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

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On 28/05/16 18:45, Ksenija Stanojević wrote:
> 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)
Certainly should only grab the relevant ones to touch screen use in here..
Original code probably being overly enthusiastic and we never noticed ;)
> 
> 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");
>>>
>>
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