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Commit 3eac5c7e authored by Anatolij Gustschin's avatar Anatolij Gustschin Committed by Dmitry Torokhov
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Input: ads7846 - extend the driver for ads7845 controller support 



ADS7845 is a controller for 5-wire touch screens and somewhat
different from 7846. It requires three serial communications to
accomplish one complete conversion. Unlike 7846 it doesn't allow
Z1-/Z2- position measurement.

The patch extends the ads7846 driver to also support ads7845.
The packet struct is extended to contain needed command and
conversion buffers. ads7846_rx() and ads7846_rx_val() now
differentiate between 7845 and 7846 case. ads7846_probe() is
modified to setup ads7845 specific command and conversion
messages and to switch ads7845 into power-down mode, since
this is needed to be prepared to respond to pendown interrupts.

Signed-off-by: default avatarAnatolij Gustschin <agust@denx.de>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent 0f622bf4

drivers/input/touchscreen/ads7846.c

+135 −37
Original line number Diff line number Diff line
@@ -68,6 +68,8 @@ struct ts_event { 
	u16	y;

	u16	z1, z2;

	int	ignore;

	u8	x_buf[3];

	u8	y_buf[3];

};



/*
@@ -79,6 +81,8 @@ struct ads7846_packet { 
	u8			read_x, read_y, read_z1, read_z2, pwrdown;

	u16			dummy;		/* for the pwrdown read */

	struct ts_event		tc;

	/* for ads7845 with mpc5121 psc spi we use 3-byte buffers */

	u8			read_x_cmd[3], read_y_cmd[3], pwrdown_cmd[3];

};



struct ads7846 {
@@ -207,6 +211,14 @@ struct ser_req { 
	struct spi_transfer	xfer[6];

};



struct ads7845_ser_req {

	u8			command[3];

	u8			pwrdown[3];

	u8			sample[3];

	struct spi_message	msg;

	struct spi_transfer	xfer[2];

};



static void ads7846_enable(struct ads7846 *ts);

static void ads7846_disable(struct ads7846 *ts);
@@ -287,6 +299,41 @@ static int ads7846_read12_ser(struct device *dev, unsigned command) 
	return status;

}



static int ads7845_read12_ser(struct device *dev, unsigned command)

{

	struct spi_device	*spi = to_spi_device(dev);

	struct ads7846		*ts = dev_get_drvdata(dev);

	struct ads7845_ser_req	*req = kzalloc(sizeof *req, GFP_KERNEL);

	int			status;



	if (!req)

		return -ENOMEM;



	spi_message_init(&req->msg);



	req->command[0] = (u8) command;

	req->xfer[0].tx_buf = req->command;

	req->xfer[0].rx_buf = req->sample;

	req->xfer[0].len = 3;

	spi_message_add_tail(&req->xfer[0], &req->msg);



	ts->irq_disabled = 1;

	disable_irq(spi->irq);

	status = spi_sync(spi, &req->msg);

	ts->irq_disabled = 0;

	enable_irq(spi->irq);



	if (status == 0) {

		/* BE12 value, then padding */

		status = be16_to_cpu(*((u16 *)&req->sample[1]));

		status = status >> 3;

		status &= 0x0fff;

	}



	kfree(req);

	return status;

}



#if defined(CONFIG_HWMON) || defined(CONFIG_HWMON_MODULE)



#define SHOW(name, var, adjust) static ssize_t \
@@ -540,10 +587,17 @@ static void ads7846_rx(void *ads) 
	/* ads7846_rx_val() did in-place conversion (including byteswap) from

	 * on-the-wire format as part of debouncing to get stable readings.

	 */

	if (ts->model == 7845) {

		x = *(u16 *)packet->tc.x_buf;

		y = *(u16 *)packet->tc.y_buf;

		z1 = 0;

		z2 = 0;

	} else {

		x = packet->tc.x;

		y = packet->tc.y;

		z1 = packet->tc.z1;

		z2 = packet->tc.z2;

	}



	/* range filtering */

	if (x == MAX_12BIT)
@@ -551,6 +605,12 @@ static void ads7846_rx(void *ads) 


	if (ts->model == 7843) {

		Rt = ts->pressure_max / 2;

	} else if (ts->model == 7845) {

		if (get_pendown_state(ts))

			Rt = ts->pressure_max / 2;

		else

			Rt = 0;

		dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt);

	} else if (likely(x && z1)) {

		/* compute touch pressure resistance using equation #2 */

		Rt = z2;
@@ -671,10 +731,14 @@ static void ads7846_rx_val(void *ads) 
	m = &ts->msg[ts->msg_idx];

	t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);



	/* adjust:  on-wire is a must-ignore bit, a BE12 value, then padding;

	 * built from two 8 bit values written msb-first.

	if (ts->model == 7845) {

		val = be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;

	} else {

		/* 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_cpup((__be16 *)t->rx_buf) >> 3;

	}



	action = ts->filter(ts->filter_data, ts->msg_idx, &val);

	switch (action) {
@@ -1009,6 +1073,15 @@ static int __devinit ads7846_probe(struct spi_device *spi) 


	spi_message_init(m);



	if (ts->model == 7845) {

		packet->read_y_cmd[0] = READ_Y(vref);

		packet->read_y_cmd[1] = 0;

		packet->read_y_cmd[2] = 0;

		x->tx_buf = &packet->read_y_cmd[0];

		x->rx_buf = &packet->tc.y_buf[0];

		x->len = 3;

		spi_message_add_tail(x, m);

	} else {

		/* y- still on; turn on only y+ (and ADC) */

		packet->read_y = READ_Y(vref);

		x->tx_buf = &packet->read_y;
@@ -1019,6 +1092,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
		x->rx_buf = &packet->tc.y;

		x->len = 2;

		spi_message_add_tail(x, m);

	}



	/* the first sample after switching drivers can be low quality;

	 * optionally discard it, using a second one after the signals
@@ -1044,6 +1118,16 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	m++;

	spi_message_init(m);



	if (ts->model == 7845) {

		x++;

		packet->read_x_cmd[0] = READ_X(vref);

		packet->read_x_cmd[1] = 0;

		packet->read_x_cmd[2] = 0;

		x->tx_buf = &packet->read_x_cmd[0];

		x->rx_buf = &packet->tc.x_buf[0];

		x->len = 3;

		spi_message_add_tail(x, m);

	} else {

		/* turn y- off, x+ on, then leave in lowpower */

		x++;

		packet->read_x = READ_X(vref);
@@ -1055,6 +1139,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
		x->rx_buf = &packet->tc.x;

		x->len = 2;

		spi_message_add_tail(x, m);

	}



	/* ... maybe discard first sample ... */

	if (pdata->settle_delay_usecs) {
@@ -1145,6 +1230,14 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	m++;

	spi_message_init(m);



	if (ts->model == 7845) {

		x++;

		packet->pwrdown_cmd[0] = PWRDOWN;

		packet->pwrdown_cmd[1] = 0;

		packet->pwrdown_cmd[2] = 0;

		x->tx_buf = &packet->pwrdown_cmd[0];

		x->len = 3;

	} else {

		x++;

		packet->pwrdown = PWRDOWN;

		x->tx_buf = &packet->pwrdown;
@@ -1154,6 +1247,8 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
		x++;

		x->rx_buf = &packet->dummy;

		x->len = 2;

	}



	CS_CHANGE(*x);

	spi_message_add_tail(x, m);
@@ -1202,6 +1297,9 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	/* take a first sample, leaving nPENIRQ active and vREF off; avoid

	 * the touchscreen, in case it's not connected.

	 */

	if (ts->model == 7845)

		ads7845_read12_ser(&spi->dev, PWRDOWN);

	else

		(void) ads7846_read12_ser(&spi->dev,

				READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);