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Commit da970e69 authored by Imre Deak's avatar Imre Deak Committed by Dmitry Torokhov
Browse files

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

drivers/input/touchscreen/ads7846.c

+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");

include/linux/spi/ads7846.h

+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);

};