4 files changed, 653 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 21d55ed4b88a..2c674023a6ac 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -11,6 +11,19 @@ menuconfig INPUT_TOUCHSCREEN
 
 if INPUT_TOUCHSCREEN
 
+config TOUCHSCREEN_ADS7846
+        tristate "ADS 7846 based touchscreens"
+        depends on SPI_MASTER
+        help
+          Say Y here if you have a touchscreen interface using the
+          ADS7846 controller, and your board-specific initialization
+          code includes that in its table of SPI devices.
+
+          If unsure, say N (but it's safe to say "Y").
+
+          To compile this driver as a module, choose M here: the
+          module will be called ads7846.
+
 config TOUCHSCREEN_BITSY
         tristate "Compaq iPAQ H3600 (Bitsy) touchscreen"
         depends on SA1100_BITSY
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 6842869c9a26..5e5557c43121 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -4,6 +4,7 @@
 
 # Each configuration option enables a list of files.
 
+obj-$(CONFIG_TOUCHSCREEN_ADS7846)       += ads7846.o
 obj-$(CONFIG_TOUCHSCREEN_BITSY) += h3600_ts_input.o
 obj-$(CONFIG_TOUCHSCREEN_CORGI) += corgi_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GUNZE) += gunze.o
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
new file mode 100644
index 000000000000..24ff6c5a4021
--- /dev/null
+++ b/drivers/input/touchscreen/ads7846.c
@@ -0,0 +1,621 @@
+/*
+ * ADS7846 based touchscreen and sensor driver
+ *
+ * Copyright (c) 2005 David Brownell
+ *
+ * Using code from:
+ *  - corgi_ts.c
+ *      Copyright (C) 2004-2005 Richard Purdie
+ *  - omap_ts.[hc], ads7846.h, ts_osk.c
+ *      Copyright (C) 2002 MontaVista Software
+ *      Copyright (C) 2004 Texas Instruments
+ *      Copyright (C) 2005 Dirk Behme
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/ads7846.h>
+
+#ifdef  CONFIG_ARM
+#include <asm/mach-types.h>
+#ifdef  CONFIG_ARCH_OMAP
+#include <asm/arch/gpio.h>
+#endif
+
+#else
+#define set_irq_type(irq,type)  do{}while(0)
+#endif
+
+
+/*
+ * This code has been lightly tested on an ads7846.
+ * Support for ads7843 and ads7845 has only been stubbed in.
+ *
+ * Not yet done:  investigate the values reported.  Are x/y/pressure
+ * event values sane enough for X11?  How accurate are the temperature
+ * and voltage readings?  (System-specific calibration should support
+ * accuracy of 0.3 degrees C; otherwise it's 2.0 degrees.)
+ *
+ * app note sbaa036 talks in more detail about accurate sampling...
+ * that ought to help in situations like LCDs inducing noise (which
+ * can also be helped by using synch signals) and more generally.
+ */
+
+#define TS_POLL_PERIOD  msecs_to_jiffies(10)
+
+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,
+         * which need byteswapping then range adjustment.
+         */
+        __be16 x;
+        __be16 y;
+        __be16 z1, z2;
+};
+
+struct ads7846 {
+        struct input_dev        input;
+        char                    phys[32];
+
+        struct spi_device       *spi;
+        u16                     model;
+        u16                     vref_delay_usecs;
+        u16                     x_plate_ohms;
+
+        struct ts_event         tc;
+
+        struct spi_transfer     xfer[8];
+        struct spi_message      msg;
+
+        spinlock_t              lock;
+        struct timer_list       timer;          /* P: lock */
+        unsigned                pendown:1;      /* P: lock */
+        unsigned                pending:1;      /* P: lock */
+// FIXME remove "irq_disabled"
+        unsigned                irq_disabled:1; /* P: lock */
+};
+
+/* leave chip selected when we're done, for quicker re-select? */
+#if     0
+#define CS_CHANGE(xfer) ((xfer).cs_change = 1)
+#else
+#define CS_CHANGE(xfer) ((xfer).cs_change = 0)
+#endif
+
+/*--------------------------------------------------------------------------*/
+
+/* The ADS7846 has touchscreen and other sensors.
+ * Earlier ads784x chips are somewhat compatible.
+ */
+#define ADS_START               (1 << 7)
+#define ADS_A2A1A0_d_y          (1 << 4)        /* differential */
+#define ADS_A2A1A0_d_z1         (3 << 4)        /* differential */
+#define ADS_A2A1A0_d_z2         (4 << 4)        /* differential */
+#define ADS_A2A1A0_d_x          (5 << 4)        /* differential */
+#define ADS_A2A1A0_temp0        (0 << 4)        /* non-differential */
+#define ADS_A2A1A0_vbatt        (2 << 4)        /* non-differential */
+#define ADS_A2A1A0_vaux         (6 << 4)        /* non-differential */
+#define ADS_A2A1A0_temp1        (7 << 4)        /* non-differential */
+#define ADS_8_BIT               (1 << 3)
+#define ADS_12_BIT              (0 << 3)
+#define ADS_SER                 (1 << 2)        /* non-differential */
+#define ADS_DFR                 (0 << 2)        /* differential */
+#define ADS_PD10_PDOWN          (0 << 0)        /* lowpower mode + penirq */
+#define ADS_PD10_ADC_ON         (1 << 0)        /* ADC on */
+#define ADS_PD10_REF_ON         (2 << 0)        /* vREF on + penirq */
+#define ADS_PD10_ALL_ON         (3 << 0)        /* ADC + vREF on */
+
+#define MAX_12BIT       ((1<<12)-1)
+
+/* leave ADC powered up (disables penirq) between differential samples */
+#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 */
+
+/* single-ended samples need to first power up reference voltage;
+ * we leave both ADC and VREF powered
+ */
+#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;
+
+/*--------------------------------------------------------------------------*/
+
+/*
+ * Non-touchscreen sensors only use single-ended conversions.
+ */
+
+struct ser_req {
+        u8                      command;
+        u16                     scratch;
+        __be16                  sample;
+        struct spi_message      msg;
+        struct spi_transfer     xfer[6];
+};
+
+static int ads7846_read12_ser(struct device *dev, unsigned command)
+{
+        struct spi_device       *spi = to_spi_device(dev);
+        struct ads7846          *ts = dev_get_drvdata(dev);
+        struct ser_req          *req = kzalloc(sizeof *req, SLAB_KERNEL);
+        int                     status;
+        int                     sample;
+
+        if (!req)
+                return -ENOMEM;
+
+        /* activate reference, so it has time to settle; */
+        req->xfer[0].tx_buf = &ref_on;
+        req->xfer[0].len = 1;
+        req->xfer[1].rx_buf = &req->scratch;
+        req->xfer[1].len = 2;
+
+        /*
+         * for external VREF, 0 usec (and assume it's always on);
+         * for 1uF, use 800 usec;
+         * no cap, 100 usec.
+         */
+        req->xfer[1].delay_usecs = ts->vref_delay_usecs;
+
+        /* take sample */
+        req->command = (u8) command;
+        req->xfer[2].tx_buf = &req->command;
+        req->xfer[2].len = 1;
+        req->xfer[3].rx_buf = &req->sample;
+        req->xfer[3].len = 2;
+
+        /* REVISIT:  take a few more samples, and compare ... */
+
+        /* turn off reference */
+        req->xfer[4].tx_buf = &ref_off;
+        req->xfer[4].len = 1;
+        req->xfer[5].rx_buf = &req->scratch;
+        req->xfer[5].len = 2;
+
+        CS_CHANGE(req->xfer[5]);
+
+        /* group all the transfers together, so we can't interfere with
+         * reading touchscreen state; disable penirq while sampling
+         */
+        req->msg.transfers = req->xfer;
+        req->msg.n_transfer = 6;
+
+        disable_irq(spi->irq);
+        status = spi_sync(spi, &req->msg);
+        enable_irq(spi->irq);
+
+        if (req->msg.status)
+                status = req->msg.status;
+        sample = be16_to_cpu(req->sample);
+        sample = sample >> 4;
+        kfree(req);
+
+        return status ? status : sample;
+}
+
+#define SHOW(name) static ssize_t \
+name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
+{ \
+        ssize_t v = ads7846_read12_ser(dev, \
+                        READ_12BIT_SER(name) | ADS_PD10_ALL_ON); \
+        if (v < 0) \
+                return v; \
+        return sprintf(buf, "%u\n", (unsigned) v); \
+} \
+static DEVICE_ATTR(name, S_IRUGO, name ## _show, NULL);
+
+SHOW(temp0)
+SHOW(temp1)
+SHOW(vaux)
+SHOW(vbatt)
+
+/*--------------------------------------------------------------------------*/
+
+/*
+ * PENIRQ only kicks the timer.  The timer only reissues the SPI transfer,
+ * to retrieve touchscreen status.
+ *
+ * The SPI transfer completion callback does the real work.  It reports
+ * touchscreen events and reactivates the timer (or IRQ) as appropriate.
+ */
+
+static void ads7846_rx(void *ads)
+{
+        struct ads7846  *ts = ads;
+        unsigned        Rt;
+        unsigned        sync = 0;
+        u16             x, y, z1, z2;
+        unsigned long   flags;
+
+        /* adjust:  12 bit samples (left aligned), built from
+         * two 8 bit values writen msb-first.
+         */
+        x = be16_to_cpu(ts->tc.x) >> 4;
+        y = be16_to_cpu(ts->tc.y) >> 4;
+        z1 = be16_to_cpu(ts->tc.z1) >> 4;
+        z2 = be16_to_cpu(ts->tc.z2) >> 4;
+
+        /* range filtering */
+        if (x == MAX_12BIT)
+                x = 0;
+
+        if (x && z1 && ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
+                /* compute touch pressure resistance using equation #2 */
+                Rt = z2;
+                Rt -= z1;
+                Rt *= x;
+                Rt *= ts->x_plate_ohms;
+                Rt /= z1;
+                Rt = (Rt + 2047) >> 12;
+        } else
+                Rt = 0;
+
+        /* NOTE:  "pendown" is inferred from pressure; we don't rely on
+         * being able to check nPENIRQ status, or "friendly" trigger modes
+         * (both-edges is much better than just-falling or low-level).
+         *
+         * REVISIT:  some boards may require reading nPENIRQ; it's
+         * needed on 7843.  and 7845 reads pressure differently...
+         *
+         * REVISIT:  the touchscreen might not be connected; this code
+         * won't notice that, even if nPENIRQ never fires ...
+         */
+        if (!ts->pendown && Rt != 0) {
+                input_report_key(&ts->input, BTN_TOUCH, 1);
+                sync = 1;
+        } else if (ts->pendown && Rt == 0) {
+                input_report_key(&ts->input, BTN_TOUCH, 0);
+                sync = 1;
+        }
+
+        if (Rt) {
+                input_report_abs(&ts->input, ABS_X, x);
+                input_report_abs(&ts->input, ABS_Y, y);
+                input_report_abs(&ts->input, ABS_PRESSURE, Rt);
+                sync = 1;
+        }
+        if (sync)
+                input_sync(&ts->input);
+
+#ifdef  VERBOSE
+        if (Rt || ts->pendown)
+                pr_debug("%s: %d/%d/%d%s\n", ts->spi->dev.bus_id,
+                        x, y, Rt, Rt ? "" : " UP");
+#endif
+
+        /* don't retrigger while we're suspended */
+        spin_lock_irqsave(&ts->lock, flags);
+
+        ts->pendown = (Rt != 0);
+        ts->pending = 0;
+
+        if (ts->spi->dev.power.power_state.event == PM_EVENT_ON) {
+                if (ts->pendown)
+                        mod_timer(&ts->timer, jiffies + TS_POLL_PERIOD);
+                else if (ts->irq_disabled) {
+                        ts->irq_disabled = 0;
+                        enable_irq(ts->spi->irq);
+                }
+        }
+
+        spin_unlock_irqrestore(&ts->lock, flags);
+}
+
+static void ads7846_timer(unsigned long handle)
+{
+        struct ads7846  *ts = (void *)handle;
+        int             status = 0;
+        unsigned long   flags;
+
+        spin_lock_irqsave(&ts->lock, flags);
+        if (!ts->pending) {
+                ts->pending = 1;
+                if (!ts->irq_disabled) {
+                        ts->irq_disabled = 1;
+                        disable_irq(ts->spi->irq);
+                }
+                status = spi_async(ts->spi, &ts->msg);
+                if (status)
+                        dev_err(&ts->spi->dev, "spi_async --> %d\n",
+                                        status);
+        }
+        spin_unlock_irqrestore(&ts->lock, flags);
+}
+
+static irqreturn_t ads7846_irq(int irq, void *handle, struct pt_regs *regs)
+{
+        ads7846_timer((unsigned long) handle);
+        return IRQ_HANDLED;
+}
+
+/*--------------------------------------------------------------------------*/
+
+/* non-empty "extra" is needed before 2.6.14-git5 or so */
+#define EXTRA   //      , u32 level
+#define EXTRA2  //      , 0
+
+static int
+ads7846_suspend(struct device *dev, pm_message_t message EXTRA)
+{
+        struct ads7846 *ts = dev_get_drvdata(dev);
+        unsigned long   flags;
+
+        spin_lock_irqsave(&ts->lock, flags);
+
+        ts->spi->dev.power.power_state = message;
+
+        /* are we waiting for IRQ, or polling? */
+        if (!ts->pendown) {
+                if (!ts->irq_disabled) {
+                        ts->irq_disabled = 1;
+                        disable_irq(ts->spi->irq);
+                }
+        } else {
+                /* polling; force a final SPI completion;
+                 * that will clean things up neatly
+                 */
+                if (!ts->pending)
+                        mod_timer(&ts->timer, jiffies);
+
+                while (ts->pendown || ts->pending) {
+                        spin_unlock_irqrestore(&ts->lock, flags);
+                        udelay(10);
+                        spin_lock_irqsave(&ts->lock, flags);
+                }
+        }
+
+        /* we know the chip's in lowpower mode since we always
+         * leave it that way after every request
+         */
+
+        spin_unlock_irqrestore(&ts->lock, flags);
+        return 0;
+}
+
+static int ads7846_resume(struct device *dev EXTRA)
+{
+        struct ads7846 *ts = dev_get_drvdata(dev);
+
+        ts->irq_disabled = 0;
+        enable_irq(ts->spi->irq);
+        dev->power.power_state = PMSG_ON;
+        return 0;
+}
+
+static int __init ads7846_probe(struct device *dev)
+{
+        struct spi_device               *spi = to_spi_device(dev);
+        struct ads7846                  *ts;
+        struct ads7846_platform_data    *pdata = dev->platform_data;
+        struct spi_transfer             *x;
+
+        if (!spi->irq) {
+                dev_dbg(dev, "no IRQ?\n");
+                return -ENODEV;
+        }
+
+        if (!pdata) {
+                dev_dbg(dev, "no platform data?\n");
+                return -ENODEV;
+        }
+
+        /* don't exceed max specified sample rate */
+        if (spi->max_speed_hz > (125000 * 16)) {
+                dev_dbg(dev, "f(sample) %d KHz?\n",
+                                (spi->max_speed_hz/16)/1000);
+                return -EINVAL;
+        }
+
+        /* We'd set the wordsize to 12 bits ... except that some controllers
+         * will then treat the 8 bit command words as 12 bits (and drop the
+         * four MSBs of the 12 bit result).  Result: inputs must be shifted
+         * to discard the four garbage LSBs.
+         */
+
+        if (!(ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL)))
+                return -ENOMEM;
+
+        dev_set_drvdata(dev, ts);
+
+        ts->spi = spi;
+        spi->dev.power.power_state = PMSG_ON;
+
+        init_timer(&ts->timer);
+        ts->timer.data = (unsigned long) ts;
+        ts->timer.function = ads7846_timer;
+
+        ts->model = pdata->model ? : 7846;
+        ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
+        ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
+
+        init_input_dev(&ts->input);
+
+        ts->input.dev = dev;
+        ts->input.name = "ADS784x Touchscreen";
+        snprintf(ts->phys, sizeof ts->phys, "%s/input0", dev->bus_id);
+        ts->input.phys = ts->phys;
+
+        ts->input.evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
+        ts->input.keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
+        input_set_abs_params(&ts->input, ABS_X,
+                        pdata->x_min ? : 0,
+                        pdata->x_max ? : MAX_12BIT,
+                        0, 0);
+        input_set_abs_params(&ts->input, ABS_Y,
+                        pdata->y_min ? : 0,
+                        pdata->y_max ? : MAX_12BIT,
+                        0, 0);
+        input_set_abs_params(&ts->input, ABS_PRESSURE,
+                        pdata->pressure_min, pdata->pressure_max, 0, 0);
+
+        input_register_device(&ts->input);
+
+        /* set up the transfers to read touchscreen state; this assumes we
+         * use formula #2 for pressure, not #3.
+         */
+        x = ts->xfer;
+
+        /* y- still on; turn on only y+ (and ADC) */
+        x->tx_buf = &read_y;
+        x->len = 1;
+        x++;
+        x->rx_buf = &ts->tc.y;
+        x->len = 2;
+        x++;
+
+        /* turn y+ off, x- on; we'll use formula #2 */
+        if (ts->model == 7846) {
+                x->tx_buf = &read_z1;
+                x->len = 1;
+                x++;
+                x->rx_buf = &ts->tc.z1;
+                x->len = 2;
+                x++;
+
+                x->tx_buf = &read_z2;
+                x->len = 1;
+                x++;
+                x->rx_buf = &ts->tc.z2;
+                x->len = 2;
+                x++;
+        }
+
+        /* turn y- off, x+ on, then leave in lowpower */
+        x->tx_buf = &read_x;
+        x->len = 1;
+        x++;
+        x->rx_buf = &ts->tc.x;
+        x->len = 2;
+        x++;
+
+        CS_CHANGE(x[-1]);
+
+        ts->msg.transfers = ts->xfer;
+        ts->msg.n_transfer = x - ts->xfer;
+        ts->msg.complete = ads7846_rx;
+        ts->msg.context = ts;
+
+        if (request_irq(spi->irq, ads7846_irq, SA_SAMPLE_RANDOM,
+                                dev->bus_id, ts)) {
+                dev_dbg(dev, "irq %d busy?\n", spi->irq);
+                input_unregister_device(&ts->input);
+                kfree(ts);
+                return -EBUSY;
+        }
+        set_irq_type(spi->irq, IRQT_FALLING);
+
+        dev_info(dev, "touchscreen, irq %d\n", spi->irq);
+
+        /* take a first sample, leaving nPENIRQ active; avoid
+         * the touchscreen, in case it's not connected.
+         */
+        (void) ads7846_read12_ser(dev,
+                          READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
+
+        /* ads7843/7845 don't have temperature sensors, and
+         * use the other sensors a bit differently too
+         */
+        if (ts->model == 7846) {
+                device_create_file(dev, &dev_attr_temp0);
+                device_create_file(dev, &dev_attr_temp1);
+        }
+        if (ts->model != 7845)
+                device_create_file(dev, &dev_attr_vbatt);
+        device_create_file(dev, &dev_attr_vaux);
+
+        return 0;
+}
+
+static int __exit ads7846_remove(struct device *dev)
+{
+        struct ads7846          *ts = dev_get_drvdata(dev);
+
+        ads7846_suspend(dev, PMSG_SUSPEND EXTRA2);
+        free_irq(ts->spi->irq, ts);
+        if (ts->irq_disabled)
+                enable_irq(ts->spi->irq);
+
+        if (ts->model == 7846) {
+                device_remove_file(dev, &dev_attr_temp0);
+                device_remove_file(dev, &dev_attr_temp1);
+        }
+        if (ts->model != 7845)
+                device_remove_file(dev, &dev_attr_vbatt);
+        device_remove_file(dev, &dev_attr_vaux);
+
+        input_unregister_device(&ts->input);
+        kfree(ts);
+
+        dev_dbg(dev, "unregistered touchscreen\n");
+        return 0;
+}
+
+static struct device_driver ads7846_driver = {
+        .name           = "ads7846",
+        .bus            = &spi_bus_type,
+        .probe          = ads7846_probe,
+        .remove         = __exit_p(ads7846_remove),
+        .suspend        = ads7846_suspend,
+        .resume         = ads7846_resume,
+};
+
+static int __init ads7846_init(void)
+{
+        /* grr, board-specific init should stay out of drivers!! */
+
+#ifdef  CONFIG_ARCH_OMAP
+        if (machine_is_omap_osk()) {
+                /* GPIO4 = PENIRQ; GPIO6 = BUSY */
+                omap_request_gpio(4);
+                omap_set_gpio_direction(4, 1);
+                omap_request_gpio(6);
+                omap_set_gpio_direction(6, 1);
+        }
+        // also TI 1510 Innovator, bitbanging through FPGA
+        // also Nokia 770
+        // also Palm Tungsten T2
+#endif
+
+        // PXA:
+        // also Dell Axim X50
+        // also HP iPaq H191x/H192x/H415x/H435x
+        // also Intel Lubbock (alternate to UCB1400)
+        // also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)
+
+        // also various AMD Au1x00 devel boards
+
+        return driver_register(&ads7846_driver);
+}
+module_init(ads7846_init);
+
+static void __exit ads7846_exit(void)
+{
+        driver_unregister(&ads7846_driver);
+
+#ifdef  CONFIG_ARCH_OMAP
+        if (machine_is_omap_osk()) {
+                omap_free_gpio(4);
+                omap_free_gpio(6);
+        }
+#endif
+
+}
+module_exit(ads7846_exit);
+
+MODULE_DESCRIPTION("ADS7846 TouchScreen Driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h
new file mode 100644
index 000000000000..84a27013d399
--- /dev/null
+++ b/include/linux/spi/ads7846.h
@@ -0,0 +1,18 @@
+/* linux/spi/ads7846.h */
+
+/* Touchscreen characteristics vary between boards and models.  The
+ * platform_data for the device's "struct device" holts this information.
+ *
+ * It's OK if the min/max values are zero.
+ */
+struct ads7846_platform_data {
+        u16     model;                  /* 7843, 7845, 7846. */
+        u16     vref_delay_usecs;       /* 0 for external vref; etc */
+        u16     x_plate_ohms;
+        u16     y_plate_ohms;
+
+        u16     x_min, x_max;
+        u16     y_min, y_max;
+        u16     pressure_min, pressure_max;
+};
+