firing */
        mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
                LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1) |
                LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL2), LRADC_CTRL1);

        /* Power-down touchscreen touch-detect circuitry. */
        mxs_lradc_reg_clear(lradc, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
}

static void mxs_lradc_ts_close(struct input_dev *dev)
{
        struct mxs_lradc *lradc = input_get_drvdata(dev);

        mxs_lradc_disable_ts(lradc);
}

static int mxs_lradc_ts_register(struct mxs_lradc *lradc)
{
        struct input_dev *input;
        struct device *dev = lradc->dev;
        int ret;

        if (!lradc->use_touchscreen)
                return 0;

        input = input_allocate_device();
        if (!input)
                return -ENOMEM;

        input->name = DRIVER_NAME;
        input->id.bustype = BUS_HOST;
        input->dev.parent = dev;
        input->open = mxs_lradc_ts_open;
        input->close = mxs_lradc_ts_close;

        __set_bit(EV_ABS, input->evbit);
        __set_bit(EV_KEY, input->evbit);
        __set_bit(BTN_TOUCH, input->keybit);
        input_set_abs_params(input, ABS_X, 0, LRADC_SINGLE_SAMPLE_MASK, 0, 0);
        input_set_abs_params(input, ABS_Y, 0, LRADC_SINGLE_SAMPLE_MASK, 0, 0);
        input_set_abs_params(input, ABS_PRESSURE, 0, LRADC_SINGLE_SAMPLE_MASK,
                             0, 0);

        lradc->ts_input = input;
        input_set_drvdata(input, lradc);
        ret = input_register_device(input);
        if (ret)
                input_free_device(lradc->ts_input);

        return ret;
}

static void mxs_lradc_ts_unregister(struct mxs_lradc *lradc)
{
        if (!lradc->use_touchscreen)
                return;

        mxs_lradc_disable_ts(lradc);
        input_unregister_device(lradc->ts_input);
}

/*
 * IRQ Handling
 */
static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
{
        struct iio_dev *iio = data;
        struct mxs_lradc *lradc = iio_priv(iio);
        unsigned long reg = readl(lradc->base + LRADC_CTRL1);
        uint32_t clr_irq = mxs_lradc_irq_mask(lradc);
        const uint32_t ts_irq_mask =
                LRADC_CTRL1_TOUCH_DETECT_IRQ |
                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1) |
                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL2);

        if (!(reg & mxs_lradc_irq_mask(lradc)))
                return IRQ_NONE;

        if (lradc->use_touchscreen && (reg & ts_irq_mask)) {
                mxs_lradc_handle_touch(lradc);

                /* Make sure we don't clear the next conversion's interrupt. */
                clr_irq &= ~(LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1) |
                                LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL2));
        }

        if (iio_buffer_enabled(iio)) {
                if (reg & lradc->buffer_vchans)
                        iio_trigger_poll(iio->trig);
        } else if (reg & LRADC_CTRL1_LRADC_IRQ(0)) {
                complete(&lradc->completion);
        }

        mxs_lradc_reg_clear(lradc, reg & clr_irq, LRADC_CTRL1);

        return IRQ_HANDLED;
}

/*
 * Trigger handling
 */
static irqreturn_t mxs_lradc_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *iio = pf->indio_dev;
        struct mxs_lradc *lradc = iio_priv(iio);
        const uint32_t chan_value = LRADC_CH_ACCUMULATE |
                ((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
        unsigned int i, j = 0;

        for_each_set_bit(i, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
                lradc->buffer[j] = readl(lradc->base + LRADC_CH(j));
                mxs_lradc_reg_wrt(lradc, chan_value, LRADC_CH(j));
                lradc->buffer[j] &= LRADC_CH_VALUE_MASK;
                lradc->buffer[j] /= LRADC_DELAY_TIMER_LOOP;
                j++;
        }

        iio_push_to_buffers_with_timestamp(iio, lradc->buffer, pf->timestamp);

        iio_trigger_notify_done(iio->trig);

        return IRQ_HANDLED;
}

static int mxs_lradc_configure_trigger(struct iio_trigger *trig, bool state)
{
        struct iio_dev *iio = iio_trigger_get_drvdata(trig);
        struct mxs_lradc *lradc = iio_priv(iio);
        const uint32_t st = state ? STMP_OFFSET_REG_SET : STMP_OFFSET_REG_CLR;

        mxs_lradc_reg_wrt(lradc, LRADC_DELAY_KICK, LRADC_DELAY(0) + st);

        return 0;
}

static const struct iio_trigger_ops mxs_lradc_trigger_ops = {
        .owner = THIS_MODULE,
        .set_trigger_state = &mxs_lradc_configure_trigger,
};

static int mxs_lradc_trigger_init(struct iio_dev *iio)
{
        int ret;
        struct iio_trigger *trig;
        struct mxs_lradc *lradc = iio_priv(iio);

        trig = iio_trigger_alloc("%s-dev%i", iio->name, iio->id);
        if (trig == NULL)
                return -ENOMEM;

        trig->dev.parent = lradc->dev;
        iio_trigger_set_drvdata(trig, iio);
        trig->ops = &mxs_lradc_trigger_ops;

        ret = iio_trigger_register(trig);
        if (ret) {
                iio_trigger_free(trig);
                return ret;
        }

        lradc->trig = trig;

        return 0;
}

static void mxs_lradc_trigger_remove(struct iio_dev *iio)
{
        struct mxs_lradc *lradc = iio_priv(iio);

        iio_trigger_unregister(lradc->trig);
        iio_trigger_free(lradc->trig);
}

static int mxs_lradc_buffer_preenable(struct iio_dev *iio)
{
        struct mxs_lradc *lradc = iio_priv(iio);
        int ret = 0, chan, ofs = 0;
        unsigned long enable = 0;
        uint32_t ctrl4_set = 0;
        uint32_t ctrl4_clr = 0;
        uint32_t ctrl1_irq = 0;
        const uint32_t chan_value = LRADC_CH_ACCUMULATE |
                ((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
        const int len = bitmap_weight(iio->active_scan_mask,
                        LRADC_MAX_TOTAL_CHANS);

        if (!len)
                return -EINVAL;

        /*
         * Lock the driver so raw access can not be done during buffered
         * operation. This simplifies the code a lot.
         */
        ret = mutex_trylock(&lradc->lock);
        if (!ret)
                return -EBUSY;

        lradc->buffer = kmalloc_array(len, sizeof(*lradc->buffer), GFP_KERNEL);
        if (!lradc->buffer) {
                ret = -ENOMEM;
                goto err_mem;
        }

        if (lradc->soc == IMX28_LRADC)
                mxs_lradc_reg_clear(lradc,
                        lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
                        LRADC_CTRL1);
        mxs_lradc_reg_clear(lradc, lradc->buffer_vchans, LRADC_CTRL0);

        for_each_set_bit(chan, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
                ctrl4_set |= chan << LRADC_CTRL4_LRADCSELECT_OFFSET(ofs);
                ctrl4_clr |= LRADC_CTRL4_LRADCSELECT_MASK(ofs);
                ctrl1_irq |= LRADC_CTRL1_LRADC_IRQ_EN(ofs);
                mxs_lradc_reg_wrt(lradc, chan_value, LRADC_CH(ofs));
                bitmap_set(&enable, ofs, 1);
                ofs++;
        }

        mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
                                        LRADC_DELAY_KICK, LRADC_DELAY(0));
        mxs_lradc_reg_clear(lradc, ctrl4_clr, LRADC_CTRL4);
        mxs_lradc_reg_set(lradc, ctrl4_set, LRADC_CTRL4);
        mxs_lradc_reg_set(lradc, ctrl1_irq, LRADC_CTRL1);
        mxs_lradc_reg_set(lradc, enable << LRADC_DELAY_TRIGGER_LRADCS_OFFSET,
                                        LRADC_DELAY(0));

        return 0;

err_mem:
        mutex_unlock(&lradc->lock);
        return ret;
}

static int mxs_lradc_buffer_postdisable(struct iio_dev *iio)
{
        struct mxs_lradc *lradc = iio_priv(iio);

        mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
                                        LRADC_DELAY_KICK, LRADC_DELAY(0));

        mxs_lradc_reg_clear(lradc, lradc->buffer_vchans, LRADC_CTRL0);
        if (lradc->soc == IMX28_LRADC)
                mxs_lradc_reg_clear(lradc,
                        lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
                        LRADC_CTRL1);

        kfree(lradc->buffer);
        mutex_unlock(&lradc->lock);

        return 0;
}

static bool mxs_lradc_validate_scan_mask(struct iio_dev *iio,
                                        const unsigned long *mask)
{
        struct mxs_lradc *lradc = iio_priv(iio);
        const int map_chans = bitmap_weight(mask, LRADC_MAX_TOTAL_CHANS);
        int rsvd_chans = 0;
        unsigned long rsvd_mask = 0;

        if (lradc->use_touchbutton)
                rsvd_mask |= CHAN_MASK_TOUCHBUTTON;
        if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_4WIRE)
                rsvd_mask |= CHAN_MASK_TOUCHSCREEN_4WIRE;
        if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_5WIRE)
                rsvd_mask |= CHAN_MASK_TOUCHSCREEN_5WIRE;

        if (lradc->use_touchbutton)
                rsvd_chans++;
        if (lradc->use_touchscreen)
                rsvd_chans += 2;

        /* Test for attempts to map channels with special mode of operation. */
        if (bitmap_intersects(mask, &rsvd_mask, LRADC_MAX_TOTAL_CHANS))
                return false;

        /* Test for attempts to map more channels then available slots. */
        if (map_chans + rsvd_chans > LRADC_MAX_MAPPED_CHANS)
                return false;

        return true;
}

static const struct iio_buffer_setup_ops mxs_lradc_buffer_ops = {
        .preenable = &mxs_lradc_buffer_preenable,
        .postenable = &iio_triggered_buffer_postenable,
        .predisable = &iio_triggered_buffer_predisable,
        .postdisable = &mxs_lradc_buffer_postdisable,
        .validate_scan_mask = &mxs_lradc_validate_scan_mask,
};

/*
 * Driver initialization
 */

#define MXS_ADC_CHAN(idx, chan_type) {                          \
        .type = (chan_type),                                    \
        .indexed = 1,                                           \
        .scan_index = (idx),                                    \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
                              BIT(IIO_CHAN_INFO_SCALE),         \
        .channel = (idx),                                       \
        .address = (idx),                                       \
        .scan_type = {                                          \
                .sign = 'u',                                    \
                .realbits = LRADC_RESOLUTION,                   \
                .storagebits = 32,                              \
        },                                                      \
}

static const struct iio_chan_spec mxs_lradc_chan_spec[] = {
        MXS_ADC_CHAN(0, IIO_VOLTAGE),
        MXS_ADC_CHAN(1, IIO_VOLTAGE),
        MXS_ADC_CHAN(2, IIO_VOLTAGE),
        MXS_ADC_CHAN(3, IIO_VOLTAGE),
        MXS_ADC_CHAN(4, IIO_VOLTAGE),
        MXS_ADC_CHAN(5, IIO_VOLTAGE),
        MXS_ADC_CHAN(6, IIO_VOLTAGE),
        MXS_ADC_CHAN(7, IIO_VOLTAGE),   /* VBATT */
        /* Combined Temperature sensors */
        {
                .type = IIO_TEMP,
                .indexed = 1,
                .scan_index = 8,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_OFFSET) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .channel = 8,
                .scan_type = {.sign = 'u', .realbits = 18, .storagebits = 32,},
        },
        /* Hidden channel to keep indexes */
        {
                .type = IIO_TEMP,
                .indexed = 1,
                .scan_index = -1,
                .channel = 9,
        },
        MXS_ADC_CHAN(10, IIO_VOLTAGE),  /* VDDIO */
        MXS_ADC_CHAN(11, IIO_VOLTAGE),  /* VTH */
        MXS_ADC_CHAN(12, IIO_VOLTAGE),  /* VDDA */
        MXS_ADC_CHAN(13, IIO_VOLTAGE),  /* VDDD */
        MXS_ADC_CHAN(14, IIO_VOLTAGE),  /* VBG */
        MXS_ADC_CHAN(15, IIO_VOLTAGE),  /* VDD5V */
};

static int mxs_lradc_hw_init(struct mxs_lradc *lradc)
{
        /* The ADC always uses DELAY CHANNEL 0. */
        const uint32_t adc_cfg =
                (1 << (LRADC_DELAY_TRIGGER_DELAYS_OFFSET + 0)) |
                (LRADC_DELAY_TIMER_PER << LRADC_DELAY_DELAY_OFFSET);

        int ret = stmp_reset_block(lradc->base);

        if (ret)
                return ret;

        /* Configure DELAY CHANNEL 0 for generic ADC sampling. */
        mxs_lradc_reg_wrt(lradc, adc_cfg, LRADC_DELAY(0));

        /* Disable remaining DELAY CHANNELs */
        mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(1));
        mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(2));
        mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(3));

        /* Configure the touchscreen type */
        if (lradc->soc == IMX28_LRADC) {
                mxs_lradc_reg_clear(lradc, LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
                                                        LRADC_CTRL0);

        if (lradc->use_touchscreen == MXS_LRADC_TOUCHSCREEN_5WIRE)
                mxs_lradc_reg_set(lradc, LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
                                LRADC_CTRL0);
        }

        /* Start internal temperature sensing. */
        mxs_lradc_reg_wrt(lradc, 0, LRADC_CTRL2);

        return 0;
}

static void mxs_lradc_hw_stop(struct mxs_lradc *lradc)
{
        int i;

        mxs_lradc_reg_clear(lradc, mxs_lradc_irq_en_mask(lradc), LRADC_CTRL1);

        for (i = 0; i < LRADC_MAX_DELAY_CHANS; i++)
                mxs_lradc_reg_wrt(lradc, 0, LRADC_DELAY(i));
}

static const struct of_device_id mxs_lradc_dt_ids[] = {
        { .compatible = "fsl,imx23-lradc", .data = (void *)IMX23_LRADC, },
        { .compatible = "fsl,imx28-lradc", .data = (void *)IMX28_LRADC, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);

static int mxs_lradc_probe_touchscreen(struct mxs_lradc *lradc,
                                                struct device_node *lradc_node)
{
        int ret;
        u32 ts_wires = 0, adapt;

        ret = of_property_read_u32(lradc_node, "fsl,lradc-touchscreen-wires",
                                &ts_wires);
        if (ret)
                return -ENODEV; /* touchscreen feature disabled */

        switch (ts_wires) {
        case 4:
                lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_4WIRE;
                break;
        case 5:
                if (lradc->soc == IMX28_LRADC) {
                        lradc->use_touchscreen = MXS_LRADC_TOUCHSCREEN_5WIRE;
                        break;
                }
                /* fall through an error message for i.MX23 */
        default:
                dev_err(lradc->dev,
                        "Unsupported number of touchscreen wires (%d)\n",
                        ts_wires);
                return -EINVAL;
        }

        if (of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt)) {
                lradc->over_sample_cnt = 4;
        } else {
                if (adapt < 1 || adapt > 32) {
                        dev_err(lradc->dev, "Invalid sample count (%u)\n",
                                adapt);
                        return -EINVAL;
                }
                lradc->over_sample_cnt = adapt;
        }

        if (of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt)) {
                lradc->over_sample_delay = 2;
        } else {
                if (adapt < 2 || adapt > LRADC_DELAY_DELAY_MASK + 1) {
                        dev_err(lradc->dev, "Invalid sample delay (%u)\n",
                                adapt);
                        return -EINVAL;
                }
                lradc->over_sample_delay = adapt;
        }

        if (of_property_read_u32(lradc_node, "fsl,settling", &adapt)) {
                lradc->settling_delay = 10;
        } else {
                if (adapt < 1 || adapt > LRADC_DELAY_DELAY_MASK) {
                        dev_err(lradc->dev, "Invalid settling delay (%u)\n",
                                adapt);
                        return -EINVAL;
                }
                lradc->settling_delay = adapt;
        }

        return 0;
}

static int mxs_lradc_probe(struct platform_device *pdev)
{
        const struct of_device_id *of_id =
                of_match_device(mxs_lradc_dt_ids, &pdev->dev);
        const struct mxs_lradc_of_config *of_cfg =
                &mxs_lradc_of_config[(enum mxs_lradc_id)of_id->data];
        struct device *dev = &pdev->dev;
        struct device_node *node = dev->of_node;
        struct mxs_lradc *lradc;
        struct iio_dev *iio;
        struct resource *iores;
        int ret = 0, touch_ret;
        int i, s;
        uint64_t scale_uv;

        /* Allocate the IIO device. */
        iio = devm_iio_device_alloc(dev, sizeof(*lradc));
        if (!iio) {
                dev_err(dev, "Failed to allocate IIO device\n");
                return -ENOMEM;
        }

        lradc = iio_priv(iio);
        lradc->soc = (enum mxs_lradc_id)of_id->data;

        /* Grab the memory area */
        iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        lradc->dev = &pdev->dev;
        lradc->base = devm_ioremap_resource(dev, iores);
        if (IS_ERR(lradc->base))
                return PTR_ERR(lradc->base);

        lradc->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(lradc->clk)) {
                dev_err(dev, "Failed to get the delay unit clock\n");
                return PTR_ERR(lradc->clk);
        }
        ret = clk_prepare_enable(lradc->clk);
        if (ret != 0) {
                dev_err(dev, "Failed to enable the delay unit clock\n");
                return ret;
        }

        touch_ret = mxs_lradc_probe_touchscreen(lradc, node);

        if (touch_ret == 0)
                lradc->buffer_vchans = BUFFER_VCHANS_LIMITED;
        else
                lradc->buffer_vchans = BUFFER_VCHANS_ALL;

        /* Grab all IRQ sources */
        for (i = 0; i < of_cfg->irq_count; i++) {
                lradc->irq[i] = platform_get_irq(pdev, i);
                if (lradc->irq[i] < 0) {
                        ret = lradc->irq[i];
                        goto err_clk;
                }

                ret = devm_request_irq(dev, lradc->irq[i],
                                        mxs_lradc_handle_irq, 0,
                                        of_cfg->irq_name[i], iio);
                if (ret)
                        goto err_clk;
        }

        lradc->vref_mv = of_cfg->vref_mv;

        platform_set_drvdata(pdev, iio);

        init_completion(&lradc->completion);
        mutex_init(&lradc->lock);

        iio->name = pdev->name;
        iio->dev.parent = &pdev->dev;
        iio->info = &mxs_lradc_iio_info;
        iio->modes = INDIO_DIRECT_MODE;
        iio->channels = mxs_lradc_chan_spec;
        iio->num_channels = ARRAY_SIZE(mxs_lradc_chan_spec);
        iio->masklength = LRADC_MAX_TOTAL_CHANS;

        ret = iio_triggered_buffer_setup(iio, &iio_pollfunc_store_time,
                                &mxs_lradc_trigger_handler,
                                &mxs_lradc_buffer_ops);
        if (ret)
                goto err_clk;

        ret = mxs_lradc_trigger_init(iio);
        if (ret)
                goto err_trig;

        /* Populate available ADC input ranges */
        for (i = 0; i < LRADC_MAX_TOTAL_CHANS; i++) {
                for (s = 0; s < ARRAY_SIZE(lradc->scale_avail[i]); s++) {
                        /*
                         * [s=0] = optional divider by two disabled (default)
                         * [s=1] = optional divider by two enabled
                         *
                         * The scale is calculated by doing:
                         *   Vref >> (realbits - s)
                         * which multiplies by two on the second component
                         * of the array.
                         */
                        scale_uv = ((u64)lradc->vref_mv[i] * 100000000) >>
                                   (LRADC_RESOLUTION - s);
                        lradc->scale_avail[i][s].nano =
                                        do_div(scale_uv, 100000000) * 10;
                        lradc->scale_avail[i][s].integer = scale_uv;
                }
        }

        /* Configure the hardware. */
        ret = mxs_lradc_hw_init(lradc);
        if (ret)
                goto err_dev;

        /* Register the touchscreen input device. */
        if (touch_ret == 0) {
                ret = mxs_lradc_ts_register(lradc);
                if (ret)
                        goto err_ts_register;
        }

        /* Register IIO device. */
        ret = iio_device_register(iio);
        if (ret) {
                dev_err(dev, "Failed to register IIO device\n");
                goto err_ts;
        }

        return 0;

err_ts:
        mxs_lradc_ts_unregister(lradc);
err_ts_register:
        mxs_lradc_hw_stop(lradc);
err_dev:
        mxs_lradc_trigger_remove(iio);
err_trig:
        iio_triggered_buffer_cleanup(iio);
err_clk:
        clk_disable_unprepare(lradc->clk);
        return ret;
}

static int mxs_lradc_remove(struct platform_device *pdev)
{
        struct iio_dev *iio = platform_get_drvdata(pdev);
        struct mxs_lradc *lradc = iio_priv(iio);

        iio_device_unregister(iio);
        mxs_lradc_ts_unregister(lradc);
        mxs_lradc_hw_stop(lradc);
        mxs_lradc_trigger_remove(iio);
        iio_triggered_buffer_cleanup(iio);

        clk_disable_unprepare(lradc->clk);
        return 0;
}

static struct platform_driver mxs_lradc_driver = {
        .driver = {
                .name   = DRIVER_NAME,
                .of_match_table = mxs_lradc_dt_ids,
        },
        .probe  = mxs_lradc_probe,
        .remove = mxs_lradc_remove,
};

module_platform_driver(mxs_lradc_driver);

MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
MODULE_DESCRIPTION("Freescale i.MX28 LRADC driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);