ads7846.c

linux 内核源代码

			/* Maximum number of debouncing reached and still
			 * not enough number of consistent readings. Abort
			 * the whole sample, repeat it in the next sampling
			 * period.
			 */
			ts->read_cnt = 0;
			return ADS7846_FILTER_IGNORE;
		}
	} else {
		if (++ts->read_rep > ts->debounce_rep) {
			/* Got a good reading for this coordinate,
			 * go for the next one. */
			ts->read_cnt = 0;
			ts->read_rep = 0;
			return ADS7846_FILTER_OK;
		} else {
			/* Read more values that are consistent. */
			ts->read_cnt++;
			return ADS7846_FILTER_REPEAT;
		}
	}
}

static int ads7846_no_filter(void *ads, int data_idx, int *val)
{
	return ADS7846_FILTER_OK;
}

static void ads7846_rx_val(void *ads)
{
	struct ads7846 *ts = ads;
	struct spi_message *m;
	struct spi_transfer *t;
	u16 *rx_val;
	int val;
	int action;
	int status;

	m = &ts->msg[ts->msg_idx];
	t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
	rx_val = t->rx_buf;

	/* 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_cpu(*rx_val) >> 3;

	action = ts->filter(ts->filter_data, ts->msg_idx, &val);
	switch (action) {
	case ADS7846_FILTER_REPEAT:
		break;
	case ADS7846_FILTER_IGNORE:
		ts->tc.ignore = 1;
		/* Last message will contain ads7846_rx() as the
		 * completion function.
		 */
		m = ts->last_msg;
		break;
	case ADS7846_FILTER_OK:
		*rx_val = val;
		ts->tc.ignore = 0;
		m = &ts->msg[++ts->msg_idx];
		break;
	default:
		BUG();
	}
	status = spi_async(ts->spi, m);
	if (status)
		dev_err(&ts->spi->dev, "spi_async --> %d\n",
				status);
}

static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
{
	struct ads7846	*ts = container_of(handle, struct ads7846, timer);
	int		status = 0;

	spin_lock_irq(&ts->lock);

	if (unlikely(!ts->get_pendown_state() ||
		     device_suspended(&ts->spi->dev))) {
		if (ts->pendown) {
			struct input_dev *input = ts->input;

			input_report_key(input, BTN_TOUCH, 0);
			input_report_abs(input, ABS_PRESSURE, 0);
			input_sync(input);

			ts->pendown = 0;
#ifdef VERBOSE
			dev_dbg(&ts->spi->dev, "UP\n");
#endif
		}

		/* measurement cycle ended */
		if (!device_suspended(&ts->spi->dev)) {
			ts->irq_disabled = 0;
			enable_irq(ts->spi->irq);
		}
		ts->pending = 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);
	return HRTIMER_NORESTART;
}

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;
			hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
					HRTIMER_MODE_REL);
		}
	}
	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				vref;
	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;
	spi->mode = SPI_MODE_0;
	err = spi_setup(spi);
	if (err < 0)
		return err;

	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;

	hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	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->filter != NULL) {
		if (pdata->filter_init != NULL) {
			err = pdata->filter_init(pdata, &ts->filter_data);
			if (err < 0)
				goto err_free_mem;
		}
		ts->filter = pdata->filter;
		ts->filter_cleanup = pdata->filter_cleanup;
	} else if (pdata->debounce_max) {
		ts->debounce_max = pdata->debounce_max;
		if (ts->debounce_max < 2)
			ts->debounce_max = 2;
		ts->debounce_tol = pdata->debounce_tol;
		ts->debounce_rep = pdata->debounce_rep;
		ts->filter = ads7846_debounce;
		ts->filter_data = ts;
	} else
		ts->filter = ads7846_no_filter;
	ts->get_pendown_state = pdata->get_pendown_state;

	if (pdata->penirq_recheck_delay_usecs)
		ts->penirq_recheck_delay_usecs =
				pdata->penirq_recheck_delay_usecs;

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

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

	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(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);

	vref = pdata->keep_vref_on;

	/* 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) */
	ts->read_y = READ_Y(vref);
	x->tx_buf = &ts->read_y;
	x->len = 1;
	spi_message_add_tail(x, m);

	x++;
	x->rx_buf = &ts->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
	 * have had enough time to stabilize.
	 */
	if (pdata->settle_delay_usecs) {
		x->delay_usecs = pdata->settle_delay_usecs;

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

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

	m->complete = ads7846_rx_val;
	m->context = ts;

	m++;
	spi_message_init(m);

	/* turn y- off, x+ on, then leave in lowpower */
	x++;
	ts->read_x = READ_X(vref);
	x->tx_buf = &ts->read_x;
	x->len = 1;
	spi_message_add_tail(x, m);

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

	/* ... maybe discard first sample ... */
	if (pdata->settle_delay_usecs) {
		x->delay_usecs = pdata->settle_delay_usecs;

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

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

	m->complete = ads7846_rx_val;
	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(vref);
		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);

		/* ... maybe discard first sample ... */
		if (pdata->settle_delay_usecs) {
			x->delay_usecs = pdata->settle_delay_usecs;

			x++;
			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_rx_val;
		m->context = ts;

		m++;
		spi_message_init(m);

		x++;
		ts->read_z2 = READ_Z2(vref);
		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);

		/* ... maybe discard first sample ... */
		if (pdata->settle_delay_usecs) {
			x->delay_usecs = pdata->settle_delay_usecs;

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

	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_cleanup_filter;
	}

	err = ads784x_hwmon_register(spi, ts);
	if (err)
		goto err_free_irq;

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

	/* 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);

	err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
	if (err)
		goto err_remove_hwmon;

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

	return 0;

 err_remove_attr_group:
	sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
 err_remove_hwmon:
	ads784x_hwmon_unregister(spi, ts);
 err_free_irq:
	free_irq(spi->irq, ts);
 err_cleanup_filter:
	if (ts->filter_cleanup)
		ts->filter_cleanup(ts->filter_data);
 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);

	ads784x_hwmon_unregister(spi, ts);
	input_unregister_device(ts->input);

	ads7846_suspend(spi, PMSG_SUSPEND);

	sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);

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

	if (ts->filter_cleanup)
		ts->filter_cleanup(ts->filter_data);

	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");