From da970e69efb9fd0be0c23ace5bde42d4caf17b40 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Thu, 18 Jan 2007 00:44:41 -0500 Subject: Input: ads7846 - pluggable filtering logic Some LCDs like the LS041Y3 require a customized filtering logic for reliable readings, so make the filtering function replacable through platform specific hooks. Signed-off-by: Imre Deak Signed-off-by: Juha Yrjola Signed-off-by: David Brownell Signed-off-by: Dmitry Torokhov --- drivers/input/touchscreen/ads7846.c | 135 +++++++++++++++++++++++++----------- 1 file changed, 95 insertions(+), 40 deletions(-) (limited to 'drivers/input/touchscreen') diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index c6164b6f476..03e527c16c2 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -63,11 +63,11 @@ 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-bit values, - * which need byteswapping then range adjustment. + * *** WHICH NEED BYTESWAPPING *** and range adjustment. */ - __be16 x; - __be16 y; - __be16 z1, z2; + u16 x; + u16 y; + u16 z1, z2; int ignore; }; @@ -106,6 +106,9 @@ struct ads7846 { unsigned irq_disabled:1; /* P: lock */ unsigned disabled:1; + int (*filter)(void *data, int data_idx, int *val); + void *filter_data; + void (*filter_cleanup)(void *data); int (*get_pendown_state)(void); }; @@ -379,13 +382,13 @@ static void ads7846_rx(void *ads) u16 x, y, z1, z2; unsigned long flags; - /* adjust: on-wire is a must-ignore bit, a BE12 value, then padding; - * built from two 8 bit values written msb-first. + /* ads7846_rx_val() did in-place conversion (including byteswap) from + * on-the-wire format as part of debouncing to get stable readings. */ - x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff; - y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff; - z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff; - z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff; + x = ts->tc.x; + y = ts->tc.y; + z1 = ts->tc.z1; + z2 = ts->tc.z2; /* range filtering */ if (x == MAX_12BIT) @@ -453,50 +456,85 @@ static void ads7846_rx(void *ads) spin_unlock_irqrestore(&ts->lock, flags); } -static void ads7846_debounce(void *ads) +static int ads7846_debounce(void *ads, int data_idx, int *val) { struct ads7846 *ts = ads; - struct spi_message *m; - struct spi_transfer *t; - int val; - int status; - m = &ts->msg[ts->msg_idx]; - t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list); - val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff; - if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) { + if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) { + /* Start over collecting consistent readings. */ + ts->read_rep = 0; /* Repeat it, if this was the first read or the read * wasn't consistent enough. */ if (ts->read_cnt < ts->debounce_max) { - ts->last_read = val; + ts->last_read = *val; ts->read_cnt++; + return ADS7846_FILTER_REPEAT; } else { /* 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->tc.ignore = 1; ts->read_cnt = 0; - /* Last message will contain ads7846_rx() as the - * completion function. - */ - m = ts->last_msg; + return ADS7846_FILTER_IGNORE; } - /* Start over collecting consistent readings. */ - ts->read_rep = 0; } else { if (++ts->read_rep > ts->debounce_rep) { /* Got a good reading for this coordinate, * go for the next one. */ - ts->tc.ignore = 0; - ts->msg_idx++; ts->read_cnt = 0; ts->read_rep = 0; - m++; - } else + 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) @@ -689,14 +727,25 @@ static int __devinit ads7846_probe(struct spi_device *spi) 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) { + + 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; - if (ts->debounce_rep > ts->debounce_max + 1) - ts->debounce_rep = ts->debounce_max - 1; + ts->filter = ads7846_debounce; + ts->filter_data = ts; } else - ts->debounce_tol = ~0; + ts->filter = ads7846_no_filter; ts->get_pendown_state = pdata->get_pendown_state; snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id); @@ -737,7 +786,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) x->len = 2; spi_message_add_tail(x, m); - m->complete = ads7846_debounce; + m->complete = ads7846_rx_val; m->context = ts; m++; @@ -755,7 +804,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) x->len = 2; spi_message_add_tail(x, m); - m->complete = ads7846_debounce; + m->complete = ads7846_rx_val; m->context = ts; /* turn y+ off, x- on; we'll use formula #2 */ @@ -774,7 +823,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) x->len = 2; spi_message_add_tail(x, m); - m->complete = ads7846_debounce; + m->complete = ads7846_rx_val; m->context = ts; m++; @@ -791,7 +840,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) x->len = 2; spi_message_add_tail(x, m); - m->complete = ads7846_debounce; + m->complete = ads7846_rx_val; m->context = ts; } @@ -820,7 +869,7 @@ static int __devinit ads7846_probe(struct spi_device *spi) spi->dev.driver->name, ts)) { dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq); err = -EBUSY; - goto err_free_mem; + goto err_cleanup_filter; } dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq); @@ -856,6 +905,9 @@ static int __devinit ads7846_probe(struct spi_device *spi) sysfs_remove_group(&spi->dev.kobj, ts->attr_group); 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); @@ -876,6 +928,9 @@ static int __devexit ads7846_remove(struct spi_device *spi) /* 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"); -- cgit v1.2.3