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Commit da970e69 authored by Imre Deak's avatar Imre Deak Committed by Dmitry Torokhov
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Input: ads7846 - pluggable filtering logic



Some LCDs like the LS041Y3 require a customized filtering
logic for reliable readings, so make the filtering function
replacable through platform specific hooks.

Signed-off-by: default avatarImre Deak <imre.deak@solidboot.com>
Signed-off-by: default avatarJuha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent 78a56aab
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+95 −40
Original line number Diff line number Diff line
@@ -63,11 +63,11 @@ struct ts_event {
	/* For portability, we can't read 12 bit values using SPI (which
	 * would make the controller deliver them as native byteorder u16
	 * with msbs zeroed).  Instead, we read them as two 8-bit values,
	 * which need byteswapping then range adjustment.
	 * *** WHICH NEED BYTESWAPPING *** and range adjustment.
	 */
	__be16 x;
	__be16 y;
	__be16 z1, z2;
	u16	x;
	u16	y;
	u16	z1, z2;
	int    ignore;
};

@@ -106,6 +106,9 @@ struct ads7846 {
	unsigned		irq_disabled:1;	/* P: lock */
	unsigned		disabled:1;

	int			(*filter)(void *data, int data_idx, int *val);
	void			*filter_data;
	void			(*filter_cleanup)(void *data);
	int			(*get_pendown_state)(void);
};

@@ -379,13 +382,13 @@ static void ads7846_rx(void *ads)
	u16			x, y, z1, z2;
	unsigned long		flags;

	/* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
	 * built from two 8 bit values written msb-first.
	/* ads7846_rx_val() did in-place conversion (including byteswap) from
	 * on-the-wire format as part of debouncing to get stable readings.
	 */
	x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
	y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
	z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
	z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;
	x = ts->tc.x;
	y = ts->tc.y;
	z1 = ts->tc.z1;
	z2 = ts->tc.z2;

	/* range filtering */
	if (x == MAX_12BIT)
@@ -453,50 +456,85 @@ static void ads7846_rx(void *ads)
	spin_unlock_irqrestore(&ts->lock, flags);
}

static void ads7846_debounce(void *ads)
static int ads7846_debounce(void *ads, int data_idx, int *val)
{
	struct ads7846		*ts = ads;
	struct spi_message	*m;
	struct spi_transfer	*t;
	int			val;
	int			status;

	m = &ts->msg[ts->msg_idx];
	t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
	val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
	if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
	if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
		/* Start over collecting consistent readings. */
		ts->read_rep = 0;
		/* Repeat it, if this was the first read or the read
		 * wasn't consistent enough. */
		if (ts->read_cnt < ts->debounce_max) {
			ts->last_read = val;
			ts->last_read = *val;
			ts->read_cnt++;
			return ADS7846_FILTER_REPEAT;
		} else {
			/* Maximum number of debouncing reached and still
			 * not enough number of consistent readings. Abort
			 * the whole sample, repeat it in the next sampling
			 * period.
			 */
			ts->tc.ignore = 1;
			ts->read_cnt = 0;
			/* Last message will contain ads7846_rx() as the
			 * completion function.
			 */
			m = ts->last_msg;
			return ADS7846_FILTER_IGNORE;
		}
		/* Start over collecting consistent readings. */
		ts->read_rep = 0;
	} else {
		if (++ts->read_rep > ts->debounce_rep) {
			/* Got a good reading for this coordinate,
			 * go for the next one. */
			ts->tc.ignore = 0;
			ts->msg_idx++;
			ts->read_cnt = 0;
			ts->read_rep = 0;
			m++;
		} else
			return ADS7846_FILTER_OK;
		} else {
			/* Read more values that are consistent. */
			ts->read_cnt++;
			return ADS7846_FILTER_REPEAT;
		}
	}
}

static int ads7846_no_filter(void *ads, int data_idx, int *val)
{
	return ADS7846_FILTER_OK;
}

static void ads7846_rx_val(void *ads)
{
	struct ads7846 *ts = ads;
	struct spi_message *m;
	struct spi_transfer *t;
	u16 *rx_val;
	int val;
	int action;
	int status;

	m = &ts->msg[ts->msg_idx];
	t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
	rx_val = t->rx_buf;

	/* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;
	 * built from two 8 bit values written msb-first.
	 */
	val = be16_to_cpu(*rx_val) >> 3;

	action = ts->filter(ts->filter_data, ts->msg_idx, &val);
	switch (action) {
	case ADS7846_FILTER_REPEAT:
		break;
	case ADS7846_FILTER_IGNORE:
		ts->tc.ignore = 1;
		/* Last message will contain ads7846_rx() as the
		 * completion function.
		 */
		m = ts->last_msg;
		break;
	case ADS7846_FILTER_OK:
		*rx_val = val;
		ts->tc.ignore = 0;
		m = &ts->msg[++ts->msg_idx];
		break;
	default:
		BUG();
	}
	status = spi_async(ts->spi, m);
	if (status)
@@ -689,14 +727,25 @@ static int __devinit ads7846_probe(struct spi_device *spi)
	ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
	ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
	ts->pressure_max = pdata->pressure_max ? : ~0;
	if (pdata->debounce_max) {

	if (pdata->filter != NULL) {
		if (pdata->filter_init != NULL) {
			err = pdata->filter_init(pdata, &ts->filter_data);
			if (err < 0)
				goto err_free_mem;
		}
		ts->filter = pdata->filter;
		ts->filter_cleanup = pdata->filter_cleanup;
	} else if (pdata->debounce_max) {
		ts->debounce_max = pdata->debounce_max;
		if (ts->debounce_max < 2)
			ts->debounce_max = 2;
		ts->debounce_tol = pdata->debounce_tol;
		ts->debounce_rep = pdata->debounce_rep;
		if (ts->debounce_rep > ts->debounce_max + 1)
			ts->debounce_rep = ts->debounce_max - 1;
		ts->filter = ads7846_debounce;
		ts->filter_data = ts;
	} else
		ts->debounce_tol = ~0;
		ts->filter = ads7846_no_filter;
	ts->get_pendown_state = pdata->get_pendown_state;

	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
@@ -737,7 +786,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
	x->len = 2;
	spi_message_add_tail(x, m);

	m->complete = ads7846_debounce;
	m->complete = ads7846_rx_val;
	m->context = ts;

	m++;
@@ -755,7 +804,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
	x->len = 2;
	spi_message_add_tail(x, m);

	m->complete = ads7846_debounce;
	m->complete = ads7846_rx_val;
	m->context = ts;

	/* turn y+ off, x- on; we'll use formula #2 */
@@ -774,7 +823,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
		x->len = 2;
		spi_message_add_tail(x, m);

		m->complete = ads7846_debounce;
		m->complete = ads7846_rx_val;
		m->context = ts;

		m++;
@@ -791,7 +840,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
		x->len = 2;
		spi_message_add_tail(x, m);

		m->complete = ads7846_debounce;
		m->complete = ads7846_rx_val;
		m->context = ts;
	}

@@ -820,7 +869,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
			spi->dev.driver->name, ts)) {
		dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
		err = -EBUSY;
		goto err_free_mem;
		goto err_cleanup_filter;
	}

	dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
@@ -856,6 +905,9 @@ static int __devinit ads7846_probe(struct spi_device *spi)
	sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
 err_free_irq:
	free_irq(spi->irq, ts);
 err_cleanup_filter:
	if (ts->filter_cleanup)
		ts->filter_cleanup(ts->filter_data);
 err_free_mem:
	input_free_device(input_dev);
	kfree(ts);
@@ -876,6 +928,9 @@ static int __devexit ads7846_remove(struct spi_device *spi)
	/* suspend left the IRQ disabled */
	enable_irq(ts->spi->irq);

	if (ts->filter_cleanup)
		ts->filter_cleanup(ts->filter_data);

	kfree(ts);

	dev_dbg(&spi->dev, "unregistered touchscreen\n");
+10 −0
Original line number Diff line number Diff line
@@ -5,6 +5,12 @@
 *
 * It's OK if the min/max values are zero.
 */
enum ads7846_filter {
	ADS7846_FILTER_OK,
	ADS7846_FILTER_REPEAT,
	ADS7846_FILTER_IGNORE,
};

struct ads7846_platform_data {
	u16	model;			/* 7843, 7845, 7846. */
	u16	vref_delay_usecs;	/* 0 for external vref; etc */
@@ -21,5 +27,9 @@ struct ads7846_platform_data {
	u16	debounce_rep;		/* additional consecutive good readings
					 * required after the first two */
	int	(*get_pendown_state)(void);
	int	(*filter_init)	(struct ads7846_platform_data *pdata,
				 void **filter_data);
	int	(*filter)	(void *filter_data, int data_idx, int *val);
	void	(*filter_cleanup)(void *filter_data);
};