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

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On Sat, Apr 30, 2016 at 1:36 AM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> Hi Ksenija,
>
> On Fri, Apr 29, 2016 at 01:49:11PM +0200, Ksenija Stanojevic wrote:
>> Add mxs-lradc touchscreen driver.
>>
>> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@xxxxxxxxx>
>> ---
>>  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
>
> Why do we have the tab in the middle of the text?
>
>>         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)) {
>
> Why do we have this flag instead of not creating the platform device by
> MFD parent when touchscreen is not in use?
>
>> +             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;
>
> Not needed for devm-managed input devices.
>
>> +     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);
>
> I'd expect input allocation be done in mxs_lradc_ts_register().
>
>> +     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;
>
> Why are we not aborting here?
>
>> +             } 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,
>
> Hmm, if you have several interrupts handled by the same interrupt
> handler you'd need some locking there.

same interrupt handler can run concurrently only on multi cores, so
why do we need locking?

>
>> +                                    IRQF_SHARED, lradc->irq_name[i], ts);
>> +             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;
>
> Would prefer calling this variable "error".
>
>> +}
>> +
>> +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);
>
> I wonder if mxs_lradc_ts_hw_stop() can be combined with
> mxs_lradc_disable_ts() which is called automatically if input device is
> opened? This way we'd be able to get rid of mxs_lradc_ts_remove().
>
>> +
>> +     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");
>
> "GPL" since you are not limiting to v2 only.
>
> Thanks.
>
> --
> Dmitry
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