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: Anatolij Gustschin <agust@xxxxxxx>
---
Changes since first version:
- provide better changelog as requested by Dmitry
- fix to long comment line (it was over 80 characters)
drivers/input/touchscreen/ads7846.c | 173 +++++++++++++++++++++++++++--------
1 files changed, 136 insertions(+), 37 deletions(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 69210cb..8ab90dd 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -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.
*/
- x = packet->tc.x;
- y = packet->tc.y;
- z1 = packet->tc.z1;
- z2 = packet->tc.z2;
+ 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.
- */
- val = be16_to_cpup((__be16 *)t->rx_buf) >> 3;
+ 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) {
@@ -1008,16 +1072,26 @@ static int __devinit ads7846_probe(struct spi_device *spi)
spi_message_init(m);
- /* y- still on; turn on only y+ (and ADC) */
- packet->read_y = READ_Y(vref);
- x->tx_buf = &packet->read_y;
- x->len = 1;
- spi_message_add_tail(x, 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;
+ x->len = 1;
+ spi_message_add_tail(x, m);
- x++;
- x->rx_buf = &packet->tc.y;
- x->len = 2;
- spi_message_add_tail(x, m);
+ x++;
+ 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
@@ -1043,17 +1117,28 @@ static int __devinit ads7846_probe(struct spi_device *spi)
m++;
spi_message_init(m);
- /* turn y- off, x+ on, then leave in lowpower */
- x++;
- packet->read_x = READ_X(vref);
- x->tx_buf = &packet->read_x;
- x->len = 1;
- spi_message_add_tail(x, 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);
+ x->tx_buf = &packet->read_x;
+ x->len = 1;
+ spi_message_add_tail(x, m);
- x++;
- x->rx_buf = &packet->tc.x;
- x->len = 2;
- spi_message_add_tail(x, m);
+ x++;
+ x->rx_buf = &packet->tc.x;
+ x->len = 2;
+ spi_message_add_tail(x, m);
+ }
/* ... maybe discard first sample ... */
if (pdata->settle_delay_usecs) {
@@ -1144,15 +1229,25 @@ static int __devinit ads7846_probe(struct spi_device *spi)
m++;
spi_message_init(m);
- x++;
- packet->pwrdown = PWRDOWN;
- x->tx_buf = &packet->pwrdown;
- x->len = 1;
- spi_message_add_tail(x, 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;
+ x->len = 1;
+ spi_message_add_tail(x, m);
+
+ x++;
+ x->rx_buf = &packet->dummy;
+ x->len = 2;
+ }
- x++;
- x->rx_buf = &packet->dummy;
- x->len = 2;
CS_CHANGE(*x);
spi_message_add_tail(x, m);
@@ -1199,8 +1294,12 @@ 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.
*/
- (void) ads7846_read12_ser(&spi->dev,
- READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
+ 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);
+ }
err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
if (err)
--
1.7.0.4
--
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