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Commit d93f70b2 authored by David Brownell's avatar David Brownell Committed by Dmitry Torokhov
Browse files

Input: ads7846 - assorted updates 



This updates the ads7846 touchscreen driver:
  - to allow faster clocking (this driver doesn't push sample rates);
  - bugfixes the conversion of spi_transfer to lists;
  - some dma-unsafe command buffers are fixed.

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarDmitry Torokhov <dtor@mail.ru>
parent a90f7e98

drivers/input/touchscreen/ads7846.c

+44 −24
Original line number Diff line number Diff line
@@ -48,10 +48,13 @@ 


#define	TS_POLL_PERIOD	msecs_to_jiffies(10)



/* this driver doesn't aim at the peak continuous sample rate */

#define	SAMPLE_BITS	(8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)



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-byte values,

	 * with msbs zeroed).  Instead, we read them as two 8-bit values,

	 * which need byteswapping then range adjustment.

	 */

	__be16 x;
@@ -68,6 +71,7 @@ struct ads7846 { 
	u16			vref_delay_usecs;

	u16			x_plate_ohms;



	u8			read_x, read_y, read_z1, read_z2;

	struct ts_event		tc;



	struct spi_transfer	xfer[8];
@@ -117,10 +121,10 @@ struct ads7846 { 
#define	READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \

	| ADS_12_BIT | ADS_DFR)



static const u8	read_y  = READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON;

static const u8	read_z1 = READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON;

static const u8	read_z2 = READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON;

static const u8	read_x  = READ_12BIT_DFR(x)  | ADS_PD10_PDOWN;	/* LAST */

#define	READ_Y	(READ_12BIT_DFR(y)  | ADS_PD10_ADC_ON)

#define	READ_Z1	(READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)

#define	READ_Z2	(READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)

#define	READ_X	(READ_12BIT_DFR(x)  | ADS_PD10_PDOWN)	/* LAST */



/* single-ended samples need to first power up reference voltage;

 * we leave both ADC and VREF powered
@@ -128,8 +132,8 @@ static const u8 read_x = READ_12BIT_DFR(x) | ADS_PD10_PDOWN; /* LAST */ 
#define	READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \

	| ADS_12_BIT | ADS_SER)



static const u8	ref_on = READ_12BIT_DFR(x) | ADS_PD10_ALL_ON;

static const u8	ref_off = READ_12BIT_DFR(y) | ADS_PD10_PDOWN;

#define	REF_ON	(READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)

#define	REF_OFF	(READ_12BIT_DFR(y) | ADS_PD10_PDOWN)



/*--------------------------------------------------------------------------*/
@@ -138,7 +142,9 @@ static const u8 ref_off = READ_12BIT_DFR(y) | ADS_PD10_PDOWN; 
 */



struct ser_req {

	u8			ref_on;

	u8			command;

	u8			ref_off;

	u16			scratch;

	__be16			sample;

	struct spi_message	msg;
@@ -160,7 +166,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command) 
	INIT_LIST_HEAD(&req->msg.transfers);



	/* activate reference, so it has time to settle; */

	req->xfer[0].tx_buf = &ref_on;

	req->ref_on = REF_ON;

	req->xfer[0].tx_buf = &req->ref_on;

	req->xfer[0].len = 1;

	req->xfer[1].rx_buf = &req->scratch;

	req->xfer[1].len = 2;
@@ -182,7 +189,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command) 
	/* REVISIT:  take a few more samples, and compare ... */



	/* turn off reference */

	req->xfer[4].tx_buf = &ref_off;

	req->ref_off = REF_OFF;

	req->xfer[4].tx_buf = &req->ref_off;

	req->xfer[4].len = 1;

	req->xfer[5].rx_buf = &req->scratch;

	req->xfer[5].len = 2;
@@ -400,7 +408,6 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	struct input_dev		*input_dev;

	struct ads7846_platform_data	*pdata = spi->dev.platform_data;

	struct spi_transfer		*x;

	int				i;

	int				err;



	if (!spi->irq) {
@@ -414,9 +421,9 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	}



	/* don't exceed max specified sample rate */

	if (spi->max_speed_hz > (125000 * 16)) {

	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {

		dev_dbg(&spi->dev, "f(sample) %d KHz?\n",

				(spi->max_speed_hz/16)/1000);

				(spi->max_speed_hz/SAMPLE_BITS)/1000);

		return -EINVAL;

	}
@@ -469,45 +476,58 @@ static int __devinit ads7846_probe(struct spi_device *spi) 
	/* set up the transfers to read touchscreen state; this assumes we

	 * use formula #2 for pressure, not #3.

	 */

	INIT_LIST_HEAD(&ts->msg.transfers);

	x = ts->xfer;



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

	x->tx_buf = &read_y;

	ts->read_y = READ_Y;

	x->tx_buf = &ts->read_y;

	x->len = 1;

	spi_message_add_tail(x, &ts->msg);



	x++;

	x->rx_buf = &ts->tc.y;

	x->len = 2;

	x++;

	spi_message_add_tail(x, &ts->msg);



	/* turn y+ off, x- on; we'll use formula #2 */

	if (ts->model == 7846) {

		x->tx_buf = &read_z1;

		x++;

		ts->read_z1 = READ_Z1;

		x->tx_buf = &ts->read_z1;

		x->len = 1;

		spi_message_add_tail(x, &ts->msg);



		x++;

		x->rx_buf = &ts->tc.z1;

		x->len = 2;

		x++;

		spi_message_add_tail(x, &ts->msg);



		x->tx_buf = &read_z2;

		x++;

		ts->read_z2 = READ_Z2;

		x->tx_buf = &ts->read_z2;

		x->len = 1;

		spi_message_add_tail(x, &ts->msg);



		x++;

		x->rx_buf = &ts->tc.z2;

		x->len = 2;

		x++;

		spi_message_add_tail(x, &ts->msg);

	}



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

	x->tx_buf = &read_x;

	x++;

	ts->read_x = READ_X;

	x->tx_buf = &ts->read_x;

	x->len = 1;

	spi_message_add_tail(x, &ts->msg);



	x++;

	x->rx_buf = &ts->tc.x;

	x->len = 2;

	x++;



	CS_CHANGE(x[-1]);

	CS_CHANGE(*x);

	spi_message_add_tail(x, &ts->msg);



	for (i = 0; i < x - ts->xfer; i++)

		spi_message_add_tail(&ts->xfer[i], &ts->msg);

	ts->msg.complete = ads7846_rx;

	ts->msg.context = ts;