Re: [PATCH 3/3] input: touchscreen: mxs-lradc: Add support for touchscreen

From: Ksenija StanojeviÄ
Date: Sat May 28 2016 - 13:45:48 EST

On Sun, May 1, 2016 at 6:47 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 29/04/16 12:49, Ksenija Stanojevic wrote:
>> Add mxs-lradc touchscreen driver.
>>
>> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@xxxxxxxxx>
> The only real thing this raises for me is why we are grabbing IRQs that I
> don't think this driver even cares about...
>
> Jonathan
>> ---
>> drivers/input/touchscreen/Kconfig | 14 +-
>> drivers/input/touchscreen/Makefile | 1 +
>> drivers/input/touchscreen/mxs-lradc-ts.c | 729 +++++++++++++++++++++++++++++++
>> 3 files changed, 742 insertions(+), 2 deletions(-)
>> create mode 100644 drivers/input/touchscreen/mxs-lradc-ts.c
>>
>> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
>> index 8ecdc38..d614d248 100644
>> --- a/drivers/input/touchscreen/Kconfig
>> +++ b/drivers/input/touchscreen/Kconfig
>> @@ -566,7 +566,7 @@ config TOUCHSCREEN_HP600
>> depends on SH_HP6XX && SH_ADC
>> help
>> Say Y here if you have a HP Jornada 620/660/680/690 and want to
>> - support the built-in touchscreen.
>> + support the built-in touchscreen.
>>
>> To compile this driver as a module, choose M here: the
>> module will be called hp680_ts_input.
>> @@ -685,7 +685,7 @@ config TOUCHSCREEN_UCB1400
>> This enables support for the Philips UCB1400 touchscreen interface.
>> The UCB1400 is an AC97 audio codec. The touchscreen interface
>> will be initialized only after the ALSA subsystem has been
>> - brought up and the UCB1400 detected. You therefore have to
>> + brought up and the UCB1400 detected. You therefore have to
>> configure ALSA support as well (either built-in or modular,
>> independently of whether this driver is itself built-in or
>> modular) for this driver to work.
>> @@ -842,6 +842,16 @@ config TOUCHSCREEN_MX25
>> To compile this driver as a module, choose M here: the
>> module will be called fsl-imx25-tcq.
>>
>> +config TOUCHSCREEN_MXS_LRADC
>> + tristate "Freescale i.MX23/i.MX28 LRADC touchscreen"
>> + depends on MFD_MXS_LRADC
>> + help
>> + Say Y here if you have a touchscreen connected to the low-resolution
>> + analog-to-digital converter (LRADC) on an i.MX23 or i.MX28 processor.
>> +
>> + To compile this driver as a module, choose M here: the module will be
>> + called mxs-lradc-ts.
>> +
>> config TOUCHSCREEN_MC13783
>> tristate "Freescale MC13783 touchscreen input driver"
>> depends on MFD_MC13XXX
>> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
>> index f42975e..513a6ff 100644
>> --- a/drivers/input/touchscreen/Makefile
>> +++ b/drivers/input/touchscreen/Makefile
>> @@ -54,6 +54,7 @@ obj-$(CONFIG_TOUCHSCREEN_MIGOR) += migor_ts.o
>> obj-$(CONFIG_TOUCHSCREEN_MMS114) += mms114.o
>> obj-$(CONFIG_TOUCHSCREEN_MTOUCH) += mtouch.o
>> obj-$(CONFIG_TOUCHSCREEN_MK712) += mk712.o
>> +obj-$(CONFIG_TOUCHSCREEN_MXS_LRADC) += mxs-lradc-ts.o
>> obj-$(CONFIG_TOUCHSCREEN_HP600) += hp680_ts_input.o
>> obj-$(CONFIG_TOUCHSCREEN_HP7XX) += jornada720_ts.o
>> obj-$(CONFIG_TOUCHSCREEN_IPAQ_MICRO) += ipaq-micro-ts.o
>> diff --git a/drivers/input/touchscreen/mxs-lradc-ts.c b/drivers/input/touchscreen/mxs-lradc-ts.c
>> new file mode 100644
>> index 0000000..27abb8e
>> --- /dev/null
>> +++ b/drivers/input/touchscreen/mxs-lradc-ts.c
>> @@ -0,0 +1,729 @@
>> +/*
>> + * Freescale MXS LRADC driver
>> + *
>> + * Copyright (c) 2012 DENX Software Engineering, GmbH.
>> + * Marek Vasut <marex@xxxxxxx>
>> + *
>> + * 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/module.h>
>> +#include <linux/mfd/mxs-lradc.h>
>> +#include <linux/platform_device.h>
>> +
>> +/*
>> + * Touchscreen handling
>> + */
>> +enum mxs_lradc_ts_plate {
>> + LRADC_TOUCH = 0,
>> + LRADC_SAMPLE_X,
>> + LRADC_SAMPLE_Y,
>> + LRADC_SAMPLE_PRESSURE,
>> + LRADC_SAMPLE_VALID,
>> +};
>> +
>> +struct mxs_lradc_ts {
>> + struct mxs_lradc *lradc;
>> + struct device *dev;
>> + /*
>> + * 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
>> +
>> + struct input_dev *ts_input;
>> +
>> + enum mxs_lradc_ts_plate cur_plate; /* state machine */
>> + 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;
>> +};
>> +
>> +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_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_ts_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_ts *ts, unsigned ch)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + /*
>> + * 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(ts->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(ts->over_sample_cnt - 1) |
>> + LRADC_DELAY_DELAY(ts->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(ts->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_ts *ts, unsigned ch1,
>> + unsigned ch2)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> + 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(ts->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(ts->over_sample_cnt - 1) |
>> + LRADC_DELAY_DELAY(ts->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(ts->settling_delay), LRADC_DELAY(2));
>> +}
>> +
>> +static unsigned mxs_lradc_ts_read_raw_channel(struct mxs_lradc_ts *ts,
>> + unsigned channel)
>> +{
>> + u32 reg;
>> + unsigned num_samples, val;
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + reg = readl(lradc->base + LRADC_CH(channel));
>> + if (reg & LRADC_CH_ACCUMULATE)
>> + num_samples = ts->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_ts *ts,
>> + unsigned ch1, unsigned ch2)
>> +{
>> + u32 reg, mask;
>> + unsigned pressure, m1, m2;
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + 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(ts->dev, "One channel is still busy: %X\n", reg);
>> + }
>> +
>> + m1 = mxs_lradc_ts_read_raw_channel(ts, ch1);
>> + m2 = mxs_lradc_ts_read_raw_channel(ts, ch2);
>> +
>> + if (m2 == 0) {
>> + dev_warn(ts->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(ts->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_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->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_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->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);
>> +
>> + ts->cur_plate = LRADC_SAMPLE_X;
>> + mxs_lradc_map_ts_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_YP);
>> + mxs_lradc_setup_ts_channel(ts, 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_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->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);
>> +
>> + ts->cur_plate = LRADC_SAMPLE_Y;
>> + mxs_lradc_map_ts_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_XM);
>> + mxs_lradc_setup_ts_channel(ts, 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_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->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);
>> +
>> + ts->cur_plate = LRADC_SAMPLE_PRESSURE;
>> + mxs_lradc_map_ts_channel(lradc, TOUCHSCREEN_VCHANNEL1, TS_CH_YM);
>> + mxs_lradc_map_ts_channel(lradc, TOUCHSCREEN_VCHANNEL2, TS_CH_XP);
>> + mxs_lradc_setup_ts_pressure(ts, TOUCHSCREEN_VCHANNEL2,
>> + TOUCHSCREEN_VCHANNEL1);
>> +}
>> +
>> +static void mxs_lradc_enable_touch_detection(struct mxs_lradc_ts *ts)
>> +{
>> + mxs_lradc_setup_touch_detection(ts);
>> +
>> + ts->cur_plate = LRADC_TOUCH;
>> + mxs_lradc_reg_clear(ts->lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ |
>> + LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
>> + mxs_lradc_reg_set(ts->lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> + LRADC_CTRL1);
>> +}
>> +
>> +static void mxs_lradc_start_touch_event(struct mxs_lradc_ts *ts)
>> +{
>> + mxs_lradc_reg_clear(ts->lradc,
>> + LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> + LRADC_CTRL1);
>> + mxs_lradc_reg_set(ts->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(ts);
>> +}
>> +
>> +static void mxs_lradc_report_ts_event(struct mxs_lradc_ts *ts)
>> +{
>> + input_report_abs(ts->ts_input, ABS_X, ts->ts_x_pos);
>> + input_report_abs(ts->ts_input, ABS_Y, ts->ts_y_pos);
>> + input_report_abs(ts->ts_input, ABS_PRESSURE, ts->ts_pressure);
>> + input_report_key(ts->ts_input, BTN_TOUCH, 1);
>> + input_sync(ts->ts_input);
>> +}
>> +
>> +static void mxs_lradc_complete_touch_event(struct mxs_lradc_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + mxs_lradc_setup_touch_detection(ts);
>> + ts->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_ts *ts, bool valid)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + /* if it is still touched, report the sample */
>> + if (valid && mxs_lradc_check_touch_event(lradc)) {
>> + ts->ts_valid = true;
>> + mxs_lradc_report_ts_event(ts);
>> + }
>> +
>> + /* if it is even still touched, continue with the next measurement */
>> + if (mxs_lradc_check_touch_event(lradc)) {
>> + mxs_lradc_prepare_y_pos(ts);
>> + return;
>> + }
>> +
>> + if (ts->ts_valid) {
>> + /* signal the release */
>> + ts->ts_valid = false;
>> + input_report_key(ts->ts_input, BTN_TOUCH, 0);
>> + input_sync(ts->ts_input);
>> + }
>> +
>> + /* if it is released, wait for the next touch via IRQ */
>> + ts->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_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + switch (ts->cur_plate) {
>> + case LRADC_TOUCH:
>> + if (mxs_lradc_check_touch_event(lradc))
>> + mxs_lradc_start_touch_event(ts);
>> + mxs_lradc_reg_clear(lradc, LRADC_CTRL1_TOUCH_DETECT_IRQ,
>> + LRADC_CTRL1);
>> + return;
>> +
>> + case LRADC_SAMPLE_Y:
>> + ts->ts_y_pos =
>> + mxs_lradc_ts_read_raw_channel(ts, TOUCHSCREEN_VCHANNEL1);
>> + mxs_lradc_prepare_x_pos(ts);
>> + return;
>> +
>> + case LRADC_SAMPLE_X:
>> + ts->ts_x_pos =
>> + mxs_lradc_ts_read_raw_channel(ts, TOUCHSCREEN_VCHANNEL1);
>> + mxs_lradc_prepare_pressure(ts);
>> + return;
>> +
>> + case LRADC_SAMPLE_PRESSURE:
>> + ts->ts_pressure =
>> + mxs_lradc_read_ts_pressure(ts,
>> + TOUCHSCREEN_VCHANNEL2,
>> + TOUCHSCREEN_VCHANNEL1);
>> + mxs_lradc_complete_touch_event(ts);
>> + return;
>> +
>> + case LRADC_SAMPLE_VALID:
>> + mxs_lradc_finish_touch_event(ts, 1);
>> + break;
>> + }
>> +}
>> +
>> +/*
>> + * IRQ Handling
>> + */
>> +static irqreturn_t mxs_lradc_ts_handle_irq(int irq, void *data)
>> +{
>> + struct mxs_lradc_ts *ts = data;
>> + struct mxs_lradc *lradc = ts->lradc;
>> + unsigned long reg = readl(lradc->base + LRADC_CTRL1);
>> + u32 clr_irq = mxs_lradc_irq_mask(lradc);
>> + const u32 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(ts);
>> +
>> + /* 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));
>> + mxs_lradc_reg_clear(lradc, reg & clr_irq, LRADC_CTRL1);
>> + }
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int mxs_lradc_ts_open(struct input_dev *dev)
>> +{
>> + struct mxs_lradc_ts *ts = input_get_drvdata(dev);
>> +
>> + /* Enable the touch-detect circuitry. */
>> + mxs_lradc_enable_touch_detection(ts);
>> +
>> + return 0;
>> +}
>> +
>> +static void mxs_lradc_disable_ts(struct mxs_lradc_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->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_ts *ts = input_get_drvdata(dev);
>> +
>> + mxs_lradc_disable_ts(ts);
>> +}
>> +
>> +static void mxs_lradc_ts_hw_init(struct mxs_lradc_ts *ts)
>> +{
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + /* 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);
>> + }
>> +}
>> +
>> +static void mxs_lradc_ts_hw_stop(struct mxs_lradc_ts *ts)
>> +{
>> + int i;
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + mxs_lradc_reg_clear(lradc,
>> + lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
>> + LRADC_CTRL1);
>> +
>> + for (i = 1; i < LRADC_MAX_DELAY_CHANS; i++)
>> + mxs_lradc_reg_wrt(ts->lradc, 0, LRADC_DELAY(i));
>> +}
>> +
>> +static int mxs_lradc_ts_register(struct mxs_lradc_ts *ts)
>> +{
>> + struct input_dev *input = ts->ts_input;
>> + struct device *dev = ts->dev;
>> + struct mxs_lradc *lradc = ts->lradc;
>> +
>> + if (!lradc->use_touchscreen)
>> + return 0;
>> +
>> + input->name = DRIVER_NAME_TS;
>> + 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);
>> + __set_bit(INPUT_PROP_DIRECT, input->propbit);
>> + 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);
>> +
>> + ts->ts_input = input;
>> + input_set_drvdata(input, ts);
>> +
>> + return input_register_device(input);
>> +}
>> +
>> +static int mxs_lradc_ts_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct device_node *node = dev->parent->of_node;
>> + struct mxs_lradc *lradc = dev_get_platdata(dev);
>> + struct mxs_lradc_ts *ts;
>> + struct input_dev *input;
>> + int touch_ret, ret, i;
>> + u32 ts_wires = 0, adapt;
>> +
>> + ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
>> + input = devm_input_allocate_device(dev);
>> + if (!ts || !input)
>> + return -ENOMEM;
>> +
>> + ts->lradc = lradc;
>> + ts->dev = dev;
>> + ts->ts_input = input;
>> + platform_set_drvdata(pdev, ts);
>> + input_set_drvdata(input, ts);
>> +
>> + touch_ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
>> + &ts_wires);
>> +
>> + if (of_property_read_u32(node, "fsl,ave-ctrl", &adapt)) {
>> + ts->over_sample_cnt = 4;
>> + } else {
>> + if (adapt < 1 || adapt > 32) {
>> + dev_err(ts->dev, "Invalid sample count (%u)\n",
>> + adapt);
>> + touch_ret = -EINVAL;
>> + } else {
>> + ts->over_sample_cnt = adapt;
>> + }
>> + }
>> +
>> + if (of_property_read_u32(node, "fsl,ave-delay", &adapt)) {
>> + ts->over_sample_delay = 2;
>> + } else {
>> + if (adapt < 2 || adapt > LRADC_DELAY_DELAY_MASK + 1) {
>> + dev_err(ts->dev, "Invalid sample delay (%u)\n",
>> + adapt);
>> + touch_ret = -EINVAL;
>> + } else {
>> + ts->over_sample_delay = adapt;
>> + }
>> + }
>> +
>> + if (of_property_read_u32(node, "fsl,settling", &adapt)) {
>> + ts->settling_delay = 10;
>> + } else {
>> + if (adapt < 1 || adapt > LRADC_DELAY_DELAY_MASK) {
>> + dev_err(ts->dev, "Invalid settling delay (%u)\n",
>> + adapt);
>> + touch_ret = -EINVAL;
>> + } else {
>> + ts->settling_delay = adapt;
>> + }
>> + }
>> +
>> + mxs_lradc_ts_hw_init(ts);
>> + for (i = 0; i < lradc->irq_count; i++) {
>> + ret = devm_request_irq(dev, lradc->irq[i],
>> + mxs_lradc_ts_handle_irq,
>> + IRQF_SHARED, lradc->irq_name[i], ts);
> As with the adc driver, are we actually using all of these? I'd prefer we
> only grab the ones that are actually relevant.

Only irq lines relevant for touchscreen are:
mxs-lradc-touchscreen, mxs-lradc-channel6 and mxs-lradc-channel7
But not all interrupts are beiing used even when I enabled all remaining
channels (not used by touchscreen) for bufferd capture via
echo 1 >/sys/bus/iio/devices/iio\:device0/scan_elements/in_voltagexx_en

So I don't know if it's supposed to work like this...
(It works the same on the original code)

root@cfa100xx:~# cat /proc/interrupts
CPU0
16: 13108 - 48 Edge MXS Timer Tick
17: 4240 - 82 Edge mxs-dma
25: 6 - 96 Edge 80010000.ssp
196: 0 - 68 Edge mxs-dma
210: 13 - 10 Edge mxs-lradc-touchscreen
211: 0 - 14 Edge mxs-lradc-thresh0
212: 0 - 15 Edge mxs-lradc-thresh1
213: 10 - 16 Edge mxs-lradc-channel0
214: 10 - 17 Edge mxs-lradc-channel1
215: 0 - 18 Edge mxs-lradc-channel2
216: 0 - 19 Edge mxs-lradc-channel3
217: 0 - 20 Edge mxs-lradc-channel4
218: 0 - 21 Edge mxs-lradc-channel5
219: 0 - 22 Edge mxs-lradc-channel6
220: 412 - 23 Edge mxs-lradc-channel7
221: 0 - 24 Edge mxs-lradc-button0
222: 0 - 25 Edge mxs-lradc-button1
223: 0 - 29 Edge RTC alarm
224: 0 - 111 Edge 80058000.i2c
228: 174 - 47 Edge uart-pl011
229: 439 - 93 Edge 80080000.usb
230: 0 - 92 Edge 80090000.usb
231: 3610 - 101 Edge 800f0000.ethernet
232: 10 80050000.lradc-dev0 Edge
Err: 0

>> + if (ret)
>> + return ret;
>> + }
>> +
>> + if (!touch_ret) {
>> + ret = mxs_lradc_ts_register(ts);
>> + if (!ret)
>> + goto err_ts_register;
>> + }
>> +
>> + return 0;
>> +
>> +err_ts_register:
>> + mxs_lradc_ts_hw_stop(ts);
>> + return ret;
>> +}
>> +
>> +static int mxs_lradc_ts_remove(struct platform_device *pdev)
>> +{
>> + struct mxs_lradc_ts *ts = platform_get_drvdata(pdev);
>> +
>> + mxs_lradc_ts_hw_stop(ts);
>> +
>> + return 0;
>> +}
>> +
>> +static struct platform_driver mxs_lradc_ts_driver = {
>> + .driver = {
>> + .name = DRIVER_NAME_TS,
>> + },
>> + .probe = mxs_lradc_ts_probe,
>> + .remove = mxs_lradc_ts_remove,
>> +};
>> +module_platform_driver(mxs_lradc_ts_driver);
>> +
>> +MODULE_LICENSE("GPL v2");
>>
>