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: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 135 insertions, 37 deletions

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index a3771607ead5..16031933a8f6 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) {
@@ -1009,16 +1073,26 @@ 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
@@ -1044,17 +1118,28 @@ 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) {
@@ -1145,15 +1230,25 @@ 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);
 
@@ -1202,8 +1297,11 @@ 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)