Input: ads7846 - introduce platform specific way to synchronize sampling
Noises can be introduced when LCD signals are being driven, some platforms provide a signal to assist the synchronization of this sampling procedure. Signed-off-by: Eric Miao <eric.miao@marvell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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@ -127,6 +127,8 @@ struct ads7846 {
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void (*filter_cleanup)(void *data);
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int (*get_pendown_state)(void);
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int gpio_pendown;
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void (*wait_for_sync)(void);
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};
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/* leave chip selected when we're done, for quicker re-select? */
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@ -511,6 +513,10 @@ static int get_pendown_state(struct ads7846 *ts)
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return !gpio_get_value(ts->gpio_pendown);
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}
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static void null_wait_for_sync(void)
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{
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}
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/*
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* PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
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* to retrieve touchscreen status.
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@ -686,6 +692,7 @@ static void ads7846_rx_val(void *ads)
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default:
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BUG();
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}
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ts->wait_for_sync();
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status = spi_async(ts->spi, m);
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if (status)
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dev_err(&ts->spi->dev, "spi_async --> %d\n",
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@ -723,6 +730,7 @@ static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
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} else {
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/* pen is still down, continue with the measurement */
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ts->msg_idx = 0;
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ts->wait_for_sync();
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status = spi_async(ts->spi, &ts->msg[0]);
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if (status)
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dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
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@ -947,6 +955,8 @@ static int __devinit ads7846_probe(struct spi_device *spi)
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ts->penirq_recheck_delay_usecs =
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pdata->penirq_recheck_delay_usecs;
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ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
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snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
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input_dev->name = "ADS784x Touchscreen";
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@ -51,5 +51,6 @@ struct ads7846_platform_data {
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void **filter_data);
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int (*filter) (void *filter_data, int data_idx, int *val);
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void (*filter_cleanup)(void *filter_data);
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void (*wait_for_sync)(void);
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};
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