--- /dev/null
+/*
+ * 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");
projects / linux-2.6 / commitdiff