path: root/drivers/input/touchscreen/mxs-lradc-ts.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Freescale MXS LRADC touchscreen driver
 *
 * Copyright (c) 2012 DENX Software Engineering, GmbH.
 * Copyright (c) 2017 Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
 *
 * Authors:
 *  Marek Vasut <marex@denx.de>
 *  Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
 */

#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>

static const char * const 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;
};

struct state_info {
	u32		mask;
	u32		bit;
	u32		x_plate;
	u32		y_plate;
	u32		pressure;
};

static struct state_info info[] = {
	{LRADC_CTRL0_MX23_PLATE_MASK, LRADC_CTRL0_MX23_TOUCH_DETECT_ENABLE,
	 LRADC_CTRL0_MX23_XP | LRADC_CTRL0_MX23_XM,
	 LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_YM,
	 LRADC_CTRL0_MX23_YP | LRADC_CTRL0_MX23_XM},
	{LRADC_CTRL0_MX28_PLATE_MASK, LRADC_CTRL0_MX28_TOUCH_DETECT_ENABLE,
	 LRADC_CTRL0_MX28_XPPSW | LRADC_CTRL0_MX28_XNNSW,
	 LRADC_CTRL0_MX28_YPPSW | LRADC_CTRL0_MX28_YNNSW,
	 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) &