Message-Id: <fed1bdf55d99ab04f19109841644fa3727d818e9.1474108510.git.ksenija.stanojevic@gmail.com>
Date:   Sat, 17 Sep 2016 12:48:57 +0200
From:   Ksenija Stanojevic <ksenija.stanojevic@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     lee.jones@...aro.org, dmitry.torokhov@...il.com,
        linux-input@...r.kernel.org, jic23@...nel.org, knaack.h@....de,
        lars@...afoo.de, pmeerw@...erw.net, marex@...x.de,
        linux-iio@...r.kernel.org, harald@...ib.org,
        stefan.wahren@...e.com, fabio.estevam@...escale.com,
        Ksenija Stanojevic <ksenija.stanojevic@...il.com>
Subject: [PATCH v6 3/4] input: touchscreen: mxs-lradc: Add support for touchscreen

Add 4-wire/5-wire touchscreen controller.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@...il.com>
---
Changes in v6:
 - update copyright

Changes in v5:
 - add field void __iomem *base to struct mxs_lradc_ts
 - 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:
 - add MODULE_*(ALIAS, AUTHOR, DESCRIPTION)

Changes in v2:
 - do not change spacing in Kconfig
 - remove dev.parent
 - rename err_ts_register to error
 - combine functions hw_stop and disable_ts so that mxs_lradc_ts_remove
   could be deleted.
 - add spinlock in struct mxs_lradc_ts to enable locking in interrupt handler.
 - only grab irqs that are relevant to touchscreen
 - use direct return instead assigning error to touch_ret in probe function.
 - change licence to GPL
 - add copyright

 drivers/input/touchscreen/Kconfig        |  10 +
 drivers/input/touchscreen/Makefile       |   1 +
 drivers/input/touchscreen/mxs-lradc-ts.c | 743 +++++++++++++++++++++++++++++++
 3 files changed, 754 insertions(+)
 create mode 100644 drivers/input/touchscreen/mxs-lradc-ts.c

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 66c6264..a34661d 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -305,6 +305,16 @@ config TOUCHSCREEN_EGALAX_SERIAL
 	  To compile this driver as a module, choose M here: the
 	  module will be called egalax_ts_serial.
 
+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_FT6236
 	tristate "FT6236 I2C touchscreen"
 	depends on I2C
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 968ff12..6319b5c 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -52,6 +52,7 @@ 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..fcde798
--- /dev/null
+++ b/drivers/input/touchscreen/mxs-lradc-ts.c
@@ -0,0 +1,743 @@
+/*
+ * 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;
+}
+
+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)
+{
+	mxs_lradc_reg_clear(ts->base, LRADC_CTRL4_LRADCSELECT_MASK(vch),
+			    LRADC_CTRL4);
+	mxs_lradc_reg_set(ts->base, LRADC_CTRL4_LRADCSELECT(vch, ch),
+			  LRADC_CTRL4);
+}
+
+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."
+	 */
+	mxs_lradc_reg_wrt(ts->base, 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(ts->base, 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(ts->base, 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(ts->base, 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(ts->base,
+		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 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);
+	mxs_lradc_reg_wrt(ts->base, reg, LRADC_CH(ch1));
+	mxs_lradc_reg_wrt(ts->base, reg, LRADC_CH(ch2));
+
+	/* from the datasheet:
+	 * "Software must clear this register in preparation for a
+	 * multi-cycle accumulation.
+	 */
+	mxs_lradc_reg_clear(ts->base, LRADC_CH_VALUE_MASK, LRADC_CH(ch1));
+	mxs_lradc_reg_clear(ts->base, LRADC_CH_VALUE_MASK, LRADC_CH(ch2));
+
+	/* prepare the delay/loop unit according to the oversampling count */
+	mxs_lradc_reg_wrt(ts->base,
+		    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(ts->base, 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(ts->base,
+		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 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
+	 */
+	mxs_lradc_reg_clear(ts->base, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(ts->base, 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(ts->base, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(ts->base, mxs_lradc_drive_x_plate(lradc),
+			  LRADC_CTRL0);
+
+	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;
+
+	mxs_lradc_reg_clear(ts->base, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(ts->base, mxs_lradc_drive_y_plate(lradc),
+			  LRADC_CTRL0);
+
+	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;
+
+	mxs_lradc_reg_clear(ts->base, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+	mxs_lradc_reg_set(ts->base, mxs_lradc_drive_pressure(lradc),
+			  LRADC_CTRL0);
+
+	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;
+	mxs_lradc_reg_clear(ts->base, LRADC_CTRL1_TOUCH_DETECT_IRQ |
+			    LRADC_CTRL1_TOUCH_DETECT_IRQ_EN, LRADC_CTRL1);
+	mxs_lradc_reg_set(ts->base, 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->base,
+			    LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
+			    LRADC_CTRL1);
+	mxs_lradc_reg_set(ts->base,
+			  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)
+{
+	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(ts->base, 0, LRADC_CH(TOUCHSCREEN_VCHANNEL1));
+	mxs_lradc_reg_clear(ts->base,
+			    LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1) |
+			    LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL2),
+			    LRADC_CTRL1);
+	mxs_lradc_reg_wrt(ts->base,
+		    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)
+{
+	/* 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;
+	mxs_lradc_reg_wrt(ts->base, 0, LRADC_DELAY(2));
+	mxs_lradc_reg_wrt(ts->base, 0, LRADC_DELAY(3));
+	mxs_lradc_reg_clear(ts->base,
+			    LRADC_CTRL1_TOUCH_DETECT_IRQ |
+			    LRADC_CTRL1_LRADC_IRQ_EN(TOUCHSCREEN_VCHANNEL1) |
+			    LRADC_CTRL1_LRADC_IRQ(TOUCHSCREEN_VCHANNEL1),
+			    LRADC_CTRL1);
+	mxs_lradc_reg_set(ts->base, LRADC_CTRL1_TOUCH_DETECT_IRQ_EN,
+			  LRADC_CTRL1);
+}
+
+/* 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);
+		mxs_lradc_reg_clear(ts->base, 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(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));
+		mxs_lradc_reg_clear(ts->base, 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_ts_stop(struct mxs_lradc_ts *ts)
+{
+	int i;
+	struct mxs_lradc *lradc = ts->lradc;
+
+	/* stop all interrupts from firing */
+	mxs_lradc_reg_clear(ts->base, 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(ts->base, mxs_lradc_plate_mask(lradc), LRADC_CTRL0);
+
+	mxs_lradc_reg_clear(ts->base,
+			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->base, 0, 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) {
+		mxs_lradc_reg_clear(ts->base,
+				    LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
+				    LRADC_CTRL0);
+
+		if (lradc->touchscreen_wire == MXS_LRADC_TOUCHSCREEN_5WIRE)
+			mxs_lradc_reg_set(ts->base,
+					  LRADC_CTRL0_MX28_TOUCH_SCREEN_TYPE,
+					  LRADC_CTRL0);
+	}
+}
+
+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_platdata(dev);
+	struct mxs_lradc_ts *ts;
+	struct resource *iores;
+	int touch_ret, 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);
+
+	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) {
+			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);
+
+		ret = devm_request_irq(dev, virq,
+				       mxs_lradc_ts_handle_irq,
+				       0, mxs_lradc_ts_irq_names[i], ts);
+		if (ret)
+			return ret;
+	}
+
+	if (!touch_ret) {
+		ret = mxs_lradc_ts_register(ts);
+		if (!ret)
+			goto error;
+	}
+
+	return 0;
+
+error:
+	mxs_lradc_ts_stop(ts);
+
+	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

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