ads7846.c

Touchright serial touchscreen driver

			ts->read_rep = 0;
			m++;
		} else
			/* Read more values that are consistent. */
			ts->read_cnt++;
	}
	status = spi_async(ts->spi, m);
	if (status)
		dev_err(&ts->spi->dev, "spi_async --> %d\n",
				status);
}

static void ads7846_timer(unsigned long handle)
{
	struct ads7846	*ts = (void *)handle;
	int		status = 0;
	int		alt_end_cycle = 0; /* ads7843 alternative cycle end */

	if (ts->model == 7843) {
		/* get sample */
		ts->pendown = ts->get_pendown_state();
		alt_end_cycle = ts->pending;
	}

	spin_lock_irq(&ts->lock);

	if (unlikely(!ts->pendown && (ts->msg_idx || alt_end_cycle))) {
		/* measurement cycle ended */
		if (ts->model == 7843) {
			status = spi_async(ts->spi, ts->last_msg);
			if (status)
				dev_err(&ts->spi->dev,
					"spi_async --> %d\n", status);
		}

		if (!device_suspended(&ts->spi->dev)) {
			ts->irq_disabled = 0;
			enable_irq(ts->spi->irq);
		}
		ts->pending = 0;
		ts->msg_idx = 0;
	} else {
		/* pen is still down, continue with the measurement */
		ts->msg_idx = 0;
		status = spi_async(ts->spi, &ts->msg[0]);
		if (status)
			dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
	}

	spin_unlock_irq(&ts->lock);
}

static irqreturn_t ads7846_irq(int irq, void *handle)
{
	struct ads7846 *ts = handle;
	unsigned long flags;

	spin_lock_irqsave(&ts->lock, flags);
	if (likely(ts->get_pendown_state())) {
		if (!ts->irq_disabled) {
			/* The ARM do_simple_IRQ() dispatcher doesn't act
			 * like the other dispatchers:  it will report IRQs
			 * even after they've been disabled.  We work around
			 * that here.  (The "generic irq" framework may help...)
			 */
			ts->irq_disabled = 1;
			disable_irq(ts->spi->irq);
			ts->pending = 1;
			mod_timer(&ts->timer, jiffies);
		}
	}
	spin_unlock_irqrestore(&ts->lock, flags);

	return IRQ_HANDLED;
}

/*--------------------------------------------------------------------------*/

/* Must be called with ts->lock held */
static void ads7846_disable(struct ads7846 *ts)
{
	if (ts->disabled)
		return;

	ts->disabled = 1;

	/* are we waiting for IRQ, or polling? */
	if (!ts->pending) {
		ts->irq_disabled = 1;
		disable_irq(ts->spi->irq);
	} else {
		/* the timer will run at least once more, and
		 * leave everything in a clean state, IRQ disabled
		 */
		while (ts->pending) {
			spin_unlock_irq(&ts->lock);
			msleep(1);
			spin_lock_irq(&ts->lock);
		}
	}

	/* we know the chip's in lowpower mode since we always
	 * leave it that way after every request
	 */

}

/* Must be called with ts->lock held */
static void ads7846_enable(struct ads7846 *ts)
{
	if (!ts->disabled)
		return;

	ts->disabled = 0;
	ts->irq_disabled = 0;
	enable_irq(ts->spi->irq);
}

static int ads7846_suspend(struct spi_device *spi, pm_message_t message)
{
	struct ads7846 *ts = dev_get_drvdata(&spi->dev);

	spin_lock_irq(&ts->lock);

	spi->dev.power.power_state = message;
	ads7846_disable(ts);

	spin_unlock_irq(&ts->lock);

	return 0;

}

static int ads7846_resume(struct spi_device *spi)
{
	struct ads7846 *ts = dev_get_drvdata(&spi->dev);

	spin_lock_irq(&ts->lock);

	spi->dev.power.power_state = PMSG_ON;
	ads7846_enable(ts);

	spin_unlock_irq(&ts->lock);

	return 0;
}

static int __devinit ads7846_probe(struct spi_device *spi)
{
	struct ads7846			*ts;
	struct input_dev		*input_dev;
	struct ads7846_platform_data	*pdata = spi->dev.platform_data;
	struct spi_message		*m;
	struct spi_transfer		*x;
	int				err;

	if (!spi->irq) {
		dev_dbg(&spi->dev, "no IRQ?\n");
		return -ENODEV;
	}

	if (!pdata) {
		dev_dbg(&spi->dev, "no platform data?\n");
		return -ENODEV;
	}

	/* don't exceed max specified sample rate */
	if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) {
		dev_dbg(&spi->dev, "f(sample) %d KHz?\n",
				(spi->max_speed_hz/SAMPLE_BITS)/1000);
		return -EINVAL;
	}

	/* REVISIT when the irq can be triggered active-low, or if for some
	 * reason the touchscreen isn't hooked up, we don't need to access
	 * the pendown state.
	 */
	if (pdata->get_pendown_state == NULL) {
		dev_dbg(&spi->dev, "no get_pendown_state function?\n");
		return -EINVAL;
	}

	/* We'd set TX wordsize 8 bits and RX wordsize to 13 bits ... except
	 * that even if the hardware can do that, the SPI controller driver
	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
	 */
	spi->bits_per_word = 8;

	ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
	input_dev = input_allocate_device();
	if (!ts || !input_dev) {
		err = -ENOMEM;
		goto err_free_mem;
	}

	dev_set_drvdata(&spi->dev, ts);
	spi->dev.power.power_state = PMSG_ON;

	ts->spi = spi;
	ts->input = input_dev;

	init_timer(&ts->timer);
	ts->timer.data = (unsigned long) ts;
	ts->timer.function = ads7846_timer;

	spin_lock_init(&ts->lock);

	ts->model = pdata->model ? : 7846;
	ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
	ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
	ts->pressure_max = pdata->pressure_max ? : ~0;
	if (pdata->debounce_max) {
		ts->debounce_max = pdata->debounce_max;
		ts->debounce_tol = pdata->debounce_tol;
		ts->debounce_rep = pdata->debounce_rep;
		if (ts->debounce_rep > ts->debounce_max + 1)
			ts->debounce_rep = ts->debounce_max - 1;
	} else
		ts->debounce_tol = ~0;
	ts->get_pendown_state = pdata->get_pendown_state;

	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);

	input_dev->name = "ADS784x Touchscreen";
	input_dev->phys = ts->phys;
	input_dev->cdev.dev = &spi->dev;

	input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
	input_dev->keybit[LONG(BTN_TOUCH)] = BIT(BTN_TOUCH);
	input_set_abs_params(input_dev, ABS_X,
			pdata->x_min ? : 0,
			pdata->x_max ? : MAX_12BIT,
			0, 0);
	input_set_abs_params(input_dev, ABS_Y,
			pdata->y_min ? : 0,
			pdata->y_max ? : MAX_12BIT,
			0, 0);
	input_set_abs_params(input_dev, ABS_PRESSURE,
			pdata->pressure_min, pdata->pressure_max, 0, 0);

	/* set up the transfers to read touchscreen state; this assumes we
	 * use formula #2 for pressure, not #3.
	 */
	m = &ts->msg[0];
	x = ts->xfer;

	spi_message_init(m);

	/* y- still on; turn on only y+ (and ADC) */
	if (ts->model == 7843) {
		ts->read_y = ALT_READ_Y;
	} else {
		ts->read_y = READ_Y;
	}
	x->tx_buf = &ts->read_y;
	x->len = 1;
	spi_message_add_tail(x, m);

	x++;
	x->tx_buf = &ts->zerro;
	x->rx_buf = &ts->tc.y;
	x->len = 2;
	spi_message_add_tail(x, m);

	m->complete = ads7846_debounce;
	m->context = ts;

	m++;
	spi_message_init(m);

	/* turn y- off, x+ on, then leave in lowpower */
	x++;
	if (ts->model == 7843) {
		ts->read_x = ALT_READ_X;
	} else {
		ts->read_x = READ_X;
	}
	x->tx_buf = &ts->read_x;
	x->len = 1;
	spi_message_add_tail(x, m);

	x++;
	x->tx_buf = &ts->zerro;
	x->rx_buf = &ts->tc.x;
	x->len = 2;
	spi_message_add_tail(x, m);

	m->complete = ads7846_debounce;
	m->context = ts;

	/* turn y+ off, x- on; we'll use formula #2 */
	if (ts->model == 7846) {
		m++;
		spi_message_init(m);

		x++;
		ts->read_z1 = READ_Z1;
		x->tx_buf = &ts->read_z1;
		x->len = 1;
		spi_message_add_tail(x, m);

		x++;
		x->rx_buf = &ts->tc.z1;
		x->len = 2;
		spi_message_add_tail(x, m);

		m->complete = ads7846_debounce;
		m->context = ts;

		m++;
		spi_message_init(m);

		x++;
		ts->read_z2 = READ_Z2;
		x->tx_buf = &ts->read_z2;
		x->len = 1;
		spi_message_add_tail(x, m);

		x++;
		x->rx_buf = &ts->tc.z2;
		x->len = 2;
		spi_message_add_tail(x, m);

		m->complete = ads7846_debounce;
		m->context = ts;
	}

	/* power down */
	m++;
	spi_message_init(m);

	x++;
	ts->pwrdown = PWRDOWN;
	x->tx_buf = &ts->pwrdown;
	x->len = 1;
	spi_message_add_tail(x, m);

	x++;
	x->tx_buf = &ts->zerro;
	x->rx_buf = &ts->dummy;
	x->len = 2;
	CS_CHANGE(*x);
	spi_message_add_tail(x, m);

	if (ts->model == 7843) {
		m->complete = ads7843_rx;
	} else {
		m->complete = ads7846_rx;
	}
	m->context = ts;

	ts->last_msg = m;

	if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
			spi->dev.driver->name, ts)) {
		dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
		err = -EBUSY;
		goto err_free_mem;
	}

	dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);

	if (ts->model != 7843) {
		/* take a first sample, leaving nPENIRQ active; avoid
		 * the touchscreen, in case it's not connected.
		 */
		(void) ads7846_read12_ser(&spi->dev,
				  READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
	} else {
		(void) ads7846_read12_ser(&spi->dev,
				  READ_12BIT_DFR(y) | 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(&spi->dev, &dev_attr_temp0);
		device_create_file(&spi->dev, &dev_attr_temp1);
	}
	if (ts->model != 7845 && ts->model != 7843)
		device_create_file(&spi->dev, &dev_attr_vbatt);

	if (ts->model != 7843) {
		device_create_file(&spi->dev, &dev_attr_vaux);
	}

	device_create_file(&spi->dev, &dev_attr_pen_down);
	device_create_file(&spi->dev, &dev_attr_disable);

	err = input_register_device(input_dev);
	if (err)
		goto err_remove_attr;

	return 0;

 err_remove_attr:
	device_remove_file(&spi->dev, &dev_attr_disable);
	device_remove_file(&spi->dev, &dev_attr_pen_down);
	if (ts->model == 7846) {
		device_remove_file(&spi->dev, &dev_attr_temp1);
		device_remove_file(&spi->dev, &dev_attr_temp0);
	}
	if (ts->model != 7845 && ts->model != 7843)
		device_remove_file(&spi->dev, &dev_attr_vbatt);

	if (ts->model != 7843) {
		device_remove_file(&spi->dev, &dev_attr_vaux);
	}

	free_irq(spi->irq, ts);
 err_free_mem:
	input_free_device(input_dev);
	kfree(ts);
	return err;
}

static int __devexit ads7846_remove(struct spi_device *spi)
{
	struct ads7846		*ts = dev_get_drvdata(&spi->dev);

	input_unregister_device(ts->input);

	ads7846_suspend(spi, PMSG_SUSPEND);

	device_remove_file(&spi->dev, &dev_attr_disable);
	device_remove_file(&spi->dev, &dev_attr_pen_down);
	if (ts->model == 7846) {
		device_remove_file(&spi->dev, &dev_attr_temp1);
		device_remove_file(&spi->dev, &dev_attr_temp0);
	}
	if (ts->model != 7845 && ts->model != 7843)
		device_remove_file(&spi->dev, &dev_attr_vbatt);

	if (ts->model != 7843) {
		device_remove_file(&spi->dev, &dev_attr_vaux);
	}

	free_irq(ts->spi->irq, ts);
	/* suspend left the IRQ disabled */
	enable_irq(ts->spi->irq);

	kfree(ts);

	dev_dbg(&spi->dev, "unregistered touchscreen\n");
	return 0;
}

static struct spi_driver ads7846_driver = {
	.driver = {
		.name	= "ads7846",
		.bus	= &spi_bus_type,
		.owner	= THIS_MODULE,
	},
	.probe		= ads7846_probe,
	.remove		= __devexit_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 (additional to UCB1400; as temperature sensor)
	// also Sharp Zaurus C7xx, C8xx (corgi/sheperd/husky)

	// Atmel at91sam9261-EK uses ads7843

	// also various AMD Au1x00 devel boards

	return spi_register_driver(&ads7846_driver);
}
module_init(ads7846_init);

static void __exit ads7846_exit(void)
{
	spi_unregister_driver(&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");