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Date:   Mon, 23 Jan 2017 11:53:04 +0100
From:   Ksenija Stanojević <ksenija.stanojevic@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Lee Jones <lee.jones@...aro.org>, linux-input@...r.kernel.org,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Marek Vasut <marex@...x.de>, linux-iio@...r.kernel.org,
        Harald Geyer <harald@...ib.org>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Fabio Estevam <fabio.estevam@...escale.com>
Subject: Re: [PATCH v11 3/5] input: touchscreen: mxs-lradc: Add support for touchscreen

Hi Dmitry,

On Tue, Dec 27, 2016 at 11:39 PM, Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> Hi Ksenija,
>
> On Thu, Dec 08, 2016 at 11:27:09PM +0100, Ksenija Stanojevic wrote:
>> Add 4-wire/5-wire touchscreen controller.
>>
>> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@...il.com>
>> ---
>> Changes in v11:
>>  - use dev_get_drvdata instead dev_get_platdata
>>  - use writel instead mxs_lradc_reg_* functions
>>
>> Changes in v10:
>>  - none
>>
>> Changes in v9:
>>  - none
>>
>> Changes in v8:
>>  - rebase onto 4.9-rc1
>>
>> Changes in v7:
>>  - remove touch_ret variable in probe and use ret instead
>>  - make error check on of_property_read_u32 in probe
>>
>> Changes in v6:
>>  - update copyright
>>
>> Changes in v5:
>>  - add field void __iomem *base to struct mxs_lradc_adc
>>  - change arguments in all functions for accessing I/O memory
>>    to follow the previous change.
>>  - use devm_ioremap for mapping I/O memory
>>
>> Changes in v4:
>>  - update copyright
>>  - use platform_get_irq_byname
>>  - use irq_of_parse_and_map
>>
>> Changes in v3:
>>  - make buffer large enough for timestamps
>>  - remove unnecessary blank lines
>>
>> Changes in v2:
>>  - improve commit message
>>  - do not change spacing in Kconfig
>>  - impove formating
>>  - remove wrapper show_scale_avail
>>  - use correct syntax for comments
>>  - use devm_iio_trigger_alloc
>>  - do not allocate buffer dynamically
>>  - use iio_device_claim_*_mode helpers
>>  - add spinlock in struct mxs_lradc_ts to enable locking in interrupt handler
>>  - only grab irqs that are relevant to adc
>>  - remove blank line at the end of the file
>>  - change licence to GPL
>>  - add copyright
>>
>>  drivers/input/touchscreen/Kconfig        |  10 +
>>  drivers/input/touchscreen/Makefile       |   1 +
>>  drivers/input/touchscreen/mxs-lradc-ts.c | 739 +++++++++++++++++++++++++++++++
>>  3 files changed, 750 insertions(+)
>>  create mode 100644 drivers/input/touchscreen/mxs-lradc-ts.c
>>
>> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
>> index efca013..8ff915e 100644
>> --- a/drivers/input/touchscreen/Kconfig
>> +++ b/drivers/input/touchscreen/Kconfig
>> @@ -841,6 +841,16 @@ config TOUCHSCREEN_USB_COMPOSITE
>>         To compile this driver as a module, choose M here: the
>>         module will be called usbtouchscreen.
>>
>> +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_MX25
>>       tristate "Freescale i.MX25 touchscreen input driver"
>>       depends on MFD_MX25_TSADC
>> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
>> index 81b8645..97e1bb7 100644
>> --- a/drivers/input/touchscreen/Makefile
>> +++ b/drivers/input/touchscreen/Makefile
>> @@ -46,6 +46,7 @@ obj-$(CONFIG_TOUCHSCREEN_INTEL_MID) += intel-mid-touch.o
>>  obj-$(CONFIG_TOUCHSCREEN_IPROC)              += bcm_iproc_tsc.o
>>  obj-$(CONFIG_TOUCHSCREEN_LPC32XX)    += lpc32xx_ts.o
>>  obj-$(CONFIG_TOUCHSCREEN_MAX11801)   += max11801_ts.o
>> +obj-$(CONFIG_TOUCHSCREEN_MXS_LRADC)     += mxs-lradc-ts.o
>>  obj-$(CONFIG_TOUCHSCREEN_MX25)               += fsl-imx25-tcq.o
>>  obj-$(CONFIG_TOUCHSCREEN_MC13783)    += mc13783_ts.o
>>  obj-$(CONFIG_TOUCHSCREEN_MCS5000)    += mcs5000_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..a222e35
>> --- /dev/null
>> +++ b/drivers/input/touchscreen/mxs-lradc-ts.c
>> @@ -0,0 +1,739 @@
>> +/*
>> + * Freescale MXS LRADC touchscreen driver
>> + *
>> + * Copyright (c) 2012 DENX Software Engineering, GmbH.
>> + * Copyright (c) 2016 Ksenija Stanojevic <ksenija.stanojevic@...il.com>
>> + *
>> + * Authors:
>> + *  Marek Vasut <marex@...x.de>
>> + *  Ksenija Stanojevic <ksenija.stanojevic@...il.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; 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/device.h>
>> +#include <linux/err.h>
>> +#include <linux/input.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/module.h>
>> +#include <linux/mfd/core.h>
>> +#include <linux/mfd/mxs-lradc.h>
>> +#include <linux/of.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/platform_device.h>
>> +
>> +const char *mxs_lradc_ts_irq_names[] = {
>> +     "mxs-lradc-touchscreen",
>> +     "mxs-lradc-channel6",
>> +     "mxs-lradc-channel7",
>> +};
>> +
>> +/*
>> + * 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;
>> +
>> +     void __iomem            *base;
>> +     /*
>> +      * 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 int            ts_x_pos;
>> +     unsigned int            ts_y_pos;
>> +     unsigned int            ts_pressure;
>> +
>> +     /* handle touchscreen's physical behaviour */
>> +     /* samples per coordinate */
>> +     unsigned int            over_sample_cnt;
>> +     /* time clocks between samples */
>> +     unsigned int            over_sample_delay;
>> +     /* time in clocks to wait after the plates where switched */
>> +     unsigned int            settling_delay;
>> +     spinlock_t              lock;
>> +};
>> +
>> +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;
>
> I wonder if, instead of doing conditionals on every operation, you could
> attach const struct pointer to your device with needed values/masks.

Ok, I can try that.

>> +}
>> +
>> +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_ts *ts)
>> +{
>> +     return !!(readl(ts->base + LRADC_STATUS) &
>> +                                     LRADC_STATUS_TOUCH_DETECT_RAW);
>> +}
>> +
>> +static void mxs_lradc_map_ts_channel(struct mxs_lradc_ts *ts, unsigned int vch,
>> +                                  unsigned int ch)
>> +{
>> +     writel(LRADC_CTRL4_LRADCSELECT_MASK(vch),
>> +            ts->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_CTRL4_LRADCSELECT(vch, ch),
>> +            ts->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
>> +}
>> +
>> +static void mxs_lradc_setup_ts_channel(struct mxs_lradc_ts *ts, unsigned int 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."
>> +      */
>> +     writel(LRADC_CH_ACCUMULATE |
>> +            LRADC_CH_NUM_SAMPLES(ts->over_sample_cnt - 1),
>> +            ts->base + LRADC_CH(ch));
>> +
>> +     /* from the datasheet:
>> +      * "Software must clear this register in preparation for a
>> +      * multi-cycle accumulation.
>> +      */
>> +     writel(LRADC_CH_VALUE_MASK,
>> +            ts->base + LRADC_CH(ch) + STMP_OFFSET_REG_CLR);
>> +
>> +     /*
>> +      * 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."
>> +      */
>> +     writel(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),
>> +            ts->base + LRADC_DELAY(3));
>> +
>> +     writel(LRADC_CTRL1_LRADC_IRQ(ch),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +
>> +     /*
>> +      * 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.
>> +      */
>> +     writel(LRADC_DELAY_TRIGGER(0) | LRADC_DELAY_TRIGGER_DELAYS(BIT(3)) |
>> +            LRADC_DELAY_KICK | LRADC_DELAY_DELAY(ts->settling_delay),
>> +            ts->base + 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 int ch1, unsigned int 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(ts->over_sample_cnt - 1);
>> +     writel(reg, ts->base + LRADC_CH(ch1));
>> +     writel(reg, ts->base + LRADC_CH(ch2));
>> +
>> +     /* from the datasheet:
>> +      * "Software must clear this register in preparation for a
>> +      * multi-cycle accumulation.
>> +      */
>> +     writel(LRADC_CH_VALUE_MASK,
>> +            ts->base + LRADC_CH(ch1) + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_CH_VALUE_MASK,
>> +            ts->base + LRADC_CH(ch2) + STMP_OFFSET_REG_CLR);
>> +
>> +     /* prepare the delay/loop unit according to the oversampling count */
>> +     writel(LRADC_DELAY_TRIGGER(1 << ch1) | LRADC_DELAY_TRIGGER(1 << ch2) |
>> +            LRADC_DELAY_TRIGGER_DELAYS(0) |
>> +            LRADC_DELAY_LOOP(ts->over_sample_cnt - 1) |
>> +            LRADC_DELAY_DELAY(ts->over_sample_delay - 1),
>> +            ts->base + LRADC_DELAY(3));
>> +
>> +     writel(LRADC_CTRL1_LRADC_IRQ(ch2),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +
>> +     /*
>> +      * 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.
>> +      */
>> +     writel(LRADC_DELAY_TRIGGER(0) | LRADC_DELAY_TRIGGER_DELAYS(BIT(3)) |
>> +            LRADC_DELAY_KICK | LRADC_DELAY_DELAY(ts->settling_delay),
>> +            ts->base + LRADC_DELAY(2));
>> +}
>> +
>> +static unsigned int mxs_lradc_ts_read_raw_channel(struct mxs_lradc_ts *ts,
>> +                                               unsigned int channel)
>> +{
>> +     u32 reg;
>> +     unsigned int num_samples, val;
>> +
>> +     reg = readl(ts->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 int mxs_lradc_read_ts_pressure(struct mxs_lradc_ts *ts,
>> +                                     unsigned int ch1, unsigned int ch2)
>> +{
>> +     u32 reg, mask;
>> +     unsigned int pressure, m1, m2;
>> +
>> +     mask = LRADC_CTRL1_LRADC_IRQ(ch1) | LRADC_CTRL1_LRADC_IRQ(ch2);
>> +     reg = readl(ts->base + LRADC_CTRL1) & mask;
>> +
>> +     while (reg != mask) {
>> +             reg = readl(ts->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
>> +      */
>> +     writel(mxs_lradc_plate_mask(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +     writel(mxs_lradc_touch_detect_bit(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
>> +}
>> +
>> +/*
>> + * 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;
>> +
>> +     writel(mxs_lradc_plate_mask(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +     writel(mxs_lradc_drive_x_plate(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
>> +
>> +     ts->cur_plate = LRADC_SAMPLE_X;
>> +     mxs_lradc_map_ts_channel(ts, 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;
>> +
>> +     writel(mxs_lradc_plate_mask(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +     writel(mxs_lradc_drive_y_plate(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
>> +
>> +     ts->cur_plate = LRADC_SAMPLE_Y;
>> +     mxs_lradc_map_ts_channel(ts, 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;
>> +
>> +     writel(mxs_lradc_plate_mask(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +     writel(mxs_lradc_drive_pressure(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
>> +
>> +     ts->cur_plate = LRADC_SAMPLE_PRESSURE;
>> +     mxs_lradc_map_ts_channel(ts, TOUCHSCREEN_VCHANNEL1, TS_CH_YM);
>> +     mxs_lradc_map_ts_channel(ts, 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;
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ | LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
>> +}
>> +
>> +static void mxs_lradc_start_touch_event(struct mxs_lradc_ts *ts)
>> +{
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
>> +     /*
>> +      * 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)
>> +{
>> +     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
>> +      */
>> +     writel(0, ts->base + LRADC_CH(TOUCHSCREEN_VCHANNEL1));
>> +     writel(LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1) |
>> +            LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL2),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_DELAY_TRIGGER(1 << TOUCHSCREEN_VCHANNEL1) |
>> +            LRADC_DELAY_KICK | LRADC_DELAY_DELAY(10),
>> +            ts->base + 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)
>> +{
>> +     /* if it is still touched, report the sample */
>> +     if (valid && mxs_lradc_check_touch_event(ts)) {
>> +             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(ts)) {
>> +             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;
>> +     writel(0, ts->base + LRADC_DELAY(2));
>> +     writel(0, ts->base + LRADC_DELAY(3));
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ |
>> +            LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1) |
>> +            LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
>> +}
>> +
>> +/* touchscreen's state machine */
>> +static void mxs_lradc_handle_touch(struct mxs_lradc_ts *ts)
>> +{
>> +     switch (ts->cur_plate) {
>> +     case LRADC_TOUCH:
>> +             if (mxs_lradc_check_touch_event(ts))
>> +                     mxs_lradc_start_touch_event(ts);
>> +             writel(LRADC_CTRL1_TOUCH_DETECT_IRQ,
>> +                    ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +             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(ts->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);
>> +     unsigned long flags;
>> +
>> +     if (!(reg & mxs_lradc_irq_mask(lradc)))
>> +             return IRQ_NONE;
>> +
>> +     if (reg & ts_irq_mask) {
>> +             spin_lock_irqsave(&ts->lock, flags);
>> +             mxs_lradc_handle_touch(ts);
>> +             spin_unlock_irqrestore(&ts->lock, flags);
>> +             /* 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));
>> +             writel(reg & clr_irq,
>> +                    ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +     }
>> +
>> +     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_ts_stop(struct mxs_lradc_ts *ts)
>> +{
>> +     int i;
>> +     struct mxs_lradc *lradc = ts->lradc;
>> +
>> +     /* stop all interrupts from firing */
>> +     writel(LRADC_CTRL1_TOUCH_DETECT_IRQ_EN |
>> +            LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1) |
>> +            LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL2),
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +
>> +     /* Power-down touchscreen touch-detect circuitry. */
>> +     writel(mxs_lradc_plate_mask(lradc),
>> +            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +
>> +     writel(lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
>> +            ts->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
>> +
>> +     for (i = 1; i < LRADC_MAX_DELAY_CHANS; i++)
>> +             writel(0, ts->base + LRADC_DELAY(i));
>> +}
>> +
>> +static void mxs_lradc_ts_close(struct input_dev *dev)
>> +{
>> +     struct mxs_lradc_ts *ts = input_get_drvdata(dev);
>> +
>> +     mxs_lradc_ts_stop(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) {
>> +             writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
>> +                    ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
>> +
>> +             if (lradc->touchscreen_wire == MXS_LRADC_TOUCHSCREEN_5WIRE)
>> +                     writel(LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
>> +                            ts->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
>> +     }
>> +}
>> +
>> +static int mxs_lradc_ts_register(struct mxs_lradc_ts *ts)
>> +{
>> +     struct input_dev *input = ts->ts_input;
>> +     struct device *dev = ts->dev;
>> +
>> +     input = devm_input_allocate_device(dev);
>> +     if (!input)
>> +             return -ENOMEM;
>> +
>> +     input->name = "mxs-lradc-ts";
>> +     input->id.bustype = BUS_HOST;
>> +     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_drvdata(dev->parent);
>> +     struct mxs_lradc_ts *ts;
>> +     struct resource *iores;
>> +     int ret, irq, virq, i;
>> +     u32 ts_wires = 0, adapt;
>> +
>> +     ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
>> +     if (!ts)
>> +             return -ENOMEM;
>> +
>> +     platform_set_drvdata(pdev, ts);
>> +
>> +     ts->lradc = lradc;
>> +     ts->dev = dev;
>> +     spin_lock_init(&ts->lock);
>> +
>> +     iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     ts->base = devm_ioremap(dev, iores->start, resource_size(iores));
>> +     if (IS_ERR(ts->base))
>> +             return PTR_ERR(ts->base);
>> +
>> +     ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
>> +                                &ts_wires);
>> +     if (ret)
>> +             return ret;
>> +
>> +     if (of_property_read_u32(node, "fsl,ave-ctrl", &adapt)) {
>> +             ts->over_sample_cnt = 4;
>> +     } else {
>> +             if (adapt >= 1 || adapt <= 32) {
>> +                     ts->over_sample_cnt = adapt;
>> +             } else {
>> +                     dev_err(ts->dev, "Invalid sample count (%u)\n",
>> +                             adapt);
>> +                     return -EINVAL;
>> +             }
>> +     }
>> +
>> +     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) {
>> +                     ts->over_sample_delay = adapt;
>> +             } else {
>> +                     dev_err(ts->dev, "Invalid sample delay (%u)\n",
>> +                             adapt);
>> +                     return -EINVAL;
>> +             }
>> +     }
>> +
>> +     if (of_property_read_u32(node, "fsl,settling", &adapt)) {
>> +             ts->settling_delay = 10;
>> +     } else {
>> +             if (adapt >= 1 || adapt <= LRADC_DELAY_DELAY_MASK) {
>> +                     ts->settling_delay = adapt;
>> +             } else {
>> +                     dev_err(ts->dev, "Invalid settling delay (%u)\n",
>> +                             adapt);
>> +                     return -EINVAL;
>> +             }
>> +     }
>> +
>> +     ret = stmp_reset_block(ts->base);
>> +     if (ret)
>> +             return ret;
>> +
>> +     mxs_lradc_ts_hw_init(ts);
>> +
>> +     for (i = 0; i < 3; i++) {
>> +             irq = platform_get_irq_byname(pdev, mxs_lradc_ts_irq_names[i]);
>> +             if (irq < 0)
>> +                     return irq;
>> +
>> +             virq = irq_of_parse_and_map(node, irq);
>
> Why do we need this? I'd expect parent to fully prepare interrupts for
> the child to use. I.e. I'd expect I could do platform_get_irq_byname()
> and them go straight to devm_request_irq().

Well probe fails and devm_request_irq trows error -22 in that case,
so I think that use of irq_of_parse_and_map is needed.

>> +
>> +             ret = devm_request_irq(dev, virq,
>> +                                    mxs_lradc_ts_handle_irq,
>> +                                    0, mxs_lradc_ts_irq_names[i], ts);
>> +             if (ret)
>> +                     return ret;
>> +     }
>> +
>> +     ret = mxs_lradc_ts_register(ts);
>> +     if (!ret)
>> +             goto error;
>> +
>> +     return 0;
>> +
>> +error:
>> +     mxs_lradc_ts_stop(ts);
>
> Why do you want to stop only if mxs_lradc_ts_register() fails? If open()
> has been called, then close() should be called on error automatically.
> That said, shouldn't you call mxs_lradc_ts_stop() before requesting
> interrupts, just to make sure they do not start firing early (even
> though I think it should be safe if they do)?

Ok, I will do that.

Thanks,
Ksenija

> Thanks.
>
>> +
>> +     return ret;
>> +}
>> +
>> +static struct platform_driver mxs_lradc_ts_driver = {
>> +     .driver = {
>> +             .name = "mxs-lradc-ts",
>> +     },
>> +     .probe  = mxs_lradc_ts_probe,
>> +};
>> +module_platform_driver(mxs_lradc_ts_driver);
>> +
>> +MODULE_AUTHOR("Marek Vasut <marex@...x.de>");
>> +MODULE_DESCRIPTION("Freescale MXS LRADC touchscreen driver");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:mxs-lradc-ts");
>> --
>> 1.9.1
>>
>
> --
> Dmitry

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